JPH10311023A - Improvement method for foundation subsoil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a weak subsoil into a stable foundation subsoil by applying the constitution that a plurality of rows of vertical solidified walls reaching prescribed depth from ground surface are erected along one or two directions in a subsoil requiring an improvement at prescribed intervals, and a plurality of layers of horizontal solidified walls are constructed between the vertical solidified walls so as to be integrated therewith. SOLUTION: A plurality of rows of vertical solidified walls 1 are erected at prescribed intervals along one direction within a subsoil A likely to be subjected to liquefaction. Also, an upper horizontal solidified board 2a and a lower horizontal solidified board 2b are respectively laid between the upper ends of the vertical solidified walls 1 and 1 and between the lower ends thereof, so as to be integrated therewith. As a result, bearing capacity against a vertical load is increased, and the travel of underground water and the earth is prevented. At the same time, the transmission of excessive pore water pressure from a lower layer is intercepted. In this case, the arrangement, shape, depth, thickness or the like of the vertical solidified walls 1, the upper and the lower horizontal solidified boards 2a and 2b is determined on the basis of such a condition as an earthquake scale, subsoil strength or the like. For example, the vertical solidified walls 1 may be erected along two directions like plane grating. According to this construction, a subsoil likely to be subjected to liquefaction can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to improve a stable foundation ground in advance for use as a foundation ground of a building, for example, a sandy ground which may be liquefied, or a soft viscous ground which cannot escape consolidation settlement. The present invention relates to a method for improving a foundation ground for improving a soft ground requiring a ground into a hard stabilized ground.

[0002]

2. Description of the Related Art In sandy ground where there is a risk of liquefaction, or in softly viscous ground which is inevitable for long-term consolidation settlement, it is necessary to improve a stable ground in advance in order to use it as a foundation ground for buildings. As a method of improving the soft ground to a stable hard ground, for example, by injecting solidified milk such as cement into the ground that may be liquefied, stirring and mixing this solidified milk and excavated soil, The most commonly known method is to solidify the entirety of the ground that is likely to change.

[0003] Also, in the ground where there is a possibility of liquefaction, an underground continuous wall is constructed so as to surround only a portion where a building is to be constructed in a plane lattice shape or to block movement of groundwater and soil during an earthquake. There is also known a method of stabilizing the liquefied ground by using the method (see, for example, FIG. 14).

[0004] On the other hand, as a method of improving a soft viscous ground into a stable hard ground, a plurality of drains (waterways) made of sand piles and the like are installed in the ground, and forced drainage is performed through the drains to promote settlement. There is known a drain method for improving a supporting force.

On the other hand, the soft ground in the coastal and inland areas of Japan is composed of a layer of loose sand and volcanic ash on the upper side and a layer of soft clay and silt on the lower side. In many cases, it is necessary to take measures to prevent liquefaction of the upper sedimentary layer and to take measures to prevent consolidation settlement of the lower sedimentary layer.

[0006]

However, the method of solidifying the entire liquefied ground not only consumes a large amount of hardened material milk such as cement, but also improves the ground over a considerably wide range, so that the cost is reduced. However, there is a problem that the size is considerably increased.

[0007] A method of constructing an underground continuous wall in the ground where liquefaction is likely to occur and blocking the movement of groundwater and soil during an earthquake simply involves constructing the underground continuous wall to a certain depth from the ground surface. Therefore, transmission of excess pore water pressure from below is inevitable, and liquefaction may still occur below.

[0008] A method of constructing an underground continuous wall is to inject a solidified material milk such as cement into the ground which may be liquefied, and to stir and mix the solidified material milk and agitated soil to form a column. An underground continuous wall consisting of piles is constructed (see Fig. 15 (a)), and the ground that may be liquefied is penetrated and pulled out while rotating a stirring rod 31 equipped with stirring blades 30. At the same time, the solidified material milk is injected into the ground from the tip of the stirring rod 31 and is stirred with the surrounding excavated soil.
Mix to form a pillar stake (see Fig. 15 (b)). For this reason, especially when rotating the stirring rod 31 and penetrating into the ground, the stirring rod 31 penetrates into the ground while shaving the side surface of the solidified pile 32 constructed earlier, so that the stirring rod 31 has low resistance. (See Fig. 15 (b)), which causes the solidified pile 32 to bend in the depth direction and to be constructed, making it difficult to ensure the integrated construction and continuity of the underground continuous wall. .

