JPH07197450A - Earth retaining wall in soft ground and soil improvement method by use thereof - Google Patents

Abstract

PURPOSE:To prevent a precipice from falling dot and improve the safety, by using a composite improving body which is inserted in an ordinary improving body like a rigid I-shaped steel as a self-standing earth retaining wall. CONSTITUTION:A vertical excavated hole is made in the ground 2 by an excavator and at the same time, an ordinary ground mixed and agitated with slurry is made in the excavated part 2a. Before the excavated part 2a is solidified, rigid materials like I-shaped steel, H-shaped steel, or sheet piles are inserted therein with pressure to unify them together and form a composite improving body 5 of which external faces are mutually superposed as a self-standing earth retaining wall. Thereafter, excavating works are carried out as far as the excavating face 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-supporting mountain retaining wall applied to soft ground and a self-supporting mountain retaining method using the self-supporting mountain retaining wall.

[0002]

2. Description of the Related Art Conventionally, after excavating a ground into a column by an excavator, a slurry composed of a mixture of water and an insoluble matter such as lime or gypsum is poured and stirred. However, the soil cement column, which is a soil improvement body solidified in the ground, constitutes the mountain retaining wall of soft ground. This mountain retaining wall and the mountain retaining method are disclosed in JP-A-4-
This is disclosed in Japanese Patent Publication No. 115016 (prior example).

The soil cement column in the preceding example has been increasingly used as a mountain retaining wall with high waterproofness, but has a problem in strength, requiring a considerable site area around the building. . Therefore, if there is no room in the area around the building, some measures were required to increase the strength and prevent the building from collapsing. In addition, in the self-supporting mountain retaining method using the ground improvement body, the stability of the ground has been secured by cutting the ground, but when the cut surface is an upright wall, the improvement body is a brittle material and the excavation depth is deep. When the size became large to some extent, there was a danger of collapse due to earth pressure.

[0004]

In view of the above circumstances, the present invention is configured as follows. In claim 1, at the same time as excavating the ground into a columnar shape by an excavator, at the same time, in the mountain retaining wall in the soft ground formed by arranging a plurality of ground improving bodies mixed with stirring and mixing with each other, the adjacent ground improving bodies have outer peripheral surfaces thereof. Are integrated with each other and are formed integrally by inserting steel materials such as I-shaped steel or H-shaped steel and sheet pile having high rigidity inside. According to the second aspect of the present invention, at the same time as excavating the ground into a columnar shape by the excavator, the outer peripheral surfaces of the adjacent ground improving bodies are overlaid on each other in the mountain retaining wall in the soft ground formed by arranging a plurality of ground improving bodies mixed with the slurry by stirring. As a wrap, a general improved body mixed and formed with the earth and sand and a slurry, and a self-standing mountain retaining wall with the composite improved body,
The composite improved body is reinforced by the general improved body. In claim 3, the general improvement body according to claim 2 is provided on the earth pressure generation side where earth pressure is generated or the earth pressure passive side where earth pressure is received with respect to the composite improvement body, and the composite improvement is provided. It is configured to reinforce the body. In claim 4, when the ground is excavated in a pillar shape by an excavator, and the earth and sand in the pillar are mixed and mixed with the slurry in the pillar, and the ground improvement bodies stirred in the ground are arranged next to each other. After forming a viscous ground improvement body so that it will polymerize with the steel, I-shaped steel or H-shaped steel with high rigidity, steel material I-shaped steel such as sheet pile is inserted into the viscous ground improvement body, and then the viscous ground improvement body is solidified. Then, the Yamadome method was constructed so as to form a self-supporting Yamadome wall by the composite improved body. According to a fifth aspect of the present invention, in the mountain retaining method according to the fourth aspect, the extension direction of each viscous ground improvement body is such that the top surfaces of the I-shaped steels inserted into the viscous ground improvement body face in the earth pressure direction. The I-shaped steels are arranged in parallel along.

