JPH06207412A - Exiting pile removing method by mortar injection - Google Patents

Abstract

PURPOSE:To make it possible to remove a pile gradually with the rising speed of the pile matching the mortar injection speed by injecting mortar into a casing and pushing up a piston from the lower part of the piston, including the pile, by the amount of mortar injected cubic volume. CONSTITUTION:As accommodating an existing pile 1, a casing 4 is pounded to break off the contact between the pile 1 and the circumferential soil, compressed air is sent to the lower part of the pile 1 from the ground, the pile 1 is pushed up from its bottom and removed. In this case, force fed mortar is injected from a nozzle 6, which is provided on the lower part 11 of the pile 1, to the interior of the casing 4 through an injection pipe 5 attached to the casing 4. The pile 1 then rises in a piston shape together with a soil 20 above the mortar injected surface matching the mortar injection speed. As the pile 1 is lifted, the top of the pile 1 is supported and the casing 4 is removed, after which mortar is injected into the hollow made by the removal and simultaneously backfilling is carried out. Thus unexpected projection of the pile 1 is completely prevented and workability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method of removing existing foundation piles, etc., and particularly, by driving a casing into the surrounding ground and supplying compressed air to the lower side of the pile, the effect of plugging the soil in the casing is improved. The present invention relates to the improvement of a construction method for removing foundation piles, which are used to push up and remove piles that are cut off from the ground together with surrounding soil.

[0002]

2. Description of the Related Art In the dismantling work of ordinary buildings, after dismantling structures on the ground, the foundation is dismantled and removed, and finally the foundation piles are also removed, and new foundation work is carried out. . However, the piles are installed from the ground so that they do not disturb the current condition of the ground as much as possible, and even when removing the piles, there is no way to dig up to the tip of the piles, and pull out from the ground as much as possible. Desirable, but
This requires a force commensurate with the bearing capacity of the pile that has been stably held since construction, and the equipment used for that purpose has become large-scale, and various removal methods have been proposed. Among these methods, in the prior art, first, it is possible to release the supporting force due to the adhesion between the surrounding ground and the outer peripheral surface of the pile and the friction, and the mainstream is the vibrating pile driving machine. It has been developed as a method of using the machine on the pulling side.

On the other hand, the applicant's earlier proposal (Japanese Patent Application No. 53-
41655, title of invention “pile removal method by air”)
Then, as shown in FIG. 7, after the existing foundation is dismantled, the casing 4 is driven into the ground 2 on the outer periphery of the pile 1 by using the vibrating pile driver 3, and the pile 1 is taken into the casing 4. The pile 1 and the surrounding ground 2 are cut off over the entire length of the pile 1. The length of the casing 4 is determined by determining the length of the existing pile based on the survey data of the ground 2 for new construction, the old design data of the existing building, etc. A nozzle 6 is formed at the lower end toward the inside of the casing 4, and is connected to a compressed air supply source such as an air compressor 7 at the upper part, and the lower part of the pile 1 inside the casing 4 is attached. Compressed air is pressed into 11, and the pile itself and the soil 20 still attached to the surroundings are made to act as a piston in the casing 4, and the piston is raised by the volume increase due to the injected compressed air, and the pull-out force is increased. Instead, it discloses a method of removing the pile by utilizing the push-up force, and in particular, there is an advantage of preventing the pile from being damaged and becoming inoperable.

[0004]

The pile removing method using compressed air as described above has been proposed from a completely new viewpoint, but has the following problems. The nature of the soil is involved in the construction management of compressed air in the soil, and if there is a lot of air leaks along the casing, it is especially difficult to adjust the pressure and amount, and if control is lost, the action of the piston deviates from the casing. There was a risk of popping out the stake at an unexpected time. It is difficult to maintain the working state, and it is unstable and difficult to support with unfixed air when supporting the pile to prevent the pile from falling during the work by hanging the wire on the pushed piston. In general, it is difficult to prevent compressed air from leaking, and if there is an escape path for air, not only is loss high, but an eccentric load is generated during injection, which makes it difficult for the soil piston to operate. In addition, there is a disadvantage that mud mixed with groundwater is scattered and the workplace is polluted.

[0005]

SUMMARY OF THE INVENTION The present invention has been completed in view of the above problems, and a steel pipe casing is struck so as to accommodate an existing pile to separate the pile and the surrounding ground. In the method of cutting the edge and removing the pile by work from the ground, a step of injecting mortar from a nozzle provided at the lower end of the casing toward the lower end of the pile in the casing, a step of raising the pile by injecting mortar The method is characterized by including a step of removing the pile while supporting the upper end of the pile as it rises, and a step of removing the casing before hardening of the mortar.

