JP3521363B2 - Mountain retaining method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a mountain cleat necessary to support the surrounding ground and prevent collapse or harmful deformation during underground excavation work.

[0002]

2. Description of the Related Art A mountain retaining structure is a structure necessary to support the surrounding ground and prevent collapse and harmful deformation during underground excavation work. The mountain retaining wall is, as shown in FIG. 8, a mountain retaining wall 1
And a supporting structure 4 such as a cross beam 3 and an abdomen upright 2 . An external force (earth pressure and water pressure) from the ground J on the back surface acts on the mountain retaining wall 1, but the mountain retaining wall 1 is supported by the excavated ground on the inside and the supporting works 4.

By the way, even if underground excavation is carried out after such mountain retaining, if the surrounding ground is a soft cohesive ground, phenomena such as deformation of the mountain retaining wall and subsidence of the surrounding ground are remarkable. appear. Fig. 9 shows an example of displacement of the retaining wall during excavation. In order to prevent these phenomena, it is very effective to increase the rigidity of the mountain retaining wall itself to suppress deformation. A method that has been often performed conventionally is a method of using a reinforced concrete underground continuous wall having a large wall thickness as a retaining wall, and using a strong supporting structure having high rigidity.

[0004]

However, the conventional construction method as described above also has the following problems. (1) It is costly to construct a reinforced concrete underground continuous wall having a large wall thickness at a large depth. (2) From the displacement example of the retaining wall shown in Fig. 9, considering the external force acting on the retaining wall from the surrounding ground, it is reasonable to construct a reinforced concrete underground continuous wall having the same wall thickness in the depth direction. It cannot be said to be the target. However, it is technically very difficult to construct a reinforced concrete underground wall whose wall thickness is changed according to the external force acting. (3) If the supporting work is made to have a strong structure by increasing the number of steps of the beam and increasing the size of the member while leaving the reinforced concrete underground wall as it is, the construction of the supporting work also costs much. Also, in large-scale cutting work, the supporting work itself hinders the work. Furthermore, much effort is required when disassembling.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mountain retaining method which is simple in construction and can be constructed at low cost.

[0006]

[0007]

In the present invention, the above
The following measures are taken to solve the problem of
It The earth retaining method according to claim 1 constructs a mountain retaining wall composed of a column-type underground continuous wall along a construction area of an underground structure in the ground, and a horizontal earth retaining wall is formed in the ground inside the construction area. Along the extending direction of the direction, a plurality of support walls made of improved bodies by the deep-layer mixing processing method are arranged at intervals, and then the building area is excavated and the mountain retaining wall exposed on the building area side is supported by the support work. It is characterized by doing.

The mountain retaining method according to claim 2 is the method according to claim 1.
The mountain retaining wall in the mountain retaining method described in (3) is characterized in that the mountain retaining wall has a double structure by additionally providing an auxiliary wall consisting of a column-type underground continuous wall or an improved body by the deep layer mixing treatment method.

[0009] Retaining method according to claim 3, claim 1
Alternatively, an inner wall made of an improved body formed by the deep layer mixing treatment method is arranged in parallel with the mountain retaining wall on the supporting wall in the mountain retaining method described in 2 .

[0010]

[0011]

According to the earth retaining method according to claim 1 , the support walls are arranged in parallel in a comb shape at intervals along the mountain retaining wall, whereby the mountain retaining wall and the supporting wall and the underlying ground soil existing therebetween. And are integrated into one structure. Since this structure becomes a mountain retaining wall having a large wall thickness and the cross-sectional rigidity is enhanced, the surrounding ground can be supported without being deformed or collapsed even by the lateral pressure applied from the surrounding ground.

According to earth retaining method according to claim 2, it is arranged in the support wall spaced upon which features an inner auxiliary wall of earth retaining wall in earth retaining method according to claim 1 in a comb-like Thereby, the cross-sectional rigidity of the mountain retaining wall can be further increased.

