JP7009889B2 - Ground improvement body and construction method of ground improvement body - Google Patents

Description

The present invention relates to a ground improvement body formed by a plurality of pillars and a method of constructing the ground improvement body.

Patent Document 1 discloses a technique for forming a ground restraint wall made of a ground improvement body in the ground to prevent liquefaction of the ground. The ground improvement body is formed by injecting a solidifying agent such as cement milk into the excavated soil while excavating the ground and stirring and mixing. The ground improvement body has a cylindrical shape. A plurality of ground improvement bodies are arranged so as to partially overlap each other in the radial direction.

Japanese Unexamined Patent Publication No. 2015-161565

The smaller the distance between the centers of two adjacent prisms and the larger the overlapping portion of the two prisms, the stronger the coupling force between the two prisms. However, the total volume of the prisms (number of prisms x volume of prisms) increases. Then, the amount of the solidifying agent used for forming the prism increases, and the manufacturing cost increases. By increasing the distance between two adjacent prisms and reducing the overlap, the amount of solidifying agent used can be reduced. However, the coupling force between the two prisms is weakened. If the bonding force between the prisms is weak, there is a risk that the prisms will separate from each other when a shearing force acts between the prisms due to an earthquake or the like.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a means capable of reducing the amount of a solidifying agent used while maintaining the bonding force between prisms equal to or higher than the conventional one. It is in.

(1) The ground improvement body according to the present invention is a structure in which a plurality of columnar pillars having a vertical direction as an axial direction are continuously arranged in the radial direction in the ground, and a structure separated in the radial direction. It has one end and a second end, and includes a reinforcing member extending in the vertical direction. The first end and the second end of the reinforcing member are inserted into two adjacent pillars, respectively.

Since the first end and the second end of the reinforcing member are inserted into two adjacent columns, the bonding force between the two adjacent columns can be enhanced. Therefore, the diameter of the prism can be made smaller than before while maintaining the coupling force between the two adjacent prisms, or the distance between the centers between the two adjacent prisms can be made larger than before. be able to. As a result, it is possible to reduce the amount of the solidifying agent used while maintaining the bonding force between two adjacent columns equal to or higher than the conventional one.

(2) Preferably, the two adjacent prisms may be separated from each other in the radial direction.

Since the two adjacent prisms are separated from each other in the radial direction, the amount of the solidifying agent used can be reduced as compared with the case where the two adjacent prisms are partially overlapped in the radial direction.

(3) Preferably, the two adjacent prisms may partially overlap in the radial direction. The reinforcing member is inserted at least in the overlapping portion of the prism.

Since the two adjacent prisms partially overlap in the radial direction and the reinforcing member is inserted at least in the overlapping portion of the prisms, the two adjacent prisms are arranged apart from each other in the radial direction. It is possible to increase the cohesive force between the prisms rather than doing so.

(4) Preferably, the outer peripheral surfaces of the two adjacent prisms may be in contact with each other in the radial direction.

The outer peripheral surfaces of the two adjacent prisms are in contact with each other in the radial direction. The reinforcing member is inserted into the ground so as to overlap both of the two adjacent prisms before the prism solidifies. Since the outer peripheral surfaces of the two adjacent prisms are in contact with each other in the radial direction, it is easier to provide a reinforcing member in the ground than to completely separate the two adjacent prisms while separating the two adjacent prisms. Can be inserted into. That is, it is possible to ensure the ease of construction of the ground improvement body while reducing the amount of the solidifying agent used.

(5) The method of constructing the ground improvement body according to the present invention is a structure in which a plurality of columnar columns whose axial direction is the vertical direction are continuously arranged in the radial direction in the ground and the above-mentioned radial direction. It has a first end and a second end separated from each other, and the first end and the second end are inserted into two adjacent pillars, respectively, and have a reinforcing member extending in the vertical direction. It is a construction method of the ground improvement body. The construction method includes the first step of forming the pillar in the ground by mixing a solidifying agent into the excavated soil while excavating the ground, and the reinforcing member in the ground before the pillar is solidified. It has a second step of inserting into.

The present invention can also be regarded as a method of constructing a ground improvement body.

According to the ground improvement body and the construction method of the ground improvement body according to the present invention, it is possible to reduce the amount of the solidifying agent used while maintaining the bonding force between the columns.

