Bias soft rock large-deformation tunnel supporting structure system and construction method thereof

Abstract

The invention relates to the field of railway tunnel construction, in particular to an unsymmetrical soft rock large-deformation tunnel supporting structure system and a construction method thereof. Comprising the steps of 1, establishing a primary support deformation database; 2, selecting different positions to reserve deformation characteristic values; thirdly, a primary support section is independently designed; fourthly, primary support construction is independently designed; step 5, performing section construction at the initial stage of the original design; sixthly, compensation grouting is conducted; and seventhly, secondary lining construction is conducted, the first step to the seventh step are repeated for multiple times, and the large deformation section of the soft rock is biased. The problem of repeated arch changing treatment of the soft rock bias tunnel can be prevented and reduced, the situation that when the tunnel primary support deforms, the whole section is synchronously enlarged, and secondary lining concrete in part of a section is seriously overconsumed is avoided, the construction efficiency is improved, and the cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of railway tunnel construction, and in particular to a biased soft rock large deformation tunnel support structure system and a construction method thereof. Background Art

[0002] During the construction of Jingzhai Tunnel of Yunnan-Mo Railway in Southwest China, due to extremely complex geological conditions, sensitive environment, fragile ecology, and the presence of a large number of soft surrounding rocks in the tunnel site area, the soft surrounding rocks have a wide distribution range, poor rock mass conditions, serious interlayer phenomenon, poor interlayer connection, easy softening when exposed to water, and obvious anisotropy and rheological properties. In addition, due to the great burial depth of the tunnel, extremely high initial geostress will be generated. Under the superposition of the above unfavorable factors, the tunnel will undergo large deformations of varying degrees, uncertainty in the deformation position and uneven deformation. The deformation of large deformations is much greater than the reserved deformation, resulting in initial support peeling, side wall bulging, and excessive deformation leading to serious limit intrusion. Under serious limit intrusion, the initial support must be replaced, which has a very adverse impact on the safety of construction personnel and equipment and construction progress.

[0003] During construction, due to the eccentric pressure and uneven distribution of the surrounding rock, the overall unevenness of the surrounding rock on the face, one side is good and the other side is bad, and the stability is different, which eventually causes the uneven deformation of the initial support and a large deformation of the primary support steel frame. At present, most of the measures to deal with the large deformation unevenness of weak eccentric tunnels are to select the maximum deformation as the reserved settlement and enlarge it as a whole on the original design section. The construction method is relatively conservative, the excavation section is expanded too much, and the deformation on the side with good surrounding rock stability is far less than the reserved deformation. The subsequent secondary lining construction has serious over-concrete, resulting in a waste of cost. When the secondary lining is constructed, the trolley is seriously biased and there are safety hazards. For tunnels, the construction efficiency is seriously affected. For this reason, a better support structure system and its construction method are needed to ensure construction progress, cost and safety. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a biased soft rock large deformation tunnel support structure system and a construction method thereof to solve the above problems, so that the deformation of the biased soft surrounding rock tunnel can be controlled, ensuring safety while having simple measures, low cost and high work efficiency.

[0005] The present invention provides a biased soft rock large deformation tunnel support structure system and a construction method thereof, which is characterized by comprising the following steps: Step 1: Statistically establish a database for the deformation of the initial support of the weak bias tunnel and analyze the convergence and settlement at different locations of the tunnel section; Step 2: Select reserved deformation characteristic values ​​at different locations of the tunnel according to the monitoring measurement data; Step 3: Design the initial support section separately according to the characteristic value of the reserved deformation; Step 4: During the tunnel excavation process, complete the tunnel excavation according to the individually designed initial support section and complete the subsequent initial support construction; Step 5: After the initial support of the separately designed section is completed, the deformation of the tunnel is continuously observed. When the tunnel section is close to the original designed tunnel section, the original designed initial support is immediately applied; Step 6: After the initial support of the original design is completed, grouting reinforcement is performed, and compensatory grouting is performed during each excavation cycle; Step seven: Tunnel secondary lining construction.

