JP2005002635A - Foundation pile and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation pile which is excellent in workability, economy and pile performance, and which prevents or minimizes the production of excavated surplus soil to be disposed of in the whole foundation pile, by effectively utilizing characteristics of both a steel pipe pile to be constructed as a non-earth-removal pile and a cast-in-place pile to be constructed in the lower part of the steel pipe pile, and a manufacturing method for the foundation pile. <P>SOLUTION: A steel pipe 1 penetrates ground up to a prescribed depth without earth removal in a state wherein a lower end is closed with a closing member such as a rotary head 2. The rotary head 2 at the tip of the steel pipe 1 is removed, and recovered through the inside of the steel pipe 1. When lower ground is excavated through the inside of the steel pipe 1 whose end is opened, and concrete 7 is placed by inserting a cage 5 into a pile hole 4, so that the cast-in-place pile can be constructed below the steel pipe pile. The excavated surplus soil in the excavation of the pile hole 4 is infilled into the upper steel pipe 1 in an as-is state or the state of being stabilized by means of cement etc. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundation pile composed of a steel pipe pile constructed with no soil and a cast-in-place pile connected to the lower side thereof, and a manufacturing method thereof.
[0002]
[Prior art]
As a foundation pile, a soilless pile (for example, refer to Patent Document 1) that pushes the soil of the place where the pile is to be pushed downward and laterally and press-fitted into the portion, and then a ready-made pile is buried in that portion after removing the earth and sand beforehand. There is a soil pile.
[0003]
In general, cast-in-place piles are the latter soil-extracted piles, but an invention that inserts a steel pipe into a pre-drilled pile hole and fills the inside and outside of the steel pipe with soil cement with cement added to the excavated soil is a patent document. 2 and Patent Document 3.
[0004]
Also, in Patent Document 4, after placing a large-diameter steel pipe pile with an open end to the required depth, the earth and sand in the steel pipe pile or the steel pipe sheet pile is removed, and a cast-in-place concrete pile is constructed below the steel pipe. A composite foundation pile in which an upper steel pipe pile and a lower cast-in-place concrete pile are integrated is described.
[0005]
[Patent Document 1]
JP 2001-31147 A [Patent Document 2]
JP-A-60-148919 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-234531 [Patent Document 4]
JP 2002-004271 A
[Problems to be solved by the invention]
In the case of soilless piles using steel pipes, various types of steel pipes with drilling blades and rotary blades for rotational penetration have been developed at the tip of the pipe, and there are few problems with noise and vibration like the hammering method, In addition, there is an advantage that construction without soil can be performed. In particular, steel pipe piles have higher strength and higher reliability than on-site piles.
[0007]
In addition, in soilless construction, the piles are pressed in by pushing the earth and sand of the place where the piles are installed to the side and downward, which also has the effect of compacting the surrounding ground. In addition to improving the vertical frictional force, the peripheral frictional force is also increased.
[0008]
However, if the frictional force with the ground during rotation penetration is large, a large torque is required for rotation penetration, and there are rocks or other obstacles in the intermediate layer that does not go to the support ground, or the intermediate layer is hard In some cases, the construction becomes difficult and the construction cost increases.
Moreover, it exists in the tendency for the pile diameter which can be constructed in relation to ground conditions etc. to be limited.
[0009]
On the other hand, the inventions described in Patent Document 2 and Patent Document 3 can reduce the amount of waste disposal of excavated soil to some extent by backfilling the excavated soil in the form of soil cement, but it is more than the outer diameter of the steel pipe to be inserted. Therefore, there is a problem that a large amount of excavated soil is generated, and excavated residual soil that cannot be backfilled is generated, and the pile diameter becomes larger than necessary.
[0010]
In addition, since soil cement is filled inside and outside the steel pipe, the amount of cement is required and the cost is increased.
[0011]
The invention described in Patent Document 4 simply arranges steel pipe piles and cast-in-place concrete piles up and down, and compensates for changes in pile types and pile cross-sections with joint steel pipes arranged at these connections. It does not consider soil removal, and there is a problem of disposal of excavated residual soil. Depending on the ground conditions, the peripheral friction force in the steel pipe pile part cannot be expected so much.
[0012]
The present invention uses a steel pipe pile constructed as an earthless pile and creates a cast-in-place pile at the lower part of the steel pipe pile so that the upper part of the steel pipe pile exhibits the advantages of the earthless pile. On the other hand, a foundation pile that can prevent or minimize the excavation residual soil that needs to be disposed of as a whole foundation pile, has excellent workability and economic efficiency, and also has excellent pile performance, and a manufacturing method thereof. It is intended to provide.
[0013]
[Means for Solving the Problems]
The foundation pile which concerns on Claim 1 of this application consists of a steel pipe pile penetrated in the ground by non-exhaust soil, and a cast-in-place pile connected to the downward direction.
[0014]
The upper steel pipe pile that constitutes the foundation pile of the present invention is one that has been penetrated into the ground without draining, and the penetration method may be any of press-fitting, screwing, and driving depending on the ground conditions.
[0015]
Among these, the screwing, that is, the method of rotating and penetrating the steel pipe while applying downward pressure has an advantage of less noise and vibration. In that case, if necessary, by providing a drilling blade, a spiral rotary blade, or the like at the tip of the steel pipe, the resistance received from the ground is reduced and the construction is facilitated.
[0016]
In addition, this steel pipe pile is inserted while pushing the soil of the place where the pile is installed downward or sideways, but it is not necessary to push all the soil, even if a part of it is taken into the pile at the time of penetration Good. By doing so, the penetration speed can be adjusted.
[0017]
That is, the steel pipe pile in the present invention is excavated with a pile hole having a diameter larger than the pile diameter before penetration, or after the penetration, the excavated earth and sand is taken out to the outside as it is usually called “no soil removal”. It is penetrated in a way that is not necessary.
[0018]
Cast-in-place piles can be built through steel pipe piles at the top. Generally, after excavating toward the support ground with an excavator such as an earth auger and inserting a reinforcing bar into the excavated hole, concrete However, the material and shape of the cast-in-place pile are not particularly limited, and various conventional cast-in-place piles can be applied.
Further, if necessary, an enlarged bulb portion or the like can be provided at the tip.
[0019]
Regarding the load transmission between the upper steel pipe pile and the lower cast-in-place pile, the lower part of the steel pipe and the cast-in-place pile overlap each other for a predetermined length. For example, when the cast-in-place pile is cast-in-place concrete, A reinforcing bar extending into the steel pipe can be provided, and a band-like or rib-like protrusion can be provided at the lower part of the steel pipe as required. In this case, it is conceivable that the concrete is filled only in the lower part of the steel pipe or the outer surface part of the lower part of the steel pipe is excavated and the inner and outer surfaces of the steel pipe are filled with concrete.
[0020]
The invention according to claim 2 is the foundation pile according to claim 1, wherein the steel pipe is filled with excavated residual soil, soil cement or concrete.
[0021]
In the lower cast-in-place pile part, residual soil is generated by excavation at the time of creation. The amount of processing can be greatly reduced, and the strength of the foundation pile can be increased by filling the inside of the steel pipe pile.
[0022]
When there is little excavation surplus soil, concrete may be filled in the steel pipe, or the concrete may be filled with soil cement or soil cement or excavation surplus soil.
[0023]
If the excavated soil generated in the construction of the cast-in-place pile is filled into the steel pipe after intruding into the ground without excavating the top steel pipe pile part with the tip closed, theoretically, the upper steel pipe pile part About the steel pipe of
[Remaining excavated soil] ≤ [Volume in steel pipe]
If the steel pipe having the length of the steel pipe is used, all of the excavated residual soil can be filled in the steel pipe and processed.
[0024]
The manufacturing method of the foundation pile which concerns on Claim 3 of this application is the state which block | closed the said steel pipe to the predetermined depth in the state which obstruct | occluded the lower part of the steel pipe with the closure member, and cancel | release the obstruction | occlusion by the said closure member, and this steel pipe It is characterized by excavating the lower ground through the interior of the steel pipe and creating a cast-in-place pile below the steel pipe.
[0025]
In the state where the lower part of the steel pipe is closed, the ground around the steel pipe is tightened by pushing the steel sand and the volume of the steel pipe including the inside of the steel pipe sideways or downward while the steel pipe pile penetrates into the ground. There is an effect of hardening, and since there is no gap between the outer surface of the steel pipe and the surrounding ground, there is no need to backfill or fill that part, and the outer surface of the steel pipe and the compacted earth and sand are in direct contact with each other. The ground reaction force performance is improved, and the peripheral support force by peripheral friction is also increased.
[0026]
The predetermined depth at which the steel pipe penetrates into the ground is not particularly troublesome for the penetration of the steel pipe without soil removal, and it also has a particular trouble for the disposal of the soil due to the cast-in-place piles formed below it. For example, the depth can be determined by the amount of excavated soil generated in the formation of cast-in-place piles, the workability of both steel pipe piles and cast-in-place piles according to the ground conditions, and the balance of economy.
[0027]
The closing member is not particularly limited, such as a flat plate shape, a cone shape with a sharp tip, etc., but in order to create a cast-in-place pile through the steel pipe, it can be removed and removed after the steel pipe penetrates, or You can use something that opens in a specific direction. The closing / opening / closing system of the closing member may be mechanically attached / detached or opened / closed, or can be removed or opened by applying force through the steel pipe. It may be a thing.
[0028]
In addition, by providing an excavating blade or blade on the surface of the closing member, it is easy to penetrate the steel pipe, or a rod passing through the steel pipe is attached to the rear end of the closing member so that the closing member alone or together with the steel pipe can be rotated. Things can also be used. Moreover, after removing a closure member from the front-end | tip of a steel pipe, it can also utilize for the excavation in the construction of a cast-in-place pile.
[0029]
In the manufacturing method of the foundation pile according to claim 4 of the present application, the steel pipe is penetrated into the ground to a predetermined depth in a state where the lower part of the steel pipe is closed by the closing member, and then the closing member is recovered through the steel pipe, The ground is further drilled through the inside of the steel pipe, and a cast-in-place pile is created below the steel pipe.
[0030]
By using a closing member with an outer diameter smaller than the inner diameter of the steel pipe, or by using a closing member that can be mechanically expanded or contracted, the closing member can be recovered through the steel pipe after it has penetrated into the ground. In this case, the closing member can be diverted one after another.
[0031]
In particular, in the case of using a cone-shaped closing member provided with a drilling blade or a spiral blade in order to improve penetration, it is possible to collect and divert a relatively expensive closing member, thereby reducing the construction cost. I can plan.
[0032]
The invention according to claim 5 is the method of manufacturing a foundation pile according to claim 3 or 4, wherein the predetermined depth for press-fitting the steel pipe is set to a depth before the intermediate layer having a ground strength of a predetermined level or more. It is a feature.
[0033]
The intermediate layer herein refers to a layer having a certain level of ground strength at a depth that does not reach the support layer, and can be determined, for example, by comparing N values at each depth of the target ground. However, whether or not a certain N-value layer is regarded as an intermediate layer depends on the required pile length, the diameter of the steel pipe to be press-fitted, the performance of the construction machine, and the like, and it is necessary to consider the workability and the economic efficiency.
[0034]
The invention according to claim 6 is the method for manufacturing the foundation pile according to claim 3, 4 or 5, wherein the steel pipe is penetrated into the ground while rotating the steel pipe and / or the closing member. It is what.
[0035]
As described above, the penetration of the steel pipe into the ground is low noise and vibration due to the rotation penetration, and is excellent in workability. In this case, a method of rotating only the steel pipe and a method of rotating the closing member and the steel pipe at the same time are conceivable. In addition, a rotating rod is connected to the closing member provided with a drilling blade and the steel tube is rotated by rotating only the closing member. A method of press-fitting in such a manner as to follow the closing member without causing it to occur is conceivable.
[0036]
The invention according to claim 7 is the method of manufacturing a foundation pile according to claim 3, 4, 5, or 6, wherein the step of taking earth and sand from the blocking member or between the blocking member and the steel pipe into the steel pipe is provided. It is characterized by having.
[0037]
By providing a hole that can be opened and closed in the closing member, reducing the size of the closing member itself, and separating the closing member from the tip of the steel pipe, the earth and sand can be taken into the steel pipe during the penetration of the steel pipe. By doing so during penetration, the penetration rate can be adjusted.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention, and shows a construction procedure corresponding to a columnar diagram of the ground relating to an N value on the left side in the drawing. In this example, it is assumed that the upper part of the ground is mainly soft ground having an N value of 10 or less, and has an intermediate layer having an N value of about 40 at a depth that does not reach the support layer having an N value of about 50.
[0039]
The construction procedure in this embodiment is as follows.
(1) Installation of rotating head (see Fig. 1 (a))
The rotary head 2 that is a closing member for closing the tip of the steel pipe 1 is set at the pile installation position. In the present embodiment, the rotary head 2 has a cone shape with a sharp tip, and has a form suitable for rotational penetration in which two spiral wings are provided on the outer peripheral surface.
That is, in the present embodiment, the rotary head 2 has a function as a lid that prevents intrusion of earth and sand into the steel pipe 1 and a function that facilitates the rotation penetration of the steel pipe 1.
[0040]
(2) Installation of steel pipe and rotation penetration (see Fig. 1 (a) to (b))
Next, the steel pipe 1 which comprises an upper steel pipe pile part is set on the rotation head 2 as a closure member. The connection structure with the rotary head 2 is not particularly limited. For example, a structure that engages in a direction opposite to the rotation direction at the time of rotation penetration or a structure that can be attached and detached using elasticity such as a spring can be used.
In this state, the steel pipe 1 is rotated and penetrated into the ground while rotating around the axis of the steel pipe 1 using a rotating device such as a casing driver. In addition, as a method of rotating penetration, for example, a connecting portion of a rotating rod (not shown) is provided at the rear of the rotating head 2, and the rotating head 2 is rotated alone or together with the steel pipe 1 by the rotating rod. It is also possible to rotate and penetrate.
In the present embodiment, a spiral auxiliary wing 1 a for facilitating rotational penetration is also attached to the lower part of the steel pipe 1.
[0041]
(3) Steel pipe joint construction (see Fig. 1 (c))
If the steel pipe 1 is rotated and penetrated to a depth corresponding to the length of the steel pipe 1, the next steel pipe 1 is connected to the upper part by welding or the like. When a single steel pipe 1 is sufficient, this operation is not necessary. When three or more steel pipes 1 are required, this operation is repeated.
[0042]
(4) Stabilizing liquid injection (see Fig. 1 (d))
When reaching the intermediate layer where the rotation penetration becomes difficult, the rotation penetration of the steel pipe 1 is terminated, and a stable liquid 3 such as bentonite mud is injected into the steel pipe 1.
The stabilizing liquid 3 is used to stabilize the hole wall during excavation of the pile hole 4 (see FIG. 1 (f)) in the construction of a cast-in-place pile deeper than that, but the rotary head 2 is removed in this embodiment. Since it also has a function of stabilizing the portion where the rotary head 2 is in contact with, the stabilizing liquid 3 is injected before the rotary head 2 is collected.
[0043]
(5) Rotating head recovery (see Fig. 1 (e))
The rotary head 2 that is detachable from the steel pipe 1 is removed from the tip of the steel pipe 1 and collected through the inside of the steel pipe 1. This rotary head 2 can be used for the construction of other foundation piles.
[0044]
(6) Earth drilling (see Fig. 1 (f))
Through the inside of the steel pipe 1, the pile hole 4 is excavated with an earth drill or the like in the same manner as a normal cast-in-place pile construction. Further, in the vicinity of the support layer, a diameter-enlarged portion for creating an enlarged bulb portion is excavated as necessary.
[0045]
(7) Reinforcing bar, concrete placement (see Fig. 1 (g))
Through the inside of the steel pipe 1, a reinforcing bar 5 is inserted into the pile hole 4, and concrete 7 is placed by a tremy pipe 6 or the like. At this time, by making the main bar-like portion of the reinforcing bar 5 protrude into the steel pipe 1, the integrity of the upper steel pipe pile portion and the lower cast-in-place pile portion can be improved, and the stress transmission can be made smooth. .
[0046]
(8) Filling the excavated soil (see Fig. 1 (h))
Filling the hollow steel pipe 1 with the excavated residual soil 8 when excavating the pile hole 4 for cast-in-place pile construction as it is or after adding a hardener such as cement, Use as much of the excavated soil as possible, and reduce the amount of residual soil as much as possible.
[0047]
If processing of excavated soil is not particularly problematic, or if the pile length of the steel pipe pile is long and cannot be filled with excavated surplus soil, it may be filled with concrete or left hollow if necessary. .
