JP2015081807A - Radioactive waste disposal tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radioactive waste disposal tunnel capable of preventing cracking and breakage of a timbering which covers the inner peripheral surface of a tunnel.SOLUTION: A radioactive waste disposal tunnel 1 forms a tunnel 11 by digging a natural ground 12, and includes an annular timbering 20 that covers the inner peripheral surface of the tunnel 11. In this radioactive waste disposal tunnel 1, the timbering 20 has a segment 22 installed on the bottom part of the tunnel 11 formed thicker than a segment 22 installed at the other region, and the provision of a crushed stone layer 30 filled with a crushed stone 31 between the timbering 20 except for the bottom part and the tunnel 11 allows even an artificial barrier integrated module heavy in weight to be stably disposed of.

Description

  The present invention relates to a radioactive waste disposal tunnel that disposes of radioactive waste discharged from, for example, a nuclear power plant.

  For example, a geological disposal facility for radioactive waste discharged from a nuclear power plant will aim to be as deep as possible from the original purpose of the facility, and it will be safe to embed and store waste by building it below 300m underground. I have to.

  In such disposal of radioactive waste, it is considered that leakage to groundwater is suppressed by covering the periphery of the waste with a viscous material such as bentonite. However, when a cement-based member is constructed in the vicinity of bentonite, the elution of cement components occurs in a period of a thousand or tens of years, leading to deterioration of the bentonite material, making it impossible to ensure the low-permeability performance of bentonite for an extremely long period. I understand that. In order to eliminate such a concern, a support member that uses as little cement material as possible is necessary.

  As a supporting structure that uses as little cement-based material as possible, the present applicant has proposed a rock utilization segment as disclosed in Patent Document 1. The rock use segment is a composite segment that combines a steel frame and a rock block such as granite. The steel frame is filled with a brick-like rock block, and the gap formed between the rock blocks is filled with mortar. Thus, the structure is designed to be integrated as a segment. In this segment, mortar is used only to fill gaps between rock blocks, so the amount used is less than that of shotcrete or concrete segments, which may greatly reduce the use of cement.

  Furthermore, the present applicant has proposed a method of constructing a mine shaft using a rock utilization segment in Patent Document 2. In this method, backfilling using crushed stone is performed as a backfilling material that uses as little cement-based material as possible for the gaps between the ground wall of the mine shaft and the segment associated with the assembling work of the rock use segment. . That is, after the construction of the mine is completed, an artificial barrier such as waste and cushioning material is buried, and then when the mine is backfilled, bentonite-based materials are injected into this crushed stone layer, Fill the gap and improve the low water permeability area so that there is no water channel as a radionuclide migration path.

JP 2002-250795 A JP 2009-276335 A

  By the way, there are a vertical placement method shown in FIG. 14 (A) and a horizontal placement method shown in FIG.

  In the vertical installation method shown in FIG. 14 (A), an artificial barrier 106 is formed in the disposal hole 104 drilled in the vertical direction from the bottom of the tunnel (disposal tunnel) 102 connected to the ground (ground facility) by the vertical shaft 100. Then, the vertical shaft 100 and the shaft 102 are backfilled with the backfill material 108. In FIG. 14A, reference numeral 110 denotes a water stop plug, and reference numeral 112 denotes a small crushing zone. In the case of this vertical placement method, when the tunnel 102 is backfilled, bentonite-based material or the like can be injected from the inner space side of the tunnel 102 into the crushed stone layer on the back surface of the support work 114 such as the rock utilization segment.

  On the other hand, in the horizontal installation method shown in FIG. 14B, after the artificial barrier 106 is placed in the tunnel 102, the shaft 100 and the tunnel 102 are backfilled with the backfill material 108. In FIG. 14B, reference numeral 116 indicates a dynamic plug. In the case of this horizontal placement method, an artificial barrier 106 such as a waste body and a cushioning material is fixed in the tunnel 102, so that a work space cannot be secured, and the crushed stone layer on the back surface of the support work 114 can be seen from the inner side of the tunnel 102. It is difficult to inject bentonite-based materials.

  14B, at present, a PEM (Prefabricated Engineered Barrier System Module) system, which is one of the choices for the placement method of the artificial barrier 106, is considered to be a promising target for future technological development. ing. The PEM system is a module that integrates waste, overpacks, and cushioning materials in a steel container at a ground facility (hereinafter referred to as an “artificial barrier integrated module”). It is a method of transporting and placing in underground facilities. As shown in FIG. 15, for example, the artificial barrier integrated module 118 is placed through a pedestal 122 inside a segment (a rock utilization segment) 120 serving as a support for the tunnel 102. In FIG. 15, reference numeral 124 indicates a crushed stone layer.

