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Title:
METHOD FOR CONSTRUCTING CONTINUOUS UNDERGROUND WALL AND STEEL PIPE PILE
Document Type and Number:
WIPO Patent Application WO/2019/017498
Kind Code:
A1
Abstract:
A method for constructing a continuous underground wall includes: a steel pipe installation step of continuously alternately installing first steel pipes and second steel pipes in a construction direction; an excavation step of excavating a content in each of the first steel pipes and the second steel pipes; a first solidification material-filling step of pulling out the first steel pipe while the first steel pipe is being filled with concrete and after the first steel pipe has been filled with concrete; and a second solidification material-filling step of pulling out the second steel pipe while first piles are being disturbed using claws protruding to the outside of the second steel pipe while the second steel pipe is being filled with concrete or after the second steel pipe has been filled with concrete. Both sides of a second pile are joined to the first piles using replenishing concrete while the first pile is being disturbed using the claws.

Inventors:
KITAMURA AKIO (JP)
Application Number:
PCT/JP2018/027786
Publication Date:
January 24, 2019
Filing Date:
July 18, 2018
Export Citation:
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Assignee:
GIKEN LTD (JP)
International Classes:
E02D5/28; E02D5/68; E02D19/18
Domestic Patent References:
WO2011132894A22011-10-27
Foreign References:
JPH09119131A1997-05-06
NL1021310C22004-02-24
JP2012237138A2012-12-06
JPH05339936A1993-12-21
DE3428297A11986-02-27
US5758993A1998-06-02
JP2001090060A2001-04-03
JP2012237138A2012-12-06
Attorney, Agent or Firm:
TANAI, Sumio et al. (Marunouchi Chiyoda-k, Tokyo 20, JP)
Download PDF:
Claims:
[CLAIMS]

[Claim 1]

A method for constructing a continuous underground wall, comprising:

a steel pipe installation step of continuously alternately installing first steel pipes and second steel pipes in a construction direction;

an excavation step of excavating a content in each of the first steel pipes and the second steel pipes while the first steel pipe and the second steel pipe are being installed or after the first steel pipe and the second steel pipe have been installed;

a first solidification material-filling step of pulling out the first steel pipes when the first steel pipes arranged as every other steel pipe are being filled with a solidifying material or after the first steel pipes have been filled with a solidifying material; and a second solidification material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material-filling step is being disturbed using claws protruding outside of the second steel pipe while the second steel pipe arranged between the first steel pipes is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

[Claim 2]

A method for constructing a continuous underground wall, comprising:

a first steel pipe installation step of installing first steel pipes at intervals in a construction direction;

a first excavation step of excavating the content in each of the first steel pipes while the first steel pipe is being installed or after the first steel pipe has been installed; a first solidification material-filling step of pulling out the first steel pipe while the first steel pipe is being filled with a solidifying material or after the first steel pipe has been filled with a solidifying material; a second steel pipe installation step of installing the second steel pipe between the first steel pipes;

a second excavation step of excavating the content in each of the second steel pipe while the second steel pipe is being installed or after the second steel pipe has been installed; and

a second solidification material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material-filling step is being disturbed using claws protruding to the outside of the second steel pipe while the second steel pipe is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

[Claim 3]

A method for constructing a continuous underground wall, comprising:

a second steel pipe installation step of installing second steel pipes at intervals in a construction direction;

a second excavation step of excavating a content in each of the second steel pipe while the second steel pipe is being installed or after the second steel pipe has been installed;

a first steel pipe installation step of installing a first steel pipe between the second steel pipes;

a first excavation step of excavating the content of the first steel pipe while the first steel pipe is being installed or after the first steel pipe has been installed;

a first solidification material-filling step of pulling out the first steel pipe while the first steel pipe is being filled with a solidifying material or after the first steel pipe has been filled with a solidifying material; and

a second solidification material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material-filling step is being disturbed using claws protruding to the outside of the second steel pipe while the second steel pipe is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

[Claim 4]

The method for constructing a continuous underground wall according to Claim 1 or 2, wherein the claws are provided in positions in which the claws do not interfere with the first steel pipe when the second steel pipe is installed.

[Claim 5]

The method for constructing a continuous underground wall according to any one of Claims 1 to 4, wherein the claws in the second steel pipe are provided in a gap between a circumscribing line of one of the first steel pipe and/or the second steel pipe or two opposite circumscribing lines of both of the first steel pipe and/or the second steel pipe and an adjacent first steel pipe.

[Claim 6]

The method for constructing a continuous underground wall according to any one of Claims 1 to 5, wherein the second steel pipe on which the claws are provided is installed through press-in, rotational press-in, or swingable press-in.

[Claim 7]

The method for constructing a continuous underground wall according to any one of Claims 1 to 6, wherein the solidifying material filled in the first solidification material-filling step is in a state of being between a solidification start time and a solidification termination time when the second steel pipe is pulled out.

[Claim 8]

The method for constructing a continuous underground wall according to any one of Claims 1 to 7, wherein the claws in the second steel pipe are expandable and contractible outward.

[Claim 9]

The method for constructing a continuous underground wall according to any one of Claims 1 to 8, wherein there is replenishment with new solidifying material while the solidifying material filled in the first solidification material-filling step is being disturbed using the claws when the second steel pipe is pulled out.

[Claim 10]

The method for constructing a continuous underground wall according to any one of Claims 1 to 9, wherein a press-in machine is installed in the first steel pipe and/or the second steel pipe so that the press-in machine installs and pulls out the first steel pipe and the second steel pipe.

[Claim 11]

The method for constructing a continuous underground wall according to any one of Claims 1 to 10, wherein prestressed concrete (PC) steel wires are installed in the excavated first steel pipe and/or second steel pipe, and

a first solidifying material corresponding to the first steel pipe and/or a second solidifying material corresponding to the second steel pipe are fixed and then the PC steel wires are tensioned and prestress is introduced into the first steel pipe and/or the second steel pipe.

[Claim 12]

The method for constructing a continuous underground wall according to any one of Claims 1 to 11, wherein the first steel pipe and the second steel pipe are pulled out and the first solidifying material and the second solidifying material are disturbed using the claws in a ground region, and the first steel pipe and the second steel pipe are held without being pulled out in water.

[Claim 13]

The method for constructing a continuous underground wall according to any one of Claims 1 to 11 , wherein the first steel pipe and the second steel pipe are pulled out in a ground region, the first solidifying material and the second solidifying material are disturbed using the claws, and the first steel pipe and the second steel pipe are held above the ground without being pulled out.

[Claim 14]

A steel pipe pile, comprising:

a steel pipe; and

claws protruding outward in a radial direction from a suitable position of the steel pipe in a longitudinal direction,

wherein adjacent solidifying material is disturbed using the claws when the steel pipe installed in the ground is pulled up.

Description:
[DESCRIPTION]

[TITLE OF INVENTION]

METHOD FOR CONSTRUCTING CONTINUOUS UNDERGROUND WALL AND STEEL PIPE PILE

[Technical Field]

[0001]

The present invention relates to a method for constructing a continuous underground wall formed by joining piles constituted of a solidifying material such as concrete to each other in the ground and a steel pipe pile used for constructing this continuous underground wall.

Priority is claimed on Japanese Patent Application No. 2017-141225, filed July 20, 2017, the content of which is incorporated herein by reference.

