JPH111919A - Method and equipment for preventing liquefaction of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an equipment for preventing liquefaction of ground which does not require cutting water nor air for drilling the ground and by which even sandy ground can be protected from liquefaction. SOLUTION: A crown bit 20 having a wire line head is set at the inside of the front end of a hollow rod auger 10. An overshot connected to a rope 2a is inserted and fixed to the wire line head after the ground has been drilled down to a specified depth and then the overshot is lifted together with the crown bit 20. And then a drain filter is inserted into the hollow rod auger 10 and the auger 10 is lifted in the state that the drain filter is left.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to liquids generated by earthquakes on artificially formed lands such as landfills or embankments, as well as on sandy soils with high groundwater levels and high groundwater levels on sea and riverside lands. The present invention relates to a soil liquefaction prevention method for preventing liquefaction and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a method for preventing liquefaction of a ground in which a drainage rod 40 shown in FIG. 4 is buried in a well hole 1 which is drilled at predetermined intervals in the ground. This drain rod 40
A filter material 42 is wound around the outer peripheral surface of a fibrous void structure 41 in which resin filaments are laminated in a hollow cylindrical shape in a curled state and the contact portions of the filaments are welded, and further corresponds to the stratum. Then, a non-water-passing portion 43 was formed in the filter material 42 of the drain rod 40. In the figure, 41a
Is a hollow hole of the filament void structure 41.

The well hole 1 is drilled using a double pipe, then the inner pipe is pulled up, and a drain rod 4 is inserted into the outer pipe.
After inserting 0, the draining rod 40 is left, and a construction method of pulling up only the outer tube has been used. However, in this case, since cutting water was necessary, it was necessary to treat the equipment for supplying the cutting water and the sludge from the wastewater, which required a cost for the equipment and treatment. In addition, when cutting water is used in a sandy ground, there is a danger that the ground may be affected around the ground.

Accordingly, as disclosed in the embodiment of Japanese Patent Application Laid-Open No. 6-65513, the use of a drilling device such as an auger is exemplified. The auger was pulled out while pushing the drain rod 40 into the water.

[0005]

However, when an auger is used, drilling can be performed without cutting water. However, in a structure in which a bit at the tip is opened, the bit is not structurally strong and an earth pressure acts upon opening. The operation was uncertain. Furthermore,
It was also necessary to apply air pressure to prevent earth and sand from entering the bit mating surface.

The present invention has been made in view of the above-mentioned circumstances, and is capable of drilling without requiring cutting water or air.
It is an object of the present invention to provide a method and a device for preventing liquefaction of a ground that can prevent liquefaction even on sandy ground.

[0007]

In order to achieve the above object, in the method for preventing liquefaction of ground according to the present invention, drainage filters are buried in the ground at predetermined intervals by the following steps. (1) A detachable Kronen bit is fitted into the tip of the hollow rod auger with its cutting surface protruding from the rod tip, and the hollow rod auger is rotated and fed by a ground drill, and A step of drilling a well hole of a predetermined diameter and a predetermined depth, (2) a step of detaching the kronenbint from the tip of the hollow rod auger, and (3) a hollow circle with the resin filament curled. The hollow rod auger is provided with a drain filter having a length substantially corresponding to the depth of a well hole, in which a filter material is wound around an outer peripheral surface of a filament void structure formed by laminating in a columnar shape and welding a contact portion between filaments. (4) a step of lifting the hollow rod to the ground.

The method for preventing liquefaction of the ground according to the present invention comprises:
A drain filter is buried in the ground at predetermined intervals by the following steps. (1) A kronen bit is fitted into the hollow of the distal end of the hollow rod auger with its cutting surface protruding from the rod distal end, and a latch is inserted into the concave end of the inner wall of the hollow rod auger at the base end of the kronen bit. Connecting the detachable wire line head, rotating and feeding the hollow rod auger by a drilling machine on the ground, and drilling a well hole having a predetermined diameter and a predetermined depth in the ground; (2) From the base end of the hollow rod auger, insert an overshot to which a rope is connected and engage with the spear at the base end of the wireline head, pull the rope to close the latch and form a recess in the inner wall of the hollow rod auger. Disengagement, the process of lifting the wireline head to the ground with the kronen bit,
(3) The depth of a substantially well hole in which a filter material is wound around the outer peripheral surface of a fibrous void structure obtained by laminating resin filaments in a curled state and laminating a contact portion between the filaments. A step of inserting a drain filter having a length corresponding to the length into the hollow hole of the hollow rod auger, and (4) a step of lifting the hollow rod auger to the ground.

Further, when the hollow rod auger is lifted, the hollow rod auger is rotated in the reverse direction, and the hollow rod auger is lifted while feeding the residual soil or the gravel material.

Further, in the step (4), a filler is filled in the gap between the drain filter and the well hole during and after the hollow rod auger is lifted.

[0011] In the step (3), the hollow hole of the drain filter has a large number of through-holes around its entire length, and a water-passing pipe having a predetermined gap between itself and the hollow hole. Is inserted.

In addition, a non-water-permeable portion is formed at a predetermined position in the middle of the drainage filter for a predetermined length corresponding to the formation.

[0013] The apparatus for preventing liquefaction of ground according to the present invention comprises:
A hollow rod auger having a hollow shaft center and a concave portion on an inner wall at a predetermined position near a tip, and a krone mounted so as to be able to be fitted and removed with a cutting surface protruding from the tip inside the hollow of the tip of the hollow rod auger. And a wire line head having a tip connected to the base end of the kronen bit and an overshot that engages and disengages with the head, and the resin filaments are laminated in a hollow cylindrical shape in a curled state. And a drain filter with a filter material wound around the outer peripheral surface.

In addition, a water passage pipe having a large number of through holes around the entire length thereof is inserted into the hollow hole of the drain filter with a predetermined gap between the water filter and the hollow hole.

Further, a non-water-permeable portion is formed at a predetermined position in the middle of the drainage filter in a predetermined length corresponding to the formation.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The method of the present invention is as shown in FIGS. That is, the drilling machine 2 is set at the driving position as shown in FIG. As shown in FIG. 2B, the hollow rod auger 10 is gripped by a drill head and rotated and fed, and as shown in FIG. 2C, a well hole 1 having a predetermined diameter and a predetermined depth is formed in the ground. . In this case, the earth and sand in the well hole 1 is discharged to the ground by the screw. Next, FIG.
As shown in FIG.
a (see FIG. 6) is inserted into the spear 31 at the base end of the wire line head 30 (FIG. 6) shown in FIG. 6) and pulling the rope 2a, the latch 32 is closed as shown above the center line in FIG. 6, and the recesses 11, 1 in the inner wall of the hollow rod auger 10.
1 (FIG. 6) is disengaged, and the wireline head 30 is lifted with the Kronen bit 20 to the ground.

Next, as shown in FIGS. 4 and 5, on the outer peripheral surface of the fiber void structure 41 in which the resin fibers are laminated in a hollow cylindrical shape in a curled state and the contact portions between the fibers are welded. As shown in FIG. 3 (e), the drain rod 40 as the drain filter having a length corresponding to the substantially well hole around which the filter material 42 is wound is inserted into the hollow hole of the hollow rod auger 10. In this case, a non-water-permeable portion 43 is formed at a predetermined position in the middle of the drainage rod 40 for a predetermined length corresponding to the stratum. This is because, when a poorly permeable layer is present in the middle of the ground, fine particles gradually dissolve out and adhere to the filter material 42, and are sequentially deposited in the filament void structure 41, thereby preventing clogging. It is to prevent it from getting up. Therefore, in the ground where there is no impervious layer,
3 is unnecessary.

Next, with the drain rod 40 remaining,
As shown in FIG. 3 (f), the auger 10 is pulled up to the ground while rotating in the reverse direction. In this case, the hollow rod auger 10
When the is lifted, the hole wall collapses and the periphery of the drainage rod 40 is filled, but sand 1a may be filled as a filler as shown by an arrow a in FIGS. 5 and 3f. . This is because, when the hollow rod auger 10 is pulled up while being reversed, if the sand as the filler 1a is put around the hollow rod auger 10, the hollow rod auger 10 is fed downward by a screw. In FIG. 5, 4
Reference numeral 1 denotes a filament void structure, reference numeral 42 denotes a filter material, reference numeral 1a denotes a filler such as medium-grained sand, and a two-dot chain line shows a position of the screw 12 pulled up, and a filler in a space where the hollow rod auger 10 is pulled up. 1a is filled. When the filling material 1a such as medium sand is filled, the stability of the formation by backfilling and the filter layer of the sand layer are constructed on the outer periphery of the drainage rod 40, and the life is improved by preventing the drainage rod 40 from being clogged. .

Further, a water passage pipe 44 having a predetermined gap between the hollow hole 41a and the hollow hole 41a may be inserted into the hollow hole 41a (FIG. 5) of the drain rod 40. This water pipe 4
Reference numeral 4 designates, for example, a plurality of through holes provided around the entire length of the PVC pipe, preventing buckling of the drain rod 40 at the time of insertion, inserting the hose into the water pipe 44 after the drain rod 40 is installed. Then, air is sent to the bottom portion while disturbing the surrounding soil water, and after reaching the bottom portion, the soil water in the drain rod 40 is sucked up. By doing so, when soil water is sucked up with a hose, fine grain sand that permeates through the filter material and precipitates at the bottom, and fine grain sand that adheres to the surface of the fiber can be simultaneously sucked up. By repeating this process several times, when backfill sand is filled, three stages of fine sand, fine sand that passes through the backfill sand layer, sand that assimilates into the sand layer, and sand that is larger than the sand layer that cannot pass. A filter with backfill sand that separates into sand can be constructed. The filter material wound around the filament void structure and the sand layer filter layer on the outer side of the drainage rod by the backfill sand filler can separate sand particles into two different stages.

However, the water pipe 44 need not be provided. In addition, a water pipe 44 is arranged to
After draining the soil water, the water pipe 44 may be removed. The drain rods 40 are buried in the ground at predetermined intervals by the steps described above.

Next, an apparatus for preventing liquefaction of the ground according to the present invention will be described. As shown in FIG. 6 (a), the hollow rod auger 10 has a hollow center and a concave portion 11 on an inner wall at a predetermined position near the tip. In the hollow portion of the distal end of the hollow rod auger 10, a kronen bit 20 is mounted so as to be able to be fitted and removed with the cutting surface 21 protruding from the distal end. FIG.
(B) shows the front, and shows the cut surface 21 of the Kronen bit 20. And this Kronen bit 20
The wireline head 30 is connected to the base end of the wire, and an overshot (not shown) is engaged with the spear 31 at the base end. The upper half from the center line in FIG. 6A is pulled in a state engaged with the overshot, the latch 32 is closed, and the concave portion 11 of the inner wall of the hollow rod auger 10 is formed.
The lower half shows a state in which the latch 32 is engaged with the recessed portion 11, and drilling is performed in this state.

Reference numeral 33 denotes a coil spring.
a to resiliently urge the wireline head 30 toward the distal end thereof,
In this case, the latch 32 is opened around the pivot pin 32b, and engages with the concave portion 11. When the spear 31 is pulled by the overshot, the coil spring 33 is compressed as shown in the upper half of FIG. 6A, the movable pin 32a moves to the position c along the long hole 32c, and the latch 32 It is closed around the pivot pin 32b and detaches from the concave portion 11. Figure (c) is a view of A- in Figure (a).
It is an A line cross section.

A drain rod 40 as a drain filter
As shown in FIG. 4 and FIG. 5, the fiber gap structure 41 and the filter material 42 constitute the fiber gap structure 41.
Is a resin fiber, that is, a resin such as a fiber polypropylene of about 2 mm is heated and melted, extruded from a nozzle, sequentially laminated in a curled state, and the contact points of the fibers are welded,
It is molded into a hollow cylindrical shape. On the outer peripheral surface, for example, a nonwoven fabric filter material 42 of polypropylene long fiber is wound. In addition, a non-water-passing portion 43 (FIG. 4) is formed between a predetermined length and a predetermined position in the middle of the drain rod 40 corresponding to the stratum. This non-water passing part 4
3 winds a vinyl tape etc., for example.

Whether the connection of the drain rod 40 is made by an adhesive,
Leaving a hollow hole 41a and fitting into the hollow hole 41a,
Alternatively, it can be connected to a joint using the outer periphery of the end of the drainage rod 40 by an adhesive, but if the depth of the well hole 1 is small, it is preferable to use only one.

The lower end of the drainage rod 40 is made of, for example, concrete, metal, or the like.
By embedding the end of the hole 0 in the concrete, the weight 45 shown in FIGS. 4 and 3 (f) can be attached to prevent floating from the well hole 1.

Further, as shown in FIG.
In the hollow hole 41a, a water-permeable pipe 44 such as a PVC pipe having a large number of through-holes around the entire length and having a dimension to maintain a predetermined gap between the hollow hole 41a and the hollow hole 41a may be inserted.

[0027]

According to the present invention described in detail above, the following effects can be obtained. (1) Since water can penetrate from almost the entire surface of the drain filter and there are hollow holes over the entire length, clogging does not occur even for a long time, and the liquefaction phenomenon of the ground can be almost semi-permanently prevented.

(2) Kronen bit which can be attached to and detached from the hollow rod auger and whose tip can be hermetically sealed is dry-processed using a kronen bit and a wire line head, so the equipment is simple and there is concern about pollution caused by cutting water. And the ground is not affected by cutting water.

(3) In the structure in which the water passage pipe is inserted into the hollow hole of the drain filter, fine sand or the like that has entered the hollow hole can be removed, so that the drain rod is further prevented from being clogged.
The life of the drain filter is further improved.

[Brief description of the drawings]

FIG. 1 is a first diagram showing the steps of the method of the present invention.

FIG. 2 is a second diagram showing the steps of the method of the present invention.

FIG. 3 is a third diagram showing the steps of the method of the present invention.

FIG. 4 is a longitudinal sectional view showing a state in which a drain rod as a drain filter is laid on the ground according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of a drain rod as a drain filter, showing one embodiment of the present invention.

FIG. 6 is a view of a hollow auger rod, a kronen bit and a wire line head mounted on the hollow auger rod, showing one embodiment of the present invention, wherein (a) is a longitudinal section, (b) is a front view, (C) shows a cross section taken along line AA of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Well hole 1a Filler 2 Drilling machine 2a Rope 10 Hollow rod auger 11 Depression 20 Kronen bit 21 Cutting surface 30 Wire line head 31 Spear 32 Latch 40 Drain rod as drain filter 41 Filament void structure 41a Hollow hole 42 Filter material 43 Non-water passing part 44 Water passing pipe

Claims (9)

[Claims] 1. A method for preventing liquefaction of a ground, wherein a drainage filter is buried in the ground at predetermined intervals by the following steps. (1) A detachable Kronen bit is fitted into the tip of the hollow rod auger with its cutting surface protruding from the rod tip, and the hollow rod auger is rotated and fed by a ground drill, and A step of drilling a well hole of a predetermined diameter and a predetermined depth, (2) a step of detaching the kronenbint from the tip of the hollow rod auger, and (3) a hollow circle with the resin filament curled. The hollow rod auger is provided with a drain filter having a length substantially corresponding to the depth of a well hole, in which a filter material is wound around an outer peripheral surface of a filament void structure formed by laminating in a columnar shape and welding a contact portion between filaments. (4) a step of lifting the hollow rod to the ground. 2. A method for preventing liquefaction of the ground, wherein drainage rods are buried in the ground at predetermined intervals by the following steps. (1) A kronen bit is fitted into the hollow of the distal end of the hollow rod auger with its cutting surface protruding from the rod distal end, and a latch is inserted into the concave end of the inner wall of the hollow rod auger at the base end of the kronen bit. A hollow wire auger is connected to the ground, and the hollow rod auger is rotated and fed by a ground drill to drill a well hole having a predetermined diameter and a predetermined depth in the ground; From the base end of the hollow rod auger, insert an overshot to which a rope is connected and engage with the spear at the base end of the wireline head, pull the rope to close the latch and form a recess in the inner wall of the hollow rod auger. The wire line head is lifted to the ground together with the krone bit, (3) the resin filaments are laminated in a hollow cylindrical shape in a curled state, and the filaments are brought into contact with each other. Inserting a drain filter having a length substantially corresponding to the depth of the well hole, into which the filter material is wound around the outer peripheral surface of the filament void structure having the welded portions, into the hollow hole of the hollow rod auger; And e) lifting the hollow rod auger to the ground. 3. The hollow rod auger is reversely rotated when the hollow rod auger is lifted, and the hollow rod auger is lifted while feeding remaining soil or gravel material. Liquefaction Prevention Law of the Earth. 4. The ground according to claim 1, wherein in the step (4), a filler is filled in a gap between the drain filter and the well hole during and after the hollow rod auger is lifted. Liquefaction prevention method. 5. In the step (3), the drainage filter has a plurality of through-holes around the entire length inside the hollow hole of the drainage filter, and a predetermined gap is maintained between the hollow hole and the water-permeable pipe. The method for preventing liquefaction of the ground according to claim 1 or 2, wherein a ground is inserted. 6. A non-water-permeable portion is formed at a predetermined position in the middle of the drainage filter in a predetermined length corresponding to a stratum, wherein the non-water-permeable portion is formed. 5. The method for preventing liquefaction of the ground according to 5. 7. A hollow rod auger having a hollow shaft center and having a concave portion on an inner wall at a predetermined position near a tip, and a hollow rod auger capable of fitting and removing with a cutting surface protruding from the tip inside the hollow at the tip of the hollow rod auger. The attached Kronen bit, the wire line head with the tip connected to the base end of this Kronen bit and the overshot that engages and disengages with this, and the resin filaments are laminated in a hollow cylindrical shape in a curled state. An apparatus for preventing liquefaction of the ground, comprising: a drainage filter in which a contact portion between filaments is welded and a filter material is wound around an outer peripheral surface. 8. A water pipe having a large number of through holes around the entire length thereof is inserted into the hollow hole of the drain filter with a predetermined gap between the water filter and the hollow hole. The liquefaction prevention device for ground according to claim 7, characterized in that: 9. The liquefaction of the ground according to claim 7, wherein a non-water-permeable portion is formed at a predetermined position in the middle of the drainage filter corresponding to the formation and has a predetermined length. Prevention device.