JPH0458846B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a wall-shaped friction pile suitable for a foundation when constructing a civil engineering/building structure on soft ground such as a clayey soil layer or a peat layer. In more detail, a planar bag-like body in which a large number of locally bound parts are dispersed is placed in the ground, and a filling material such as mortar is press-fitted into the bag-like body, and the unbound parts are This relates to a method for driving wall-shaped friction piles that bulge out so as to press into the surrounding ground to obtain a large bearing capacity.

[Prior Art] Pile foundations are extremely commonly used as foundations for constructing civil engineering and architectural structures.

Piles can be broadly classified into tip support piles and friction piles. Tip-supported piles are piles whose tips reach layers with sufficient bearing capacity, such as bedrock or hard gravel layers, and most of the load supported by the pile is transferred from the pile tips to these layers. Friction piles, on the other hand, are driven into sand, silt, or cohesive soil layers, and their tips do not reach the supporting layer, and the load is transmitted into the ground due to the friction between the pile and the surrounding soil. These piles have a simple cylindrical shape.

[Problems to be Solved by the Invention] Driving tip support piles is the most reliable method, but if the support layer is deep, problems such as technical difficulty and economical burden may occur. For this reason, friction piles are often used.

However, in cases where the ground is soft and the frictional force is small, such as in a layer of cohesive soil or peat, cylindrical friction piles may have a small pile bearing capacity, making it impossible to construct a pile foundation.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, and to provide a wall-shaped friction pile that can obtain a large supporting force even in soft ground where it is difficult to obtain a friction force using the conventional technique, and that can be easily constructed. The object of the present invention is to provide a pouring method.

[Means for solving the problem] The frictional force between the ground and the piles is determined not only by the characteristics of the ground, but also by the combination of the ground and the piles.
Therefore, even in extremely soft ground such as a peat layer, where sufficient frictional force could not be obtained using conventional techniques, it is possible to increase the frictional force by changing the shape and structure of the pile. However, a pile that exerts a large amount of frictional force naturally requires a large amount of force to be driven into the pile. Forcibly driving a pile may disturb the surrounding soil and cause a loss of frictional bearing capacity, and driving the pile itself may become impossible.

The present invention is a method devised to avoid such unreasonableness, facilitate pouring, and obtain a large supporting force. That is, the present invention provides a planar bag-like body with
A large number of binding parts for locally binding both sides of the bag are distributed, and the bag-like body is placed in the ground, and a filler is press-fitted into the bag-like body, and the unbound part is expanded. Let it come out and push into the surrounding ground,
This is a method of driving wall-shaped friction piles that are left to harden.

Here, "locally bound" refers to a state in which that part cannot bulge freely unlike other parts, in other words, a state in which the bulge can be restrained to some extent.

As a method for positioning a planar bag-like body in the ground, there is a method of forming a slot of a predetermined shape in the ground in advance and inserting the bag-like body into the groove. Alternatively, a method may be adopted in which the bag-like body is held along a plate-shaped pushing member, pushed in as it is, and only the pushing member is pulled out, without forming a slot in the ground in advance.

[Function] When a filling material such as mortar is press-fitted into the inside of a planar bag-like body located in the ground, the unbound part of the bag-like body bulges out, deforms so as to press into the surrounding ground, and then hardens. A wall-like friction pile is formed underground.

It is relatively easy to insert the planar bag-like body into the ground, and since the bag-like body then expands and pushes into the ground, the ground is rarely disturbed.
The expansion and deformation of the pile consolidates the ground near the pile.
The ground strength in that area increases, the adhesion between the pile surface and the soil in contact becomes stronger, and the contact area also increases, resulting in a large frictional bearing capacity.

The piles driven by the present invention have a wall-like shape that bulges out locally, and because they are dispersed, in addition to the above-mentioned consolidation effect, the bulge part is supported from below. In addition, the supporting force of the piles is further increased, and the piles are suitable for superstructures.

Therefore, the wall-shaped friction pile according to the present invention is extremely effective in that it can be constructed even on extremely soft ground, which has been extremely difficult in the past.

[Example] Fig. 1 shows an example of the method for driving a wall-shaped friction pile according to the present invention, and shows the process as seen from the side of the planar bag-like body (as seen from the direction parallel to the surface). It is an explanatory diagram. FIG. 2 is an explanatory diagram of a planar bag-like body used therein.

The planar bag-like body 24 used here is made of strong cloth, sheet, etc., and a large number of binding fittings 26 for locally binding both sides of the bag-like body 24 are distributed at appropriate locations, and the bag-like body 24 is The distance between both sides of the spacer is constrained so that it does not widen beyond a certain level. In this embodiment, the binding fittings 26 are arranged alternately (staggered) so as to be at different levels when viewed from a direction perpendicular to the surface of the bag-shaped body.

First, as shown in Figure A, the bag-shaped body 2 is placed on the ground 18.
A slot 20 having a shape corresponding to 4 is formed, and a bag-like body 24 (to which a binding fitting is attached) as described above is inserted into the slot. As a result, the bag-like body 24 is placed in the ground 18.

