JPH02104812A - Ground reinforcing drain pipe - Google Patents

Abstract

PURPOSE:To enable speedy work to be executed by arranging a plurality of drain slots on the pipe wall of a pipe. CONSTITUTION:A pipe 100 formed by providing a single pipe with a plurality of micropores 102 is vertically driven in poor subsoil 2, and an internal section is filled up with the sand 10 of good quality, gravels, a synthetic resin filter, or the like. Then, underground water is infiltrated through the micropores 102 as shown by arrow heads 6, and the pipe 100 is worked as a reinforcing member, by a peripheral frictional force as shown by arrow heads 104, a tip bearing force as shown by arrow heads 106, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reinforcing and improving the ground, and particularly to improving the reinforcement of the ground when constructing roads, structures, etc. on soft ground.

[Conventional technology]

There are two problems with soft ground:

■Low bearing capacity and causes ground failure.

■ Excessive subsidence or deformation may cause functional problems.

In order to solve these problems, various construction methods are being used to improve the volume change characteristics of soil, with the main focus being increasing the strength of the soil. The improvement principle and typical construction methods are shown below.

(1) Sand drain, paper drain method.

This product is intended for dewatering clay soil, and increases its strength and absorbs settlement through dewatering.

Used in conjunction with preload, well point, etc.

(2) Sand compaction method.

It is intended for dewatering and compaction, and can be applied to both clayey and sandy soils, and has both dewatering and compaction effects.

(3) Crushed stone drain pile method.

The purpose is to secure drainage and drainage channels.

(4) Other methods include the Chemico pile method, which aims to harden the ground, the CDM method, which mixes and mixes in-situ to deep layers to solidify, and the DJM method, which injects materials deep into the ground and solidifies them. There are CCP, JSO, jet grout method, etc.

Among the above construction methods, we will focus on vertical drain systems such as sand drains, paper drains, and crushed stone drains, and explain the details of their principles.

As shown in Figure 7, the vertical drain construction method involves driving vertical drainage columns (vertical drains) such as sand drains 4 made of highly permeable material at appropriate intervals in the soft ground 2 to consolidate the soft layer. The aim is to promote consolidation by shortening the drainage distance. Arrow 6 in the diagram
indicates groundwater seepage due to water pressure.

As shown in Fig. 8, the construction method is to position a hollow pipe as the casing 8 (A in liii) and insert it into the soft ground 2 (B in the figure), and then use a material with good water permeability (sand 1).
0) is applied (C) in the figure, the shoe 12 at the tip is opened while applying air pressure, and the casing 8 is pulled out (D in the figure) to create a vertical drainage column (sand drain 4) made of only water-permeable material (D in the figure). Middle E).

In the figure, 14 is the sand input port, and 16 is the air supply port.

18 is a sand mat (sand bed).

Sand drains 4 with such a column diameter dw are placed at an appropriate interval d.
In this case, an equilateral triangular arrangement as shown in Figure 9 (A) or (
Construction will be done in a square arrangement as shown in B).

Figure 10 shows the state of sand drain 4 after construction, and 2
0 is the overload load.

[Problem to be solved by the invention]

However, such construction methods require overloading in order to improve the volume change characteristics of the ground and increase its strength.
It does not have an improvement effect by itself.

In other words, the purpose of the vertical drain construction method is to promote consolidation and quickly improve the ground to be able to withstand the upper load. However, the principle of dewatering and drainage alone has limitations in rapid construction (shortening the construction period). There was a problem that there was.

In addition, there was a risk that the continuity of the drainage column could not be maintained after the casing was pulled out, such as not being able to maintain the diameter of the column as designed.

The purpose of the present invention is to provide a drain pipe that can be used for both ground reinforcement and ground reinforcement, which enables faster construction by adding a soil reinforcement effect that directly improves the drainage column in addition to the functions of dewatering and drainage. The objective is to provide an improved reinforcement method.

[Means to solve the problem]

The pipe of the present invention achieves the above object.

A pipe that is installed in soft ground, with multiple drainage holes arranged in the pipe wall, and the inside is filled with a highly permeable material such as sand, gravel, or a synthetic resin filter. This is what I did.

Moreover, the method of the present invention is a method of driving this pipe into soft ground. The inside of the pipe may be filled with a water-permeable material in advance, or may be filled during or after casting.

[Effect]

According to the above configuration, groundwater in the soft ground seeps out from the drainage hole of the pipe, dewatering and draining the soft ground, and the continuity and diameter of the drainage column are maintained.

The pipe also acts as a reinforcing material, increasing the overall strength of the soil mass through interaction with the soil.

〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

Note that parts having the same contents as those in the drawings of the conventional example are designated by the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows a pipe 100 showing an embodiment of the present invention, which is a single pipe having a diameter of 50Ila and having a plurality of pores ]-02. This pipe 100 is driven vertically into soft ground 2, and the inside is filled with high-quality sand 10, gravel, or a synthetic resin filter to increase water permeability.

