Description

Field of invention field

The invention relates to locking structures used for connection of piles rammed into the ground, more specifically it relates to a concrete pile connector that is locked by means of energy applied to the piles when rammed or vibrated into the ground.

Background

Piles are an important part in many construction works, from foundation of buildings to roads, railways and port facilities. In northern areas with frost heave and permafrost piling are particularly useful. Globally thousands of kilometers of piles are piled each year.

Piling is done executed by a rig comprising a pile tower and a weight from few hundred kilos to several thousand kilos which rams the pile into the ground. The piling rig may also employ a powerful vibrator having substantially the same effect as a ramming w eight. For the pile tower not be too high and impractical and to enable transfer of the piles, the piles must be connected w hen there is need for longer lengths. For this purpose a pile connector is needed.

EP 2186944 discloses a locking structure for extension of reinforced concrete piles. The first reinforced concrete pile and the second reinforced concrete pile has, at its

interconnecting ends, a lock housing which is provided with transverse holes, and lock pins w hich are provided w ith transverse holes. The lock housing and the lock pin extends into each other with said transverse holes aligned. Said locking structure includes a locking ring on each inner extension of the transverse hole in the lock housings. Said locking ring has between its outer diameter and its inner diameter a continuous circumferential segment, and between the inner diameter and a bore diameter of a central opening, spring blades are separated from one another by radial slots. Said locking structure also comprises insert pins, an inner end w ith cylindrical or polygonal cross section, which has an engagement diameter smaller than the inner diameter of the locking ring and larger than the inner diameter of the locking ring.

This solution requires that the insert pins is inserted manually and rammed in w ith the sledgehammer while pile tower holds the unsecured pile. It is also known that it can be welded or bolted. Common for these solutions is that the work must be done manually over a period of time near heavy machinery and unmounted piles. This is not satisfactory in terms of health and safety (EHS), and also takes time.

Intention of the invention

The object of the present invention is to provide a pile connector which locks the piles together by the weight of the pile to be connected and the energy used to ram the piles into the ground. This means that an operator need only to put a fastening device comprising tw wedge elements and an expansion member into each lock in the pile armature which are rammed into the ground before the other pile is lifted into position, thus avoiding working at the load. Furthermore, this means that the time where expensive machinery must wait for an operator to perform welding, tapping with sledgehammer or other operations, is saved. summary of the invention

The invention relates to a pile connector for coupling two concrete piles driven into the ground by ramming or vibration comprising: two pile armatures cast into the end of the piles to be connected, each pile armature comprises at least one lock space, wherein the entrance to the lock room has a smaller radius than the lock space, wherein the locking spaces of the two pile amiatures are pairwisc against each other and wherein each pair of lock spaces have a corresponding fastening unit comprising: one expansion element which fits into the inner diameter of the lock space and two wedge elements having a neck portion that fits into the inside of the tubular expansion element, and having a head portion which fits into the respective lock space.

Furthermore the invention relates to a method for connecting two piles using a pile connector according to this invention, comprising the steps of: setting the fastener (s) into the locking space (s) in the concrete pile that is to be rammed into the ground: guide the lock space (s) of the pile to be connected dow n onto the upper ends of the fixing device (s); and locking the pile connector by tapping or vibrating the concrete pile into the ground.

Brief Description of the Figures

For a better understanding of the invention, and to show how embodiments of the invention may be used, reference will now be made, by way of example, to the accompanying diagrammatic draw ings in hich:

Figure 1 shows a pile armature from the side facing out from the pile surface.

Figure (2) a shows two wedges and an expansion element which is not activated. Figure (2) b shows two wedges and an expansion element which is activated.

Figure (3) a shows a pile connector before activation.

Figure (3) b shows a pile connector after activation.

Detailed Description of the Invention

Figure 1 shows an embodiment of a pile armature ( 1 ) where it is displayed four lock spaces (2) and four reinforcement rods (3) for casting the pile armature into the pile. Preferably, the reinforcement attached to the locking feature. Typical dimensions of a concrete pile varie from 20 x 20 cm to 60 x 60 cm. but they can also have other dimensions and may be round or rectangular.

The pile armature ( 1 ) may include one or more lock spaces (2). The lock space (2) may be made of a sturdy metal e.g. steel and go deep enough into the end face of the pile so that the piles are locked together. The further the lock chamber (2) projects into the pile and the w ider it is. the greater the friction surface / locking surface becomes and the more strongly the piles are locked to each other. This correlation applies until the lock spaces (2) are so wide that the strength is weakened because they extend too close to the side edges of the pile. In a simplified embodiment it is possible that the pile armature ( 1 ) only is a plate embedded in the pile surface by means of reinforcing bars (3 ) and that the lock space (2) is only a cavity in the concrete.

Furthermore the pile armature ( 1 ) may comprises a section (4) perpendicular to the pile surface that completely encloses the end of the concrete pile at a distance from the concrete pile end at least equal to the depth of the lock space (s) (2) to counteract the expansion forces from the expansion member (s) (5) and provide support to the concrete.

