JPH08311864A - Earth retaining wall and construction method therefor - Google Patents

Abstract

PURPOSE: To provide an earth retaining wall having high rigidity and cut-off performance by a compact-sized construction machine by forming a peristyle-like continuous wall with a stress bearing pile material erected along the outer periphery of the ground drilling range and a high pressure injection and stirring pile which comes into close contact with the pile material. CONSTITUTION: After mud is circulated to bore a hole, H-shaped steel piles 11 are erected as a stress bearing pile material at spaces P along the outer periphery of the foundation part 1. The space P and size are set in such a manner that a member stress to the maximum earth pressure generated in the drilling stage is an allowable unit stress or less. After the completion of erection, a high pressure injection and stirring pile is established between the H-shaped steel piles 11 to form an earth retaining wail 10. The range surrounded with the wall 10 is divided into several drilling steps, and drilled to the final drilling step. Thus, the wall 10 having high rigidity and cut-off performance is constructed to be widely applicable to large depth drilling and construction status where the groundwater leverl is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retaining wall and a method for constructing the retaining wall, and more particularly to a retaining wall and a method for constructing the retaining wall which have excellent water-stopping ability and can be constructed in a narrow construction site.

[0002]

2. Description of the Related Art FIG. 5 and FIG. 6 show soil retention assuming a case where a buried pipe 70 penetrates the excavation planes 53 and 63, and further ground excavation is performed such that the groundwater level is within the expected depth of excavation. It is a top view showing an example of plane arrangement of a wall. FIG. 5 is a plan view showing an example of a temporary earth retaining wall using the steel sheet pile 51 (sheet pile) as the earth retaining wall 50. The size of the steel sheet pile 51 to be used is previously determined by design depending on the working earth pressure of the excavated ground and the groundwater level position. FIG. 6 is a plan view showing an example of a temporary earth retaining wall using the soil cement column wall 61 as the earth retaining wall 60. The soil cement pillar row wall 61 excavates the wall body construction position in a columnar shape with an auger equipped with a stirring blade, and at the same time, stirs and mixes the cement-based hardening material with the in-situ soil of the excavated portion to form a columnar improved body in the ground. And a stress-bearing material for bearing the bending stress of the wall body is inserted into the columnar improved body to form a continuous wall. Normally, a multi-axis auger is used to form a plurality of columnar improved bodies at the same time to construct a continuous wall. In this example, H-section steel 6
2 is used as a stress bearing material.

Further, in all the conventional examples, the excavation range 53,
At the position where the buried pipe 70 passing through 63 intersects with the retaining walls 50, 60, the retaining walls 50, 60 cannot be constructed. Therefore, a chemical solution should be injected in advance up to the depth of the rooting for protection work. The columnar portion 71 formed by injecting the chemical liquid is designed to bear the working earth pressure in place of the earth retaining walls 50 and 60.

[0004]

However, since the steel sheet pile is an off-the-shelf product, the maximum proof stress is specified by the product, and when a large working earth pressure is generated such as deep-depth foundation excavation, the maximum size Even if steel sheet piles are used, the retaining wall's proof strength may be insufficient, and it may not be possible to meet the design requirements. Moreover, since the steel sheet piles that are adjacent to each other are connected by locking the hooks at the ends, sufficient water stoppage is possible when the groundwater level is high or when penetrating the confined layer. You can't get the effect. Therefore, it is necessary to install a predetermined drainage means on the excavation side.

On the other hand, the soil cement column wall can obtain high rigidity as a retaining wall by appropriately setting the size of the stress-bearing member, the installation interval, and the like. Moreover, since the walls are continuously constructed, the water stopping performance is also very good.
However, a large crawler type base machine equipped with a multi-axis auger is used, and ancillary equipment such as a soil plant is also required, which requires a large occupied area. For this reason, it cannot be used for construction in a limited construction area, such as under-road excavation already in use.

[0006] Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, and to provide a soil retaining wall which can be constructed by a compact construction machine and has a high water stopping performance, and a construction method thereof. .