[0005]

According to this structure, the present invention has the following functions. In claim 1, the self-supporting mountain retaining wall is mixed with earth and sand and slurry in the ground to form a ground improvement body,
Since a plurality of ground improvement bodies are arranged side by side so that the outer peripheral surfaces of adjacent ground improvement bodies overlap each other,
Motoyama retaining wall has a high waterproofing property, and since the I-shaped steel with high rigidity is inserted inside the ground improvement body to form a composite improvement body, it has high bending resistance, prevents collapse and secures safety. However, it is also effective when there is no room for the site area around the building. In claim 2, since the composite improved body of claim 1 is configured to be reinforced by the general improved body formed by mixing the earth and sand and the slurry so that the adjacent ground improving bodies overlap each other, The waterproofness and safety can be further enhanced. In claim 3, the general improvement body for reinforcing the composite improvement body is provided alternatively on the earth pressure generation side where earth pressure is generated or on the earth pressure passive side where earth pressure is received, and is constituted alternatively. is there. If there is a lot of site area around the building, a general improvement body for reinforcement can be installed on the earth pressure generating side.If there is no space on the site area, general reinforcement for reinforcement is available on the earth pressure passive side. A body is provided, and both can improve water stopping performance and safety.
In Claim 4, after forming the viscous ground improvement body which mixed the sand and the slurry so that the ground improvement body stirred in the ground may be overlapped with each other when they are arranged next to each other, the viscous ground improvement body is formed. It is configured to insert a highly rigid I-shaped steel, etc., and then solidify the viscous ground improvement body to form a self-standing mountain retaining wall that is a composite improvement body.
It is possible to provide a self-standing mountain retaining wall with high water resistance, high bending resistance, prevention of collapse, and high safety. In claim 5,
In the self-supporting mountain retaining method according to claim 4, since the top surfaces of the I-shaped steels inserted into the viscous ground improvement body are set to face each other in the earth pressure direction, the bending strength of the composite improvement body is further enhanced. Is.

[0006]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are merely illustrative examples, without any intention of limiting the scope of the present invention thereto unless otherwise specified. Absent.

FIG. 1 is a first view showing a self-supporting Yamadome wall according to the present invention.
Fig. 2 is a second embodiment showing the self-supporting mountain retaining wall according to the present invention, Fig. 3 is a third embodiment showing the self-supporting mountain retaining wall according to the present invention, and Fig. 4 is a ground improvement body. FIG. 5 is a diagram showing a conventional example of the self-supporting Yamatome construction method, FIG. 5 is a plan view of Yamadome, and FIG. 6 is an example of construction using a biaxial excavator.

In FIG. 1A, the excavated portion 2 of the ground 2
The composite improved body 5 in which the I-shaped steel 4 is inserted in a is shown.
The arrow P indicates the earth pressure direction. FIG. 1 (b) is a plan view of FIG. 1 (a), and a part of the outer peripheral surfaces of adjacent ground improvement bodies are overlapped and connected to each other, and the combined improvement bodies 5 are shown in a line. In FIG. 2A, the excavation portion 2a of the ground 2 is I
An example is shown in which the composite improvement body 5 having the shaped steel 4 inserted therein and the general improvement bodies 6 and 7 for reinforcing the same are provided on the side receiving earth pressure. The arrow P indicates the earth pressure direction. FIG. 2B is a plan view of FIG. 2A, in which a part of the outer peripheral surfaces of adjacent ground improvement bodies are overlapped and connected to each other, and the composite improvement bodies 5 arranged in a line and a general improvement body that reinforces the same. 6 and 7 are shown. In FIG. 3 (a), an example is shown in which a composite improvement body 5 in which an I-shaped steel material is inserted in the excavated portion 2 a of the ground 2 and a general improvement body 8 for reinforcing the same are provided on the side where earth pressure is generated. ing. FIG. 3B is a plan view of FIG. 3A, in which a part of the outer peripheral surfaces of adjacent ground improvement bodies are overlapped and connected to each other, and a combined improvement body 5 arranged in a line and a general improvement body that reinforces it An example is shown in which two 8 are provided at a predetermined interval. FIG. 4 shows an example in which the site area from the road 2b has a margin and the general improvement bodies 9 are arranged in three rows.

FIG. 5 is a plan view of Yamadome of the foundation work to which the Yamadome wall according to the present invention is applied. The ground is a continuous soft alluvium composed of silt layers up to about 35 m, especially Motoyamadome. The standard penetration test value N up to 12 m to which the wall is applied is partly showing 20 or more, but it shows a low N value of almost 10 or less, and the ground with an N value of 50 or more which can be regarded as a supporting ground. Is a diluvial deposit around 43 m from the ground surface GL, and the groundwater level is GL-1.3 m. The excavation scale of the foundation work is 79.8m x 49.2m, and the depth is GL in the general section.
It is -5.2 m (the deepest part GL-6.5 m). Line A,
B and C are road boundaries, and lines D and E are site boundaries. The shaded portions 10 and 11 are areas in which the ground is improved by the general improved body and the composite improved body, and particularly, the shaded portion 11 is a water blocking wall. Cases 1 to 5 are classified according to site conditions.

Next, various devices used in the present invention will be described. In FIG. 6, the excavator 1 is fixed on the ground 2 by a device (not shown) during excavation, and is provided so as to be movable on the ground 2 when the excavation position is changed after excavation. The excavator 1 has a stirring section 1e having stirring blades.
And a stirring rod 1a having a digging portion 1c at its tip and a stirring rod 1b having a stirring portion 1f and a digging portion 1d. The excavated portions 1c and 1d each have a diameter of φ1m, and when excavated in the ground 2, the excavated portions are slightly vertically moved so that circles of φ1m overlap each other to form the shape shown in FIG. 6 (b). They are staggered. Stirrer 1
Although only a pair of e and 1f are drawn for convenience, a plurality of e and 1f are provided on the respective stirring rods so as to be offset from each other. Inside the stirring rods 1a and 1b, a passage through which slurry mixed and mixed in a plant device (not shown) passes is provided, and the slurry is discharged from an excavation part at the tip or an outlet near the excavation part, not shown. Is configured. The excavation part, the stirring part and the stirring rod are the supporting parts 1g.
Are held at a predetermined position with a predetermined interval.

Next, the mountain retaining method for ground improvement according to the present invention will be described. First, the soil at the construction site is collected by a sampler and a soil inspection is conducted.The amount of cement-based or lime-based solidifying material mixed is measured based on the data, and water is added to the solidifying agent according to the determined solidifying agent mixture. Mix well with a mixer to prepare a slurry.

Next, the axes of the stirring rods 1a and 1b of the excavator 1 in FIG. 6 are set on the excavated portion 2a of the ground 2, and the excavator 1 is started to rotate the stirring rods 1a and 1b forward. When the excavation parts 1c and 1d at the tip of the stirring rod start excavation at a constant speed, the slurry is discharged to the vicinity of the excavation part and stirred and mixed with the sand by the stirring parts 1e and 1f.

When the excavation parts 1c, 1d reach a predetermined depth, the discharge of the slurry is stopped, the stirring rods 1a, 1b are reversed, and the stirring parts 1e, 1f rise at a constant speed while stirring and mixing. When the excavation parts 1c and 1d leave the ground surface of the ground 2, the excavator 1 moves laterally by 0.8 m and starts new excavation.

When the excavation and mixing are performed a predetermined number of times in this manner, a guide ruler (not shown) is set in alignment with the axis of the excavated portion 2a. After that, the I-shaped steel 4 is inserted into the guide hole 3b and pressed by a vibro hammer (not shown) to insert the I-shaped steel 4 into the excavated portion 2a. After insertion,
The mixture of slurry and earth solidifies, a composite improved body is formed, and a self-standing mountain retaining wall is completed.

After that, excavation work is performed up to the root cutting surface 12 to complete the self-supporting mountain retaining wall shown in FIG. However, when it is expected that the magnitude of the earth pressure P exceeds the bending strength and stability of the composite improving body 5, the stirring rod is set further on the root cutting surface 12 closer to the composite improving body 5. Then, as shown in FIG. 2, a general improved body 6 in which the I-shaped steel 4 is not inserted is formed. The stress due to the earth pressure P is the root cutting surface 1 of the composite improvement body 5.
Since it concentrates in the vicinity of 2, it is still more effective to provide the general improving body 7 shorter than the general improving body 6.

In FIG. 1, when there is a margin of site area on the side where the earth pressure P is generated, as shown in FIG. 3, it is necessary to provide the general improvement body 8 on the earth pressure generation side at an appropriate interval. Can be reduced, which is more effective than FIG.

