JPH01250515A - Liquefaction-proof construction for weak ground - Google Patents

Abstract

PURPOSE:To discharge water coming out of pile head sections, to a specified place, by embedding drain piles consisting of gravels of crushed stones or the like, in weak ground, and by connecting the pile head sections to each other with drain pipes. CONSTITUTION:In weak sandy ground W, a plurality of drain piles 1 consisting of the gravels G of crushed stones or the like are embedded at mutually fixed intervals. Then, along the line of the drain piles 1, recessed grooves of a proper depth are excavated, and in the recessed grooves, the opening end sections of circular-pipe-formed drain pipes 2 are butted to the head section of the drain pile 1 in a state pushed slightly into the pile from both the sides in the diameter directions, and the head section of the drain pile 1 is connected to each other with the drain pipes 2. Besides, the drain pipes 2 at both the ends are extended outside the site. As a result, comparing with the case of forming a gravel mat on the ground surface, drainage can be executed by using a small quantity of gravels.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a method for installing a required number of drain piles made of highly permeable gravel (crushed stone, gravel, slag, etc.) in soft ground, especially sandy ground that is easily liquefied. By burying them, when the pore water pressure in the sandy ground increases during an earthquake, the moisture in the ground will be sucked up and discharged to the ground through these drain piles, thereby causing the sandy ground to lose its bearing capacity during an earthquake. Concerning construction methods to prevent liquefaction of soft ground to make the ground safe.

(Prior Art) In this type of construction method, water discharged to the ground through drain piles is generally caused to flow out of the ground of a predetermined site by means of a gravel mat laid on the ground surface. However, since this gravel mantle is laid almost entirely on the ground of the site, a large amount of gravel is required to form this mantle, which is one of the causes of soaring construction costs. .

Therefore, instead of such a gravel mat, we formed a permeable pit using gravel that connects the heads of each drain pile, and this permeable pit directs water discharged to the ground outside the site ground. A construction method that allows water to flow out is disclosed in Japanese Patent Application Laid-Open No. 56-89619.

This permeable pit requires only a small amount of gravel, which reduces construction costs.

(Problem to be Solved by the Invention) According to the above-mentioned enemy-like water-permeable pinto, since gravel is simply piled up in the enemy-like shape, this water-permeable pinto is likely to collapse if earth and sand is placed on top of it. In addition to this problem, when it rains, the soil particles from the rain invade the gravel gaps in the permeable pit and cause clogging, which causes water to leak through the permeable bit! There is a problem that drainage cannot be carried out effectively due to inhibition of the 8 functions.

The present invention aims to provide a method that can solve these problems.

(Means for Solving the Problems) In order to achieve the above object, the construction method of the present invention connects the heads of drain piles with each other by a drain pipe, and directs water drained from each drain pile head to this drain. It is characterized by being discharged to a predetermined location through a pipe.

(Example) An example of the construction method of the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, a drain made of gravel G such as crushed stone is installed on soft sandy ground W within a predetermined site A. A required number of piles 1 are buried at regular intervals. Then, on the surface side of the sandy ground W in which these drain piles l... are buried, a groove of an appropriate depth (not shown) is made, for example, along one row of drain piles lined up in the left-right direction as shown in Fig. 1. dig,
Then, the circular drain pipes 2 are fitted into these grooves, and the open end of each drain pipe 2 is abutted against the head of the drain pile 1 so that it slightly protrudes from both sides in the diametrical direction. , connect the heads of drain pile 1 to drain pipe 2
Connect by. It is desirable to attach a net-like body 3 to the open end surface of each drain pipe 2 as shown in FIG. 2 so that the gravel G of the drain pile 1 does not flow into the drain pipe 2.

Also, as is clear from Figure 1, the drains 22.2 at both ends
is appropriately extended outside the predetermined site A.

In this way, drain pile 3... is connected to drain pile 1...
- Once the frames have been placed on the head, earth and sand are poured over them to form, for example, a base layer T.