Next, as shown in Figure B, mortar 22 is press-fitted from the top of the planar bag-like body 24. In extremely soft ground, the pile's own weight may become a problem, so in such cases, foam mortar containing aluminum powder or lightweight mortar using lightweight aggregate may be press-fitted. When the mortar 22 is press-fitted, the binding fittings 26
The bound part does not deform, but the other unbound part bulges due to the press-fitting mortar and deforms so as to push into the surrounding ground. The amount of deformation can be controlled by the amount of mortar press-fitted. If the material is cured under pressure, a wall-like friction pile with a complicated shape can be formed as shown in FIG.

In this way, the ground in front and behind the wall-shaped friction pile is consolidated due to the bulge, increasing the ground strength and pile bearing capacity. The area increases, the resistance to subsidence increases, and it becomes possible to support a large load.

Such a planar bag-like body 24 is extremely convenient when, for example, an open channel or a culvert is passed through extremely soft ground. A plan view in that case is shown in FIG. Open channel 30
A slot having a long width is formed in a direction perpendicular to the installation route, and the bag-like body 24 is inserted into it.
Mortar or the like is then press-fitted so that the unbound portion bulges out and presses into the surrounding ground. In this way, wall-shaped friction piles 32 are formed at appropriate intervals, and open drains 30, underdrains, etc. are constructed on top of the wall-shaped friction piles 32.

The formation position, number, shape, etc. of the binding portions formed in the bag-like body can be changed as appropriate depending on the ground conditions and the like. Although they do not necessarily have to be regularly arranged alternately on different levels, from the viewpoint of overall balance, a shape like the one in the example is preferable.
The bag-like body has "folds" so that the unbound part can expand.
It is also possible to have a structure in which the weave of the cloth is expanded to some extent. Alternatively, the bag-like body may be made of a material that itself can be deformed, such as rubber. If the bag itself is made of a material with high strength, the bending strength can be increased.

As an example of local binding, in addition to the example of using the above-mentioned binding metal fittings, depending on the material of the bag-like body, it may be possible to sew a certain area together, or fix by heat welding, adhesive, or the like.

In addition, to ensure verticality and straightness in the ground, reinforcing materials such as reinforcing bars, iron pipes, or plastic pipes are inserted inside the planar bag.
After that, mortar, concrete, etc. can be press-fitted.

If the distance between the upper and lower bulges is narrow, it is equivalent to increasing the effective diameter of the pile, and the addition of the expansion of the friction surface due to consolidation supports the pile. The force that directly supports the bulge from below has a great influence. In any case, a large supporting force can be achieved with a relatively small amount of mortar.

In the above embodiment, a slot is formed in advance using an excavation device, and the bag-like body 24 is inserted into the slot. However, as shown in FIG. The bag-shaped body 2 is inserted into the pushing member 40 of
4 and hold the tip, and place it on the ground 1.
8, and then only the pushing member 40 is pulled out.

[Effects of the Invention] As described above, the present invention has a structure in which a filling material such as mortar is press-fitted into the locally bound bag-like body located in the ground so that it bulges and pushes into the surrounding ground. Since this is a friction pile driving method, the bulge consolidates the ground around the pile, increasing the ground strength in that area, strengthening the adhesion between the pile surface and the contact soil, and reducing the contact area. Because of this increase, the supporting capacity of the piles becomes extremely large. In addition, because the wall structure has a wall structure in which only the unbound portion of the bag bulges out, a large frictional force can be obtained between it and the ground, unlike conventional simple cylindrical piles. These effects make it possible to develop a sufficiently large bearing capacity, and even in extremely soft ground such as peat layers, which is difficult with conventional construction methods, a pile foundation can be constructed and civil engineering and construction can be carried out on top of it. This has the effect of making it possible to construct structures.

In addition, in the present invention, even when forming a groove in the ground, the cross-sectional area is small and economical.
The materials used are a bag-shaped body and mortar, concrete, etc. that are press-fitted into the bag.Moreover, unlike pouring the entire bag, it only expands locally, which saves on the amount of mortar used. But it's economical.

Furthermore, it has a large degree of freedom, as it can be easily configured with not only flat friction piles but also curved friction piles, so it is possible to construct pile foundations suitable for superstructures, and the surrounding ground can be improved at the same time due to the consolidation effect. There is also.

[Brief explanation of the drawing]

1A and 1B are process explanatory diagrams showing one embodiment of the wall-shaped friction pile driving method according to the present invention, and FIG. 2 is an explanation showing an example of a planar bag-like body used in the present invention. Fig. 3 is a plan view showing an example of construction of a pile foundation using the same, and Fig. 4 is an explanatory view showing another example of inserting the bag-like body into the ground. 18...Ground, 20...Slot, 22...Mortar, 24...Bag-like body, 26...Binding fittings.

Claims (1)

[Claims] 1. A planar bag-like body is provided with a large number of binding parts that locally bind the two sides of the bag-like body, and the bag-like body is placed in the ground and a filling material is placed inside the bag-like body. A method for driving a wall-shaped friction pile, which is characterized by press-fitting the pile, causing the unbound part to bulge out and push into the surrounding ground, and then allowing it to harden.