JP5930580B2 - Earth retaining wall and method of constructing earth retaining wall - Google Patents

Description

  The present invention relates to a retaining wall and a method for constructing a retaining wall.

  Conventionally, when a water barrier function is required for the earth retaining wall, the earth retaining wall of the ground improvement body constructed by mixing and stirring the original ground and cement milk is adopted, and the water shielding function is not required The earth retaining wall constructed by the main pile side sheet pile method is adopted. That is, depending on whether or not a water barrier function is required as a retaining wall, it is necessary to select either, so even if there is a soil layer that requires a water barrier function on a part of the excavation surface, It was necessary to adopt earth retaining walls for ground improvement over the entire excavation surface. This has led to an increase in construction costs.

  Then, the earth retaining wall of the parent pile horizontal sheet pile method which provides a water-impervious part only in the part for which a water-impervious function is required has been proposed (Patent Document 1).

As shown in FIG. 5, the retaining wall 70 of the parent pile lateral sheet pile method described in Patent Document 1 is installed between the parent pile 73 placed in the ground 72 at a predetermined interval and the parent pile 73. There is a water shielding portion 75 that blocks the flow of groundwater at the position of the aquifers 76 and 78 that need to be shielded and exist between the soil layers 77 that do not need to be shielded from the ground 72. Is formed.

Here, the water-impervious portion 75 is provided in the ground outside the retaining wall 70 and ranges from a slightly upper part of the upper surface of the aquifers 76 and 78 to a slightly lower part of the lower surface of the aquifers 76 and 78. It is formed by pressing a gel-like water shielding material into the ground.
However, the earth retaining wall described in Patent Document 1 has problems such as a decrease in water-blocking performance due to groundwater wrapping and an increase in construction process due to press-fitting of a gel-like water-blocking material.

JP 2009-68203 A

  An object of this invention is to provide the earth retaining wall which can give a water-blocking function only to the part, when there exists a soil layer which needs water-blocking in an excavation surface in view of the said fact.

The earth retaining wall according to the invention of claim 1 is provided with an excavation hole around the excavation part including a soil layer that needs water shielding without wrapping the outer peripheral part. It is provided in a part where the outer piles of the main piles built in all and the enlarged diameter parts provided in all the excavation hole portions located in the soil layer are wrapped and continuous, with cement milk and excavated soil. And a wall-shaped soil cement column impermeable portion.

According to the first aspect of the present invention, the soil cement column water shielding portion obtained by wrapping the outer peripheral portion of the expanded excavation hole with the outer peripheral portion of the adjacent excavation hole, To do. That is, it is possible to construct a water shielding wall having a water shielding function only on a soil layer that needs water shielding.
Thereby, even if there is a soil layer that requires a water shielding function on a part of the excavation surface, it is possible to provide a retaining wall of the parent pile lateral sheet pile method that can have a water shielding function only on that part.

  According to a second aspect of the present invention, in the earth retaining wall according to the first aspect, the excavation surface of the excavation part is between the parent piles except for a part where the soil cement column water-impervious part is constructed. It is characterized by a crossed sheet pile.

According to the invention described in claim 2, a soil cement column water-impervious portion having a water-impervious function is constructed only in the range of the soil layer that needs to be impermeable. There is a sheet pile between them.
Thereby, the part which does not need water-blocking can be constructed by the parent pile horizontal sheet pile method, and the construction cost can be reduced.

According to a third aspect of the present invention, in the earth retaining wall according to the first or second aspect, the parent pile is an H-shaped steel, and the excavation surface of the soil cement column water shielding portion is a flange of the H-shaped steel. It is characterized by being cut parallel to the surface.
According to the invention described in claim 3, the soil cement column water-impervious portion does not protrude toward the excavated ground side. That is, it is possible to provide a retaining wall that shields only a portion that needs water shielding without greatly changing the work contents of the main pile sheet pile method.