[0006] The database in step 1 includes vault settlement and side wall convergence.

[0007] The different positions of the tunnel in step 2 include the arch crown, the left arch rise point, the right arch rise point, the left arch waist point, the right arch waist point, the left arch foot point, and the right arch foot point. The reserved deformation characteristic value is the maximum cumulative value of the arch crown settlement and side wall convergence in the database.

[0008] The arch starting point is located at the side wall position 640-660 cm above the arch foot, the arch waist point is located at the side wall position 200-220 cm above the arch foot, and the arch apex is the intersection point of the tunnel centerline and the tunnel contour.

[0009] The step three designs the initial support section separately according to the characteristic value of the reserved deformation, and the design method is to design by the five-circle tangent method after point fitting: the three points of the arch top and the arch starting point are used to design the first circle; the arch starting points on both sides are connected with the arch waist points as the chords 1 and chord 2 of the second circle and the third circle, and the arch starting points are used as the tangent points of the first circle, the second circle and the third circle, and the second circle and the third circle are designed through chord 1, chord 2 and the arch starting points on both sides; the arch waist points on both sides are connected with the arch foot points as the chords 3 and chord 4 of the fourth circle and the fifth circle, and the arch waist points are used as the tangent points of the second circle and the third circle with the fourth circle and the fifth circle, and the fourth circle and the fifth circle are designed through chord 3, chord 4 and the arch waist points on both sides.

[0010] In the step 4, the tunnel excavation adopts the three-step method, and the length of each step is controlled at 5-6m. The initial support is to install anchor rods and steel frames, install locking anchor pipes, advance support, and close it with mesh and sprayed concrete.

[0011] The anchor rod adopts Ф22 resin anchor rod, the anchor agent adopts Ф28 quick anchor agent, and the anchor rod spacing is 1m×1m in ring×vertical; the steel frame includes steel arch frame and grid arch frame, and the steel frame spacing is controlled between 0.5-0.8m; the locking foot anchor pipe adopts Ф42 seamless steel pipe, 4.5m long, and the driving angle is controlled between 20° and 30°. The locking foot anchor pipe and the steel frame are connected by L-shaped reinforcement. The locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa; the advanced support includes an advanced small guide tube and an advanced pipe shed, and the driving angle of the advanced support is controlled at 10° to 20°. The advanced support grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa; the shotcrete is constructed in pieces and layers by a wet spraying manipulator.

[0012] In step five, the original designed initial support is implemented including steel frame, locking feet, hanging nets, and shotcrete sealing.

[0013] The steel frame includes a steel arch frame and a grid arch frame, and the spacing between the steel frames is controlled between 0.5-0.8m; the locking foot anchor pipe is made of Ф42 seamless steel pipe, 4.5m long, and the driving angle is controlled between 20° and 30°. The locking foot anchor pipe and the steel frame are connected by L-shaped reinforcement; the locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa.

[0014] In the step six, the compensatory grouting adopts the arch wall radial grouting method, the grouting drilling diameter is Ф50mm, the depth is 3m, the grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.5-2Mpa.

[0015] The present invention has the advantages that: 1. The present invention mainly solves the problem of uneven deformation of initial support of weak biased railway tunnels and the problem of cracking and limit intrusion of initial support caused by large deformation. By selecting characteristic values ​​of deformation at different positions to design sections separately + compensatory grouting and other measures, the uneven large deformation of weak biased tunnels is processed to avoid arch replacement caused by initial support limit intrusion. The cost is low, the strength of the initial support is improved, the construction safety is ensured, the cost is saved, the arch replacement is avoided, and the construction period is shortened.