FIG. 1 is a plan view of the ground improvement body 20 according to the embodiment. FIG. 2 is a perspective view of the ground improvement body 20. FIG. 3A is a plan view of the ground improvement body 20 according to the embodiment, and FIG. 3B is a plan view of the conventional ground improvement body 40. 4 (A) is a perspective view of the ground improvement body 20 according to the modified example 1, FIG. 4 (B) is a perspective view of the ground improved body 20 according to the modified example 2, and FIG. 4 (C) is a perspective view. It is a perspective view of the ground improvement body 20 which concerns on the modification 3. FIG. 5 is a perspective view of the reinforcing members 32, 33, and 34 according to the modified example 4. FIG. 6A is a diagram showing a construction method 50 of the ground improvement body 20 according to the embodiment, and FIG. 6B is a diagram showing a construction method 60 of the ground improvement body 20 according to the modified example 5. ..

Hereinafter, embodiments of the present invention will be described. It is needless to say that the embodiments described below are merely examples of the present invention, and the embodiments of the present invention can be appropriately changed without changing the gist of the present invention.

In this embodiment, the basic structure 10 shown in FIG. 1 will be described. The foundation structure 10 includes a ground improvement body 20 shown by a solid line and a foundation 11 shown by a two-dot chain line. The foundation 11 is a cloth foundation or a solid foundation, and supports the frame of a building (not shown). The building is, for example, a house.

The ground improvement body 20 includes a plurality of pillar bodies 21. Although details will be described later, the prism 21 is formed by using a construction machine (not shown). As the construction machine, for example, a pile driver such as DHJ60 or DHJ85 of Nippon Sharyo Co., Ltd. (trademark) is used.

The construction machine includes a rod (pile) and an auger drill provided at the tip of the rod. The auger drill excavates the ground while rotating and is inserted into the ground. The rod has a spout from which a solidifying agent such as cement milk is ejected. The rod also has a stirring blade that mixes the excavated soil with the injected solidifying agent. When the solidifying agent solidifies, a columnar prism 21 is formed in the ground as shown in FIG.

The formed pillar 21 is a vertically long columnar body long in the vertical direction 13 with the vertical direction 13 as the axial direction. The length of the pillar 21 in the vertical direction 13 is determined according to the length of the rod of the construction machine. The length of the prism 21 is set to, for example, 10 to 15 m. Further, the diameter of the pillar 21 is determined according to the shape of the auger drill. The diameter of the pillar 21 is set to, for example, 40 cm to 80 cm. Specifically, it is set to 50 cm, 55 cm or 65 cm.

The plurality of prisms 21 are formed side by side along the radial direction 14 with some of them overlapping each other. As shown in FIG. 1, the plurality of prisms 21 form a structure 23 having a frame shape in a plan view.

As shown in FIG. 2, the reinforcing member 30 is arranged in the overlapping portion 22 where two adjacent prisms 21 overlap.

The reinforcing member 30 is a rectangular flat plate having a longitudinal direction 13 in the vertical direction and a short side in the radial direction 14. The reinforcing member 30 is arranged on a virtual straight line (not shown) connecting the centers of the two adjacent pillars 21 at the overlapping portion 22 of the two adjacent pillars 21, and is inserted into the two pillars 21, respectively. Has been done. The reinforcing member 30 provided in this way enhances the coupling force between the two adjacent columns 21.

The reinforcing member 30 is inserted into the ground by the above-mentioned construction machine. The construction machine grips one end (upper end) of the reinforcing member 30 in the longitudinal direction to suspend the reinforcing member 30, and presses the upper end of the reinforcing member 30 downward to insert the reinforcing member 30 into the ground. The reinforcing member 30 is inserted into the ground until the solidifying agent hardens.

The material and thickness of the reinforcing member 30 are set so that the reinforcing member 30 can be inserted into the ground and can withstand a load (shearing force) applied to the ground improvement body 20 due to an earthquake or the like. For example, a steel material having a thickness of several mm to a dozen mm is used for the reinforcing member 30.

The length of the pillar 21 in the vertical direction 13 is substantially the same as or shorter than the length of the pillar 21 in the vertical direction 13. That is, the reinforcing member 30 does not go beyond the pillar 21 and is inserted into the ground. Therefore, the reinforcing member 30 can be easily inserted into the ground by using a construction machine.

Further, the length of the reinforcing member 30 in the vertical direction 13 is preferably half or more of the length of the pillar 21 in the vertical direction 13. Therefore, the reinforcing member 30 can reliably connect the two prisms 21. Further, more preferably, the length of the reinforcing member 30 in the vertical direction 13 is substantially the same as the length of the pillar 21 in the vertical direction 13. By making the length of the reinforcing member 30 in the vertical direction 13 substantially the same as the length of the pillar 21 in the vertical direction 13, the coupling force between the two pillars 21 can be further enhanced.