[Background Art]

[0002]

In the related art, it is known that continuous underground walls are constructed underground or in the ground as methods for constructing structures at construction sites. Furthermore, it is known that continuous underground walls are constructed as waterproofing walls.

In methods for constructing continuous underground walls in the related art, for example, when excavation holes are excavated at predetermined intervals in the ground, the excavation holes are filled with concrete, and when the concrete has semi-hardened and become self-standing, another excavation hole is excavated at that time and is filled with concrete, these pieces of concrete overlap, and continuous underground walls are constructed. In order to prevent collapse of the excavation holes, casings are installed in inlet portions, and the excavation holes are filled with bentonite solutions or the like. [0003]

In the method for constructing a waterproofing wall described in Patent

Literature 1 , a casing drills a hole and is inserted into the ground while earth and sand in the casing is being discharged and a steel pipe pile is placed in the casing. When the casing is pulled out while a solidifying material is being injected into the hole and a solidifying material ring is formed, piles with a double structure are installed as preceding piles at predetermined intervals. In addition, a continuous underground wall is formed by forming subsequent piles such that the solidifying material ring is wrapped between the preceding piles.

[0004]

In the method for constructing a continuous underground wall described in Patent Literature 2, a double-structure waterproofing pile body is formed by inserting a waterproofing bottomed tubular body on which a casing is attached into a vertical hole excavated in soft ground and filling the vertical hole with a hardening filling material through the bottomed tubular body. Moreover, an underground continuous water barrier is formed in which neighboring waterproofing pile bodies are mutually continuous such that pieces of the hardening filling material of the waterproofing pile bodies overlap. The pieces of hardening filling material provided on outer circumferential surfaces of the waterproofing bottomed tubular bodies are left and the casing is pulled up.

Moreover, the pieces of hardening filling material of the neighboring

waterproofing pile bodies are agitated using spiral agitating members provided on the outer circumferential surfaces of the waterproofing bottomed tubular bodies, the spiral agitating members are pulled up, and then the pieces of hardening filling material are hardened and a continuous underground wall is constructed.

[Citation List] [Patent Literature]

[0005]

[Patent Literature 1 ]

Japanese Unexamined Patent Application, First Publication No. 2001-90060

[Patent Literature 2]

Japanese Unexamined Patent Application, First Publication No. 2012-237138

[Summary of Invention]

[Technical Problem]

[0006]

Incidentally, although bentonite fluid is pumped up and reprocessed during construction of a continuous, the bentonite generated by reprocessing has adverse effects on the environment when it is discarded as an industrial waste.

The methods for constructing a continuous underground wall described in Patent

Literatures 1 and 2 require a casing, spiral agitating members, or the like in addition to a steel pipe and the number of working operations is large. Thus, there is a drawback that much effort is needed and the construction costs are high.

[0007]

For this reason, the present invention was made in view of the above-described circumstances and an object of the present invention is to provide a method for constructing a continuous underground wall and a steel pipe pile used for the

construction method which do not produce industrial waste accompanying processing, do not involve a pile body with a double structure, and can be constructed with a small number of working operations and the low construction costs.

[Solution to Problem]

[0008] A method for constructing a continuous underground wall according to the present invention includes: a steel pipe installation step of continuously alternately installing first steel pipes and second steel pipes in a construction direction; an excavation step of excavating a content in each of the first steel pipes and the second steel pipes while the first steel pipes and the second steel pipes are being installed or after the first steel pipes and the second steel pipes have been installed; a first solidification material-filling step of pulling out the first steel pipes when the first steel pipes arranged as every other steel pipe are being filled with a solidifying material or after the first steel pipes have been filled with a solidifying material; and a second solidification

material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material-filling step is being disturbed using claws protruding outside of the second steel pipe while the second steel pipe arranged between the first steel pipes is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

According to the present invention, it is possible to form a continuous underground wall in which the piles made of a solidifying material are joined by pulling out the second steel pipe from the solidifying material between the piles made of the solidifying material in which the first steel pipe is pulled out from the first steel pipe and the second steel pipe which are continuously installed while the solidifying material is disturbed using the claws in the second steel pipe. For this reason, it is possible to construct a continuous underground wall in which the piles made of a solidifying material are integrated with a small number of steps. Moreover, it is possible to prevent collapse of the solidifying material at the time of construction and to prevent the production of industrial waste because bentonite or the like is not used.

[0009] A method for constructing a continuous underground wall according to the present invention includes: a first steel pipe installation step of installing first steel pipes at intervals in a construction direction; a first excavation step of excavating a content in each of the first steel pipes while the first steel pipe is being installed or after the first steel pipe has been installed; a first solidification material-filling step of pulling out the first steel pipe while the first steel pipe is being filled with a solidifying material or after the first steel pipe has been filled with a solidifying material; a second steel pipe installation step of installing the second steel pipe between the first steel pipes; a second excavation step of excavating the content in each of the second steel pipes while the second steel pipe is being installed or after the second steel pipe has been installed; and a second solidification material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material-filling step is being disturbed using claws protruding to the outside of the second steel pipe while the second steel pipe is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

According to the present invention, it is possible to form the continuous underground wall in which the piles made of the solidifying material are connected by pulling out the second steel pipe from the solidifying material while the solidifying material is being disturbed using the claws in the subsequently installed second steel pipe between the piles made of the solidifying material in which the previously installed first steel pipe is pulled out.

[0010]

A method for constructing a continuous underground wall according to the present invention includes: a second steel pipe installation step of installing second steel pipes at intervals in a construction direction; a second excavation step of excavating the content in each of the second steel pipes while the second steel pipe is being installed or after the second steel pipe has been installed; a first steel pipe installation step of installing a first steel pipe between the second steel pipes; a first excavation step of excavating the contents of the first steel pipes while the first steel pipe is being installed or after the first steel pipe has been installed; a first solidification material-filling step of pulling out the first steel pipe while the first steel pipe is being filled with a solidifying material or after the first steel pipe has been filled with a solidifying material; and a second solidification material-filling step of pulling out the second steel pipe while the solidifying material filled in the first solidification material -filling step is being disturbed using claws protruding to the outside of the second steel pipe while the second steel pipe is being filled with a solidifying material or after the second steel pipe has been filled with a solidifying material.

According to the present invention, it is possible to form the continuous underground wall in which the piles made of the solidifying material are joined by installing the first steel pipe between the previously installed second steel pipes having the claws and pulling out the second steel pipe from the solidifying material while the solidifying material is being disturbed using the claws in the second steel pipe between the piles made of the solidifying material in which the first steel pipe is pulled out.

[0011]

It is also desirable that the claws be in positions in which the claws do not interfere with the first steel pipe when the second steel pipe is installed.

It is possible to install the claws at positions in which the claws do not interfere with the first steel pipe when the second steel pipe is installed with respect to the previous installed first steel pipe through press-in, swingable press-in, or the like.

[0012] It is desirable that the claws in the second steel pipe be provided in a gap between a circumscribing line of one of the first steel pipe and/or the second steel pipe or two opposite circumscribing lines of both of the first steel pipe and/or the second steel pipe and an adjacent first steel pipe.

It is possible to install the second steel pipe by locating the claws between the circumscribing line and the neighboring first steel pipe even when the continuous underground wall is constructed in a position close to an already installed construction.

[0013]

The second steel pipe on which the claws are provided may be installed through press-in, rotational press-in, or swingable press-in.

