JP2010001633A - Tunnel, tunnel construction method, and device for suppressing cracking of lining concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of restraining lining concrete from being cracked due to the displacement of natural ground, in tunnel lining. <P>SOLUTION: This tunnel includes: a sprayed concrete section which is composed of concrete sprayed on the excavated surface of the natural ground; a fixing section which is inserted toward the natural ground from the inside of the sprayed concrete section, so as to integrate the natural ground and the sprayed concrete section together; a buffer section which is composed of an elastic member provided inside the sprayed concrete section in such a manner as to cover the concrete section, and which is thick enough to allow the displacement of the natural ground; and a lining concrete section which is provided in such a manner as to cover the inside of the buffer section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tunnel, a tunnel construction method, and a crack suppression device for lining concrete.

Natom method is known as a tunnel construction technique. The NATM (New Austrian Tunneling Method) method is one of the mainstream technologies in recent tunnel construction technology. In the Natom method, concrete is sprayed onto the excavated surface of the natural ground, and a rock bolt is inserted from the surface of the sprayed concrete toward the natural ground to integrate the ground with the sprayed concrete. On the other hand, tunnels are required to have excellent durability, and various construction techniques based on or improved from the Natom construction method have been proposed (see, for example, Patent Document 1).
JP-A-6-299793

  In concrete structures, technical development has been made to reduce cracks. There is no exception in tunnels, and there is a need for the development of technology that can further suppress cracking in lining concrete.

  The cause of cracking of the lining concrete is exemplified by voids existing in the crown of the tunnel, insufficient compaction of the concrete, insufficient filling pressure, insufficient curing, insufficient concrete strength, poor construction, external force, and the like. And in order to suppress cracking of lining concrete, improve the quality of concrete material (for example, use of expansion material, high-performance AE water reducing agent or use of non-steel fiber) and install curing equipment (for example, install wet equipment) Has been done. On the other hand, the Natom method is known as a tunnel construction technique. In the Natom method, however, in order to suppress the influence of external forces from the natural ground, lining concrete is placed after the displacement of the natural ground has converged. Is called. Therefore, hitherto, it was considered that the influence of the displacement of the natural ground on the lining concrete was small. However, since the displacement of the natural ground has only converged and is not zero, it is assumed that some displacement will occur even after lining. And if there is a displacement of the natural ground, there is a concern about the influence on the lining concrete.

  This invention makes it a subject to provide the technique which suppresses the crack of the lining concrete by the displacement of a natural ground in tunnel lining in view of the above-mentioned problem.

  In the present invention, in order to solve the above-described problems, a buffer portion that allows the displacement of the natural ground is provided between the excavation surface of the natural ground and the lining concrete.

  Specifically, the present invention includes a shotcrete portion made of concrete that is sprayed on a drilling surface of a natural ground, and is inserted toward the natural ground from the inside of the shotcrete portion, A fixed part that integrates the concrete part, and a buffer part made of an elastic member provided to cover the concrete part inside the shotcrete part, and has a thickness that allows the displacement of the natural ground A buffer part and a lining concrete part provided so as to cover the inside of the buffer part are provided.

The tunnel according to the present invention is characterized in that a buffer portion is provided on the outer side of the lining concrete (the natural ground side). And the buffer part consists of an elastic member, and has the thickness which accept | permits the displacement of a natural ground. Therefore, even if a natural ground displacement occurs, the external force from the natural ground to the lining concrete generated by the natural ground displacement is allowed, in other words, absorbed by the buffer portion. As a result, when the natural ground is displaced, an external force from the natural ground is allowed by the buffer portion, and cracking of the lining concrete is suppressed.

  The shotcrete part is composed of concrete sprayed on the excavation surface of the natural ground. The strength and thickness of the shotcrete part can be appropriately designed according to the scale and shape of the tunnel or the environment (temperature, humidity, etc.) in the tunnel. For example, a steel support may be provided in the shotcrete part. The fixing part is an integral part of the shotcrete and the natural ground, and can be constituted by a lock bolt used in a so-called natom method or a member having a function corresponding to the lock bolt. In the present invention, the inner side means the inner side of the tunnel. Therefore, the inside of the shotcrete portion is, in other words, the surface of the shotcrete portion on the inner side of the tunnel. On the other hand, the outer side surface of shotcrete is the surface on the natural ground side.