Since the reinforcing member 30 is arranged in the overlapping portion 22, one end (first end of the present invention) of the reinforcing member 30 in the direction along the short side (diametrical direction of the pillar 21) is one of the pillars. It is inserted into 21 and the other end (second end of the present invention) of the reinforcing member 30 is inserted into the other pillar 21.

The distance L1 between the two adjacent pillars 21 shown in FIG. 3A is made larger than the distance L2 between the pillars 21 of the conventional ground improvement body 40 shown in FIG. 3B. The configuration of the prism 21 shown in FIG. 3 (A) is the same as the configuration of the prism 21 shown in FIG. 3 (B).

The distance L1 is, for example, 50 cm, and the distance L2 is, for example, 40 cm. When the distance L1 is 50 cm and the distance L2 is 40 cm, the amount of the solidifying agent used in the ground improvement body 20 is 20% less than before.

On the other hand, a reinforcing member 30 is arranged at the overlapping portion 22 of the two prisms 21 shown in FIG. 3 (A), and the coupling force between the prisms 21 is the conventional one shown in FIG. 3 (B). It is equal to or higher than the bonding force between the prisms 21.

[Construction method 50 of ground improvement body 20]
The construction method 50 shown in FIG. 6A includes a first step 51 of forming a pillar 21 using a construction machine and a second step 52 of inserting a reinforcing member 30 into the ground using the same construction machine. To prepare for. The first step 51 and the second step 52 are repeatedly executed.

More specifically, first, in the first step 51, the operator excavates the ground using the above-mentioned construction machine, injects a solidifying agent into the excavated soil, and stirs the excavated soil to form the pillar 21. The worker first forms several pillars 21.

Next, in the second step 52, the worker inserts the reinforcing member 30 into the ground using the construction machine used for excavation. The operator inserts the reinforcing member 30 into the ground until the solidifying agent hardens. That is, the operator forms in the first step 51 the number of pillars 21 that allows the reinforcing member 30 to be inserted into the ground before the solidifying agent hardens.

The worker repeats the first step 51 and the second step 52 to form the ground improvement body 20 in the ground.

After forming the ground improvement body 20 in the ground, the worker installs the foundation 11 (FIG. 1) on the ground improvement body 20. After the foundation 11 is provided, the worker builds a building (not shown) on the foundation 11.

[Effect of embodiment]
Since the reinforcing member 30 is arranged at the overlapping portion 22 of the two adjacent pillars 21 and inserted into each of the two adjacent pillars 21, it is possible to increase the coupling force between the two adjacent pillars 21. can. Therefore, as shown in FIG. 3, the distance between the centers of the two adjacent prisms 21 can be made larger than before while maintaining the coupling force between the two adjacent prisms 21. As a result, it is possible to reduce the amount of the solidifying agent used while maintaining the bonding force between the two adjacent pillars 21 at the same level as or higher than the conventional one.

Further, since the reinforcing member 30 is a flat plate, the resistance received when it is inserted into the ground is lower than that of a cylinder or a prism. Therefore, the reinforcing member 30 can be easily inserted into the ground by using a construction machine.

Further, since the length of the reinforcing member 30 in the vertical direction 13 is substantially the same as or shorter than the length of the pillar 21 in the vertical direction 13, the reinforcing member 30 may be inserted into the ground beyond the pillar 21. do not have. Therefore, the reinforcing member 30 can be inserted into the ground without being damaged.

Further, since the length of the reinforcing member 30 in the vertical direction 13 is more than half the length of the pillar 21 in the vertical direction 13, two adjacent pillars 21 can be reliably connected.

Further, since the foundation 11 (FIG. 1) is provided on the ground improvement body 20, the foundation 11 can be reliably supported by the ground improvement body 20.

Further, in the construction method 50 of the ground improvement body 20, the pillar body 21 is formed by one construction machine, and the reinforcing member 30 is inserted into the ground. The construction method 50 is used at a construction site where only one construction machine can be carried in. Since the ground improvement body 20 is constructed by one construction machine, the ground improvement body 20 can be constructed even when the site (construction site) where the foundation structure 10 (FIG. 1) is to be constructed is small. ..

Further, since the ground improvement body 20 is constructed by one construction machine, the construction cost can be suppressed as compared with the case where a plurality of construction machines are used.

