JP2004218378A - Removing method for existing pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing an existing pile, enabling a separation to cut off a frictional force between an existing pile and the natural ground even in a narrow place or a low-head space by a mechanized execution using a small apparatus. <P>SOLUTION: Surrounding the existing pile, an object for removal, an injection rod 8 with a jet hole 8a of an ultra-high pressure water on its tip end is inserted into the ground. By spraying the ultra-high pressure water during the intrusion or pulling-up process, the ground is cut into a panel-shape, which is repeated successively to form separation faces 9 of polygonal shape for surrounding an entire or a major part of the existing pile 1. Thereafter, the existing pile 1 is pulled out and removed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for removing a building or a pile that supports the building, and more particularly to a method for pulling and removing an existing pile that can be machined even in a low head space in underpeening work or the like.
[0002]
[Prior art]
Conventionally, various methods have been proposed as a method of removing an existing pile that supports a building or a building. When the pile length is short, these pile removal methods can be lifted directly using jacks, vibro hammers, cranes, etc., but when the pile length is long, first the existing pile and the ground The method of pulling out the pile after cutting the edge to cut the peripheral frictional force is generally used.
[0003]
For example, in Patent Document 1 below, a two-axis driven earth auger machine is used, and a drilling casing provided with a cutter at the tip that can dig around the target pile is attached to one of the axes, and the other axis is attached to the other axis. A method is proposed in which an auger screw is arranged, the ground around the pile is cut with the excavating casing, and at the same time excavation and excavation is performed with the adjacent auger screw, the circumference of the pile is excavated to the required depth, and then the pile is pulled out Has been.
[0004]
Moreover, in the following Patent Document 2, an existing concrete pile is first cored with a lock auger, and then built while rotating the casing so as to surround the periphery of the existing concrete pile. A method of drawing an existing concrete pile by cutting the edge between the concrete pile and the ground is disclosed.
[0005]
In the cited document 3 below, a casing having a diameter larger than the outer diameter of the existing pile is buried so as to surround the existing pile while rotating at least to the depth of the existing pile, and then penetrates along the central axis of the existing pile. After drilling the hole, insert a long suspension material into the through-hole from above, and insert the lower end of the long suspension material slightly beyond the bottom of the through-hole, and then below the long suspension material A removal method is disclosed in which the tip is enlarged and hooked to the bottom end of the existing pile, and then the existing pile is pulled out simultaneously by pulling up the long suspension material from above.
[0006]
In the following Patent Document 4, a jig whose cross-section is formed in a U shape with an opening, longer than the length of a pile to be pulled out by a steel sheet pile or a rope, and narrower than the width of the pile; A water jet device having a casing fixed to the lower end portion of the jig, a plurality of high pressure water nozzles attached to the outer periphery of the casing, and a high pressure water pipe connected to the upper end portion of the high pressure water nozzle. Set so as to surround a part of the outer peripheral surface of the pile to be pulled out, fix the vibro hammer to the upper end of the jig, inject the water jet from the high pressure water nozzle, and move the water jet device along the length direction of the pile The pile is pulled out with a vibro hammer to cut the peripheral frictional force between the pile and ground, and then the water jet device is pulled up and then the pile is pulled out. It has been disclosed.
[0007]
[Patent Document 1]
JP 2001-226967 A [Patent Document 2]
JP 2001-303570 A [Patent Document 3]
JP 2000-64283 A [Patent Document 4]
Japanese Patent Laid-Open No. 9-268555
[Problems to be solved by the invention]
However, the casing that cuts the peripheral frictional force between the existing pile and the natural ground (the casing with a water jet in Patent Document 4), etc., can be constructed using a large lifting machine or a biaxially driven earth auger machine. For this reason, there is a problem that even if the construction can be performed with a sky head without any restriction on the sky, the construction cannot be performed due to the restriction of the height dimension in a low head space with an obstacle or the like on the upper part. Specifically, in a building or building supported by a pile foundation, the existing pile is replaced with a new pile because the existing pile becomes an obstacle to an underground structure such as a newly constructed tunnel. In the case of underpinning to be performed, a low sky head space will be created in the building or the basement directly under the building, and the existing pile will be removed, but in the case of pile removal under such conditions, the method described above It is virtually impossible to adopt
[0009]
Therefore, the removal of the existing piles in the above-described underpeening work was performed by a deep foundation method with a diameter in consideration of a space in which the manual lifting work can be performed around the existing piles. Specifically, around the existing piles, excavating and breaking the piles along the depth direction from the head of the pile while removing the existing piles by manually maneuvering with the liner plate for deep foundation. The pile was removed by the procedure of removing the liner plate for deep foundation while backfilling.