Based on the above-mentioned circumstances, an experiment on the Yamadome wall was conducted prior to the excavation work. In Fig. 5, according to the site conditions, it is classified into five cases 1-5, and while changing the mixing amount of the solidifying material for each case, the improvement rate and the improvement range are determined based on the soil investigation result, and the construction is carried out. I did. In Cases 1 to 3 where there is room on the periphery of the building, there is no room on the self-supporting mountain retaining wall of the conventional general improvement body (up to 11 m, diameter φ1 m, pitch 0.8 m) shown in FIG. In Cases 4 and 5, self-standing mountain retaining walls were constructed by the composite improved body (length 6.5 to 12 m, diameter φ1 m, pitch 0.8 m) into which the I-shaped steel shown in FIG. 1 or 2 was inserted.

From the measurement results, it was confirmed that the function as a self-supporting mountain retaining wall was sufficient, there was almost no effect on the surrounding ground, the construction period could be greatly shortened, and economical construction could be provided. Was confirmed. In particular, it is an improved construction method that exerts its power as a self-supporting mountain retaining wall with water stoppage in excavating GL-5.0 to 6.0 m of soft ground.

[0019]

[Effect] As described above, the self-supporting mountain retaining wall and the ground improvement method using the mountain retaining wall according to the present invention have the following effects. Since the composite improved body, which is made by inserting highly rigid I-shaped steel into the general improved body, is configured as a self-standing mountain retaining wall, it has a high bending resistance, prevents collapse, secures safety, and protects the site around the building. It is also effective when you cannot afford it. In addition, when the composite improved body is reinforced with the general improved body formed by mixing earth and sand with the slurry, the waterproofness and safety can be further enhanced. In addition, when the general improver that reinforces the composite improver is provided by increasing the number of layers in the portion close to the ground surface, the waterproofness and safety can be further enhanced. Further, when the I-shaped steel is inserted with the top surface of the I-shaped section facing in the earth pressure direction, the bending strength of the composite improved body can be further increased.

[Brief description of drawings]

FIG. 1 is a first embodiment of a self-standing mountain retaining wall according to the present invention.

FIG. 2 is a second embodiment of the self-standing mountain retaining wall according to the present invention.

FIG. 3 is a third embodiment diagram showing a self-supporting mountain retaining wall according to the present invention.

FIG. 4 is a diagram showing a conventional example of a mountain retaining wall.

FIG. 5 is a plan view of Yamadome.

FIG. 6 is a diagram showing a construction example using a biaxial excavator.

[Explanation of symbols]

 1 Excavator 2 Ground 4 I-shaped steel 5 Composite improved body 6, 7, 8, 9 General improved body 10 Ground improved range 11 Water stop wall 12 Root cut surface

Claims (5)

[Claims] 1. In a mountain retaining wall in soft ground formed by arranging a plurality of ground improvement bodies that are agitated and mixed with a slurry at the same time as excavating the ground into a columnar shape by an excavator, the adjacent ground improvement bodies have an outer peripheral surface. A self-supporting mountain retaining wall in soft ground, characterized by being a composite improved body that is formed integrally by inserting steel materials such as I-shaped steel or H-shaped steel, sheet pile, etc., which are superposed on each other and have high rigidity. 2. In a mountain retaining wall in a soft ground formed by arranging a plurality of ground improvement bodies that are agitated and mixed with a slurry at the same time as being excavated in a columnar shape by an excavator, outer peripheral surfaces of adjacent ground improvement bodies are polymerized with each other. ,
A general improved body formed by mixing the earth and sand and a slurry, and a composite improved body integrally formed by inserting a steel material such as I-shaped steel or H-shaped steel having a high rigidity or a sheet pile into the inside of the general improved body. The self-standing mountain retaining wall in soft ground, characterized in that the general improved body is configured to reinforce the composite improved body. 3. The self-supporting mountain retaining wall according to claim 2, wherein the general improvement body is provided on the earth pressure generating side or the earth pressure passive side of the composite improvement body. 4. An excavator is used to excavate the ground in a columnar shape, the generated soil is stirred, and mixed with a slurry in the ground to form a viscous ground improvement body so that adjacent portions are polymerized, A steel material such as a highly rigid I-shaped steel or H-shaped steel or sheet pile is inserted into the viscous ground improvement body, and then the viscous ground improvement body is fixed to form a mountain retaining wall by the composite improvement body. Yamadome method on soft ground. 5. The mountain in soft ground according to claim 4, wherein the I-section steels are arranged in parallel along the extending direction of the respective viscous ground improvement bodies so that the top surfaces of the I-section steels face each other in the earth pressure direction. Staying method.