JP2019132095A - Box-shaped retaining wall - Google Patents

Abstract

To make it possible to store water temporarily under a box-shaped retaining wall in preparation for an unexpected amount of rainfall due to sudden rainfall or the like, and to prevent an outflow of and a decrease in stress intensity of a foundation ground so as to maintain the stability of a foundation ground and a back face ground.SOLUTION: A box-shaped retaining wall includes a plurality of steps z1, z2 piled up in a stairway shape along a sloping surface 10. In each of the steps z1, z2, a plurality of box-shaped retaining wall blocks 1 configured to include a surface plate 2, a rear counterfort plate 3 and connection plates 4, 4 connecting the surface plate 2 and the rear counterfort plate 3 are arranged laterally in front of the sloping surface 10. Each of the steps z1, z2 is constructed by filling void spaces 6, 7, 8 between the surface plate 2 and the sloping surface 10 with filling stones 19. A reservoir 14 extending laterally is provided under a box-shaped retaining wall block 1 in the lowermost step z1. The capacity of the reservoir per 1 m in lateral length is 0.4 to 4 m, water enters the reservoir from the top face part of the reservoir, and sediments in a surrounding ground 11 does not enter the reservoir substantially.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a box-type retaining wall.

  Retaining walls cannot be secured unless various conditions are met. In particular, ground bearing capacity, soil content of the back soil, drainage treatment function of intrusion water such as groundwater / surface water / rainfall, and earthquake resistance are important factors. Originally, the retaining wall has lost its function, collapsed, or deformed due to a destructive earthquake, or due to unexpected spring water, heavy rain, etc., a large amount of water infiltrates the back side of the retaining wall, thereby preventing the earth pressure function. Often lost. The present invention specifically addresses the latter water problem.

  When constructing a retaining wall, ground surface drainage (installation of gutters, pavements, drainage gradients, etc.) or retaining so that water (surface water on the surface, spring water from the back, rainfall, etc.) does not collect on the rear surface of the retaining wall It is fundamental to conduct drainage planning, such as providing a drainage layer (gravel layer, permeable mat, etc.) on the back of the wall.

  In the case of a rigid retaining wall such as an L-shaped retaining wall, in order to drain the water accumulated on the back surface, a countermeasure such as providing a drain hole on the wall surface and draining it to the front surface is common.

  As shown in FIG. 11, the box-type retaining wall described in Patent Document 1 excavates a groove 62 in the ground 61 before the slope 60, and a coarse granular foundation stone material 67 such as single-grain crushed stone is formed in the groove 62. A box-type retaining wall block having a base 64 provided with a geogrid 65 and including a surface plate 52, a holding plate 53, and two connecting plates 54, 54 connecting the base plate 52 and the base plate 64. A plurality of 51 are arranged, and a space from the surface plate 52 to the slope 60 is filled with a coarse-grained filling stone material 69 such as single-grain crushed stone to form one stage, and this stage is divided into a plurality of stages from the bottom to the top. And it is built up in a staircase shape.

  Since the box-type retaining wall has a gap between the filling stones 69, the drainage performance is very high as compared with the rigid retaining wall. Normally, the drainage is made up of the box-type retaining wall block 51 main body, residual water and groundwater. In order to remove the water, it is drained by a partially opened underdrain drainage pipe 68 embedded in the foundation 64. Even in this normal drainage plan, there has never been a collapse or deformation in the past due to heavy rain or sudden spring water (rapid increase in water).

Japanese Patent No. 3823075

  Recently, torrential rain (guerrilla heavy rain) due to abnormal weather has occurred frequently, and unexpected rainfall has occurred in a short time.

  In rigid retaining walls such as L-shaped retaining walls, water exceeding the drainage performance that was considered at the time of design due to guerrilla heavy rain invades the back of the retaining wall, the drainage is not in time, the foundation becomes soft, or the water pressure increases. There are cases where the retaining wall structure collapses due to loss of stability.

  As mentioned above, even with a box-type retaining wall with excellent drainage performance, it becomes difficult to drain the water that has entered the back of the retaining wall due to guerrilla heavy rain and increased in a short time with a normal partially opened underdrain drainage pipe. It cannot be said that the stability of the box-type retaining wall is not impaired. In particular, when building on the top of a slope (a large amount of rainwater may flow like a river on a road above the slope), the retaining wall is supported by a large amount of water that has entered the inside of the box-type retaining wall. There is a possibility that the stress level of the ground will decrease and the box-type retaining wall will be deformed.