[0010]
However, in the case of such a manual pile removal method, it takes a lot of days and labor to remove the pile, so a method that allows mechanized construction even under low head conditions is strongly desired. It was.
[0011]
Therefore, the main problem of the present invention is to enable edge cutting for cutting the peripheral friction force between the existing pile and the natural ground by mechanized construction using a small device even in a narrow place or low head space. The purpose is to propose a method for removing existing piles.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, as the present invention according to claim 1, around the existing pile to be removed, an injection rod having an ultrahigh-pressure water injection port at the tip is inserted into the ground, and the penetration process or After repeating the process of cutting the ground into a panel shape by jetting ultra-high pressure water in the pulling process, a polygonal edge cut surface is formed so as to surround the entire circumference or most of the existing pile, and then the existing pile A method for removing an existing pile is provided, which is characterized by pulling out and removing the pile.
[0013]
In the present invention according to the first aspect, the edge cut surface is formed by jetting ultrahigh pressure water from the jet rod. The injection rod has a structure that can be added, can penetrate into the ground even under low head and narrow space conditions, and forms a cutting edge in a wide panel-like area from the rod penetration position Therefore, it is possible to efficiently remove piles.
[0014]
As the present invention according to claim 2, three or more penetration points of the injection rod are set on the outer periphery of the existing pile, and a section from one rod penetration point to an adjacent rod penetration point is formed into a panel shape by injection of ultrahigh pressure water. A method for removing an existing pile according to claim 1 is provided.
[0015]
As the present invention according to claim 3, two or more penetration points of the injection rod are set on the outer periphery of the existing pile, and between the rod penetration points, an edge cutting surface formed by super high pressure water injection from one rod penetration point; The method for removing an existing pile according to claim 1, wherein cutting is performed in a panel shape by intersecting or continuing an edge cutting surface formed by jetting ultrahigh pressure water from the other rod penetration point. According to this method, the number of penetrations of the injection rod can be reduced.
[0016]
As the present invention according to claim 4, there is provided the method for removing an existing pile according to any one of claims 1 to 3, wherein the injection of the ultra-high pressure water is carried out with accompanying compressed air. It is possible to increase the cutting distance by causing compressed air to accompany the ultrahigh pressure water.
[0017]
According to a fifth aspect of the present invention, there is provided a method for removing an existing pile according to any one of the first to fourth aspects, wherein the injection rod uses a single pipe, a double pipe or a triple pipe. When compressed air is not accompanied, a single tube is used, and when compressed air is accompanied, a double tube or a triple tube is used. The double pipe used in the JSG method can be used as the double pipe, and the triple pipe used in the column jet grouting method can be used as the triple pipe.
[0018]
The present invention according to claim 6 provides the method for removing an existing pile according to any one of claims 1 to 5, wherein the removal of the existing pile is performed while alternately repeating the pulling up and the cutting for the pulling up. Is done. Since the existing piles cannot be lifted and removed at a low height in a low-headspace, removal is performed while alternately repeating the pulling and cutting of the lifted portion.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
(Underpinning)
For example, underpinning, where the existing pile removal method is suitably applied, under the condition that there are ground structures such as buildings and elevated roads supported by the pile foundation on the ground, tunnels and culverts, etc. In the case of building, the load on the ground structure is replaced by a new pile, and the present invention is employed to remove the existing pile.
[0021]
Specifically, underpinning will be described in detail based on FIG. 1. As shown in FIG. 1A, when there is a building 2 supported by a pile foundation, first, as shown in FIG. 1B. Next, excavate under the ground of the building 2 and place new piles 3, 3. And as shown in FIG.1 (C), it backfills with the spread sand 4, and the replacement version 5 supported by the new piles 3, 3, ... is constructed | assembled. Next, as shown in FIG. 1 (D), if the building load is transferred to the replacement plate 5 by a jack after the floor sand 4 is removed, the receiving load is received as shown in FIG. 1 (E). The existing piles 1, 1... Are removed in the space between the replacement plate 5 and the root cutting bottom, and then the tunnel 6 is built in the ground sandwiched between the new piles 3, 3.
