JPH08326047A - Drain body for improving foundation - Google Patents

Abstract

PURPOSE: To improve the lower foundation of an existing structure by a method of construction using a solidifying material. CONSTITUTION: A drain body 1 for improving the foundation is composed by filling the inside of a cylindrical housing body 2 with a powdery solidifying material 3. The outside diameter of the drain body 1 is equalized approximately to the inside diameter of a specified casing penetrated into the foundation, to which foundation improvement is executed. The housing body 2 prevents the outflow of the solidifying material 3 on the inside before the drain body 1 for improving the foundation is inserted into the casing while having water permeability in an extent that water in the periphery is permeated to the inside after the casing is extracted, and may be formed of a water-permeable material such as paper, cloth, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement drain for use in soft ground improvement work.

[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 skeletons or particles is increased by means such as cementation, or pore water is removed to remove pores. A measure to reduce the volume is effective, but when removing pore water of cohesive soil, it is necessary to perform so-called consolidated drainage because of its low water permeability.

As such a ground improvement method, 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 consolidation is completed, In order to shorten the consolidation time in the construction method, it is common to build a sand pile in the ground beforehand, but as a construction method that does not require pre-loading, a construction method using a solidified material such as quick lime is known. ing.

In such a construction method, first, a predetermined casing is penetrated into the target soft ground to a predetermined depth, and then a solidifying material is charged and filled into the casing. Next, after airing the inside of the casing to a predetermined pressure, the casing is pulled out, and a column made of a solidifying material is formed in the soil.

When the solidifying material is press-fitted into the ground in a columnar manner as described above, the solidifying material reacts with pore water in the surrounding ground to generate hydrate crystals, and fixes the water in the soil. , The surrounding ground is loaded by the expansion effect accompanying the hydration reaction. Therefore, it is possible to forcibly dehydrate the pore water in the soft ground in a short period of time without requiring an overload.

[0006]

However, since such a solidifying material is in the form of powder, it is possible to put it in the vertical direction, but it is extremely difficult to put it in the casing arranged in the horizontal direction. Therefore, there is a problem that the ground improvement method using the solidifying material cannot be substantially adopted when the ground is to be improved below the existing structure.

The present invention has been made in consideration of the above-mentioned circumstances, and provides a ground improvement drainage body capable of adopting a construction method using a solidifying material even in the case of improving the ground below an existing structure. The purpose is to

[0008]

In order to achieve the above object, the ground improvement drain body of the present invention has an inner diameter of a predetermined casing penetrated into a target ground for ground improvement as described in claim 1. It has a substantially cylindrical shape having an outer diameter substantially equal to that of the above, and is filled with a powdery solidifying material in a predetermined container having water permeability.

The ground improvement drain body of the present invention is
The container according to claim 1 is made of a water-permeable material such as paper.

Further, the ground improvement drain body of the present invention is
The container according to claim 1 is made of a water-permeable or water-impermeable material having a large number of water passage holes.

Further, the ground improvement drain body of the present invention is
The container according to claim 1 is made of a material having water permeability and water absorbency.

Further, the ground improvement drain body of the present invention is
The cylindrical side surface of the container according to claim 1 is made of an impermeable material,
Both end surfaces of the container are made of a water-permeable material.

Further, the ground improvement drain body of the present invention is
A predetermined elastic body is attached to the cylindrical side surface of the container according to any one of claims 1 to 5.

[0014]

[Function] A predetermined casing is penetrated into the target ground in advance,
If there is residual soil in the casing, it is carried out, the ground improvement drain of the present invention is sequentially inserted into the casing, and finally the casing is pulled out and removed.

Then, the pore water contained in the surrounding ground is
It penetrates into the interior through the container for the ground improvement drain body. Then, it reacts with the solidifying material filled in the container to generate hydrate crystals and fix the water in the soil. In addition, the solidifying material breaks the surrounding container by the expansion action accompanying the hydration reaction and further loads the surrounding ground.

