JP4080777B2 - Ground improvement method and apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improved construction method for soft ground where liquefaction is likely to occur, and an apparatus used for the construction method.
[0002]
[Prior Art and Problems to be Solved by the Invention]
Various methods have been proposed and implemented for the soft ground improvement method. For example, a means for forming a hardened pile in the ground (Japanese Patent No. 2804896, etc.), a sand pile is adopted instead of the hardened pile, and a sand drain method in which the sand pile plays a role of a drainage column, or sand is pressed in. A sand compaction pile construction method for closing, hardening and hardening is known.
[0003]
The present invention aims to prevent liquefaction, and in improving the ground along this purpose, it is not sufficient to simply construct a hardened pile or a drainage column. As a method corresponding to the purpose, a sand compaction pile method is adopted.
[0004]
That is, for sandy ground, sand pile construction work itself becomes compaction due to vibration and the ground clearance ratio is reduced, and for clay ground, it is handled as a composite ground of sand pile and cohesive soil. , Preventing liquefaction due to ground homogeneity.
[0005]
However, the sand compaction pile method is used for sand piles, because sand is pressed into the excavation hole and closed by vibration, which affects nearby structures due to vibration, especially in residential areas. It is a construction method that cannot be done.
[0006]
In the case of the vibration press-fitting, there is a limit to the pile depth. Furthermore, the normal improvement target ground is clayey in the surface layer part and sandy ground in the lower layer part, but the liquefaction prevention method for such ground has not been established.
[0007]
Therefore, the present invention proposes a new construction method for constructing a sand pile by excavation consolidation.
[0008]
[Means for solving the problems]
In the ground improvement method according to the present invention, a casing provided with a shell-like cutting edge whose end can be opened and closed is pressed into the surface layer portion after the end is closed, and then the end is opened, and the excavated body in the casing is opened from the end of the casing. The excavation soil is pushed to the appropriate depth while pressing the excavation soil against the peripheral wall of the excavation hole, and after excavation, the excavation hole is filled with an appropriate filler.
[0009]
Therefore, a sand pile (including other than sand) can be constructed without vibration, and the peripheral wall of the sand pile is in a compacted state, and therefore has the same strength as a pile constructed by applying pressure by vibration.
[0010]
Embodiment
Next, an embodiment of the excavator of the present invention used for carrying out the method of the present invention will be described. The excavation apparatus shown in the embodiment includes a casing 1 and an excavation body 2.
[0011]
The casing 1 has a size corresponding to the excavation diameter, is attached to a predetermined heavy machine A, and is moved up and down. In particular, the distal end portion 11 is a shell-shaped cutting edge that can be opened and closed.
[0012]
The excavation body 2 is a conventional compacted excavation rod, which has a excavation bit at the tip and a screw blade and an outer peripheral pressing plate at the tip, and is driven to rotate by a drive mechanism 3 disposed above the casing 1. Become.
[0013]
Thus, in the ground improvement using the above-mentioned device, for the surface layer portion a which is a silt layer (clay layer), the front end portion 11 of the casing 1 is closed, and the weight of heavy machinery A is used as necessary. Pressure is applied to cause the casing 1 to sink.
[0014]
Next, the sandy layer b under the silt layer a is excavated. When the sandy layer b that receives the resistance of the settlement of the casing 1 is reached, the tip 11 of the casing 1 is opened and the excavated body 2 is rotated. Drive and excavate.
[0015]
In this excavation, the excavated soil is pushed upward against the excavation hole and pressed against the peripheral wall of the hole to excavate the peripheral wall in a consolidated state.
[0016]
When the excavation to the depth required for the construction of the sand pile c is completed, the casing 1 and the excavated body 2 are pulled out. After that, the sand pile c is constructed by filling and compacting predetermined sand into the excavation hole.
[0017]
Accordingly, it is possible to construct a sandpile c having a desired depth without vibration, and the peripheral wall of the sandpile c is brought into a compacted state by press-fitting the casing 1 and pressing the excavated body 2 against the peripheral wall of the excavated soil. Therefore, a pressure density similar to that of vibration press-fitting is provided.
[0018]
Note Te present invention method odor, sand piles, without employing the sand, plastic waste, etc., if it has a suction drainage function (lowering the water table by suction of ground water by capillary action), any member May be used.
[0019]
【The invention's effect】
As described above, according to the present invention, after the excavation casing is press-fitted into the surface layer portion or without being press-fitted, the excavation soil is directly pressed against the peripheral wall of the excavation hole and drilled to an appropriate depth, and after excavation, the excavation hole is filled with an appropriate filler. In this ground improvement method, the sand pile (including other than sand) that can be used to prevent liquefaction can be easily constructed without vibration and to a desired depth.
[Brief description of the drawings]
FIG. 1 is a process explanatory diagram (casing press-fitting) of an embodiment of the method of the present invention.
FIG. 2 (at the start of excavation).
FIG. 3 (During excavation).
FIG. 4 (pile construction).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casing 11 Tip part 2 Excavation body 3 Drive mechanism

Claims (3)

After closing the tip and press-fitting the casing with a shell-like cutting edge whose tip can be opened and closed into the surface layer , the tip is opened, and the excavated body in the casing protrudes from the tip of the casing, and the excavated soil is surrounded by the peripheral wall of the borehole A ground improvement method that is formed by excavating to a suitable depth while being pressed against the surface, and filling the excavation hole with a filler having a suction drainage function after excavation. Ground improvement method according to claim 1, wherein the filler is sand. A casing with a shell-shaped cutting edge that can be opened and closed at the tip, a drill bit at the tip, a screw blade that lifts the excavated soil upward on the rod, and the peripheral wall is pressed by pressing the excavated soil against the hole inner wall A ground excavation apparatus for ground improvement characterized in that an excavation body including an outer peripheral pressing plate is provided and can be excavated by advancing from the tip of the casing.

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