Therefore, according to the present invention, the mortar is first injected into the casing to form the piston including the target pile, and the piston is pushed up from below the piston by the injection volume. Can be applied to the entire cross section of the casing without the need for large mechanical withdrawal forces and thus it is easy to tie the lift to the top of the pile during final withdrawal. In addition, not only does compressed air not cause large leaks or large volumes like compressed air, but it can be performed on all cross sections by mortar that is injected after forming a cavity. The objective of providing a slow speed removal method commensurate with speed is achieved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described with reference to the drawings showing an embodiment. 1 is a cross-sectional view illustrating a concrete pile adopting the removal method of the present invention, FIG. 2 is a plan view corresponding to FIG. 1, and reference numerals in FIG. 7 are common to corresponding members. . First, in FIGS.
Is an existing pile existing in the ground 2 on the outer periphery, and the casing 4 is driven into the pile 1 by using the vibrating pile driver 3. The diameter of the casing 4 is determined in accordance with the type of the existing pile 1 (wood pile, concrete pile, etc.) and the thickness and the nature of the soil 20 taken into the pile 4, but does not require a strict dimension. The pile 1 and the soil 20 and the surrounding ground 2 are cut along the outer surface of the casing 4 over the entire length of the pile 1 as in the prior art. An injection pipe 5 is attached to the casing 4 in the vertical direction in advance, and a nozzle 6 is formed and fixed toward the center of the casing 4 at the lower end, and an air compression as a supply source of compressed air is provided above. By connecting to the machine 7, compressed air can be pressed into the lower part 11 of the pile.

Since the injection pipe 5 projects outwardly of the casing 4 in the ground, in order to firmly fix the injection pipe 5 along the generatrix of the casing 4, the strip strips in the circumferential direction are vertically spaced at appropriate intervals. 51 is used to form and fix a slope on the outer surface of the strip 51. A double wall steel pipe having a partition may be used. Further, in the present invention, in the above-ground piping of the injection pipe 5, the three-way valve 52 is provided, the mortar transport pipe 53 is connected so that the three-way valve 52 joins, and the other end is connected to the grout pump 54. Compressed air and mortar can be alternately switched and supplied to the injection pipe 5 via a three-way valve 52. Numeral 55 is a mud making plant for preparing mortar, and mortar may be a poorly mixed mortar as long as the fluidity is not impaired.

[0009]

[Operation] The operation of the existing pile removing method of the present invention will be described with reference to the steps shown in FIGS. The dismantling of the conventional building is the same as the conventional technique until the foundation is removed, and when the pile 1 is confirmed, the casing 4 is driven around it.
The casing 4 can be driven by using the vibrating pile driver 3 as in the conventional technique. However, in the present invention, the nozzle 6 of the injection pipe 5 is located near the lower end of the pile 1 and the pile 1 is driven. Try to hug and accommodate. After the step of driving the casing 4, as shown in FIG. 3, compressed air is sent from the air compressor 7 to the injection pipe 5, compressed air is blown into the casing 4 from the nozzle 6, and the pile 1 is put into the soil 20. The perforations 21 are formed so as to reach the center position of the.

Then, the casing 4 is swung around the pile 1 by the swivel device 40 provided on the outer periphery of the upper portion of the casing 4. The swivel device 40 is configured as a means for applying an external force in the horizontal tangential direction of the head 12 of the pile 1, and in FIGS. 3 and 4, a pinion 42 supported from the ground surface is engaged with a headband-shaped annular rack 41. Then, the pinion 42 is driven and operated by an appropriate drive device 43 to horizontally rotate the casing 4. Therefore, the nozzle 6 is sequentially swung to horizontally expand the perforations 21 in a fan shape,
A cutting plane 22 of the air layer is formed in the plane of the pile 1 at this height. It is not necessary to remove the cut soil 20. The swivel device 40 for horizontally swiveling the casing 4 is not limited to the above. For example, a hydraulic cylinder is used as a drive device, a pinion is provided at the tip of the ram, and the rack 41 is engaged with the rack 41 by expansion and contraction of the cylinder. You may turn together. If a horizontal arm is provided on the head of the casing 4 and a hydraulic cylinder is attached to the tip of the horizontal arm, the casing 4 can be swung by its expansion and contraction.

Here, as shown in FIG. 5, if the three-way valve 52 is switched to connect the mortar transport pipe 53 to the injection pipe 5, and the mortar is pressure-fed from the grout pump 54 to the injection pipe 5, the mortar can be easily nozzled. It is grouting while filling the inside of the cavity perforated with 6, mortar is spread all over the permeated portion of the compressed air, and it is pressed into the cutting surface 22 in the form of a disk. Therefore, above the cutting surface 22, an operating body is formed in which the casing 4 is a cylinder and the pile 1 with the soil 20 attached therein is a piston-like lump, and the subsequent press-fitting of the mortar is the bottom surface of the piston. And the inside of the casing 4 is raised to grow by the amount of the mortar 8 injected, and the pile 1 is slowly moved upward.