[0016] 2. The biased soft rock large deformation tunnel support structure system and its construction method provided by the present invention can be directly applied to the actual construction of soft biased tunnels, which can avoid the situation in traditional construction where the deformation amount is less than the reserved deformation amount, resulting in excessive consumption of secondary lining concrete and waste of costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flowchart of the method of the present invention.

[0018] Figure 2 It is a schematic diagram of the biased soft rock large deformation tunnel support structure system of the present invention.

[0019] Figure 3 It is a schematic diagram of the cross section of the five-circle tangent design of the present invention.

[0020] Figure 4 It is a schematic diagram of deformation data collection points for the initial branch deformation of the biased soft rock large deformation tunnel of the present invention.

[0021] Figure 5 It is a schematic diagram of the initial support surface deformation before construction of the biased soft rock large deformation tunnel support structure system construction method of the present invention.

[0022] Figure 6 It is a schematic diagram of the deformation of the initial support surface after the construction method of the biased soft rock large deformation tunnel support structure system of the present invention is completed.

[0023] In the figure: 1-separately designed initial support section, 2-five-circle tangent arch frame, 3-locking anchor pipe, 4-resin anchor rod, 5-advance support, 6-original designed initial support, 7-inverted arch, 8-inverted arch initial support, 9-secondary lining. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figures 1 to 6 As shown, this embodiment provides a biased soft rock large deformation tunnel support structure system and a construction method thereof, which includes the following steps when soft biased surrounding rock appears during tunnel excavation: Step 1: Statistically analyze the initial support deformation of soft rock to establish an initial support deformation database; the initial support deformation database includes the arch settlement and side wall convergence.

[0027] Step 2: According to the monitoring and measurement data, select the reserved deformation characteristic values ​​at different positions of the tunnel; the different positions include the arch crown, the left arch point, the right arch point, the left arch waist point, the right arch waist point, the left arch foot point, and the right arch foot point. The specific situation is as attached Figure 2The arch point is located at the side wall position 660cm above the arch foot; the arch waist point is located at the side wall position 200cm above the arch foot; the arch vertex is the intersection of the tunnel centerline and the tunnel contour; the reserved deformation characteristic value is the maximum cumulative value of the arch crown settlement and side wall convergence in the database.

[0028] Step three, design the initial support section separately according to the characteristic value of the reserved deformation; the design method is to design by the five-circle tangent method after point fitting: the first circle is designed by the three points of the arch top point and the arch starting point; the arch starting points on both sides are connected with the arch waist point as the chord 1 and chord 2 of the second circle and the third circle, the arch starting point is used as the tangent point of the first circle with the second circle and the third circle, and the second circle and the third circle are designed by chord 1, chord 2 and the arch starting points on both sides; the arch waist points on both sides are connected with the arch foot points as the chord 3 and chord 4 of the fourth circle and the fifth circle, the arch waist point is used as the tangent point of the second circle and the third circle with the fourth circle and the fifth circle, and the fourth circle and the fifth circle are designed by chord 3, chord 4 and the arch waist points on both sides.

[0029] Step 4: During the tunnel excavation process, the tunnel excavation is completed according to the individually designed initial support section, and the subsequent initial support construction is completed; in the step 4, the tunnel excavation is excavated using a three-step method, and the length of each step is controlled at 5m. The initial support is to construct anchor rods, steel frames, set up locking anchor pipes, advance support, and hang nets and spray concrete to close. The anchor rods use Ф22 resin anchor rods, and the anchoring agent uses Ф28 fast anchoring agent. The anchor rod spacing is 1m×1m in ring × vertical. The steel frame includes a steel arch frame and a grid arch frame. The spacing between the steel frames is controlled between 0.5m. The locking foot anchor pipe uses a Ф42 seamless steel pipe, 4.5m long, and the setting angle is controlled at 20°. The locking foot anchor pipe and the steel frame are connected by L-shaped bars. The locking foot anchor pipe grouting uses double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5Mpa. The advance support includes an advance small guide tube and an advance pipe shed. The angle of the advanced support is controlled at 10°. The advanced support grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5Mpa. The sprayed concrete is constructed in sections and layers using a wet spraying manipulator.