The second steel pipe can be installed by selecting any of press-in, rotational press-in, or swingable press-in so that the claws do not interfere with the second steel pipe in the hardness of the ground or a relationship with the first steel pipe.

[0014]

It is desirable that the solidifying material filled in the first solidification material-filling step be in a state of being between a solidification start time and a solidification termination time when the second steel pipe is pulled out.

The solidifying material filled in the first solidification material-filling step flows when the solidifying material is disturbed using the claws in the second steel pipe if the solidifying material is in a state being between the solidification start time and the solidification termination time, is agitated together with the solidifying material filled in the second solidification material-filling step, and is integrated with the solidifying material filled in the second solidification material-filling step.

[0015]

It is desirable that the claws in the second steel pipe be expandable and contractible outward.

It is possible to smoothly press-drive the second steel pipe because the previously installed first steel pipe does not interfere with the claws and the second steel pipe is press-driven by contracting the claws when the second steel pipe is installed. Furthermore, it is possible to disturb and integrate the solidifying material of the first steel pipe by expanding the claws when the second steel pipe is pulled out.

[0016]

It is desirable that there be replenishment with new solidifying material while the solidifying material filled in the first solidification material-filling step is being disturbed using the claws when the second steel pipe is pulled out.

It is possible to reinforce the joining portion between the solidifying materials by replenishing the solidifying material disturbed using the claws in the second steel pipe with new solidifying material and thus to help the integration.

[0017]

A press-in machine may be installed in the first steel pipe and/or the second steel pipe and the press-in machine may install and pull out the first steel pipe and the second steel pipe.

It is possible to perform press-in and pulling-out by generating a reaction force in the first steel pipe or the second steel pipe by installing the press-in machine above the first steel pipe or the second steel pipe, and it is possible to move above the first steel pipe or the second steel pipe which has been installed without generating a footpath in the surrounding ground. Thus, it is possible to perform construction even in inclined or uneven terrain.

[0018]

PC steel wires may be installed in the excavated first steel pipe and/or second steel pipe, a first solidifying material corresponding to the first steel pipe and/or a second solidifying material corresponding to the second steel pipe may be fixed and then the PC steel wires may be tensioned and a prestress may be introduced.

It is possible to control the tensile stress exerted on the continuous underground wall when a prestress is introduced to the first pile and/or the second pile constituting the continuous underground wall using a post-tension method.

[0019]

The first steel pipe and the second steel pipe may be pulled out and the first solidifying material and the second solidifying material may be disturbed using the claws in a ground region, and the first steel pipe and the second steel pipe may be held without being pulled out in water.

Since the solidifying materials filled in the first steel pipe and the second steel pipe are not in direct contact with water, the solidifying materials can be held in a self-standing state.

The first steel pipe and the second steel pipe may be pulled out and the first solidifying material and the second solidifying material may be disturbed using the claws in a ground region, and the first steel pipe and the second steel pipe may be held without being pulled out above the ground.

The solidifying materials filled in the first steel pipe and the second steel pipe can be held in a self-standing state using the first steel pipe and the second steel pipe above the ground.

[0020]

A steel pipe pile according to the present invention includes: a steel pipe; and claws protruding outward in a radial direction from a suitable position on the steel pipe in a longitudinal direction, wherein adjacent solidifying material is disturbed using the claws when the steel pipe installed in the ground is pulled up.

According to the present invention, it is possible to fill the installed steel pipe with a solidifying material and the solidifying material and a neighboring solidifying material can be integrated by the neighboring solidifying material being disturbed using the claws when the steel pipe is pulled up.

[Advantageous Effects of Invention]

[0021]

According to the method for constructing the continuous underground wall of the present invention, it is possible to form the continuous underground wall in which the pile bodies are joined by pulling out the second steel pipe while the pile bodies are disturbed using the claws in the second steel pipe between the piles made of the solidifying material in which the first steel pipe is pulled out. For this reason, it is possible to reliably construct the continuous underground wall in which the pile bodies made of the solidifying material are integrated with a small number of steps.

Moreover, it is possible to prevent collapse of the solidifying material at the time of constructing, to prevent the production of industrial waste and to reduce the number of parts and the number of working operations because bentonite or the like is not used.

[0022]

According to the steel pipe pile of the present invention, it is possible to disturb and integrate neighboring pile bodies made of the solidifying material at the time of pulling out because claws are formed on the outer circumferential surface of the steel pipe pile.

[Brief Description of Drawings]

[0023]

Fig. 1 A is a diagram showing a first steel pipe used in a method for constructing a continuous underground wall according to an embodiment of the present invention.

Fig. IB is a diagram showing a second steel pipe used in the method for constructing the continuous underground wall according to the embodiment of the present invention.

Fig. 2A is a plan view showing the second steel pipe.

Fig. 2B is a partial side view showing the second steel pipe.

Fig. 3 A is a plan view showing an arrangement of the first steel pipe and the second steel pipe buried in the ground.

Fig. 3B is a side view of a main part showing an arrangement of the first steel pipe and the second steel pipe buried in the ground.

Fig. 3 C is an explanatory diagram showing a claw of the second steel pipe and showing an arrangement of the first steel pipe and the second steel pipe buried in the ground.

Fig. 4A is an explanatory diagram of a step of pulling out the first steel pipe from an underground wall body in a method for constructing a continuous underground wall according to a first embodiment.

Fig. 4B is a structural view of the method for constructing the continuous underground wall according to the first embodiment.

Fig. 5A is an explanatory diagram of a step of pulling out another first steel pipe and a structural view thereof.

Fig. 5B is an explanatory diagram of a step of pulling out the other first steel pipe and a structural view thereof.

Fig. 6A is an explanatory diagram of a step of pulling out the second steel pipe and a structural view thereof.

Fig. 6B is an explanatory diagram of a step of pulling out the second steel pipe and a structural view thereof.

Fig. 7A is an explanatory diagram of a step of pulling out another second steel pipe and a structural view thereof.

Fig. 7B is an explanatory diagram of a step of pulling out the other second steel pipe and a structural view thereof.

Fig. 8 A is an explanatory diagram of a step of constructing a continuous underground wall.

Fig. 8B is an explanatory diagram showing a disposition of a first pile and a second pile.

Fig. 8C is a diagram showing a modified example of a first pile.

Fig. 9A is a plan view illustrating a first modified example of a claw provided in the second steel pipe.

Fig. 9B is a plan view showing the claw and a partial cross-sectional view taken along line A-A in Fig. 9A.

Fig. 10 is an explanatory diagram of a step of pulling out a first steel pipe from a wall body in a method for constructing a continuous underground wall according to a second embodiment.

Fig. 11 is an explanatory diagram of a step of pulling out another first steel pipe.

Fig. 12 is an explanatory diagram of a step of pulling out a second steel pipe.

Fig. 13 is an explanatory diagram of a step of pulling out another second steel pipe.

Fig. 14 is an explanatory diagram of a step of installing a second steel pipe in a method for constructing a continuous underground wall according to a third embodiment.

Fig. 15 is a diagram showing a step of pulling out a first steel pipe.

Fig. 16 is a diagram showing a step of pulling out another first steel pipe. Fig. 17 is a diagram showing a step of pulling out a second steel pipe.

Fig. 18 is a diagram showing a modified example of a wall body and a claw.

