JPH11269874A - Pile construction method for foundation pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile construction method capable of improving the strength of pipe after construction work by effectively utilizing surplus soil created by the excavation of pile holes. SOLUTION: Hollow concrete or steel piles 4, 5 are driven into ground. In this case, after driving process for piles 4, 5, treated earth D mixed and reformed with a quick lime-based or cement-based additive C, which is hydrate expansive and is kept to an expansive state after drying, is injected from the upper end of the pile 5 to the pile 4 in the lower stage, and the strength of the piles 4, 5 can be compensated by this filling of the treated earth D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the construction of hollow piles used as foundation piles for various types of civil engineering construction.
For example, the present invention relates to a method for constructing a pile for a foundation pile capable of constructing a high-strength foundation pile by utilizing the remaining soil excavated by a spiral auger without discarding the soil.

[0002]

2. Description of the Related Art Concrete or steel pipe piles are cast into the ground as foundation piles, and the pile is held by a suspension type leader that is connected to the boom of a crawler and held in a vertical position as a guide. Basically, the pile is driven by a hammer. Prior to such a casting operation, it is necessary to excavate a pile hole with a spiral auger and press-fit the pile into the pile hole, for example, in order to facilitate pile driving into the ground. Normal.

[0003] In the excavation using a spiral auger, soil and sand are discharged to the ground in accordance with excavation of a pile hole. On the other hand, since a pile having a hollow cylindrical shape is used, construction is generally performed in such a manner that after the pile is cast, the earth removal is buried in the pile, thereby reducing the amount of the remaining soil.

[0004]

However, even though the concrete pile has a hollow structure, the volume occupied by the hollow portion is smaller than that of the excavation hole because the thickness of the pile is large. It is not possible to backfill all of the survived soil. In addition, even when using a thin-walled steel pile, the remaining soil deposited and left on the ground after excavation decreases in density and becomes bulky. is there.

[0005] When all of the remaining soil cannot be backfilled at the site, the remaining soil is carried out from the site and discarded. However, chemicals are often injected with a cement-based soil improvement agent at the pile driving work site, so when performing such soil improvement before excavation, the remaining soil contains cement, etc. Will be. Therefore, the surplus soil cannot be used, for example, for land reclamation or the like, and is currently under regulation to treat it as industrial waste. For this reason,
The surplus soil cannot be disposed of illegally and must be disposed of at a suitable facility or transported to a designated disposal site for dumping, which significantly increases the cost for the contractor.

On the other hand, it is of course possible to reduce the amount of residual soil by burying the residual soil in the casting pile. However, by embedding the residual soil in the pile, the pile is solidified to fill the pile. Some degree of reinforcement effect can be expected.

However, when backfilling the remaining soil in the pile, if the filling pressure is not significantly increased, the pile made of concrete or steel pipe, which has much higher rigidity than earth and sand, is not very effective. Obviously, there is no structure. In order to increase the filling pressure of the remaining soil, it is difficult to simply fill the remaining soil into the pile after placing the pile, and it is necessary to perform an operation such as applying pressure with a special hammer or the like. It is. Therefore, when trying to increase the pile strength by using the residual soil,
A new process for backfilling the remaining soil with a high degree of filling is required, greatly affecting the construction efficiency.

[0008] On the other hand, if the pile is filled with an improved soil by adding a hardener or the like, the effect of reinforcing the pile is expected to be improved. However, when the pile is a hollow body, the interior of the pile at the lower end side is open facing the ground layer, so that there is no blockage between the pile interior and the ground layer. For this reason, even if a material obtained by adding a hardening agent or the like to the remaining soil is injected into the pile, the hardening agent leaks to the ground layer side over time, and the hardening rate of the remaining soil decreases. Therefore, even if the pile is filled into the pile as an improved soil, it cannot be said that a construction body in which the pile strength after construction is continuously compensated can be secured.

As described above, in the conventional pile driving method using a pile made of concrete or steel pipe, a construction method sufficient to improve the strength of the pile by using the remaining soil has not been established.

An object of the present invention is to provide a pile construction method capable of improving pile strength after construction by effectively utilizing residual soil generated by excavation of a pile hole.

[0011]

According to the present invention, there is provided a method for constructing a pile for a foundation pile, comprising the steps of constructing a pile of hollow concrete or steel plate as one or a plurality of piles and placing the pile in the ground. Injecting treated soil mixed and modified with quicklime or a cement-based additive, which is hydrated and expandable after the pile placing step and is kept in an expanded state after drying, from the upper end of the pile It is characterized by filling.

In this construction method, the pile hole for placing the pile is excavated in advance, and the earth and sand discharged by the excavation is left on the ground surface as residual soil, and the residual soil is collected as the treated soil. Is also good.

[0013] Further, a pile having a cap at the lower end of one pile which is firstly cast into the pile hole and which blocks a hollow portion of the pile from the ground side can be used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing, in order, the steps up to the placement of a pile in the construction method of the present invention.

In the figure, a suspension type reader 1b attached to a boom 1a of a crawler type pile driver 1 installed on the ground.
In addition, a wire 1c operated by a winch (not shown) provided in the pile driver 1 is provided, and an auger for excavation and a hammer for pile driving can be suspended from the wire 1c.

FIG. 1 (a) shows a spiral auger 2 connected to a wire 1c and a driving device 2 attached to a pile driver 1.
a is provided, and the auger 2 is driven by the driving device 2a.
Rotates and excavates in the ground to excavate the pile hole A. In the excavation using the spiral type auger 2, the earth and sand discharged from the pile hole A is left on the ground as residual soil B.

After excavation of the pile hole A, the hammer device 3 for hitting is connected to the leader 1b so as to be able to ascend and descend with the leader 1b as shown in FIG.
The hammer device 3 is connected to the wire 1c. And
After the pile 4 is raised by a crane device (not shown) and its lower end is inserted into the pile hole A, the pile 4 is inserted into the pile hole A while intermittently hitting the pile 4 with the hammer device 3. I will cast it.

The pile 4 may be a concrete or steel pipe hollow pile, and the hammer device 3 may have a conventionally known simple structure for hitting the upper end of the pile 4. In this embodiment, a cap 4a for driving is provided at the lower end of the pile 4 to be driven first, and the hammer device 3 is connected to the upper end of the pile 4 and the cap 4a.
A description will be given assuming that both of a and b are configured to give a blow.

FIG. 2 is a schematic longitudinal sectional view showing a structure for hitting the pile 4 by the hammer device 3.

The pile 4 is made of hollow concrete, and a circular trough-shaped cap 4a made of a steel plate is extrapolated at the lower end thereof. This cap 4a
It has a peripheral wall 4 a-1 having an inner diameter larger than the outer diameter of the pile 4, and can move freely without being restricted by the pile 4. The height of the peripheral wall 4a-1 has a dimension longer than a predicted stroke of driving the hammer device 3 in the ground.

The hammer device 3 includes a pile hammer 3b inside a housing 3a suspended from a wire 1c, and a drop hammer 3c below the pile hammer 3b. Winch 3d at the upper end of the housing 3a
And two cylinders 3e and 3f on the side, and a wire 3 connected to each of these cylinders 3e and 3f.
g and 3h are pile hammer 3b via winch 3d
And the drop hammer 3c.

In the hammer device 3 having such a configuration, by appropriately interlocking the winch 3d and the cylinders 3e and 3f, the drop hammer 3c precedes the impact on the cap 4a, and thereafter the pile hammer. 3
It can be operated so as to repeatedly hit the upper end of the pile 4 by b. Therefore, the pile 4 to be driven into the pile hole A moves first while the cap 4a at the lower end moves downward and excavates, and thereafter the pile 4 is hit from above and moves while pushing down the cap 4a downward. .

Returning to FIG. 1, when the first pile 4 is driven by driving the hammer device 3, the second pile 5 is inserted into the pile hole A as shown in FIG. These are cast integrally with the lower pile 4. In this driving, the pile 5 is hit by the pile hammer 3b, and the cap 4a at the lower end of the pile 4 is hit by the drop hammer 3c. When the piles 4 and 5 are press-fitted, the cap 4a is hit with the drop hammer 3c and the amount of subsidence at this time is measured, as shown in FIG. The power is checked and the casting is completed.

The above is the step of driving the two piles 4 and 5 into the ground, and when this step is completed, the pile driving machine 1 is moved to another driving place, as shown in FIG. The pile is driven in the same way as the pile. As for the piles 4 and 5 that have been cast, since the inside is hollow at the lower end of the lower pile 4, as shown in FIG. Useful for reinforcement of 4,5.

The residual soil B discharged in the step of excavating the pile hole A by the auger 2 is mixed and mixed reformed with the additive C by the processing tank 6 installed on the ground to form a processed soil D. Are poured into piles 4,5. The processing tank 6 is provided with an agitator 6a that is rotationally driven by a motor (not shown) and a hopper 6b provided with an on-off valve 6c in the middle.

