JPH0892959A - Head-section structure of earth retaining wall - Google Patents

Abstract

PURPOSE: To construct an earth retaining wall having high self-supporting properties by rigidly welding one end of a broad beam having a flexural rigidity approximately equal to the flexural rigidity of the earth retaining wall to the head section of the earth retaining wall through a circumferential girder and projecting the broad end to the mountain side in a type crossing at right angles with the earth retaining wall. CONSTITUTION: A continuous underground wall 1 or a column wall 6 as a earth retaining wall is constructed up to specified depth through a normal method of construction. The mountain-side ground of the earth retaining wall is compacted sufficiently, and broad beams 2 are built onto the surface of the ground and welded rigidly to the head section of the earth retaining wall. When the broad beams 2 are erected, reinforcements in the same quantity as the quantity of the reinforcements of the continuous underground wall 1 are arranged when the broad beams 2 made of reinforced concrete are joined with the head section of the continuous underground wall 1 consisting of cast-in-place reinforced concrete, circumferential girders 3 are arranged, and concrete is placed. When the broad beams 2 made of reinforced concrete are jointed with a column wall 6 through a method of soil cement construction, the arranged reinforcements of the circumferential girders 3 and broad beam steel frames 5 are installed to the head section of H-steel 4 as the core material of the column wall 6, and concrete is placed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head structure of a mountain retaining wall.

[0002]

2. Description of the Related Art Although mountain retaining walls are constructed by various construction methods,
The head of the head is constructed by connecting the head of the mountain wall with the head connecting beam by pouring the head or concrete.

[0003]

In root-cutting work when the basement is relatively shallow, it is necessary to omit the construction of a girder that interferes with the work and to use a mountain retaining wall with a cross-sectional area that is as small as possible. Required to do so. However, if the ground is soft, even if the root cutting depth is relatively shallow, a considerably large bending moment is generated in the retaining wall as shown in FIG. It is dangerous to reduce the cross-sectional area of the mountain retaining wall, and the emergence of highly self-sustaining mountain retaining wall is desired.

[0004]

SUMMARY OF THE INVENTION According to the present invention, one end of a wide beam having a bending rigidity substantially equal to that of a mountain retaining wall is rigidly contacted with the head of the mountain retaining wall to enhance the self-supporting property of the mountain retaining wall. It solves the problems of law all at once.

That is, according to the present invention, one end of a wide beam whose bending rigidity is substantially equal to that of the mountain retaining wall is rigidly contacted with the head of the mountain retaining wall through a girder so that the wide beam is orthogonal to the mountain retaining wall. It is related to the head structure of the mountain retaining wall that overhangs the mountain side.

Conventionally, it has been practiced to cast concrete on the head of a mountain retaining wall to construct a head connecting beam to connect the mountain retaining wall heads in the horizontal direction. This coupling acts on the mountain retaining wall. It is for transmitting the lateral pressure to the left and right adjacent mountain retaining walls after concentrating the lateral pressure on the mountain retaining wall heads.The mountain retaining wall head and the head connecting beam are pin joints in the vertical method. Bending moment is not transmitted between the two members.

Therefore, the bending moment of the conventional vertical method of the earth retaining wall is irrespective of whether or not the head connecting beam of the head of the earth retaining wall is constructed, as shown in FIG. It has a distribution of 0 in the vicinity, the maximum on the positive side in the central part of the mountain retaining wall, and the negative side on the hard ground of the rooting part. (Note that FIG. 2B shows the completion of the second root cutting when the first root cutting is the shallow root cutting for erection of the 0-step beam.

As described above, in the conventional mountain retaining wall, the distribution of the bending moment in the vertical method is extremely unbalanced between the positive side and the negative side. It is the head structure of the mountain retaining wall of the present invention that improves the balance between the positive side and the negative side.