[0007]

In order to achieve the above object, the present invention provides a stress-bearing pile material built at a predetermined interval along the outer periphery of a ground excavation area, and a part of the stress-bearing pile material. It is characterized by comprising a high-pressure injection stirring pile having a columnar continuous wall formed between the stress-bearing pile members adjacent to each other in a closely contacted state.

As a method of constructing the earth retaining wall, stress-bearing pile members are buried along the outer periphery of the ground excavation area at predetermined intervals, and the stress-bearing pile members adjacent to each other in a state of being in close contact with a part of the stress-bearing pile members. It is characterized in that high-pressure injection stirring piles are sequentially formed between the pile materials so as to surround the ground excavation range.

Further, it is preferable that the stress bearing pile material uses H-section steel as the pile material.

[0010]

According to the present invention, as a method of constructing an earth retaining wall, stress-bearing pile members are buried along the outer periphery of the ground excavation area at predetermined intervals, and the stress-bearing pile members are adjacent to each other in a state in which they are in close contact with each other. By constructing high-pressure injection stirring piles between each of the stress-bearing pile materials to sequentially surround the ground excavation range, a compact construction machine efficiently creates a retaining wall with high rigidity and water stopping performance. Can be built.

Further, by using the H-section steel as the stress-bearing pile material, the range on the excavation side becomes clear, so that the excavation accuracy is improved and the flange portion of the H-section steel is waterproof. As it functions as a plate, it also improves the waterproof performance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a retaining wall and a construction method thereof according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a top end portion of a retaining wall 10 according to the present invention.
H-shaped steel pile 1 along the outer periphery of the foundation part 1 indicated by the two-dot chain line
1 is built with a predetermined interval. The H-shaped steel pile 11 functions as a stress bearing pile material for the retaining wall 10 according to the present invention. For this reason, the pile length of the H-shaped steel pile 11 is set to a length such that the tip of the pile reaches the rooting length position required in design. Size of H-section steel used, building interval P
Is determined in consideration of the maximum earth pressure during excavation.
Furthermore, H-shaped steel piles 1 installed with a building interval P
A high-pressure injection stirring pile 20 is provided between the columns 1. The high-pressure injection stirring pile 20 is constructed by a known ground improvement method for forming a columnar solidified body in the ground. As a construction method, the hardened material is injected into the ground at a high pressure and high speed, and the surrounding ground is cut with the energy of the hardened material, and at the same time, the injected hardened material and the in-situ soil are mixed and stirred. A columnar solidified body is created in Yamauchi. As the hardening material, the cement-based hardening material was used in this embodiment, but a water glass-based hardening material or the like can also be used if the mixing device is changed.

In this construction method for constructing the high-pressure jet stirring pile 20, (1) a boring hole is drilled in the ground and a double pipe is inserted into the boring hole depending on the ground conditions and the diameter of the construction pile.
A method of spraying a hardened material in the ultra-high pressure state accompanied by air from the tip of the double pipe into the ground to cut the ground, and at the same time, to form a cylindrical solid body in the range where the hardened material is spread (representative example is JSG (2) and (2) while rotating the triple pipe inserted in the boring hole in which the casing is built, super high pressure water accompanied by air is jetted into the ground to cut the ground. At the same time as discharging that slime to the surface,
It is preferable to selectively use a method in which a hardening material is filled in the slightly formed cylindrical voids to form a cylindrical solid body (a typical example is a column jet grout method).

Unlike the soil cement column wall, this high-pressure injection stirring pile 20 is formed between the H-shaped steel piles 11 already built in. However, as shown in FIG. Since it is constructed in close contact with the H-shaped steel pile 11, H
The shaped steel pile 11 and the high-pressure injection stirring pile 20 are integrated. Therefore, the flange 11a of the H-shaped steel pile 11 can function as a water stop plate between the adjacent high-pressure injection stirring piles 20, and unlike the soil cement column wall, without considering the overlapping portion between the piles. Therefore, a sufficient water blocking effect can be obtained.