[0009] On the other hand, the drain method using sand piles and the like aims to promote settlement in a short period of time and improve bearing capacity by forcibly draining water. There is a limit to the promotion and the improvement of the bearing capacity, so it will take a considerable period of time for the ground to be stable.

[0010] Further, as an improvement method for a soft ground comprising a liquefied layer and a soft clay layer, no particularly effective method has been developed so far.

The present invention has been made to solve the above problems, and can improve soft ground requiring ground improvement, such as liquified ground or soft viscous ground, into an extremely stable base ground. It is intended to provide a method for improving the foundation ground.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for improving a foundation ground according to the present invention is to provide a vertical solidification wall reaching a predetermined depth from the ground surface in a ground requiring ground improvement. Are formed in a plurality of rows at predetermined intervals in one direction or two directions, and a plurality of horizontal solidification plates are integrally formed at predetermined intervals between the vertically solidified walls.

A plurality of columnar solidification piles or intermediate vertical solidification walls which are integral with the horizontal solidification boards vertically adjacent to each other are constructed.

Further, between the vertical solidification wall and the horizontal solidification board,
A plurality of oblique solidification walls which are integral with these are constructed.

[0015] Further, between the lower ends of the adjacent vertically solidified walls,
A plurality of horizontal solidification braces that are integral with this are constructed, and between the horizontal solidification braces and the vertical solidification walls, a plurality of oblique solidification walls that are integral with these are constructed.

In the ground requiring ground improvement, a plurality of vertically solidified support piles or vertically solidified support walls or vertical solidified support piles integral with the vertical solidified wall, the horizontal solidified plate, or the horizontal solidified braces are constructed so as to reach the support ground.

In addition, the above-mentioned method involves injecting a stirring rod by high-pressure water injection and rotation, high-pressure injection of solidified material milk, and stirring and mixing of the solidified material milk and excavated soil into the ground requiring ground improvement. By repeatedly withdrawing the stirring rod, a vertically solidified wall composed of columnar solidified piles in the ground,
The horizontal solidification board, the diagonally solidified wall, the horizontal solidified brace, the vertical solidified support pile, and the vertical solidified support wall will be constructed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 of the Invention In the method for improving the foundation ground according to the present invention, for example, as shown in FIG. 1, a plurality of rows of vertically solidified walls 1 are formed at predetermined intervals in a direction A in a ground A where liquefaction is likely to occur. , 1 between the upper end and the lower end thereof, an upper horizontal solidification plate 2a and a lower horizontal solidification plate 2b, which are integral with the vertical solidification wall 1, respectively, are constructed, and as shown in FIGS. By constructing the columnar solidification pile 3 or the intermediate vertical solidification wall 4 integrally with the upper and lower horizontal solidification plates 2a and 2b between the solidification plate 2a and the lower horizontal solidification plate 2b, The purpose of the present invention is to stabilize the liquefied ground A by preventing the movement of groundwater and soil, and completely blocking the transmission of excess pore water pressure from below.

At the time of construction, an injection nozzle capable of injecting high-pressure water and solidified material milk at high pressure as shown in FIGS. 4 (a) and 4 (b), for example, to the ground A where there is a possibility of liquefaction. A stirring rod 31 provided with a stirring blade 31b capable of stirring and mixing the solidified milk and the excavated soil by rotating the stirring rod 31 while rotating high pressure water from the spray nozzle 31a to a predetermined depth. Penetrate it. Next, while injecting the solidified material milk at high pressure from the injection nozzle 31a, the stirring rod 31 is rotated to rotate the stirring blade 31b, and the solidified material milk and the excavated soil at the time of penetration are stirred and mixed by the stirring blade 31b. By gradually pulling out the stirring rod 31 while constructing a columnar solidification pile composed of the solidified material milk and the stirring soil in the ground A where there is a possibility of liquefaction, the columnar solidification inevitable by the conventional method It prevents the bending of piles, etc., and enables vertical construction of the columnar solidification piles. Further, the penetration and extraction of the stirring rods 31 are repeatedly performed, and the vertical solidification wall 1 composed of a number of columnar solidification piles and the upper and lower horizontal solidification boards 2a , 2b are integrated.