According to a fourth aspect of the present invention, there is provided a method for constructing a retaining wall, in which an outer peripheral portion is not wrapped around an excavation portion including a soil layer that needs water shielding, and a parent pile is formed to a predetermined depth. A step of excavating the excavation hole to be built, and mixing and stirring the cement milk and excavated soil while expanding the diameter of all the excavation holes, the outer peripheral portions is wrapped, the step of constructing a soil cement column water shielding portion surrounding the excavated portion, the before said cement milk soil cement column water shielding portion is solidified, all H-beam of the wellbore And a step of cutting the soil cement column water-impervious portion in parallel with the flange surface of the H-shaped steel while excavating the excavation portion.

  By using this method of building a retaining wall, even if there is a soil layer that requires a water shielding function on the excavation surface, only the soil layer can have a water shielding function. Can provide a retaining wall.

  Since this invention is set as the said structure, when there exists a soil layer which needs water shielding on an excavation surface, the earth retaining wall which can give a water shielding function only to the part can be provided.

It is a perspective view which shows the basic composition of the earth retaining wall which concerns on embodiment of this invention. It is the top view and side sectional drawing of the earth retaining wall which concern on embodiment of this invention. It is side surface sectional drawing which shows the construction procedure of the earth retaining wall which concerns on embodiment of this invention. It is the top view and side sectional view of an example of deployment of a retaining wall concerning an embodiment of the invention. It is a figure which shows the basic composition of the earth retaining wall of a prior art example.

  The retaining wall 10 according to the embodiment will be described with reference to FIGS. 1 is a perspective view, FIG. 2A is a plan view, FIG. 2B is a cross-sectional view of the ground, and FIG. 2C is a cross-sectional view of a retaining wall.

  The earth retaining wall 10 is constructed on the excavation surface 16 surrounding the excavation part of the ground. The earth retaining wall 10 is formed at a height H1 between the ground surface 42 and the excavation bottom surface 34 of the excavation part. A sandy soil layer 12 that needs water shielding is present on a part of the excavation surface 16, and the earth retaining wall 10 is required to have a water shielding performance.

  On the upper and lower portions of the sandy soil layer 12, viscous soil layers 14 and 15 are formed. The viscous soil layers 14 and 15 are layers that do not allow water to pass therethrough, and the water retaining performance is not required for the retaining wall 10. A sandy soil layer 13 further exists under the cohesive soil layer 15, but the depth H 1 of the retaining wall 10 extends to the viscous soil layer 15, and the sandy soil layer 13 directly affects the retaining wall 10. It does not affect.

The earth retaining wall 10 has an H-section steel 20, and the H-section steel 20 resists earth pressure from the back ground. The H-section steel 20 is built into a drilling hole 18 excavated by an auger head described later and solidified.
The excavation hole 18 has a cylindrical shape and is excavated with a diameter D1 to a depth H2 reaching the sandy soil layer 13. However, in the portion where the excavation hole 18 penetrates the sandy soil layer 12, the excavation diameter is expanded to the diameter D2.

Inside the excavation hole 18, a soil cement column 26 in which cement milk and excavation soil are mixed and stirred is constructed, and the H-section steel 20 built in the excavation hole 18 is solidified by the soil cement column 26.
At this time, the cylindrical portion expanded to the diameter D2 of the excavation hole 18 is wrapped around the adjacent outer peripheral portion, and the soil cement column water shielding portion 22 is constructed in a wall shape. Thereby, the sandy soil layer 12 can be closed with the earth retaining wall 10 and the water shielding function can be secured.

The upper ground excavation hole 28 of the soil cement column impermeable portion 22 is backfilled with the original ground (cohesive soil layer 14) as it is without discharging cement milk.
Here, the soil cement column impermeable portion 22 is constructed from a position deeper than the bottom surface of the sandy soil layer 13 by a depth H3, and further constructed to a position shallower than the top surface of the sandy soil layer 13 by a depth H4. Yes. Here, the depth H3 is preferably about 500 mm. Thereby, the water leak from an upper-lower-end part can be prevented.

  The excavation surface 16 is formed in a flat plate shape by cutting the excavation part side of the soil cement column impermeable part 22. That is, the soil cement column water-impervious portion 22 is cut in a direction parallel to the flange surface of the H-section steel 20 to a position where the flange surface is exposed. As a result, the soil cement column impermeable part 22 does not protrude to the excavation part side.

