A construction method for widening one side of an existing tunnel

Abstract

The present invention relates to the technical field of tunnel construction, and provides a construction method for the expansion and reconstruction of a single-sided widening of an existing tunnel. The starting section of the existing tunnel for expansion and reconstruction is determined according to lining detection information and surrounding rock survey information. The starting section is located in the middle section of the existing tunnel. The starting section is expanded and reconstructed, and then the expanded and reconstructed starting section is used to perform advance support on adjacent tunnel sections in the first direction, and the expanded and reconstructed starting section is used to perform advance support on adjacent tunnel sections in the second direction. The remaining tunnel sections in the first direction are expanded and the remaining tunnel sections in the second direction are expanded to complete the expansion and reconstruction of the existing tunnel. The present application sets the starting section in the middle section to solve the problem of limited construction surface, and can carry out synchronous construction from both ends of the starting section. It can increase multiple construction surfaces according to the construction period requirements, and can also reduce the disturbance of the surrounding rock, reduce the engineering risk, and shorten the construction period.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, in particular to a reconstruction and expansion construction method for widening one side of an existing tunnel. Background Art

[0002] With economic development, the construction of transportation network is becoming more perfect. The road traffic volume in economically developed areas cannot meet the needs of economic development. Therefore, highway reconstruction and expansion has been launched. In highway reconstruction and expansion, the most difficult part is the reconstruction and expansion of tunnels. Tunnel reconstruction and expansion plans are roughly divided into two plans: in-situ excavation and separate construction. Limited by the rapid development of the block economy, the red line range of the reconstruction and expansion project is strictly controlled. In addition, in order to reduce the mutual influence between the left and right lines of the tunnel, the single-side widening plan of the tunnel is often adopted.

[0003] In the existing technology, the construction plan of tunnel unilateral widening requires pre-reinforcement of the surrounding rock, so the starting working surface is usually selected at the tunnel entrance, and the surrounding rock stability is increased by the advanced long pipe shed before the expansion and reconstruction. However, this practice limits the construction surface of the tunnel expansion and reconstruction, and it is impossible to speed up the tunnel construction by increasing the construction operation surface. Once the project schedule is tight, it will not be able to meet the requirements; in addition, the tunnel entrance section is generally a section with poor geology and shallow burial depth, so the starting working surface is selected at the tunnel entrance for construction. The risk is relatively high. Therefore, this expansion and reconstruction plan that sets the starting working surface at the tunnel entrance is not the best choice.

[0004] In addition, the above scheme still follows the principle of "New Austrian Tunneling Method" during the renovation and expansion process, that is, the steel frame combined with anchor spraying support is adopted. This method has the problem of insufficient rigidity of the support structure, and the surrounding rock allows a large deformation; secondly, the entire support process relies heavily on manual labor and has a long construction period; thirdly, even after the support structure is completed, since it takes a certain amount of time for the sprayed concrete to reach the design strength requirements, it is impossible to form an effective protection system in the first time, and the timeliness is poor, resulting in a long exposure time of the surrounding rock and large disturbance, which brings higher construction risks.

[0005] In view of this, it is necessary to propose a reconstruction and expansion construction method for widening one side of an existing tunnel to solve or at least alleviate the above-mentioned defects. Summary of the invention

[0006] The main purpose of the present invention is to provide a construction method for widening one side of an existing tunnel, so as to solve the technical problems in the prior art of setting the starting working surface of the expansion and reconstruction at the tunnel entrance, resulting in limited construction surface and greater construction risks.

[0007] To achieve the above object, the present invention provides a construction method for widening one side of an existing tunnel, comprising the following steps:

[0008] S1, obtaining lining detection information and surrounding rock survey information of an existing tunnel, and determining a starting section for renovation and expansion of the existing tunnel according to the lining detection information and the surrounding rock survey information; wherein the starting section is located in the middle section of the existing tunnel;

[0009] S2, reconstructing and expanding the starting section, and then using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a first direction, and using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a second direction; wherein the first direction and the second direction are opposite;

[0010] S3, reconstructing and expanding the remaining tunnel sections in the first direction and reconstructing and expanding the remaining tunnel sections in the second direction to complete the reconstruction and expansion of the built tunnel.

