TECHNICAL FIELD OF THE INVENTION

The present invention relates to civil engineering, in particular, a pile installation system and method.

BACKGROUND OF THE INVENTION

Pile installation in a construction project often leads to noise and ground vibration-related issues or problems. Although there are a few pile installation techniques available to the operator, certain techniques can be ill-suited to certain construction sites. For example, a particular pile installation technique can be ill-suited to an urban environment where noise and ground vibration legal limit are stringently regulated in order to reduce noise pollution to surrounding residents and/or structural damages to nearby properties. Accordingly, a pile installation system which can reduce noise and ground vibration is desirable.

Patent Publication No. CN 110374090 disclosed a soft foundation concrete filling pile construction device. The device comprises a supporting framework use for being placed in a pile hole, multiple reinforcing steel bars circumferentially and evenly fixed to the supporting framework in a crossing manner, an operating platform use for fixing the supporting framework and crossing of the reinforcing steel bars a lifting mechanism use for lifting and reducing the operation platform. The position precision and the mounting construction efficiency of the cast-in-situ bored piles can be improved.

Patent Publication No. CN110144885 disclosed a three-section large-diameter bored pile structure suitable for foundation construction of an ultra-large sea-spanning bridge. The three-section large-diameter bored pile structure consists of a concrete pile body, inner side main reinforcements, outer side main reinforcements, stirrups, perforated H-shaped steel cylindrical supports, triangular angle steel cylindrical supports and acoustic pipes. The three-section large diameter bored pile structure comprises three sections from top to bottom structurally, and different structural styles are employed by the three sections. The upper section and the lower section of the pile structure are each of a double-layer main reinforcement structure, and the middle section of the pile structure is of a single-layer main reinforcement structure. The inner side main reinforcements of the three-sections of structures are connected vertically to form an integral reinforcement cage. The integral reinforcement cage is put into a vertical deep hole formed by employing a hole drilling method and integral concreting is performed to form an integral pile foundation structure.

Patent Publication No. CN208996025 disclosed a double-pile-casing pile foundation construction structure for a deep silt layer wherein the outer pile casing penetrates through silt and silty clay layer during pile foundation hole forming and is pulled out after concrete pouring. A retaining wall water-retaining head-bore forming structure is arranged on the outer wall of the outer pile casing. An inner pile casing is arranged in an inner cavity of the outer pile casing and cannot be pulled out. A plugging material is arranged between the lower end of the inner pile casing and the lower end of the outer pile casing. A pile foundation reinforcement cage is arranged in the inner cavity of the inner pile casing and the concrete is poured into the inner cavity of the inner pile casing.

Patent Publication No. CN204059390 disclosed a double casing bored pile for highly corrosive salty soil and a construction method of the double-casing bored pile. The double-casing bored pile for the highly corrosive salty soil comprises an outer casing and an inner casing. The inner casing is positioned in the outer casing and made of precast concrete and a steel reinforcement framework is arranged in the precast concrete. The steel reinforcement concrete inner casing can be precast on a precast component factory in batch or on-site. The construction requirements on the quality of the casing concrete, the thickness of a protective layer and the like can be sufficiently guaranteed. The inner casing is conveniently assembled and taken place on-site, and excessive trouble in construction is avoided.

None of the prior art teaches or suggest a bored pile system which reduces noise pollution to surrounding residents and/or reduces vibration to avoid structural damages to nearby properties. Accordingly, an alternative pile installation system which can reduce noise and ground vibration is desirable.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a pile installation system and method which reduces noise pollution to surrounding residents and/or reduce vibration to avoid structural damages to nearby properties.

In a first aspect of the invention, the invention provides a pile installation system. In an embodiment of the invention, the system comprises an operating platform and a plurality of casings of varying lengths and diameters. The operating platform is configured to enable functions relating to pre-boring for the introduction of the casings into the ground, lifting the casings into position, driving the casings into the ground, drilling and displacing of soil and materials within the casings, and extracting the casings from the ground after the borehole has been cast with concrete or once the pile has been formed. Each of the plurality of casings is arranged inside one another so as to avoid collapsing of the borehole as well as reducing shock and vibration while drilling to form a borehole for the construction of a bored pile is ongoing and thus reducing the noise disturbance and well as the risk of causing damages to nearby buildings or structures.

In an exemplary embodiment of the invention, the invention comprises an operating platform and a plurality of casings. Said plurality of casings includes two casings including an inner casing and an outer casing. The outer casing is shorter than the inner casing. The inner casing and the outer casing are of varying length and diameters such that it enables the inner casing to be arranged inside the outer casing. The outer casing holds the soft soil preventing it from collapsing as well as alleviates shock and vibration while drilling inside the inner casing is ongoing to form a borehole for in-situ bored pile construction.

In a further exemplary embodiment of the invention, the plurality of casings includes three casings including an inner casing, an outer casing and an optional-outer casing. The three casings are of varying lengths and varying diameters such that it enables the outer casing to be arranged inside the optional-outer casing and the inner casing arranged inside the outer casing, respectively. The optional-outer casing and the outer casing hold the soft soil preventing it from collapsing as well as alleviate shock and vibration while drilling inside the inner casing is ongoing to form a borehole for in- situ bored pile construction.

In a second aspect of the invention, the invention provides a piling installation method using the piling installation system of the first aspect.

BRIEF DESCRIPTION OF DRAWINGS

Characteristics and advantages of the invention will be appreciated from the following description of exemplary embodiments of the present invention, in which, as a non-limiting example, some preferable embodiments of the principle of the invention are described, with reference to the accompanying drawings of FIGs. 1-8 in which;

FIG.l shows an embodiment of a pile installation system according to the present invention;

FIG. 2 shows an exemplary example of a service crane for use in a pile installation system and method according to the present invention;

FIG. 3 shows an exemplary example of an arrangement of casings with a detail illustration of arrangement between the casings and a casing holder/ a casing driving means;

FIG. 4 shows an exploded view of an arrangement of the casings with the casing holder/casing driving means of Fig. 3;

FIG. 5.1 shows a further illustration of an arrangement of the casings according to an embodiment of the invention;

FIG. 5.2 shows a sectional view of the arrangement of the casings of FIG. 5.1; FIG. 6.1 shows an illustration of an arrangement of the casings according to an embodiment of the invention;

FIG. 6.2 shows a sectional view of the arrangement of the casings of FIG. 6.1 ;

FIG. 7 shows an illustration of an arrangement of the casings according to an embodiment of the invention with a counterweight; and

FIG. 8 shows a comparative vibration test results between a conventional method (vibro hammer) and the present invention.

DETAIL DESCRIPTION OF THE INVENTION

The present invention provides a pile installation system and a method for piling installation. For the purposes of understanding of the principle of the invention, characteristics and advantages of the invention will be described as non-limiting examples of some preferable embodiments of the principle of the invention with reference to the accompanying drawings as shown in FIGs 1-8, in which:

In a first aspect of the invention, the invention provides a bored pile installation system. In an embodiment of the invention, the pile installation system comprises an operating platform and a plurality of pile casings. Said plurality of pile casings, two casings or more are included, is of varying length and diameter. Each of the plurality of casings is arranged inside one another in sequential according to its diameter. Preferably the casing which with a shorter length has a larger diameter such that it allows the casing which with a greater length and smaller diameter to be positioned inside. A borehole for construction of a bored pile is formed inside the casing with a smaller diameter (if two pile casings are used) or the pile casing with the smallest diameter (if more than two casings are utilized) in the construction of a bored pile. The operating platform is configured to carry out functions relating to pre-boring for the installation of the casings into the ground, lifting the casings into position, driving the casings into the ground, drilling and displacing of soil and materials within the casings, and extraction of the casings from the ground after the borehole has been cast with concrete or once the bored pile has been cast or formed. The plurality of casings is arranged to avoid the collapse of the borehole as well as to reduce shock and vibration while drilling is ongoing and thus reducing the noise disturbance and well as the chance of causing damages to nearby buildings or structures.