The arrangement, shape, depth, thickness, and the like of the vertical solidification wall 1, the upper horizontal solidification plate 2a, and the lower horizontal solidification plate 2b are determined by conditions such as the magnitude of the anticipated earthquake and the strength of the ground. For example, the vertically solidified wall 1 may be constructed in a plane lattice shape in two directions, and it is preferable to construct the vertically solidified wall 1 to a depth reaching the hard supporting ground because the supporting force of the vertical load is greatly increased.

The method of improving the foundation ground shown in FIG. 1 is suitable for improving the foundation ground of a relatively shallow ground having a depth of about 5 to 10 m, and the method of improving the foundation ground shown in FIGS. 1, and is particularly suitable for the improvement of the foundation ground requiring improvement over a wide range.

Embodiment 2 of the Invention 5 to 7 show another embodiment of the present invention. For example, as shown in FIG. 5, a plurality of rows of vertically solidified walls 1 are arranged at predetermined intervals in one direction in a ground A where there is a possibility of liquefaction. Build this vertically solidified wall 1,1
An upper horizontal solidification plate 2a, a lower horizontal solidification plate 2b, and an intermediate horizontal solidification plate 2c, which are integrated with the vertical solidification wall 1, are formed between the upper end portion, the lower end portion, and the intermediate portion, respectively. As shown in the figure, between the lower horizontal solidifying plate 2b and the intermediate horizontal solidifying plate 2c, or between the lower horizontal solidifying plate 2b and the intermediate horizontal solidifying plate 2c and between the intermediate horizontal solidifying plate 2c and the upper horizontal solidifying plate 2a. In both cases, a plurality of columnar solidification piles 3 integrally formed with these are constructed at predetermined intervals, and each is suitable for improvement of a foundation ground having a depth of 10 to 20 m or more.

Embodiment 3 of the Invention 8 to 11 show another embodiment of the present invention. For example, as shown in FIG. 8, a plurality of rows of vertically solidified walls 1 are arranged at predetermined intervals in one direction in a ground A where there is a possibility of liquefaction. Build this vertical solidified wall
An upper horizontal solidification plate 2a and a lower horizontal solidification plate 2b, which are integrated with the vertical solidification wall 1, between the upper end and the lower end of 1,1, respectively, and further have a soft viscosity lying below the ground A where there is a possibility of liquefaction. The columnar solidification support pile 5 or the vertical solidification support wall 6 that supports the underground structure composed of the vertical solidification wall 1 and the horizontal solidification board 2 integrally with the lower horizontal solidification board 2b in the ground B is rigidly supported. A plurality of structures are constructed so as to reach the ground 7, and as shown in FIG. 9, between the columnar solidification support piles 5,5 or between the vertical solidification support walls 6,6, a horizontal solidification jointing board 8, which is integral with them, is constructed. Further, as shown in FIGS. 10 and 11, between the upper horizontal solidification plate 2a and the lower horizontal solidification plate 2b, a columnar solidification pile 3 or a vertical solidification wall 4 which is integral with them is constructed. For example, if there is soft viscous ground that cannot escape consolidation settlement below the liquefied ground, It is suitable for improving poorly grounded ground.

Embodiment 4 of the Invention 12 and 13 show another embodiment of the present invention. For example, as shown in FIG. 12, a plurality of rows of vertically solidified walls 1 are arranged at predetermined intervals in one direction in a ground A where there is a possibility of liquefaction. Build this vertical solidified wall
An upper horizontal solidification plate 2a and a lower horizontal solidification plate 2b are respectively constructed between the upper end and the lower end of 1,1, and furthermore, a diagonal integrally formed between the vertical solidification wall 1 and the lower horizontal solidification plate 2b on both sides. By constructing the solidified walls 9 respectively, the inside defined by the diagonally solidified wall 9 and the upper and lower horizontal solidifying boards 2a and 2b is dug down from the ground in a substantially groove-shaped cross section to form the excavated portion 10, and the excavated portion 10 is formed. It is also possible to construct an underground structure (for example, a box culvert, etc.) in this area and use this underground structure as a common ditch for passing underground cables, sewers, and the like. In this case, since the diagonally solidified wall 9 can be used as an earth retaining wall when excavating the excavation portion 10, there is no need to provide an earth retaining wall, and labor saving and safe construction of the earth work can be performed.