[Modification 1]
In the above-described embodiment, an example in which the reinforcing member 30 (FIG. 2) is arranged at the overlapping portion 22 of two adjacent prisms 21 has been described. In the first modification, as shown in FIG. 4A, an example in which the reinforcing member 31 is provided beyond the overlapping portion 22 of the two prisms 21 will be described.

The length of the reinforcing member 31 is longer than that of the reinforcing member 30. The central portion of the reinforcing member 31 in the direction along the short side (diameter direction 14) is located at the overlapping portion 22, and both end portions of the reinforcing member 31 in the direction along the short side are located outside the overlapping portion 22.

[Effect of variant 1]
Since the reinforcing member 31 is provided beyond the overlapping portion 22 of the two pillars 21, the bonding force between the two adjacent pillars 21 can be further enhanced.

[Modification 2]
In the above-described embodiment, an example in which a part of two adjacent prisms 21 overlap each other has been described. In this modification, as shown in FIG. 4B, an example in which the outer peripheral surfaces of two adjacent pillars 21 are in contact with each other will be described.

The reinforcing member 30 has the same configuration as the reinforcing member 30 described in the first embodiment. The reinforcing member 30 is arranged on a virtual straight line (not shown) connecting the centers of two adjacent pillars 21, and is inserted into each of the two pillars 21. The reinforcing member 30 inserted into each of the two adjacent prisms 21 enhances the bonding force between the two prisms 21.

[Effect of variant 2]
In this modification, the outer peripheral surfaces of two adjacent pillars 21 are in contact with each other. Therefore, the distance between two adjacent prisms 21 is larger than that of the above-described embodiment having the overlapping portion 22. As a result, the amount of the solidifying agent used is smaller than that in the embodiment. On the other hand, the reinforcing member 30 maintains the bonding force between the two adjacent columns 21 at the same level as or higher than the conventional one.

[Modification 3]
In the above-described embodiment, an example in which a part of two adjacent prisms 21 overlap each other has been described. In this modification, as shown in FIG. 4C, an example in which two adjacent prisms 21 are separated from each other will be described.

The reinforcing member 31 has the same configuration as the reinforcing member 31 described in the first modification. One end (first end) of the reinforcing member 31 in the direction along the short side is inserted into one of the two prisms 21 adjacent to each other, and the other end (second end) is inserted into the other pillar 21. Has been done. The reinforcing member 31 having an end inserted into each of the two separated columns 21 connects the two separated columns 21.

[Effect of variant 3]
In this modification, two adjacent prisms 21 are separated from each other. Therefore, the distance between two adjacent prisms 21 is larger than that of the above-described embodiment having the overlapping portion 22. As a result, the amount of the solidifying agent used is smaller than that in the embodiment. On the other hand, the reinforcing member 31 is connected to the two pillars 21 which are separated from each other, and the coupling force between the two adjacent pillars 21 is maintained at the same level as or higher than the conventional one.

[Modification 4]
In the above-described embodiments and modifications 1 to 3, examples in which the reinforcing members 30 and 31 which are flat plates are used have been described. However, the reinforcing member 32 may be used instead of the reinforcing members 30 and 31. As shown in FIG. 5A, the reinforcing member 32 is a corrugated plate having a wavy cross section along a horizontal plane.

Further, the reinforcing member 33 may be used instead of the reinforcing members 30 and 31. As shown in FIG. 5B, the reinforcing member 33 has a cross-shaped cross section along the horizontal plane.

Further, the reinforcing member 34 may be used instead of the reinforcing members 30 and 31. The reinforcing member 34 is a cylinder as shown in FIG. 5 (C).

Further, instead of the reinforcing members 30 and 31, a striped steel plate (not shown) having protrusions (stripes) on the front surface or the back surface of the flat plate may be used.

[Action and effect of variant 4]
When the reinforcing member 32 which is a corrugated plate is used, the strength is higher than that of a flat plate, and the resistance when the reinforcing member 32 is inserted into the ground is lower than that of a cylindrical shape or a prismatic shape. That is, the bonding force between the two pillars 21 is increased, and the reinforcing member 32 can be easily inserted into the ground.

When the reinforcing member 33 having a cross shape is used, the strength is higher than that of a flat plate or a corrugated plate, and the resistance when the reinforcing member 33 is inserted into the ground is higher than that of a cylindrical shape or a prismatic shape. Low. That is, the bonding force between the two pillars 21 is increased, and the reinforcing member 33 can be easily inserted into the ground.

