JP2002115245A - Columnar molding and construction method for soil improvement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method for soil improvement, enabling an expansive admixture to be reliably infilled into the excavated hole downsized with the miniaturization of execution machinery and permitting the expansive admixture to be reliably infilled into even the obliquely or horizontally excavated hole during the soil improvement directly under an existing structure. SOLUTION: A cylindrical member having a prescribed length is formed of a material with impregnating ability and permeability. Columnar moldings for the soil improvement is manufactured so as to be constituted by infilling a material, such as quick lime, with water-containing expansivity into the cylindrical member. The columnar moldings are charged and infilled into many excavated holes formed in the soft ground saturated with ground water for the purpose of forming a columnar group. After that, the expansion of materials due to impregnation with the ground water brings about the compaction of the ground on the strength of a rise in confining pressure against the ground inside the columnar group, liquefaction based on the effect of an increase in density, and measures for bearing capacity. The columnar moldings precedently provided with different kinds of expansion performance are selectively disposed in the plural excavated holes varying in angle, size, etc., in order to uniformize the improvement effects within the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a columnar molded body for ground improvement and a ground improvement method.

[0002]

2. Description of the Related Art As a conventional technique, a casing auger is drilled by drilling and drilled vertically to a predetermined depth. From the top to the top, a plurality of structures filled with an expanding material are built to form a columnar group.

However, in the prior art, the construction machine such as a casing auger is very large, and the workability and adaptability on the site are small. Particularly, the ground improvement work of the existing structure in a narrow site environment is required. It is difficult to adopt this method for In addition, since the expansive material is charged in powder form as a mixture of quicklime and sand, it is usually necessary to fill it while applying internal pressure, and the mechanism is complicated. It is impossible in principle to ensure filling.

[0004] For the same reason, it is difficult to fill holes other than vertical holes such as diagonal or horizontal. Therefore, when the conventional method is applied to an existing structure, it can only be applied to the periphery of the structure. However, it was not possible to improve the ground of the ground directly under the structure, and it had to be an indirect countermeasure against phenomena such as settlement and liquefaction. In addition, when it is required to fill an arbitrary point of one drilling with an inflating material of various mixing ratios for reasons of design, implementation, economy, etc. It is difficult to maintain the quality accurately because it is performed in the body input work, and there is a problem that the work efficiency is greatly reduced.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is necessary to reduce the size of construction machines in order to improve the ground in a small site environment, including the case where an existing structure is targeted. is there. Also, in order to reduce the size of drilling holes due to the downsizing of the enforcement machine, it is necessary to provide a means for reliably filling the expanding material, and in order to make it possible to improve the ground directly under the existing structure, A means for reliably filling the drilling material with the expanding material is required.

In the case where the ground characteristics to be improved have uneven ground characteristics, it is necessary to provide a means for freely changing the remodeling rate in one drilling so as to achieve an even improvement. In addition, even if the drilling interval is not constant, it is necessary to provide a means for finishing to an even degree of improvement, improve the control of the compounding quality of the expanding material, and provide a means for surely installing the required expanding material at a predetermined point. is there.

[0007]

The means of the present invention are as follows. (1) A ground-improving columnar molded body in which a cylindrical member having a predetermined length is formed of a material having impregnation and water permeability, and a material having a water-swelling property such as quicklime is filled in the cylindrical member. (2) A ground improvement columnar compact formed by compressing a hydrous swellable substance such as quicklime to form a column of a predetermined length. (3) A columnar molded body with different expansion performance was created in advance according to design requirements. (4) A large number of holes are drilled in the soft ground saturated with groundwater, and the columnar formed body is formed by charging and filling the cylindrical shaped body into the holes, and then the columnar group is formed by material expansion due to impregnation of groundwater. The ground was compacted by increasing the restraining pressure of the inner ground. (5) A plurality of holes are formed on the ground surface around the structure by changing the angle, such as substantially oblique or horizontal, in a sectional view toward the lower side of the structure, and the cylindrical molded body is formed in the hole. A ground improvement method in which pillars are formed by charging and filling. (6) Improve the effect of improvement in the ground Equalize the effect of improvement in the ground by selecting and arranging cylindrical shaped bodies with different expansion performances in advance for a plurality of holes with different angles and sizes That you did.

[0008]

Embodiments of the present invention will be described below in detail. In the figure, reference numeral 1 denotes a cylindrical member, which is formed of a substance having impregnation and water permeability to a predetermined length (in the embodiment, the outer diameter is 200 mm and the length is 1.000 mm). A substance having a water-swelling property such as calcined lime (hereinafter referred to as an expanding material), 3 is a front end cap of the cylindrical member 1, and 4 is a rear end cap.

The cylindrical member 1 serves as an outer shell for reliably protecting and guiding the expansive material 2 accommodated up to the target position in the ground drilling at the time of construction, and takes time after reaching the target position. As time elapses, moisture is transmitted to the expanding member 2 to start expanding. At this time, the cylindrical member 1 is formed to have such strength that it is easily broken and does not hinder the expanding effect. When the tip cap 3 is inserted into the hole, the end is smooth so as not to be caught by the engaging portion of the sheath tube.

Further, since the cylindrical member 1 remains in the ground, it is harmless to the natural environment, and is made of, for example, paper, pulp, or the like, which is reduced to the soil over time, as a main raw material. Further, the expanding material 2 is a mixture of quicklime and aggregate for a desired degree of soil improvement, for example, in a material used for improvement in small-diameter drilling by a small machine, the ratio of quicklime is aggregate volume ratio. Is about 1: 1 or more. This is determined by the degree of improvement required because the drilling interval required for construction is about 1.0 m or more. In the embodiment shown in FIG. 3, the expanding member 2 is formed into a cylindrical body 2a having a predetermined length by compression using a mold or the like.

In the figure, reference numeral 5 denotes a sheath tube, and 6 denotes an engaging portion of the sheath tube 5. Numeral 7 denotes a tip bit of the sheath tube 5 for preventing earth and sand from flowing into the sheath tube 5. After the sheath tube 5 reaches a required depth and the filling of the cylindrical molded body is completed, the sheath tube 5 is closed. Is pulled out, the tip bit 7 remains underground. Reference numeral 8 denotes a propulsion rod which functions to fix the cylindrical molded body so that it does not rise when the sheath tube 5 is pulled out. When the sheath tube 5 is not used, it is possible to insert the columnar molded body into the drilled hole directly dug using a bentonite solution to prevent the collapse of the inner wall of the bore hole, and the same effect as when the sheath tube 5 is used. There is.

[0012]

Next, embodiments of the ground improvement method according to the present invention will be described in detail. FIGS. 7 and 8 show an example in which the ground immediately below the existing structure is improved, and show a state in which the liquefaction countermeasure construction has been performed on the installation portion of the oil tank 10. In this case, the area directly below is covered, and the depth is 1 m to 9 m from the ground surface. The oil tank 10 has a diameter of 14 m.

A plurality of boreholes 11 are formed around the oil tank 10, mainly from both sides, within a range including the necessary range for improvement, toward the basement of the oil tank 10, and a cylindrical molded body is formed in the borehole 11. Insert filling. The hole 11 varies depending on the dimensions of the cylindrical molded body to be inserted.
The diameter of the drill hole 11 is 250 m to insert the cylindrical molded body
m.

In the example shown in the drawing, the filling interval required for ground improvement is set to 1.0 m or less. In the cross-sectional view of FIG. The drilling hole 11 is formed at an angle to maintain it. FIG. 8 shows drilled holes 11 formed in parallel at intervals of 1.0 m in plan view.

Further, since the cylindrical shaped body can be applied to a normal vertical regardless of the angle at which the drilled hole 11 is filled, the ground improvement work can be performed irrespective of the new or existing construction site conditions. It can be performed.

Next, a specific method of forming the drilled holes 11 and filling the columnar molded body will be described in detail with reference to FIGS. First, as shown in FIG. 4, the sheath tube 5 is driven into a ground to a desired depth to form a drill hole 11 by a drilling machine.
Subsequently, as shown in FIG. 5, the cylindrical molded body is inserted into the sheath tube 5 by the propulsion rod 8, and the cylindrical molded body is filled from the end. The insertion of the columnar molded body into the desired area is completed, and the unimproved area near the surface is filled with earth and sand to complete the operation. Finally, as shown in FIG. 6, in a state where the inserted cylindrical molded body is fixed by the propulsion rod 8 so as not to rise together, the filling of the sheath tube 5 into the ground by retreating the sheath tube 5 is completed.

FIG. 7 shows that when a plurality of boreholes 11 are formed substantially obliquely in cross section from the ground surface, a phenomenon in which the gap between the boreholes 11 changes and the in-ground restraint pressure becomes uneven is considered in advance. Prepare a columnar molded body with a different degree of expansion, arrange the one with a high degree of expansion at the tip, and show the method of correcting by arranging the one with a low degree of expansion as approaching the ground surface, at the time of construction Plan based on detailed drawings designed based on ground survey materials.

Although the above embodiment has described the liquefaction countermeasure method for the oil tank, the present invention is not limited to the oil tank but various general structures such as high-rise buildings and apartment houses, as well as bridges, quays, roads and the like. It can also be applied to railway tracks and the like.