  However, the general artificial barrier integrated module 118 has, for example, a weight of about 30 tons, a pedestal width of about 0.7 m, a length of about 3.0 m per module, and 0.14 MPa. A distributed load acts on the segment 120. Since the elastic modulus of the crushed stone constituting the crushed stone layer 124 is considered to be smaller than the elastic modulus of the rocks on the wall surface of the segment 120 or the tunnel 102, when a distributed load is applied, the crushed stone layer 124 on the back surface of the segment 120 is deformed. Along with this, there is a concern that a local bending stress is generated in the segment 120, leading to the occurrence of cracks and destruction.

  The present invention has been made in consideration of the above-described problems of the prior art, and an object thereof is to provide a radioactive waste disposal tunnel capable of preventing cracking and destruction of a supporting work covering the inner peripheral surface of a mine shaft. And

  A radioactive waste disposal tunnel according to the present invention is a radioactive waste disposal tunnel provided with an annular support for excavating natural ground to form a tunnel and covering an inner peripheral surface of the tunnel. The construction is characterized in that a bottom portion of the mine shaft is formed thicker than other portions, and a crushed stone layer filled with crushed stone is provided between the support work except the bottom portion and the mine shaft.

  According to such a configuration, the bottom portion of the supporting work that covers the inner peripheral surface of the mine shaft is formed thicker than the other parts, and the crushed stone layer is not provided behind the supporting work at the bottom portion. When the artificial barrier integrated module having a large weight as a waste is placed, even if the distributed load due to its weight acts on the support, the rock on the wall surface of the tunnel directly supports the support at the bottom, Generation of local bending stress in the support work is avoided, and cracks and breakage of the support work can be prevented.

  Provided with a predetermined interval toward the excavation direction of the natural ground, a wife wall that closes the open end between the outer peripheral surface of the support work and the inner peripheral surface of the tunnel, A crushed stone filling port for filling the crushed stone in the closed space to form the crushed stone layer is formed, and each crushed stone filling port may be closed with a filling material after the crushed stone filling operation. If it does so, it can block | interrupt the groundwater which flows into a crushed stone layer from a natural mountain to the extension direction of a mine shaft by a wife wall.

  In this case, the bottom support is formed with a drainage hole for draining groundwater flowing into the crushed stone layer in the extension direction of the tunnel, and the drainage hole is refilled after the tunnel is filled, or It is good to close with the filling material at the same time as the backfilling work of the tunnel. As a result, during construction and operation of the mine shaft, groundwater whose flow in the direction of mine shaft extension is blocked by the gable wall flows to the lower part of the crushed stone layer, and then drains to the mine shaft through the drainage hole. The drainage structure is constructed so that a large water pressure does not act on the support work. Moreover, since the drainage hole is blocked by a filling material such as bentonite after the backfilling operation of the mine shaft or at the same time as the backfilling operation of the mine shaft, a high water shielding effect can be obtained.

  When bentonite is used as the filling material, high water shielding performance can be secured, and unlike a cement-based material, a water-permeable path is not generated by cracking.

  The support is constructed by arranging a plurality of segments formed by integrating rock blocks in a steel frame in the circumferential direction of the tunnel, and among the segments arranged in the circumferential direction, the bottom of the tunnel May be provided with a segment formed thicker than other portions.

  The radioactive waste placed in the internal space of the support work may be a module in which the radioactive waste is constructed in an integral manner by constructing an artificial barrier with a metal container and a cushioning material in a ground facility.

  According to the present invention, for example, when an artificial barrier integrated module having a large weight as a waste to be disposed is placed, even if a distributed load due to the weight acts on the support, the rock on the wall surface of the tunnel is at the bottom. Since the support work is directly supported, the occurrence of local bending stress in the support work is avoided, and cracking and breakage of the support work can be prevented.

FIG. 1 is a side sectional view showing a configuration of a radioactive waste disposal body constructed by applying a radioactive waste disposal tunnel according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a cross-sectional configuration along the line II-II in FIG. FIG. 3 is an explanatory view showing one step of the construction method of the radioactive waste disposal tunnel shown in FIG. FIG. 4 is an explanatory diagram illustrating a cross-sectional configuration along the line IV-IV in FIG. 3. FIG. 5 is a perspective view showing the configuration of the segments constituting the support work. FIG. 6 is an explanatory view showing one step of the construction method of the radioactive waste disposal tunnel shown in FIG. 1. FIG. 7 is an explanatory view showing one step of the construction method of the radioactive waste disposal tunnel shown in FIG. 1. FIG. 8 is an explanatory diagram showing a cross-sectional configuration along the line VIII-VIII in FIG. FIG. 9 is an explanatory diagram illustrating a state in which the wife wall illustrated in FIG. 8 is changed to an unfolded form. FIG. 10 is an explanatory view showing one step of the construction method of the radioactive waste disposal tunnel shown in FIG. FIG. 11 is an explanatory diagram showing a cross-sectional configuration along the line XI-XI in FIG. FIG. 12 is an explanatory diagram showing the flow of groundwater in the support work. FIG. 13 is a perspective view showing the configuration of the drain holes of the segments installed at the bottom of the support work. FIG. 14 is an explanatory view showing a method of placing a general radioactive waste in a tunnel, FIG. 14 (A) shows a vertical placement method, and FIG. 14 (B) shows a horizontal placement method. FIG. 15 is an explanatory view showing a state in which the artificial barrier integrated module is placed on the tunnel shown in FIG. 14 (B).

  Hereinafter, preferred embodiments of a radioactive waste disposal tunnel according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side sectional view showing a configuration of a radioactive waste disposal body 10 constructed by applying a radioactive waste disposal tunnel 1 according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II in FIG. It is sectional drawing which follows the -II line.

  A radioactive waste disposal tunnel 1 (hereinafter also simply referred to as “tunnel 1”) includes a tunnel (disposal tunnel) 11, an annular support 20 that covers the inner peripheral surface of the tunnel 11, a crushed stone layer 30, A wife wall 13 is provided. The radioactive waste disposal body 10 is installed in the internal space 20s of the support structure 20 with the artificial barrier integrated module 2 in which high-level radioactive waste (not shown) is modularized, and the internal space 20s is backfilled with the closing material 40 and closed. It is what.

  The artificial barrier integrated module 2 (hereinafter also simply referred to as “module 2”) is a unit in which waste 2a, overpack 2b, and cushioning material 2c are integrated in a steel container. For example, PEM (Prefabricated Engineered) (Barrier System Module) system. Within the mine shaft 11, the module 2 is placed on a support 20 at the bottom via a pedestal 26. For example, the module 2 has a weight of about 30 tons, a length of about 3.0 m, and a width of the base 26 of about 0.7 m. The form of the radioactive waste placed in the tunnel 1 is not limited, and may of course have a configuration other than the artificial barrier integrated module 2.

  The mine shaft 11 is formed by excavating the natural ground 12 with the excavator 50 shown in FIG. More specifically, the mine shaft 11 is formed by excavating the natural ground 12 with the excavator 50 in a predetermined excavation direction (left side in FIG. 3). The inner diameter of the mine shaft 11 is, for example, 5.4 m.

  The excavator 50 conveys the excavator main body 51 which is a free section excavator and the segments 22 and 22a for constructing the support work 20, and further assembles the segments 22 and 22a to construct the support work 20. 60.

  The excavator body 51 includes a cylindrical cutter head 52 that can rotate around an axis 51x of the excavation axis along the excavation direction, a cutter 53 that is attached to the outer peripheral surface of the tip of the cutter head 52, and the cutter head 52. Is provided with a drive source 54 for rotating the shaft around the axis 51x of the excavation shaft and four wheels 55. The excavator body 51 can be switched between a transmission state in which the driving force of the driving source 54 is transmitted to the wheels 55 and a non-transmission state in which the driving force of the driving source 54 is not transmitted to the wheels 55. When the vehicle is driven, the wheel 55 rotates and travels.

  The support assembly apparatus main body 60 includes a plurality of columns 61 erected at regular intervals in the internal space 20 s of the support 20 and beams 63 extending along the excavation direction and attached to the columns 61. ing.

  As shown in FIG. 4, the column 61 is formed in an arch shape that is bent at the center portion to form a U-shape in order to secure a region R <b> 1 in which the excavator body 51 moves along the excavation direction. A wheel 62 is provided at the lower end of the column 61, and the column 61 can move in the excavation direction and in the opposite direction when the wheel 62 travels on the rail 15. The distance between one end of the pillar 61 and the other end is, for example, 3.2 m.

  The beam 63 is attached to the central portion of the column 61. As shown in FIG. 3, the beam 63 is provided with first traveling means 63 a and second traveling means 63 b that travel in the excavation direction and the opposite direction with respect to the beam 63. In the present embodiment, the first traveling means 63 a is provided at the lower end portion of the beam 63, and the second traveling means 63 b is provided at the upper end portion of the beam 63.

  A support assembly means 70 for assembling the segments 22 and 22a to construct the support work 20 is attached to the first traveling means 63a. The support assembly means 70 includes a first shaft member 71 attached to the first traveling means 63a, and a second shaft attached to the first shaft member 71 in a state of being rotatable around the axis 70x of the rotation shaft. A member 72; a third shaft member 73 that is attached to the second shaft member 72 so as to be movable back and forth; and a holder (not shown) that is provided at the tip of the third shaft member 73 and holds the segments 22 and 22a. ing.

  As shown in FIG. 4, the second traveling means 63b includes a crushed stone discharging means 80 for discharging the crushed stone 31, and a bentonite discharging means 90 for discharging a viscosity material such as bentonite 32 (see FIG. 2) as a filling material. And are provided.

  The crushed stone discharging means 80 includes a crushed stone discharging means main body 81 attached to the second traveling means 63b, and a crushed stone discharging nozzle 82 for discharging the crushed stone 31 from the tip.

  The bentonite discharge means 90 includes a bentonite discharge means main body 91 attached to the second traveling means 63b, and a bentonite discharge nozzle 92 for discharging the bentonite 32 from the tip.

  The support (lining) 20 is a so-called lining, and is formed in an annular shape so as to cover the entire inner peripheral surface of the mine shaft 11 as shown in FIGS. 1 and 2. As shown in FIG. 3 and FIG. 4, the support work 20 is configured by arranging a plurality of cylindrical cylinders 21 along the excavation direction. The cylindrical body 21 is configured by arranging a plurality of arcuate segments 22 (22a) in the circumferential direction around the axis 51x of the excavation shaft, and is formed to have a width of 1 m in the excavation direction, for example. ing. The support work 20 has a thickness of a portion excluding the bottom portion of 0.1 m and an inner diameter of 5.0 m. A segment 22a having a thickness larger than that of the segment 22 installed at the other part is installed at the bottom of the support work 20, and the thickness of the segment 22a is, for example, 0.2 m, which is about twice that of the other part. Set to the thickness of

  As shown in FIG. 5, the segment 22 (22 a) is formed of a metal material such as steel, for example, and includes a segment main body 23 serving as an outer frame, a plurality of rocks 24 fitted into the segment main body 23, and the segment main body 23. And mortar (not shown) filled between the rock 24 and the rock 24. A low alkali cement is used for this mortar.

  The segment (bottom segment, bottom widened segment) 22a that constitutes the bottom of the support work 20 is configured so that the plate thickness is thicker than the segment 22 that constitutes another part (side and top of the support work 20). The overall structure may be the same as that of the segment 22. The crushed stone layer 30 is not provided behind the segment 22a, and the segment 22a is installed directly on the inner peripheral surface (the ground 12) of the mine shaft 11.

  4 and 13, the segment 22a includes a drain hole 25a extending along the excavation direction of the mine shaft 11 in a state of being installed on the inner peripheral surface of the mine shaft 11, and a curved surface direction of the segment 22a ( A drainage hole 25b that is provided along the arc direction and is orthogonal to the drainage hole 25a is formed. The drainage holes 25 a communicate with each other between the drainage holes 25 a of adjacent segments 22 a provided along the excavation direction of the mine shaft 11, and communicate with the extension direction of the mine shaft 11. As shown in FIG. 4, the drain hole 25b opens at a position corresponding to the crushed stone layer 30 on the side of the segment 22a, and allows groundwater that has passed through the crushed stone layer 30 to flow to the drain hole 25a.

  The rock 24 is formed so as to be fitted into the segment main body 23 by cutting, for example, sedimentary rock, metamorphic rock, or igneous rock. As the rock 24, it is preferable not to use a limestone such as a sedimentary rock as described above that contains antaritic components such as calcium and potassium. That is, the rock 24 in this embodiment does not contain an alkaline component.

  As shown in FIGS. 1 and 2, the crushed stone layer 30 is provided in a gap between the inner peripheral surface of the mine shaft 11 and the outer peripheral surface of the support work 20, and the support work 20 in which the segment 22a is disposed. It is not installed at the bottom. The crushed stone layer 30 is composed of crushed stones 31 such as pea gravel formed by crushing rocks not containing antaritic components such as calcium and potassium, and the crushed stone 31 is a comparison of 2.5 to 10.00 mm, for example. It consists of gravel with a small particle size.

  Note that even the crushed stone 31 containing an alkaline component can be used as long as the content of the alkaline component does not affect the barrier performance. Here, the barrier performance means “performance that is equivalent to the delay performance of the surrounding rock in the migration of nuclides in the backfill material and the buffer material”. Moreover, when the alkaline component of the crushed stone 31 is more than an allowable value, it can be used by applying a dealkalization treatment or the like to make it less than the allowable value.

  The end wall 13 forms a space for filling the gap between the inner peripheral surface of the mine shaft 11 and the outer peripheral surface of the cylindrical body 21 with the crushed stone 31 while preventing the crushed stone 31 from flowing out to the front end side of the mine shaft 11. A partition wall is provided at regular intervals along the excavation direction. As shown in FIGS. 8 and 9, the end wall 13 includes a filling nozzle 13 a, a through nozzle 13 b, and a bag body 13 c having a filling space inside.

  The filling nozzle 13a includes a filling port that communicates with the filling space inside the bag 13c. The through-nozzle 13b has a nozzle connection port and a crushed stone discharge used when filling a gap between the inner peripheral surface of the tunnel 11 and the outer peripheral surface of the cylindrical body 21 defined behind the end wall 13 with the crushed stone 31. And an exit. The nozzle connection port and the crushed stone discharge port are not in communication with the filling space of the bag 13c, and the nozzle connection port and the crushed stone discharge port are in communication with each other.

  As shown in FIG. 8, the bag 13c is in a folded storage form when the filling space is not filled with a filling material such as bentonite 32, while the filling material is filled in the filling space as shown in FIG. In the filled state, it switches to the expanded form.

  Here, the installation method of the wife wall 13 is demonstrated. Here, the description will be made on the assumption that the excavation space DS (see FIG. 3) formed by the excavating device 50 exists on the distal end side of the mine shaft 11 of the natural ground 12.

  First, as shown in FIG.7 and FIG.8, the bag body 13c made into the accommodation form is installed in the outer peripheral surface of the cylinder 21 newly installed in the front end side of the excavation direction. The bag 13c in the storage form is installed at a predetermined interval (1 m in the present embodiment) with respect to the rear end wall 13 filled with the bentonite 32 and in the developed form.

  Next, the bentonite discharge nozzle 92 is inserted into the filling port of the filling nozzle 13a of the end wall 13 in the storage form to discharge the bentonite 32, thereby filling the filling space of the bag 13c with the bentonite 32. Then, as shown in FIGS. 7 and 9, the bag body 13 c (the end wall 13) that has been inflated and changed to the expanded form by being filled with the bentonite 32 is filled with the outer periphery of the cylindrical body 21 from the excavation space DS as shown in FIGS. 7 and 9. The gap 16s between the surface and the inner peripheral surface of the mine shaft 11 is divided. In this state where the gap 16s is divided from the excavation space DS, the through nozzle 13b has a nozzle connection port disposed on the excavation space DS side and a crushed stone discharge port disposed on the gap 16s side. Therefore, if the crushed stone 31 is discharged by inserting the tip of the crushed stone discharge nozzle 82 into the nozzle connection port, the crushed stone 31 can be filled in the gap 16s (see FIGS. 10 and 11).

  As shown in FIGS. 1 and 2, the closing material 40 is a backfilling material for closing the internal space 20 s of the support work 20. When the rock mass which comprises the natural ground 12 does not contain an alkaline component, the obstruction | occlusion material 40 uses the rock which generate | occur | produces when excavating the natural ground 12 with the excavator 50, and crushes this rock. The bean gravel thus formed may be used, and the bean gravel and bentonite 32 may be mixed and formed. On the other hand, when the rock mass which comprises the natural ground 12 contains an alkaline component, the block material 40 uses the bean gravel formed by crushing the rock which does not contain an alkaline component, and this bean gravel and bentonite 32 are mixed. To form. The blocking material 40 is filled in the internal space 20 s of the support 20 after high-level radioactive waste is installed in the internal space 20 s of the support 20.

  Next, the construction method of the tunnel 1 and the radioactive waste disposal body 10 configured as described above will be described step by step, and the drainage / water shielding structure in the support work 20 constituting the tunnel 1 will be described. Here, as shown in FIG. 3, a plurality of cylinders 21 are connected along the excavation direction, and a pair of rails 15 for guiding the movement of the pillars 61 are provided in the lower part of the internal space 21 s of the cylinders 21. In the following description, it is assumed that the soil material 14 is provided so as to extend along the excavation direction, and further has a flat upper surface so that the excavator body 51 can travel.

  First, as shown in FIG. 3, in the excavator 50, the excavator body 51 is arranged on the front side in the excavation direction with respect to the support assembly apparatus body 60. Then, the driving source 54 is driven in a state where the driving force of the driving source 54 is switched to the non-transmitting state where the driving force is not transmitted to the wheels 55, and the cutter head 52 is rotated about the axis 51x of the excavating shaft, while the excavator body 51 is not The transmission state is switched to the transmission state, and the excavator body 51 is caused to travel in the excavation direction.

  When the cutter 53 comes into contact with the natural ground 12 in this state, the natural ground 12 is excavated by the cutter 53 in the excavation direction. Further, from this state, the cutter head 52 is moved in the up and down direction and the left and right direction to excavate the natural ground 12 by the cutter 53, and as shown in FIG. A communicating excavation space DS is formed, and the mine shaft 11 is extended in the excavation direction. Such excavation is performed until the width of the excavation space DS in the excavation direction becomes larger than the width of the cylindrical body 21 in the excavation direction. In the present embodiment, since the width of the cylindrical body 21 in the excavation direction is 1 m, the natural ground 12 is excavated until the width of the excavation space DS in the excavation direction becomes 1 m or more.

  Next, a new cylinder 21 is constructed by installing the segments 22 and 22a in the excavation space DS. When installing the segments 22 and 22a, as shown in FIG. 6, the excavator body 51 is moved in the direction opposite to the excavation direction, the support assembly apparatus body 60 is moved in the excavation direction, and the excavator body 51 is moved. And the support assembly apparatus main body 60 are replaced. Then, each segment 22, 22a is individually conveyed by running the first running means 63a, and the segment 22a is provided at the bottom of the mine shaft 11 by the support assembly means 70, and the segments 22 are provided in the circumferential direction on the side portions thereof. Thus, the cylindrical body 21 is constructed.

  Thereafter, as shown in FIGS. 7 and 8, after the bag 13c in the storage form is disposed on the distal end side of the outer peripheral surface of the cylindrical body 21 in the excavation direction, the distal end of the bentonite discharge nozzle 92 is inserted into the filling port of the filling nozzle 13a. Insert. Then, the bentonite 32 is discharged from the tip of the bentonite discharge nozzle 92, and the filling space of the bag 13c is filled with the bentonite 32 to switch to the unfolded form, thereby defining the end wall 13. By the end wall 13, the excavation space DS is formed. Then, the gap 16s between the outer peripheral surface of the cylinder 21 and the inner peripheral surface of the mine shaft 11 is divided.

  Subsequently, as shown in FIGS. 10 and 11, after inserting the tip of the crushed stone discharge nozzle 82 into the nozzle connection port of the through nozzle 13 b of the end wall 13, the crushed stone 31 is discharged from the tip of the crushed stone discharge nozzle 82, The crushed stone 31 is filled in the gap 16s.

  Next, the bentonite discharge nozzle 92 is inserted into the nozzle connection port of the through nozzle 13b of the end wall 13 to discharge an appropriate amount of bentonite 32, and the through nozzle 13b is blocked by the bentonite 32 (see FIG. 12).

  The work as described above, specifically, excavating the natural ground 12 to form the excavation space DS, installing a plurality of segments 22 and 22a in the excavation space DS to construct the cylindrical body 21, The end wall 13 is installed on the distal end side to divide the gap 16 s from the excavation space DS, and after filling the gap 16 s with the crushed stone 31, the penetrating nozzle 13 b is closed with the bentonite 32 and extends in the excavation direction. The mine shaft 11 is formed, and the cylindrical body 21 is extended in the excavation direction.

  Thus, in this embodiment, after the chamfer 31 is filled in the gap 16s separated from the excavation space DS by installing the end wall 13, the penetrating nozzle 13b which is a filling port (crushed stone filling port) of the crushed stone 31 is used as a filling material. It is blocked by bentonite 32. Thereby, when forming the mine shaft 11 extending in the excavation direction and constructing the cylindrical body 21 (supporting work 20) extending in the excavation direction, each of the end walls 13 is provided with a water barrier, and the crushed stone from the wall surface of the mine shaft 11. Groundwater entering the layer 30 does not flow into the crushed stone layer 30 before and after the wife wall 13 is sandwiched.

  For this reason, the groundwater infiltrated into the crushed stone layer 30 between the adjacent walls 13 and 13 with water-blocking properties loses the flow field in the extending direction of the mine shaft 11, and as shown by the arrows in FIG. The gap in the layer 30 flows downward along the outer peripheral surface of the cylindrical body 21 formed by the segment 22, and is blocked by the side surface of the bottom segment 22a so as to be filled with groundwater from the lower portion toward the upper portion. At this time, since the drainage holes 25a and 25b communicating from the side surface to the front and rear end faces are formed in the bottom segment 22a, the groundwater flowing into the crushed stone layer 30 to fill the drainage holes 25a and 25b The water is drained through 25 b and drained to the wellhead of the tunnel 11 through the drainage holes 25 a communicating between the segments 22 a arranged in the extending direction of the tunnel 11. That is, at the time of construction and operation of the mine shaft 11, since groundwater is discharged to the outside of the mine through the drainage path that continues to the pit of the mine shaft 11 formed by the drain holes 25 a and 25 b, a large water pressure does not act on the support work 20. A drainage structure is constructed.

  As described above, the support body 20 having a length set in advance in the excavation direction is constructed by connecting the cylinders 21, and then the soil material 14 and the rail 15 are removed, and the internal space 20 s of the support work 20 is removed. Module 2 is installed in (see FIG. 1). Thereafter, the inner space 20 s of the support work 20 is backfilled with the closing material 40 in the closing direction opposite to the excavation direction, and the mine shaft 11 is closed.

  At the end of the backfilling operation when the mine shaft 11 is closed, or at the same time as the backfilling operation, the drain holes 25a and 25b of the bottom segment 22a of the support work 20 are sequentially adjusted from the back side of the mine shaft 11 to the viscosity of the bentonite 32 and the like. A system material (filling material) is injected to completely occlude (see FIG. 2). Thereby, the water-impervious structure after the mine shaft 11 is closed is also constructed.

  As described above, the radioactive waste disposal tunnel 1 according to the present embodiment is formed by excavating the natural ground 12 to form the mine shaft 11 and providing the annular support 20 that covers the inner peripheral surface of the mine shaft 11. And the support work 20 is provided with the crushed stone layer 30 filled with the crushed stone 31 between the support work 20 except the bottom part and the mine road 11 except for the bottom.

  Thus, in the tunnel 1, the bottom part of the support work 20 is formed thicker than the other part, and the crushed stone layer 30 is not provided behind the support work 20 (segment 22a) at the bottom part. For this reason, even if a distributed load due to the weight of the module 2 acts on the support 20, the rock on the wall surface of the tunnel 11 directly supports the support 20 at the bottom, so that local bending stress is applied to the support 20. Generation | occurrence | production is avoided and the crack and destruction of the support work 20 can be prevented.

  In the tunnel 1, the end walls 13 that close the open ends between the outer peripheral surface of the support work 20 and the inner peripheral surface of the mine shaft 11 are provided at predetermined intervals in the excavation direction of the natural ground 12. Includes a through nozzle 13b having a crushed stone filling port for filling the crushed stone 31 into the space (gap 16s) closed by the wife wall 13 to form a crushed stone layer 30, and each through nozzle 13b is crushed. After the 31 filling operation, it is blocked by a filling material, for example, bentonite 32. Thereby, it is possible to block the groundwater flowing from the natural ground 12 into the crushed stone layer 30 in the extending direction of the mine shaft 11 by the wife wall 13.

  In this case, in the tunnel 1, drainage holes 25 a and 25 b for draining the groundwater flowing into the crushed stone layer 30 in the extending direction of the tunnel 11 are formed in the support 20 (segment 22 a) at the bottom. 25a and 25b are closed by a filling material such as bentonite 32 after the backfilling operation of the tunnel 11 or at the same time as the backfilling operation of the tunnel 11. Since the drainage holes 25a and 25b are provided in the bottom support 20 in this way, the groundwater in which the flow in the extension direction of the tunnel 11 is blocked by the end wall 13 during the construction and operation of the tunnel 11 is in the crushed stone layer 30. Then, the drainage hole 25a drains to the wellhead of the mine shaft 11, so that a drainage structure in which a large water pressure does not act on the support 20 is constructed. Moreover, since the drain holes 25a and 25b are closed by the filling material such as bentonite 32 after the backfilling operation of the mine shaft 11 or at the same time as the backfilling operation of the mine shaft 11, the vertical holes shown in FIG. It is possible to obtain a water shielding effect similar to that obtained when a viscous material such as bentonite is injected into the crushed stone layer on the back surface of the support work 114 from the inner side of the tunnel 102 to form a water shielding structure. That is, in the tunnel 1, a high water shielding structure can be constructed without injecting a viscosity material such as bentonite into the crushed stone layer 30.

By the way, bentonite 32 is a material that has existed stably in the natural underground environment for hundreds of thousands of years, and if there is no material that produces a chemical impact such as cement nearby, long-term soundness Can be expected. In the present embodiment, cement is used for the mortar that fills the gap between the rocks 24 of the segments 22 and 22a. However, since low alkali cement is used, the influence of the cement on the bentonite 32 and the like can be suppressed. In addition, since the amount of cement used can be greatly reduced as compared with the support work such as ordinary shotcrete, a reduction in uncertainty with respect to the influence of cement can be expected. Bentonite 32 is a material that fills the space by swelling and can expect a very small value of ^1-8 m / s to ^1-13 m / s. For example, bentonite 32 does not become a groundwater channel. Furthermore, unlike the cementitious material, the bentonite 32 does not have to worry about the generation of a water-permeable path due to cracking.

  In addition, when adopting a normal drainage system, it is necessary to cover the outer peripheral surface of the support with a waterproof sheet and install a drain pipe at the bottom.If organic matter such as a waterproof sheet or drain pipe is left behind, After the facility is closed, it is necessary to confirm that it will not significantly affect the nuclide migration delay performance. On the other hand, in the tunnel 1 according to the present embodiment, by providing the drain holes 25a and 25b in the bottom segment 22a, it is not necessary to install drain pipes, and the influence of leftovers can be reduced.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be freely changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Radioactive waste disposal tunnel 2,118 Artificial barrier integrated module 10 Radioactive waste disposal body 11,102 Tunnel 12 Ground mountain 13 Wife wall 13a Filling nozzle 13b Through-nozzle 13c Bag body 16s Cavity 20,114 Supporting work 21 Cylindrical body 22, 22a, 120 Segment 25a, 25b Drain hole 30,124 Crushed stone layer 31 Crushed stone 32 Bentonite 40 Blocking material 50 Excavator 51 Excavator body 60 Supporting assembly apparatus body 63a First traveling means 63b Second traveling means 70 Support assembly Means 80 Crushed stone discharge means 90 Bentonite discharge means

Claims (6)

A radioactive waste disposal tunnel provided with an annular support that covers an inner peripheral surface of the tunnel by excavating natural ground to form a tunnel.
The supporting work is formed such that the bottom of the mine shaft is thicker than other parts,
A radioactive waste disposal tunnel, characterized in that a crushed stone layer filled with crushed stone is provided between the supporting works excluding the bottom and the mine shaft. In the radioactive waste disposal tunnel according to claim 1,
Provided with a predetermined interval toward the excavation direction of the natural ground, the end wall closing the open end between the outer peripheral surface of the support work and the inner peripheral surface of the mine shaft,
Each wife wall is formed with a crushed stone filling port for filling the crushed stone in the space closed by the wife wall to form the crushed stone layer, and each crushed stone filling port is filled with crushed stone after filling operation Tunnel for radioactive waste disposal, characterized by being blocked by. In the radioactive waste disposal tunnel according to claim 2,
The bottom support is formed with a drainage hole for draining the groundwater flowing into the crushed stone layer in the extension direction of the mine shaft, and the drainage hole is refilled after the mine shaft is filled or after the mine shaft is buried. A radioactive waste disposal tunnel characterized by being blocked by a filler material at the same time as the return operation. In the radioactive waste disposal tunnel according to claim 2 or 3,
A radioactive waste disposal tunnel using bentonite as the filling material. In the radioactive waste disposal tunnel according to claim 1,
The support is constructed by arranging a plurality of segments formed by integrating rock blocks into a steel frame in the circumferential direction of the tunnel,
A radioactive waste disposal tunnel in which a plurality of segments arranged in the circumferential direction are arranged thicker than other portions at the bottom of the tunnel. In the radioactive waste disposal tunnel according to any one of claims 1 to 5,
The radioactive waste placed in the internal space of the support structure is an integral modularized construction of an artificial barrier with a metallic container and a cushioning material in a ground facility. Tunnel for radioactive waste disposal.

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