Here, when the above-mentioned container is made of a material having water permeability and water absorption, the water that initially enters is absorbed and held by the container and does not enter inside. Therefore, it is possible to prevent the residual water in the casing from reacting with the solidifying material immediately after inserting the ground improvement drain body into the casing.

When the cylindrical side surface of the container is made of a water impermeable material and both end surfaces of the container are made of a water permeable material, the pore water contained in the surrounding ground is the side surface of the container. Does not infiltrate, but only from the end face. Therefore,
The reaction rate of the solidifying material can be delayed by slowing the infiltration rate of water.

Further, when a predetermined elastic body is attached to the cylindrical side surface of the above-mentioned container, the elastic body expands to the periphery when the casing is pulled out, and comes into contact with the excavation hole. for that reason,
No void is formed between the excavated hole and the absorbing action of pore water proceeds smoothly.

[0019]

Embodiments of the ground improvement drain body of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is an overall perspective view of a ground improvement drain body according to the first embodiment, and FIGS.
It is the figure which showed the construction procedure which performs ground improvement using the ground improvement drain body.

As can be seen clearly in FIG. 1, the drain body 1 is constructed by filling a cylindrical container 2 with a powdered solidifying material 3, the outer diameter of which is the inside of the ground to be improved. The inner diameter of a predetermined casing that is inserted into

The container 2 prevents the solidifying material 3 from flowing out before the ground improvement drain 1 is inserted into the casing, and allows the surrounding water to permeate the inside after the casing is pulled out. It has a certain degree of water permeability, and is preferably made of a water permeable material such as paper or cloth. The solidifying material 3 may be cement-based or lime-based.

In order to improve the ground in the lower region of the existing structure 11 as shown in FIG. 2 (a) by using the ground improvement drain body 1 of the present embodiment, first, a casing, for example, a tip end, is placed in the target ground. The closed casing 12 is inserted horizontally. For the penetration, the working vertical shaft 4 is excavated in advance, and a shock is applied to the head of the casing 12 or the casing 12 is pressed in the vertical shaft 4.

Next, as shown in FIG. 2 (b), the casing 12 is replenished to a predetermined length by adding a necessary amount, and then the casing 12 shown in FIG.
As shown in (a), the ground improvement drain body 1 is sequentially inserted into the casing 12.

Next, as shown in FIG. 3 (b), the tip portion 13 of the casing 12 is opened on both sides and released to prepare for withdrawal of the casing.

Next, as shown in FIG. 3 (c), the jack 1
At 4, the casing 12 is pulled out and then removed. It is preferable to operate the jack 14 while pressing the back surface of the ground improvement drain body 1 with the pressing member 15 so that the ground improvement drain body 1 is not pulled out together with the casing 12 being pulled out.

When the ground improvement drain body 1 is arranged in the target ground in this way, pore water contained in the surrounding ground penetrates the inside through the container 2. Then, it reacts with the solidifying material 3 filled in the container 2 to generate hydrate crystals and fix the water in the soil. On the other hand, the solidifying material 3 breaks the surrounding container 2 by the expansion action associated with the hydration reaction to load the surrounding ground, and accelerates the consolidation drainage.

As described above, according to the ground improvement drain body of this embodiment, since the solidifying material is filled in the container in advance, the solidifying material is free-falled to remove the solidifying material. Unlike the conventional type that was put in the casing,
Even when the casing is penetrated in the horizontal direction, for example, the powdery solidifying material can be easily put into the casing.

Therefore, the ground improvement method using the solidifying material can be applied horizontally, and the method using the solidifying material should be applied even when there is an existing structure above the ground to be improved. You can

Further, dust will not fly up at the time of charging and the working environment will be improved.

In the present embodiment, the penetration direction of the casing is horizontal, but it is possible to select any direction as the penetration direction.
It may penetrate diagonally upward. Needless to say, it may be applied to normal vertical construction.

Further, in the present embodiment, an example in which the ground is improved by using the tip closed type casing has been described, but an open tip type casing may be used instead. Since the construction procedure for ground improvement using such a casing is almost the same as described above, a detailed explanation is omitted, but since the tip is open, it is necessary to separately take measures against water inflow. Will be supplementarily described below.

