JP2913631B2 - Ground improvement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method suitable for improving soft ground, and more particularly to a ground improvement method using a drain body.

[0002]

2. Description of the Related Art In order to improve the stability of soil by improving soft ground mainly composed of cohesive soil, the resistance between frameworks or particles is increased by means such as cementation or the like, or pore water is removed by removing pore water. Although measures such as reducing the volume are effective, when removing pore water from cohesive soil, it is necessary to perform so-called consolidation drainage due to its low water permeability.

As such a ground improvement method, there is a so-called preloading method in which a load equivalent to or slightly larger than the load of a planned structure is placed on the ground, and the load is left until the consolidation is completed. In order to shorten the consolidation time in the construction method, it is common to construct a sand pile in the ground in advance, but as a construction method that does not require preloading, a construction method using solidified material such as quicklime is known. ing.

In such a construction method, first, a predetermined casing is penetrated into a target soft ground to a predetermined depth, and thereafter, a solidified material is charged and filled in the casing. Next, after evacuating the inside of the casing to a predetermined pressure, the casing is pulled out, and columns made of the solidified material are formed in the soil.

[0005] When the solidified material is pressed into the ground in the form of a column, the solidified material reacts with pore water in the surrounding ground to generate hydrate crystals, thereby fixing water in the soil. The surrounding ground is loaded by the expansion effect accompanying the hydration reaction. Therefore, the pore water in the soft ground can be forcibly dewatered in a short period of time without requiring an overload.

[0006]

However, since such a solidified material is in the form of a powder, it can be charged vertically, but it is very difficult to charge it into a horizontally disposed casing. Therefore, when the ground is improved below the existing structure, there has been a problem that the ground improvement method using the solidified material cannot be substantially adopted.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a ground improvement method that can use a solidified material even when the ground is improved below an existing structure.

[0008]

According to a first aspect of the present invention, there is provided a ground improvement method, wherein an open-end casing is penetrated into a target ground, and then the casing is opened. Out of the remaining soil, then insert a predetermined cap into the casing and attach it to the tip position, and then fill the powdery solidifying material in a water-permeable container with the drain body, The casing is inserted sequentially into the casing, and then the casing is pulled out and removed.

Further, the ground improvement method of the present invention is described in claim 1.
After attaching the cap in the above, the casing
To remove the water inside .

Further, according to the ground improvement method of the present invention, a working shaft is excavated in advance, and
Add the open-end casing to the existing structure
Horizontally, and then the remaining soil in the casing is carried out, and then a drain body constituted by filling a powdered solidifying material into a water-permeable container is sequentially inserted into the casing. Then, the casing is pulled out and removed.

Further, according to the ground improvement method of the present invention, a working shaft is excavated in advance and the
Add a closed-end casing to the existing structure while adding
Into the casing horizontally, and then a drain body constituted by filling a powdery solidifying material into a container having water permeability is sequentially inserted into the casing, and then the tip end of the casing is released. Thereafter, the casing is pulled out and removed.

[0012]

According to the ground improvement method of the present invention, the solidified material in the form of powder is not charged into the casing as it is as in the prior art, but is filled in the container in advance to form a drain, and the drain is inserted into the casing. Insert

After arranging the drain body in the target ground,
Pore water contained in the surrounding ground penetrates into the interior through the container. Then, it reacts with the solidifying material filled in the container to generate hydrate crystals, and fixes water in the soil. In addition, the solidified material breaks the surrounding container due to the expansion effect accompanying the hydration reaction, and further loads the surrounding ground.

In the case of using an open-end casing, before inserting the drain body, a predetermined cap is attached to the tip of the casing in advance, and water in the casing is removed by air or the like. To prevent the reaction of the solidified material.

When a casing with a closed end is used, the end of the casing is released before the casing is pulled out.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ground improvement method of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a flowchart showing an overall flow of a ground improvement method according to a first embodiment, and FIGS. 2 and 3 are diagrams showing construction procedures along the flow. FIG. 4 is an overall perspective view of a drain body used in the method.

In the ground improvement method of this embodiment, FIG.
As shown in (a), the area below the existing structure 1 is the target ground for ground improvement, and first, the casing 2 having an open end is horizontally penetrated into the target ground (FIG. 1, step 10).
1). When penetrating, the working shaft 31 is excavated in advance, and an impact is applied to the head of the casing 2 or the casing 2 is press-fitted in the shaft 31.