According to earth retaining method according to claim 3, by providing the support wall on the earth retaining wall and parallel to the inner wall in a box shape in earth retaining method according to claim 1 or 2, and earth retaining wall and the inner wall , In the meantime, the integration with the ground soil can be further strengthened.

[0014]

EXAMPLE A reference example of the mountain retaining method of the present invention will be described with reference to FIG. FIG. 1 shows a mountain retaining wall constructed by the mountain retaining method of this reference example. This clasp is on the ground J,
The earth retaining wall 10 which is a column-type underground continuous wall constructed along the construction area R of the underground structure, and the ground J outside the construction area R, the deep mixing constructed in parallel along the earth retaining wall 10. An outer wall 20 made of an improved body by the treatment method, an intermediate wall 30 made of an improved body by the deep layer mixing treatment method, which is constructed in a plurality so as to be hung between the mountain retaining wall 10 and the outer wall 20, and a building region R. It is configured by a support work 40 that supports the mountain retaining wall 10 exposed to the side.

Here, the deep layer mixing treatment method is one of the consolidation methods of the ground improvement method, and the stabilizers such as lime and cement are stirred with stirring blades on the ground where the wall is to be provided, and the soil is removed. It is a method of chemically solidifying. According to this deep layer mixing processing method, it is possible to construct a wall body in a certain area in the ground.

In order to construct the mountain retaining wall, first, a column-column type underground continuous wall having H steel as a core material is constructed along the construction region R of the ground J to form the mountain retaining wall 10. The lower end of the mountain retaining wall 10
It shall reach the supporting ground G such as underground rock.

Next, on the ground J outside the construction area R, the outer wall 20 is constructed in parallel along the mountain retaining wall 10. As a result, the construction region R is in a state of being surrounded by the double wall body.

Subsequently, a plurality of intermediate walls 30 are constructed on the ground J1 remaining between the mountain retaining wall 10 and the outer wall 20 with a space provided so as to be bridged between the mountain retaining wall 10 and the outer wall 20. As a result, around the building region R, a box-shaped wall body is built when viewed from above.

Here, the outer wall 20 and the intermediate wall 30 have an effective length in consideration of the deformation of the retaining wall 10 which is expected to be caused by the soil properties of the surrounding ground J and the earth pressure. Since the wall displacement of the mountain retaining wall 10 during the earth retaining excavation construction appears as shown in FIG. 9 described above, the lower ends of the outer wall 20 and the intermediate wall 30 are constructed deeper than the flooring surface T where the wall displacement is maximum.

Mountain retaining wall 10, outer wall 20 and intermediate wall 30
After the construction is completed, excavation on the construction region R side is started, and the exposed mountain retaining wall 10 is supported by disposing the supporting work 40.

If the earth retaining method as described above is adopted, by constructing the intermediate wall 30 between the earth retaining wall 10 and the outer wall 20, the earth retaining wall 10 and the outer wall 20 and the ground remaining between those wall bodies. The structure is integrated with J1. Considering this mountain retaining structure 50 as one wall, the mountain retaining wall 1
Since the vertical thickness of 0 increases, the rigidity of the mountain retaining structure 50 increases, the deformation of the mountain retaining wall 10 due to excavation is suppressed, and the ground J in the periphery is reliably supported.

Here, when only the mountain retaining wall is constructed,
The section modulus is compared with the case where the mountain retaining structure 50 is constructed by the above mountain retaining method. (A) Both of the mountain retaining wall 10 and the outer wall 20 have a thickness of 85c
When the mountain retaining structure 50 is constructed with the space between the intermediate walls 30 being 200 cm, the section modulus is: 78 times as large as the column-column underground continuous wall with a wall thickness of 85 cm. The reinforced concrete connecting wall with a wall thickness of 85 cm. It is 52 times that of the case where only the wall is constructed, 28 times that when only the reinforced concrete wall with a wall thickness of 100 cm is built, and 5 times that when only the reinforced concrete wall with a wall thickness of 150 cm is built. (B) Both the wall thickness of the mountain retaining wall 10 and the outer wall 20 is 85c
When the mountain retaining structure 50 is constructed with the space between the intermediate walls 30 being 100 cm, the section modulus is: 10 times as large as the column-column type underground continuous wall with a wall thickness of 85 cm. The reinforced concrete connecting wall with a wall thickness of 85 cm. It is 7 times the case where only the reinforced concrete joint wall is constructed, 3 times the case where only the reinforced concrete joint wall with a wall thickness of 100 cm is constructed, and 0.7 times the case where only the reinforced concrete joint wall with a wall thickness of 150 cm is constructed.

From the above comparison results, the mountain retaining structure 50 constructed by the mountain retaining method described in this embodiment can remarkably increase the sectional rigidity as compared with the conventional mountain retaining method.

Further, since the construction cost per unit area of the reinforced concrete connecting wall, which is symmetrical to the above comparison, is almost four times the construction cost per unit area of the column-column type underground continuous wall, for example, the wall thickness If a column-type underground continuous wall retaining structure 50 having a cross-sectional rigidity that is three times that of a 100 cm reinforced concrete connecting wall is constructed, the construction cost will be two minutes even if the retaining walls 10 and the outer wall 20 are made equal in depth. It is about 1. Therefore, the construction cost of the mountain retaining can be significantly reduced.

Further, since the rigidity required for the support work 40 can be reduced, the construction cost of the support work 40 can be reduced.

The space between the outer wall 20 and the intermediate wall 30 can be effectively used by constructing an underground passage, a parking lot, etc. after the structural body is completed in the construction area R part.

In this reference example, the outer wall 20 and the intermediate wall 30 were modified by the deep layer mixing method. The reason is that a large tensile stress acts on the mountain retaining wall 10 due to the influence of the soil quality and the earth pressure of the surrounding ground J, so that H steel is arranged to provide the stress, but the mountain retaining wall 10 and the outer wall 20.
Since there is a restrained ground J1 between the outer wall 20 and
This is because a large tensile stress does not act on. Therefore, depending on the design, the pillar-type underground continuous wall may be adopted as the outer wall 20.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 2 shows a mountain retaining wall constructed by the mountain retaining method of this embodiment. The mountain retaining wall is composed of a mountain retaining wall 110 composed of a column-type underground continuous wall constructed along the construction region R of the underground structure on the ground J, and a mountain retaining wall 11.
Auxiliary wall 111 made of an improved body constructed by the deep layer mixing processing method closely built inside 0 and the ground J inside the building area R are constructed in parallel along the horizontal extending direction of the mountain retaining wall 110. An inner wall 120 made of an improved body by the deep mixing processing method, and a support wall 130 made of a plurality of improved bodies by the deep mixing processing method that are constructed so as to be spanned between the mountain retaining wall 110 and the inner wall 120. , A support 140 supporting the mountain retaining wall 110 exposed on the side of the building region R
It consists of and.

In order to construct the mountain retaining wall, first, a pillar-line type underground continuous wall having H steel as a core material is constructed along the construction region R of the ground J to form the mountain retaining wall 110. It is assumed that the lower end of the mountain retaining wall 110 reaches the supporting ground G such as underground rock.

Next, on the ground J inside the building area R, the auxiliary wall 111 is built by the deep layer mixing processing method in which the ground wall J is closely contacted. It is assumed that the lower end of the auxiliary wall 111 reaches the same depth as the lower end of the mountain retaining wall 110, and the upper end of the auxiliary wall 111 is built up to the depth at which the flooring surface T is built.

Subsequently, the inner wall 120 is constructed on the ground J further inside the auxiliary wall 111 along the mountain retaining wall 110 in parallel by the deep layer mixing processing method. The lower end and the upper end of the inner wall 120 are constructed to the same depth as the auxiliary wall 111, respectively. As a result, the construction region R is in a state of being surrounded by the double wall body.

