JP2017119952A - Sheeting wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize improvement of workability and reduction of material cost while appropriately imparting rigidity required for a retaining wall main body in a retaining wall in which a steel frame core material is embedded in a cement-based retaining wall main body. Providing technology that can be used. SOLUTION: In a mountain retaining wall 1 in which a steel frame core material 3 is embedded in a cement-based retaining wall main body 1a, the steel frame core material 3 is biased to the outside on the back soil side in the wall thickness direction of the retaining wall main body 1a. Place it. [Selection diagram] Fig. 2

Description

  The present invention relates to a retaining wall in which a steel core material is embedded in a cement-based retaining wall body.

As a conventional retaining wall, for example, one using a ground improvement structure in which ground improvement is performed on an excavated ground is known (see, for example, Patent Document 1).
This ground improvement structure is a grid with a columnar improvement structure built by mixing and stirring cement-based solidified material in a soft excavated ground where liquefaction may occur during an earthquake. It is constructed by “TOFT method (registered trademark)” which is continuously arranged in a shape. And the retaining wall main body is comprised by extending the outer peripheral part of the lattice-like ground improvement structure upwards to the surface of a surrounding ground.

  In this mountain retaining wall main body, a steel core material is embedded in order to ensure the required rigidity. In addition, this steel frame core material is disposed with its side surface exposed inside to be excavated in the wall thickness direction of the retaining wall main body. And as a steel-frame core material embedded in a mountain retaining wall main body, the large H-section steel whose distance between the outer surfaces of a pair of flange in a cross section is about 2/3 with respect to the wall thickness of a mountain retaining wall is used.

JP 2012-112162 A

In the case of the retaining wall as described above, the workability is improved and the material cost is reduced by using a part of the ground improvement structure for the retaining wall. Improvements are desired.
In view of this situation, the main problem of the present invention is that in the retaining wall in which the steel core material is embedded in the cement-based retaining wall body, the workability is improved while appropriately providing the necessary rigidity to the retaining wall body. The object is to provide a technique capable of realizing a reduction in material cost.

The first characteristic configuration of the present invention is a retaining wall in which a steel core material is embedded in a cement-based retaining wall body,
In the wall thickness direction of the mountain retaining wall main body, the steel core material is arranged so as to be biased to the outside on the back soil side.

According to this configuration, the steel core material can be downsized while appropriately providing the necessary rigidity to the mountain retaining wall body by biasing the embedding position of the steel core material embedded in the mountain retaining wall body outward in the wall thickness direction. As a result, improvement in workability and reduction in material costs can be realized.
That is, in the retaining wall main body, in the state where the inner side is excavated while receiving earth pressure from the outer backside soil, the vertical tensile stress acts on the outer side and the vertical compressive stress acts on the inner side. On the other hand, since the steel retaining wall body is arranged with the steel core material biased to the outside, the outer tensile strength is reinforced. As a result, the tensile stress acting on the outside is suitably received by the steel core material mainly having high tensile strength, while the compressive stress acting on the inside is mainly cemented solidified after solidification mainly having high compressive strength. It can receive suitably with a material. Therefore, even when the steel core material is downsized, the necessary rigidity can be appropriately imparted to the retaining wall main body.

  The 2nd characteristic structure of this invention exists in the point by which the said steel-frame core material is arrange | positioned only at the up-and-down intermediate part of the said retaining wall main body.

According to this configuration, it is possible to further improve the workability and lower the material cost by further reducing the size of the steel core material while appropriately providing the necessary rigidity of the retaining wall body. .
That is, the vertical tensile stress acting on the outside of the retaining wall main body increases in the vertical direction in the portion of the excavation ground side that supports the falling down to the inner side of the retaining wall main body. Get smaller. Therefore, by arranging the steel core material only in the upper and lower intermediate parts including the part on the excavation ground side in the retaining wall main body, the tensile strength for withstanding the large tensile stress acting on the upper and lower intermediate parts is secured. On the other hand, since the arrangement of the steel core material is omitted in the vicinity of the upper end and the lower end where the tensile stress is small, the required length of the steel core can be reduced.

  For example, when a ground improvement structure in which ground improvement is performed on the excavated ground is constructed, and the mountain retaining wall body is configured by extending the outer peripheral side portion of the ground improvement structure upward, the mountain retaining body is The inside (excavated ground side) is supported by the ground improvement structure. As a result, the portion of the excavation ground side that supports the inward collapse of the retaining wall main body rises to the vicinity of the upper end of the inner ground improvement structure, that is, the vicinity of the surface of the excavation ground. Therefore, since the upper and lower range in which the arrangement of the steel core material can be omitted is increased on the lower end side of the mountain retaining wall main body, the required steel core material can be further shortened.

The third characteristic configuration of the present invention is a ground improvement structure in which ground improvement is performed on the excavation ground,
The said mountain retaining wall main body exists in the point comprised by extending the outer peripheral side site | part of the said ground improvement structure upwards.

  According to this configuration, the improved ground structure is used to extend the outer peripheral portion upward, and function as a retaining wall body that receives earth pressure from the outer back soil as a series of structures. There is no need to construct a retaining wall separate from the ground structure, and further improvement in workability and reduction in material costs can be achieved.

Plan view showing the improved ground structure built in the planned construction site and the built-up state of the mountain retaining wall using it Side sectional view showing the construction of the retaining wall Plan sectional view showing the construction of the retaining wall

Embodiments of the present invention will be described with reference to FIGS.
As shown in FIG. 2, around the excavation ground g ′, which is the planned construction site of the new building 60, the inner excavation part side (excavation) withstands the earth pressure from the back soil side constituting the outer peripheral ground g. A mountain retaining wall 1 comprising a mountain retaining wall main body 1a for preventing collapse of earth and sand to the ground g 'side) is constructed.
Further, the mountain retaining wall 1 is constructed by using a ground improvement structure 10 in which ground improvement is applied to the excavated ground g ′ as a countermeasure against the liquefaction phenomenon.
And on the ground improvement structure 10 inside this retaining wall 1, for example, a concrete retaining wall 30 and a foundation portion 40 are provided. In addition, a new building 60 is constructed on the foundation 40 with, for example, a seismic isolation device 50 interposed therebetween.

(Ground improvement structure)
First, the ground improvement structure 10 will be described below.
As shown in FIG. 1, the ground improvement structure 10 is a soft excavated ground in which column-arranged portions 10 a, 10 b, and 10 c are arranged in a lattice shape in a state where column-shaped improvement bodies are overlapped between adjacent ones. g ′ is enclosed in a lattice shape to suppress the occurrence of liquefaction during an earthquake. This columnar improvement body is constructed by mixing and stirring the cement-based solidified material with the soil at the current position while discharging cement-based solidified material such as cement milk into the ground.

  The shape of the ground improvement structure 10 in a plan view can be appropriately determined according to the new building 60 and the surrounding environment. In this embodiment, as shown in FIG. 1, the new building 60 (see FIG. 2) According to the outer shape, long sides and short sides are alternately arranged to form a lattice shape having a deformed hexagonal shape in which each inner angle is 120 °. That is, the ground improvement structure 10 includes an outer peripheral columnar part 10c arranged along the deformed hexagon and two types of first inner pillars arranged inside the outer peripheral columnar part 10c and intersecting each other. It is comprised by the row | line | column part 10a and the 2nd inner side pillar row | line | column part 10b.

  Specifically, the first inner columnar part 10a has an angle of 120 ° from the ground center part p1 that is the central part of the excavated ground g ′ surrounded by the outer peripheral columnar part 10c in plan view. Thus, it is configured as three columnar column portions extending radially. And the edge part on the opposite side to the ground center part p1 of each 1st inner side pillar row | line | column part 10a is to the connection part p4 which is the center part of the long side which comprises the said deformed hexagon of the outer peripheral side columnar row | line | column part 10c. It will be connected from the inside.

  On the other hand, the second inner columnar part 10b is configured as three columnar parts intersecting in a vertical direction with the columnar central part p2 that is near the center of each first inner columnar part 10a in plan view. ing. That is, these second inner columnar portions 10b are arranged in a triangle that intersects with each other at three intersecting portions p3 and surrounds the ground center portion p1. Furthermore, it extends outward from the intersection p3 that is the apex of the triangle, and each end is in the vicinity of the connecting portion between the long side and the short side that constitute the above-described hexagonal shape of the outer columnar part 10c. The connection part p5 is connected from the inside.

  By adopting the ground improvement structure 10 having such a configuration, the irregular hexagonal excavation ground g 'can be surrounded by the columnar row portions 10a, 10b, and 10c in a substantially uniform lattice shape. Thereby, generation | occurrence | production of the liquefaction phenomenon resulting from the shear failure of the excavation ground g 'at the time of an earthquake can be suppressed reasonably.

(Mountain retaining wall)
Next, the configuration of the retaining wall 1 will be described below.
As shown in FIGS. 1 and 2, the mountain retaining wall body 1 a constituting the mountain retaining wall 1 is configured using the ground improvement structure 10 described above in order to improve workability and reduce material costs. Yes. That is, as shown in FIG. 2, the outer peripheral side columnar part 10c which is the outer peripheral side part of the ground improvement structure 10 is extended to the surface of the upper peripheral ground g, and the extended outer peripheral columnar part 10c is a retaining wall. 1 functions as a retaining wall main body 1a.

  As shown in FIGS. 2 and 3, each columnar body constituting the retaining wall main body 1a is subjected to earth pressure from the outer side (left side in FIGS. 2 and 3) on the peripheral ground g side while receiving the earth pressure (FIG. 2). And the steel core material 3 is embedded so that it can stand by itself even when it is excavated. And the steel core material 3 embedded in the mountain retaining wall main body 1a in this way is arranged so as to be biased outward in the wall thickness direction of the mountain retaining wall main body 1a. Thus, the mountain retaining wall main body 1a is reinforced in the vertical tensile strength on the outside.

  Specifically, in this mountain retaining wall main body 1a, in a state where the inner side is excavated while receiving earth pressure from the outside, a vertical tensile stress acts on the outside, and a vertical compressive stress acts on the inside. And in the retaining wall main body 1a embedded with the steel core 3 biased outward, the outer tensile stress can be suitably received mainly by the steel core 3 having a high tensile strength, while the inner compressive stress is applied. It can be suitably received mainly by a cement-based solidified material having a high compressive strength after solidification. That is, in this mountain retaining wall main body 1a, the acting force on the mountain retaining wall main body 1a can be received in a well-balanced manner by the steel core material 3 and the cement-based solidifying material. Thereby, size reduction of the steel-frame core material 3 is achieved, ensuring required rigidity.

As the steel core material 3 embedded in the retaining wall main body 1a, for example, an H-section steel whose distance between the outer surfaces of a pair of flanges in the cross section is about 1/3 to 1/7 of the wall thickness of the retaining wall main body 1a is used. The steel core material 3 can be suitably used.
By downsizing the steel core material 3 in this manner, the workability when the steel core material 3 is embedded in the retaining wall main body 1a is improved, and further, the material cost of the steel core material 3 is reduced. It will be.

Moreover, in such a retaining wall main body 1a, the tensile stress increases toward the outside in the wall thickness direction. Therefore, the embedding position of the steel core material 3 in the wall thickness direction of the retaining wall main body 1a is set as outside as possible within a range in which a minimum thickness can be secured for the cement-based solidified material covering the steel core material 3. It is desirable.
For example, the deviation width D from the center portion of the retaining wall body 1a to the center portion of the steel core 3 in the wall thickness direction is the wall thickness of the retaining wall body 1a (the diameter of the columnar body constituting the retaining wall body 1a). It can be set to about 1/2 to 1/4.

  The vertical tensile stress acting on the outer side of the retaining wall main body 1a becomes larger at the site on the excavation ground g ′ side that can support the inward collapse of the retaining wall main body in the vertical direction, and the farther away from the site. Get smaller. Therefore, as shown in FIG. 2, the steel core material 3 is disposed only in the upper and lower intermediate portions of the retaining wall main body 1 a including the portion on the excavation ground g ′ side.

  That is, on the outside of the retaining wall main body 1a, the tensile stress in the vertical direction is large, so that the steel core 3 is present at the upper and lower intermediate portions where the tensile stress cannot be withstood by the cement solidified material alone. Strength is reinforced. On the other hand, since the tensile stress in the vertical direction is small, the steel core material 3 is shortened so that the steel core material 3 does not exist on the upper end side and the lower end side where sufficient strength can be obtained only with the cement-based solidified material. Is realized. Thus, the workability is further improved and the material cost is reduced by shortening the steel core 3 while maintaining the rigidity of the retaining wall main body 1a.