Next, the casing 2 is extended as needed to a predetermined length (FIG. 2 (b)), and then the remaining soil in the casing 2 is discharged backward (FIG. 1, step 1).
02).

Next, as shown in FIG. 2 (c), a predetermined cap 4 is temporarily fixed to the tip of the rod 3, and in this state, the cap 4 is pushed into the casing 2 to fix the cap 4 at the tip.
Water is prevented from flowing into the casing 2 (step 103 in FIG. 1). If there is residual water in the casing 2, it is removed by air or the like (step 104 in FIG. 1). By such a step, the reaction of the solidified material before the removal of the casing 2 can be prevented.

Next, as shown in FIG. 3 (a), the drain bodies 5 are sequentially inserted into the casing 2 (FIG. 1, step 1).
05). The drain body 5 has a cylindrical housing 1 having an outer diameter substantially equal to the inner diameter of the casing 2 as can be clearly seen in FIG.
1 is filled with a powdered solidifying material 12.

The container 11 prevents the solidified material 12 from flowing out before the drain body 5 is inserted into the casing 2 and has a degree that allows surrounding water to penetrate into the interior after the casing 2 is pulled out. And is preferably made of a water-permeable material such as paper or cloth. The solidifying material 12 may be a cement-based material or a lime-based material.

Next, as shown in FIG.
1, the casing 2 is pulled out and removed (FIG. 1,
Step 106). In order to prevent the drain body 5 from being pulled out at the same time as the casing 2 is pulled out, while holding the back surface of the drain body 5 with the holding member 22,
1 may be activated.

In this manner, the drain body 5 is placed in the target ground.
Is installed, the pore water contained in the surrounding ground
1 and penetrates into the inside of the drain body 5. Then, it reacts with the solidified material 12 filled in the container 11 to generate hydrate crystals and fix water in the soil. On the other hand, solidifying material 1
2 is a surrounding container 1 due to an expansion effect accompanying the hydration reaction.
Defeat 1 to load the surrounding ground and promote consolidation drainage.

As described above, according to the ground improvement method of this embodiment, the solidified material is filled in the container in advance to form a drain, and the drain is sequentially inserted into the casing. Unlike the conventional method in which the solidified material is thrown into the casing by free fall of the solidified material, even when the casing is penetrated in the horizontal direction, for example, the powdered solidified material is removed. It can be easily put into the casing.

Therefore, horizontal construction of the ground improvement method using the solidified material can be performed, and the method using the solidified material can be applied even when there is an existing structure above the ground to be improved. Can be.

Further, dust does not soar at the time of charging, and the working environment is improved.

In this embodiment, the casing penetrates in the horizontal direction. However, any direction can be selected for the penetrating direction.
It goes without saying that it may penetrate obliquely upward, or may penetrate vertically downward.

(Second Embodiment) Next, a second embodiment will be described. Note that the same reference numerals are given to components and the like that are substantially the same as those in the first embodiment, and description thereof will be omitted.

FIG. 5 is a flowchart showing the overall flow of the ground improvement method according to the second embodiment, and FIGS.
It is a figure showing a construction procedure along such a flow.

In the ground improvement method of the present embodiment, FIG.
The area below the existing structure 1 shown in (a) is a target ground for ground improvement, and first, a casing 41 having a closed end is horizontally penetrated into the target ground (FIG. 5, step 11).
1). Unlike the first embodiment using the open-end type casing, the earth and sand do not remain in the casing, so that the step of carrying out the earth and sand is omitted in this embodiment.

Next, as shown in FIG. 6 (b), the casing 41 is added to the required length to obtain a predetermined length.
As shown in (a), the drain bodies 5 are sequentially inserted into the casing 41 (FIG. 5, step 112). Unlike the first embodiment using the open-end casing, since there is no possibility that water flows from the tip of the casing, the step of attaching a cap to the tip of the casing and the step of removing water from the casing are performed in this manner. It is omitted in the embodiment.

Next, as shown in FIG. 7 (b), the distal end portion 42 of the casing 41 is opened and opened on both sides (FIG. 5, step 113) to prepare for pulling out of the casing.

Next, as shown in FIG.
1, the casing 41 is pulled out and removed (step 114 in FIG. 5). It is preferable that the jack 21 be operated while the back surface of the drain body 5 is pressed by the pressing member 22 so that the drain body 5 is not pulled out together with the removal of the casing 41.