Further, the ground J2 remaining between the auxiliary wall 111 and the inner wall 120 is spaced so as to be bridged between the auxiliary wall 111 and the inner wall 120, and a plurality of support walls 130 are constructed by the deep layer mixing processing method. To do. As a result, the construction area R
Around the area, a wall body that is partitioned in a box shape is constructed when viewed from above.

Mountain retaining wall 110, auxiliary wall 111, inner wall 12
0 and the construction of the support wall 130 is completed, the construction region R
Start excavation on the side and support the exposed retaining wall 110
It is supported by disposing 40.

If the earth retaining method as described above is adopted, by constructing the support wall 130 between the auxiliary wall 111 and the inner wall 120, the ground remaining between the earth retaining wall 110 and the inner wall 120 and their wall bodies. It becomes a structure integrated with J2. If the mountain retaining structure 150 is regarded as one wall, the vertical thickness of the mountain retaining wall 110 increases, so that the rigidity of the mountain retaining structure 150 increases and the mountain retaining wall body accompanying excavation increases, as in the first embodiment. The deformation of 110 is suppressed and the surrounding ground J is reliably supported.

As shown in FIG. 3, the mountain retaining structure 150 is acted on by the main and receiving side pressures S, and the reaction force H acts on the bottom surface (in the direction of the arrow in the figure). However, the force L that attempts to rotate the mountain retaining structure 150 can be canceled by the reaction force H that acts on the bottom surface.

When the excavation proceeds, the earth retaining wall 110 is most deformed near the root cutting bottom (see FIG. 9), which causes the earth retaining structure 150 to have the earth retaining wall 11 as shown in FIG.
A shearing force F is generated between 0 and the auxiliary wall 111. However, by constructing the auxiliary wall 111 and the support wall 130,
The amount of deformation of the mountain retaining wall 110 can be reduced by canceling the generated shearing force.

Auxiliary wall 111, inner wall 120, support wall 130
As for the material of the improved body by the deep-layer mixing treatment method that composes, the maximum strain generated inside is 3% of the fracture strain obtained by the actual strength test as a result of the two-dimensional FEM analysis.
Since it is about one-third, the improved material itself can withstand deformation with a safety factor of about three times.

In this embodiment, the auxiliary wall 111
Although the improved body obtained by the deep-layer mixing processing method is adopted for the above, a column-row underground continuous wall may be adopted like the outer wall 110 depending on the design.

Further, depending on the design conditions, the auxiliary wall 11
1, one or both of the inner wall 120 is not constructed, and the mountain retaining structure 15 as shown in FIGS. 5 (A) and 5 (B).
It is also possible to construct 0a and 150b.

By the way, it is very important to measure the lateral pressure (earth pressure, water pressure, etc.) acting on the wall surface of the in-situ agitation system mountain retaining wall such as the column-row underground continuous wall described in the above embodiment. However, the conventional lateral pressure measurement in the in-situ stirring system earth retaining wall has the following problems. (1) Since the cross section of the in-situ stirring system earth retaining wall is circular, it is difficult to bring the earth pressure gauge into contact with the arc-shaped ground side surface. (2) In the in-situ stirring system earth retaining wall, the structural member with the earth pressure gauge is placed in the in-situ soil that has been stirred and mixed, and in order to jack the material with high density and viscosity, It's difficult to get close contact. (3) Earth pressure gauge The soil pressure gauge is sandwiched between the pressure receiving surface and the ground side surface, or the earth pressure gauge is pressed excessively against the ground side surface in order to avoid this, which causes indentation stress concentration. Very high pressure is often generated in the.

