JPH08189030A - Method for constructing self-supporting earth-retaining wall - Google Patents

Abstract

PURPOSE: To reduce the size of cores and to decrease the number of piles so as to increase resistance to side pressure by placing lines of hollow soil cement piles on the outside of a line of core-containing soil cement piles, and driving a well point into the ground between both lines of piles for pumping up underground water. CONSTITUTION: In a portion of a small excavation depth surrounding a low- water-pressure area A, a line of normal soil cement piles (a) is provided while steel cores (b) of H-section are inserted into every one soil cement pile (a). Double lines of soil cement piles are provided on the outer periphery of a high- water-pressure area B and up to a position a predetermined distance into the area A from both ends of the area B; i.e., the lines 2 of hollow soil cement piles are placed at a predetermined distance D to the outside of the line of core-containing soil cement piles obtained by insertion of the steel cores (b) of H-section into the soil cement piles (a). A well point 30 is driven to a predetermined depth into the ground between both lines 1, 2 of piles to pump up underground water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a self-supporting retaining wall by a row of soil cement columns in civil engineering work.

[0002]

2. Description of the Related Art In general, in a self-supporting earth retaining wall made of pillar columns of soil cement pile (earth retaining wall without beams), each soil cement pile (pile made of soil cement in which cement milk and excavated soil are mixed) or 1 A steel core material such as an H-shaped steel was embedded in a soil cement pile of every other book so as to counteract earth pressure.

However, under the condition that the excavation depth is deep and the groundwater level is high, the lateral wall pressure is large and the column wall itself cannot be self-supporting, so that self-supporting earth retaining cannot be performed. Also, since the water pressure becomes large, a water leakage accident may occur from a slight gap between the soil cement piles. When the ground was soft, a root cutting depth of about 5 m was the limit depth for self-supporting mountain retaining.

In order to solve the above-mentioned drawbacks, Japanese Patent Laid-Open No. 6-24
A "self-supporting mountain retaining wall with a pile pile column" disclosed in No. 0662 was proposed.

The above invention, as shown in FIG. 4, is a coreless soil cement in which a steel core material b is inserted. A coreless soil cement in which the steel core material b is not inserted outside the pile column array 1. The pile column array 2 was constructed with a space L.

In the above invention, the inner core soil cement pile column row opposes the earth pressure and the water pressure which the outer coreless soil cement pile row opposes, and the inner cored soil cement pile column row opposes the groundwater leakage. A row of unlined soil cement pile columns will be opposed. That is, the inner core soil cement pile column row, since the steel core material is inserted, while it can withstand a large lateral pressure, the steel core material and the soil cement pile, the resistance force to the lateral pressure and the amount of deformation Since they are different, cracks may occur in the soil cement pile portion, or the steel core material and the soil cement pile may peel off, and it is difficult to secure the waterproof performance. On the other hand, since the outer coreless soil cement pile column is not inserted with the steel core material, it cannot withstand a large lateral pressure, but the lateral pressure deforms the whole into a uniform state and suppresses the occurrence of cracks and the like. Will be. Therefore, a high water-stop performance was ensured by the combination of both.

[0007]

The side pressure acting on the self-supporting retaining wall is the sum of earth pressure and water pressure, but in the ground where the groundwater level is high, most of the side pressure is water pressure. Therefore,
In the conventional self-supporting mountain retaining wall, in the case of the ground having high water stopping performance but high groundwater pressure, the cored soil cement pile column row 1 into which the inner steel core material b is inserted is made to have considerable strength. It is necessary to increase the diameter of the soil cement pile a and also to increase the steel core material b, which is not only time-consuming in terms of construction but also expensive.

The present invention has been made in view of the above-mentioned circumstances, and is a coreless soil cement pile column 1 in which a steel core material is inserted and a coreless steel core material is not inserted in the outside. (EN) A method for constructing a self-supporting retaining wall that overcomes the conventional drawbacks by providing a soil cement pile pillar row 2, constructing a well point between both pillar rows, and pumping groundwater.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a soil cement pile column column in which a steel core material is inserted, and a soil cement pile column in which the steel core material is not inserted at a predetermined distance outside the column. Rows are respectively placed, well points are constructed at a predetermined depth on the ground between the two pillar rows,
It is characterized by pumping groundwater.

Further, the construction depth of the well point of the present invention is not less than the root cutting depth.