Further, in the soil cement column wall, since the size of the stress-bearing pile material is large with respect to the diameter of the columnar solidified body, the wall portion of the soil cement is stress-bearing pile material against the working earth pressure. It was necessary to treat it as a horizontal member with the H-shaped steel pile 11 as a fulcrum as a fulcrum, and examine diagonal tensile fracture, punch shear fracture, and the like. On the other hand, the columnar solidified body formed by the high-pressure injection stirring pile 20 is the H-shaped steel pile 1
Since it has a large diameter with respect to 1, it has sufficient proof stress against working earth pressure, and the working earth pressure is H-shaped steel pile 11
Can be transmitted smoothly. The pile length of the high-pressure injection stirring pile 20 is preferably set to be longer than the rooting length of the H-shaped steel pile 11. When the final excavator is expected to be affected by boiling or heaving, it is preferable to further extend the tip of the high-pressure injection stirring pile 20 to a depth that can prevent the occurrence of boiling or heaving.

Further, even when the buried pipe 70 is present at the planned excavation position, the H-shaped steel piles 11 are built with a space P therebetween as shown in FIG. In the case of the buried pipe 70, by adjusting the built-in position of the H-shaped steel pile 11, the high-pressure injection stirring pile 20 can be constructed without performing additional protective work for the buried pipe 70. Therefore, the buried pipe 70 is held so as to penetrate a part of the high-pressure jet stirring pile 20 as illustrated. When excavating the position of the buried pipe 70 in this state, it is preferable to apply a predetermined suspension protection work (not shown) to the buried pipe 70 that has been excavated and exposed in the excavation space.

FIGS. 2 (b) and 2 (c) are partial plan views of a wall body showing a modified example in which a steel sheet pile is used as the stress bearing pile material. In the same figure (b), the entire steel sheet pile 12 is a high-pressure injection stirring pile 20.
It is embedded inside, and the flange 12a is located at the position where the high-pressure jet stirring pile 20 contacts, and functions as a water stop plate. Further, in the same figure (c), construction is performed so that the flange 12a of the steel sheet pile is exposed on the excavation surface side, and the high pressure injection stirring pile 20 is provided with a predetermined overlap 20 at the back position of the steel sheet pile.
It is constructed while taking a. Also in this case, if the steel sheet pile web 12b is surely buried in the high-pressure jet stirring pile 20, the sufficient water-shielding effect is obtained without forming the overlap 12a between the high-pressure jet stirring piles 20 adjacent to each other. be able to. Although not shown, in addition to H-section steel and steel sheet pile, steel pipe sheet pile, precast concrete pile and the like can be used as the stress bearing pile material.

Next, a method of constructing a retaining wall according to the present invention will be described.
This will be described with reference to FIGS. First, as shown in FIG. 3 (a), the H-shaped steel piles 11 as stress bearing pile members are arranged at intervals P along the outer periphery of the foundation part 1 to be constructed whose outline is shown by a two-dot chain line in the figure. Open and build. This H-shaped steel pile 11
The intervals and sizes of are set so that the member stress is equal to or less than the allowable stress level with respect to the maximum earth pressure generated in the excavation stage. In addition, when the buried pipe 70 is in the planned excavation range, the buried pipe 70 should be positioned so that it is located between the H-shaped steel piles 11.
It is preferable to adjust the built-in position of the shaped steel pile 11.
A rotary boring machine (not shown), which is a small construction machine, is used to build the H-shaped steel pile 11. The boring rod connected to this rotary boring machine is rotated, and a drill bit is attached to the tip of the boring rod to make a hole. At this time, drilling is performed while circulating the muddy water discharged from the bit, and then
H-shaped steel as a stress bearing pile is built in the hole (BH method is known as a typical construction method). If necessary, the periphery of the H-section steel may be solidified with tremy concrete to form a pile of columnar solidified bodies.