[0030] Step 5. After the initial support of the individually designed section is completed, the deformation of the tunnel is continuously observed. When the tunnel section is close to the original designed tunnel section, the original designed initial support is immediately applied; the original designed parameters are adopted.

[0031] Step six, after completing the original designed initial support, grouting reinforcement is carried out, and compensatory grouting is carried out during each excavation cycle; the compensatory grouting adopts the method of radial grouting of the arch wall, the grouting drilling diameter is Ф50mm, the depth is 3m, the grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.5Mpa.

[0032] Step seven: Secondary lining construction of the tunnel; the initial support is closed in time, the end of the invert is controlled at 35m from the excavation surface, and the end of the secondary lining is controlled at 60m from the excavation surface.

[0033] This example can well control the uneven deformation of the weak biased tunnel, and avoid the situation in which the deformation in traditional construction is less than the reserved deformation, resulting in excessive consumption of secondary lining concrete and waste of costs. It has strong adaptability and scalability.

[0034] Example 2

[0035] The steps of the biased soft rock large deformation tunnel support structure system and its construction method described in this embodiment are the same as those in Embodiment 1, except that: In step 2, the arch starting point is located at the side wall position 425 cm above the arch foot; the arch waist point is located at the side wall position 210 cm above the arch foot; In step four, the length of each step is controlled at 5.5m; the spacing between steel frames is controlled at 0.6m; the locking foot anchor pipe adopts Ф42 seamless steel pipe, 4.5m long, and the setting angle is controlled at 25°. The locking foot anchor pipe and the steel frame are connected with L-shaped bars. The locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.0Mpa. The advance support includes an advance small guide tube and an advance pipe shed. The setting angle of the advance support is controlled at 15°. The advance support grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.0Mpa; In step six, the grouting pressure is controlled at 1.75 MPa.

[0036] Example 3

[0037] The steps of the biased soft rock large deformation tunnel support structure system and its construction method described in this embodiment are the same as those in Embodiment 1, except that: In step 2, the arch starting point is located at the side wall position 440 cm above the arch foot; the arch waist point is located at the side wall position 220 cm above the arch foot; In step four, the length of each step is controlled at 6m; the spacing between steel frames is controlled within 0.8m; the locking foot anchor pipe adopts Ф42 seamless steel pipe, 4.5m long, and the setting angle is controlled at 30°. The locking foot anchor pipe and the steel frame are connected with L-shaped bars. The locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.5Mpa. The advance support includes an advance small guide tube and an advance pipe shed. The setting angle of the advance support is controlled at 20°. The advance support grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.5Mpa; In step six, the grouting pressure is controlled at 2Mpa.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Biased soft rock large deformation tunnel support structure system and construction method thereof, characterized in that: It includes the following steps: Step 1: Statistically establish a database for the initial deformation of the biased soft rock large deformation tunnel, and analyze the convergence and settlement at different positions of the tunnel section; Step 2: Select reserved deformation characteristic values ​​at different locations of the tunnel according to the monitoring measurement data; Step 3: Design the initial support section separately according to the characteristic value of the reserved deformation; Step 4: During the tunnel excavation process, complete the tunnel excavation according to the individually designed initial support section and complete the subsequent initial support construction; Step 5: After the initial support of the separately designed section is completed, the deformation of the tunnel is continuously observed. When the tunnel section is close to the original designed tunnel section, the original designed initial support is immediately applied; Step 6: After the initial support of the original design is completed, grouting reinforcement is performed, and compensatory grouting is performed during each excavation cycle; Step seven: Tunnel secondary lining construction.

2. The biased soft rock large deformation tunnel support structure system and construction method thereof according to claim 1 is characterized in that: The database in step 1 includes vault settlement and side wall convergence.