Fig. 19A is a plan view showing a second modified example of a claw provided in the second steel pipe.

Fig. 19B is a longitudinal cross-sectional view showing a second modified example of the claw provided in the second steel pipe.

Fig. 19C is a rear view of the claw showing the second modified example of the claw provided in the second steel pipe.

Fig. 20 is an exploded perspective view of the claw.

Fig. 21 A is an explanatory diagram of wall bodies of a first steel pipe and a second steel pipe indicating a continuous underground wall according to a modified example.

Fig. 21B is an explanatory diagram of the continuous underground wall according to the modified example.

Fig. 22 is an explanatory diagram showing a part of a continuous underground wall according to a modified example, in which a prestress unit is installed in a first steel pipe.

Fig. 23 is a diagram showing a first pile filled with concrete.

Fig. 24 is a diagram showing the first pile of a continuous underground wall to which a prestress is exerted.

Fig. 25 is a diagram showing a modified example of a method for constructing a continuous underground wall.

Fig. 26 is a cross-sectional view of a main part showing a modified example of the continuous underground wall.

[Description of Embodiments] [0024]

A method for constructing a continuous underground wall according to an embodiment of the present invention and a second steel pipe 2 used in the constructing method will be described below with reference to the accompanying drawings.

Figs. 1 to 8 are diagrams showing a method for constructing a continuous underground wall R according to a first embodiment of the present invention. In the first embodiment, a continuous underground wall R is constructed using a first steel pipe 1 and a second steel pipe 2. The first steel pipe 1 is a conventional steel pipe shown in Fig. 1 A, and as shown in Fig. IB, the second steel pipe 2 includes a pair of claws 3 protruding outward in a radial direction from opposite positions on a pipe body on an outer circumferential surface thereof at a lower portion in a longitudinal direction thereof.

The first steel pipe 1 and the second steel pipe 2 constitute a steel pipe pile.

[0025]

Each of the claws 3 of the second steel pipe 2 is made of, for example, steel as shown in Figs. 2A and 2B and is formed in a substantially circular-arc-shaped plate shape and a distal end 3a is formed in a circular arc shape. Blades 4 made of a high hardness material, for example, cemented carbide, are joined to both sides 3b of the claw 3 and cross sections of the distal end 3 a of the claw 3 and the blades 4 on both ends thereof in a circumferential direction thereof have, for example, a substantially triangular shape.

For this reason, when the second steel pipe 2 is press-driven into the ground, the ground can be excavated by performing linear press-in, rotational press-in, or swingable press-in using the distal end 3 a of the claw 3 and the blades 4 on both sides thereof.

When pulling out the second steel pipe 2 from the ground, adjacent first piles made of concrete before hardening can be disturbed and integrated using the distal ends 3 a and the blades 4 of the claws 3. Each of the claws 3 can be installed at a suitable position of the second steel pipe 2 in the longitudinal direction thereof if necessary.

[0026]

A method for constructing a continuous underground wall R according to the first embodiment will be described below on the basis of steps shown in Figs. 3 to 7.

First, the first steel pipe 1 and the second steel pipe 2 are alternately press-driven and sequentially installed using, for example, a press-in machine 6 shown in Fig. 4 as a press-in and pulling-out device (steel pipe installation step). Figs. 3 A to 3 C show a wall body 7 of first steel pipes 1 and second steel pipes 2 continuously press-driven into the ground and each of the second steel pipes 2 is installed between the first steel pipes 1.

In the steel pipe installation step, the second steel pipe 2 is swung in a range in which the claws 3 do not interfere with the first steel pipe 1 which has been previously press-driven such that it is linearly press-driven without being swingably press-driven or swung.

[0027]

A method for constructing a continuous underground wall by pulling out the first and second steel pipes 1 and 2 from the wall body 7 will be described below with reference to Figs. 4 to 7, and Figs. 4A, 5 A, 6A, and 7A in the drawings illustrate construction steps and Figs. 4B, 5B, 6B, and 7B illustrate a constitution of the wall body 7 in each step.

In Fig. 4, the press-in machine 6 generates a reaction force by installing a lock portion of a platform vehicle 8 in the first steel pipe 1 and the second steel pipe 2 which has been previously installed (or a reaction force weight), grips each of the steel pipes 1 and 2 using a gripping portion 9, and pulls out the steel pipe from the ground while the steel pipe is being filled with concrete or after the steel pipe has been filled with concrete. It is desirable that the press-in machine 6 cause the plurality of first steel pipes 1 and second steel pipes 2 which form the wall body 7 to project by a height from a surface of the ground GL by which the lock portion can be clamped. Thus, the press-in machine 6 press-drives and pulls out the first steel pipes 1 and the second steel pipe 2 while moving above the first steel pipes 1 and the second steel pipes 2.

[0028]

In Fig. 4A, after the content in each of the steel pipes 1 and 2 has been press-driven by the press-in machine 6 (or while the contents in each of the steel pipes 1 and 2 is being press-driven), earth and sand are discharged from each of the steel pipes 1 and 2 using an excavator (not shown) (excavation step). Subsequently, while the first steel pipe 1 press-driven at an end of the wall body 7 is being filled with concrete or after the first steel pipe 1 has been filled with concrete, the press-in machine 6 pulls out another first steel pipe 1 which has been installed while generating a reaction force in the other first steel pipe 1 (first solidification material-filling step). Thus, a substantially circular columnar first pile 1 A made of concrete is buried in the ground. The first pile 1 A is unhardened but supported by the surrounding ground.

Since the first steel pipe 1 is pulled out while being filled with concrete, collapse of the hole in the ground does not occur. In Fig. 4, the GL surface of the ground is an upper surface of the first pile 1 Aa (1 A).

[0029]

Subsequently, the press-in machine 6 is moved above another first steel pipe 1 which is open. While adjacent first steel pipes 1 which sandwich the second steel pipe 2 with respect to the first pile 1 Aa are being filled with concrete or after adjacent first steel pipes 1 have been filled with concrete, the press-in machine 6 pulls out the first steel pipe 1 (second solidification material-filling step). The press-in machine 6 pulls out the first steel pipe 1 while generating a reaction force in another first steel pipe 1.

Since it is difficult to grip a first steel pipe 1 between second steel pipes 2 when the first steel pipe 1 is pulled out as shown in Fig. 5 A, a pressing and hardening device 11 is gripped by the gripping portion 9 in the press-in machine 6, a distal end of the pressing and hardening device 11 is fitted into and engaged with the first steel pipe 1 , and the first steel pipe 1 is pulled out. In this way, the substantially circular columnar first pile 1 Ab made of concrete is buried in the ground.

[0030]

Subsequently, in Fig. 6, while a second steel pipe 2 between first piles 1 Aa and 1 Ab is being filled with concrete or after the second steel pipe 2 has been filled with concrete, the press-in machine 6 pulls out the second steel pipe 2 while generating a reaction force in another second steel pipe 2. At this time, the first piles 1 Aa and 1 Ab are unhardened and the second steel pipe 2 is linearly pulled out while the second steel pipe 2 is being swung in a state in which the second steel pipe 2 is rotated and overlaps the first piles 1 Aa and 1 Ab or without swinging the second steel pipe 2.