Figure 2A shows two pairs of wedge elements (6) and an expansion element (5 ) designed as a hollo lube before it is rammed into a locking position as show n in Figure 2B. In this embodiment this constitutes a fastening unit (20) which is inserted into the lock space (s) of the lower pile before the next pile is placed on top of this. In this

embodiment, one wedge element is slightly longer than the other so that the expansion element (5 ) is filled ith a metal core w here the expansion element (5) passes from the first armature ( 1 ) to the second armature ( 1 )

In some embodiments, the expansion element is provided w ith a central portion (7) in w hich the expansion element (5 ) is not a pipe, but is made of compact metal. In this way. deformation in the area between the two piles in the expansion element (5 ) is

counteracted. This deformation may lead to a bad lock or perhaps a skewed lock, if any of the metal from the expansion element (5) comes between the two pile armatures ( 1 ). In a further embodiment, the expansion element 5 is made of a non-expandable middle section (7). for example in the form of a harder metal or the like to ensure that the middle portion does not enter into the area between the two pile armatures 1 and prevent them from contacting each other.

The w edge element (6) may have many forms, one of which is shown in Figure 2Λ and B. The wedge element 6 here comprises a neck portion (8) w hich fits into the form of the expansion element (5) and a wider head portion 9 wherein the transition between the neck portion (8) and the head portion (9) exhibits an inclined surface ( 1 1 ) for causing the expansion element to expand when the pile is rammed or vibrated into the ground by a piling rig. because the head 9 of the wedge elements abuts against the bottom of the upper and lower lock space (2). Thus, the whole weight of the pile to be connected and the energy from the ramming or vibrating mechanism of the piling rig to go through all of the expansion elements (5) that exists in the connector and deform them into a locked position. Thus, much of the process of connecting the piles to each other will take place while ramming or vibrating is in progress, not before ramming or vibration starts, as is the case in the prior art. and thus time will be saved.

The bottom of the lock space (2) can be narrowed to receive and closely surround the head (9) of the wedge element (6) and thus provide additional support.

Advantageously the head (9) of the wedge element (6) has a conical portion facing upward when the fastening unit (20) is inserted into the lock space (s) (2) to the lower pile to facilitate guiding the pile to be connected in the correct position.

In order to counteract the stretching forces acting on the pile connector 10. which is a result of the lower pile bouncing off the upper pile when the upper pile is rammed, a resilient seal or gasket may be provided between the two pile armatures 1 in a pile connector 1 .

Advantageously the two pile armatures ( 1 ) on the end faces of the piles to be connected are symmetrical about a plane extending perpendicular to the piles longitudinal axis and midway between the two armatures ( 1 ) on the piles to be connected together. This reduces the possibility of errors in the process: The piles cannot be lifted in the wrong end and fastening devices (20) cannot be inserted the wrong way. The length of the two wedge elements (6) and. if present, the compact central portion (7) of the expansion element (5). should not be longer than the depth of the two opposite lock spaces (2). but should be approximately the same length, in order to reduce the play. Furthermore, the volume of material in the upper and lower halves of the expansion element (5) should not be greater than the volume between the respective wedges and lock space. It is also conceivable that a wedge element (6) is integrated or permanently mounted to the bottom of the lock space (2).

In another embodiment, the expansion element 5 is made of a resilient metal and divided into at least two parts in both ends that go into the locking space (2), so that the wedge element (6) can be pressed between these parts and expand the ends of the expansion element (5) to a radius greater than the entrance radius of the lock space (2). thereby locking the ends permanently in the locking space (2).

Figure 3A shows the fastening unit of the pile connector ( 10) before it is rammed to a locked position as shown in Figure 3B. The lock space in this embodiment has an extended section ( 12) which can accommodate the expanded expansion element after it is expanded over the inclined surface ( 1 1 ). Ideally, the expansion element should meet sufficient resistance between the recess and lock room so that the part of the extended section ( 12) nearest the pile end is filled with metal the greatest possible extent and thereby provides a restraint w ithout play. This can be adjusted by the metal formability and angle of the inclined surface ( 1 1 ) of the wedge element. The angle between the inclined surface ( 1 1 ) of the wedge element 6 and the longitudinal axis of the wedge element 6 should be between 0 and 45 degrees, more preferably between 15 and 35 degrees.

Typical dimensions for the head (9) of the wedge element (6) will be the same radius or slightly smaller than the entrance to the lock chamber (2). The cylindrical part of the wedge element (6) will be the same radius as the inner radius of the expansion element (5). The two wedges must be readily inserted into the two ends of the expansion element and together form a fastening unit 20 that can be inserted into the lock space (s) 2. The space between the various units should be between 0 and I mm. but can also be more. The thickness of the walls of a tubular expansion clement (5) will be approximately 1 - 1 /4 of the neck (8) radius and equal to the difference between the radius of the neck portion (8) and the maximum radius of the head. Radius to lock the room will typically be equal to the radius of the head (9) plus the thickness of the expansion element and a little extra. Radius or size o a lock space will depend on the number of lock spaces. With 4 lock spaces (2) in a 275 x 275 mm piling the radius of the entrance of the lock space will typically be approximately 10-20 mm. more preferred approximately 15 mm.

It should be noted that the above described embodiments are examples only and arc not intended to limit the invention, e.g. the skilled person who is familiar with the art can change the shape and number of w edges (6), the expansion elements (5) and lock spaces (2). and the choice of material without departing from the scope of the invention defined by the claims.