[0011]

[Operation] When groundwater is pumped from the well point, the water level of the groundwater is lowered, so that the lateral pressure due to the water pressure applied to the column in which the inner steel core is inserted is reduced and the well point effect is fully exhibited. Therefore, water leakage due to root cutting is completely eliminated. In addition, when the groundwater level drops, the mechanical characteristics of the ground surrounded by the inner and outer columns are greatly improved, so the inner and outer columns and the ground between them are integrated and behave like a composite member. Therefore, a large resistance force can be exerted against the lateral pressure acting on the outer column row.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a plan view illustrating a construction method of a self-supporting mountain retaining wall showing an embodiment of the present invention, FIG. 2 is a partial plan view showing an embodiment of the present invention, and FIG. 3 is a sectional view showing an embodiment of the present invention. . In FIG. 1, A is a region where the excavation depth is shallow and the water pressure is low, and B is a region where the excavation depth is deep and the water pressure is high. Most of the self-supporting retaining wall surrounding the area A is a normal single row of soil cement pile columns in which a steel core b of H-shaped steel is inserted into every other soil cement pile a, but area B The outer peripheral portion and the self-supporting mountain retaining wall that is placed from both ends of the area B into the area A by a predetermined distance form a double soil cement column row.

That is, H is added to each soil cement pile a.
A so-called coreless soil cement pile column row 2 in which the steel core material b is not inserted in the soil cement pile a outside the core cement pile column row 1 into which the shaped steel core material b is inserted Are placed at a predetermined distance D. In the illustrated embodiment, the inner core soil cement pile column array 1 and the outer coreless soil cement pile column array 2 are connected to each other at both ends as shown in FIG. In the case of extending the double soil cement pile column row to the position where the pile column rows 1 and 2 are deeply inserted into the area A, both ends may not be connected as shown in the figure.

As shown in FIG. 3, the ground between the two pillar rows 1 and 2 has a predetermined depth and a predetermined depth (it is preferably more than the root cutting depth depending on the depth of the groundwater level). Well point 30 is driven in and groundwater is pumped. Well point is an overall length of about 1. made from a water-absorbing tube with a porous screen with an outer diameter of 5-8 cm and a length of 0.5-0.7 m.
The tip of a 0m small well, which is currently used is a self-jetting type that can be installed while ejecting water from the tip. Well point 30
It is driven to a predetermined depth with the riser pipe 12 connected to, and a drilling cutter is used when drilling is insufficient with only the jet. Then, a predetermined amount of sand filter is filled around the riser pipe 12.

Well points 30 are formed at predetermined intervals.
When is driven, the header pipe 10 is laid and the upper end of the riser pipe 12 and the header pipe 10 are connected by the swing join 11. Reference numeral 20 denotes a pumping device, which drains the water pumped by a vacuum pump by a fugal pump.

However, in the case where the column row has a large casting depth and therefore it is necessary to pump water from a deep stratum, pumping by a deep well can be performed. In this case, since a well having a large diameter is drilled and a submersible pump is installed at the bottom of the well to pump water, the construction diameter becomes large, and the distance D of the column-parallel pipe is set to be large accordingly.

However, as shown in FIG. 3, the groundwater level of A is lowered to the position of B between the columns 1 and 2. Therefore, not only the lateral pressure applied to the inner cored soil cement column row decreases, but also the mechanical characteristics of the part surrounded by the inner and outer column rows improve when the groundwater level decreases, so the inner and outer column rows and the ground between them are improved. It will be integrated and will behave like a complex ground.

[0018]

According to the present invention described in detail above, the following effects are exhibited. (1) Since the groundwater is drained inside the outer coreless soil cement pile column, the lateral pressure applied to the inner cored soil cement pile column is reduced, and the diameter of the column can be reduced.
Moreover, not only can the size of the steel core be designed to be small,
It is also possible to reduce the number of soil cement piles into which the steel core material is inserted. (2) When the groundwater level is lowered, the mechanical characteristics of the ground surrounded by the inner and outer pillar rows are significantly improved, so the inner and outer pillar rows and the ground between them are integrated, and the ground behaves like a composite ground. Therefore, a large resistance force is exerted against the lateral pressure acting on the outer column row. (3) Therefore, it is possible to economically construct a large-depth self-supporting mountain retaining work, which was not possible with the conventional technology. (4) Since the range of well points is limited, the effect is sure and complete, and even if the lap between the column rows is slightly defective, there is no risk of water leakage and reliable water stopping is possible.

[Brief description of drawings]

FIG. 1 is a plan view illustrating a method of constructing a self-supporting mountain retaining wall showing an embodiment of the present invention.

FIG. 2 is a partial plan view showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an embodiment of the present invention.

FIG. 4 is a plan view of a conventional self-supporting mountain retaining wall.

[Explanation of symbols]

 1 Soil cement pile column with core 2 Soil cement pile column without core 20 Pumping equipment 30 Well point a Soil cement pile b Steel core D Distance

Claims (2)

[Claims] 1. A row of soil cement pile columns in which a steel core material is inserted and a row of soil cement pile columns in which a steel core material is not inserted are placed outside of the soil cement pile column rows at a predetermined distance. A method for constructing a self-supporting retaining wall characterized by constructing well points at a predetermined depth at a predetermined depth in the ground between two pillar rows and pumping groundwater. 2. The method for constructing a self-supporting retaining wall according to claim 1, wherein the driving depth of the well point is deeper than the root cutting depth.