That is, as shown in FIG. 4 (a), an open-ended casing 21 is horizontally penetrated, and as shown in FIG. 4 (b), the casing 21 is replenished to have a predetermined length, and then the casing is opened. The remaining soil in 21 is discharged to the rear.

Next, as shown in FIG. 4 (c), a predetermined cap 23 is temporarily fixed to the tip of the rod 22, and is pushed into the casing 21 in this state to fix the cap 23 at the tip. Prevent water from flowing in. Further, if residual water is present in the casing 21, this is removed by air or the like. By this step, it is possible to prevent the reaction of the solidifying material before the removal of the casing 21.

The rest is almost the same as the casing of the tip closed type, and as shown in FIG. 5 (a), the ground improvement drain body 1
5 are sequentially inserted into the casing 21, and then, as shown in FIG. 5B, the jack 14 is operated while appropriately using the pressing member 15, and the casing 21 is pulled out and removed. The operation and effect of the ground improvement drain body when using the open-ended casing is almost the same as that of the closed-tip type, and therefore the description thereof is omitted here.

(Second Embodiment) Next, a second embodiment will be described. The parts and the like that are substantially the same as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

FIG. 6 (a) shows a ground improvement drain body 31 according to the second embodiment. As can be seen in the figure, the ground improvement drain body 31 is also similar to the above-described embodiment.
The solidified material 3 in the form of powder is filled in a cylindrical container 32 having an outer diameter similar to the inner diameter of the casing.
A large number of water passage holes 33 are formed on the side surface and both end surfaces of the container 32 of the present embodiment, and the pore water of the surrounding ground penetrates into the inside through the water passage holes 33. The container 32 may be a water-permeable material or a water-impermeable material. However, in the case of a water-permeable material, the infiltration of water due to the water-permeable effect of the material itself and the water-permeable effect of the water holes. You can increase the speed.

Ground improvement drain body 3 according to the second embodiment.
The construction procedure for ground improvement using No. 1 and the action and effect of the drain body at that time are almost the same as those in the above-described embodiment, and therefore detailed description thereof is omitted here.

(Third Embodiment) Next, a third embodiment will be described. Note that parts and the like substantially the same as those in the first or second embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 6 (b) shows a ground improvement drain body 41 according to the third embodiment. As can be seen from the figure, the ground improvement drain body 41 also has a cylindrical container 4 having an outer diameter similar to the inner diameter of the casing, as in the first embodiment.
2 is filled with the powdery solidifying material 3, but the container 42 of the present embodiment is made of a material having water permeability and water absorption such as corrugated paper and super absorbent resin. is there.

The construction procedure for ground improvement using the ground improvement drain body 41, and the action and effect of the drain body at that time are almost the same as those in the first embodiment, and therefore detailed description thereof is omitted here. However, in addition to these actions and effects, in the ground improvement drain body 41 of the present embodiment, the water that initially infiltrates is absorbed and held by the container 42 and does not infiltrate into the interior. Therefore, it is possible to prevent the residual water in the casing from reacting with the solidifying material 3 immediately after the ground improvement drain body 41 is inserted into the casing.

(Fourth Embodiment) Next, a fourth embodiment will be described. Note that parts and the like that are substantially the same as those in the first to third embodiments are assigned the same reference numerals and explanations thereof are omitted.

FIG. 7 (a) shows a ground improvement drain body 51 according to the fourth embodiment. As can be seen in the figure, the ground improvement drain body 51 also has a cylindrical container 5 having an outer diameter similar to the inner diameter of the casing, as in the first embodiment.
2 is filled with the powdered solidifying material 3, the container 52 of this embodiment has a cylindrical side surface 53 made of a water impermeable material, and both end surfaces 54 of the container 52 are It is made of water-permeable material.

