JPH11117288A - Ground improving method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently form a continuous wall and a lattice-like improvement section by forcefully thrusting a metal injection pipe into a pipe bender in a guide pipe, bending it, moving it forward into a circular arc shape, forcefully extracting it, and injecting a grout at a high pressure. SOLUTION: A guide pipe 2 is inserted and installed into a vertical shaft (a). A pipe bender 1 having a curved passage 4c is fixed to the guide pipe 2. A metal injection pipe 3 is thrust into the pipe bender 1 for bend machining in the lateral direction. The metal injection pipe 3 is advanced into a circular arc shape while boring water is injected at a high pressure from the tip of a double pipe. The metal injection pipe 3 is extracted after it is advanced into the circular arc shape, and a tip 3a is retreated to the outlet section 4b of the pipe bender 1. A grout is injected at a high pressure from an injection nozzle 3a1 to form a ground improvement section with a rectangular quadrilateral shape while the tip 3a is retreated. The process is repeated at each position while the guide pipe 2 is stepped up, thereby a columnar ground improvement section with a planar rectangular shape is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method, and more particularly to a ground improvement method and apparatus for improving a ground by high-pressure injection of grout.

[0002]

2. Description of the Related Art There are various types of so-called grouting methods for improving the ground by grouting, such as a single pipe injection method, a double pipe injection method and a jet grouting method (high pressure injection method). The jet grouting method in which grout is injected under high pressure while rotating in the ground can form a columnar ground improvement part. For example, by connecting the columnar improvement parts, a column-type continuous wall can be formed in the ground.

[0003]

The jet grouting method can form a columnar improvement in the ground, but since the cross section of the columnar improvement is circular, for example, when forming a column-type continuous wall, It was necessary to connect the parts while overlapping them, resulting in a connection loss due to the overlap, and the construction efficiency was not very good.

As a countermeasure for preventing liquefaction of the ground, it is advantageous from the viewpoint of construction to form a grid-like ground improvement part in the ground, but in the conventional jet grouting method, the improvement part becomes cylindrical and connection loss is reduced. Therefore, it was not suitable for such construction.

According to the present invention, it is possible to form a continuous wall or a grid-like improved portion in the ground without connection loss by applying the jet grouting method, and when the ground is entirely improved, the improvement range per work is improved. The purpose of the present invention is to provide a ground improvement method and an apparatus for expanding the ground.

[0006]

SUMMARY OF THE INVENTION The present invention provides a guide tube having a tube bender therein, and a metal injection tube which is subjected to a bending process from a longitudinal direction to a lateral direction by forcibly pushing the guide tube through the tube bender. This is a method of improving the ground by high-pressure injection of grout using the above, after the guide pipe is inserted and installed in the ground for improvement, forcibly push the metal injection pipe through the pipe bender inside the guide pipe, from the vertical direction While performing bending in the lateral direction, the tip of the injection pipe is moved forward in a substantially horizontal arc shape through the pipe bender and into the ground, and after the end of the forward movement, the injection pipe is forced upward. Withdrawing, the injection pipe tip is moved backward from the advance position into the pipe bender, and during at least one direction of this back and forth movement,
The ground improvement part is formed by injecting the grout outward at a high pressure through the injection port at the tip of the injection pipe,
The present invention relates to a soil improvement method characterized by repeatedly performing the formation operation of the soil improvement portion while stepping up the guide tube toward the ground.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method of the present invention will be described below with reference to the accompanying drawings.

When the method of the present invention is carried out, as shown in FIG. 1, a guide tube 2 in which a tube bender 1 is installed and fixed at an inner lower end portion, and the guide tube 2 is forcibly pushed through the tube bender 1 so as to be vertically oriented. And a metal injection pipe 3 which is subjected to bending in the lateral direction from the ground.

The tube bender 1 is provided with a bending passage 4 having an inner diameter substantially equal to the outer diameter of the metal injection tube 3, the inlet 4 a having a vertically upward opening, an outlet 4 b having an obliquely downward opening, and And a curved passage 4c communicating between them. The curved passage 4c is a portion that actually functions as a tube bender.

The metal injection tube 3 is divided into a tip 3a and a base 3b.

The tip portion 3a is a portion to be bent in an arc shape by forcible pushing through the tube bender 1. In order to withstand repeated bending, the end portion 3a is seamless in the pipe axis direction and the pipe surrounding direction. For example, a genuine steel pipe, stainless steel pipe, copper pipe (including a copper alloy) or the like manufactured by cold drawing can be suitably used. The length of the tip 3a is not particularly limited and may be appropriately selected and determined depending on construction conditions and the like.
Usually, it is selected from a range of about 50 to 600 cm.