Thus, a substantially circular columnar second pile 2Aa made of concrete is buried in the ground in a state in which the second pile 2Aa is unhardened. Moreover, the unhardened first piles 1 Aa and 1 Ab are disturbed by the opposite claws 3 of the second steel pipe 2 and are integrated with the second pile 2Aa (2A).

[0031]

Here, since an increased amount of concrete is supplied through the second steel pipe 2 to be pulled out when the first piles 1 Aa and 1 Ab on both sides are disturbed using the claws 3 of the second steel pipe 2 and are integrated with the second pile 2Aa of the second steel pipe 2, cross-sectional areas of joining portions of the second pile 2Aa to the first piles 1 Aa and 1 Ab increase. Thus, the joining portions between the second pile 2Aa and the first piles lAa and 1 Ab on both sides thereof are replenished with concrete and a high-strength continuous underground wall R is formed. In the example shown in Fig. 7, the second pile 2Aa is formed to have a large width at the joining portions on both sides thereof to the first piles 1 Aa and 1 Ab.

[0032]

Subsequently, the press-in machine 6 skips one second steel pipe 2 which has been buried and is moved from the first pile 1 Ab to a first steel pipe 1. The press-in machine 6 pulls out the first steel pipe 1 while the first steel pipe 1 is being filled with concrete or after the first steel pipe 1 has been filled with concrete. The press-in machine 6 pulls out the first steel pipe 1 while generating a reaction force in another first steel pipe 1 and the first pile 1 Ac made of concrete is maintained in a state in which the first pile 1 Ac is buried.

In this state, as shown in Fig. 7A, the press-in machine 6 pulls out the second steel pipe 2 while the second steel pipe 2 between the first piles 1 Ab and 1 Ac is being filled with concrete or after the second steel pipe 2 has been filled with concrete. At that time, the first piles 1 Ab and 1 Ac are unhardened and the second steel pipe 2 is linearly pulled out while the second steel pipe 2 is being swung in a state in which the second steel pipe 2 is rotated and the claws 3 overlap the first piles lAb and 1 Ac or without swinging the second steel pipe 2. Thus, a substantially circular columnar second pile 2Ab made of concrete is buried in the ground in a state in which the second pile 2Ab is unhardened. Moreover, since the unhardened first piles 1 Ab and lAc are disturbed by the opposite claws 3 of the second steel pipe 2 and are unhardened, joining portions thereof to the second pile 2Ab are reinforced and integrated by replenishing concrete. Moreover, as shown in Figs. 7A and 7B, a width of the second pile 2Ab increases. [0033]

By repeating such work, in the wall body 7, the first pile 1 A and a second pile 2A made of concrete are alternately arranged. Moreover, since the first piles 1 A (= 1 Aa, lAb, 1 Ac, ...) are disturbed by the claws 3 of the second steel pipe 2, as shown in Figs. 8A and 8B, the first piles 1 A and the second piles 2A (= 2Aa, 2Ab, ...) are integrated in the ground and a continuous underground wall R in which diameters of joining portions of the second piles 2A to the first piles 1 A are increased is formed.

It should be noted that H steel may be used in the first piles 1 A or the second piles 2A in accordance with a required wall strength for the continuous underground wall R (refer to Fig. 8C).

[0034]

As described above, according to the method for constructing the continuous underground wall R of the first embodiment, since the opposite claws 3 are provided on the second steel pipe 2 press-driven between the first steel pipes 1, the continuous underground wall R in which the first piles 1 A and the second piles 2 A are integrated can be formed by sequentially repeating steps of pulling out the second steel pipe 2 filled with concrete between the first piles 1 A and 1 A made of concrete. For this reason, the construction is simple and costs can be reduced.

Moreover, since the second steel pipe 2 is replenished with concrete when the second steel pipe 2 is pulled out, it is possible to form a high-strength continuous underground wall R and to improve waterproofing by reinforcing the concrete of the - joining portions between the second pile 2 A and the first piles 1 A on both sides thereof.

[0035]

Note that the method for constructing the continuous underground wall R according to the present invention and the second steel pipe 2 used for the method are not limited to the above-described embodiments and various modifications and substitutions are possible without departing from the gist of the present invention. In addition, these cases are also included in the technical scope of the present invention. Hereinafter, portions and constituent elements of other embodiments or modified examples of the present invention that are the same as or similar to those of the above-described embodiments will be denoted with the same reference numerals and description thereof will not be provided.

[0036]

Fig. 9 illustrates a first modified example of the claws 3 installed on the second steel pipe 2.

In claws 13 according to this modified example, as shown in Fig. 9 A, for example, blades 14 made of cemented carbide may be fixed to distal ends 13a at predetermined intervals. In each of the blades 14, as shown in Fig. 9B, an acute angle blade 14a protruding from an upper side thereof is formed. Thus, when the second steel pipe 2 is pulled out, the first piles 1A on both sides can be cut and disturbed.

As another modified example, a constitution in which the blades 14 of the claws

13 shown in Fig. 9 are added to the distal ends 3a of the claws 3 shown in Fig. 2 may be adopted. When such a constitution is adopted, the strength and the cutting ability of the claws 3 are further increased and the effects of disturbing an unhardened or

semi-hardened first pile 1 A are improved. Furthermore, materials of the blades 4 and

14 are not limited to cemented carbide and appropriate high-strength alloys such as cBN can be adopted.

[0037]

Next, a method for constructing a continuous underground wall R according to a second embodiment of the present invention will be described with reference to Figs. 10 to 13.

In Fig. 10, as a first steel pipe installation step, a press-in machine 6 press-drives first steel pipes 1 at intervals of one second steel pipe 2 in a construction direction of a wall body 7. Each of the first steel pipes 1 may be installed by any of press-in, rotational press-in, and swingable press-in. Next, as a first excavation step, an excavator (not shown) excavates the contents in the first steel pipe 1 while the first steel pipe 1 is being installed or after the first steel pipe 1 has been installed.

In a first solidification material-filling step, the first steel pipe 1 is pulled out while the first steel pipe 1 is being filled with a solidifying material such as concrete or after the first steel pipe 1 has been filled with a solidifying material. When the first steel pipe 1 is pulled out, a substantially circular columnar first pile 1 Aa made of concrete is buried in the ground in a state in which the first pile 1 Aa is unhardened.

[0038]

As shown in Fig. 11, the first steel pipe 1 is pulled out at a neighboring position spaced apart from the first pile 1 Aa while the first steel pipe 1 is being filled with a solidifying material such as concrete or after the first steel pipe 1 has been filled with a solidifying material. When the first steel pipe 1 is pulled out, a substantially circular columnar first pile 1 Ab made of concrete is buried in the ground in a state in which the first pile 1 Ab is unhardened.

Subsequently, as a second steel pipe installation step, the press-in machine 6 press-drives the second steel pipe 2 between the first piles 1 Aa and 1 Ab. Since a pair of claws 3 (or claws 13) are fixed at opposite positions on a lower end of the second steel pipe 2, the second steel pipe 2 is installed not to interfere with the first piles 1 Aa and 1 Ab through press-in or swingable press-in. As a second excavation step, an excavator (not shown) excavates and discharges the contents in the second steel pipe 2 while the second steel pipe 2 is being installed or after the second steel pipe 2 has been installed.

