JP2000192445A - Consolidation construction method for soft ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a seepage flow in soil water without requiring a large-scale facility, and to promote the consolidation of a ground by setting a drainage boundary and a pressure-water boundary to each of both ends of the soft ground to be improved, driving a drainage material on the drainage boundary side and injecting a pressure fluid into the ground from the pressure boundary side. SOLUTION: One of an improving range surrounded by the boundary of an adjacent land is used as a drainage boundary and the other as a pressure boundary, vertical drain materials 1 are driven on the drainage boundary side at regular intervals, and water-pouring holes 2 at the same pitch in approximately the same depth are excavated on the pressure boundary side. Hydrostatic pressure is generated in pressure distribution corresponding to water-pouring depth towards the drainage boundary side in the ground E by pouring water into the water-pouring holes 2 through a pump 3, and detained soil pore water is made to flow to the drainage boundary side because osmotic pressure difference by the hydrostatic pressure is generated between the drainage boundary and the pressure boundary, and ejected to a ground surface section by the capillary phenomenon of the vertical drain material 1. Ejected soil water is collected to a drain pipe 4 in the periphery of the vertical drain material 1 and discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement method, and more particularly to a consolidation method utilizing an osmotic pressure difference.

[0002]

2. Description of the Related Art As a countermeasure against residual settlement of soft ground, a loading method is known. In this method, an embankment is constructed in advance as a load on a soft ground, and the ground is consolidated by the earth pressure of the embankment. On the contrary, there is also known a method in which a vertical drain material is poured into soft ground, the surface of the ground is covered with an airtight sheet, and the inside of the covered area is vacuum-sucked.

[0003]

However, each of the above methods has the following technical problems. First, the loading method requires a long time to stabilize the ground, and the effect of the load extends to the periphery of the embankment construction, and as a result, the surrounding portion also sinks. In addition, as a countermeasure, the area of the loading embankment should be kept away from the surrounding works, or measures to prevent deformation such as partitioning work should be taken to prevent the ground deformation accompanying settlement mainly at the boundary with the surrounding works. Needed and had extra construction costs.

[0004] Although the vacuum suction method is suitable for rapid construction, it requires equipment and materials such as a vacuum pump and an airtight sheet, and the range of improvement by one-time construction is narrow depending on the sheet area.

[0005] By the way, the inventor of the present invention has reported that, when viewed from a microscopic viewpoint, the properties of water in soft ground are such that individual soil particles are gelled in a state of retaining pore water in the soil, and while maintaining equilibrium in this state. Focusing on the stagnant state, he conceived that it is possible to drain and consolidate soil moisture as follows.

In other words, if an osmotic pressure difference is generated from this equilibrium state, the stagnant interstitial water can flow toward the side having a lower osmotic pressure. The ground can be densified without using a load, vacuum suction, or the like.

[0007] The present invention has been made based on the above viewpoints, and an object of the present invention is to form a permeation flow in soil water by osmotic pressure at an early stage without requiring large-scale facilities, and to consolidate the ground. An object of the present invention is to provide a consolidation method in soft ground which can be accelerated.

[0008]

In order to achieve the above objects, the method of the present invention sets a drainage boundary and a pressurized water boundary at both ends of the soft ground to be improved, and discharges a drainage material on the drainage boundary side. And pressurized fluid is injected into the ground from the pressurized boundary side.

As described above, in the method of the present invention, by injecting the pressurized fluid, the equilibrium of the water in the ground moves to the drain boundary side, and the ground is drained to the surface through the drain material at this position. Form a seepage flow to consolidate the ground.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an example of equipment arrangement on soft ground E for implementing the method of the present invention. In the figure, the improvement range is the interior surrounded by the adjacent land boundary, one of which is the drainage boundary (1), the other is the pressurized boundary (2), and the drainage boundary (1) is , A vertical drain material 1 such as a plastic drain is placed at predetermined intervals in a direction perpendicular to the plane of the drawing, and water injection holes having substantially the same pitch and substantially the same depth are provided on the pressure boundary (2) side. 2 is excavated.

After the above preparation work, water is injected into the water injection hole 2 via the pump 3. Due to the water injection, hydrostatic pressure is generated inside the ground E toward the drainage boundary side (1) in a pressurized distribution according to the water injection depth, as indicated by an arrow, and the osmotic pressure difference due to the hydrostatic pressure causes the drainage boundary (1). As a result, water is retained inside the ground, and the interstitial water that has been stagnated because the equilibrium is maintained flows to the drainage boundary side (1), which is the low pressure side. Then, due to the capillary phenomenon of the vertical drain material 1 located here, water is absorbed on the ground surface side,
Ejects to the surface.

On the surface of the ground, around the vertical drain material 1, a drain pipe 4 with an open top is laid.
The spouted soil water is collected in the drain pipe 4 and discharged out of the system through the drain pipe 4.

Further, in the present invention, when the range of water injection into the water injection hole 2 by the pump 3 is close to the surface layer, the possibility of jetting substantially to the surface layer increases, and the compaction effect may be reduced. Is preferably a relatively deep portion.

As a result of the above-described drainage action, a seepage flow is formed in the pore water in the soil, and the ground is compacted. Therefore, the improvement can be performed without affecting the adjacent land boundary.

Although a part of the water injected into the ground E through the water injection hole 2 penetrates into the ground, the leakage amount is very small as compared with the drainage amount of the underground pore water. The influence on the increase and decrease of the internal water is very small, and once the water is injected, it is sufficient to supply the water every time the water level decreases.

Therefore, even if the present method alone is used, a sufficient ground improvement effect can be obtained. However, prior to the other improvement methods, the above-described improvement method is performed as a preliminary method, and then another method is used in combination. Thus, as a matter of course, the burden can be reduced as compared with the case where another improvement method is performed alone.

Further, in the above embodiment, water is used as the pressurized fluid. However, for example, muddy water or pressurized air can be used, and in other words, it is possible to generate a permeation flow due to an osmotic pressure difference. Any medium can be used.

[0018]

As is clear from the above description, according to the consolidation method for soft ground according to the present invention, the drainage of soil moisture can be promoted by the osmotic pressure without the need for large-scale equipment at an early stage, and the consolidation can be performed. Can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an example of equipment arrangement by a ground consolidation method of the present invention.

[Explanation of symbols]

 (1) Drainage boundary (2) Pressurization boundary 1 Vertical drain material 2 Water injection hole 3 Pump E Soft ground

Claims (1)

[Claims] 1. A drainage boundary and a pressurized water boundary are set at both ends of a soft ground to be improved, and a drainage material is cast on the drainage boundary side, and a pressurized fluid is injected into the ground from the pressurized boundary side. Consolidation method in soft ground characterized by performing.