Groundwater seeps out from the pores 102 as shown by arrow 6 in the figure.
Also, the pipe], 00 acts as a reinforcing material due to the peripheral frictional force shown by the arrow 104 in the figure and the tip support force shown by the arrow 1061 due to the interaction with the surrounding soil.

Figure 2 is an example of a construction method in which the pipe 100 of the above embodiment is applied to clay ground, and a sand 18
A five-stage embankment construction was carried out by laying pipes 100 on top of the pipes.

Embankment] -08 method T111 Q, the end 114 including the end of the slope 112 is reinforced by the tensile resistance of the pipe 100 to stabilize the slope.7 In this case, the pipe J-0
It is not necessary to limit the direction in which the 0 is implanted to the vertical direction.

The purpose of reinforcing the central portion 11.6 of the embankment J708 is to suppress the amount of settlement due to the compression resistance of the pipe 100. In the figure, 118 is the slip surface, 120 is the diluvial ground, and arrow 122
indicates the direction of the load.

Figure 3 shows the optimal insertion direction of pipe 1-00 for the purpose of tensile reinforcement in the ground beneath a structure. This resists destruction of the sliding surface 118.

These embodiments have the following effects.

(1) Dewatering and drainage action as a drainage column.

Compared to conventional drainage columns, using a perforated vibrator ensures continuity, column diameter, etc.

(2) Acts as a ground reinforcement material.

The interaction between the soil and the pipe increases the strength of the entire soil mass.

Figure 4 shows an example of a pipe 100 being driven into the ground vertically as a compression reinforcing material.If the compression force applied to the upper end of the pipe 00 is QT, then the shear road force on the surface of the pipe 100 τ and tip support force Q11, pipe 1
The compression force C applied to 00 is the maximum compression force CIIAM at the middle part.
Each of the 7 pipes increases the strength of the ground 2 as a compression reinforcement.

124 is an example in which the overload is a footing.

Further, FIG. 5 is an example in which the pipe 100 is used as a tensile reinforcing material, and as shown in the graph in the figure, the tensile force 'r applied to the pipe 100 reaches the maximum tensile force Tmax at the position where it intersects with the sliding surface 118, and the pipe It acts as a tensile reinforcing material due to the shear path force τ on the surface of 2.12G.

FIG. 6 is an explanatory diagram of the effect when the pipe 1,00 is installed horizontally directly under the footings 1,24.

In this case, the tensile force applied to the pipe 100 reaches its maximum at the center of the material.

The pipe 100 can be used as a reinforcing material for soft ground.

(3) Decrease in the amount of subsidence.

Due to the above-mentioned action as a reinforcing material, a portion of the overload is absorbed.

Since it is possible to reduce the load that is transmitted to the ground with a diameter of 100 mm or less and acts on the soft ground, it is possible to reduce the amount of consolidation settlement.

(4) Rapid construction becomes possible.

By acting as a reinforcing material, the reinforcement strength can be increased immediately after the vibrator of this embodiment is installed, so a large overlay load can be applied (rapid installation). In addition, part of this additional load is borne by the support force at the tip of the pipe] and OO, so it can be applied even more.
This will lead to rapid construction.

(5) Can be applied to sandy ground.

A problem with soft sandy ground is liquefaction during earthquakes. The pipe of this embodiment is installed to prevent the liquefaction phenomenon, and its dewatering and drainage action can suppress the generation of excessive pore water pressure.

〔Effect of the invention〕

As described above, the present invention has the following effects.

(1) Rapid construction is possible because dewatering, drainage, and reinforcement can be done simultaneously on soft ground.

(2) Workability is good because there is no need to pull out the casing.

(3) Compared to the rapid construction and good workability, it is more economical than conventional construction methods.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing an embodiment of the construction method, Fig. 3 is an explanatory diagram showing another embodiment of the construction method, and Figs. Figure 5 is an explanatory diagram showing the operation of the embodiment. Figure 7 is an explanatory diagram of the conventional example, and Figures 8 to 10 are explanatory diagrams showing the conventional construction method. 2... Soft ground, 4... Sand drain, 10
...Sand, 10o...Pipe, 102...
- Pore, 104... Frictional force, 106... Supporting force, 108... Embankment. 118...Touching face.

Claims (1)

[Scope of Claims] 1. A drain pipe that is installed in soft ground and has a plurality of drainage holes in the pipe wall and serves as ground reinforcement. 2. The drain pipe for ground reinforcement as set forth in claim 1, wherein the inside of the pipe is filled with a highly permeable material such as sand, gravel, or a synthetic resin filter. 3. The drain pipe for ground reinforcement as claimed in claim 1 or 2, wherein the pipe has a diameter of 40 to 150 mm. 4. A method for improving ground reinforcement, which comprises driving the drain pipe for ground reinforcement according to claim 1, 2 or 3 into soft ground. 5. A method for improving ground reinforcement, in which the drain pipe serving as the ground reinforcement according to claim 1 is driven into soft ground, and the inside of the pipe is filled with a water-permeable material. 6. A method for improving ground reinforcement, comprising driving the drain pipe for ground reinforcement according to claim 1 into soft ground, and then filling the inside of the pipe with a water-permeable material.