[0039]

Subsequently, as a second solidification material-filling step, as shown in Fig. 12, the press-in machine 6 pulls out the second steel pipe 2 while the second steel pipe 2 which has been buried in the ground is being filled with concrete or after the second steel pipe 2 has been filled with concrete. Thus, a second pile 2Aa made of concrete is buried in the ground. When the second steel pipe 2 is pulled out, the second steel pipe 2 is pulled out while the first piles 1 Aa and 1 Ab on both sides are being disturbed by the claws 3 protruding outside of the second steel pipe 2. Moreover, when the second steel pipe 2 is pulled out, additional concrete is replenished through the second steel pipe 2.

At that time, the first piles 1 Aa and 1 Ab are unhardened and the second steel pipe 2 is linearly pulled out while the second steel pipe 2 is being swung in a state in which the second steel pipe 2 is rotated and the claws 3 overlap the first piles 1 Ab and 1 Ac or without swinging the second steel pipe 2. Thus, the substantially circular columnar second pile 2Aa made of concrete is buried in the ground in a state the second pile 2Aa is unhardened. Moreover, since the unhardened first piles 1 Aa and 1 Ab are disturbed by the opposite claws 3 of the second steel pipe 2, the unhardened first piles lAa and lAb are integrated with the second pile 2Aa and diameters of joining portions of the second pile 2Aa are increased due to additional concrete.

[0040]

By repeating such work, the second pile 2A in which the second steel pipe 2 is pulled out is joined between the first piles 1 A and 1 A in which the first steel pipe 1 is pulled out. Moreover, since the unhardened first pile 1 A is disturbed using the claw 3 of the second steel pipe 2 and is replenished with additional concrete, as shown in Fig. 13, the continuous underground wall R is formed in which the diameters of the joining portions of the second pile 2 A to the first piles 1 A on both sides thereof are enlarged. The second solidification material-filling step for the second steel pipe 2 is performed in a step in which the first piles 1 A and 1 A which have been previously installed are unhardened. For this reason, the number of first piles 1 A which can be installed until the process reaches the second solidification material-filling step is limited and these construction steps are repeatedly performed.

Also in the second embodiment, it is possible to construct a high-strength continuous underground wall R and reduce the number of construction steps and the construction costs.

[0041]

A method for constructing a continuous underground wall R according to a third embodiment of the present invention will be described below on the basis of steps shown in Figs. 14 to 17. In this embodiment, the continuous underground wall R is constructed above the hard ground and a second steel pipe 2 having claws 3 installed thereon is buried in the hard ground through rotational press-in. For this reason, the second steel pipe 2 is first press-driven and then the first steel pipe 1 is press-driven.

In a second steel pipe installation step shown in Fig. 14, second steel pipes 2 are buried in the ground at intervals through rotational press-in in a construction direction of a wall body 7 using a press-in machine 6. As a second excavation step, an excavator excavates and discharges the contents in the second steel pipe 2 while the second steel pipe 2 is being installed or after the second steel pipe 2 has been installed.

Subsequently, in Fig. 15, as a first steel pipe installation step, the first steel pipe 1 is press-driven between the buried second steel pipes 2. Press-in for the first steel pipe 1 may be any of press-in, rotational press-in, and swingable press-in. The contents of the first steel pipe 2 is excavated while the first steel pipe 1 is being installed or after the first steel pipe 1 has been installed.

[0042]

In a first solidification material-filling step in Fig. 15, the press-in machine 6 pulls out the first steel pipe 1 while the first steel pipe 1 is being filled with concrete or after the first steel pipe 1 has been filled with concrete. A substantially circular columnar first pile 1 Aa made of concrete is buried in the ground by pulling out the first steel pipe 1. Furthermore, in Fig. 16, the press-in machine 6 pulls out the first steel pipe 1 while a first steel pipe 1 after the second steel pipe 2 has been skipped after the first pile 1 Aa is being filled with concrete or the first steel pipe 1 has been filled with concrete. A substantially circular columnar first pile 1 Ab made of concrete is buried in the ground by pulling out the first steel pipe 1.

In a second solidification material-filling step shown in Fig. 17, the press-in machine 6 pulls out the second steel pipe 2 while the second steel pipe 2 press-driven between the first piles 1 Aa and 1 Ab is being filled with concrete or after the second steel pipe 2 has been filled with concrete. Thus, a second pile 2 Aa made of concrete is buried in the ground.

[0043]

When the second steel pipe 2 is pulled out, the second steel pipe 2 is pulled out while the first piles 1 Aa and 1 Ab on both sides are being disturbed using the claws 3 protruding outside of the second steel pipe 2. When the second steel pipe 2 is pulled out, the second steel pipe 2 is pulled out in a state in which the claws 3 are not swung to overlap the first piles 1 Aa and 1 Ab or while the second steel pipe 2 is being swung.

Thus, the substantially circular columnar second pile 2Aa made of concrete is buried in the ground in a state in which second pile 2Aa is unhardened.

Moreover, the unhardened first piles 1 Aa and 1 Ab are disturbed using the claws 3 of the second steel pipe 2 and are integrated with the unhardened second pile 2Aa. In addition, diameters of joining portions of the second pile 2Aa are increased due to replenishing concrete.

[0044]

By repeating such work, the second pile 2A in which the second steel pipe 2 is pulled out is buried between the first piles 1 A and 1 A in which the first steel pipe 1 is pulled out and the first piles 1 A and the second pile 2 A which are made of concrete are alternately arranged. Since the unhardened first piles 1 A are disturbed using the claws 3 of the second steel pipe 2, the unhardened first piles 1 A are integrated in the ground. In addition, as shown in Fig. 17, a continuous underground wall R is formed in which diameters of joining portions of the second pile 2 A to the first piles 1 A on both sides thereof are increased due to additional replenishing concrete.

Also in the third embodiment, it is possible to construct a high-strength continuous underground wall R and to reduce the number of construction steps and the construction costs.

[0045]

When the continuous underground wall R is constructed, other existing structures may be installed in neighboring places in some cases. In this case, as shown in Fig. 18, construction needs to be performed so that the claws 3 of the second steel pipe 2 do not protrude outside of a circumscribing line L serving as a tangent on one outer side of the wall body 7 constituted of the first steel pipes 1 and the second steel pipes 2 (the first piles 1 A and the second piles 2 A) arranged in the construction direction thereof. In this case, construction can be performed so that the claws 3 do not protrude outside of the circumscribing line L by press-in the second steel pipe 2 or swingable press-in the second steel pipe 2 within a range of a gap between the circumscribing line L and an adjacent first steel pipe 1. In this case, the claws 3 may be adopted as long as the claws 3 are formed, for example, in a substantially triangular plate shape whose sides form convex curves.

An existing structure may be constructed on one side of the wall body 7 as well as the other side thereof opposite thereto. Construction can be performed so that the claws 3 do not protrude outside of circumscribing lines L and La by press-in the second steel pipe 2 in a region sandwiched by these circumscribing lines L and La or swingable press-in the second steel pipe 2 within ranges of gaps between the circumscribing lines L and La on both sides and adjacent first steel pipes 1.

[0046]

It should be noted that, although the claws 3 are fixedly arranged on the second steel pipe 2 to be opposite to each other in the above-described embodiments and modified example, the claws 3 serve as resistances when the second steel pipe 2 is press-driven into the ground in this case. Thus, construction is performed through rotational press-in or swingable press-in in some cases.