Therefore, if the following lateral pressure measuring method is adopted based on these problems, the lateral pressure acting on the wall surface can be accurately measured. First, as shown in FIG. 6, a mounting plate 61 having a shape that matches the shape of the cross section D of the in-situ stirring system mountain retaining wall is adopted on the pressure receiving surface of the earth pressure gauge 60. Provide multiple holes through which soil can pass. The jack 70 itself has the same shape capacity as the conventional one. As a result, the in-situ stirred soil passes through the holes provided in the mounting plate 61, and the mounting plate 61 comes into close contact with the cross section D of the ground.

FIG. 7 shows the measurement results obtained by the above lateral pressure measuring method. FIG. 7 shows the measurement results performed at two points on different plane positions. From this measurement result, the lateral pressure increases as the depth increases, and the magnitudes of the lateral pressures are almost the same, so it is considered that the lateral pressure measuring method is effective. Note that FIG. 7 also shows the measurement results by the existing measurement method, and from this measurement result, the influence of stress concentration is recognized such as showing a large lateral pressure value at a relatively shallow position.

[0043]

According to the mountain retaining method of the present invention, the mountain retaining structure is formed by integrating the wall bodies arranged at intervals and the ground existing between the wall bodies into one structure body. It is possible to effectively suppress the deformation of the mountain retaining wall due to the excavation of the construction area and the deformation of the surrounding ground. It is possible to dramatically increase the cross-sectional rigidity as compared with the conventional mountain retaining wall, and to significantly reduce the construction cost of the mountain retaining wall. Moreover, since the rigidity required for supporting work can be reduced by increasing the cross-sectional rigidity of the mountain retaining wall, the construction cost of supporting work can be reduced. Since earth retaining work is always performed in underground excavation work, designing and constructing using this earth retaining method will not only prevent deformation of the surrounding ground and reduce construction costs, but also the surrounding foundation including the completed structure. It is possible to effectively proceed with the maintenance and construction of incidental equipment.

[Brief description of drawings]

FIG. 1 is a sectional perspective view showing a reference example of a mountain retaining method of the present invention.

FIG. 2 is a cross-sectional perspective view showing an embodiment of the mountain retaining method of the present invention.

FIG. 3 is a cross-sectional view showing a state of an external force and a reaction force acting on the mountain retaining structure of the embodiment .

FIG. 4 is a cross-sectional view showing a state of shearing force acting on the mountain retaining structure of the embodiment .

5 is a cross-sectional perspective view showing another embodiment of the embodiment.

FIG. 6 is a plan view of an apparatus for performing a lateral ground lateral pressure measuring method.

FIG. 7 is a graph showing a lateral pressure value of a ground cross section measured by the lateral pressure measuring method.

FIG. 8 is a cross-sectional perspective view showing a conventional mountain retaining structure.

FIG. 9 is a graph showing an example of displacement of the retaining wall during excavation.

[Explanation of symbols]

10 mountain retaining wall 20 outer wall 30 Middle wall 40 support 110 Mountain retaining wall 111 auxiliary wall 120 inner wall 130 support wall 140 support work R construction area J ground G support ground

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 17/04 E02D 5/18 101-102 E02D 5/20 101-102

Claims (3)

(57) [Claims] 1. A ground retaining wall consisting of a column-type underground continuous wall is constructed in the ground along a construction area of an underground structure, and a horizontal extension direction of the mountain retaining wall is formed in the ground inside the construction area. A plurality of support walls made of the improved body by the deep layer mixing processing method are arranged at intervals along with, and then the construction area is excavated and the mountain retaining wall exposed to the construction area side is supported by the support work. Mountain retaining method. Inside of wherein earth retaining wall, according to claim, characterized in that the earth retaining wall features an auxiliary wall consisting of improved body by tubular elements formula underground continuous wall or Deep Mixing Method a double structure 1 Mountain retaining method described in. 3. An inner wall made of an improved body prepared by the deep-layer mixing processing method is arranged in parallel with a mountain retaining wall on a support wall made of an improved body wall made by the deep-layer mixed processing method, which is arranged at a plurality of intervals. The mountain retaining method according to claim 1 or 2 .