According to the sand ground W improved by the construction method described above, when the pore water pressure of the sand ground W increases during an earthquake, water in the sand ground iW is sucked up to the above ground through each drain pile 1, and The water is drained from the head of the pile 1, and the drained water is received by each drain pipe 2 connected to the head of the drain pile 1, and is appropriately discharged outside the predetermined site A through the drain pipe 2. , thereby preventing liquefaction of the sandy ground W. In such a case, even if the base layer T is muddy due to rain or the like and the drain pipe 2 is submerged in muddy water, the muddy water will not directly enter the drain pipe 2, and therefore the drain There is no fear that the pipe 2 will become clogged and its drainage action will be inhibited. In addition, since the net-like body 3 is stretched on the open end surface of the drain pipe 2 connected to the head of each drain pile 1, the gravel G of the drain pile 1 is inside the drain pipe 2.
There is no fear that this head part will collapse due to water flowing into it. Incidentally, even if some gravel G gets into the drain pipe 2, it will not affect the drainage action. Therefore, it is not necessarily necessary to attach the mesh body 3 to the open end of the drain pipe 2.

The drain pipe 2 is made of metal pipe material such as steel pipe,
A pipe material made of synthetic resin can be used, and the diameter of the drain pipe 2 can be arbitrarily selected. Drain piles are constructed by inserting a rotationally driven casing with screws on the outer circumferential surface or a casing driven by an exciter into the ground to a predetermined depth, and filling the casing with gravel. , can be created by applying pressure to the filled gravel and then pulling out the casing.

In this example, an example was explained in which the drain pile was buried so that its head was almost located near the ground.
As illustrated in Fig. 3, in the case of the ground W' of a building site having a basement, such as the second or third floor, a concave portion 4 of considerable depth is excavated from the ground. For the drain pile 11 to be buried in the ground W', the horizontal pipe portion 12a of the drain pipe 12 is buried in the soil floor 5 formed by pouring concrete or the like into the bottom of the recessed portion 4, and The horizontal pipe part 12a is connected to the head of each drain pile 11 as shown in the figure, and this drain pipe 12a
A vertical pipe part 12b is connected to the vertical pipe part 12b, and another horizontal pipe part 12 is connected to this.
C is connected to release the tip of this horizontal pipe portion 12c onto the ground. According to this, the water sucked up through each drain pile 11 is transferred from the horizontal pipe part 12a in the earthen floor 5 to the vertical pipe part 12a.
b and horizontal pipe section 12c, and is discharged to the ground outside the predetermined site.

(Effects of the Invention) According to the present invention, the heads of the drain piles are connected to each other by drain pipes, and water drained from each drain pipe head is discharged to a predetermined place through the drain pipes. Unlike conventional construction methods, gravel for drainage is not deposited over the entire upper surface of the ground where drain piles are buried, reducing material and labor costs associated with the use of gravel. It is possible to expect a significant reduction in costs, and there is no risk of it collapsing when covering the top of the drain pipe with earth and sand, unlike conventional water-permeable bits. Sediment, etc. covering the drain pipe becomes mud-like and prevents the intrusion of dirt, etc. into the inside of the drain pipe, which prevents clogging inside the drain pillow, thereby fully demonstrating its drainage function. This allows for good drainage.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along line nn of FIG. 1, and FIG. 3 is a longitudinal sectional view showing another embodiment. w, w'...soft sandy ground, G...gravel, l. 11...Drain pile, 2.12...Drain pipe, 3
...Fluid body.

Claims (1)

[Claims] In a method for preventing liquefaction of soft ground, a required number of drain piles made of gravel or other gravel are buried in soft ground, and moisture in the soft ground is sucked up and discharged to the ground through these drain piles. A liquefaction prevention method for soft ground characterized by connecting the heads of each drain pile with a drain pipe, and draining water overflowing from each drain pile head to a predetermined location through the drain pipe.