On the other hand, in a second modified example, claws 16 are installed to be expandable and contractible or advanceable and retractable. One example of the expandable and contractible claws 16 will be described below with reference to Figs. 19 and 20. The expandable and contractible claws 16 according to the second modified example are installed to be opposite to each other on opposite positions on a lower end of a second steel pipe 2 shown in Fig. 19. Each of the claws 16 includes a bearing part 17 fixed to an outer circumferential surface of the second steel pipe 2, a support shaft 18 inserted into a through-hole of the bearing part 17, and a claw main body 19 to which both ends of the support shaft 18 are fitted and which can rotate in an upward/downward direction about the support shaft 18. [0047]

As shown in Fig. 20, the claw main body 19 has a plate shape which forms a concave curved surface along the outer circumferential surface of the second steel pipe 2, a concave part 19a to which the bearing part 17 can be fitted is formed in a base portion thereof, and a distal end 19b which forms a blade is a convex curved surface or an inclined surface which is inclined in a thickness direction. Holes through which the support shaft 18 is fitted are formed in both side surfaces in the concave part 19a. Ends of the concave part 19a on both sides thereof are stopper parts 19c. In addition, the claw main body 19 opens in a horizontal position so that the claw main body 19 can come into contact with the outer circumferential surface of the second steel pipe 2 and receive a disturbing load at the time of pulling out.

[0048]

The claw main body 19 is held in an erected position in which the concave curved surface is in contact with the outer circumferential surface of the second steel pipe 2 in a normal state, and in this state, the distal end 19b forms a pocket P which is curved or inclined upward as it separates from the outer circumferential surface of the second steel pipe 2 in a thickness direction thereof. Concrete or the like of the first pile 1 A flows into the pocket P of the distal end 19b when the second steel pipe 2 buried in the ground is pulled out. Thus, the claw main body 19 opens outward about the support shaft 18 and thus a diameter of the claw main body 19 is increased at a substantially horizontal position so that the first pile 1 A can be excavated and disturbed.

On the other hand, when the second steel pipe 2 is press-driven, the claw main body 19 is held with a reduced diameter in which the claw main body 19 is erected and is in contact with an outer circumferential surface and does not interfere with press-in. For this reason, the second steel pipe 2 can be linearly press-driven as well as rotationally press-driven and swingably press-driven.

[0049]

In the above-described embodiments, the claws 3, 13, and 16 are installed in the vicinity of the lower end of the second steel pipe 2 and a continuous underground wall R which can be waterproof and has a wall body strength over substantially the entire length is constructed. However, for example, if the continuous underground wall R is for the purpose of being waterproof rather than having wall body strength, the claws 3 or the claws 16 may be installed in a range for wateφroofing. A method for constructing the continuous underground wall R according to the above-described modified example will be described with reference to Fig. 21.

In Fig. 21 A, for example, when a clay layer is present in the ground and groundwater flows above the clay layer, in order to provide a waterproof function with respect to the groundwater, a continuous wall body Rl may be constructed above the clay layer. For this reason, the claws 3 are installed in an intermediate position of the second steel pipe 2 in a longitudinal direction corresponding to the clay layer.

[0050]

In this modified example, for example, the first steel pipe 1 is pulled out while the installed first steel pipe 1 is being filled with concrete or after the installed first steel pipe 1 has been filled with concrete and the first piles 1 Aa and 1 Ab are sequentially constructed. Subsequently, when the second steel pipe 2 is pulled out while the second steel pipe 2 between the first piles 1 Aa and 1 Ab is being filled with concrete or after the second steel pipe 2 has been filled with concrete, concrete of the first piles 1 Aa and 1 Ab is disturbed on an upper side from a portion in which the claws 3 are provided, a width of the second pile 2Aa toward both sides thereof is increased by further adding replenishing concrete, and the second pile 2Aa is integrated with the first piles 1 Aa and 1 Ab. A continuous wall body Rl shown in Fig. 21 B is formed in a range for waterproofing by sequentially performing such work.

In this case, an earth pressure can be supported by the bending strength of the first pile 1 A and the second pile 2A themselves even when the first pile 1 A and the second pile 2 A of the continuous wall body Rl on a lower side thereof are not connected to each other and thus it is possible to secure the wall body strength of the continuous underground wall R. Moreover, it may be unnecessary to disturb the first pile 1 A through the excavation on a side below the claws 3 and thus construction is faster and the material costs of concrete or the like can be reduced.

[0051]

A prestress may be introduced to a first pile 1 A and a second pile 2 A in a continuous underground wall R through a post-tension method. Although this modified example will be described with reference to Figs. 22 to 24, only a first steel pipe 1 and a first pile 1 A corresponding thereto are shown in the drawings and other first steel pipes 1 and a first pile 1 A and a second pile 2 A corresponding to other first steel pipe 1 and second steel pipe 2 are omitted.

As in the above-described embodiments, the first steel pipe 1 and the second steel pipe 2 are installed in the ground, and the contents in the first steel pipe 1 and the second steel pipe 2 are excavated and discharged. A prestress unit 21 is installed in the first steel pipe 1 shown in Fig. 22. In the prestress unit 21, sheath tubes 24 having prestressed concrete (PC) steel wires 23 built thereinto are installed on one surface of an end plate 22 and the PC steel wires 23 pass through the other surface of the end plate 22 and are fixed using fixing tools 25. In the prestress unit 21, the end plate 22 is installed at a lower end of the first steel pipe 1 from which the earth is discharged and the PC steel wires 23 and the sheath tubes 24 pass inside the first steel pipe 1 and extend from an upper opening to the outside.

[0052]

Moreover, through steps that are the same as those in the above-described embodiments, as shown in Fig. 23, a press-in machine 6 pulls out the first steel pipe 1 from the ground while the first steel pipe 1 is being filled with concrete or after the first steel pipe 1 has been filled with concrete and the first piles 1 A are generated. When the second steel pipe 2 is pulled out while the first steel pipe 1 is being filled with concrete or after the first steel pipe 1 has been filled with concrete, the first piles 1 A provided on both sides thereof are disturbed using claws 3 and thus the first piles 1 A are integrated with the second pile 2 A. Subsequently, after the first pile 1 A is cured and exhibits a predetermined strength, a lid 26 is installed on an upper surface of the first pile 1 A made of concrete, the PC steel wires 23 in the sheath tubes 24 are passed through the lid 26 and are pulled, and the first pile 1 A is caused to be tensioned and is held using the fixing tool 25. A prestress (compressive force) is also exerted on the second pile 2 A corresponding to the second steel pipe 2 through the same process.

Thus, prestress is exerted on the continuous underground wall R of the first pile 1 A and the second pile 2 A corresponding to both of the first steel pipe 1 and the second steel pipe 2 and it is possible to prevent cracks or the like by controlling a tensile stress even when the continuous underground wall R receives a load.

[0053]

It should be noted that it may not be necessary to exert a prestress on the first pile 1 A and the second pile 2 A corresponding to both of the first steel pipe 1 and the second steel pipe 2. For example, prestress may be exerted on only the first pile 1 A or only the second pile 2A. Alternatively, prestress may be introduced to only some of the first piles 1 A or some of the second piles 2 A or only concrete of a portion on which a bending load is exerted.