After the H-shaped steel piles 11 have been built over the entire outer circumference, the high-pressure injection stirring piles 2 are provided between the adjacent H-shaped steel piles 11 tubes.
Create 0. Here, JS about the construction procedure of this pile
The G method will be briefly described as an example. First, a boring hole having a predetermined hole diameter is drilled by a double pipe at an intermediate position between the flanges of the adjacent H-shaped steel piles 11. After drilling for a specified pile length, while rotating the double pipe, the ultra-high pressure hardening material and compressed air are jetted toward the surrounding ground, and ground cutting and pile building are performed at the same time. At this time, if the ultra-high pressure hardening material is injected near the ground surface, the disturbance of the ground becomes large. Therefore, it is also preferable to separately improve the ground near the ground surface by a replacement method or the like.
In this way, as shown in FIG. 3B, the H-shaped steel pile 11
The columnar continuous wall can be formed by sequentially constructing the high-pressure injection stirring pile 20 in the direction indicated by the arrow between them. It is economical to set the diameter of the high-pressure jet stirring pile 20 to a length equal to the distance between the webs of the adjacent H-section steel piles 11 as shown in FIG. After the high-pressure injection stirring pile 20 has been formed over the entire circumference as shown in FIG. 3C, the range surrounded by the retaining wall 10 is divided into several excavation stages and excavated to the final excavator.

Each of the drawings in FIG. 4 is a sectional view showing the sections of the H-shaped steel pile 11 and the high-pressure injection stirring pile 20 along with the steps of construction. As shown in FIG. 4A, the pile length of the H-shaped steel pile 11 is the sum of the excavation depth and the designed root length, as in the conventional retaining wall. The high-pressure jet stirring pile 20 has a pile length (wall length) longer than that of the H-shaped steel pile 11, and when the excavated ground is composed of alternating layers of a permeable layer and an impermeable layer, it is constructed up to a range that penetrates to the impermeable layer. . (See FIG. 4B.) FIG. 4C is a cross-sectional view showing a state where the final excavator has been excavated. As shown in FIG. 3C, the H-shaped steel pile 11
Since the flange 11a is exposed to the side of the excavation space, there is also an advantage that the flange surface can be used as an excavation guide to perform accurate foundation excavation.

[0021]

As is apparent from the above description, according to the present invention, a soil retaining wall having a relatively high rigidity and water stoppage is provided.
Since it can be efficiently constructed with a small construction machine, it has an effect that it can be widely applied to various construction situations such as deep-drilling and high groundwater level.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a part of a retaining wall according to the present invention.

FIG. 2 is a partial plan view showing an example of a stress-bearing pile material used for the retaining wall of the present invention.

FIG. 3 is a construction sequence diagram showing an example of a procedure for constructing a retaining wall according to the present invention.

FIG. 4 is a cross-sectional view showing a cross-sectional shape at each construction stage of the retaining wall shown in FIG.

FIG. 5 is a plan layout view showing an example of a retaining wall made of a conventional steel sheet pile.

FIG. 6 is a plan layout view showing an example of a retaining wall made of conventional soil cement column walls.

[Explanation of symbols]

 10 Earth retaining wall 11 H-shaped steel pile 12 Steel sheet pile 20 High-pressure injection stirring pile 70 Buried pipe

Claims (3)

[Claims] 1. A stress-bearing pile material built at a predetermined interval along the outer periphery of a ground excavation area, and between each of the stress-bearing pile materials adjacent to each other in close contact with a part of the stress-bearing pile material. A soil retaining wall, which is constructed and is composed of high-pressure jet stirring piles that form a columnar continuous wall. 2. A stress-bearing pile material is embedded at a predetermined interval along the outer periphery of a ground excavation area, and a high pressure is sequentially applied between the stress-bearing pile materials that are adjacent to each other in a state of being in close contact with a part of the stress-bearing pile material. A method of constructing an earth retaining wall, characterized in that an injection stirring pile is formed and an earth retaining wall is constructed so as to surround the ground excavation range. 3. The earth retaining wall according to claim 1, wherein the stress-bearing pile material uses H-shaped steel as the pile material.