FIG.l shows an embodiment of the pile installation system 100 which involves an operating platform 105 and a plurality of casings 200. In an embodiment, said plurality of casings 200 includes an inner casing 110 and an outer casing 115. In an exemplary embodiment, as also shown in FIGs. 3 to 5.2, the outer casingl l5 has a larger diameter than the inner casing 110 such that it allows the inner casing 110 to be positioned inside the outer casing 115. In a preferred embodiment, the diameter of the inner casingl 10 is equal to D whereas the diameter of the outer casing is equal to D+ 0.15 meter. For example, if the diameter of the inner casingl 10 is 1 meter, the diameter of the outer casing 115 shall be 1.15 meters. Further, the outer casing 115 is shorter in length than that of the inner casing 110. The length of the outer casing 115 should correspond with the depth of the topsoil or soft soil layer at the construction site such that once the outer casing 115 is driven into the ground it holds the soft soil from collapsing as drilling inside the outer casing 115 is ongoing to accommodate the inner casing 110. Similarly, the inner casing 110 which is positioned inside the outer casing 115 and is longer than the outer casing 115 to hold the deeper layer of the soil such as the clay soil from collapsing as drilling within the inner casing 110 is progressing to form a borehole with a predetermined depth for an in-situ bored pile construction. The arrangement of the inner casing 110 and the outer casing 115 in combination with rotary drilling inside the inner casing 110 reduces noise and vibration disturbances to surrounding areas.

In more detail, the operating platform 105 comprises a rotary boring machine 125 and a service crane 130. An exemplary example of a service crane 130 that may be used is shown in FIG. 2. The rotary boring machine 125 is configured to carry out a pre-boring at a designated location where a bored pile is to be constructed according to the construction plan. The pre-boring by the rotary boring machine 125 enables positioning of the outer casingl 15 to be driven into the ground, in particular into the soft soil layer. In an example, the rotary boring machine 125 pre-bored the topsoil to a depth of about 3-4 meters such that it can initially accommodate the outer casing 115 therein. The rotary boring machine 125 is equipped with a casing holder 135 configured to secure to the casings 200 in order to lift and position the casings 200 including the outer casing 115 into the hole pre-bored by the rotary boring machine 125. The outer casing 115 is driven into the ground using an appropriate casing driving means such as a counterweight 145 or a casing rotator 150 or a combination of both as the case may be. In an example, on certain construction site, the outer casing 115 may be driven into the soft soil layer simply via a counterweight 145 assembled to the service crane 130. In another example on other construction sites, the outer casing 115 may be driven into the soft soil layer with the casing rotator 150 assembled to the rotary boring machine 125. In a further example, in a further construction site, the outer casing 115 may be driven into the soil layer using a combination of both the counterweight 145 and the casing rotator 150. The rotary boring machine 125, i.e. the casing rotator 150 is equipped with the casing holder 135 configured to secure to an end of the casings 200 so as to rotatably drive the casings 200 into the soil layer. Once the outer casing 115 is positioned and driven into the ground reaching a predetermined depth, the soft soil within the outer casing 115 is removed by the rotary boring machine 125. Drilling and removing of soft soil within the outer casing 115 may continue as long as the hole within the outer casing 115 remains stable, for example to a depth of about 8-10 meters. Obviously, the depth may be adjusted according to the soil characteristics at the construction site. Drilling and removing of the soft soil within the outer casing 115 allow positioning of the inner casing 110 into the outer casing 115. The inner casing 110 can be then driven into the deeper soil layers to reach a predetermined depth using the counterweigh 145 or the casing rotator 150 or a combination of both in a similar manner as with driving of the outer casing 115. The inner casing 110 may be initially driven into the soil using the counterweight 145. Once the inner casing 110 is driven beyond the soft soil reaching a harder soil layer and it is no longer efficient to use the counterweight 145 as the casing driving means, the inner casing 115 may be further driven into the soil using the casing rotator 150 to improve efficiency as well as to minimize the noise and vibration. Further, as mentioned earlier, the inner casing 110 is longer than the outer casing 115. Preferably, the inner casing 110 should be with sufficient length to correspond a combined depth of the soft soil layer and the clay layer so as to protect the hole from collapsing due to displacement of these soil layers as drilling is progressing to the final depth. In an example, the inner casing has a length of about 12-14 meters. In certain soil condition, for example, in a construction site with a very deep layer of soft soil including the clay soil layer, it may be necessary to further drive the inner casing 110 in alternate with extracting the soil including other materials from the inner casing before reaching the desired depth of the borehole. In certain soil condition, such as in unstable soil strata, it may be necessary to use stabilizing fluid to stabilize the borehole.