  Therefore, when constructing in places where there is a high possibility of flooding in a short time due to guerrilla heavy rain, places such as mountainous areas where the amount of rainfall is considerably larger than flat land, places of water collecting terrain such as valleys, upper parts of slopes, etc. It is necessary to further enhance the drainage function of the box-type retaining wall.

  In addition, in places where drainage treatment seems to be sufficiently possible with ordinary partially open culvert drainage pipes, the necessity of implementation of the present invention may be low, but since recent guerrilla heavy rains can occur regardless of location, There has never been a further increase in the drainage function of the box-type retaining wall.

  Therefore, the present invention is designed to be able to temporarily store rainwater and spring water under the box-type retaining wall in preparation for unexpected rainfall due to guerrilla heavy rain, etc. The purpose is to maintain the stability of the ground and back ground.

The box-type retaining wall of the present invention is
It includes a plurality of steps stacked in a staircase pattern along the slope, and each step connects the surface plate that stands up with the plate that stands up behind it and the surface plate and the left and right intermediate portions of the plate. Box-type retaining wall blocks that include a plate are arranged in the left and right in front of the slope, and the space between the face plate and the slope is filled with a filling stone and built In the retaining wall,
Under the lowermost box-type retaining wall block, it extends to the left and right, and the water storage capacity per 1 m of left and right is 0.4 to ⁴ m3. Water enters the water tank from the upper surface of the water tank, and the surrounding ground It is characterized in that a water storage tank is provided in which no earth or sand substantially enters the water storage tank.

Although it does not specifically limit as a water tank, The following aspects (1) and (2) can be illustrated.
(1) The water storage tank includes a bowl-shaped geogrid, a suction prevention material affixed to the inner surface and inner bottom surface of the geogrid, and a foundation stone filled inside the suction prevention material. The aspect which stores water in the space | gap part between.

  It is preferable that the ground below the water storage tank of this aspect is a solidified ground in which earth and sand are semi-concrete with a cement-based solidifying material.

  It is preferable that a partial opening underdrain drainage pipe is embedded in the basic stone material of the water storage tank of this aspect.

  When the water storage tank of this aspect is constructed on the upper part of the slope, it is preferable that the outer surface of the wall surface and the bottom surface of the water storage tank is covered with a water shielding sheet.

  Moreover, it is preferable that the underdrain drainage pipe opened to the slope is connected to the partially opened underdrain drainage pipe buried in the foundation stone.

(2) A mode in which the water storage tank is a box made of precast concrete, and a water permeable hole is provided on an upper surface portion thereof.

  It is preferable that the foundation which surrounds a foundation stone material with a geogrid is provided on the upper surface part of the box made from precast concrete of this aspect and under the lowermost box-type retaining wall block.

  It is preferable that a submersible pump for draining to a predetermined drainage site outside the water tank is installed in the water tank.

  It is preferable that a water level confirmation pipe that extends vertically from the bottom of the water storage tank to the ground is provided.

  According to the present invention, even if an unexpected amount of rainfall occurs due to guerrilla heavy rain or the like in a short period of time, by temporarily storing a predetermined amount or more of rainwater or spring water under the box-shaped retaining wall, the outflow of the foundation ground In addition, the stress level can be prevented from being lowered, and the stability of the foundation ground and the back ground can be maintained.

FIG. 1 is a perspective view of a retaining wall according to the first embodiment. FIG. 2 shows a box-type retaining wall block used for the retaining wall, wherein (a) is a perspective view seen from the front side, and (b) is a perspective view seen from the back side. FIG. 3 is a sectional view in the middle of constructing the retaining wall (excavation of a groove). FIG. 4 is a sectional view in the middle of forming the retaining wall (forming a water storage tank). FIG. 5 is a sectional view in the middle of constructing the retaining wall (constructing the lowest level). FIG. 6A is a side view of the partially open underdrainage pipe, and FIG. 6B is a partial perspective view of the upper surface of the water storage tank. FIG. 7 is a cross-sectional view of the retaining wall according to the second embodiment. FIG. 8 is a cross-sectional view of the retaining wall according to the third embodiment. FIG. 9 shows an end block used for the retaining wall, where (a) is a cross-sectional view and (b) is a bb cross-sectional view. 10A and 10B show a modification example of the intermediate block used for the retaining wall. FIG. 10A is a sectional view of Modification Example 1, and FIG. 10B is a sectional view of Modification Example 2. FIG. 11 is a cross-sectional view of a retaining wall according to Conventional Example 1.

