JP4958036B2 - Tunnel support structure - Google Patents

Description

  The present invention relates to a shaft support structure, and more particularly to a support structure suitable for use in a shaft for burying waste such as radioactive waste.

  For example, it has been studied to bury high-level radioactive waste in a deep underground area exceeding 300 m underground. At this time, the radioactive waste is solidified by mixing with glass, for example, and is disposed in a state in which the solidified glass is sealed with an overpack made of carbon steel or the like to form a waste. Then, as shown in FIG. 5, the waste body is connected to the main tunnel 1 connected in a substantially ring shape and in the relatively stable natural ground G of hard rock and sedimentary soft rock in the deep underground, and to the main tunnel 1. A waste burial disposal facility A composed of the formed disposal mine (tunnel) and disposal hole (hereinafter referred to as disposal mine 2) is constructed and disposed in the disposal mine 2 of this waste burial disposal facility A (for example, patent Reference 1). Also, in the disposal mine shaft 2 for disposing of the waste body, for example, when formed in the hard rock ground G, as shown in FIG. The rock bolt 3c formed by 3a and invert concrete (roadbed concrete) 3b etc. and fixed using cementitious material is installed in the natural ground G to prevent the natural ground G from collapsing into the disposal tunnel 2. Formed as follows.

  In addition, if the disposal mine 2 where the waste has been disposed is left as it is, the disposal mine 2 itself may form an excellent water path for groundwater, which may reduce the barrier performance of the disposal facility A as a whole. . For this reason, as shown in FIG. 7, the disposal tunnel 2 is made of a low-permeability material (buffer material) 5 equal to or higher than the natural ground G so as to wrap the waste body 4 in which the vitrified body 4a is sealed with the overpack 4b. It is considered to refill (close the disposal tunnel 2). And this kind of buffer material 5 is made of bentonite or bentonite mixed material which is excellent in swelling property and adsorptivity of radioactive substances, and the ground water infiltrated into the disposal tunnel 2 from the natural ground G comes into contact with it and swells. By pressing G, further infiltration of groundwater is prevented, or the permeation coefficient of the buffer material 5 decreases with swelling, thereby preventing infiltration of groundwater. This makes it possible to reliably dispose of high-level radioactive waste from the outside natural environment.

  However, as described above, when a cement-based material such as spray concrete or invert concrete is used for the supporting structure 3 of the tunnel 2 of the waste burying disposal facility A, when the ground water comes into contact with the Ca ( Calcium) and high alkali components are eluted, and there is a possibility that the periphery of the disposal tunnel 2 becomes a high alkali environment. And there exists a possibility that the disposal mine 2 may deteriorate by a highly alkaline environment, and the buffer material 5 may deteriorate by Ca ion. That is, Na (sodium) -type bentonite is frequently used for the buffer material 5 in that it has excellent swellability. When this Na-type bentonite comes into contact with Ca ions, Na and Ca are ion-exchanged, so that the swellability is improved. It changes to inferior Ca type bentonite. For this reason, the swelling property of the buffer material 5 becomes poor, and there is a possibility that the shielding ability of groundwater and consequently the shielding ability of radioactive substances (toxic substances) may be reduced.

  In addition, when shot concrete or inverted concrete is used for the support structure 3, the water impermeability of the support structure 3 itself is decreased due to aging deterioration (water permeability is increased), and there is a possibility that a leakage path T of harmful substances may be formed. is there. Furthermore, with the passage of time, a gap may be formed between the support structure 3 and the excavation surface G1 of the natural ground G, and this gap may become a leakage path T for harmful substances. In addition, when harmful substances leaked through the leakage route T are diffused to the ground surface through the natural ground G, especially when there is a highly permeable layer such as a crush zone that crosses the disposal facility A in the natural ground G. There is a risk of reaching the ground surface early and causing a serious accident.

On the other hand, there is a shaft support structure as disclosed in Patent Document 2, for example. This tunnel support structure has one steel support that is connected to another steel support (steel support member) at the front and back with a connecting material, and the center part is joined to the outer curved surface of this steel support. It is composed of a strip that supports a natural ground before and after the steel support, and a bean gravel filler that fills a gap (gap) between the strip and the natural ground. This tunnel support structure is a structure that supports the natural ground without using cement-based materials, so when applied to the disposal tunnel of a waste burial disposal facility, elution of Ca and high alkali components from the above cement There is no risk of causing deterioration of the cushioning material due to the above.
JP 2002-250795 A JP-A-11-44190

  However, in the shaft support structure as disclosed in Patent Document 2 described above, ground gravel is easy in the gap between the steel support and the strip and the natural ground because the gravel is used as the filler. Will penetrate. For this reason, when it applies to the disposal tunnel of a waste burial disposal facility, this gap part will become a leakage route of a hazardous substance.

  In view of the above circumstances, an object of the present invention is to provide a structure for supporting a mine suitable for use in a mine for disposing of waste such as radioactive waste.

  In order to achieve the above object, the present invention provides the following means.

The shaft support structure of the present invention is a shaft support structure that supports the natural ground provided along the excavation surface of the natural ground of the shaft for burying and disposing of waste, and is spaced in the axial direction of the tunnel And a plurality of steel support members arranged side by side with a clearance between the excavation surface, and an interposed member interposed so as to connect the steel support member and the excavation surface to the clearance. The steel sheet pile provided between the steel support members adjacent to each other with a gap between the excavation surface, and the gap between the steel support member and the steel sheet pile and the excavation surface is filled. A bentonite-based material filler , an abdominal erection linked to the adjacent steel support member, a steel pipe formed so as to be expandable, and a clay-based material filled in a hollow portion of the steel pipe, Friction fixing type lock that is supported at one end by the erection and extends into the natural ground. Characterized in that it comprises a belt.

In this invention, since the bentonite material is filled in the gap between the steel support member and the steel sheet pile and the excavation surface of the natural ground, the bentonite material swells as well as the ground water comes into contact with the steel support member and the steel. It is possible to increase the water-imperviousness of the gap between the sheet pile and the excavation surface of the natural ground, and it is possible to reliably block the groundwater from entering the tunnel from the natural ground. Moreover, even when the steel support member and the steel sheet pile are provided away from the excavation surface of the natural ground in this way, the natural ground can be supported by the steel support member via the interposed member. Moreover, since no cementitious material is used, it is possible to prevent the vicinity of the tunnel from becoming a highly alkaline environment.

Also, when filled with base bentonite-based material in the gap of the excavation surface of the steel支保member and the steel sheet piles and natural ground, via the wale and lock bolt swelling pressure generated when the ground water swells in contact It becomes possible to support in the natural ground. As a result, even when water impermeability is ensured with a filler, it is possible to reliably prevent deformation of the steel support member due to swelling pressure, and to provide a support structure that reliably and stably supports the natural ground. Can do.

Further, since the lock bolt is a friction fixing type lock bolt having a steel pipe formed so as to be expandable and a clay-based material filled in the hollow portion of the steel pipe, the steel pipe is attached to the drilled hole in the natural ground. After erection and expansion of the steel pipe and friction fixation on the natural ground, the natural ground can be reliably supported without using cement-based material by grouting the clay-based material in the hollow portion. This can reliably prevent the surroundings from becoming an alkaline environment.

  According to the mine shaft support structure of the present invention, it is possible to reliably support a natural ground, to prevent intrusion of groundwater from the natural ground, and to prevent the surroundings from becoming a highly alkaline environment. As a result, when applied to a tunnel in a waste disposal facility, the buffer material can be prevented from being deteriorated, and the steel support member, the steel sheet pile, and the excavation surface of the natural ground can be prevented by the clay-based material filler. It is possible to prevent the gap portion from becoming a leakage path for harmful substances, and it is possible to reliably bury waste in a stable state over a long period of time.

  Hereinafter, a mine shaft support structure according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. The present embodiment relates to a support structure for a disposal tunnel (tunnel) 2 provided in a waste burial disposal facility A for burying a high-level radioactive waste shown in FIG.

  As shown in FIGS. 1 to 3, the shaft support structure 10 of this embodiment is formed in an inverted U shape along the excavation surface G <b> 1 of the natural ground G, and is spaced in the direction of the axis O <b> 1 of the shaft 2. In addition, a plurality of steel support members 11 arranged side by side with a gap H between the excavation surface G1 and the steel support member 11 and the excavation surface G1 (natural ground G) are interposed in the gap H. A steel sheet pile 13 provided between adjacent steel support members 11 with a gap H between a wedge member (intervening member) 12 and the excavation surface G1, a steel support member 11 and a steel sheet pile 13 and a filler 14 of a clay-based material filled in a gap H between the excavation surface G1.

  The steel support member 11 is an H-shaped steel formed in an inverted U shape, and is provided along the side wall portion of the tunnel 2 and the excavation surface G1 of the arch portion. As shown in FIG. 2, the steel support members 11 adjacent to each other in the direction of the axis O1 of the mine shaft 2 are connected by a connecting member 15 such as a tie rod. Moreover, as shown in FIG. 1, each steel support member 11 is connected to one end of each of the plurality of wedge members 12 on a flange surface facing the excavation surface G1 side. Furthermore, the plurality of wedge members 12 connected to each steel support member 11 are provided at predetermined intervals in the extending direction of the steel support member 11, that is, in the circumferential direction of the mine shaft 2, and the other end of the ground mountain G is provided. It is made to contact with excavation surface G1. Thereby, the force from the natural ground G is transmitted to and supported by each steel support member 11 via the wedge member 12.

  Further, as shown in FIG. 2, the steel sheet pile 13 is formed in a corrugated cross-sectional shape, and the flange portion inside the tunnel 2 of the steel support member 11 adjacent to both ends in the direction of the axis O <b> 1 of the tunnel 2. Are provided to support each. At this time, as shown in FIGS. 1 and 3, the steel sheet pile 13 is provided along the side wall portion and the arch portion of the mine shaft 2 so as to fill the space between the adjacent steel support members 11.

  The clay-based material of the filler 14 of the present embodiment is a bentonite-based material, for example, bentonite powder, granular bentonite, or bentonite powder and / or a mixture of granular bentonite and sand.

  Further, as shown in FIGS. 1 and 3, the shaft support structure 10 of the present embodiment is provided with an abdomen 16 and a lock bolt 17. The flank 16 extends in the direction of the axis O <b> 1 of the mine shaft 2, is connected to the flange portion inside the mine shaft 2 of the adjacent steel support member 11, and is connected to the adjacent steel support member 11. The lock bolt 17 is extended in the natural ground G with one end connected to the fixing plate 18 supported by the flank 16. A plurality of such erections 16 and lock bolts 17 are provided at predetermined intervals in the circumferential direction of the mine shaft 2.

  Here, the lock bolt 17 of the present embodiment is a friction fixing type lock bolt, and as shown in FIGS. 4A and 4B, the outer surface 19a is provided with a concave portion 19b that is recessed inward so that it can expand. And a substantially cylindrical steel pipe 19 and a clay-based material 20 such as bentonite-based material filled in the hollow portion 19c of the steel pipe 19. As shown in FIG. 4 (a), the lock bolt 17 of the present embodiment configured as described above has a high-pressure water in the hollow portion 19c after the steel pipe 19 is built in the drilling hole 21 formed in the natural ground G. And the steel pipe 19 is expanded so as to expand its diameter, and the outer surface 19a is brought into close contact with the inner surface 21a. As a result, the lock bolt (steel pipe 19) 17 is fixed to the ground G by friction. Moreover, as shown in FIG.4 (b), the slurry of bentonite-type material (clay-type material 20) is grouted to the hollow part 19c, and the clay-type material 20 is filled into the hollow part 19c.

  Next, a method for installing the mine shaft support structure 10 having the above-described configuration will be described, and the operation and effect of the mine shaft support structure 10 of this embodiment will be described.

  The above-mentioned mine shaft support structure 10 excavates the mine shaft 2 by mechanical excavation and / or blasting excavation, and installs a steel support member 11 along the excavation surface G1 of the side wall portion and the arch portion of the mine shaft. A wedge member 12 is installed in a gap H between the support member 11 and the excavation surface G1. Thereby, the force from the natural ground G transmitted through the wedge member 12 is supported by the steel support member 11. In addition, the steel support members 11 adjacent to each other in the direction of the axis O <b> 1 are connected by the connecting member 15.

  Then, at the stage where the drilling hole 21 for installing the lock bolt 17 is drilled from the inner side of the tunnel 2 toward the natural ground G, as shown in FIG. 2, between the adjacent steel support members 11, the invert portion side The steel sheet pile 13 is sequentially installed, and the gap H between the excavation surface G formed by the steel sheet pile 13 and the gap H between the steel support member 11 and the excavation surface G1 are filled with the filler 14 of the bentonite material. I will do it. Then, at the stage where the steel sheet pile 13 and the filler 14 are filled, the upset 16 is installed so as to connect the adjacent steel support members 11. Further, the steel pipe 19 is built in the hole 21 and the lock bolt 17 is installed. Finally, the roadbed concrete (invert concrete) 22 shown in FIG. Thereby, the shaft support structure 10 of this embodiment is constructed | assembled.

  From the stage where the construction of the shaft support structure 10 is completed as described above, radioactive waste is carried into the shaft 2 and disposal is started. At this time, even when a force is applied from the natural ground G, since the force is supported by the steel support member 11 via the wedge member 12, the natural ground G is reliably supported in a stable state. In addition, even when groundwater tries to enter the mine shaft 2 from the natural ground G, the groundwater springed out from the natural ground G comes into contact with the filler 14 of the supporting structure 10 of the mine shaft, and the bentonite swells, and the hydraulic conductivity is increased. Intrusion of groundwater is prevented by lowering. On the other hand, the swelling pressure generated by the swelling of the bentonite is transmitted to the steel support member 11 through the steel sheet pile 13, and when the swelling pressure is large, the steel support member 11 is placed inside the tunnel 2. There is a possibility of deformation. However, in this embodiment, since the swelling pressure acting on the steel support member 11 is raised and supported by the natural ground G through the 16 and the lock bolt 17, the steel support member 11 is deformed. There is nothing. As a result, the radioactive waste is disposed in a suitable state in which the ground support G is supported in a stable state by the shaft support structure 10 of the present embodiment and the groundwater is prevented from entering the shaft 2.

  Then, at the stage where the radioactive waste is placed and disposed at a predetermined position, as shown in FIG. 7, the tunnel 2 is backfilled using the bentonite-based cushioning material 5. At this time, backfilling is performed while removing the roadbed concrete 22 in the invert portion. Thereby, since the cement-based material is not used for the mine shaft support structure 10 of the present embodiment in the mine shaft 2 after closing, the cement-based material is not completely left by removing the roadbed concrete 22. There is no risk of making the periphery of the mine shaft 2 into a highly alkaline environment. In addition, since no cementitious material is left in this way, there is no risk of the buffer material 5 deteriorating due to calcium ions or high alkali components as in the prior art, and radioactive waste is buried in a reliably stable state. It becomes possible to do.

  Further, even when groundwater tries to enter from the natural ground G after the tunnel 2 is closed, the filler 14 of the bentonite material is filled in the gap H between the steel support member 11 and the steel sheet pile 13 and the excavation surface G1. In other words, since the cushioning material 5 that wraps the radioactive waste is further covered with the filler 14, the filler 14 comes into contact with the groundwater and swells to ensure water shielding. In addition, even when a harmful substance leaks from the radioactive waste, the filler 14 swells and the ability to delay the migration to the harmful substance is ensured, so that there is no possibility that this part becomes a leakage path for the harmful substance. On the other hand, the steel support member 11 and the steel sheet pile 13 left interposed between the buffer material 5 and the filler 14 are subject to corrosion deterioration, and this part may become a leakage path for harmful substances. Since the gap caused by the corrosion of the steel support member 11 and the steel sheet pile 13 is filled by the swelling of the filler 14, it does not become a leakage path for harmful substances.

  Further, in the lock bolt 17 of the present embodiment, the steel pipe 19 may be corroded and become a leakage path of harmful substances, but the hollow portion 19c of the steel pipe 19 is filled with the clay-based material 20, particularly the bentonite-based material. Therefore, the gap caused by the corrosion of the steel pipe 19 is filled with the swelling of bentonite, and does not become a leakage path for harmful substances.

  Moreover, even when the roadbed concrete 22 is provided in the invert portion as in the present embodiment, the roadbed concrete 22 is removed when the buffer material 5 is backfilled, and therefore the invert portion may become a leakage path for harmful substances. Absent.

  Therefore, according to the shaft support structure 10 of the present embodiment, the excavation surface of the steel support member 11 and the steel sheet pile 13 and the natural ground G is filled with the bentonite material (clay material, filler 14). The water-imperviousness of H can be increased during G1, and groundwater can be reliably shut off. Further, even when the steel support member 11 and the steel sheet pile 13 are provided away from the excavation surface G1, the ground support G is supported by the steel support member 11 via the wedge member (interposition member) 12. be able to. And since the cement-type material is not used for the support structure 10, it can prevent that the periphery of the mine shaft 2 becomes a highly alkaline environment.

  Further, the swelling pressure of the filler 14 generated when the groundwater comes into contact and swells can be raised and supported by the natural ground G via the lock bolt 17. Thereby, even when water-imperviousness is ensured by the filler 14, it is possible to reliably prevent the steel support member 11 from being deformed by the swelling pressure, and to make the support structure 10 that reliably and stably supports the natural ground G. be able to.

  Furthermore, since the lock bolt 17 is a friction fixing type, that is, no cementitious material is used for fixing the lock bolt 17, it is possible to reliably prevent the periphery from becoming a highly alkaline environment.

  Therefore, according to the shaft support structure 10 of this embodiment, when applied to the shaft 2 of the waste burial disposal facility A, the buffer material 5 can be prevented from being deteriorated, and the support material 14 made of steel is supported by the filler 14. The gap H between the member 11 and the steel sheet pile 13 and the excavation surface G1 of the natural ground G can be prevented from becoming a leakage path for harmful substances, and the waste can be reliably buried in a stable state over a long period of time. Become.

As mentioned above, although one embodiment of the shaft support structure according to the present invention has been described, the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the scope of the present invention .

It is sectional drawing which shows the supporting structure of the mine shaft which concerns on one Embodiment of this invention. It is a perspective view which shows the supporting structure of the mine shaft which concerns on one Embodiment of this invention. FIG. 2 is a view taken along line XX in FIG. 1. It is sectional drawing of the rock volt | bolt with which the supporting structure of the mine shaft which concerns on one Embodiment of this invention comprises. It is a figure which shows a waste burial disposal facility. It is sectional drawing which shows the support structure of the disposal mine shaft of the conventional waste burial disposal facility. It is sectional drawing which follows the mine shaft direction which shows the state which disposed the radioactive waste in the disposal mine of the conventional waste burying disposal facility.

Explanation of symbols

1 Main tunnel 2 Disposal tunnel (tunnel)
3 Conventional shaft support structure 3a Shotcrete 3b Subbase concrete (invert concrete)
3c Rock bolt 4 using cement-based fixing material 4 Waste 5 Buffer material 10 Tunnel support structure 11 Steel support member 12 Wedge member (interposition member)
13 Steel sheet pile 14 Filler (clay material, bentonite material)
15 Connecting member 16 Raising 17 Lock bolt 18 Fixing plate 19 Steel pipe 20 Clay-based material 21 Drilling hole 21a Hole surface 22 Subbase concrete (invert concrete)
A Waste disposal and disposal facility G Ground mountain G1 Excavation surface H Clearance O1 Axis of tunnel T Leakage path of harmful substances

Claims (1)

A support structure for a mine shaft that is provided along the excavation surface of a mine shaft for burying and disposing of waste ,
A plurality of steel support members arranged side by side in the axial direction of the mine shaft and with a gap between the excavation surface, and the steel support member and the excavation surface are connected to the clearance. A steel sheet pile provided between the steel support members adjacent to each other with a gap between the mounted intervention member and the excavation surface, the steel support member, the steel sheet pile, and the excavation A bentonite-based material filler filled in the gap with the surface, an uprising connected to the adjacent steel support member, a steel pipe formed to be expandable, and a clay filled in the hollow portion of the steel pipe A mine shaft support structure , comprising: a system material, and a friction fixing type lock bolt that is supported on one end side of the flank and extends into the ground .

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