[0022]
(Removal of existing piles)
When the existing pile 1 is removed, as shown in FIGS. 2 and 3, in this method, the injection rod 8 provided with an ultrahigh pressure water injection port 8a at the tip is provided around the existing pile 1 to be removed. The polygonal edge cutting surface 9 is inserted so as to surround the entire circumference of the existing pile 1 by sequentially repeating the process of cutting the ground into a panel shape by injection of ultra-high pressure water in the intrusion process or the pulling-up process. After forming 9..., The existing pile 1 is pulled out and removed.
[0023]
Specifically, in order to form the edge cut surface 9 that cuts off the peripheral frictional force between the existing pile 1 and the ground, three or more guide holes 7 are provided on the outer periphery of the existing pile 1 as shown in FIGS. The section from one guide hole 7 to the adjacent guide hole 7 is cut into a panel shape by jetting ultrahigh pressure water, and the edge cut surfaces 9, 9... Are formed in a polygonal shape so as to surround the existing pile 1 To. 4 is an example in which three guide holes 7 are provided and the edge cut surfaces 9, 9... Are formed in a triangular shape, and FIG. 5 is an example in which four guide holes 7 are provided and the edge cut surfaces 9 are formed in a square shape. , 9... Of course, you may make it form the edge cut surface 9,9 ... continuous in the polygonal shape more than a pentagon.
[0024]
As the injection rod 8, an injection rod used in the JSG method or the column jet grouting method can be used as it is, among the high-pressure injection stirring and mixing methods, which is a kind of ground improvement method. The former JSG method uses a double tube injection rod 8A shown in FIG. 10 (A), and at the same time as cutting the ground by spraying an ultra-high pressure hardened material liquid accompanied by air while rotating it into the ground. It is a ground improvement method for creating a solid body, and the latter column jet grouting method uses a triple pipe 8B shown in FIG. 10 (B) and rotates ultra-high pressure water with air into the ground. It is a construction method in which a ground is artificially created by spraying the ground and discharging the slime to the ground surface, and a solidified body of a cylindrical body is formed by simultaneously filling a hardening material therein. Note that the air is accompanied in order to increase the cutting distance. When the cutting distance is short, only the ultra-high pressure water may be injected without accompanying the air. In this case, a single tube is sufficient.
[0025]
In this example, the guide hole 7 is separately formed by boring prior to the insertion of the injection rod 8, but the injection rod used in the JSG method or the column jet grouting method is shown in FIG. As shown in Fig. 2, there is also a rod having a structure having a cutting bit at the tip of the rod. In this case, after penetration into the ground, a ground improvement body is created in the lifting process. Therefore, according to this, after cutting the ground with the injection rod 8, the edge cut surface 9 may be formed in the pulling process. The cutting site is filled with bentonite mud water to prevent the hole wall from collapsing.
[0026]
In addition, since there is no restriction on the sky outside, the injection rod 8 assembled to the required length can be suspended with a crane or the like and built in the guide hole 7. Underpinning, however, the construction is performed under low head conditions. For this reason, the unit rods having a length of 50 to 100 cm are successively added while being penetrated into the ground, and the unit rods are successively separated even when being pulled up.
[0027]
In order to reduce the number of the guide holes 7 and the number of penetrations of the injection rod 8 in forming the edge cut surface 9 surrounding the existing pile 1, as shown in FIGS. 6 and 7, the penetration point of the injection rod 8 is used. 2 or more on the outer periphery of the existing pile, and between the rod penetration points, the edge cutting surface 9 formed by super high pressure water injection from one rod penetration point and the edge cutting formed by ultra high pressure water injection from the other rod penetration point You may make it cut in a panel shape by making the surface 9 cross or make it continuous. 6 shows an example in which the edge cut surfaces 9, 9... Are formed in a square shape with two rod penetration points, and FIG. 7 shows the hexagonal edge cut surfaces 9, 9,. It is an example. Of course, you may make it form the edge cut surface 9,9 ... in more polygonal shape than this.
[0028]
When the edge cut between the existing pile 1 and the ground is attempted according to the above procedure, as shown in FIG. 8, the removal is performed while alternately repeating the pulling of the existing pile 1 and the cutting of the lifted portion. As shown in the figure, the lifting is performed by placing lifting means such as hydraulic jacks 10, 10 around the existing pile, and providing beams 11 penetrating the existing pile 1. Are lifted upward by the hydraulic jacks 10 and 10 respectively, and when the existing pile 1 is pulled up by a predetermined length, the existing pile 1 is suspended by the hoist cranes 12 and 12 and the hydraulic jacks 10 and 10 are contracted. Then, a beam 11B penetrating the existing pile 1 is provided and supported so that the existing pile 1 does not fall after cutting. Then, in this state, the upper part of the existing pile 1 is cut with a wire saw, and the cut existing pile lump 1 </ b> A is moved in the lateral direction by the hoist crane 12. The existing pile 1 is removed by repeating this procedure sequentially. In addition, the hollow portion of the pile drawing is filled with poor blended mortar such as fluidized soil. Filling is done by pulling out the pile and filling the filler by the volume that was pulled out, but it takes a long time to separate and remove the pulled-out pile in small divisions. If it hardens at the bottom end and hinders pulling out, inject muddy water that does not adhere to the bottom end of the pile, and then fill it with poorly mixed mortar filler, such as fluidized soil, while pulling out the pile. There is also a method of filling. Furthermore, there is also a method in which muddy water is injected during pile removal to stabilize the natural ground, and after the extraction is completed, the filler is driven in water.
[0029]
(Other examples)
(1) In the above example, the existing pile 1 is a cast-in-place pile, but the pile type such as PC pile, RC pile, steel pipe pile, and joint pile is not limited.
[0030]
(2) Although the existing pile was made into the single pile, as FIG. 9 shows, the continuous pile like a steel pipe sheet pile etc. may be sufficient. In this case, the edge cut surface 9 cannot be formed so as to completely surround each steel pipe sheet pile, but it is possible to edge most of the circumferential frictional force.
[0031]
(3) The above example is an example of construction in a low head space with underpinning, but the present invention can also be applied when there is no upper limit. In this case, the injection rod can be built at once in an assembled state, and the existing pile can be pulled out and removed at once.
[0032]
【The invention's effect】
As described in detail above, according to the present invention, when removing an existing pile, even in a narrow place or a low head space, the circumferential surface between the existing pile and the natural ground is surely obtained by mechanized construction using a small device. The frictional force can be cut and the pile can be removed efficiently.
[Brief description of the drawings]
FIG. 1 is a construction procedure diagram of underpinning.
FIG. 2 is an overall view showing a procedure for removing a pile according to the present invention.
FIG. 3 is an enlarged view thereof.
FIG. 4 is a plan view showing an edge cutting procedure for an existing pile 1;
FIG. 5 is a plan view showing another edge cutting procedure for the existing pile 1;
FIG. 6 is a plan view showing another edge cutting procedure for the existing pile 1;
FIG. 7 is a plan view showing another edge cutting procedure for the existing pile 1;
FIG. 8 is a diagram showing a procedure for lifting and removing piles after edge cutting.
FIG. 9 is a plan view showing an example of edge cutting of a steel pipe sheet pile.
FIGS. 10A and 10B are enlarged sectional views of the tip portion showing an example of the structure of the injection rod 8;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Existing pile, 2 ... Building, 3 ... New pile, 4 ... Laying sand, 5 ... Replacement version, 7 ... Guide hole, 8 ... Injection rod, 9 ... Edge cutting surface

Claims (6)

Around the existing pile to be removed, an injection rod with an ultra-high pressure water injection port at the tip is inserted into the ground, and the ground is cut into a panel by injection of ultra-high pressure water during the penetration process or pulling process. A method for removing an existing pile, comprising forming a polygonal edge-cutting surface so as to surround the entire circumference of the existing pile or a large part of the existing pile by sequentially repeating the steps, and then pulling out and removing the existing pile. The penetration point of the said injection rod is set to 3 or more points on the outer periphery of the existing pile, and the section from one rod penetration point to the adjacent rod penetration point is cut into a panel shape by jetting ultrahigh pressure water. How to remove existing piles. Two or more penetration points of the injection rod are set on the outer periphery of the existing pile. Between the rod penetration points, an edge cut surface formed by super high pressure water injection from one rod penetration point, and ultra high pressure water from the other rod penetration point. The removal method of the existing pile of Claim 1 which cuts into a panel shape by making the edge cut surface formed by injection cross or continue. The method of removing an existing pile according to any one of claims 1 to 3, wherein the injection of the ultra-high pressure water is performed while accompanying compressed air around the periphery. The method for removing an existing pile according to any one of claims 1 to 4, wherein the spray rod uses a single pipe, a double pipe or a triple pipe. The removal method of the existing pile according to any one of claims 1 to 5, wherein the removal of the existing pile is performed while alternately repeating the pulling and the cutting for the pulling up.

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