[0054]

In the method for constructing the continuous underground wall R according to each of the above-described embodiments, modified examples, and the like, when the second steel pipe 2 is pulled out, the first pile 1 A is unhardened at the time of excavating and disturbing the file pile 1 A made of concrete using the claws 3, 13, or 16. It is desirable that the disturbance of the first pile 1 A using the claws 3, 13, or 16 be performed in a range from a solidification start time of concrete to a solidification termination time thereof. Furthermore, the first pile 1 A may be excavated and disturbed in a state in which the first pile 1 A is in a semi-hardened state or in a hardened state even after a solidification termination time. Even in this case, the first pile 1 A can be integrated with the second pile 2A using additional replenishing concrete.

[0055]

Although the press-in machine 6 press-drives or pulls out the first steel pipe 1 and the second steel pipe 2 in the method for constructing the continuous underground wall R according to each of the above-described embodiments, modified examples, and the like, the present invention is not limited to such a constitution. A known press-in and pulling-out device can be adopted instead of the press-in machine 6.

[0056]

The claws 3, 13, or 16 in the second steel pipe 2 are formed in a circular arc plate shape but may be formed in a ring shape around the entire circumference of the second steel pipe 2. When this constitution is adopted, it is unnecessary to position the claws 3 to overlap the first pile 1 A at the time of pulling out the second steel pipe 2 and it is also unnecessary to swing or rotate the claws 3.

In this case, as in the third embodiment, it is desirable to install the second steel pipe 2 before the first steel pipe 1. Furthermore, in the method for constructing the continuous underground wall R according to each of the above-described embodiments, modified examples, and the like, the first pile 1 A or the second pile 2A may be formed by setting some of the first steel pipes 1 to be longer than the other first steel pipes 1 or second steel pipes 2.

[0057]

A modified example of the method for constructing the continuous underground wall R according to the above-described second embodiment will be described below with reference to Fig. 25.

In the constructing method according to this modified example, in Fig. 25, while first steel pipes 1 are being installed at intervals or after the first steel pipes 1 have been installed at intervals, an excavator excavates the contents in each of the first steel pipes, but the second steel pipes 2 are not sequentially installed in spaces between the first steel pipes 1. For example, each of the second steel pipes 2 may be installed between two first steel pipes 1 which are appropriately adjacent to each other. The contents in the second steel pipe 1 is excavated while the second steel pipe 2 is being installed or after the second steel pipe 2 has been installed.

Moreover, the first steel pipes 1 are sequentially pulled out while first steel pipes 1 on both sides are being filled with a solidifying material or after the first steel pipes 1 have been filled with a solidifying material. The second steel pipe 2 is pulled out while the second steel pipe 2 installed between obtained first piles 1 Aa and 1 Ab is being filled with a solidifying material or after the second steel pipe 2 has been filled with a solidifying material. At that time, the second steel pipe 2 is pulled out while the unhardened first pile 1 Aa and first pile 1 Ab are being disturbed using the claws 3 in the second steel pipe 2. Subsequently, as shown in Fig. 25, the second steel pipe 2 is installed between the first pile 1 Ab and the first steel pipe 1 and the construction may be performed as described above. Alternatively, the second steel pipe 2 may be installed between adjacent first steel pipes 1 at a distance and the construction may be performed as described above. In this way, the second steel pipes 2 need not necessarily be sequentially installed between installed first steel pipes 1 , and as a result, the constructing method may be adopted as long as a continuous wall R which is made of a first pile 1 A and a second pile 2A and is continuous is constructed.

[0058]

Fig. 26 illustrates a continuous underground wall R according to another modified example.

When continuous underground walls R are each constructed in rivers, marshes, and the like, solidifying materials such as concrete in water cannot be in a self-standing state before hardening. For this reason, a first steel pipe 1 in a first pile 1 A and a second steel pipe 2 in a second pile 2 A constituting the continuous underground wall R are not fully pulled out and a part of upper portions of the first pile 1 A and the second pile 2 A may be left in water and covered.

In the continuous underground wall R according to this modified example, the first steel pipe 1 and the second steel pipe 2 are pulled out partway from the ground in the bottom of water in a river, a marsh, or the like and first piles 1 Aa and 1 Ab and a second pile 2Aa are disturbed using claws 3 in the second steel pipe 2 and integrated. The continuous underground wall R of this portion is in contact with the ground.

In water such as rivers and marshes from the upper portion thereof, the first steel pipe 1 is left on upper portions of the first piles 1 Aa and 1 Ab and is in contact with water. Moreover, a portion of the first steel pipe 1 above the water surface may be cut off if necessary. The second steel pipe 2 is also left on the upper portion of the second pile 2Aa in the ground and is in contact with water such as a river or a marsh. The claws 3 at the lower end of the second steel pipe 2 are buried in the ground. A portion of the second steel pipe 2 above the water surface is cut if necessary. Steel pipes may be connected and extended by providing joints 28 in upper ends of the first steel pipe 1 and the second steel pipe 2 and may be separated and removed using the joints 28. When the first steel pipe 1 and the second steel pipe 2 are left in an embedment part P from the bottom of water to the upper portions of the first piles 1 Aa and 1 Ab and the second pile 2Aa in the ground, a strength of the continuous underground wall R is increased.

[0059]

A constitution in which the first steel pipe 1 or the second steel pipe 2 is left on a part of the first pile 1 A or the second pile 2 A such as the upper portion thereof in the longitudinal direction can also be applied to a case in which a continuous wall is formed in a region in which a wall protrudes above the ground such as a levee crown end in addition to an underwater portion. Thus, it is possible to join the first pile 1 A or the second pile 2A made of a solidifying material to a part of a continuous wall by bringing the first pile 1 A or the second pile 2 A into contact with a wall above the ground, for example, a continuous wall surface on which an earth pressure is exerted while being protected using the first steel pipe 1 or the second steel pipe 2. The first steel pipe 1 or the second steel pipe 2 above the ground which is continuous with the first pile 1 A or the second pile 2A is erected with a slight gap therebeween. In the present specification, such a continuous wall which extends above the ground is also assumed to be included in the continuous underground wall R.

As another modified example of the continuous underground wall R according to this embodiment, one of the arrangement of the first steel pipe 1 and the second steel pipe 2 left on the upper portions of the first pile 1 A and the second pile 2 A may be in contact with an earth wall or a solidifying material and the other thereof may be in contact with a space. Alternatively, various cases such as a case in which both of the first steel pipe 1 and the second steel pipe 2 are in contact with a space, a case in which one of the first steel pipe 1 and the second steel pipe 2 is in contact with a soil wall or a solidifying material and the other thereof is in contact with the water surface, and the like can be provided.

Industrial Applicability

[0060]

According to the present invention, it is possible to form the continuous underground wall in which the pile bodies are joined by pulling out the second steel pipe while the pile bodies are disturbed using the claws in the second steel pipe between the piles made of the solidifying material in which the first steel pipe is pulled out. For this reason, it is possible to reliably construct the continuous underground wall in which the pile bodies made of the solidifying material are integrated with a small number of steps.

Moreover, it is possible to prevent collapse of the solidifying material at the time of constructing, to prevent the production of industrial waste and to reduce the number of parts and the number of working operations because bentonite or the like is not used. [Reference Signs List]

[0061]

1 First steel pipe

1A, lAa, lAb, lAc First pile

2 Second steel pipe 2A, 2Aa, 2Ab Second pile 3, 16 Claw

6 Press-in machine

21 Prestress unit

23 PC steel wire

24 Sheath tube

R Continuous underground wall