According to the present invention, since the wide beam is rigidly contacted with the head of the retaining wall in the form of projecting to the mountain side, a vertical bending moment as shown in FIG. And bending moments generated in the wide beam and generated in both members are combined. The combined bending moment is the same amount M at the mountain retaining wall head and the wide beam end, and the amount of bending moment M is given to the mountain retaining wall head on the negative side.
The bending moment given to the negative side to the earth retaining wall head, the maximum bending moment of the positive side in the earth retaining wall central portion is reduced by substantially equal amounts of M ^'to M. That is, as a result, the lateral pressure applied to the mountain retaining wall is shared by the wide beams and is borne, and the magnitude of the positive side bending moment generated in the central portion of the mountain retaining wall is reduced accordingly. Along with that, the bending moment on the negative side of the rooting part is reduced. As a result, the bending moments generated in the mountain retaining wall are gently distributed over the entire length of the mountain retaining wall in a well-balanced manner on the positive side and the negative side, the absolute amount of which is small, and the amount of deformation of the mountain retaining wall is also small.

In order to make the bending rigidity of the wide beam and the bending rigidity of the retaining wall of the present invention substantially equal, for example, when the retaining wall is a continuous underground wall made of cast-in-place reinforced concrete, the wide beam is connected to the continuous underground wall. It is sufficient to make a reinforced concrete structure with approximately the same thickness and approximately the same amount of reinforcing steel. If the mountain retaining wall is a pillar row wall made by the soil cement method, it is almost the same as H-section steel with a wide beam inserted in the pillar row wall. A steel-framed concrete structure using H-shaped steel with the above performance may be used. The wider the width of the wide beam, the larger the bending moment that it bears will increase. However, if the root cutting depth is about 5 m, it is usually about 2 to 3 m. Widen.

As the mountain retaining wall of the present invention, those having the same bending performance inside and outside are preferable, and a continuous underground wall made of cast-in-place reinforced concrete, a column wall made of cast-in-place reinforced concrete, a column wall made by the soil cement method, etc. are preferably adopted. To be done.

It is not necessary that the flexural rigidity of the wide beam of the present invention and the flexural rigidity of the retaining wall be exactly matched. The head of the mountain retaining wall bears up to the holding bending moment of the member having the smaller bending rigidity among the members that are rigidly connected,
This is because it is not possible to bear bending moments beyond that. Since the mountain retaining wall is constructed first, it is common sense to construct the wide beam by matching the bending rigidity of the wide beam to the bending rigidity of the mountain retaining wall.

When constructing the earth retaining wall of the present invention and performing root cutting, the ground at the bottom of the wide beam is used as a reaction force. Therefore, when the mountain side soil of the mountain retaining wall is soft, rolling compaction, etc. Therefore, it is necessary to fully compact it.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows a joint example of a head portion of a mountain retaining wall according to the present invention. FIG. 1 (a) is a vertical sectional view of a joint portion between a continuous underground wall made of cast-in-place reinforced concrete and a wide beam made of reinforced concrete. [Fig. 3] is a perspective view of a joint between a column wall made by the soil cement method and a wide beam made of steel-framed concrete, and Fig. 8C is a vertical cross-sectional view of Fig. 7B.

When the wide beam 2 made of reinforced concrete is joined to the head of the continuous underground wall 1 made of cast-in-place reinforced concrete, as shown in (a), the same amount of reinforcing bars as that of the continuous underground wall 1 is used. After arranging and laying the girder 3, the wide beam 2 is constructed by placing concrete. In addition, 7 is a concrete joint surface.

When a steel-concrete wide beam is joined to the column wall 6 by the soil cement method, as shown in (b), a girder is placed on the top of the H-shaped steel 4 which is the core material of the column wall 6. After the reinforcement of 3 and the installation of wide beam steel frame 5,
As shown in (c), concrete is poured to construct a wide beam. In addition, illustration of the column wall 6 is abbreviate | omitted in (b). Further, 7 is a concrete jointing surface.