  A buffer part is comprised with the elastic member, and has the thickness which accept | permits the displacement of a natural ground. The thickness that allows the displacement of the natural ground means, in other words, the thickness that allows the external force generated by the displacement of the natural ground to be absorbed by the buffer portion made of an elastic member when the natural ground is displaced. It is. In addition, although it is preferable that the thickness of the buffer portion is a thickness that does not transmit the external force from the natural ground to the lining concrete, the thickness may be a thickness that can reduce the external force from the natural ground that is transmitted. Here, in the Natom method, in order to reduce the influence of external force from the natural ground, the lining concrete is placed after the displacement of the natural ground has converged. The confirmation of this convergence is, for example, according to the road tunnel observation / measurement guideline published by the Japan Road Association: “If the displacement speed is 1 mm / week or less can be confirmed about twice, the decision is finished. Measure the final displacement before lining and get approval. " Therefore, even when the displacement of the natural ground is considered in the long term, the displacement amount of the natural ground is predicted to be about several millimeters. The thickness of the buffer portion may be determined based on the predicted amount of displacement of the natural ground, or may be obtained through experiments or the like.

  The lining concrete part is provided inside the buffer part, that is, inside the tunnel. The strength and thickness of the lining concrete portion can be appropriately designed according to the scale and shape of the tunnel or the environment (temperature, humidity, etc.) in the tunnel.

  Here, the tunnel according to the present invention is provided between the buffer portion and the lining concrete, and is a sheet-like waterproof portion that prevents water discharged from the natural ground from entering the lining concrete. May be further provided. Thereby, deterioration by the water of lining concrete can be suppressed.

  Further, the tunnel according to the present invention includes a nail-like buffer portion fixing portion for fixing the buffer portion to the shotcrete portion, and the buffer portion fixing portion by covering a head portion of the buffer portion fixing portion. The protection part which prevents that the head of this is contacting the said lining concrete directly can be set as the structure further provided. And the said buffer part can be comprised with a sheet-like elastic member.

As described above, according to the buffer portion, it is possible to allow displacement of the natural ground, and as a result, cracking of the lining concrete can be suppressed. The buffer portion can be constituted by, for example, a sheet-like elastic member, and in this case, the buffer portion can be fixed to the shotcrete by a nail-like buffer fixing portion. Here, since the nail-like buffering fixing portion needs to be strong enough to be driven into the concrete, the covering concrete may be damaged when the head of the buffering fixing portion comes into contact with the covering concrete. Further, if the natural ground is displaced, there is a concern that an external force from the natural ground is concentrated on the contact portion between the head portion of the buffering fixing portion and the lining concrete portion. Therefore, in the tunnel according to the present invention, a protection part is provided in order to suppress cracking of the lining concrete by the buffering fixing part. In addition, it is preferable that the protection part has a thickness that allows displacement of the natural ground.

  Here, the present invention may be a tunnel construction method for constructing the tunnel described above. Specifically, the present invention is an excavation process for excavating a natural ground, a concrete spraying process for spraying concrete onto an excavation surface of the natural ground excavated in the excavation process, and a spraying process in the concrete spraying process. A fixed part installation step of installing a fixed part that integrates the natural ground and the shotcrete part from the inside of the shotcrete part made of concrete to the natural ground, and A buffer part made of an elastic member so as to cover the concrete part inside the shotcrete part integrated with the natural ground, and provided with a buffer part having a thickness allowing the displacement of the natural ground An installation step and a lining concrete placing step for providing a lining concrete portion so as to cover the inside of the buffer portion provided in the buffer portion installation step. According to the tunnel construction method according to the present invention, cracking of lining concrete can be suppressed. The tunnel construction method according to the present invention may further include the step of providing the waterproof part, the buffer part fixing part, and the protection part described above.

  Moreover, this invention is good also as a crack suppression apparatus of the lining concrete provided with the buffer part which comprises the tunnel mentioned above. Specifically, the present invention is a crack suppression device that suppresses cracking of lining concrete so that the concrete portion is covered inside a shotcrete portion made of concrete that is sprayed on a ground excavation surface. It is a buffer part made of an elastic member provided, and is a crack suppression device for lining concrete made of a sheet-like buffer part having a thickness allowing the displacement of the natural ground. By using the cracking suppression apparatus for lining concrete according to the present invention for a tunnel, cracking of the lining concrete can be suppressed. In addition, the cracking suppression apparatus of the said lining concrete may further be equipped with the sheet-like waterproof part mentioned above, the fixing | fixed part for buffer parts, and the protection part.

  ADVANTAGE OF THE INVENTION According to this invention, in the tunnel lining, the technique which suppresses the crack of the lining concrete by the displacement of a natural ground can be provided.

  DESCRIPTION OF EMBODIMENTS Embodiments of a tunnel, a tunnel construction method, and a lining concrete crack suppression device according to the present invention will be described.

<Overview>
First, the outline of the tunnel of the embodiment will be described together with the technical background. In tunnel lining, improvement in durability is required. In recent years, there have been particular demands for cracking prevention of concrete, filling properties (gap on the back of the lining), compaction of concrete, and improvement of appearance (performance). Therefore, the present inventor carried out daily technological development of a tunnel in order to achieve such a requirement, and obtained one hypothesis that “stress due to ground displacement acts on the lining and cracks occur”. . In recent years, the Natom method, which is widely used as a tunnel construction technique, has been lining after the displacement has converged to some extent, so there has been no one who advocates such a temporary construction. However, since the displacement is not zero and the lining is not performed, it is estimated that there is an influence of the long-term displacement. Then, this inventor decided to provide the shock absorbing material which absorbs the external force from the natural ground by the displacement of natural ground on the outer side of lining concrete. Hereinafter, the tunnel according to the embodiment will be described.

<Configuration>
FIG. 1 shows a cross-sectional view of a tunnel according to an embodiment. FIG. 2 shows an enlarged cross-sectional view in which the buffer member and the like are enlarged. As shown in FIG. 1 and FIG. 2, the tunnel according to the embodiment includes shotcrete 2, rock bolt 3, cushioning material 4, waterproof sheet 5, lining concrete 8, concrete nail 6, A protective member 7 is provided.

  The shotcrete 2 is formed by being sprayed on the excavation surface of the natural ground 1, covers the excavation surface, and supports the natural ground 1. The rock bolt 3 is inserted into the natural ground 1 through the shotcrete 2. In the drawing, the number of lock bolts 3 is omitted. It is necessary to design the number of the rock bolts 3 so that the shotcrete 2 and the natural ground 1 can be integrated reliably. Moreover, you may provide the steel support construction which supports the natural ground 1 with shotcrete 2.

  The buffer material 4 is provided inside the shotcrete 2 so as to cover the shotcrete 2. The cushioning material 4 is made of an elastic member and has a thickness that allows displacement of the natural ground 1. Thereby, when the natural ground 1 is displaced, the shock absorbing material 4 absorbs the external force generated by the displacement of the natural ground 1, so that the external force from the natural ground 1 is prevented from being transmitted to the lining concrete 8. Is done. As a result, cracking of the lining concrete 8 is suppressed.

  The waterproof sheet 5 is attached to the inner surface of the cushioning material 4, and suppresses the water (mainly spring water) discharged from the natural ground 1 from entering the lining concrete 8. Thereby, deterioration by the water of the lining concrete 8 can be suppressed. The concrete nail 6 corresponds to the buffer part fixing part of the present invention, and fixes the buffer material 4 and the waterproof sheet 5 to the sprayed concrete. The buffer material 4 and the waterproof sheet 5 may be integrally formed by sticking each other. In addition, it is good also as the crack suppression apparatus of the lining concrete which concerns on this invention by processing the buffer material 4 mentioned above into the suitable magnitude | size which is easy to stick on the shotcrete 2. Moreover, you may form the buffer material 4 and the waterproof sheet 5 integrally, and what was formed in this way is corresponded to the crack suppression apparatus of the lining concrete which concerns on this invention.

  The protection member 7 protects the head of the concrete nail 6. If the head of the concrete nail 6 contacts the lining concrete 8, the lining concrete 8 may be damaged. Moreover, if the natural ground 1 is displaced, there is a concern that an external force is concentrated on the contact portion between the head of the concrete nail 6 and the lining concrete 8. The protective member 7 prevents the harmful effects that may occur when the head of the concrete nail 6 contacts the lining concrete 8. The protective member 7 is preferably made of an elastic member and has a thickness that allows displacement of the natural ground 1.

  The lining concrete 8 is provided inside the waterproof sheet 5, that is, inside the tunnel well. The strength and thickness of the lining concrete 8 can be appropriately designed according to the scale and shape of the tunnel or the environment (temperature, humidity, etc.) in the tunnel.

Next, the operation and effect of the tunnel according to the above-described embodiment will be described based on the drawings while comparing with the conventional tunnel. First, the principle that cracks occur due to ground displacement will be described. FIG. 3A is a conceptual diagram in which cracks are generated due to the stress accompanying ground displacement acting on the lining when there is no gap in the crown portion. Moreover, FIG. 3B shows a conceptual diagram in which cracks are generated due to the stress accompanying ground displacement acting on the lining when there is a gap in the crown portion. P _1, P ₂ denotes the external force from the natural ground displacement, _{P'1, P'2} shows the resistance. The resistance force is a force obtained when the lining concrete 8 is integrated with the natural ground 1 by the lock bolt. In the natom method, the lining concrete 8 and the natural ground 1 are integrated by a rock bolt, and the natural ground 1 is supported. Accordingly, the balance between the external force from the natural ground 1 and the resistance force by the lining concrete 8 is lost, that is, when the external force from the natural ground 1 is generated due to the natural ground displacement, the external force exceeds the resistance force, It is considered that the difference between the two acts on the lining concrete as a tensile stress and causes cracking of the lining concrete. Note that when there is no gap in the crown portion as shown in FIG. 3A, only one crack is generated, whereas when there is a gap in the crown portion as shown in FIG. 3B, there are three cracks. There are places. This is because the resistance force P ′ ₂ becomes smaller than the resistance force P ′ ₁ due to the presence of voids in the crown portion. That is, the external force (P ₁ or P ₂₎ and the resistance difference _(P'1 or _P'2) and is considered to be equivalent to tensile stress, the void is present in the crown portion, since the resistance is reduced Tensile stress increases, and as a result, cracks are likely to occur. Therefore, conventionally, technological development for eliminating the gap in the crown portion has been advanced. The tunnel shown in FIGS. 3A and 3B is a model of a conventional tunnel, and a waterproof sheet 5 is provided outside the lining concrete 8. The waterproof sheet 5 is formed by bonding a waterproof film (thickness 0.8 mm) and a protective film (3 mm) for preventing damage to the waterproof film.

Next, the principle that cracks are suppressed in the tunnel according to the embodiment will be described with reference to the drawings. Here, FIG. 4A shows the relationship between the external force and the resistance force when placing the lining concrete. FIG. 4B shows the relationship between the external force and the resistance force when an external force is generated due to ground displacement. 4A and 4B, the cushioning material 4 having a thickness of 10 mm is provided outside the waterproof sheet 5. The waterproof sheet 5 has a thickness of 3.8 mm used in the conventional tunnel shown in FIGS. 3A and 3B. As shown in FIG. 4A, at the time of placing the lining concrete, the external force due to ground displacement is zero, and the relationship shown in Equation 1 is established. In this case, P ′ corresponds to the lining concrete pressure and the filling pressure (semi-fluid). From the past results, the resistance (concrete pressure, filling pressure) is about 5 t / m ² .
P '> P = 0 ... Equation 1

In the embodiment shown in FIG. 4B, if the ground cover displacement occurs after the lining concrete is placed, cracks occur in the lining concrete 8 due to the influence of the external force due to the ground displacement (see FIGS. 3A and 3B). By providing the material 4, the ground displacement amount is absorbed by the buffer material 4, and the occurrence of cracks in the lining concrete 8 is suppressed. That is, even if the displacement of the natural ground is 5 mm, external force is absorbed by the buffer material 4 by providing the buffer material 4 having a thickness of 10 mm. For example, it is predicted that the thickness of the buffer material 4 changes from 10 mm to 7 mm, and the thickness of the waterproof sheet 5 changes from 3.8 mm to 1.8 mm. Therefore, the decrease in thickness of the cushioning material 4 and the waterproof sheet 5 corresponds to the displacement of the natural ground 5 mm. From the above, when a natural ground displacement occurs, the relationship shown in Equation 2 is established. In this case, P ′ corresponds to a resistance force (solid) to an external force and its own weight.
P> P ′ <crack resistance (f _tk : tensile strength)

<Tunnel construction method>
Next, a tunnel construction method according to the above-described embodiment will be described. FIG. 5 shows a tunnel construction procedure according to the embodiment. In addition, the tunnel construction method according to the present embodiment can be suitably used for the Natom method. In step S01, excavation is performed. Examples of the excavation method include a conventional blast excavation method using explosives, a mechanical excavation method using a free-section excavator, and the like. When excavation is completed, the process proceeds to step S02.

  In step S02, concrete is sprayed on the excavation surface. Thereby, shotcrete 2 is formed. Subsequently, in step S03, the lock bolt 3 is installed. Specifically, a plurality of holes are made in the shotcrete 2 and the lock bolts 3 are driven into the holes. As a result, the natural ground 1 and the shotcrete 2 are integrated by the lock bolt 3. When the driving of the lock bolt 3 is completed, the process proceeds to step S04.

In step S04, the cushioning material 4 and the waterproof sheet 5 are attached. In this embodiment, first, the buffer material 4 is attached by the concrete nail 6, and the waterproof sheet 5 is attached by the concrete nail 6 so as to cover the buffer material 4. The cushioning material 4 and the waterproof sheet 5 may be formed integrally. By attaching the cushioning material 4 and the waterproof sheet 5, it is possible to absorb external force from the natural ground 1 and to prevent water from the natural ground 1 from entering the lining concrete.

  Here, the attachment procedure of the cushioning material 4 and the attachment procedure of the waterproof sheet 5 will be described in more detail based on the drawings. FIG. 6 shows a cross-sectional view of the state in which the cushioning material 4 is attached to the shotcrete 2. FIG. 7 shows a front view of the state in which the cushioning material 4 is attached to the shotcrete 2. In this aspect, the end part of the adjacent buffer material 4 is lapped by 100 mm to 200 mm, the wrapped part is pressed by the band iron 21, and the concrete nail 6 is passed through the band iron 21 and the buffer material 4, thereby the buffer material 4. Is fixed to shotcrete 2. Further, a protective member 7 made of butyl rubber is provided so as to cover the head of the concrete nail 6. The protective member 7 is 50 mm square and 10 mm thick. The thickness of the protection member 7 is designed in consideration of the natural ground displacement, but in this embodiment, the thickness is designed according to the thickness of the cushioning material 4.

  FIG. 8 shows a cross-sectional view of the state in which the waterproof sheet 5 is attached to the shotcrete 2. FIG. 9 shows a front view of the state in which the waterproof sheet 5 is attached to the shotcrete 2. In this embodiment, even when the waterproof sheet 5 is attached, the end of the waterproof sheet 5 is wrapped from 50 mm to 100 mm, the wrapped portion is pressed by the band iron 21, and the band iron 21, the cushioning material 4 and the waterproof sheet 5 are made of concrete. By passing the nail 6 through, the waterproof sheet 5 is fixed to the sprayed concrete 2. Further, a protective member 7 made of butyl rubber is provided so as to cover the head of the concrete nail 6. Similarly, the protective member 7 is 50 mm square and 10 mm thick. The thickness of the protective member 7 is designed in consideration of the natural ground displacement, but in this embodiment, the thickness is designed according to the thickness of the cushioning material 4.

  FIG. 10 shows an enlarged cross-sectional view of the head of the lock bolt 3. In this aspect, after attaching the lock bolt 3 so that the head of the lock bolt 3 is not exposed, the protective concrete 22 may be further sprayed so as to cover the head of the lock bolt 3. This prevents the head of the lock bolt 3 from coming into direct contact with the cushioning material 4. Reference numeral 23 denotes an H-shaped steel support. When the attachment of the cushioning material 4 and the waterproof sheet 5 is completed, the process proceeds to the next step S05.

  In step S05, the lining concrete 8 is placed. Specifically, concrete for lining concrete is cast so as to cover the inner surface of the waterproof sheet 5, and a wall surface in the tunnel mine is formed.

In addition, about the construction methods other than what was mentioned above, the conventional technique can be used suitably. For example, the crown can be compacted by a high quality tunnel lining pressure retention top end compaction system. Horizontal placement can be performed by a concrete horizontal press-fitting method. In order to completely fill the crown, a concrete filling pressure management system and a concrete horizontal press-fitting method may be employed. A parasol 30 mist method can be used for curing. A bulkhead balloon can be used for curing after tunnel penetration. The placement span can be, for example, a standard 10.5 m. Concrete mix can be, for example, on-site mix 21-15-20, maximum aggregate particle size = 20 mm. The casting slump can be 13 cm to 14 cm up to the arch shoulder and 16 cm to 17 cm at the crown. The strength of the concrete may be targeted at 30 N / mm ² with standard curing. The underground humidity is preferably 80% or more. For example, the humidity can be secured by watering the roadbed. In addition, when there is spring water, you may make it secure in a natural environment using this. The curing time (unframed time) can be, for example, 18 hours to 20 hours (1 placement / 2 days).

  Note that the concrete horizontal press-in method is to add a blow-up port that can be pressed into the arch, shortening the amount and time required for pouring from the crown blow-up port, and improving the concrete filling performance. Technology. Moreover, the parasol 30 miss and the construction method are techniques for performing wet curing by mistake and jetting by suspending a movable parasol with a sheet attached to the framework of a lightweight pipe to the top of the lining.

[Compression test of cushioning material]
Next, a compression amount measurement test (hereinafter referred to as a compression test) of the buffer material used in the tunnel according to the present embodiment will be described. FIG. 11 shows an outline of the compression test. As shown in the figure, in this compression test, the shock-absorbing material 4 to be tested is placed on the test table 31, and the amount of compression of the shock-absorbing material 4 is measured by applying a load. In this compression test, a needful mat (APS-10) manufactured by Tanaka Co., Ltd. was used as a test object, a buffer material 4 having a thickness of 10 mm (test case 1), and a buffer material 4 having a thickness of 5 mm (test case 2). ) Was used. In addition, all measured in the state in which the waterproof sheet 5 was piled up. The waterproof sheet 5 is composed of a protective member made of a waterproof layer having a thickness of 0.8 mm and a nonwoven fabric having a thickness of 3 mm.

Here, FIG. 12 shows a graph of the stress-compression amount curve in the test case 1. FIG. 13 shows a graph of a stress-compression curve in Test 2. In this compression test, the load (loading stress) was applied up to 10 t / m ² . For test case 1, the loading stress is 10
At t / m ² , the compression amount is 7.75 mm, which is less than the thickness 10 mm of the buffer material 4. Therefore, even if a loading stress of 10 t / m ² is generated due to the displacement of the natural ground, the cushioning material 4
Can absorb external force from natural ground. On the other hand, regarding the test case 2, the compression amount is 6.50 mm at a loading stress of 10 t / m ² , which exceeds the thickness of the buffer material 4. Therefore, if the external force is temporarily predicted to be about 10 t / m ² from the natural ground, it is necessary to increase the thickness of the cushioning material 4. However, the load stress normally expected is considered to be about 5 t / m ² . Therefore, it is clear that the shock absorber 4 of the test case 1 can tolerate external force from the natural ground. Further, in the case of the buffer material 4 of the test case 2, the amount of compression slightly exceeds the thickness 5 mm of the buffer material 4. However, in this test, since the nonwoven fabric (3 mm) as the protective member is provided on the waterproof sheet 5, it is considered that both the cushioning material 4 and the waterproof sheet 5 can absorb the external force of the natural ground. From the above, the thickness of the cushioning material 4 can be appropriately designed based on the compression amount of the cushioning material 4 and the predicted ground displacement (external force).

  In the tunnel according to the embodiment described above, the buffer material 4 is provided between the natural ground 1 and the lining concrete 8, and the buffer material 4 is made of an elastic member, and has a thickness that allows the displacement of the natural ground 1. Have. Thereby, even when the displacement of the natural ground 1 occurs, the external force from the natural ground 1 against the lining concrete 8 is absorbed by the buffer material 4. As a result, when the natural ground 1 is displaced, the influence of external force from the natural ground 1 on the lining concrete 8 is reduced, and cracking of the lining concrete 8 can be suppressed.

  As described above, the tunnel and the tunnel construction method according to the embodiment have been described. However, the tunnel, the tunnel construction method, and the crack prevention device for lining concrete are not limited to these, and may include combinations of these as much as possible. it can.

A sectional view of a tunnel concerning an embodiment is shown. The expanded sectional view which expanded the buffer member etc. is shown. The conceptual diagram which the crack accompanying a stress with a natural ground displacement acting on a lining when a gap does not exist in a crown part occurs is shown. The conceptual diagram in which the stress accompanying a ground displacement acts on the lining when there is a gap in the crown portion and cracks occur is shown. The relationship between external force and resistance force during lining concrete placement is shown. The relationship between external force and resistance force when external force is generated due to ground displacement is shown. The construction procedure of the tunnel which concerns on embodiment is shown. Sectional drawing of the state which attached the shock absorbing material to the shotcrete is shown. The front view of the state which attached the shock absorbing material to the shotcrete is shown. Sectional drawing of the state which attached the waterproof sheet to shotcrete is shown. The front view of the state which attached the waterproof sheet to the shotcrete is shown. The expanded sectional view of the head of a lock bolt is shown. An outline of the compression test is shown. The graph of the stress-compression amount curve in Test Case 1 is shown. The graph of the stress-compression amount curve in Test Case 2 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Natural mountain 2 ... Shotcrete 3 ... Rock bolt 4 ... Buffer material 5 ... Waterproof sheet 6 ... Concrete nail 7 ... Protection member 8 ... Covering concrete

Claims (8)

A shotcrete section made of concrete blown to the excavation surface of the natural ground,
A fixed portion that is inserted from the inside of the shotcrete portion toward the natural ground, and integrates the natural ground and the shotcrete portion;
A buffer part made of an elastic member provided so as to cover the concrete part inside the shotcrete part, the buffer part having a thickness allowing the displacement of the natural ground;
A lining concrete part provided to cover the inside of the buffer part;
Tunnel with.   The sheet-like waterproof part which is provided between the said buffer part and the said lining concrete part, and suppresses that the water discharged | emitted from the said natural ground penetrate | invades into this lining concrete. tunnel. The buffer portion is made of a sheet-like elastic member,
A nail-shaped fixing part for the buffer part for fixing the buffer part to the shotcrete part,
The protective part which prevents that the head of the fixing part for buffering part directly contacts the lining concrete by covering the head of the fixing part for buffering part is provided. The described tunnel.   The tunnel according to claim 3, wherein the protection part has a thickness that allows displacement of the natural ground. Excavation process to excavate natural ground;
A concrete spraying step of spraying concrete onto the excavation surface of the natural ground excavated in the excavation step;
The fixing part installation process which installs the fixing part which unifies the ground and the shotcrete part from the inside of the shotcrete part made of the concrete sprayed in the concrete spraying process toward the ground When,
A buffer part made of an elastic member so as to cover the concrete part inside the shotcrete part integrated with the ground in the fixing part installation step, and having a thickness that allows the displacement of the ground A buffer part installation step of providing a buffer part having,
A lining concrete placing step for providing a lining concrete portion so as to cover the inside of the buffer portion provided in the buffer portion installation step,
A tunnel construction method comprising: A crack suppressing device for suppressing cracking of lining concrete,
A buffer portion made of an elastic member provided to cover the concrete portion inside the shotcrete portion made of concrete sprayed on the excavation surface of the natural ground, and has a thickness allowing the displacement of the natural ground Cracking control device for lining concrete consisting of a sheet-like buffer.   The crack of the lining concrete according to claim 6, further comprising a sheet-shaped waterproof portion that is surface-connected to the inside of the buffer portion and prevents water discharged from the natural ground from entering the lining concrete. Suppression device. A nail-shaped fixing part for the buffer part for fixing the buffer part to the shotcrete part,
The protection part which prevents that the head of the fixing part for buffering part directly contacts the lining concrete by covering the head of the fixing part for buffering part is provided. The lining concrete crack suppression apparatus as described.

Images