In this way, the drain body 5 is placed in the target ground.
Is disposed, the pore water contained in the surrounding ground penetrates into the drain body 5 through the housing 11 as in the first embodiment. Then, the solidified material 1 filled in the container 11
Reacts with 2 to generate hydrate crystals and fix the water in the soil. On the other hand, the solidified material 12 breaks the surrounding container 11 by the expansion action accompanying the hydration reaction, and loads the surrounding ground, thereby promoting consolidation drainage.

As described above, in the ground improvement method of the present embodiment, similarly to the first embodiment, a solidified material is filled in the container in advance to form a drain, and the drain is sequentially inserted into the casing. Thus, unlike the conventional method in which the solidified material in a powder state is dropped into the casing by free fall of the solidified material, even if the casing is penetrated in the horizontal direction, for example, The solidified material can be easily put into the casing.

Therefore, horizontal construction of the ground improvement method using the solidified material becomes possible, and the method using the solidified material is applied even when there is an existing structure above the ground to be ground-improved. Can be. In addition, dust does not soar at the time of charging, and the working environment is improved.

In this embodiment as well, any direction can be selected as the direction of penetration, and depending on the situation at the site, it may penetrate diagonally downward, diagonally upward, or vertically downward. It goes without saying that it may penetrate.

[0039]

As described above, according to the ground improvement method of the present invention according to claims 1 and 2, pore water contained in the surrounding ground reacts with the solidifying material to form hydrate crystals. In addition to the effect of generating and fixing the water in the soil, the expansion effect caused by the hydration reaction causes the solidified material to break the surrounding container and load the surrounding ground, and in addition, the inflow of water into the casing This has the effect of preventing the reaction of the solidified material before removing the casing.

Further, according to the soil improvement method of the present invention according to the third and fourth aspects, pore water contained in the surrounding ground reacts with the solidifying material to generate hydrate crystals, and water in the soil is formed. In addition to the effect of the solidification material breaking the surrounding container due to the expansion effect due to the hydration reaction and loading the surrounding ground, the horizontal construction of the ground improvement method using the solidification material becomes possible In addition, even when there is an existing structure above the ground to be improved, the effect of applying the method using the solidifying material can be obtained.

[0041]

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of a ground improvement method according to a first embodiment.

FIG. 2 is an explanatory diagram showing a construction procedure of a ground improvement method according to the first embodiment.

FIG. 3 is an explanatory view showing a construction procedure.

FIG. 4 is an overall perspective view showing a drain body used in the method.

FIG. 5 is a flowchart showing a flow of a ground improvement method according to a second embodiment.

FIG. 6 is an explanatory diagram showing a construction procedure of a ground improvement method according to a second embodiment.

FIG. 7 is an explanatory view showing a construction procedure.

[Explanation of symbols]

 101, 111 Casing penetrating process 102 Residual soil unloading process 103 Cap attaching process 105, 112 Drain body inserting process 113 Casing tip releasing process 106, 114 Casing pulling-out removing process 1 Existing structure 2 Tip-opening casing 4 Cap 5 Drain body 11 Container 12 Solidification material

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Wada 2-3-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office (56) References JP-A-49-56413 (JP, A) JP-A Sho 49-82117 (JP, A) JP-A-49-82118 (JP, A) JP-A-59-88525 (JP, A) JP-A-62-38944 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 3/10 104

Claims (4)

(57) [Claims] 1. An open-end casing penetrates into the target ground, then unloads the remaining soil in the casing, inserts a predetermined cap into the casing and attaches it to the tip position, A ground improvement method characterized by sequentially inserting a drain body constituted by filling a powdery solidifying material into a water-permeable container into the casing, and then pulling out and removing the casing. 2. After the cap is attached, the case
The soil improvement method according to claim 1 , wherein water in the shing is removed . 3. A working shaft is excavated in advance, and a connection is established in the shaft.
While opening the casing, open the tip of the casing below the existing structure.
Horizontally penetrates the region , then unloads the remaining soil in the casing, and then sequentially inserts a drain body configured by filling a powdered solidifying material into a water-permeable container, into the casing, Next, a ground improvement method, wherein the casing is pulled out and removed. 4. A working shaft is excavated in advance, and is connected in the shaft.
While closing, add a closed-end casing below the existing structure.
After horizontally penetrating into the region, and then sequentially inserting a drain body constituted by filling a powdery solidifying material into a container having water permeability into the casing, and then releasing the tip of the casing, A ground improvement method, wherein the casing is pulled out and removed.