3. The biased soft rock large deformation tunnel support structure system and construction method thereof according to claim 1 is characterized in that: The different positions of the tunnel in step 2 include the arch crown, the left arch rise point, the right arch rise point, the left arch waist point, the right arch waist point, the left arch foot point, and the right arch foot point. The reserved deformation characteristic value is the maximum cumulative value of the arch crown settlement and side wall convergence in the database.

4. The biased soft rock large deformation tunnel support structure system and construction method thereof according to claim 3 is characterized in that: The arch starting point is located at the side wall position 640-660 cm above the arch foot, the arch waist point is located at the side wall position 200-220 cm above the arch foot, and the arch apex is the intersection point of the tunnel centerline and the tunnel contour.

5. The biased soft rock large deformation tunnel support structure system and construction method according to claim 1 is characterized in that: The step three designs the initial support section separately according to the characteristic value of the reserved deformation, and the design method is to design by the five-circle tangent method after point fitting: the three points of the arch top and the arch starting point are used to design the first circle; the arch starting points on both sides are connected with the arch waist points as the chords 1 and chord 2 of the second circle and the third circle, and the arch starting points are used as the tangent points of the first circle, the second circle and the third circle, and the second circle and the third circle are designed through chord 1, chord 2 and the arch starting points on both sides; the arch waist points on both sides are connected with the arch foot points as the chords 3 and chord 4 of the fourth circle and the fifth circle, and the arch waist points are used as the tangent points of the second circle and the third circle with the fourth circle and the fifth circle, and the fourth circle and the fifth circle are designed through chord 3, chord 4 and the arch waist points on both sides.

6. The biased soft rock large deformation tunnel support structure system and construction method according to claim 1 are characterized by: The tunnel excavation in step 4 is carried out using a three-step excavation method, with each step length controlled at 5-6m. The initial support is the installation of anchor rods, steel frames, the installation of locking anchor pipes, advance support, and sealing with mesh and sprayed concrete.

7. The biased soft rock large deformation tunnel support structure system and construction method according to claim 6 are characterized by: The anchor rod adopts Ф22 resin anchor rod, the anchor agent adopts Ф28 quick anchor agent, and the anchor rod spacing is 1m×1m in ring×vertical; the steel frame includes steel arch frame and grid arch frame, and the steel frame spacing is controlled between 0.5-0.8m; the locking foot anchor pipe adopts Ф42 seamless steel pipe, 4.5m long, and the driving angle is controlled between 20° and 30°. The locking foot anchor pipe and the steel frame are connected by L-shaped reinforcement. The locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa; the advanced support includes an advanced small guide tube and an advanced pipe shed, and the driving angle of the advanced support is controlled at 10° to 20°. The advanced support grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa; the shotcrete is constructed in pieces and layers by a wet spraying manipulator.

8. The biased soft rock large deformation tunnel support structure system and construction method according to claim 1 are characterized by: In step five, the original designed initial support is implemented including steel frame, locking feet, hanging nets, and shotcrete sealing.

9. The biased soft rock large deformation tunnel support structure system and construction method according to claim 8, characterized in that: The steel frame includes a steel arch frame and a grid arch frame, and the spacing between the steel frames is controlled between 0.5-0.8m; the locking foot anchor pipe is made of Ф42 seamless steel pipe, 4.5m long, and the driving angle is controlled between 20° and 30°. The locking foot anchor pipe and the steel frame are connected by L-shaped reinforcement; the locking foot anchor pipe grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 0.5-1.5Mpa.

10. The biased soft rock large deformation tunnel support structure system and construction method according to claim 1, characterized in that: In the step six, the compensatory grouting adopts the arch wall radial grouting method, the grouting drilling diameter is Ф50mm, the depth is 3m, the grouting adopts double liquid slurry, cement slurry: water glass = 1:1, and the grouting pressure is controlled at 1.5-2Mpa.

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