On the other hand, the base portion 3b is a portion which is not subjected to bending processing, and for example, a fixed length tube 3b1 made of steel may be used by successively adding.

An injection port 5 is formed on each side of the distal end of the tip 3a of the metal injection tube 3.

FIGS. 2 (a) to 2 (d) show a situation in which the method of the present invention is implemented by applying the ground improvement apparatus shown in FIG.

FIG. 2A shows a process of excavating a shaft a on the ground A to be improved. For excavating the shaft, for example, casing excavation is applied. In the figure, b denotes a casing.

FIG. 2B shows a state in which the guide tube 2 is inserted and installed in the shaft a after the casing b is extracted.
, A regular-size general portion 2a is sequentially added. still,
The insertion and installation of the guide tube 2 into the improved target ground A may be performed while directly piercing by applying a piercing means provided in the guide tube 2 without the casing digging step.

FIG. 2C shows the state of the step of inserting the metal injection pipe 3 into the ground. The tip 3a of the metal injection tube 3 is pushed into the tube bender 1 by applying a forced pushing means such as a hydraulic jack.
The front end 3a is bent from the vertical to the horizontal while passing through the curved passage 4c, and the horizontal part 3a1 advances into the ground through the shaft a to protrude and advance in the horizontal arc in the ground. go.
In addition, if the metal injection pipe 3 is formed as a double pipe (not shown) and the drilling water can be injected at a high pressure from the tip of the injection pipe, the arc can be formed without any trouble even on a hard ground. Can be propelled.

The effective horizontal movement distance by arc propulsion varies depending on the curvature of the curved passage 4c of the machining passage 4, but is usually about 40 to 60% of the length of the tip 3a.

After the arc propulsion of the tip 3a of the metal injection pipe 3 is completed, as shown in FIG. 2D, the metal injection pipe 3 is pulled out to the ground by applying a forced withdrawing means such as a hydraulic jack. The tip 3a is moved backward to a position near the outlet 4b of the processing passage 4 of the pipe bender 1.

During the backward movement of the injection pipe tip 3a, a high pressure (for example, 200 kg / c) is applied from the ground through the injection pipe 3.
The grout sent at m ² ) is injected from the injection ports 3a1 (see FIG. 1) on both sides of the tip of the tip 3a. This high-pressure injection forms a ground improvement portion B having a right-angled quadrilateral shape as schematically shown in FIG. The length x of one side of the ground improvement portion B corresponds to twice the effective injection distance x1 of the high-pressure injection,
The length y of the other side corresponds to the effective horizontal movement distance of the tip 3a.

By repeating such a ground improvement operation at each step-up position while stepping up the guide tube 2, it is possible to form a columnar ground improvement part having a plane quadrangle in the ground.

FIG. 4 shows a state in which the continuous wall B1 is formed by applying the method of the present invention. In the method of the present invention, since the rectangular improved portion can be formed, the continuous wall B1 can be formed without connection loss. In the case of a continuous wall, its thickness corresponds to the effective horizontal movement distance y of the tip 3a, and the effective horizontal movement distance y may be selected from a range of, for example, about 30 to 100 cm depending on the scale of the construction.

FIGS. 5A and 5B show the state of formation of the planar lattice-like improved portion B2. In this case, as shown in FIG. 5 (a), a cross-shaped improved part B21 is first formed, and as shown in FIG. Is obtained. In forming the cross-shaped improved portion B21, in each step,
The guide pipe 2 is turned by 180 °, and the ground improvement operation is performed at each turning position according to the method of the present invention. The effective moving distance y of the injection pipe tip 3a at the time of forming the grid-like improved portion may be, for example, about the same as that of a continuous wall.

FIG. 6 shows the state of improvement of the overall improvement section B3.
The effective moving distance y of the injection pipe tip 3a is a maximum length, for example, 30
About 0 cm is selected. The effective injection distance x of the grout is said to be about 150 cm at the maximum, depending on the construction conditions, so that a substantially square ground improvement part can be obtained.

As shown in FIG. 7, the ground improvement section B3 rotates the guide pipe 2 by 180 ° in each step, and performs the ground improvement operation in each rotation change position according to the method of the present invention, thereby improving the ground. The range can be doubled.

FIG. 8 shows a state in which a ground improvement part B4 is formed below an underground obstacle c such as a buried pipe. According to the method of the present invention, the injection pipe tip 3a is propelled in the lateral direction in the ground, so that even if there is such an obstacle, the improved portion B4 can be formed below the obstacle without any trouble.

In the present invention, the grout injection in each step may be performed at the time of forward movement instead of at the time of the aforementioned backward movement, or may be performed continuously during both forward and backward movements. You may.