Once the inner casing 110 is driven to reach the desired depth and the soil including other materials are extracted out of the inner casing 110 using a rotary drill and/or a bucket (not shown) or a combination thereof. Since drilling and extracting of soil occurs within the inner casing 110 and the fact that the inner casing 110 is placed within the outer casing 115 with a gap of, for example, about 0.15 meter, it effectively reduces vibration while drilling and extracting is in progress. Also, since the casings 200 are driven into the ground through the use of predominantly the casing rotator 150 assembled to the rotary boring machine 125 it effectively reduces the noise disturbance in comparison to the vibrating method in a conventional bored piling method.

Once the soil, as well as other materials, are sufficiently extracted out of the inner casing 110 the concrete may be then poured into the borehole prepared within the inner casing 110, for example through a tremie pipe (not shown). Preferably, a reinforcement structure such as a reinforcement steel structure (not shown) is placed within the said borehole prior to pouring of concrete into the borehole. Once the borehole is completely filled with concrete, the inner casing 110 and the outer casing 115 are respectively extracted out of the ground. For example, the inner casing 110 is first extracted out of the ground followed by the extraction of the outer casing 115. The extraction of the inner casing 110 and the outer casing 115 may be performed with the aid of the rotary boring machine 125 or the service crane 130 or a combination of both. For example, the inner casing 110 may be extracted first and followed by the extraction of the outer casing 115. The extraction of the inner casing 110 and the outer casing 115 can be performed simply by pulling the casings 200 up, preferably without shaking or rocking the casings 200. In the event of a strong pulling force by the surrounding soil to the casings 200, in particular, the inner casing 110 which is deep in the ground, the inner casing 110 may be extracted with the aid of the rotary boring machine 125 by securing the inner casing 110 to the casing holder 135 and rotate the inner casing 110, for example, half turn left to right in alternate while pulling at the same time.

FIGs. 6.1-6.2 show another example of the pile installation system 100 according to the present invention. In this embodiment, the invention pile installation system 100 further comprises an optional-outer casing 120. That is, the pile installation system 100 comprises the operating platform 105 and an inner casing 110, an outer casing 115 and an optional-outer casing 120.

In the same principle as with the earlier described embodiment, the inner casing 110, the outer casing 115 and the optional-outer casing 120 are of varying length and diameter. That is, the inner casing 110, the outer casing 115 and the optional-outer casing 120 are of a varying diameter such that it permits the outer casing 115 to be positioned inside the optional-outer casing 120 and the outer casing 115 permits the inner casing 110 to be positioned inside the outer casing 115. In other words, the plurality of casings 200 is arranged inside one another in the ground in sequential order according to its diameter starting from the casing with the largest diameter which permits arrangement of the next and subsequent casing with the next smaller diameter in sequential order.

In this exemplary embodiment as shown in FIGs. 6.1 to 6.2, multiple casings such as three casings are particularly useful for construction near waterways such as a river or construction on the flooded area where there is a high risk of collapsing of a borehole. In this example, the inner casing 110 has a length of about 12-14 meters and a diameter of D meter (expression of measurement of the diameter is in meter unit). The outer casing 115 has a length of about 4-6 meters and a diameter of D+0.15 meter. The optional -outer casing 120 has a length of about 2-4 meters and a diameter of D+0.45 meter. The optional-outer casing 120 is positioned and is driven into the topsoil layer. The outer casing 115 is then positioned inside the optional-outer casing 120 and is driven into the soil layer, the inner casing 110 is then positioned inside the outer casing 115 and a borehole is formed inside the inner casing 110 for the construction of bored pile therein. The installation of the optional-outer casing 120, the outer casing 115 and the inner casing 110 is the same as that of the same principle as described in the earlier embodiment, i.e. using the service crane 130 or the rotary boring machine 125 or a combination of both as the case may be. Thus, specific detail thereof will not be repeated here. As well, the extraction of the soil or any other materials within the inner casing 110 including the outer casing 115 and the optional-outer casing 120, if necessary, also use the same method as in the earlier described embodiment.