When the reinforcing member 34 which is a cylinder is used, the strength is higher than the shape of a flat plate, a corrugated plate, or a cross, and the resistance when the reinforcing member 34 is inserted into the ground becomes cylindrical or prismatic. Low compared to. That is, the bonding force between the two pillars 21 is increased, and the reinforcing member 34 can be easily inserted into the ground.

When a reinforcing member (not shown) which is a striped steel plate is used, the strength is higher than that of a flat plate, and the resistance when the reinforcing member is inserted into the ground is lower than that of a cylinder or a prism. That is, the bonding force between the two pillars 21 is increased, and the reinforcing member can be easily inserted into the ground.

[Modification 5]
In the above-described embodiment, the construction method 50 for forming the ground improvement body 20 using one construction machine has been described. In the present modification 5, a construction method 60 for forming the ground improvement body 20 using two construction machines will be described.

As shown in FIG. 6B, the construction method 60 of the ground improvement body 20 described in this modification is the first step 61 for forming the pillar 21 using the first construction machine and the second construction. A second step 62 for inserting the reinforcing member 30 into the ground using a machine is provided. The first step 51 and the second step 52 are performed in parallel.

To explain in detail, first, in the first step 61, the worker excavates the ground using the first construction machine, injects a solidifying agent into the excavated soil, and stirs to form the pillar 21. The worker continuously forms the prism 21.

On the other hand, another worker inserts the reinforcing member 30 into the ground by using the second construction machine in the second step 62. The other worker continuously inserts the reinforcing member 30 into the ground before the solidifying agent solidifies.

[Action and effect of variant 5]
The construction method 60 of this modification is performed at a site (construction site) where two or more construction machines can be carried in. Since the first construction machine only needs to form the pillar 21 and the second construction machine only needs to insert the reinforcing member 30, the work efficiency of the construction is improved.

[Other variants]
In the above-described embodiment and modification, as shown in FIG. 3, an example is described in which the distance between two adjacent prisms 21 is made larger than before to reduce the amount of the solidifying agent used. However, the diameter of the column 21 may be made smaller than before to reduce the amount of the solidifying agent used.

10 ... Foundation structure 11 ... Foundation 20 ... Ground improvement body 21 ... Pillar body 22 ... Overlapping part 23 ... Structure 30, 31, 32, 33, 34 ... Reinforcing member 50, 60 ... Construction method of ground improvement body 51, 61 ... First step 52, 62 ... Second step

Claims (3)

It supports the foundation of a house, and a plurality of pillars formed in a columnar shape in the vertical direction by mixing excavated soil and a solidifying agent in the ground are continuously arranged in the radial direction. Structure and
It has a first end and a second end separated in the radial direction, and the first end and the second end are inserted into the two adjacent prisms, respectively, and the reinforcing member extends in the vertical direction. , Equipped with,
In the prism, two adjacent prisms are separated from each other in the radial direction.
The reinforcing member is a flat plate arranged along a virtual straight line connecting the centers of adjacent pillars, and the length along the virtual straight line is shorter than the radius of the pillars . It supports the foundation of a house, and a plurality of pillars formed in a columnar shape in the vertical direction by mixing excavated soil and a solidifying agent in the ground are continuously arranged in the radial direction. Structure and
It has a first end and a second end separated in the radial direction, and the first end and the second end are inserted into the two adjacent prisms, respectively, and the reinforcing member extends in the vertical direction. , Equipped with,
The prisms partially overlap in the radial direction so that the distance between two adjacent centers is longer than the radius of the prisms.
The reinforcing member is a flat plate arranged between the centers of the adjacent pillars along a virtual straight line connecting the centers of the adjacent pillars, and is inserted into the overlapping portion of the pillars. Ground improvement body . It supports the foundation of a house, and a plurality of pillars formed in a columnar shape in the vertical direction by mixing excavated soil and a solidifying agent in the ground are continuously arranged in the radial direction. Structure and
It has a first end and a second end separated in the radial direction, and the first end and the second end are inserted into the two adjacent prisms, respectively, and the reinforcing member extends in the vertical direction. , Equipped with,
In the prism, two adjacent outer peripheral surfaces are in contact with each other in the radial direction.
The reinforcing member is a flat plate arranged between the centers of the adjacent pillars along a virtual straight line connecting the centers of the adjacent pillars, and the length along the virtual straight line is the above. A ground improvement body shorter than the diameter of the prism.

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