JPH08326049A - Driving method of drain material - Google Patents

Abstract

PURPOSE: To prevent the simultaneous lifting of a drain material when the drain material is penetrated into a sandy ground, etc., for obviating liquefaction by using a mandrel and the mandrel is extracted. CONSTITUTION: A drain material 2, in which an anchor 3 is fitted at a lower end, is inserted into a mandrel 1, and the mandrel 1 is penetrated into the ground while ejecting a water jet J from the lower end of the mandrel 1. The inserting section of the drain material 2 in the mandrel 1 is filled with water, and only the mandrel 1 is extracted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly intended to prevent liquefaction of sandy ground and the like, and when the drain material is cast on the ground by a mandrel, the drain material rises up at the same time when the mandrel is pulled out. The present invention relates to a method for placing a drain material that can prevent such a situation.

[0002]

2. Description of the Related Art When water is saturated in sandy ground and subjected to repeated shearing forces due to earthquakes in a low degree of tightness, the pressure of pore water existing between particles of earth and sand suddenly increases. As a result, the sandy ground loses shear strength, and a state in which it behaves like a liquid occurs, which is called a liquefaction phenomenon of the sandy ground.

If the ground is liquefied in this way, damage to the ground or damage to the structure, falling, unequal sinking, floating, etc. will occur. Therefore, the lower end of the drain material, which has a reinforcing member on the outer periphery and is made of a cylindrical filter having a mesh finer than the particles of the sand wound in a roll shape, is fixed to the anchor of the weight body attached to the lower end from inside the casing. Then, after the casing is penetrated to the specified depth position of the sandy ground, only the casing is pulled out, and the step of covering the upper end of the drained material cut for the specified length with the water-permeable cap is performed for the specified number of drained materials. The invention of Japanese Patent Publication No. 6-54003 relating to the method for preventing liquefaction is described.

However, in the above-mentioned conventional method, when the mandrel is pulled out, it is not possible to completely prevent the drain material from rising together with the casing, and it is necessary to re-drain the drain material that could not be installed at a predetermined position. There was a problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a mandrel was used to penetrate a drain material into sandy ground to prevent liquefaction. It is an object of the present invention to provide a method for placing a drain material that can prevent the drain material from rising and deforming together when the mandrel is pulled out later.

[0006]

In order to achieve the above object, a method of driving a drain material according to the present invention is such that a lower end of a mandrel is inserted into a mandrel with a cylindrical drain material having an anchor attached to a lower end thereof. It is characterized in that the mandrel is penetrated to a predetermined depth in the ground while jetting a water jet from it, and after filling the drain material insertion portion in the mandrel with water, only the mandrel is pulled out.

According to the above-mentioned method of the present invention, after the drain material has penetrated into the sandy ground or the like, the weight of the water filling the drain material in the mandrel at the insertion portion acts on the anchor attached to the lower end of the drain material. Thus, it is possible to prevent the drain material from rising together when the mandrel is pulled out.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a drain material placing operation to which the drain material placing method of the present invention is applied will be described below with reference to the drawings. FIG. 1 is a mandrel for drain material placing according to the first embodiment. 1 is a side sectional view of a lower part 11 of FIG. 1, and FIG.
A plan view in the A direction, FIG. 3 shows a lower part 11 of the mandrel 1 of FIG.
3 is a side cross-sectional view of the intermediate portion 12 connected to FIG.
FIG. 5 is a plan sectional view in the B direction, and FIG. 5 is a side sectional view of an upper portion 13 connected to the intermediate portion 12 of the mandrel 1 of FIG.

First, the lower portion 11 and the intermediate portion 1 shown in the above figures.
The drain material 2 to be inserted into the mandrel 1 including the upper portion 2 and the upper portion 13 is formed into a cylindrical shape with a mesh finer than the sand particles, and the outer periphery of the drain material 2 is the linear reinforcement body 2 of FIG.
It has one. A conical anchor 3 shown in FIGS. 1 and 2 is attached to the lower end of the drain member 2 inserted in the mandrel 1.

Next, the lower portion 11, the intermediate portion 12 and the upper portion 13 of the mandrel 1 have a double pipe structure, and the jet water J supplied from the jet water inlet 4 provided in the upper portion 13 is doubled. The jet water passage 5 formed as shown in FIGS. 1, 3, 4 and 5 of the pipe is flowed down, and a plurality of nozzles 6 arranged on the circumference of the lower end surface of the lower portion 11 are connected to the sand of the mandrel 1. Jet water J is spouted when penetrating into the ground.

In the upper part 13 of FIG. 5, reference numeral 7 indicates an insertion port for the drain material 2, and reference numeral 8 indicates the portion for inserting the drain material 2 in the mandrel 1 to be filled with water W. It is a water inlet. Next, a work procedure for placing the drain material 2 by using the double-pipe structure mandrel 1 of the first embodiment having the above-described configuration will be schematically described. First, as shown in FIG. After inserting the cylindrical drain material 2 into the inside, the anchor 3 is attached to the lower end of the drain material 2 without interfering with the nozzle 6 for jetting the water jet J of the mandrel 1, and the ground such as sandy ground is attached. Preparation for driving the drain material 2 to G is performed.

Therefore, as shown in FIG. 7, the anchor 3 is attached to the lower end.
With the tubular drain material 2 attached with the mandrel 1 inserted in the mandrel 1, the mandrel 1 is caused to penetrate into the ground G by the penetration by the press-fitting device while ejecting the water jet J from the nozzle 6 at the lower end of the mandrel 1. After the ground G is penetrated to a predetermined depth, the jetting of the water jet J from the nozzle 6 is stopped, and the water W is injected from the water inlet 8 into the portion of the mandrel 1 where the drain material 2 is inserted.

In this case, supply of water for the water jet J,
The water W can be supplied to the portion of the mandrel 1 where the drain material 2 is inserted by switching the valve operation. Next, as shown in FIG.
Only the mandrel 1 is pulled out upward, and the drain material 2 to which the anchor 3 is attached is left in the ground G, where the drain material 2 is cut to a predetermined length, and a water-permeable cap or the like is put on the upper end of the drain material 2. Measures are taken to prevent dirt and other substances from falling inside the drain material 2.

On the other hand, FIG. 10, FIG. 11, FIG. 12 and FIG.
FIG. 10 is a series of schematic views for explaining the working procedure of Example 2 in which the water jet pipe 9 is provided outside the mandrel 1 for placing the drain material 2 according to the method of the present invention, and FIG.
11, FIG. 11 shows a state corresponding to FIG. 7, FIG. 12 shows a state corresponding to FIG. 8, and FIG. 13 shows a state corresponding to FIG. 9, respectively, the same parts are denoted by the same reference numerals, and have the same operation, Detailed description thereof will be omitted.

[0015]

According to the method for driving a drain material of the present invention described above, the mandrel in which the drain material is inserted penetrates into the ground while ejecting a water jet from the lower end thereof. The action speeds up the penetration of the mandrel into the ground and reduces working time.

Further, after the mandrel has penetrated into the ground, the weight of the water acts on the anchor attached to the tip of the drain material by filling the water in the portion of the mandrel where the drain material is inserted, and when the mandrel is pulled out. Since it is possible to prevent the drain material from rising together, it is possible to satisfactorily drive the drain material. Further, the weight of the anchor attached to the lower end of the drain member can be made lighter than that of the conventional one, and the work efficiency can be increased and the work cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part showing a lower portion of a mandrel according to a first embodiment applied to a drain material placing operation by a drain material placing method of the present invention.

FIG. 2 is a plan view in the AA direction of FIG.

FIG. 3 is a side sectional view of an intermediate portion of the mandrel of FIG.

4 is a plan sectional view taken along line BB of FIG.

5 is a side sectional view of the upper portion of the mandrel of FIG.

FIG. 6 is a schematic explanatory view of a state in which a drain material is inserted in the double-tube mandrel shown in FIG.

FIG. 7 is a schematic explanatory view showing a state where the mandrel of FIG. 6 is penetrating into the ground.

FIG. 8 is a schematic explanatory diagram when the mandrel of FIG. 7 is penetrated to a predetermined depth of the ground.

FIG. 9 is a schematic explanatory diagram when only the mandrel of FIG. 8 is pulled out.

FIG. 10 is a schematic explanatory view of a state in which a drain material is inserted into the mandrel of Example 2 in which the water jet pipe is provided outside the mandrel applied to the method of the present invention.

11 is a schematic explanatory view of a state in which the mandrel of FIG. 10 is being penetrated into the ground.

FIG. 12 is a schematic explanatory diagram when the mandrel of FIG. 11 penetrates to a predetermined depth of the ground.

FIG. 13 is a schematic explanatory view when only the mandrel of FIG. 12 is pulled out.

[Explanation of symbols]

 1 Mandrel 2 Drain material 3 Anchor G Ground J Water jet W Water

Claims (1)

[Claims] 1. A cylindrical drain member having an anchor attached to the lower end thereof is inserted into the mandrel, and while the mandrel penetrates to a predetermined depth in the ground while jetting a water jet from the lower end of the mandrel, the mandrel A method of placing a drain material in which the drain material insertion part is filled with water and only the mandrel is pulled out.