The characteristics of the plurality of casings 200 including the inner casing 110, the outer casing 115 and the optional-outer casing 120 and their arrangement as well as the relationship between each of them restrict collapsing or displacement of soil and reduce ground vibration while forming a borehole is in progress. That is, the inner casing 110, the outer casing 115 and the optional-outer casing 120 not only prevent collapsing of the soil surrounding the borehole, they also restrict shock and vibration, resulting from drilling and extracting of soil and materials while forming the borehole, from travelling through the soil layer thereby lowering the risk of damages caused by strong vibration to buildings or structures nearby the construction site.

In another aspect of the invention, the invention provides a bored pile installation method utilizing the bored pile installation system 100 previously described in the first aspect of the invention. In an embodiment of the invention, the method comprising the steps of the followings:

-providing an operating platform 105 comprising a rotary boring machine 125 and a service crane 130;

-providing a plurality of casings 200 of varying lengths and diameters;

-positioning and driving the plurality of casings 200 in sequential order according to its diameter such that the plurality of casings 200 is arranged inside one another starting from a casing with a large diameter to a casing with a small diameter, with the aid of the operating platform 105, into the ground to a designated depth at a location where a bored pile is determined;

-drilling and excavating soil and materials inside the casing having the smallest diameter to form a borehole;

-casting a bored pile into said borehole; and

-extracting the said plurality of casings 200 out of the ground.

In which;

In the step of providing the operating platform 105, the operating platform 105 comprises the rotary boring machine 125 and the service crane 130 configured to carry out functions relating to pre-boring, positioning and driving the casings 200 into the ground, drilling and excavating of soil and materials within the casings 200, and extracting the casings 200 from the ground after the borehole has been cast with concrete or once the bored pile has been cast or formed.

Further, in the step of providing a plurality of casings 200, said plurality of casings 200 includes for example an inner casing 110 and an outer casing 115, or in another example, an inner casing 110, an outer casing 115 and an optional-outer casing 120. The plurality of casings 200 has varying lengths and diameters wherein the casing which with a shorter length and a larger diameter allows the next and subsequent pile casing which with a greater length and smaller diameter to be positioned inside. In other words, the plurality of casings 200 is arranged sequentially inside one another according to their diameter. For example, the inner casing 110 with a diameter of D meter is arranged inside the outer casing 115 with a diameter of D+0.15 meter. In another example, the optional-outer casing 120 with a diameter of D+0.45 meter is arranged in position first and subsequently the outer casing 115 with a diameter of D+0.15 is arranged inside the optional-outer casing 120 and then the inner casing 110 with a diameter of D meter is arranged inside the outer casing 115. Further characteristics of each casing and its arrangement and relationship to one another are as discussed in the earlier described aspect of the invention and thus specific detail will not be repeated. In the step of positioning and driving said plurality of pile casings 200 into the ground at a location where a bored pile is designated, positioning and driving of each of the casings including, the inner casing 110, the outer casing 115 and the optional- outer casing 120 are carried out with the aid of the rotary boring machine 125 or the service crane 130 or a combination thereof as the case may be. Among said plurality of casings 200, each of the casing is arranged inside one another in sequential order according to their diameter, starting from the largest to the smallest. Pre-boring with the rotary boring machine 125 to facilitate positioning said casings 200 before being driven into the ground may be carried out, if necessary. For example, once the optional- outer casing 120 is positioned and driven into the ground, boring within the optional- outer casing 120 may be carried out before positioning the outer casing 115 into the optional-outer casing 120. Similarly, once the outer casing 115 is positioned and driven into the ground, drilling and boring within the outer casing 115 may be carried out prior to positioning the inner casing 110 into the outer casing 115. in the step of drilling and excavating of soil and materials from inside the casings 200, following the arrangement of the plurality of casings 200 in the ground, the soil and materials from inside the casing with the smallest diameter which a bored pile is to be formed i.e. the inner casing 110 is removed by drilling using a rotary drill (not shown) and a bucket (not shown) or other method or apparatus known in the art. Application of stabilizing agent to stabilize the borehole while drilling and excavating of soil and materials may be carried out while drilling and excavating is in progress.