Also, as shown in FIG.
An upper horizontal solidification board 2a and a plurality of horizontal solidification braces 11 are respectively constructed between the upper end portion and the lower end portion of 1,1, and are integrally formed between the vertical solidification walls 1 and the horizontal solidification braces 11 on both sides. The diagonally solidified wall 9 and the horizontal solidified bottom 12 are constructed, and then the inside partitioned by the diagonally solidified wall 9 and the horizontal solidified bottom 12 is dug down from the ground in a substantially groove-shaped cross section to form the excavated portion 10,
It is also possible to construct an underground structure (for example, a box culvert or the like) in the excavation unit 10 and use the underground structure as a common ditch for passing underground cables, sewers, and the like.

In this case, since the diagonal earth retaining wall 9 can be used as an earth retaining wall when excavating the excavation part 10, there is no need to provide an earth retaining wall, and labor saving and safe construction of the earth work can be performed. .

[0027]

The present invention has the above-described structure,
For example, in the ground that requires ground improvement such as sandy ground that may be liquefied, a plurality of vertical solidified walls reaching a predetermined depth from the ground surface are built in multiple rows at predetermined intervals in one or two directions, especially The movement of groundwater and soil can be reliably prevented, and the transmission of excess pore water pressure from below can be reliably blocked, and the liquefied ground can be stabilized.

When a soft viscous ground that cannot escape consolidation subsides lying below the sandy ground, a vertical solidification support united with a vertically solidified wall or a horizontal solidified ground is placed in the soft viscous ground. Since a plurality of piles or vertically solidified support walls are constructed so as to reach the support ground, a stabilized ground without consolidation settlement can be obtained.

Further, since an oblique solidification wall which is integral with the vertical solidification wall and the horizontal solidification wall is constructed between the adjacent vertical solidification wall and the horizontal solidification wall, the inside section defined by these portions is dug down from the ground into a substantially groove-shaped cross section to form the excavated portion. At the same time, an underground structure (for example, a box culvert, etc.) will be constructed in this excavation area, and this underground structure can be used as a common ditch for passing underground cables and sewers. Since it can be used as an earth retaining wall when excavating, there is no need to provide an earth retaining wall, and labor saving and safe construction of the earth work can be performed.

In addition, the above-mentioned method involves injecting a stirring rod by high-pressure water injection and rotation into the ground requiring ground improvement, high-pressure injection of solidified milk, and stirring and mixing of the solidified milk with excavated soil. By repeatedly pulling out the stirring rod, a vertical solidification wall consisting of a columnar solidification pile is constructed in the ground that requires soil improvement, and at this time, a part of the previously constructed columnar solidification pile is excavated. Since the stirring rod penetrates after being loosened with high-pressure water, it is possible to penetrate the stirring rod vertically, thereby preventing bending of the column-solidified pile, which cannot be avoided by the conventional method. Thus, integrated construction and continuity of a vertical solidification wall or a horizontal solidification board composed of a large number of columnar solidification piles can be achieved.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing the arrangement of a vertical solidification wall and an upper and lower horizontal solidification board.

FIG. 2 is a partial perspective view showing the arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a column row solidification pile.

FIG. 3 is a partial perspective view showing an arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a vertical solidification wall.

FIGS. 4A and 4B are longitudinal sectional views showing a construction method.

FIG. 5 is a partial perspective view showing the arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and an intermediate horizontal solidification wall.

FIG. 6 is a partial perspective view showing the arrangement of a vertical solidification wall, a vertical horizontal solidification board, an intermediate horizontal solidification wall, and a columnar solidification pile.

FIG. 7 is a partial perspective view showing an arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, an intermediate horizontal solidification wall, and a columnar solidification pile.