1. The water storage capacity of the water storage tank The water storage capacity per 1 m of the left and right length of the water storage tank is 0.4 to ⁴ m ³ as described above, and preferably 0.5 to ² m ³ . This is because if it is less than 0.4 m ³ , the amount of stored water is insufficient when an unexpected amount of rain occurs in a short time due to guerrilla heavy rain and the like, and if it exceeds 4 m ³ , the water storage tank becomes unnecessarily excessive.

2. The water tank of the aspect (1) The water tank of the aspect (1) is configured such that water enters the water tank from the upper surface of the water tank by the mesh on the upper surface of the geogrid, and the surrounding ground The earth and sand are not allowed to enter the water tank substantially, and water is stored in the space between the basic stone materials. The actual volume ratio varies depending on the basic stone, and the porosity is 100-actual volume ratio (%). Therefore, the water storage capacity per 1 m of the left and right length of the water storage tank of the aspect (1) is calculated by multiplying the inner volume of the bowl-shaped geogrid by the porosity based on the actual volume ratio of the basic stone material.
Moreover, since the bowl-shaped geogrid restrains a foundation stone material, the water tank of aspect (1) functions also as a strong foundation.

(A) Geogrid The geogrid preferably has a saddle shape including at least a bottom surface portion, front and rear wall surface portions, and a top surface portion, and further has a hexahedral shape including left and right end wall surface portions. It is preferable that the upper surface portion can be opened in a lid shape with respect to the wall surface portion (before filling the basic stone material) and is joined so as not to open again when closed (after filling the basic stone material).
The geogrid is not particularly limited, but a geogrid having a mesh unit that is smaller than the average particle size of the base stone and that allows a part of the base stone to protrude is preferable. This is because the basic stone can mesh with the lowermost filling stone.

(B) Suction prevention material Suction prevention material is provided with a filter function that allows water to pass through but does not substantially pass ground soil. Those that do not allow fine particles (silt, clay) having a particle size of less than 0.075 mm to pass through are preferred, but there is no particular problem even if they pass through.
Although it does not specifically limit as a sucking-out prevention material, A nonwoven fabric etc. can be illustrated.
It is preferable that the suck-out preventing material is attached at least to the inside of the front wall surface portion and the rear wall surface portion of the geogrid, and is further attached to the inside of the bottom surface portion of the geogrid. The anti-suction material does not have to be attached to the inside of the top surface of the geogrid, but it is attached to the inside of the top surface of the geogrid that protrudes before or after the lowermost box-type retaining wall block. It may be done.

(C) Foundation stone material Although it does not specifically limit as a foundation stone material, A crushed stone, a chestnut stone, etc. can be illustrated and a single grain crushed stone is preferable. As described above, the actual volume ratio differs depending on the basic stone material. For example, the actual volume ratio of No. 3 single grain crushed stone (S-40) is about 60%.

(D) Water-impervious sheet The material of the water-impervious sheet is not particularly limited, and examples thereof include rubber, felt, vinyl chloride, bentonite, and polyethylene.
The water-impervious sheet is preferably formed in a water tank shape by being adhered with an adhesive or a melting material depending on the material so as to cover the outside of the wall surface and the bottom surface of the water tank in a watertight manner.

3. Water tank of aspect (2) The precast concrete box of aspect (2) is designed to allow water to enter the water tank from the upper surface of the water tank through the water-permeable holes provided on the upper surface. The earth and sand of the ground are prevented from entering the water tank substantially. Moreover, the water tank of aspect (2) functions also as a firm foundation with the intensity | strength of the box made from a precast concrete.

  The precast concrete box of the aspect (2) preferably has a box shape including a bottom surface portion, front and rear wall surface portions, left and right end wall surface portions, and an upper surface portion.

  Next, embodiments of the present invention will be described with reference to the drawings. In addition, the structure of an Example and the shape dimension of each part are illustrations, and can be suitably changed in the range which does not deviate from the meaning of invention.

[Example 1]
The retaining wall of the first embodiment shown in FIGS. 1 to 6 is a box-shaped retaining wall having a plurality of steps z1 and z2 stacked stepwise along the slope 10 and a lowest step z1 as shown in FIG. It consists of a water storage tank 14 provided under the wall block 1.

  First, the plurality of stages z1 and z2 will be described. In each of the steps z1 and z2, a plurality of box-type retaining wall blocks 1 are arranged on the left and right before the slope 10, and filling stones 19 are provided in the spaces 6, 7, and 8 between the surface plate 2 and the slope 10. Is built by being filled.

  As shown in FIG. 2, the box-type retaining wall block 1 includes an upstanding surface plate 2, a holding plate 3 that stands up away from the surface plate 2, a middle portion in the left-right direction of the surface plate 2, and a holding plate A pair of connecting plates 4 and 4 that connect the three middle portions in the left and right direction are integrally precast with concrete.

  The surface plate 2 is a rectangular plate having a left and right length of about 2000 mm, a height of about 1000 mm, and a thickness of about 120 mm. The surface is provided with patterns such as stone wall patterns, groove patterns, etc. A shallow recess 5 for forming a drain slit is formed in the lower part. The holding plate 3 is a rectangular plate having a left and right length of about 1860 mm, a height of about 500 mm, and a thickness of about 120 mm. Each of the pair of connecting plates 4 and 4 has a front and rear length of about 1010 mm and a height of about 500 mm (however, only the front portion coupled to the surface plate 2 is a reinforcing portion increased to a height of about 900 mm), thickness It is a plate of about 100 mm. The weight of the box-type retaining wall block 1 is about 1300 kg.

  The lower end surfaces of the holding plate 3 and the connecting plates 4 and 4 are adjusted to the same level as the lower end surface of the surface plate 2. The connecting plates 4 and 4 are opposed to each other in parallel at an interval of about 1000 mm on the left and right, and the center position, the center position in the left and right direction of the surface plate 2 and the center position in the left and right direction of the holding plate 3 are matched to the front and rear. It has been. Therefore, with respect to the outer surface of each connecting plate 4, 4, the surface plate 2 protrudes about 400 mm to the near side end surface, and the holding plate 3 protrudes about 330 mm to the near side end surface. A flat square central space 6 surrounded by the surface plate 2, the holding plate 3, and the pair of connecting plates 4, 4 is provided. A planar U-shaped side recess 7 surrounded by the protruding portion of the surface plate 2, the protruding portion of the holding plate 3, and the connecting plates 4, 4 is provided. Further, a rear space 8 is formed between the holding plate 3 and the slope 10. As described above, the filling stone material 19 is filled in the voids 6, 7, and 8.

  Next, the water tank 14 will be described. The soil having a thickness of about 200 to 400 mm at the bottom of the groove 12 excavated in the ground 11 before the slope 10 becomes a solidified ground 13 semi-concrete with cement-based solidified material. In the groove 12 and on the solidified ground 13, a water storage tank 14 extending left and right is provided. Above the water storage tank 14, the box-type retaining wall block 1 at the lowest level z 1 is installed with a depth of 500 mm or more, and a part of the excavated soil surrounds the water storage tank 14 and the box-type retaining wall block 1. It is backfilled to become the backfill ground 11a.

  The water storage tank 14 includes a bowl-shaped geogrid 15, a suction prevention material 16 attached to the inside of the geogrid 15, and a basic stone material 17 filled inside the suction prevention material 16.

  The geogrid 15 is made of, for example, a high-density polyethylene resin, and has a mesh unit having a size smaller than the average particle diameter of the foundation stone material 17 and a part of the foundation stone material 17 that can be projected as shown in FIG. What you have is used.

  The geogrid 15 has a six-sided saddle shape including a bottom surface portion, front and rear wall surface portions, left and right end wall surface portions (not shown), and a top surface portion. The upper surface portion can be opened like a lid with respect to the wall surface portion (before filling the base stone material), and is joined so as not to open again when closed (after filling the base stone material). The distance between the front wall surface part and the rear wall surface part is 2050 mm, the distance between the bottom surface part and the upper surface part is 1400 mm, and the left and right lengths correspond to the site by arranging commercially available geogrids of predetermined dimensions while overlapping their end parts. And is of any length.

  The suck-out preventing member 16 is made of a continuous continuous fiber non-woven fabric of synthetic fibers, and is continuously attached to the inside of the bottom surface portion of the geogrid 15 and the front and back wall portions. The suction preventing member 16 is not attached to the inside of the upper surface portion of the geogrid 15 in this embodiment, but the portion of the upper surface portion of the geogrid that protrudes before or after the box-type retaining wall block 1 at the lowest level z1. It may be affixed inside.

  No. 3 single grain crushed stone (S-40) is used for the basic stone material 17. As described above, the actual volume ratio of No. 3 single-grain crushed stone (S-40) is about 60%, and therefore the porosity of single-grain crushed stone is about 40%.

  A partially opened underdrain drainage pipe 18 extending in the left-right direction is embedded in the lower rear side of the base stone material 17. As shown in FIG. 6 (a), the partially opened underdrain drain pipe 18 is made of resin (for example, SD-150A) having a reinforcing spiral convex portion 18a and a partially opened (hole) 18b. Yes.

  The water storage tank 14 configured as described above is configured such that water enters the water storage tank from the upper surface portion of the water storage tank by the mesh of the upper surface portion of the geogrid 15. Sediment is prevented from entering the water tank substantially, and water is stored in the space between the foundation stones. Moreover, since the bowl-shaped geogrid 15 restrains the foundation stone material 17, the water storage tank 14 functions also as a firm foundation.

The internal dimensions of the water storage tank 14 are almost determined by a distance of 1400 mm between the bottom surface and the top surface of the geogrid 15 and a distance of 2050 mm between the front wall surface portion and the rear wall surface portion. Since the porosity of S-40) is about 40%, the water storage capacity per 1 m of the left and right length of the water storage tank 14 is 1.15 m ³ (= 2.05 m × 1.4 m × 1 m × 40%). .

The retaining wall shown above is constructed as follows.
(1) As shown in FIG. 3, in the ground 11 before the slope 10, the front and rear groove width is larger than the front and rear length (1250 mm) of the box-type retaining wall block 1, and the groove depth is the height of the water storage tank 14. A groove 12 that is larger than the depth of the root is drilled.
(2) As shown in the figure, the soil at the bottom of the groove 12 is mixed with a cement-based solidifying material, stirred, and solidified to form a solidified ground 13.
(3) As shown in FIG. 4, the geogrid 15 is assembled in a bowl shape on the solidified ground 13, except that the upper surface portion of the geogrid 15 is separated from the mating end portions with respect to the front and rear wall portions. Keep it open.
(4) As shown in the figure, the sucking prevention member 16 is attached to the bottom surface, the front wall surface, and the rear wall surface of the geogrid 15.

(5) The base stone material 17 is put into the inside of the bowl-shaped geogrid 15 (the inside of the sucking prevention material 16) whose upper surface is opened, and rolling compaction is performed in a layered manner. The upper and lower mating ends of the upper and lower portions are closed and overlapped so as not to be opened again. The coupling is performed by, for example, bundling with a bundling member, heat welding, or the like. Thus, the water tank 14 is completed.
(6) As shown in FIG. 5, the box-type retaining wall block 1 is installed on the water storage tank 14 and the empty stones 6, 7, 8 are filled with the filling stone material 19 to construct the lowest stage z <b> 1.
(7) Thereafter, the second stage (z2) and higher steps are piled up stepwise along the slope 10 to complete the entire box-type retaining wall.

[Function and effect]
(A) Even if unexpected rains occur due to heavy rains such as guerrillas, temporarily store a certain amount or more of rainwater or spring water in the water storage tank 14 under the box-type retaining wall. It is possible to prevent the outflow and the decrease in the stress level and maintain the stability of the foundation ground and the back ground.
(B) After temporarily storing water, the ground 11 having good drainage, such as sandy soil, is drained by gradual natural penetration from the water storage tank 14 to the ground 11. Further, in the present embodiment, the water is also drained out of the water storage tank by the partially opened underdrain drainage pipe 18. Therefore, it does not store water for a long time.
(C) After temporarily storing water, even the ground 11 having a poor drainage property such as viscosity is gradually drained out of the water storage tank by the partially opened underdrain drainage pipe 18. If the drainage is slow, you can take measures such as installing a submersible pump in the reservoir and draining it to the nearest drain.

(D) Since the solidified ground 13 is semi-concrete with cement-based solidified material, it does not soften during the water storage.
(E) Since the earth and sand of the surrounding ground 11 does not substantially enter the water storage tank by the sucking prevention material 16, the voids of the foundation stone material 17 are not clogged and the water storage capacity is maintained. “Sediment does not substantially enter the storage tank” means that the clogging and deterioration of the storage capacity due to the use over time do not enter the problem, and therefore the earth and sand does not become a problem with the use over time. Is allowed to enter.
(F) In addition, as shown in FIG. 5, a water level confirmation pipe 9 extending vertically from the bottom of the water storage tank 14 to the ground can be provided. From the ground, a water level can be confirmed by inserting a stick into the water level confirmation pipe 9.

[Example 2]
The retaining wall of the second embodiment shown in FIG. 7 is installed on the upper surface of the slope 20 and is watertightly covered with the outer water shielding sheet 21 on the wall surface and the bottom surface of the water tank 14. It differs from the retaining wall of the first embodiment in that a culvert drainage pipe 22 that opens to the inclined surface 20 (no partial opening) is connected to the pipe 18, and the others are the same as the first embodiment.

According to the present embodiment, the same operational effects as (a), (c) to (f) of the first embodiment can be obtained, and the following operational effects (G) can be obtained.
(G) Since the water storage tank 14 is water-tightly covered with the water-impervious sheet 21, there is no possibility of sucking out the soil of the surrounding ground into the water storage tank 14, and therefore no depression due to the soil reduction of the surrounding ground is not caused. Even in such a case, the sucking prevention material 16 is installed in the water storage tank 14 to prevent invasion of earth and sand due to a breakage of the water shielding sheet or a construction failure.
(H) In addition, the drainage port of the underdrain drainage pipe 22 can be structured to protect the slope from being shaved by drainage.

[Example 3]
The retaining wall of Example 3 shown in FIG. 8 is constructed on a relatively soft ground 11, the water tank 14 is a precast concrete box 30, the formation of solidified ground is omitted, and the upper surface of the precast concrete box is It is different from the retaining wall of the first embodiment in that a foundation 41 formed by surrounding a coarse granular foundation stone 42 with a geogrid 43 is provided below the lowermost box-type retaining wall block 1. The others are the same as those in the first embodiment.

  The precast concrete box 30 is formed by connecting a plurality of intermediate blocks 31 shown in FIG. 8 and left and right end blocks 32 shown in FIG. And a six-sided box consisting of left and right end face parts and an upper face part.

The intermediate block 31 shown in FIG. 8 is made of reinforced concrete, has a rectangular tube shape including a bottom surface portion, front and rear wall surfaces, and a top surface portion, and has convex portions that restrict the position of the foundation 41 at front and rear end portions of the top surface portion. A portion 33 is provided, and a water permeable hole 34 is provided through an intermediate portion of the upper surface portion. The front-rear width and the left-right length of the intermediate block 31 are both 2300 mm. The internal dimensions are 1800 mm in the front and back, 550 mm in the front and back, and 700 mm in the center (average 625 mm), so the water storage capacity per 1 m of the left and right length of the water tank 14 is 1.13 m ³ (= 1.8 m × 0.625 m × 1 m).

  The end block 32 shown in FIG. 9 is made of reinforced concrete and has a one-end-closed rectangular tube shape including a bottom surface portion, front and rear wall surfaces, one end surface portion, and an upper surface portion. In addition to the hole 34, a manhole hole 35 is provided therethrough, and a submersible pump pit 36 is provided in the bottom surface portion. The submersible pump pit 36 is provided with a submersible pump 37 for draining to a predetermined drainage site outside the water storage tank.