In the step of casting a bored pile into a borehole, in this step, in-situ casing to form a bored pile is carried out by filling the borehole with concrete. Reinforcement structure may be positioned inside the borehole prior to filling the borehole with concrete

In the step of extracting the plurality of casings 200 from the ground, once the casting is complete, the plurality of casings 200 is extracted from the ground. Extracting of the plurality of casings 200 is generally started from the casing with the largest diameter. For example, in the exemplary embodiment with two casings, the outer casing 115 is extracted first followed by the extraction of the inner casing 110. In the exemplary embodiment with three casings, the optional-outer casing 120 is extracted first followed by the extraction of the outer casing 115 and the inner casing 110, respectively. The extraction of the plurality of casings 200 is once again carried out with the aid of the rotary boring machine 125 or the service crane 130 or a combination thereof if necessary. Extraction of casings 200 starts first with the extraction of the inner casing 110 and followed by the outer casing 115. The extraction of the inner casing 110 and the outer casing 115 may be carried out simply by pulling the casings up, preferably without shaking or rocking the casings. However, in some case, where the cut-off level of concrete is deeper than the tip of the outer casing 115, the inner casing 110 shall be extracted first. The outer casing 115 shall be pulled out after the concrete of the bored pile has set. In the event of a strong pulling force by the surrounding soil to the casings, in particular, the inner casing 110 which is deep in the ground, the inner casing 110 may be extracted with the aid of the rotary boring machine 125 by securing the inner casing 110 to the holder 135 and rotate the inner casing 110, for example, half turn left to right in alternate while pulling at the same time.

It is obvious to a skilled person in the art that principle relating to pile verticality and deviation checking shall be observed and practised throughout all the step of the bored pile installation.

EXAMPLE

The following are comparative vibration test results between the conventional method (vibro hammer) and the present invention with a plurality of casings.

Comparative vibration tests were conducted and vibration reading between a conventional vibro hammer method for installation of bored pile and the present invention. The readings obtained from the two methods were compared and set against a legal limit prescribed for each type of buildings including preserved buildings, residential buildings and office buildings. The vibration readings were recorded at a distance of 7.5, 15.0 and 22.5 meters from a location where casing installation is taking place. As shown in FIG. 8, the test results show that the conventional vibro hammer method generates much higher vibration. At a distance of under 10 meters from the borehole, the vibration generates by the conventional method exceeds the prescribed legal limit for preserved buildings and residential buildings and is within the legal limit for office building only. At a distance of 15 meters from the borehole, the vibration generates by the conventional vibro hammer method still exceeds the prescribed legal limit for preserved buildings and is with the legal limit for residential building and office buildings. Only when at the distance of more than 20 meters that vibration generates by the conventional method are within the prescribed legal limit for all types of buildings. In contrast, the bored pile installation method according to the present invention generates vibration recorded at distances of 10 meters (at 7.5meters), 15 meters and more than 20 meters all of which are within the prescribed legal limit for all type of buildings. This confirms that the present invention generates far less vibration in comparison to the convention method making it suitable for construction projects in urban areas where bored pile construction in close vicinity to surrounding buildings and structures is less likely to cause structural damages to nearby buildings and structures caused by strong vibration.

It will be appreciated that on the basis of the foregoing principle, description and examples, the characteristics, and the arrangement and the relationship between each of them restrict collapsing or displacement of soil, generates lower noise disturbance and reduce ground vibration while forming a borehole in preparation for the casting of a bored pile is in progress. Thus, the objectives of the invention as set out above thus have been met.

It should be appreciated by a skilled person that the foregoing description, exemplary embodiments and examples as well as the accompanying figures illustrate the principles, preferred embodiments and modes of operation of the invention. However, the invention should not be construed as being limited to the particular embodiments and examples discussed above. Accordingly, it should be appreciated that variations to those embodiments can be made without departing from the scope of the invention.