FIG. 8 is a partial perspective view showing the arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a column row solidification pile.

FIG. 9 is a partial perspective view showing the arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a column row solidification pile.

FIG. 10 is a partial perspective view showing the arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a column row solidification pile.

FIG. 11 is a partial perspective view showing an arrangement of a vertical solidification wall, an upper and lower horizontal solidification board, and a column row solidification pile.

FIG. 12 is a partial perspective view showing the arrangement of a vertical solidification wall, a horizontal solidification wall, an oblique solidification wall, and a horizontal solidification streak difference.

FIG. 13 is a partial perspective view showing an arrangement of a vertical solidification wall, a horizontal solidification wall, an oblique solidification wall, and a horizontal solidification streak difference.

FIG. 14 is a partial perspective view showing an example of a conventional arrangement of a vertically solidified wall.

15 (a) and (b) are a perspective view and a vertical sectional view showing an example of a conventional method of constructing a column-solidified pile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical solidified wall 2a Upper horizontal solidified wall 2b Lower horizontal solidified wall 2c Intermediate horizontal solidified wall 3 Pillar solidified pile 4 Pillar solidified wall 5 Vertical solidified support pile 6 Vertical solidified support wall 7 Supported ground 8 Horizontal solidified joint 9 Diagonal Solidified wall 10 Excavated part 11 Horizontal solidified bracing 12 Horizontal solidified bottom

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Haramoto 6-5-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Residential City Development Corporation Metropolitan Area Development Headquarters (72) Inventor Katsuo Kamada 6-5 Nishi-Shinjuku, Shinjuku-ku, Tokyo -1 Residential City Development Corporation Metropolitan Area Development Headquarters (72) Inventor Hiroshi Hayashi 2-9-1-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Corporation Technical Research Institute (72) Inventor Kenji Kato 1 Moto-Akasaka, Minato-ku, Tokyo 2-7-7 Kashima Construction Co., Ltd. (72) Inventor Ken Yamashita 4-51-5 Otacho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Kashima Construction Co., Ltd.Yokohama Branch (72) Inventor Michio Fujita Naka-ku, Yokohama-shi, Kanagawa Prefecture 4-51 Otacho Kashima Construction Co., Ltd. Yokohama Branch

Claims (6)

[Claims] 1. A plurality of vertical solidified walls reaching a predetermined depth from the surface of the ground at predetermined intervals in one or two directions in a ground requiring ground improvement, and are integrally formed between the vertical solidified walls. A method for improving the foundation ground, characterized in that a plurality of horizontal solidification plates forming a plurality of layers are formed at predetermined intervals. 2. A method of improving a foundation ground according to claim 1, wherein a plurality of columnar solidification piles or intermediate vertical solidification walls are formed integrally between the vertically solidified horizontal solidification piles. . 3. The method according to claim 1, wherein a plurality of diagonally solidified walls are formed integrally with the vertical solidified wall and the horizontal solidified wall. 4. A plurality of horizontal solidification braces which are integral with a lower end portion of an adjacent vertical solidification wall, and an oblique solidification wall which is integral with the horizontal solidification braces and the vertical solidification wall. The method for improving foundation ground according to claim 1, wherein a plurality of structures are constructed. 5. A plurality of vertically solidified support piles or vertically solidified support piles integral with a vertical solidification wall, a horizontal solidification board, or a horizontal solidification brace are constructed in a ground requiring ground improvement so as to reach the support ground. The method for improving the foundation ground according to any one of claims 1, 2, 3, and 4, wherein: 6. Involving penetration of a stirring rod by high-pressure water injection and rotation, high-pressure injection of solidified milk, and stirring and mixing of the solidified milk and excavated soil into the ground requiring ground improvement. By repeatedly pulling out the stirring rod, a vertical solidification wall, a horizontal solidification board, an oblique solidification wall, a horizontal solidification brace, a vertical solidification support pile, a vertical solidification support pile, and a vertical solidification support wall composed of columnar solidification piles are respectively constructed in the ground. The method for improving foundation ground according to any one of claims 1, 2, 3, 4, and 5, wherein: