JP2009052249A - Construction method of storage tank in base rock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently place and fill back-filling concrete on the back face side without deforming a lining material forming an airtight container in a storage tank in a base rock. <P>SOLUTION: In placing and filling the back-filling concrete in a filling space on the back face side of the airtight container 2 stepwise from its bottom part toward its top part, storage water W is injected in the airtight container, and its water level WL is maintained in a higher position than a concrete placement predetermined top end of a following stage. In this state, a following stage concrete placing process is carried out in the air, and a final stage concrete placing process to the topmost part in the filling space is carried out in a full water state in the airtight container. A filling pipe and a return pipe for pressurizing and injecting a grout material into the topmost part of the filling space are arranged beforehand, and the grout material is further pressurized and injected after concrete placement to the topmost part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an in-rock storage facility for storing high-pressure gas or low-temperature liquefied gas in a cavity provided in the rock, and in particular, a lining-type in-rock storage tank in which an airtight container made of a lining material is provided in the cavity. It relates to a method for construction.
In the bedrock storage facility for storing low-temperature liquefied gas, a membrane material is used as a material for ensuring liquid-tight performance and air-tight performance, but both the membrane material and the lining material are functionally similar. In this specification, the lining material including the membrane material is collectively referred to as a lining material storage tank.

This type of lining-type storage tank in rock mass secures the pressure resistance performance against the internal pressure by the surrounding rock mass, and the airtight container and the liquid-tight performance required for the storage tank (tank) are secured by an airtight container formed of lining material. One example is shown in FIG.
This is because an airtight container 2 is formed in the cavity 1 by excavating a cavity 1 shaped like a horizontal egg in the bedrock and covering the inner surface with a lining material, and the surface of the cavity 1 and the airtight container 2 are formed. A back-filled concrete 3 is placed between the back and the back of the container to support the airtight container 2 from the back side. Reference numeral 4 is an access tunnel to the storage tank, 5 is a plug for sealing the opening of the storage tank, and 6 is a manhole.

By the way, in order to construct such a lining-type storage tank, after excavating the cavity 1, the lining material is attached to the inside of the cavity 1 while being floated from the surface of the cavity, and the hermetic container 2 is assembled. It is considered that it is preferable to employ a construction method in which the back concrete 3 is cast and filled on the back surface side of 2.
In that case, the airtight container 2 itself functions as a formwork for placing and filling the backfill concrete 3, but the lining material forming the airtight container 2 is a thin steel plate having a thickness of about 6 mm to 20 mm. Therefore, it is usually assumed that the lining material itself cannot sufficiently withstand the placing load of the back concrete 3 and the lining material is deformed.

  Therefore, in the case of the construction method as described above, it is indispensable to take measures for preventing the deformation of the lining material when placing the back concrete 3, and therefore, when the airtight container 2 is assembled, the lining is provided on the back side. Appropriate reinforcing material or stiffener for reinforcing the material is incorporated, or temporary support for supporting the lining material inside the airtight container 2 when placing the back concrete 3 It is said that it is necessary to provide a work.

Further, Patent Document 1 and Patent Document 2 propose that the back-filled concrete 3 is placed by an underwater concrete placing method. This is because water is injected into the inside and outside of the airtight container 2 to store the stored water at a predetermined level, so that the concrete placement pressure acting on the outside of the lining material is countered by the water pressure acting on the inside of the lining material. It uses a treme tube in the water outside the wood to place the back concrete and replace it with water.
JP 2001-164589 A JP 2001-323490 A

However, as described above, incorporating a reinforcing material or stiffening material outside the lining material inevitably interferes with a large number of reinforcing bars that are complicatedly arranged in the backing concrete 3. In addition, it is difficult to provide a temporary support in the hermetic container 2, and sufficient curing of the lining material is indispensable, and the burden is great in terms of construction period and construction cost.
Furthermore, as proposed in Patent Document 1 and Patent Document 2, the construction of the back concrete 3 by the underwater concrete placement technique requires complicated process management and quality control for underwater concrete placement. It is not realistic because the work becomes complicated.

  In any case, in the case of using the construction method in which the airtight container 2 is assembled and then the backside concrete 3 is cast and filled on the back side, a narrow and closed space between the airtight container 2 and the cavity 1 is used. Therefore, it is necessary to pay sufficient attention so as to completely and solidly place good quality concrete in the entire filling space. Although it is necessary to reliably prevent air accumulation in the filling space, this is not always easy.

  In view of the above circumstances, the present invention is an effective and appropriate construction method for constructing this type of rock storage tank, and in particular, the back side concrete is efficiently applied to the back side without deforming the lining material forming the airtight container. An object of the present invention is to provide a construction method capable of being cast and filled.

  According to the first aspect of the present invention, an airtight container is formed by covering the inner surface of the cavity formed in the rock with a lining material, and a backfill concrete filling space is ensured between the airtight container and the cavity. And a method of constructing a storage tank in a rock mass by stepping and filling backfilled concrete into the filling space from the bottom toward the top, and to the bottom of the backfilled concrete filling space. After carrying out the first-stage concrete placing process, prior to the next-stage concrete placing process, the stored water is poured into an airtight container and the water level is maintained at a position higher than the next-stage concrete placing schedule top. In that state, the next-stage concrete placing process is carried out in the air, and thereafter, the water level rising process by further water injection into the airtight container and the filling space up to a position lower than the water level Concreting steps C. in air will repeatedly stepwise to, concreting step to the highest portion of the filling space and performing an airtight container as filled with water.

  The invention according to claim 2 is the construction method of the in-bed storage tank according to claim 1, wherein the grout material is added to the topmost part of the filling space prior to the concrete placing step on the topmost part of the filling space. An injection pipe for pressure injection and a return pipe for returning the grout material are arranged in advance, and the final-stage concrete placing step to the top of the filling space is performed to connect the injection pipe and the return pipe. After embedding in the back-filled concrete, a pressure injection step for further pressure injection of the grout material to the top of the filling space through the injection pipe is performed, and the pressure injection step is performed by the return pipe It is characterized by continuing until it is returned through.

  According to the present invention, water is poured into an airtight container when the lining concrete is placed in stages, and the water level is maintained at a position higher than the next concrete placing planned top end. Thus, the lining material can be effectively prevented from being deformed by the concrete placement pressure by placing and filling the backside concrete in the air while supporting the lining material from the inside by the water pressure. Therefore, according to the present invention, special reinforcement and temporary support for the lining material can be omitted, and it is only necessary to inject water into the airtight container to maintain the water level appropriately, and the progress of the construction. Since it is only necessary to raise the water level step by step, no troublesome labor and cost are required. Of course, the placement of the back-filled concrete in the filling space may be carried out by simply performing the step of placing the aerial concrete, so that it is troublesome as in the case of underwater concrete placement as shown in Patent Documents 1 and 2. Complicated construction management is unnecessary, and workability can be greatly improved as compared with it.

  Also, prior to placing the concrete on the topmost part, the grout material injection pipe and the return pipe are arranged in advance there, and after placing the back concrete on the topmost part, the grout material pressure injection process By carrying out the above, it is possible to completely block the air reservoir that may be generated at the top by the pressure injection of the grout material.

An embodiment of the present invention will be described with reference to the drawings. In the construction method of the present embodiment, when constructing the lining-type rock storage tank shown in FIG. 1, the cavity 1 is first excavated as described above, and the airtight container 2 made of the lining material is assembled therein, and then the airtight container 2 is made to function as a formwork, and the back concrete 3 is cast and filled on the back side.
In this embodiment, the concrete placing process into the filling space of the back-filled concrete 3 is performed step by step from the bottom as usual, but the lining material forming the hermetic container 2 is made of concrete. In order to prevent deformation due to installation pressure, the inside of the airtight container 2 is filled with water, and the lining material is supported from the inside by the water pressure. To do.

Hereinafter, a specific construction procedure will be described with reference to FIGS.
After excavating the cavity 1 and assembling the hermetic container 2 inside it and securing a filling space for the backing concrete 3 between them, as shown in FIG. Pipe to reach the bottom through. Then, concrete is pumped from the concrete transporting vehicle 8 arranged in the access tunnel 4 to the concrete placing pipe 7 by the concrete pumping vehicle 9 arranged at the position where the plug 5 is to be constructed. First, the first stage is placed at the bottom of the filling space. The bottommost back-filled concrete 3a is cast and formed. The placement height (first lift) at the first stage may be appropriately set in consideration of the scale of the storage tank and the like, but may be about 1 m, for example.

Next, prior to placing the second stage, water is poured into the airtight container 2 to store the stored water W as shown in FIG. While maintaining the high position, the second-stage concrete placing step is carried out while pulling up the concrete placing pipe 7 in this state to form the second-stage back concrete 3b. The placement height (second lift) at this time may be set as appropriate. For example, it is set to about 1 m, and in that case, the water level WL is set to a position higher by about 0.5 m, for example.
In addition, when the water level WL of the stored water W and the planned ceiling end of the concrete to be placed are higher than the opening of the airtight container 2, a mold is attached to the opening.
As a result, the concrete placement pressure acting on the back side of the lining material is supported from the inside by the water pressure of the stored water W in the hermetic container 2 so that a large placement pressure does not act on the lining material. There is no such thing as deformation. Moreover, since the placement of the back-filled concrete 3 on the outside of the airtight container 2 is performed by the concrete placement in the normal air, not in the water, the case of using the underwater concrete placement method as shown in Patent Documents 1 and 2 Does not require any troublesome construction work and complicated construction management.

  Hereinafter, similarly, as shown in FIGS. 4 to 6, the water level WL in the airtight container 2 is raised stepwise and the concrete placing pipe 7 is raised stepwise, and the opening is opened. The third stage, the fourth stage, and the fifth stage of the back-filled concrete 3c, 3d, and 3e are cast and formed step by step while appropriately raising the formwork to be attached to. In the case of the illustrated example, as shown in FIG. 6, the inside of the airtight container 2 is filled when the fifth stage back concrete 3e is placed, and after that, the placing is continued with the water filled. I am going to do it.

As shown in FIG. 6, after the placement up to the height at which the opening is almost closed is completed, the placement on the top of the airtight container 2 is performed separately on the back side and the near side. That is, as shown in FIG. 7, the wife mold 10 is attached so as to divide the top placement space forward and backward, and first, as shown in FIGS. 7 to 9, with respect to the back side of the wife mold 10. Concrete placement is performed in three stages to place and form back concrete 3f, 3g, and 3h.
However, as shown in FIG. 9, prior to placing the final stage on the top, an injection pipe 11 and a return pipe 12 for pressurizing and injecting the grout material into the top of the filling space are arranged in advance.

In this state, the back concrete 3h is cast and formed on the innermost side of the topmost portion of the filling space, and then the end form 10 is disassembled, and the injection pipe 11 and the return pipe 12 are connected to the opening as shown in FIG. Extend to the outside.
Thereafter, the final filling space left on the near side is placed in the final stage, and the back concrete 3i is cast and formed. At that time, the concrete is pumped while pulling out the concrete placing pipe 7 and is placed until the return of the concrete is confirmed from a pre-installed hose (not shown) at the top of the filling space, As a result, the back concrete 3i is almost completely filled without leaving an air pocket at the top.

Since the entire filling space is filled with the back concrete 3 as described above, the stored water W in the airtight container 2 is appropriately drained.
Subsequently, as shown in FIG. 11, a pressure injection step for further pressure injection of the grout material to the top through the injection tube 11 is performed so that a slight air pocket is not left at the top. . That is, a grout material such as mortar with high fluidity is pumped from the grout pump mixer wheel 14 to the top through the injection pipe 11 and the operation is continued until the pumped grout material is returned from the return pipe 12. As a result, even if a slight air pocket or unfilled portion remains at the top of the filling space, the grout material can be filled to every corner, and the entire filling space can be completely and sufficiently densely backed. Embedded concrete 3 can be cast and formed. The injection tube 11 and the return tube 12 may be buried as they are.

As explained above, according to the construction method of the present embodiment, water is poured into the airtight container 2 when the backing concrete 3 is placed in stages, and the stored water W is stored. By maintaining the water level WL at a position higher than the next top of the concrete placement planned top, the lining material can be supported from the inside by the water pressure, and deformation of the lining material due to the concrete placement pressure can be effectively prevented. it can. For that purpose, it is only necessary to inject water only into the hermetic container 2 to maintain the water level WL appropriately, and as the construction progresses, the water level WL is simply raised stepwise to the desired water level. Since it can be filled with water, it does not require any extra time and effort.
Therefore, according to the present invention, it is possible to eliminate the need for special reinforcement or temporary support for the lining material. Since it should just be implemented by the method, troublesome and complicated labor and management as in the case of the underwater concrete placing method as shown in Patent Documents 1 and 2 are unnecessary, and the workability can be greatly improved.

  In addition, when the airtight container 2 is assembled in advance and the back-filled concrete 3 is filled into the narrow closed space on the back side, it is assumed that an air pocket is generated at the top and cannot be completely filled. Prior to placing the concrete on the top as in the embodiment, the injection pipe 11 and the return pipe 12 are arranged in advance, and after placing the back concrete 3h on the top, the grout material is further injected under pressure. Thus, even if an air pocket occurs at the top, it can be completely filled with a grout material. However, if there is no concern of air trapping, such as when an effective air vent can be provided at the top, the grout pressure injection step may be omitted.

  Although one embodiment of the present invention has been described above, the above embodiment is merely a preferred example, and the present invention is not limited to the above embodiment, and specific steps and detailed configurations of the present invention, For example, the number of concrete placement steps and the placement range of each step may be changed as appropriate within the scope of the present invention, depending on the shape, scale and other conditions of the storage tank to be constructed. Needless to say.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, and is a diagram showing an outline of a lining-type rock storage tank to be constructed by the method of this embodiment. It is a figure which shows the placement process of the first stage of back concrete. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the placement process of the next step. It is a figure which shows the press injection process of a grout material equally.

Explanation of symbols

1 Cavity 2 Airtight container (lining material)
3 (3a to 3i) lining concrete 4 access tunnel 5 plug 6 manhole 7 concrete placing pipe 8 concrete transport vehicle 9 concrete pump truck 10 wife formwork 11 injection pipe 12 return pipe 14 grout mixer pump truck W stored water WL water level

Claims (2)

The inner surface of the cavity formed in the bedrock is covered with a lining material to form an airtight container, and on the back side of the airtight container, a backfill concrete filling space is secured between the cavity and the bottom of the filling space It is a method of constructing a storage tank in a rock mass by stepping and filling backfilled concrete from the top to the top,
After the first-stage concrete placement process to the bottom of the backfill concrete filling space, the stored water is poured into the airtight container prior to the next-stage concrete placement process, and the water level is poured into the next-stage concrete placement process. Maintain it at a position higher than the top of the planned installation, and in that state, carry out the next concrete placement process in the air.
After that, the water level rise process of the stored water by further water injection into the airtight container and the concrete placement process in the air to the filling space up to a position lower than the water level are repeated step by step, A method for constructing a storage tank in a rock mass, wherein the concrete placing step is performed with the inside of an airtight container filled with water to the top of the filling space. A construction method of a rock storage tank according to claim 1,
Prior to the concrete placing step on the top of the filling space, an injection pipe for pressurizing and injecting the grout material to the top of the filling space and a return pipe for returning the grout material are arranged in advance.
After carrying out the final stage concrete placing process to the top of the filling space and burying the injection pipe and the return pipe in the back concrete,
Performing a pressure injection process for further pressure injection of the grout material to the top of the filling space through the injection pipe and continuing the pressure injection process until the grout material is returned through the return pipe; The construction method of the storage tank in the bedrock characterized by this.

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