[0048]
As described above, a steel pipe pile whose upper part is penetrated with no-draining soil and a foundation pile whose lower part is a cast-in-place pile are manufactured.
[0049]
In this embodiment, the tip of the steel pipe 1 is set to a depth at which the steel pipe 1 can be relatively easily press-fitted without drainage by rotational penetration, that is, before the intermediate layer where the N value becomes large. The tip position of the steel pipe can also be determined by other factors such as ground conditions, depth to the support layer, distribution of steel pipe pile parts and cast-in-place pile parts.
[0050]
【The invention's effect】
The present invention is a steel pipe pile that is relatively easy to construct with low noise and low vibration due to rotational penetration, etc. or capable of non-soil construction up to a possible depth, and is a cast-in-place pile for further depths. Efficient construction is possible at low cost on the machine.
[0051]
If the residual soil generated in the construction of the lower in-situ pile is backfilled in the steel pipe pile, the total excavated residual soil can be prevented or minimized.
[0052]
The steel pipe pile which comprises the upper part of a foundation pile is a pile with high intensity | strength and high reliability compared with a site pile, and can be reliably made to resist the big horizontal force and bending which act on the upper part of a pile.
[0053]
Also, in the construction of steel pipe piles, the steel pipe with the closed end is pressed into the ground by a method such as rotary penetration, so that the surrounding earth and sand are pressed sideways and downward, and the surrounding ground is compacted. can do. In this case, there is no gap in the outer periphery of the steel pipe, so there is no need for backfilling around the steel pipe, and the horizontal reaction force performance from the compacted ground is improved and the peripheral frictional force is increased. The vertical supporting force is also improved.
[0054]
On the other hand, in-situ piles can be constructed almost without being influenced by the ground conditions, and even in the ground conditions where it is difficult to penetrate the steel pipes to the support layer, the in-situ piles must be created under the steel pipe piles to the support layer. And a high tip support force can be obtained with concrete having excellent compressive strength. In addition, since it is relatively easy to create the enlarged bulb portion, it is possible to obtain a higher tip support force.
[0055]
In the foundation pile manufacturing method of the present invention, the closing member that closes the lower part of the steel pipe is structured to be separable from the steel pipe. For example, it is assumed that a cone-shaped member with a reduced diameter at the tip is provided with a drilling blade or a drilling blade. The steel pipe can be smoothly penetrated, and can be recovered and reused, or can be used for excavation for construction of a cast-in-place pile to be formed below.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a construction procedure in one embodiment of the present invention together with an N-value columnar diagram of the ground.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Steel pipe, 1a ... Auxiliary blade, 1b ... Inner surface protrusion, 2 ... Rotating head (blocking member), 2a ... Blade, 3 ... Stabilizing liquid, 4 ... Drilling hole, 4a ... Diameter expansion part, 5 ... Reinforcing bar, 6 ... Tremy tube, 7 ... concrete, 8 ... remaining excavated soil

Claims (7)

A foundation pile comprising a steel pipe pile penetrated into the ground with no soil and a cast-in-place pile connected below. The foundation pile according to claim 1, wherein the steel pipe is filled with excavation residual soil, soil cement or concrete. After the steel pipe is penetrated into the ground to the specified depth without drainage with the lower part of the steel pipe closed by the closing member, the blockage by the closing member is released, and the lower ground is excavated through the inside of the steel pipe. A cast-in-place pile is created below the steel pipe. With the lower part of the steel pipe closed with a closing member, the steel pipe is penetrated into the ground to a predetermined depth with no soil, and then the closing member is recovered through the steel pipe and further below the ground is excavated through the steel pipe. Then, a cast-in-place pile is created below the steel pipe. The manufacturing method of the foundation pile of Claim 3 or 4 which makes the predetermined depth which press-fits the said steel pipe the depth to the near side of the intermediate | middle layer which has ground strength more than predetermined. The method for manufacturing a foundation pile according to claim 3, 4 or 5, wherein the penetration of the steel pipe into the ground is performed while rotating the steel pipe and / or the closing member. The method for manufacturing a foundation pile according to claim 3, further comprising a step of taking earth and sand into the steel pipe from between the closing member or between the closing member and the steel pipe.

Images