Here, as the additive C, quicklime (calcium oxide) can be used. This quicklime is hydrated and has a property that its volume expands when it contains moisture, and after drying, it is kept in this expanded bulk. For this reason, quicklime was added as an additive C to the treated soil D by stirring and mixing with the residual soil B, and the treated soil D was dropped and injected from the upper end of the upper pile 5 from the hopper 6b, and supplied from the moisture contained in the residual soil B or from the ground side. The additive C can be expanded by moisture. Then, since the additive C remains expanded even after the residual soil B is dried, the overall filling degree at the time of injection can be increased.

When filling the treated soil D, since the lower end of the pile 4 is closed by the cap 4a, the additive C contained in the treated soil D does not leak into the ground together with moisture, and the pile 4, 5 is filled with the treated soil D. If the treated soil D is preliminarily treated to one having good sandiness, the piles 4 and 5 can have a more dense filling degree that does not include voids.

After the curing period after the filling of the treated soil D, it gradually dries due to the sedimentation and evaporation of the contained water, and as shown in FIG. At the same time, the treated soil D remains. The treated soil D is densely distributed in a state of being densely packed in the piles 4 and 5 due to the expansion of the additive C, and is filled so that the piles 4 and 5 become solid bodies. Since the hardness can also be increased, the mechanical strength of these piles 4 and 5 can be improved.

The residual soil B discharged by the excavation of the pile hole A can be used as a reinforcing material for the piles 4 and 5 by recovering the residual soil B with the additive C as the treated soil D. Construction of piles becomes possible. In addition, since the remaining soil B is backfilled, it is not necessary to carry out and dispose of a large amount of the remaining soil from the site, which can greatly contribute to cost reduction.

It is a matter of course that similar construction can be performed even with a normal hollow pile having no cap 4a at the lower end of the pile 4. In this case, since the cap 4a is not provided, there is a possibility that the improving agent C contained in the filled treated soil D may leak into the ground. Therefore, it is preferable to increase the amount of the additive C.

In the excavation by the auger 2, the remaining soil B is discharged. However, even if other construction methods are used, the soil is removed by other excavation work and treated using the sediment deposited on the site. Construction that can be modified into soil is possible.

[0032]

According to the first aspect of the present invention, the treated soil in which the hydration-swelling additive is mixed is injected into the hollow pile, so that the treated soil can be utilized by utilizing the expansion of the additive even after drying. The whole pile can be densely packed, and a stable foundation pile with high rigidity can be obtained.

According to the second aspect of the present invention, the residual soil discharged during the excavation of the pile hole can be reformed and reused as the treated soil.
The burden of removing and disposing of surplus soil from the site is reduced, and costs can be reduced.

According to the third aspect of the present invention, since the lower end side of the pile is closed by the cap, there is no leakage of the treated soil or seepage of the mixed improving agent, and the strength compensation by the treated soil is prevented from deteriorating. .

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view sequentially showing steps up to pile placement in a pile driving method according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part schematically showing a hammer device and a pile applicable to the pile driving method of FIG.

FIG. 3 is a schematic view showing a step of injecting a treated soil obtained by modifying a residual soil with an additive into a pile.

FIG. 4 is a schematic view showing a state of placing a pile which is internally filled with treated soil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pile driver 2 Auger 3 Hammer device 3b Pile hammer 3c Drop hammer 4 Pile 4a Cap 5 Pile 6 Stirring tank 6a Agitator 6b Injection pipe 6c Open / close valve A Pile hole B Residual soil C Additive D Treated soil

Claims (3)

[Claims] In the construction of a foundation pile for placing one or a plurality of hollow concrete or steel piles into the ground, the pile is hydrate-expandable after the pile placing step. A method for constructing a pile for a foundation pile, in which treated soil mixed and modified with quicklime or a cement-based additive that is kept in an expanded state after drying and injected from the upper end of the pile. 2. The foundation pile according to claim 1, wherein a pile hole into which the pile is to be cast is excavated in advance, and the earth and sand discharged by the excavation is left on the ground side as residual soil, and the residual soil is collected as the treated soil. Pile construction method. 3. A pile for a foundation pile according to claim 2, wherein a pile having a cap for blocking a hollow portion of the pile from the ground side is used at a lower end of one pile first driven into the pile hole. Pile construction method.