Further, as is generally practiced in the high-pressure injection of grout, if the injection port 5 has a double structure and the grout is injected while injecting air from the surroundings, the grout can be effectively used. The injection distance can be extended.

As shown schematically in FIG. 9, if the two metal injection tubes 3, 3 are inserted into the ground through the guide tubes while being turned by 180 °, the guide tubes can be turned by 180 °. An enlarged ground improvement is obtained without the need for a displacement operation, as in the case shown in FIG.

[0030]

According to the present invention, a rectangular ground improvement portion can be formed, and it is possible to efficiently form a continuous wall or a grid-like improvement portion without connection loss. Furthermore, by selecting the maximum value as the moving distance of the injection pipe tip, an enlarged wide ground improvement area can be obtained, the number of constructions per unit area can be reduced, and the construction cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a single type pipe bender applied to the method of the present invention.

FIG. 2 is an explanatory view showing one embodiment of the method of the present invention in the order of steps.

FIG. 3 is a plan view of a ground improvement part formed by the method of the present invention.

FIG. 4 is a plan view showing a state where a continuous wall is formed from a ground improvement part.

FIG. 5 is a plan view showing a state in which a grid-like ground improvement part is formed, including a cross improvement part as a constituent element.

FIG. 6 is a plan view showing a formation state of a ground improvement part when a maximum value is selected as an effective movement distance of an injection pipe tip.

FIG. 7 is a plan view showing a state of ground improvement when the ground improvement is performed by rotating the guide tube by 180 ° in each step.

FIG. 8 is an explanatory diagram showing a situation in which a ground improvement part is formed below an underground obstacle such as a buried pipe.

FIG. 9 is an explanatory view schematically showing an implementation state of the method of the present invention when two metal injection tubes are used while changing the direction by 180 °.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipe bender 2 Guide pipe 2a General part 3 Metal injection pipe 3a Tip 3a1 Sideways part 3b Base 4 Bending path 4a Entrance part 4b Exit part 4c Curved passage 5 Injection port

Claims (7)

[Claims] 1. A high-pressure grout injection using a guide tube having a tube bender therein and a metal injection tube subjected to bending from a vertical direction to a horizontal direction by forcibly pushing the guide tube through the tube bender. A method of improving the ground,
After the guide pipe is inserted and installed in the ground to be improved, the metal pipe is forcibly pushed through a pipe bender inside the guide pipe to bend the pipe from the vertical direction to the horizontal direction while bending the metal pipe. After moving forward in a substantially arcuate shape in the horizontal direction through the pipe bender and into the ground, after the forward movement is completed, the tip of the injection pipe is moved backward from the advanced position into the pipe bender as the injection pipe is forcibly pulled upward. During at least one direction of the back and forth movement, a ground improvement part is formed by injecting grout outward at a high pressure through an injection port at the tip of the injection pipe, and thereafter, a guide pipe is placed on the ground. A ground improvement method characterized by repeatedly performing the above-described operation of forming the ground improvement portion while stepping up. 2. A metal injection pipe is provided with injection ports on both the left and right sides of the tip of the tip, and grout is injected with high pressure through the injection ports on both the left and right sides, so that the left and right sides of the metal injection pipe are moved with reference to the movement trajectory of the injection pipe tip. The ground improvement method according to claim 1, wherein ground improvement portions are formed on both sides. 3. In each step position, the guide tube is turned by 180 ° in a direction around its central axis, and the formation operation of the ground improvement portion is performed at each of the changed positions. The ground improvement method according to claim 1 or 2. 4. At each step position, two metal injection pipes are inserted into the ground to be improved at an angle of 180 °, and an operation of forming a ground improvement portion is performed through these two metal injection pipes. The ground improvement method according to claim 1 or 2, wherein: 5. The soil improvement method according to claim 1, wherein drilling water is sprayed forward from the tip of the metal injection pipe when the metal injection pipe advances underground. 6. A guide tube provided with a tube bender therein, and a metal injection tube subjected to bending from a vertical direction to a lateral direction by forcibly pushing the guide tube through the tube bender, and the guide tube and the inside thereof. The pipe bender can be penetrated into the ground where the purpose is improved, and the tip of the metal injection pipe is bent through the pipe bender from the vertical direction to the horizontal direction, which is received by forcibly pushing the pipe bender in the guide pipe. The metal injection tube can be moved forward in a substantially arcuate direction, and the metal injection tube can be forcibly pulled upward so that the metal injection tube can be moved backward from the advanced position to the inside of the tube bender. The injection port for injecting the grout sent from the ground at high pressure into the ground during the movement to the ground is provided on at least one of the left and right sides of the tip of the injection pipe. Board improvement equipment. 7. The ground improvement apparatus according to claim 6, wherein the metal injection pipe is configured to be capable of injecting drilling water from the tip.