JPH1150478A - Filtering ground method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve drainage by forming a lightweight stone crushed layer having specific gravity on the rear face side of a retaining wall, and forming a lightweight soil layer having specific gravity between the lightweight stone crushing layer and backfilling soil. SOLUTION: A lightweight soil layer 27 which is composed of sufficiently compacted lightweight soil and whose specific gravity is smaller than 1 and a lightweight stone crushed layer 23 which is composed of lightweight crushed stone and whose specific gravity is smaller than 1 are formed between a retaining wall 21 and backfilling soil 22. Three draining holes 24, 25, 26 are substantially horizontally formed on the retaining wall 21. Water permeated from the backfilling soil 22 quickly flows in the lightweight soil layer 27 to flow in the lightweight stone crushed layer 23. Water flowed in the lightweight stone crushed layer 23 quickly lowers down to the lower layer of the lightweight stone crushed layer 23 and is flowed out from the draining hole 26 of the retaining wall 21 mainly as it always remains clean water. Thereby since water permeating the backfilling soil quickly flows without washing away the soil of the lightweight soil layer 27, it is excellent in drainage and ground settling does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a filtering ground method, and more particularly to a backfill method for retaining walls.

[0002]

2. Description of the Related Art FIG. 2 schematically shows the structure of a backfill layer of a conventional retaining wall. In the illustrated backfill layer, the specific gravity of crushed stone is about 1.6 between the retaining wall 14 and the sufficiently compacted backfill soil 42.
Crushed stone layer 43 is formed. The retaining wall 41 has a plurality of drain holes, for example, three drain holes 44, 45 and 46 formed substantially horizontally.

[0003]

In the backfill layer described above,
Usually, the specific gravity of the backfill soil 42 is about 1.2, which is larger than the specific gravity of water, so that the water flows into the crushed stone layer 43 while slowly penetrating the backfill soil 42. The specific gravity of the crushed stone layer 43 is also about 1.
6, which is larger than the specific gravity of water, the water flowing into the crushed stone layer 43 mainly forms a flow in the upper layer of the crushed stone layer 43. As described above, the water that has infiltrated from the backfill soil 42 flows into the crushed stone layer 43 together with the earth and sand while flowing the earth and sand of the backfill soil 42, and mainly drains 44 while containing a large amount of soil and sand.
Will be spilled from. As a result, there is a problem that the ground subsides, the ground is easily liquefied, and the drain holes are clogged and the drainability is impaired. Therefore, an object of the present invention is to provide a filtering ground method that is excellent in drainage properties and does not cause land subsidence, particularly, a retaining wall backfill method.

[0004]

According to the present invention, a lightweight crushed stone layer formed on the back side of a retaining wall and having a specific gravity of less than 1;
A lightweight soil layer formed between the lightweight crushed stone layer and the backfill soil and having a sufficiently compacted specific gravity of less than 1; wherein water permeating the backfill soil quickly penetrates through the lightweight soil layer; A filtering ground method, wherein the method reaches a lower layer of a lightweight crushed stone layer and flows out of a drain hole formed in the retaining wall while always maintaining clean water.

[0005]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a filtering ground method according to the present invention. FIG. 1 is a schematic diagram for explaining a backfilling method of a retaining wall, which is one embodiment of a filtering ground method according to the present invention. In the illustrated backfill layer, the retaining wall 21
A light-weight soil layer 27 made of sufficiently compacted light-weight soil and having a specific gravity of less than 1 and a light-weight crushed stone layer 23 made of light-weight crushed stone and having a specific gravity of less than 1 are formed between the soil and the backfill soil 22. The retaining wall 21 has a plurality of drain holes, for example, three drain holes 24, 25, and 26 formed substantially horizontally. The main difference between the method for backfilling the retaining wall of the present invention and the conventional method shown in FIG. 2 is that the backfill layer is composed of two layers smaller in specific gravity of water. As mentioned above,
In the backfill layer of the present invention, since the specific gravity of the lightweight soil layer 27 is smaller than the specific gravity of water, the water that has infiltrated from the backfill soil 22 quickly flows through the lightweight soil layer 27 and enters the lightweight crushed stone layer 23.
Further, since the specific gravity of the lightweight crushed stone layer 23 is smaller than the specific gravity of water, the water flowing into the lightweight crushed stone layer 23 quickly descends to the lower part of the lightweight crushed stone layer 23. That is, the water that has passed through the backfill soil 22 flows quickly without flowing the soil of the lightweight soil layer 27, descends to the lower part of the lightweight crushed stone layer 23, and is always drained from the retaining wall 21 while maintaining clean water. Runs out of 26.

As the light soil and the light crushed stone, it is preferable to use Aquasoil (trade name, manufactured by Ikegami Shoten Co., Ltd.), which is a known soil conditioner. Aquasoil is a well-known soil conditioner obtained by adding activating agents necessary for plant growth, minerals, fluorine, manganese, molybdenum, and other trace elements to granules obtained by crushing perlite and granulating at high temperatures. is there. The details of Aquasoil are described in Japanese Utility Model Application Laid-Open No. 63-186150. The specific gravity of the lightweight soil layer and lightweight crushed stone layer using Aquasoil is about 0.5.
5 In the above embodiment, the backfill method of the retaining wall is shown, but it is obvious that the filtered ground method of the present invention can be applied to other ground methods in which the settlement of the ground is avoided and the drainage property must be ensured. is there.

[0007]

As described above, in the filtration ground method according to the present invention, since the specific gravity of the two layers constituting the base layer and the backfill layer is smaller than the specific gravity of water, the permeated water quickly forms the two layers. As the water flows and is drained in a clean state, the ground does not sink and the drainage performance is not impaired.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for backfilling a retaining wall according to the present invention.

FIG. 2 is a schematic view illustrating a conventional retaining wall backfilling method.

Claims (1)

[Claims] 1. A lightweight crushed stone layer having a specific gravity of less than 1 formed on the back side of a retaining wall, and a lightly compacted soil having a specific gravity of less than 1 formed between the lightweight crushed stone layer and the backfill soil. Water that has penetrated the backfill soil quickly penetrates the lightweight soil layer, reaches the lower layer of the lightweight crushed stone layer, and flows out of the drainage hole formed in the retaining wall with clean water at all times And a filtration ground method.