JPH06294136A - Soil improvement pile - Google Patents

Abstract

PURPOSE:To reinforce a bearing capacity of a foundation ground in a soft ground by enveloping an outer peripheral surface of large-sized gravel piles prepared under a post of a structure with a material having a specified strength and durability. CONSTITUTION:With an earth drilling machine or the like, a pile hole 2 is excavated in a soft ground A under a post where the load of a structure is concentrated. A bag-attached cage 5 made of a mesh sheet is mounted to a reinforcing bar frame 3 and inserted into the pile hole 2. Then, gravels 6 are filled in the cage 5, thereby building a gravel pile. A gravel mat 7 is spread to a foundation where blind concrete is cast on the mat 7, thereby building up a structural skeleton B in the order of a pressure resistant board 8 and an underground beam 9 and the foundation. Then, when this is aplied to a soft cohesive soil gound, if the other part which excludes a soil improvement pile sinks, the load is concentrated on the gravel pile made of large-sized gravels 6 so that the gravel pile 6 is bulged horizontally so that it may work again as a direct foundation as a whole and stabilize the foundation ground gradually. This construction makes it possible to reinforce a bearing capacity of the foundation ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soft ground such as soft and viscous ground and liquefied sand ground, and ground improvement piles.

[0002]

2. Description of the Related Art In the case of the soft and viscous ground and the loose sand that is liquefied, it is common to use a pile foundation.

[0003]

It is uneconomical to design a 2-3 floor building with a pile foundation in the soft ground as described above, and it is better to use the foundation directly even if the ground is improved. Often economical. In addition, since the pile does not follow the consolidation settlement of the cohesive soil or the compression settlement of the sand layer due to liquefaction, voids occur under the foundation of the structure.

The present invention has been proposed in view of the above problems of the prior art, and an object of the present invention is to provide a ground improvement pile which is capable of strengthening the bearing capacity of the foundation floor and taking measures against liquefaction in soft ground. It is in the point of providing.

[0005]

In order to achieve the above-mentioned object, the ground improvement pile according to the present invention has the required strength and durability for the outer peripheral surface of a large-diameter gravel pile formed under a pillar of a structure. It is covered with a material having properties. According to the invention of claim 2, the outer peripheral surface of the gravel pile is covered with a mesh sheet having sufficient strength and resistance.

[0006]

The ground improvement pile according to the present invention is composed of a large-diameter gravel pile formed under a column where a load is concentrated, and its outer peripheral surface is composed of a material having a required strength and durability such as a mesh sheet. Therefore, when applied to soft and viscous ground, when the parts other than the soil improvement piles sink, the load is concentrated on the soil improvement piles and the load is applied to the soil improvement piles composed of large-diameter gravel piles. Concentration, as a result of which the gravel stakes swell to the side and once again act as a direct foundation as a whole. By repeating the above, the foundation ground will gradually stabilize.

On the other hand, with respect to liquefaction of soft ground such as sand ground, even if the ground is temporarily liquefied during an earthquake, the gravel pile covered with a material having the required strength and durability can stand on its own. At the same time, it serves to prevent liquefaction by extracting the pore water of the soft ground and functioning as a drain that dissipates the pore water pressure.

[0008]

The present invention will be described below with reference to the illustrated embodiments. Soft ground A under the column where the load is concentrated in the structure
In addition, the pile hole 2 is excavated by the excavation bucket 1 using an earth drill machine or the like (see FIG. 1 (a)).
A rebar cage 5 with a bag made of a mesh sheet 4 or the like is attached to the rebar frame 3 and inserted. (See FIG. 1 (b)) Next, as shown in FIG. 1 (c), the reinforced concrete basket 5 with the bag is attached to the gravel 6
To build a gravel pile, and lay a gravel mat 7 (gravel mat) on the foundation. (Refer to FIG. 1D) Waste concrete is placed on the gravel mat 7 to construct the structure skeleton B in order from the pressure plate 8, the underground beam 9 and the foundation. In the figure, 10 is groundwater.

Since the illustrated embodiment is constructed as described above, in the soft and viscous ground, when the parts other than the ground improvement piles sink, the load concentrates on the ground improvement piles, and as a result, it is better than the gravel piles. The constructed soil improvement pile swells in the lateral direction and again acts as a direct foundation as a whole. By repeating the above, the soft ground A gradually becomes stable.

On the other hand, with respect to the liquefaction of sand ground, even if the ground is liquefied temporarily, the gravel pile covered with the mesh sheet 4 becomes self-supporting and, at the same time, the pore water pressure is dissipated. Acts as a drain and also acts as a liquefaction prevention. C in the figure is a stabilized stratum that does not liquefy.

[0011]

As described above, the ground improvement pile according to the present invention is made of a material having a required strength and durability such as a mesh sheet on the outer peripheral surface of a large-diameter gravel pile formed under a pillar of a structure. Since it is constructed by covering with, the soft clay ground can suppress the settlement by lowering the ground improvement pile under the pillar to a certain level of the ground, and the uneven settlement can be reduced.
Further, since the ground improvement pile of the present invention is composed of gravel piles, when stress concentration occurs, sinking of the pile occurs and stress can be redistributed.

Further, in the loose sand ground, even if the ground soil is liquefied in the event of an earthquake, the gravel pile forming the ground improvement pile of the present invention is firmly self-supporting so that the structure does not tilt or fall. When the earthquake subsides and subsidence occurs, the gravel pile will also be deformed and directly return to the foundation.

[Brief description of drawings]

1 (a), (b), (c), and (d) are vertical cross-sectional views showing a process of constructing a soil improvement pile according to the present invention.

FIG. 2 is a vertical sectional view of a foundation portion of a structure using the ground improvement pile.

3 (a), (b), (c), and (d) are plan sectional views of each foundation pile of the structure of FIG.

[Explanation of symbols]

 A Soft ground B Structure frame C Stabilized formation 1 Drilling bucket 2 Pile hole 3 Reinforcing frame 4 Mesh sheet 5 Reinforcing bar cage 6 Gravel 7 Gravel mat 8 Pressure plate 9 Underground beam 10 Groundwater

Claims (2)

[Claims] 1. A soil improvement pile, characterized in that the outer peripheral surface of a large-diameter gravel pile formed under a pillar of a structure is covered with a material having required strength and durability. 2. The ground improvement pile according to claim 1, wherein an outer peripheral surface of the gravel pile is covered with a mesh sheet.