According to the present embodiment, the same operational effects as (a), (c) to (f) of the first embodiment can be obtained, and the following operational effects (ku) can be obtained.
(H) When the soil that constructs the retaining wall is relatively soft, for example, a place where slope soil has collapsed and accumulated over the years, a place that has been formed by embankment in the past, etc. In the case of construction, in the water storage tank using the geogrid as in the first embodiment, after temporarily retaining water, the surrounding ground may be weakened due to the penetration of water to the surroundings, and the stability may be lost. In such a place, a precast concrete box 30 is installed to store water so that the strength of surrounding soil is not reduced. In addition, it increases the substantial penetration of the retaining wall and has the effect of increasing the stability of the entire retaining wall.

In the first modification of the intermediate block 31 shown in FIG. 10, the upper and lower dimensions of the internal dimension are fixed at 600 mm.
In the second modification of the intermediate block 31 shown in FIG. 11, the upper and lower inner dimensions are fixed at 600 mm, and the bottom portion is formed separately from the front and rear wall portions and fitted.

z1 Bottom stage z2 Second stage 1 Box-type retaining wall block 2 Surface plate 3 Holding plate 4 Connecting plate 5 Recess 6 Central cavity 7 Side cavity 8 Back cavity 9 Water level confirmation pipe 10 Slope 11 Ground 11a Filling Return ground 12 Groove 13 Solidified ground 14 Reservoir 15 Geogrid 16 Suction prevention material 17 Foundation stone 18 Partially open culvert drain pipe 18a Reinforcing spiral projection 18b Partially open (hole)
DESCRIPTION OF SYMBOLS 19 Filling stone material 20 Slope 21 Impervious sheet 22 Underdrain drainage pipe 30 Precast concrete box 31 Intermediate block 32 End block 33 Convex part 34 Permeation hole 35 Manhole hole 36 Submersible pump pit 37 Underwater pump 41 Foundation 42 Foundation stone material 43 Geo grid

Claims (10)

It includes a plurality of steps (z1, z2) stacked stepwise along the slope (10), and each step (z1, z2) stands upright apart from the standing surface plate (2). A box-type retaining wall block (1) including a retaining plate (3), a surface plate (2), and a connecting plate (4, 4) for connecting the left and right intermediate portions of the retaining plate (3) is a slope ( It is constructed in such a way that a plurality of stones are arranged on the left and right before 10) and the filling stone (19) is filled in the space (6, 7, 8) between the surface plate (2) and the slope (10). In the box-type retaining wall,
Under the bottom-stage (z1) box-type retaining wall block (1), it extends to the left and right and has a water storage capacity of 0.4 to 4 m ³ per meter of left and right length. A box-type retaining wall provided with a water storage tank (14) into which water enters and the earth and sand of the surrounding ground (11) does not substantially enter the water storage tank.   The water storage tank (14) fills the inside of the bowl-shaped geogrid (15), the suction prevention material (16) attached to the inner surface and the inner bottom surface of the geogrid (15), and the suction prevention material (16). 2. The box-type retaining wall according to claim 1, wherein the water is stored in a gap between the foundation stones (17).   The box-type retaining wall according to claim 2, wherein the ground under the water storage tank (14) is a solidified ground (13) in which earth and sand are semi-concrete with a cement-based solidifying material.   The box-type retaining wall according to claim 2 or 3, wherein a partial opening underdrainage pipe (18) is embedded in the basic stone material (17).   5. The water storage tank (14) is constructed on an upper part of the slope (20), and the outer surface of the wall surface and the bottom surface of the water storage tank (14) is covered with a water shielding sheet (21). Box-type retaining wall.   The box-type retaining wall according to claim 5, wherein a culvert drainage pipe (22) that opens to a slope (20) is connected to a partially open culvert drainage pipe (18) embedded in the foundation stone (17).   The box-type retaining wall according to claim 1, wherein the water storage tank (14) is a precast concrete box (30), and a water permeable hole (34) is provided on an upper surface portion thereof.   A base stone (42) is surrounded by a geogrid (43) on the upper surface of the precast concrete box (30) and under the box-type retaining wall block (1) at the lowest level (z1). The box-type retaining wall according to claim 7, wherein a foundation (41) is provided.   The box-type support according to any one of claims 1 to 8, wherein a submersible pump (37) for draining to a predetermined drainage site outside the water tank (14) is installed in the water tank (14). wall.   The box-type retaining wall according to any one of claims 1 to 8, wherein a water level confirmation pipe (9) extending vertically from the bottom of the water storage tank (14) to the ground is provided.

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