  In addition, a lateral sheet pile 24 is provided above the excavation surface 16, that is, on the soil cement column water shielding portion 22. The lateral sheet piles 24 are made of plywood, are stacked and bridged between the H-section steels 20, and receive the earth pressure of the viscous soil layer 14.

  As described above, the soil retaining wall 10 having a water shielding function can be obtained by constructing the soil cement column water shielding portion 22 by wrapping the outer peripheral portion in a range where the sandy soil layer 12 that needs water shielding is blocked. Can be provided. Further, for the viscous soil layers 14 and 15 that do not require water shielding, a soil retaining function is secured by bridging the cross sheet pile 24 between the H-section steel 20.

  Thereby, the earth retaining wall 10 of the parent pile horizontal sheet pile method which can insulate only the sandy soil layer 12 which needs water shielding can be provided, without changing the work content of the conventional parent pile horizontal sheet pile method greatly. As a result, the construction cost can be reduced.

In addition, although the soil layer which needs water shielding demonstrated the sandy soil layer 12 to the representative example, it is not limited to this, Even if it is another soil layer, it can shield. On the other hand, even if it is the sandy soil layer 12, when water shielding is unnecessary, naturally it is not necessary to give a water shielding function.
Moreover, in the range where the excavation surface 16 is the viscous soil layer 14, water shielding is unnecessary, and the cross sheet pile 24 is bridged between the H-section steels 20, but in the viscous soil layer 14 where there is no risk of collapse, The lateral sheet pile 24 may be omitted.

  Moreover, although the H-shaped steel 20 was demonstrated in the state built in all the excavation holes 18, it does not necessarily need to be constructed in all the excavation holes 18, but the density (number) according to the earth pressure from a back ground. Can be determined.

  The upper excavation hole 28 of the soil cement column impermeable portion 22 is filled with the original ground (viscous soil layer 14) as it is without discharging cement milk. You may build a column.

Next, the construction method of the earth retaining wall 10 will be described with reference to FIG.
First, the excavation process of an excavation hole shown in FIG. That is, the excavation rod 40 with the auger head 30 attached to the tip is set at the position of the excavation hole 18. The auger head 30 is rotated and the excavation hole 18 is excavated with the diameter D1 to the depth H2 while discharging the excavation water from the tip. The excavation hole 18 is formed by penetrating the sandy soil layer 12 that is a soil layer that needs water shielding in the vertical direction.

  Next, the construction process of the soil cement column water shielding part shown in FIG. 3 (B) is executed. That is, the auger head 30 is moved to the position of the sandy soil layer 12 (the range of the arrow H1), and the excavation hole 18 is subjected to diameter expansion excavation with the auger head 30.

  The auger head 30 is configured to be capable of expanding excavation by rotating in reverse. Specifically, the excavation direction in FIG. 3A is the forward rotation of the auger head 30, and the excavation hole 18 is excavated with the diameter D1. Subsequently, by rotating the auger head 30 in the reverse direction, the tip 31 of the folded auger head 30 expands, and the excavation hole 18 is expanded to a diameter D2 for excavation. Thereby, the outer peripheral part of the adjacent digging hole 22 expanded in diameter is overlapped with each other.

  Next, as shown in FIG. 3C, a soil cement column is constructed inside the excavation hole 18. That is, while the auger head 30 is returned to the normal rotation again and rotated, the excavated soil settled in the lower portion of the excavation hole 18 is excavated again to confirm the stability of the hole wall. Thereafter, the cement milk is discharged from the tip of the auger head 30 while rotating forward, and the cement milk and the excavated soil are mixed and stirred while being pulled up. After the cement milk is injected up to the position of the upper surface of the expanded excavation hole 18, the injection is finished and the excavation rod 40 is pulled out from the excavation hole 18.

  Next, the erection process of the H-section steel 20 shown in FIG. That is, before the cement milk is solidified, the H-section steel 20 is built and held in the excavation hole 18. Thereby, the H-section steel 20 is solidified by the soil cement column. Moreover, the soil cement column water-impervious portion 22 is constructed as a continuous column by solidifying the cement milk. Thereafter, the ground 14 is buried back in the upper portion 28 of the excavation hole 18.

  Finally, the cutting process shown in FIG. That is, the ground excavation part is excavated from the ground surface 42 to the excavation bottom surface 32. At this time, the horizontal sheet pile 24 is excavated while being bridged between the H-section steels 20 so that the viscous soil layer 14 does not collapse. Moreover, in the soil cement column water-impervious portion 22, the excavated portion side is cut out in parallel with the flange surface of the H-section steel to a position where the flange surface is exposed.

  By constructing the earth retaining wall 10 by the method described above, even if the sandy soil layer 12 requiring a water shielding function exists on the excavation surface 16, only the range of the sandy soil layer 12 is shielded. The earth retaining wall 10 can be provided.

  In addition, the example which used the auger head 30 provided with the function in which the diameter-expanded excavation hole 22 was reversely rotated and diameter expansion excavation was demonstrated was demonstrated. However, it is only necessary that the diameter of the excavation hole 18 can be increased, and the present invention is not limited to this. For example, a method may be used in which drilling water or cement milk is discharged as a jet flow in the lateral direction, the drill hole 18 is drilled in the horizontal direction with the jet flow discharge pressure, and the diameter is expanded.

Next, a development example will be described.
As shown in FIG. 4, the earth retaining wall 50 is constructed on the excavation surface 16 surrounding the excavation part of the ground. The earth retaining wall 50 is formed at a height H1 between the ground surface 42 and the excavation bottom surface 34 of the excavation part. Sandy soil layers 12 and 36 that need to be water-blocked exist in a part of the excavation surface 16, and the water-blocking performance is required for the earth retaining wall 10.

  A viscous soil layer 14 is formed above the sandy soil layer 36, and a viscous soil layer 38 is formed below the sandy soil layer 36. Further, a sandy soil layer 12 is formed under the viscous soil layer 38, and a viscous soil layer 15 is formed under the sandy soil layer 12. That is, two layers of sandy soil layers 12 and 36 exist on the excavation surface 16.

  Correspondingly, the soil cement column impermeable portion 52 of the earth retaining wall 50 is constructed from a position deeper than the bottom surface of the sandy soil layer 12 by a depth H3, and is further deeper than the upper surface of the sandy soil layer 36. It is built to a position shallower by H3. Here, the depth H3 is preferably about 500 mm.

As described above, when there are a plurality of sandy soil layers 12 and 36 in the vertical direction, the soil cement column water-impervious portion 52 is constructed so as to continuously cover the plurality of sandy soil layers 12 and 36. May be. Thereby, construction cost can be reduced.
Other configurations are the same as those in the above-described embodiment, and a description thereof will be omitted.

10 Earth retaining wall 12 Sandy soil layer (soil layer that needs water shielding)
16 Drilling surface 18 Drilling hole 20 H-section steel (parent pile)
22 Soil cement column

Claims (4)

Around the excavation part including the soil layer that needs water shielding, a drilling hole is provided without wrapping the outer peripheral part, and a parent pile built in all of the excavation hole,
A wall-shaped soil cement column formed of cement milk and excavated soil, which is provided in a continuous portion by wrapping the outer peripheral portions of the enlarged diameter portions provided in all the excavation hole portions located in the soil layer A water shielding part,
With earth retaining wall.   The earth retaining wall according to claim 1, wherein a lateral sheet pile is bridged between the parent piles on the excavation surface of the excavation part except for a portion where the soil cement column impermeable part is constructed.   The earth retaining wall according to claim 1 or 2, wherein the parent pile is an H-shaped steel, and an excavation surface of the soil cement column water shielding portion is cut in parallel with a flange surface of the H-shaped steel. Drilling a drilling hole to build a parent pile up to a predetermined depth, without wrapping the outer peripheral part around the excavation part including a soil layer that needs water shielding,
Constructed in the range of the soil layer, mixing and agitating cement milk and excavated soil while expanding all the excavation holes, wrapping the outer peripheral portions of the adjacent expanded excavation holes, A process for constructing a surrounding soil cement column water-impervious part;
Before the cement milk of the soil cement column impermeable part is solidified, a step of building H-shaped steel in all of the excavation holes;
Cutting the soil cement column impermeable part parallel to the flange surface of the H-shaped steel while excavating the excavation part;
A method for constructing a retaining wall.

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