[0019]

According to the present invention, by using a columnar compact for ground improvement, the work efficiency is improved as compared with the generally used charging in the powder state, and the ground drilling saturated with groundwater. Can be reliably filled, and can be applied to small-diameter drilling by a small machine, and can be adapted to various site environments.

In addition, in order to improve the ground of an existing structure, an inflating material is filled from a ground surface around the structure to a lower portion of the structure at an angle that is different from the ground surface in a sectional view. In addition, the use of a columnar molded body ensures that the expansive material can be securely inserted into the entire drilled hole without using special mechanisms and without creating discrete parts or voids. However, it has made it possible to directly improve the structure of a large base plate.

Further, the columnar shaped body for ground improvement according to the present invention can be formed to have various inflation performances at a fixed size, so that, for example, the interval between the ground improvement holes is narrow near the ground surface and widened at the terminal end. In the case of a suitable arrangement, in the drilling group by selecting a columnar molded body with a large expansion coefficient at the end part in one drilling, and selecting a cylindrical molded body with a small expansion coefficient as approaching the ground surface The uniformity of ground confinement pressure can be secured. In addition, even when a different degree of improvement is required at an arbitrary position in plan view and cross-sectional view of the ground improvement drilling, a predetermined degree of ground improvement can be achieved at an arbitrary position within the improvement range only by selecting the cylindrical shaped body. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a front view of a columnar molded body for ground improvement according to the present invention.

FIG. 2 is an enlarged sectional view taken along line AA of FIG. 1;

FIG. 3 is a front view of a cylindrical molded body showing another embodiment.

FIG. 4 is an explanatory view showing a state in which a cylindrical molded body is inserted into a drilled hole.

FIG. 5 is an explanatory view showing a state in which the cylindrical molded body has been completely inserted into the sheath tube.

FIG. 6 is an explanatory view showing a state in which the cylindrical tube inserted into the sheath tube is pulled out with the propulsion rod holding down the cylindrical tube, and only the columnar member is installed in the ground.

FIG. 7 is a schematic cross-sectional view showing a state in which the ground improvement method according to the present invention has been performed on an oil tank.

FIG. 8 is a schematic plan view of FIG. 7;

FIG. 9 shows a state in which columnar molded bodies having different expansion performances are selectively disposed in order to make the degree of improvement within the improvement range uniform even when the angle and the interval change in the soil improvement method according to the present invention. Illustration

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical member 2 Expansive material 2a cylindrical body 3 Tip cap 4 Rear end cap 5 Sheath tube 6 Sheath tube engaging portion 7 Sheath tube tip bit 8 Propulsion rod 10 Oil tank 11 Drilling

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Shimohira 4-6-29 Namamugi, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Shining Plantech Co., Ltd. (72) Inventor Shohei Kato 3--20-16 Nishiazabu, Minato-ku, Tokyo No. Japan Sea Ocean Drilling Co., Ltd. (72) Inventor Nobuo Yamazaki 2-3-8 Shiba, Minato-ku, Tokyo Rinkai Construction Co., Ltd. (72) Inventor Masayuki Ohnami 4-53-3, Chuo, Nakano-ku, Tokyo 2D043 CA04 CA12 DA06 EA04

Claims (6)

[Claims] 1. A ground improvement circle characterized in that a cylindrical member having a predetermined length is formed of a material having impregnating properties and water permeability, and a material having a water-swelling property such as quicklime is filled in the cylindrical member. Columnar molded body. 2. A column-shaped body for ground improvement, wherein a substance having a water-swelling property, such as quick lime, is compressed and formed into a column having a predetermined length. 3. A columnar shaped body for ground improvement according to claim 1, wherein said shaped body is made in advance so as to have different expansion performances according to design requirements. 4. A plurality of holes are drilled on a soft ground saturated with groundwater, and the columnar shaped body is charged and filled into the holes to form a columnar group. , Soil compaction by increasing the confining pressure of the ground in the columnar group, liquefaction based on the density increase effect, and ground improvement method for countermeasures against bearing capacity. 5. A plurality of holes are formed on the ground surface around the structure at an angle such as obliquely or horizontally in a sectional view directed downward of the structure, and the cylindrical forming is performed on the holes. The ground improvement method according to claim 4, wherein the body is charged and filled to form a columnar group. 6. The improvement effect in the ground can be made uniform by selectively arranging cylindrical moldings having different expansion performances in advance for a plurality of drillings having different angles, sizes, etc. in the ground. The ground improvement method according to claim 4 or 5, wherein: