JP7125550B2 - SUPPORT STRUCTURE AND CONSTRUCTION METHOD FOR TWO-STAGE HIGH-SPEED CLOSING TUNNEL WITH INVERTED ARCH - Google Patents

Description

TECHNICAL FIELD The present invention relates to the technical field of tunnel construction, and more particularly to a support structure and construction method for a two-stage high-speed closing tunnel with inverted arches.

Tunnels are structures constructed underground and are widely used in fields such as transportation, mining, water conservancy, and national defense. Current tunnels generally use the New Austrian Tunneling Method, and the support structure is a composite lining structure, with vaults, inverted arches and sidewalls along the tunnel's circumferential direction, and radially It has an outer primary lining, an inner secondary lining along and a waterproof layer positioned between the primary and secondary linings.

With the rapid development of tunnel and underground engineering in southwestern China, the number of mountain railways and ultra-long tunnels has gradually increased, and the length of tunnel construction through high ground stress and soft surrounding rocks has increased accordingly. . The ground stress is high, the rock is soft, and the deformation of the tunnel is large, making it difficult to control during construction. If there is even a little carelessness during construction, deformation and landslide disasters are likely to occur. Moreover, in order to construct a tunnel in a submerged zone of extruded soft rock, which poses the same intractable problems in terms of structural design and subsequent maintenance of the tunnel, it is necessary to ``strength overcomes stiffness'' and ``softness overcomes stiffness''. There are two methods of controlling the "Stiff and stiff" means to resist the enormous squeezing forces of the formation by setting up strong rigid supports soon after drilling begins. “Flexible and rigid” means that by starting excavation and installing flexible supports first, a certain amount of deformation of the stratum is allowed, and then rigid supports are installed after the ground stress is released. to re-install. For these two support philosophies, the main corresponding technical measures are pre-strengthening of surrounding rocks, initial support of heavy steel frames, and corresponding "rigid support" such as early application of secondary lining. ”, and corresponding “flexible supports” such as rock bolts, stress relief of advanced shafts, etc. using flexible steel frames. Clearly, the latter fits the principles of the New Austrian Tunneling Method. The terms ``rigid'' and ``soft'' here are two relative concepts. The implication is to rationally release the deformation of the surrounding rock to reduce the forces acting on the supporting structure. However, "softness" is based on ensuring that the support structure does not lose its effectiveness, and once it loses its effectiveness, deformation and landslides will occur. Support structures in the prior art consist of rigid primary linings that are directly and intimately bonded to the surface of the tunnel passage, but due to the high stresses induced by the rock formations surrounding the tunnel passage, the primary lining will always remain intact. Explosions and spalling of concrete, distortion deformation of steel arches, etc. occur. If the steel arch is deformed, it will enter the space for the secondary lining in the next process, making it impossible to construct the secondary lining. Therefore, the rigid primary lining that has already been constructed must be dismantled, and a new rigid primary lining must be constructed. This not only greatly increases the process cost and construction risk, but also greatly prolongs the construction period.

One object of the present invention is to provide a support structure for a two-stage high-velocity closed tunnel with inverted arches.

Another object of the present invention is to provide a method for constructing a support structure for a two-stage high-velocity closed tunnel with inverted arches.

To achieve the objects of the present invention, a support structure for a two-stage fast closing tunnel with inverted arch according to the present invention comprises a vault at the top, an inverted arch at the bottom and side walls on both sides along the circumference of the tunnel. a primary lining of a first layer on the outer layer, a secondary lining on the inner layer, and a waterproof layer provided between the primary lining of the first layer and the secondary lining along the radial direction of the tunnel; comprises geotextile and waterproof panels, said first layer of primary lining comprising a first layer of upper step primary lining and a first layer of lower step primary lining, said first layer of upper step primary the lining comprising a first upper step steel arch, said first layer lower step primary lining comprising a first lower step steel arch, said first upper step steel arch and said first lower step Steel arches join head-to-tail to form a closed ring, said support structure comprises a second layer of primary lining disposed between said first layer of primary lining and said waterproof layer; Two layers of primary lining are provided along the radial direction of the tunnel, said second layer of primary lining comprising a second layer of upper step primary lining and a second layer of lower step primary lining; the upper step primary lining of the layer comprising a second upper step steel arch, said lower step primary lining of said second layer comprising a second lower step steel arch, said second upper step steel arch and said second lower step steel arch join head-to-tail to form a closed ring.

Preferably, said first upper step steel arch comprises a first sidewall steel arch, a first top steel arch, a second sidewall steel arch connected in sequence, and said first lower step The steel arch comprises a third sidewall steel arch, a fourth sidewall steel arch, a first bottom steel arch, a fifth sidewall steel arch, a sixth sidewall steel arch connected in sequence. , the end of the first end of the third side wall steel arch and the first side wall steel arch are connected, the second end of the third side wall steel arch extends downward; Four side wall steel arches are connected to the sides of the first end of the third side wall steel arch, connecting the ends of the first end of the sixth side wall steel arch and the second side wall steel arch. The arches are connected, the second end of the sixth side wall steel arch extending downwards, and the fifth side wall steel arch flanking the first end of the sixth side wall steel arch. Connected.

Preferably said second upper step steel arch comprises a first sidewall steel support, a first top steel support and a second sidewall steel support connected in sequence, said second lower step steel arch comprises a third sidewall steel support, a first bottom steel support and a fourth sidewall steel support connected in sequence, said first sidewall steel support connecting with said third sidewall steel support, said A second sidewall steel support connects with the fourth sidewall steel support.

Preferably, a pre-deformation space of the first layer primary lining is provided between the first layer primary lining and the second layer primary lining, and between the second layer primary lining and the waterproof layer. is provided with a pre-deformation space for the primary lining of the second layer, and the pre-deformation amount of the pre-deformation space of the primary lining of the first layer is greater than the pre-deformation amount of the pre-deformation space of the primary lining of the second layer.

Preferably, said first layer upper step primary lining further comprises an arch lock bolt unit, said arch lock bolt unit comprising a plurality of coupled hollow lock bolts with exhaust devices, and a plurality of said coupled hollow locks Bolts are arranged in the vault along the circumferential and longitudinal directions of the tunnel.

Preferably, the support structure further comprises a reinforcing rock bolt unit, the reinforcing rock bolt unit comprising a plurality of elongated rock bolts of the arches, a plurality of upper step side wall elongated lock bolts, and a plurality of lower step side wall elongated lock bolts. An elongated rock bolt, a plurality of tunnel bottom elongated rock bolts, a plurality of said arched elongated rock bolts disposed in said vault along the tunnel's circumferential and longitudinal directions, and a plurality of said upper steps. Elongated rock bolts on sidewalls are disposed on the sidewalls on both sides of the upper step of the tunnel along the circumferential and longitudinal directions of the tunnel, and a plurality of elongated rock bolts on the lower step sidewalls extend in the circumferential and longitudinal directions of the tunnel. and a plurality of the tunnel bottom elongated rock bolts are disposed at the bottom of the tunnel along the circumferential and longitudinal directions of the tunnel.

In order to achieve another object of the present invention, the method for constructing the support structure of the two-stage high-speed closing tunnel with inverted arch according to the present invention comprises the forward support of the upper step and the forward-reinforcing rock bolt of the upper step. step of providing, step of excavating the upper step body of the tunnel, step of providing the first layer upper step primary lining and spraying concrete, step of excavating the lower step body of the tunnel, first layer lower step primary lining and spraying concrete; installing long rock bolts on the side walls of the lower step and long rock bolts on the bottom of the tunnel; providing a second layer of primary lining on the lower step, spraying concrete, and backfilling the bottom of the tunnel installation of long rock bolts on the side walls of the upper step and long rock bolts of the vault; installation of the second layer of the upper step primary lining and spraying concrete; casting of the inverted arch and filling of the inverted arch A step of placing a placement, and a step of placing a secondary lining.

Preferably, in the construction method, it is determined whether or not the tunnel has been excavated, and if the tunnel has not been penetrated, the long rock bolt of the side wall of the upper step and the long rock bolt of the vault are driven in, and in the vertical direction of the tunnel the step of providing a pre-receiving support of the upper step and a rock bolt for reinforcing the pre-receiving of the upper step; excavating the upper step body of the tunnel; and providing the upper step primary lining of the first layer. a step of spraying concrete; a step of excavating the lower step body of the tunnel; providing the first layer of lower step primary lining and spraying concrete; The steps of installing length rock bolts, installing the lower step primary lining of the second layer, spraying concrete, and backfilling the bottom of the tunnel are carried out in sequence to form short steps to quickly close the ring structure. Move construction forward cyclically.

Preferably, the forward receiving support of said upper step comprises a plurality of forward receiving injection tubules, and a plurality of said forward receiving injection tubules are arranged along the circumferential direction and the longitudinal direction of the tunnel.

Preferably, said upper step anticipatory reinforcing rock bolt comprises a plurality of longitudinal rock bolts, said longitudinal rock bolts being arranged on the tunnel face of the tunnel upper step along the longitudinal direction of the tunnel. be done.

According to the support structure of the two-stage high-speed closing tunnel with inverted arch of the present invention, the combination of the primary lining of the first layer and the primary lining of the second layer effectively improves the stress distribution in the inner circumference of the tunnel, It can reduce the extent of fracture of surrounding rocks, effectively solve the limitations of tunnel mechanization construction methods due to adverse geological conditions such as high ground stress, large deformation of soft rock, and safety risks during tunnel construction. can be greatly reduced, and safe, high-speed, economical and rational construction can be performed. A support structure for a two-stage fast closing tunnel with inverted arches comprising a first upper step steel arch, a first lower step steel arch, a second upper step steel arch and a second lower step steel arch can be divided into multiple steel arches for convenient transport and storage in mechanized construction. In the support structure of the two-stage high-speed closing tunnel with inverted arch, a deformation space is preconfigured between the primary lining of the first layer and the primary lining of the second layer, and between the primary lining of the second layer and the waterproof layer A pre-deformation space for the primary lining of the second layer is provided in between, which provides a permissible space for the deformation of the surrounding rocks to guarantee the maximum permissible deformation of the surrounding rocks in space. can. In the support structure of a two-stage fast-closing tunnel with an inverted arch, multiple rock bolts of different standards can be installed in the circumferential direction of the tunnel, thus limiting and constraining the deformation of the surrounding rock in the circumferential direction of the tunnel. It is possible to increase the strength of the rock around the lock part to prevent the tunnel from collapsing.

According to the construction method of the support structure of the two-stage high-speed closing tunnel with inverted arch, the combination method of double layer support and long and short rock bolts is used. In addition, a two-step high-speed construction method is adopted, and the deformation amount of the tunnel, which undergoes large deformation, can be decomposed into each construction step. And by adopting step-by-step control and fast closing method, the total deformation amount of the surrounding rock can be effectively controlled, which greatly reduces the safety risk during tunnel construction, making it safe, fast and economical. And the purpose of reasonable tunnel construction can be realized.

[0013] Figure 4 illustrates a cross-section of a support structure according to an embodiment of the invention; Fig. 3 shows a cross section of a first layer primary lining and a second layer primary lining according to an embodiment of the present invention; 4 is a flowchart of a construction method according to an embodiment of the invention; Fig. 3 shows a cross-section of a support structure when carrying out steps 1, 2 and 3 of a construction method according to an embodiment of the present invention; FIG. 4 is a cross-sectional view of a support structure when performing steps 4, 5 and 6 of the construction method according to an embodiment of the present invention; Fig. 3 shows a cross-section of a support structure when performing step 7 of a construction method according to an embodiment of the invention; Fig. 3 shows a cross-section of a support structure when performing step 8 of the construction method according to an embodiment of the invention; Fig. 3 shows a cross-section of a support structure when performing step 9 of the construction method according to an embodiment of the invention; Fig. 3 shows a cross-section of the support structure when performing step 10 of the construction method according to an embodiment of the invention; Fig. 3 shows a cross-section of the support structure when performing step 11 of the construction method according to an embodiment of the invention;

Hereinafter, the present invention will be described in more detail based on the drawings and embodiments.

<Embodiment of Support Structure for Two-Stage High-Speed Closed Tunnel with Inverted Arch>
See Figures 1-2. 1 is a cross-sectional view of a support structure according to an embodiment of the invention, and FIG. 2 is a cross-sectional view of a first layer primary lining and a second layer primary lining according to an embodiment of the invention. . The support structure of this embodiment comprises a vault at the top, an inverted arch at the bottom and side walls on both sides along the circumference of the tunnel. In addition, along the radial direction of the tunnel, a first layer primary lining 1 in the outer layer, a secondary lining 3 in the inner layer, and a waterproof layer provided between the first layer primary lining 1 and the secondary lining 3 are provided. and the waterproof layer comprises geotextile and waterproof panels. The first layer of primary lining 1 comprises a first layer of upper step primary lining and a first layer of lower step primary lining. The upper step primary lining of the first layer and the lower step primary lining of the first layer are vertically divided at the step boundary line of the tunnel. The upper step primary lining of the first layer comprises a first upper step steel arch located above the step boundary. The lower step primary lining of the first layer comprises a first lower step steel arch located below the step boundary. The first upper step steel arch and said first lower step steel arch join head-to-tail to form a closed ring.

The support structure comprises a second layer of primary lining provided between the first layer of primary lining 1 and the waterproof layer, the second layer of primary lining being provided along the radial direction of the tunnel. The second layer of primary lining comprises a second layer of upper step primary lining and a second layer of lower step primary lining, the second layer of upper step primary lining comprises a second layer of step above the step boundary. comprising an upper step steel arch, the second layer lower step primary lining comprising a second lower step steel arch located below the step boundary, the second upper step steel arch and said second The lower step steel arches of the are joined head-to-tail to form a closed ring.

The first upper step steel arch comprises in sequence a first sidewall steel arch 11, a first top steel arch 12, a second sidewall steel arch 13 connected by a steel frame, a first The side wall steel arch 11 and the second side wall steel arch 13 are symmetrically installed on both left and right sides of the first top steel arch 12 . The first lower step steel arch comprises a third sidewall steel arch 14, a fourth sidewall steel arch 15, a first bottom steel arch 16, a fifth sidewall steel arch connected by a steel frame. It has an arch 17 and a sixth side wall steel arch 18 in that order. A fourth sidewall steel arch 15 and a fifth sidewall steel arch 17 are symmetrically installed on both left and right sides of the first bottom steel arch 16 . The end of the first end of the third side wall steel arch 14 is connected to the first side wall steel arch 11, the second end of the third side wall steel arch 14 extends downward, The side of the first end of the side wall steel arch 14 is connected to one end of the fourth side wall steel arch 15 remote from the first bottom steel arch 16 . The end of the first end of the sixth side wall steel arch 18 is connected to the second side wall steel arch 13, the second end of the sixth side wall steel arch 18 extends downwards and the sixth side wall steel arch 18 extends downwards. side wall steel arch 18 is connected to one end of the fifth side wall steel arch 17 remote from the first bottom steel arch 16 .

The second upper step steel arch comprises a first sidewall steel support, a first top steel support, a second sidewall steel support connected in sequence by a steel frame, the first sidewall steel support and a second The side wall steel supports are placed symmetrically on both left and right sides of the first top steel support. The second lower step steel arch comprises a third sidewall steel support 24, a first bottom steel support 25, a fourth sidewall steel support 26 connected in sequence by a steel frame to form a third sidewall steel support. 24 and a fourth side wall steel support 26 are placed symmetrically on both left and right sides of the first bottom steel support 25 . A first sidewall steel support connects with a third sidewall steel support through a connecting steel frame, and a second sidewall steel support connects with a fourth sidewall steel support 26 through a connecting steel frame.
A pre-deformation space 4 for the first layer primary lining is provided between the first layer primary lining 1 and the second layer primary lining, and a second layer primary lining space 4 is provided between the second layer primary lining and the waterproof layer. A pre-deformation space 25 for the primary lining is provided. Here, the pre-deformation amount of the pre-deformation space 4 of the first layer primary lining is greater than the pre-deformation amount of the pre-deformation space 25 of the second layer primary lining. In this embodiment, the pre-deformation amount of the pre-deformation space 4 of the primary lining of the first layer is preferably 30 cm, and the pre-deformation amount of the pre-deformation space 25 of the primary lining of the second layer is preferably 15 cm. .

The upper step primary lining of the first layer further comprises an arch lock bolt unit, the arch lock bolt unit comprising a plurality of connecting hollow rock bolts 6 with exhaust devices, the plurality of connecting hollow rock bolts 6 being connected to the tunnel located in the vault along the circumference and longitudinal direction of the The coupling hollow lock bolt 6 has a length of 3 m, and one coupling hollow lock bolt 6 is driven at intervals of 1.2 m in the circumferential direction, and one coupling hollow lock bolt is driven at intervals of 1.0 m in the longitudinal direction. A bolt 6 is installed.

The support structure according to this embodiment further comprises a reinforcing rock bolt unit, which includes a plurality of arch elongated rock bolts 7, a plurality of side wall elongated lock bolts 8, and a plurality of tunnel bottom elongated locks. It has a bolt 9. A plurality of arched elongated rock bolts 7 are arranged in the vault along the circumferential and longitudinal directions of the tunnel. A plurality of side wall long rock bolts 8 are arranged on both side walls of the tunnel along the tunnel's circumferential direction and longitudinal direction, and both side walls are separated upper steps on both sides above and below the step boundary line. side walls and lower step side walls and correspondingly side wall long lock bolts 8 comprise upper step side wall long lock bolts and lower step side wall long lock bolts; An elongated rock bolt is located on the upper step sidewall and an elongated rock bolt on the lower step sidewall is located on the lower step sidewall. A plurality of elongated tunnel bottom rock bolts 9 are arranged in the tunnel bottom along the circumferential and longitudinal directions of the tunnel. The long lock bolt 7 of the arch portion is a resin lock bolt having a diameter of 25 mm and a length of 6 m. One resin rock bolt is installed at intervals of 1.2m. The long lock bolt 8 on the side wall and the long lock bolt 9 at the bottom of the tunnel are self-propelled lock bolts with a diameter of 32 mm and a length of 8 m. A traveling lock bolt is installed, and one self-propelled rock bolt is installed at an interval of 1.0 m in the vertical direction.

First layer primary lining 1 is sprayed with first upper step steel arch, first lower step steel arch, wire mesh, longitudinal connecting steel bars, connecting steel bars, pipe rock bolts 10 of upper and lower steps Constructed of concrete structure. The primary lining of the second layer consists of a shotcrete structure with second upper step steel arches, second lower step steel arches, wire mesh, longitudinal connecting steel bars, and connecting steel bars.

<Embodiment of Construction Method for Support Structure of Two-Stage High-Speed Closing Tunnel with Inverted Arch>
3 to 10, the construction method of the support structure of the two-stage high-speed closed tunnel with inverted arch according to the present invention includes the following steps.

In step S1, a pre-receiving support for the upper step and a pre-receiving reinforcing rock bolt for the upper step are driven. First, using a rock drill, a pre-receiving tremie tube 20 with a diameter of 42 mm and a length of 4.5 m is driven forward at a constant angle along the excavation outer contour of the vault. The pre-receiving small steel pipes 20 are constructed by connecting 3m in the vertical direction as one cycle. . Next, it is necessary to grout and reinforce the receiving tremie tube 20 at a predetermined pressure so that the grouting of the receiving tremie tube 20 is filled. Next, a rock drill is used to install a pre-receiving reinforcing rock bolt 30 on the face of the upper step. Here, the pre-receiving reinforcing rock bolt 30 is a glass fiber rock bolt, and the glass fiber rock bolt has a diameter of 22 mm and a length of 6 m. The plurality of fiberglass rock bolts are divided into a plurality of horizontal rows and a plurality of vertical rows, each horizontal row having a spacing of 1.5m and each vertical row having a spacing of 1.5m. For convenience of operation, draw horizontal and vertical auxiliary lines on the face of the upper step with a standard of 1.5m horizontal interval and 1.5m vertical interval, and horizontal and vertical auxiliary lines be placed across. Next, from all the intersections of the horizontal auxiliary lines and the vertical auxiliary lines, a plurality of intersections are selected to provide glass fiber lock bolts, and the horizontal distance between two adjacent glass fiber lock bolts is 3. 0.0 m and the vertical spacing between two adjacent fiberglass rock bolts is 3.0 m. The glass fiber rock bolts are connected and constructed in a cycle of 6.0 m above the vertical direction.

Next, in step S2, the upper step body of the tunnel is excavated. Specifically, a rock drill is used to drill and excavate the upper step body by weak blasting. During the excavation operation, the vault is excavated first, followed by the sidewalls. The excavation length of each cycle does not exceed the steel frame spacing of the two structures, i.e., 1.2 m, for a total excavation of 6 m through five excavations. Before excavating the side wall, two pipe type rock bolts 10 with a diameter of 42 mm and a length of 4.5 m were driven into the rock wall on both sides of the vault, and grout was injected into the pipe type rock bolts 10. , to prevent vault shrinkage and arch dropout.

Next, in step S3, a first layer of upper step primary lining is provided following the face of the upper step. After excavating the upper step body of the tunnel, the rock face of the upper step is first sprayed with concrete with a thickness of 4 cm in time. Then, again using a rock drill or anchor excavator, a joint hollow rock bolt 6 with a diameter of 22 mm and a length of 3 m with an exhaust system is installed in the arch of the tunnel and filled with grout. Two adjacent coupling hollow rock bolts 6 have a circumferential spacing of 1.2 m and a longitudinal spacing of 1.0 m. Next, the primary upper step steel arches of the first layer are installed. Before installing the primary upper step steel arch of the first layer, first connect the first side wall steel arch 11, the first top steel arch 12 and the second side wall steel arch 13 in order. A connecting steel frame connects between the first side wall steel arch 11 and the first top steel arch 12, and a connecting steel between the first top steel arch 12 and the second side wall steel arch 13. connected by a frame made of A steel arch assembler is then used to install the first layer upper step steel arch. Next, a wire mesh is installed, and the wire mesh, pipe type rock bolt 10, etc. are welded and fixed to the steel arch of the primary upper step of the first layer respectively, and then concrete is sprayed again to form the upper step of the first layer. The total thickness of the primary lining initial and recast concrete is 27 cm to ensure uniformity, compactness and no voids behind.

Next, in step S4, the lower step body of the tunnel is excavated. First, a rock drill is used to drill and then a weak blast is used to excavate the lower step. The excavation length of each cycle does not exceed the steel frame spacing of the five structures, i.e. not more than 3m, for a total excavation of 6m through two excavations. When excavating the body of the lower step, two pipe-type rock bolts 10 with a diameter of 42 mm and a length of 4.5 m are driven into the rock wall from both sides of the reverse arch, and grout is injected into the pipe-type rock bolts 10. .

Next, in step S5, a first layer of lower step primary lining is provided following the face of the lower step. After excavating the lower step body of the tunnel, the rock face of the lower step is first sprayed with concrete with a thickness of 4 cm in time. A rock drill or anchor excavator is then used to install long rock bolts 9 at the bottom of the tunnel and inject M20 cement paste. The long lock bolt 9 of the tunnel is preferably a self-propelled lock bolt having a diameter of 32 mm and a length of 8 m. Install one self-propelled rock bolt every 1.0 m. Next, using a rock drill or an anchor excavator, a guide hole is drilled in the bottom of the tunnel, and grouting is performed through a grouting pipe 40 inserted into the guide hole. The depth of the guide holes is 3 m, one guide hole is drilled at intervals of 1.5 m in the circumferential direction, and one guide hole is drilled at intervals of 2.5 m in the longitudinal direction. Then use the steel arch assembly machine to install the first layer lower step primary lining so that the first layer lower step primary lining and the first layer upper step primary lining form a closed loop do. Before installing the upper step primary lining of the first layer, the third side wall steel arch 14, the fourth side wall steel arch 15, the first bottom steel arch 16, the fifth side wall steel arch 17 and the sixth side wall steel arch 18 are connected in order. Then, after installing the wire mesh, the wire mesh, the pipe-type rock bolt 10, etc. are welded and fixed to the primary upper step steel arch of the first layer respectively, and the concrete is sprayed again. This ensures that the total thickness of the first and second sprayed concrete of the lower step primary lining of the first layer is 27cm, ensuring that the whole is uniform, dense and without cavities behind. do.

Next, in step S6, the long lock bolt 8 on the side wall and the long lock bolt 9 on the bottom of the tunnel are installed in the lower step. A plurality of long rock bolts 8 are driven into the sidewalls on both sides of the lower step along the circumferential and longitudinal directions of the tunnel, and a plurality of tunnels are formed at the bottom of the tunnel along the circumferential and longitudinal directions of the tunnel. Drive the long lock bolt 9 at the bottom. The long lock bolt 8 on the side wall of the lower step and the long lock bolt 9 on the bottom of the tunnel are both self-propelled lock bolts with a diameter of 32 mm and a length of 8 m. Self-propelled rock bolts are installed, and one self-propelled rock bolt is installed at every 1.0m interval in the vertical direction.

Next, in step S7, a second layer of lower step primary lining is installed and concrete is sprayed to backfill the bottom of the tunnel. Here, a connecting steel frame connects the third side wall steel support 24, the first bottom steel support 25 and the fourth side wall steel support 26 before installing the second layer lower step primary lining. After the first layer of primary lining is initially stabilized, a steel arch assembler is used to install the second layer of lower step primary lining. The wire mesh is then installed, the wire mesh and the primary lower step steel arch of the second layer are welded and fixed, and the concrete is sprayed. This ensures that the bottom step primary lining of the second layer has a thickness of 25 cm after spraying concrete, ensuring that the whole is uniform, dense and without cavities behind. That is, the gap between the lower step primary lining of the second layer and the lower step primary lining of the first layer should be completely filled with concrete. Here, before the concrete is sprayed, after the lower step steel arches of the second layer of primary support are installed, joints are left on both sides of the externally exposed parts to protect them before the concrete is sprayed. That is, the third side wall steel arch 14 and the sixth side wall steel arch 18 are left with joints which are protected and then blasted with concrete. After the installation of the primary support for the second layer is completed, the slag in the cave backfills and compacts the bottom of the tunnel.

Next, in step S8, it is determined whether or not the tunnel has been excavated and penetrated. If it penetrates, only the following steps S9 to S12 are executed, and if it does not penetrate, steps S9 to S12 are executed for the previous construction area, and steps S1 to S7 are executed for the later construction area. Then, a short step is formed with 6m above in the vertical direction as one cycle, and the construction proceeds by quickly closing to a circular structure. The front construction area and the rear construction area are two adjacent construction areas, and for the sake of convenience, the front construction area is called the first construction area, and the rear construction area is the second construction area. call.

In step S9, the long lock bolt 8 on the side wall of the upper step and the long lock bolt 7 in the arch portion are installed. Along the tunnel's circumferential direction and longitudinal direction, a plurality of side wall long lock bolts 8 are installed on both side walls of the upper step, and along the tunnel's circumferential direction and longitudinal direction, a plurality of arched lengths are installed on the vault. A length lock bolt 7 is installed. The long rock bolts on the side walls of the upper steps use self-propelled rock bolts with a diameter of 32 mm and a length of 8 m. Install one self-propelled rock bolt at intervals of 1.0m. For the long lock bolts of the arch, resin lock bolts with a diameter of 25 mm and a length of 6 m are used, and one resin lock bolt is installed at intervals of 1.2 m in the circumferential direction, and the length is 1.2 m in the vertical direction. Install one resin rock bolt at intervals of .

To further improve the integrity of the fractured surrounding rock, a rock drill or anchor excavator is used to drill guide holes in the rock surrounding the arches and sidewalls for the entire tunnel, Grout is injected through a grout injection pipe 40 inserted into the guide hole. Here, the depth of the guide hole is 3 m, and reinforcement by grout injection is performed up to a range of 3 m along the excavation contour line. The guide holes are circumferentially spaced 1.5 m apart and longitudinally spaced 2.5 m apart.

Next, in step S10, the second layer of upper step primary lining is installed in the first construction area and the concrete is sprayed. In the second construction area, after excavating the face of the upper step by 15 to 20 m, and after the deformation of the primary lining of the first layer converges to 1/2 of the preliminary deformation amount, or the deformation is less than the preliminary deformation amount Install the second upper step primary lining when it is already stable but not 1/2 full. A preliminary deformation space for the first layer primary lining is formed between the second layer upper step primary lining and the first layer upper step primary lining, and the preliminary deformation amount of this preliminary deformation space is 30 cm. preferable. A second layer of primary lining is installed along the radial direction of the tunnel, the second layer of primary lining comprising a second upper step steel arch. The second upper step steel arch comprises a first sidewall steel support 21, a first top steel support 22 and a second sidewall steel support 23 connected in sequence. Before the second layer of primary lining, the first side wall steel support 21, the first top steel support 22 and the second side wall steel support 23 are connected in order, and then the steel arch assembling machine. to install the second upper step steel arch so that the second upper step steel arch and the second lower step steel arch form a closed ring. The wire mesh is then installed and fixed by welding the wire mesh and the primary lower step steel arch of the second layer before the concrete is sprayed. This ensures a thickness of 25 cm between the upper step primary linings of the second layer after spraying concrete, ensuring that the whole is uniform, dense and without cavities behind. That is, the gap between the upper step primary lining of the second layer and the upper step primary lining of the first layer should be completely filled with concrete.

Next, in step S11, reverse arch driving and reverse arch filling driving are performed. After the convergence deformation data of the area where the primary lining of the second layer in the first construction area is supported at a certain distance and the primary lining of the second layer is annularly closed is evaluated as stable, reverse Carry out filling and placing of the arch. First, an inverted arch template is installed, a double layer of steel bars is placed, and C35 concrete is used to cast the inverted arch. Basically, after the inverted arch has solidified, the inverted arch filling template is installed and C20 concrete is used to perform the filling and pouring.

Next, in step S12, the secondary lining is placed. A waterproofing layer is laid on the upper step primary lining of the second layer before placing the secondary lining. This waterproof layer comprises geotextile and waterproof panels. forming a pre-deformation space of the second layer primary lining between the waterproof layer and the second layer primary lining, or forming a pre-deformation space of the second layer primary lining between the secondary lining and the second layer primary lining; to form The waterproof layer is contained within the pre-deformation space of the primary lining of this second layer. The preliminary deformation amount of the preliminary deformation space of the primary lining of the second layer is smaller than the preliminary deformation amount of the preliminary deformation space of the primary lining of the first layer. 15 cm. Next, a secondary lining template is installed, a double layer of steel bars is placed, and the secondary lining is poured using C35 concrete so that the total thickness of the secondary lining is 60 cm. to After the secondary lining has been cast for a certain distance and the deformation of the secondary lining has stabilized, the conduit template for both sides of the groove is installed and the conduit is poured.

Although the present invention has been described in detail with preferred embodiments, the purpose thereof is to enable those skilled in the art to understand and implement the present invention. Of course, the protection scope of the present invention is not limited to the above embodiments and examples, and can be modified or improved within the spirit of the present invention, and both fall within the protection scope of the present invention.
Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is applied to construction of tunnels in high ground stress and soft rock. According to the present invention, a second layer of primary lining is installed between the first layer of primary lining and the waterproof layer, and the first layer of primary lining is placed between the first layer of primary lining and the second layer of primary lining. By forming a preliminary deformation space for the primary lining and forming a preliminary deformation space for the second layer primary lining between the second layer primary lining and the waterproof layer, the first layer primary lining and the second layer primary The lining can resist the pressure of the formation after excavation and unloading to the maximum extent, prevents the deformation that occurs in the inner circumference of the tunnel, and provides a preliminary deformation space for the primary lining of the first layer and a preliminary lining of the second layer. The deformation space can effectively release the deformation of the surrounding rock and reduce the force applied to the primary lining of the first layer and the primary lining of the second layer. Therefore, it is necessary to prevent the structural failure of the primary lining of the first layer and the primary lining of the second layer, and effectively solve the limitations of tunnel mechanization construction methods due to adverse geological conditions such as high ground stress and large deformation of soft rock. It is possible to greatly reduce the safety risk during tunnel construction, and to perform safe, high-speed, economical and rational construction.

Claims (10)

A support structure for a two-stage rapid closing tunnel with inverted arches, comprising:
along the circumference of the tunnel, with a vault at the top, an inverted arch at the bottom and side walls on both sides; a waterproof layer provided between a primary lining and said secondary lining of said waterproof layer comprising a geotextile and a waterproof panel;
said first layer of primary lining comprising a first layer of upper step primary lining and a first layer of lower step primary lining, said first layer of upper step primary lining comprising a first upper step steel arch; said first layer of lower step primary lining comprising a first lower step steel arch, said first upper step steel arch and said first lower step steel arch forming a head-to-tail closed ring; to form
Said support structure comprises a second layer of primary lining provided between said first layer of primary lining and said waterproof layer, said second layer of primary lining provided along a radial direction of the tunnel, said a second layer of primary lining comprising a second layer of upper step primary lining and a second layer of lower step primary lining, said second layer of upper step primary lining comprising a second upper step steel arch; Said second layer lower step primary lining comprises a second lower step steel arch, said second upper step steel arch and said second lower step steel arch being closed head-to-tail. A support structure for a two-stage high-velocity closed tunnel with inverted arches, characterized in that they form a ring. said first upper step steel arch comprising a first sidewall steel arch, a first top steel arch and a second sidewall steel arch connected in sequence; said first lower step steel arch; comprises a third sidewall steel arch, a fourth sidewall steel arch, a first bottom steel arch, a fifth sidewall steel arch, a sixth sidewall steel arch, connected in sequence; The end of the first end of the three side wall steel arches and said first side wall steel arch are connected, the second end of said third side wall steel arch extends downwards, and said fourth side wall A steel arch is connected to the side edge of the first end of the third side wall steel arch, and the end of the first end of the sixth side wall steel arch and the second side wall steel arch are connected. and the second end of the sixth side wall steel arch extends downward, and the fifth side wall steel arch is connected to the side of the first end of the sixth side wall steel arch. 2. The support structure of claim 1, wherein: The second upper step steel arch comprises a first sidewall steel support, a first top steel support, a second sidewall steel support connected in sequence, and the second lower step steel arch comprises in sequence a a connected third sidewall steel support, a first bottom steel support and a fourth sidewall steel support, said first sidewall steel support connecting with said third sidewall steel support and said second sidewall steel support 2. The support structure of claim 1, wherein a steel support connects with said fourth sidewall steel support. A pre-deformation space of the first layer primary lining is provided between the first layer primary lining and the second layer primary lining, and a second layer primary lining is provided between the second layer primary lining and the waterproof layer. A pre-deformation space for the primary lining of the layer is provided,
The pre-deformation amount of the pre-deformation space of the primary lining of the first layer is larger than the pre-deformation amount of the pre-deformation space of the primary lining of the second layer. Support structure as described. the first layer upper step primary lining further comprising an arch lock bolt unit;
wherein said arch lock bolt unit comprises a plurality of combined hollow lock bolts with exhaust devices, said multiple combined hollow lock bolts being arranged in said vault along the circumferential direction and the longitudinal direction of the tunnel. The support structure according to any one of claims 1 to 4. The support structure further comprises a reinforcing rockbolt unit,
The reinforcing rock bolt unit comprises a plurality of arch long rock bolts, a plurality of upper step sidewall long rock bolts, a plurality of lower step sidewall long rock bolts, and a plurality of tunnel bottom long rock bolts. ,
A plurality of long rock bolts of the arch portion are arranged in the vault along the circumferential direction and the longitudinal direction of the tunnel,
a plurality of elongated rock bolts of the upper step sidewall are arranged on both sides of the upper step sidewall along the circumferential and longitudinal directions of the tunnel;
a plurality of long rock bolts of the lower step sidewalls are arranged on both sides of the lower step sidewalls along the circumferential and longitudinal directions of the tunnel;
6. A support structure according to any one of claims 1 to 5, characterized in that a plurality of said tunnel bottom elongated rock bolts are arranged in the tunnel bottom along the circumferential and longitudinal directions of the tunnel. . A method of constructing a support structure for a two-stage fast-closing tunnel with an inverted arch, comprising:
a step of providing a front support for the upper step and a rock bolt for reinforcing the front support for the upper step;
excavating the upper step body of the tunnel;
providing the upper step primary lining of the first layer and spraying concrete;
excavating the lower step body of the tunnel;
providing a lower step primary lining of the first layer and spraying concrete;
providing an elongated rock bolt on the lower step sidewall and an elongated rock bolt on the bottom of the tunnel;
providing a second layer lower step primary lining and spraying concrete to backfill the bottom of the tunnel;
providing an upper step side wall elongated lock bolt and a vault elongated lock bolt;
providing a second layer of upper step primary lining and spraying concrete;
a step of casting the reverse arch and filling the reverse arch;
placing a secondary lining. In the construction method,
It is determined whether or not the tunnel has been excavated and penetrated, and if it has not been penetrated, the long rock bolt of the upper step side wall and the long rock bolt of the vault are driven in, and one after another along the longitudinal direction of the tunnel, providing pre-receiving supports of the upper step and pre-reinforcing rock bolts of the upper step; excavating the body of the upper step of the tunnel; providing the primary lining of the upper step of the first layer and spraying concrete; , excavating the body of the lower step of the tunnel, providing the primary lining of the lower step of the first layer and spraying concrete, and providing long rock bolts on the side walls of the lower step and long rock bolts at the bottom of the tunnel. In the process, the lower step of the second layer is provided with the primary lining, the concrete is sprayed, and the bottom of the tunnel is backfilled. The construction method according to claim 7, characterized by advancing. said upper step pre-receiving support comprising a plurality of pre-receiving injection canaliculi;
The construction method according to claim 7 or 8, wherein the plurality of pre-received injection small pipes are arranged along the circumferential direction and longitudinal direction of the tunnel. The anticipatory reinforcing rock bolt of the upper step has a plurality of longitudinal rock bolts, and the plurality of longitudinal rock bolts are arranged on the tunnel face of the tunnel upper step along the longitudinal direction of the tunnel. The construction method according to any one of claims 7 to 8, characterized in that:

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