Then, when the upper part 12 of the pile 1 which has been pushed up reaches a height which is 1 to 1.5 m higher than the top of the casing 4, the biston part including the pile 1 is supported by the mortar 8 and the pile 1 is kept. The wire rope 30 is attached to the upper portion 12, and is suspended and supported by an appropriate lifting device, and the mortar 8
Using the vibration of the vibrating pile driver 3 etc., the pile 1
Pull out. At the end of the process, as shown in FIG. 6, the chuck positions of the casing 4 and the vibrating pile driver 3 are changed.
If the casing 4 is pulled out and collected, the mortar 8 is backfilled to the filled state after the pile 1 including the driving position of the casing 4 is pulled out.

In the above process, the mortar spreads and closes all the slits penetrated by the compressed air, the injection pressure is converted into the upward movement of the piston, and the mortar does not undergo a rapid volume change. According to the removal method of the present invention, not only the injection of mortar into the casing 4 acts in the removal direction of the piles to improve efficiency, but also the removal work of the piles results in backfilling after removal, and also the removal of the casing. Since there is no time difference, it is possible to improve the method of removing the piles very efficiently. In the present invention, since the rise of the pile by mortar injection is the basic means for removing the pile, the supply of compressed air precedes and the formation of the perforations means direct perforation and permeation by the injection of mortar. It is easy and averaged. Therefore, connecting the air compressor 7 as a source of compressed air and installing the swivel device 40 does not limit the present invention, but represents a preferred embodiment.

[0014]

According to the method of removing an existing pile of the present invention, a casing of a steel pipe is laid so as to accommodate the existing pile, the pile is cut off from the surrounding ground, and the pile is removed by work from the ground. In the construction method, a step of injecting mortar from a nozzle provided at the lower end of the casing toward the lower end of the pile in the casing, a step of raising the pile by injecting mortar, while supporting the upper end of the pile as it rises. Since it is composed of the steps of removing the pile and removing the casing before hardening of the mortar, it overcomes the difficulty of controlling compressed air and completely prevents the pile from unexpectedly popping out. Not only is it possible to eliminate the problems of mud scattering and environmental pollution. Furthermore, since the equipment required to carry out the invention is only the addition of mortar injection equipment to the piping system, there is no increase in construction costs, and the use of mortar is rather directly linked to backfilling after removal. From this, a particular advantage can be expressed. When turning the casing,
By forming a round cut surface with compressed air from the nozzle, the injection pressure after switching to mortar acts on the entire cross section of the casing to obtain a uniform rising force from the bottom surface of the piston, and the mortar to be injected It is possible to provide a slow removal method commensurate with the injection rate of slag, and it provides a clear solution to the removal method of piles for soils with undefined properties. Moreover, it should be said that the present invention is an invention that can make a great contribution to the construction industry through the improvement of underground construction for effective use such as redevelopment of land.

[0015]

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a method for removing an existing pile of the present invention.

2 is a plan view of the embodiment of FIG. 1. FIG.

FIG. 3 is a cross-sectional view of a casing showing a compressed air press-fitting step of the present invention.

FIG. 4 is a plan view of a main part for explaining turning of a casing.

FIG. 5 is a cross-sectional view of a casing showing a mortar grouting process.

FIG. 6 is a vertical sectional view showing a final step of removing a pile.

FIG. 7 is a vertical cross-sectional view of a method of using compressed air among the conventional methods of removing existing piles.

[0016]

[Explanation of symbols]

 1 pile 2 ground 3 vibrating pile driver 4 casing 5 injection pipe 6 nozzle 7 air compressor 8 mortar 11 lower part of pile 12 upper part of pile 20 soil 21 drilling 22 cutting surface 30 wire rope 40 swivel device 41 ring rack 42 pinion 43 Drive device 51 Strip plate 52 Three-way valve 53 Mortar transport pipe 54 Grout pump 55 Mud plant

Claims (3)

[Claims] 1. A method of placing a steel pipe casing so as to accommodate an existing pile, cutting the pile from the surrounding ground, and removing the pile by work from the ground, the steel pipe casing is provided at the lower end of the casing. Step of injecting mortar from the nozzle toward the lower end of the pile in the casing, step of raising the pile by injecting mortar, step of removing the pile while supporting the upper end of the pile as it rises, before hardening of the mortar A method for removing an existing pile by mortar injection, which comprises a step of removing the casing. 2. An injection pipe reaching the nozzle is attached to the casing, and the upper end side is switchably connected to a source for supplying compressed air and a pump for feeding mortar under pressure. The method for removing an existing pile by pouring mortar according to claim 1, wherein perforations are formed inside by injection, and then mortar is injected. 3. The nozzle provided at the lower end of the casing is fixed toward the center of the casing, and by rotating the casing, a cavity for supplying compressed air is formed in the horizontal plane near the lower end of the pile. The method for removing an existing pile by pouring mortar according to claim 2, wherein a piston-like lump is formed in the casing by the soil and the pile above.