The construction procedure for soil improvement using the soil improvement drain body 51, and the action and effect of the drain body at that time are almost the same as those in the first embodiment, and therefore detailed description thereof is omitted here. However, in addition to those actions and effects, in the ground improvement drain body 51 of the present embodiment, the pore water contained in the surrounding ground does not infiltrate from the side surface 53 of the containing body 51 and only from the end surface 54. Infiltrate. Therefore, the infiltration rate of water can be slowed to delay the reaction of the solidifying material 3.

(Fifth Embodiment) Next, a fifth embodiment will be described. Note that parts and the like that are substantially the same as those in the first to fourth embodiments are assigned the same reference numerals and explanations thereof are omitted.

FIG. 7B shows a ground improvement drain body 61 according to the fifth embodiment. As can be seen from the figure, the ground improvement drain body 61 is also a cylindrical container 2 having an outer diameter similar to the inner diameter of the casing, as in the first embodiment.
Although the powdery solidifying material 3 is filled in the interior, the ground improvement drain body 61 of this embodiment has an elastic body 62 attached to the cylindrical side surface of the container 2. As the elastic body 62,
A water-permeable material such as a sponge may be used, or a water-impermeable material such as a rubber sheet or a water-permeable material may be used.

The construction procedure for soil improvement using the soil improvement drain body 61 and the action and effect of the drain improvement body at that time are almost the same as those of the first embodiment, and therefore detailed description thereof is omitted here. However, in addition to these actions and effects, in the ground improvement drain body 61 of the present embodiment, the elastic body 62 is pulled out of the casing to release the restraint of the casing, and at the same time expands to the surroundings. Therefore, no void is formed between the excavation hole and the absorbing action of pore water smoothly proceeds.

[0048]

As described above, the ground improvement drain body of the present invention has a substantially cylindrical shape having an outer diameter approximately the same as the inner diameter of a predetermined casing penetrated into the target ground for ground improvement. Since a powdered solidifying material was filled in a predetermined container that is water-permeable, the ground improvement method using the powdery solidifying material will be adopted even at the site where there is an existing structure above. be able to.

[0049]

[Brief description of drawings]

FIG. 1 is an overall perspective view showing a ground improvement drain body according to a first embodiment with a part cut away.

FIG. 2 is an explanatory view showing a procedure for performing ground improvement using the ground improvement drain body according to the first embodiment.

FIG. 3 is an explanatory view showing a procedure for similarly performing ground improvement.

FIG. 4 is an explanatory view showing a ground improvement procedure when an open type casing is used instead of the closed type casing.

FIG. 5 is an explanatory diagram showing a procedure for similarly performing ground improvement.

6 (a) and 6 (b) are overall perspective views showing a ground improvement drain body according to a second embodiment and a third embodiment, with a part thereof being cut away.

7 (a) and 7 (b) are perspective views showing the whole ground improvement drain body according to the fourth and fifth embodiments with a part thereof cut away.

[Explanation of reference signs] 1 ground improvement drain body 2 container 3 solidifying material 12 tip closed type casing 21 tip open type casing 31, 41, 51, 61 ground improvement drain body 32, 42, 52 container 33 water passage hole 62 elastic body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Wada 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office

Claims (6)

[Claims] 1. A powder-like powder in a predetermined container having a substantially cylindrical shape having an outer diameter substantially equal to the inner diameter of a predetermined casing penetrating into the target ground for ground improvement and having water permeability. A ground improvement drain body characterized by being filled with a solidifying material. 2. The ground improvement drain body according to claim 1, wherein the container is made of a water-permeable material such as paper. 3. The ground improvement drain body according to claim 1, which is made of a water-permeable or water-impermeable material having a large number of water holes formed therein. 4. The ground improvement drain body according to claim 1, wherein the container is made of a material having water permeability and water absorption. 5. The ground improvement drain body according to claim 1, wherein a cylindrical side surface of the container is made of a water impermeable material, and both end surfaces of the container are made of a water permeable material. 6. The ground improvement drain body according to any one of claims 1 to 5, wherein a predetermined elastic body is attached to a cylindrical side surface of the container.