  Further, since the inside of the retaining wall main body 1a is supported by the inner columnar portions 10a and 10b of the ground improvement structure 10, the portion on the excavation ground g ′ side that supports the falling of the retaining wall main body 1a to the inner side is as follows. , Near the upper end of the inner ground improvement structure 10. Therefore, the steel core 3 embedded in the mountain retaining wall main body 1a is arranged in the vertical middle part including the vicinity of the upper end of the inner ground improvement structure 10 in the vertical direction. The upper and lower range in which the arrangement of the steel core 3 on the lower end side of 1a can be omitted is increased.

  In addition, in the retaining wall main body 1a in which the inside is excavated by receiving earth pressure from the outer peripheral ground g, a bending moment is generated on the upper side with reference to the vicinity of the upper end portion of the inner ground improvement structure 10, and the bending moment A vertical tensile stress is generated outside the predetermined vertical range near the upper end of the ground improvement structure 10. Therefore, the length of the upper side range La from the vicinity of the upper end of the inner ground improvement structure 10 to the upper end of the steel core 3 can be set in consideration of both the bending moment and the tensile stress generated thereby. On the other hand, the length of the lower side range Lb from the vicinity of the upper end of the ground improvement structure 10 of the steel core 3 to the lower end is preferably set in consideration of the tensile stress.

Among the plurality of columnar bodies constituting the retaining wall main body 1a, the columnar bodies to which the inner columnar portions 10a, 10b are directly connected include the upper and lower middles including the vicinity of the upper end portion of the inner ground improvement structure 10 as described above. If the steel core material 3 is disposed only at the site, sufficient rigidity can be obtained.
On the other hand, the columnar body in which the inner column row portions 10a and 10b are not connected and the soft excavation ground g ′ is present on the inner side is the same as the columnar body in which the inner column row portions 10a and 10b are directly connected. The steel core material 3 is disposed only at the upper and lower intermediate positions. As a result, the material cost of the steel core 3 is reduced as the entire retaining wall 1. As for the columnar bodies not connected to the inner columnar portions 10a, 10b, columnar bodies having sufficient rigidity that are directly connected to the inner columnar portions 10a, 10b are arranged on both sides, and the columnar bodies on both sides are arranged. Therefore, even when the steel core material 3 is arranged only at the upper and lower intermediate positions, the necessary rigidity can be obtained.

In the work of embedding the steel core material 3 in the retaining wall body 1a, the steel core material 3 is inserted downward from the upper end portion of the retaining wall body 1a before the cement-based solidified material is solidified. Further, in this embedding operation, when the cement-based solidified material in the insertion portion of the steel core material 3 is vibrated by a vibrator or the like, the resistance during the insertion is reduced, and the steel core material 3 can be inserted with its own weight.
If the operation and stop of the vibration by the vibrator are adjusted, the amount of insertion of the steel core material 3 can be easily adjusted. Can be placed.

[Another embodiment]
(1) In the above embodiment, the steel core material 3 is disposed only at the upper and lower intermediate portions of the retaining wall body 1a. However, the steel core material 3 is within a range in which the necessary rigidity of the retaining wall body 1a can be ensured. You may change the position in the up-down direction.

(2) In the above embodiment, the outer peripheral side columnar portion 10c of the ground improvement structure 10 is extended upward to form the mountain retaining wall main body 1a. However, the ground improvement structure 10 can be used without using the ground improvement structure 10. You may comprise so that another mountain retaining wall main body 1a may be constructed | assembled outside.

DESCRIPTION OF SYMBOLS 1 Mountain retaining wall 1a Mountain retaining wall main body 3 Steel core material 10 Ground improvement structure 10c Outer peripheral side columnar row part (outer peripheral side part)
g Surrounding ground g 'Drilling ground

Claims (3)

A retaining wall in which a steel core material is embedded in the cement retaining wall body,
A mountain retaining wall in which the steel core material is arranged so as to be biased toward the outside on the back soil side in the wall thickness direction of the mountain retaining wall main body.   The mountain retaining wall according to claim 1, wherein the steel core material is disposed only at an upper and lower intermediate portion of the mountain retaining wall main body. A ground improvement structure was constructed by applying ground improvement to the excavated ground,
The mountain retaining wall according to claim 1 or 2, wherein the mountain retaining wall main body is configured by extending an outer peripheral side portion of the ground improvement structure upward.

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