An example of constructing the mountain retaining wall of the present invention and performing root cutting will be described.

First, the continuous underground wall 1 or the pillar row wall 6 which is a retaining wall is constructed to a predetermined depth according to a usual construction method. Then, the mountain side ground of the mountain retaining wall is sufficiently compacted, and a wide beam is constructed on the surface by any of the methods shown in FIG. 1 to rigidly contact the mountain retaining wall head. Normally, it is not necessary, but if the site area is large, excavate the inside of the retaining wall very shallowly (first root cutting) and erection a zero-level beam as close to the ground surface as possible to carry out the second root cutting. To do.

FIG. 2 is a vertical cross-sectional view of the periphery of the mountain retaining wall, showing the bending moment distribution generated at the time of root cutting. (A) is a mountain retaining wall of the structure of this invention, (b)
Is the case where wide beams are not used.

In the case of FIG. 2 (a), a negative bending moment is generated in the wide beam rigidly contacted with the head of the mountain retaining wall, and a bending moment corresponding to that is generated in the central portion of the mountain retaining wall. It can be seen that the bending moment is reduced.
Comparing (a) and (b), it is clear that the distribution of bending moment is gentler in (a), the absolute amount is smaller, and the positive and negative sides are distributed in good balance. In addition,
In the case of (a), in most cases, it is not necessary to erection a 0-step beam, but in order to match with (b), it is illustrated as having a 0-step beam.

[0022]

EFFECTS OF THE INVENTION With the mountain retaining wall head structure of the present invention, the bending moment distribution generated in the mountain retaining wall is small over the entire length, and the positive side and the negative side are well balanced, so the amount of deformation of the mountain retaining wall is also small. The following effects can be achieved.

(1) When the root cutting depth is relatively shallow and the site area is not large, the mountain retaining wall becomes a self-supporting mountain retaining wall, and it is not necessary to erection a girder to improve the workability, material cost and construction cost. Is reduced.

(2) Even when the root cutting depth is relatively deep and the site area is large, it is sufficient to construct the mountain retaining wall with a simple cutting beam, and as in (1), the workability is improved and the material cost is increased. , Construction costs are reduced.

(3) The adverse effect on the surrounding ground such as the subsidence of the ground is greatly reduced.

[Brief description of drawings]

FIG. 1 shows an example of joining the mountain retaining wall head of the present invention, (a)
Is a longitudinal sectional view of a joint between a continuous underground wall made of cast-in-place reinforced concrete and a wide beam made of reinforced concrete,
(B) is a perspective view of a joint between a column wall made by the soil cement method and a wide beam made of steel-framed concrete, and (c).
[Fig. 3] is a vertical sectional view in the case of (b).

FIG. 2 is a vertical cross-sectional view around a mountain retaining wall, showing a bending moment distribution generated at the time of root cutting.
(A) is the case of the mountain retaining wall of the structure of this invention, (b) is the case where a wide beam is not adopted. 1 ... Continuous underground wall, 2 ... Wide beam, 3 ... Woor, 4 ...
Pillar wall H-shaped steel, 5 ・ ・ Wide beam steel frame, 6 ・ ・ Column wall,
7 ... Concrete joint surface.

Claims (3)

[Claims] Claim: What is claimed is: 1. One end of a wide beam whose bending rigidity is substantially equal to that of a mountain retaining wall is rigidly contacted with the head of the mountain retaining wall via a girder, and the wide beam is projected to the mountain side in a form orthogonal to the mountain retaining wall. The head structure of the mountain retaining wall. 2. The head structure of the retaining wall according to claim 1, wherein the retaining wall is a continuous underground wall made of cast-in-place reinforced concrete, and the wide beam is made of reinforced concrete. 3. The head structure of the mountain retaining wall according to claim 1, wherein the mountain retaining wall is a column wall formed by a soil cement method using H-shaped steel as a core material, and the wide beam is made of steel frame concrete.