[0011] Preferably, the reconstruction and expansion of the starting section in step S2 specifically includes the following steps:

[0012] S21, first remove the initial support of the non-widened area and expand the excavation to the designed contour line, and retain the initial support of the widened area as a temporary support structure, and then spray concrete on the surrounding rock wall of the non-widened area; wherein the arch wall area of ​​the starting section includes a non-widened area and multiple widened areas that are connected in sequence along the tunnel circumference;

[0013] S22, installing a first prefabricated lining structure matching the non-widened area; wherein one end of the first prefabricated lining structure overlaps the surrounding rock of the widened area, and the other end overlaps the tunnel arch foot; the first prefabricated lining structure has a first reserved hole for a first system anchor to penetrate; and the first system anchor is driven through the first reserved hole to fix the first prefabricated lining structure;

[0014] S23, remove the initial support of the i-th widening area and expand the excavation to the design contour line, and retain the initial support of the remaining widening area as a temporary support structure, and then spray concrete on the surrounding rock wall of the i-th widening area;

[0015] S24, installing a second prefabricated lining structure matching the i-th widening area; wherein, when the i-th widening area is the first widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the first prefabricated lining structure, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and entering step S251; i≥1, i is a positive integer;

[0016] When i is greater than 1 and the i-th widening area is not the last widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the second prefabricated lining structure of the i-1-th widening area, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and the process goes to step S251;

[0017] When the i-th widening area is the last widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the second prefabricated lining structure of the i-1-th widening area, and the other end is overlapped with the tunnel arch foot, and the process proceeds to step S252;

[0018] S251, drilling a second system anchor through a second reserved hole to fix the second prefabricated lining structure of the i-th widened area, assigning i+1 to i, and then proceeding to step S23;

[0019] S252, installing a second system anchor through a second reserved hole to fix the second prefabricated lining structure of the i-th widened area; dismantling the original invert structure and expanding the excavation to the designed contour line, and then constructing a prefabricated invert; wherein one end of the prefabricated invert is connected to the first prefabricated lining structure, and the other end is connected to the second prefabricated lining structure of the i-th widened area.

[0020] Preferably, the reconstruction and expansion of the remaining tunnel sections in the first direction in step S3 specifically includes the following steps:

[0021] S31, when the surrounding rock grade of the remaining tunnel section is greater than or equal to grade 4, the first area and the second area of ​​the remaining tunnel section with a preset cycle footage are first rebuilt and expanded along the first direction; wherein the arch wall area of ​​each remaining tunnel section is divided into a first area, a second area located in the widening area, a third area, and a fourth area in sequence along the tunnel circumference;

[0022] S32, reconstructing and expanding a third area of ​​the remaining tunnel section of the preset cycle footage along the first direction;

[0023] S33, reconstructing and expanding a fourth area of ​​the remaining tunnel sections of the preset cycle footage along the first direction;

[0024] S34, dismantling the original invert structure corresponding to the preset cycle footage, expanding the excavation to the designed contour line, and then constructing the prefabricated invert corresponding to the preset cycle footage;

[0025] Repeat steps S31 to S34 until the reconstruction and expansion of the remaining tunnel sections in the first direction are completed.

[0026] Preferably, in step S31, the first area and the second area of ​​the remaining tunnel section of the preset cycle footage are first rebuilt and expanded along the first direction, specifically comprising the following steps:

[0027] S311, first remove the initial support of the first area of ​​the current remaining tunnel section and expand the excavation to the designed contour line, then remove the initial support of the second area and expand the excavation to the designed contour line, and retain the initial support of the third area and the fourth area as temporary support structures;

[0028] S312, spraying concrete on the surrounding rock wall surfaces of the first area and the second area, installing a first prefabricated lining structure matching the first area and a second prefabricated lining structure matching the second area; then drilling first system anchor rods through the first reserved holes to fix the first prefabricated lining structure, and drilling second system anchor rods through the second reserved holes to fix the second prefabricated lining structure;

[0029] S313, using the first prefabricated lining structure and the second prefabricated lining structure to lay advance support to reinforce the first area and the second area of ​​the next remaining tunnel section;

[0030] S314, repeating steps S311 to S313 to complete the reconstruction and expansion of the first area and the second area of ​​the remaining tunnel sections of the preset cycle footage.

[0031] Preferably, the step S32 specifically includes the steps of:

[0032] S321, removing the initial support of the third area of ​​the current remaining tunnel section and expanding the excavation to the design contour line, spraying concrete on the inner wall of the surrounding rock of the third area, installing a second prefabricated lining structure matching the third area, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure;

[0033] S322, using the second prefabricated lining structure to set up advance support to reinforce the third area of ​​the next remaining tunnel section;

[0034] S323, repeating steps S321-S322 to complete the reconstruction and expansion of the third area of ​​the remaining tunnel sections of the preset cycle footage.

[0035] Preferably, the step S33 specifically includes the steps of:

[0036] S331, removing the initial support of the fourth area of ​​the current remaining tunnel section and expanding the tunnel to the design contour line of the fourth area, spraying concrete on the inner wall of the surrounding rock of the fourth area, installing a second prefabricated lining structure matching the fourth area, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure;

[0037] S332, using the second prefabricated lining structure to set up advance support to reinforce the fourth area of ​​the next remaining tunnel section;

[0038] S333, repeating steps S331-S332 to complete the reconstruction and expansion of the fourth area of ​​the remaining tunnel sections of the preset cycle footage.

[0039] Preferably, the first prefabricated lining structure includes a first steel box, the inner wall of the first steel box is provided with a first grouting hole, and ultra-high performance concrete is filled in the first steel box through the first grouting hole to form a first grouting structure layer; the inner wall and the outer wall of the first steel box are both provided with a first reserved hole for the first system anchor rod to pass through, and the first reserved hole on the inner wall of the first steel box and the first reserved hole on the outer wall of the first steel box are arranged in a one-to-one correspondence; wherein, the first system anchor rod includes a first anchoring end and a first locking end, the first anchoring end is anchored into the surrounding rock after passing through the first reserved hole, and the first locking end is connected to the inner wall of the first steel box.

[0040] Preferably, the second prefabricated lining structure includes a second steel box, the inner wall of the second steel box is provided with a second grouting hole, and ultra-high performance concrete is filled in the second steel box through the second grouting hole to form a second grouting structure layer; the inner wall and the outer wall of the second steel box are both provided with a second reserved hole for the second system anchor rod to pass through, and the second reserved holes on the inner wall of the second steel box and the second reserved holes on the outer wall of the second steel box are arranged in a one-to-one correspondence; wherein, the second system anchor rod includes a second anchoring end and a second locking end, the second anchoring end is anchored into the surrounding rock after passing through the second reserved hole, and the second locking end is connected to the inner wall of the second steel box.

[0041] Preferably, the step S23 of spraying concrete on the surrounding rock wall surface of the i-th widening area specifically includes the steps of: spraying 8 cm thick C25 concrete on the surrounding rock wall surface of the i-th widening area.

[0042] Preferably, the length of the starting section is set between 2 and 5 m, and the length of each remaining tunnel section is set between 2 and 6 m.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a construction method for the expansion and reconstruction of a single-side widening of an existing tunnel. The starting section of the expansion and reconstruction of the existing tunnel is determined according to lining detection information and surrounding rock survey information. The starting section is located in the middle section of the existing tunnel. The starting section is expanded and reconstructed. The expanded and reconstructed starting section is used to perform advance support on adjacent tunnel sections in the first direction, and the expanded and reconstructed starting section is used to perform advance support on adjacent tunnel sections in the second direction. The remaining tunnel sections in the first direction are expanded and the remaining tunnel sections in the second direction are expanded to complete the expansion and reconstruction of the existing tunnel. The present application sets the starting section in the middle section to solve the problem of limited construction surface, and can carry out synchronous construction from both ends of the starting section. Multiple construction surfaces can be added according to the construction period requirements, and the surrounding rock disturbance can be reduced, the engineering risk can be reduced, and the construction period can be shortened.

[0045] Secondly, during the process of removing the initial support and expanding the excavation, the initial support of the remaining area is retained as a temporary supporting structure, one end of the first prefabricated lining structure is overlapped on the surrounding rock, and one end of the second prefabricated lining in some areas is overlapped on the surrounding rock, so that the first prefabricated lining structure and / or the second prefabricated lining structure and the remaining original lining structure can temporarily form an arch structure to ensure structural stability; by gradually dismantling and expanding each widened area, and then installing the prefabricated lining structure, the construction is orderly and safe; the use of prefabricated lining structures instead of traditional on-site casting greatly improves construction efficiency and shortens construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0047] Figure 1 is a schematic diagram of a flow chart in one embodiment of the present invention;

[0048] Figure 2 It is a flowchart of the specific steps of modifying and expanding the starting section in step S2 in one embodiment of the present invention;

[0049] Figure 3 A schematic diagram of a tunnel reconstruction and expansion area in an embodiment of the present invention;

[0050] Figure 4 It is a schematic diagram of the structure of a tunnel after reconstruction and expansion in one embodiment of the present invention;

[0051] Figure 5 It is a schematic diagram of the annular connection of the second steel boxes in the second area, the third area and the fourth area in one embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram of the longitudinal docking of the first steel box in the first area in one embodiment of the present invention.

[0053] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

[0054] Description of Figure Numbers:

[0055] 10. Design contour line; 20. Original tunnel excavation contour line; 310. First area; 320. Second area; 330. Third area; 340. Fourth area; 410. First prefabricated lining structure; 420. Second prefabricated lining structure; 50. Prefabricated invert; 60. First steel box; 610. First groove; 620. First protrusion; 70. Second steel box; 710. Second groove; 720. Second protrusion. DETAILED DESCRIPTION

[0056] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0059] In addition, the descriptions of "right part", "middle part" and the like in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "right part" and "middle part" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0060] Please refer to the attached Figures 1 to 6 In one embodiment of the present invention, a construction method for widening one side of an existing tunnel comprises the following steps:

[0061] S1, obtaining lining detection information and surrounding rock survey information of an existing tunnel, and determining a starting section for renovation and expansion of the existing tunnel according to the lining detection information and the surrounding rock survey information; wherein the starting section is located in the middle section of the existing tunnel;

[0062] S2, reconstructing and expanding the starting section, and then using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a first direction, and using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a second direction; wherein the first direction and the second direction are opposite, and both the first direction and the second direction extend along the extension direction of the tunnel;

[0063] S3, reconstruct and expand the remaining tunnel sections in the first direction and reconstruct and expand the remaining tunnel sections in the second direction to complete the reconstruction and expansion of the built tunnel. That is, one end face of the reconstructed and expanded starting section is used as a construction surface to reconstruct and expand the remaining tunnel sections in the first direction, and the other end face of the reconstructed and expanded starting section is used to reconstruct and expand the remaining tunnel sections in the second direction. As a preferred example, the length of the starting section is set between 2 and 5 meters, the number of the remaining tunnel sections is multiple, and the length of each remaining tunnel section is set between 2 and 6 meters.

[0064] It is understandable that the risk of tunnel lining demolition is high. Before demolition, the integrity and stability of the original lining should be checked. Monitoring points can be arranged in the built tunnel, or ultrasonic non-destructive testing methods can be used for testing. When the test results show that the lining has defects, such as hollowing, water seepage, etc., the defects should be analyzed and reinforcement measures (such as grouting reinforcement, etc.) should be considered during the demolition process. When the test results show that the lining at the demolition point is normal, demolition work can be carried out; surrounding rock survey information can be obtained by using methods such as sonic method and electric detection to survey the surrounding rock around the tunnel lining, so as to obtain surrounding rock geological information, such as surrounding rock grade, to provide geological basis for the renovation and expansion project. Generally speaking, surrounding rock grades greater than or equal to grade four are considered to be poor surrounding rock.

[0065] Unlike the prior art, the starting section of the renovation and expansion plan of this application is not selected at the tunnel entrance. Instead, based on the acquired lining inspection information and surrounding rock survey information, the middle section with better integrity and stability of the original lining is preferentially selected. That is, the starting section is located in the middle section of the existing tunnel. The tunnel is divided into the entrance section (entrance section), the middle section, and the exit section along the extension direction. Setting the starting section at this position can solve the problem of limited construction surface, and simultaneous construction can be carried out from both ends of the starting section. Multiple construction surfaces can be added according to the construction period requirements.

[0066] Preferably, the starting section has a complete lining and a surrounding rock grade less than Grade 4. If the surrounding rock grade is greater than or equal to Grade 4, after the secondary lining is removed, radial grouting is performed on the surrounding rock through the original tunnel initial support to improve the surrounding rock stability, and then the removal of the initial support and excavation work are started.

[0067] The starting section after reconstruction and expansion is used to implement advance support for the adjacent tunnel sections in the first direction (for example, from the starting section to the tunnel exit). The advance support can be that before the construction of the adjacent tunnel sections, the starting section is used to inject grout into the stratum in front of the construction surface, and steel pipes, steel plates, anchor rods and other measures are driven in to form an arched continuum on the cross-section of the adjacent tunnel section to reinforce the stratum in front. Similarly, the starting section after reconstruction and expansion is also used to implement advance support for the adjacent tunnel sections in the second direction (for example, from the starting section to the tunnel entrance). The first direction and the second direction are opposite to ensure construction safety during the entire reconstruction and expansion process.

[0068] After completing the reconstruction and expansion and advance support of the starting section, the remaining tunnel sections in the first direction can continue to be reconstructed and expanded, and the remaining tunnel sections in the second direction can also be reconstructed and expanded simultaneously, which can effectively shorten the reconstruction and expansion period.

[0069] As a preferred implementation, the reconstruction and expansion of the starting section in step S2 specifically includes the following steps:

[0070] S21, first remove the initial support of the non-widened area and expand the excavation to the design contour line 10, and retain the initial support of the widened area as a temporary support structure, and then spray concrete on the surrounding rock wall of the non-widened area; wherein the arch wall area of ​​the starting section includes a non-widened area and multiple widened areas that are connected in sequence along the tunnel circumference;

[0071] S22, installing a first prefabricated lining structure 410 matching the non-widened area; wherein one end of the first prefabricated lining structure 410 overlaps the surrounding rock of the widened area, and the other end overlaps the tunnel arch foot; the first prefabricated lining structure 410 has a first reserved hole for a first system anchor to penetrate; and the first system anchor is driven through the first reserved hole to fix the first prefabricated lining structure 410;

[0072] S23, remove the initial support of the i-th widening area and expand the excavation to the designed contour line 10, and retain the initial support of the remaining widening area as a temporary supporting structure, and then spray concrete on the surrounding rock wall of the i-th widening area; further, the spraying of concrete on the surrounding rock wall of the i-th widening area in step S23 specifically includes the steps of: spraying 8 cm thick C25 concrete on the surrounding rock wall of the i-th widening area.

[0073] S24, installing a second prefabricated lining structure 420 matching the i-th widening area; wherein, when the i-th widening area is the first widening area, one end of the second prefabricated lining structure 420 of the i-th widening area is connected to the first prefabricated lining structure 410, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and proceeding to step S251; i≥1, i is a positive integer;

[0074] When i is greater than 1 and the i-th widening area is not the last widening area, one end of the second prefabricated lining structure 420 of the i-th widening area is connected to the second prefabricated lining structure 420 of the i-1-th widening area, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and the process goes to step S251;

[0075] When the i-th widening area is the last widening area, one end of the second prefabricated lining structure 420 of the i-th widening area is connected to the second prefabricated lining structure 420 of the i-1-th widening area, and the other end is overlapped with the tunnel arch foot, and the process proceeds to step S252;

[0076] S251, drilling a second system anchor through a second reserved hole to fix the second prefabricated lining structure 420 of the i-th widened area, assigning i+1 to i, and then proceeding to step S23;

[0077] S252, installing a second system anchor through a second reserved hole to fix the second prefabricated lining structure 420 of the i-th widened area; dismantling the original inverted arch structure and expanding the excavation to the designed contour line 10, and then constructing a prefabricated inverted arch 50; wherein one end of the prefabricated inverted arch 50 is connected to the first prefabricated lining structure 410, and the other end is connected to the second prefabricated lining structure 420 of the i-th widened area.

[0078] Specifically, Figure 3 As shown, the initial support of the non-widening area is first removed, and then the excavation is carried out according to the design contour line 10 (i.e., the excavation contour line of the tunnel after the expansion) to form a larger tunnel space. Then, according to the size and shape of the non-widening area, a matching first prefabricated lining structure 410 is installed, one end of the first prefabricated lining structure 410 overlaps the surrounding rock of the widening area, and the other end overlaps the tunnel arch foot. The first system anchor rod is set through the reserved first reserved hole to fix the first prefabricated lining structure 410.

[0079] It should be noted that the boundary between the non-widening area and the widening area can be determined in advance according to the design requirements. Preferably, the widening of the built tunnel is usually realized on the outside, for example, the boundary between the non-widening area and the widening area is the center line of the tunnel;

[0080] Next, the first widened area near the non-widened area is rebuilt and expanded by removing the corresponding initial support and excavating according to the design contour line 10, and spraying concrete on the surrounding rock wall after the excavation. According to the size and shape of the widened area, a matching second prefabricated lining structure 420 is installed, and the second prefabricated lining structure 420 is preferably an arc structure.

[0081] Among them, for the first widening area (the widening area connected to the non-widening area), one end of its prefabricated lining structure is connected to the first prefabricated lining structure 410, and the other end is overlapped with the surrounding rock of the next widening area; for the middle widening area, one end of its prefabricated lining structure is connected to the prefabricated lining structure of the previous widening area, and the other end is overlapped with the surrounding rock of the next widening area; for the last widening area, one end of its prefabricated lining structure is connected to the prefabricated lining structure of the previous widening area, and the other end is overlapped with the tunnel arch foot; the second system anchor rods are drilled through the reserved second reserved holes to fix the prefabricated lining structure of each widening area; after processing one widening area, enter the processing flow of the next widening area until all widening areas are processed.

[0082] The invert is then rebuilt and expanded. After all widening areas are processed, the original invert structure is dismantled, and the tunnel is expanded according to the design contour line 10. A prefabricated invert 50 is constructed, one end of which is connected to the first prefabricated lining structure 410, and the other end is connected to the prefabricated lining structure of the last widening area to form a complete tunnel lining structure.

[0083] In the process of removing the initial support and expanding the excavation, the initial support of the remaining area is retained as a temporary support structure, one end of the first prefabricated lining structure 410 is overlapped on the surrounding rock, and one end of the second prefabricated lining in some areas is overlapped on the surrounding rock, so that the first prefabricated lining structure 410 and / or the second prefabricated lining structure 420 and the remaining original lining structure can temporarily form an arch structure to ensure structural stability; by gradually dismantling and expanding each widened area, and then installing the prefabricated lining structure, the construction is orderly and safe; the use of prefabricated lining structures instead of traditional on-site casting greatly improves construction efficiency and shortens construction period.

[0084] Furthermore, the stability of the above structural system depends on the stability of the overlapping surrounding rock, so the surrounding rock at the overlapping location needs to be analyzed for stability. When the bearing capacity is insufficient, grouting reinforcement should be performed in the advanced grouting stage. Furthermore, when assembling the first prefabricated lining structure 410 or the second prefabricated lining structure 420 located in the last widening area, a 10-20 cm concrete cushion layer is preferably laid at the tunnel arch foot. When the first prefabricated lining structure 410 or the second prefabricated lining structure 420 located in the last widening area does not reach the preset position after assembly, a jack can be used to push it to the preset position, and a wedge block can be inserted to increase the overall stability.

[0085] It should be noted that, unlike the New Austrian Tunneling Method (NATM) anchor spraying support, the purpose of spraying concrete onto the surrounding rock wall in this application is to level the surrounding rock wall and reduce the falling of surrounding rock blocks, while the concrete sprayed in the New Austrian Tunneling Method (NATM) is used as a supporting structure in the initial support. Therefore, this application can reduce the usage and solidification time, shortening the construction period.

[0086] As a preferred implementation, the reconstruction and expansion of the remaining tunnel sections in the first direction in step S3 specifically includes the following steps:

[0087] S31, when the surrounding rock grade of the remaining tunnel section is greater than or equal to grade 4, the first area 310 and the second area 320 of the remaining tunnel section with a preset cycle footage are first rebuilt and expanded along the first direction; wherein the arch wall area of ​​each remaining tunnel section is divided into a first area 310, a second area 320, a third area 330 and a fourth area 340 in the widening area in sequence along the tunnel circumference;

[0088] S32, reconstructing and expanding the third area 330 of the remaining tunnel sections of the preset cycle footage along the first direction;

[0089] S33, reconstructing and expanding the fourth area 340 of the remaining tunnel sections of the preset cycle footage along the first direction;

[0090] S34, dismantling the original invert structure corresponding to the preset cycle footage, and expanding the excavation to the design contour line 10, and then constructing the prefabricated invert 50 corresponding to the preset cycle footage;

[0091] Repeat steps S31 to S34 until the reconstruction and expansion of the remaining tunnel sections in the first direction are completed.

[0092] Specifically, Figure 3 As shown, in this embodiment, the arch wall area of ​​each remaining tunnel section is divided into four areas along the tunnel circumference: the first area 310, the second area 320, the third area 330 and the fourth area 340. The second area 320, the third area 330 and the fourth area 340 are all located in the widening area, and the first area 310 is located in the non-widening area; the reconstruction and expansion construction is carried out in the order of the first step formed by the first area 310 and the second area 320, the second step formed by the third area 330, and the third step formed by the fourth area 340. The first step, the second step and the third step are staggered in time and in the longitudinal direction of the tunnel. For example, the second step formed by the third area 330 is started after the first step formed by the first area 310 and the second area 320 completes the reconstruction and expansion of the preset cycle footage. This construction method helps to ensure the continuity and stability of the construction process, while reducing the mutual influence during the construction process.

[0093] By repeating steps S31 to S34, the reconstruction and expansion work of the remaining tunnel sections is gradually promoted. This method makes the construction work more orderly and controllable.

[0094] The preset cycle footage can be the length of every three remaining tunnel sections. The specific length can be set by those skilled in the art according to actual needs. After the renovation and expansion work of each cycle footage is completed, the original invert structure is dismantled and excavated to the designed contour line 10, and then a new prefabricated invert 50 is constructed.

[0095] It is also worth noting that if the surrounding rock grade of the remaining tunnel sections is less than grade four, the reconstruction and expansion steps of the above-mentioned starting section can be referred to; in addition, the process of reconstruction and expansion of the remaining tunnel sections in the second direction can refer to the reconstruction and expansion plan of the above-mentioned first direction, which will not be repeated here.

[0096] As a preferred embodiment, the first area 310 and the second area 320 of the remaining tunnel section of the preset cycle footage are first rebuilt and expanded along the first direction in step S31, specifically including the following steps:

[0097] S311, first remove the initial support of the first area 310 of the current remaining tunnel section and expand the excavation to the design contour line 10, then remove the initial support of the second area 320 and expand the excavation to the design contour line 10, and retain the initial support of the third area 330 and the fourth area 340 as temporary support structures;

[0098] S312, spraying concrete on the surrounding rock wall surfaces of the first area 310 and the second area 320, installing a first prefabricated lining structure 410 matching the first area 310, and a second prefabricated lining structure 420 matching the second area 320; then drilling first system anchor rods through the first reserved holes to fix the first prefabricated lining structure 410, and drilling second system anchor rods through the second reserved holes to fix the second prefabricated lining structure;

[0099] S313, using the first prefabricated lining structure 410 and the second prefabricated lining structure 420 to lay advance support to reinforce the first area 310 and the second area 320 of the next remaining tunnel section;

[0100] S314, repeating steps S311 to S313 to complete the reconstruction and expansion of the first area 310 and the second area 320 of the remaining tunnel sections of the preset cycle footage.

[0101] Specifically, the initial support of the first area 310 of the current remaining tunnel section is removed, and the tunnel is expanded to the design contour line 10. Then, the initial support of the second area 320 is removed, and the tunnel is also expanded to the design contour line 10. During this process, the initial support of the third area 330 and the fourth area 340 is retained as a temporary support structure to ensure the stability of the tunnel during the reconstruction and expansion process.

[0102] The surrounding rock wall surfaces of the first area 310 and the second area 320 that have been expanded to the design contour line 10 are sprayed with concrete to enhance the stability and bearing capacity of the surrounding rock wall surfaces. Then, the matching first prefabricated lining structure 410 and the second prefabricated lining structure 420 are installed to form support in time. The first system anchor rod and the second system anchor rod are respectively driven through the first reserved hole and the second reserved hole to fix the first prefabricated lining structure 410 and the second prefabricated lining structure 420.

[0103] After completing the reconstruction and expansion of the first area 310 and the second area 320 of the current remaining tunnel section, advance support is set up using the already installed first prefabricated lining structure 410 and the second prefabricated lining structure 420. The advance support can be performed by grouting with an advance small conduit through the first prefabricated lining structure 410 and the second prefabricated lining structure 420, which is used to reinforce the first area 310 and the second area 320 of the next remaining tunnel section to ensure the smooth progress of the subsequent reconstruction and expansion work. Among them, the advance small conduit can be connected to the first prefabricated lining structure 410 or the second prefabricated lining structure 420, and then removed when the next remaining tunnel section is reconstructed and expanded.

[0104] As a preferred implementation, the step S32 specifically includes the following steps:

[0105] S321, removing the initial support of the third area 330 of the current remaining tunnel section and expanding the tunnel to the design contour line 10, spraying concrete on the inner wall of the surrounding rock of the third area 330, installing a second prefabricated lining structure 420 matching the third area 330, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure 420;

[0106] S322, using the second prefabricated lining structure 420 to set up advance support to reinforce the third area 330 of the next remaining tunnel section;

[0107] S323, repeating steps S321-S322 to complete the reconstruction and expansion of the third area 330 of the remaining tunnel sections of the preset cycle footage.

[0108] Specifically, the initial support of the third area 330 of the current remaining tunnel section is removed, and the excavation is expanded to the design contour line 10, and concrete is sprayed on the inner wall of the surrounding rock of the third area 330 to enhance the stability and bearing capacity of the surrounding rock. Then, the second prefabricated lining structure 420 matching the third area 330 is installed. The prefabricated lining structure has the advantages of accurate size and controllable quality, which can significantly improve the construction efficiency and quality; the second system anchor rod is set through the second reserved hole to fix the second prefabricated lining structure 420. The function of the second system anchor rod is to tightly connect the lining structure with the surrounding rock to form an overall stable support system. After completing the reconstruction and expansion of the third area 330 of the current remaining tunnel section, the installed second prefabricated lining structure 420 is used to set the advance support. Repeat steps S321 to S322 until the reconstruction and expansion of the third area 330 of the remaining tunnel section with the preset cycle footage is completed. Through step-by-step advancement and cyclic construction, the effective reconstruction and expansion of the third area 330 of the entire remaining tunnel section is achieved.

[0109] As a preferred implementation, the step S33 specifically includes the following steps:

[0110] S331, removing the initial support of the fourth area 340 of the current remaining tunnel section and expanding the tunnel to the design contour line 10 of the fourth area 340, spraying concrete on the inner wall of the surrounding rock of the fourth area 340, installing a second prefabricated lining structure 420 matching the fourth area 340, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure 420;

[0111] S332, using the second prefabricated lining structure 420 to set up advance support to reinforce the fourth area 340 of the next remaining tunnel section;

[0112] S333, repeating steps S331-S332 to complete the reconstruction and expansion of the fourth area 340 of the remaining tunnel sections of the preset cycle footage.

[0113] Specifically, the initial support of the fourth area 340 of the current remaining tunnel section is removed, and the excavation is expanded to the design contour line 10 of the area. After the expansion is completed, the inner wall of the surrounding rock of the fourth area 340 is treated with sprayed concrete to enhance the stability and bearing capacity of the surrounding rock, and the second prefabricated lining structure 420 matching the fourth area 340 is installed. The prefabricated lining structure has the advantages of accurate size and controllable quality, which can significantly improve the construction efficiency and quality. The second system anchor rod is set through the second reserved hole to fix the second prefabricated lining structure 420. After completing the reconstruction and expansion of the fourth area 340 of the current remaining tunnel section, the installed second prefabricated lining structure 420 is used to set the advance support. Repeat steps S331 to S332 until the reconstruction and expansion of the fourth area 340 of the remaining tunnel section with the preset cycle footage is completed. Through gradual advancement and cyclic construction, the effective reconstruction and expansion of the fourth area 340 of the entire remaining tunnel section is achieved.

[0114] Furthermore, the first prefabricated lining structure 410 includes a first steel box 60, the inner wall of the first steel box 60 is provided with a first grouting hole, and ultra-high performance concrete is filled in the first steel box 60 through the first grouting hole to form a first grouting structure layer; the inner wall and the outer wall of the first steel box 60 are both provided with a first reserved hole for the first system anchor rod to pass through, and the first reserved hole on the inner wall of the first steel box 60 and the first reserved hole on the outer wall of the first steel box 60 are arranged in a one-to-one correspondence; wherein, the first system anchor rod includes a first anchoring end and a first locking end, the first anchoring end is anchored into the surrounding rock after passing through the first reserved hole, and the first locking end is connected to the inner wall of the first steel box 60.

[0115] Specifically, after the tunnel is excavated and reaches the design contour line 10, the first steel box 60 is installed in the non-widening area, and ultra-high performance concrete is injected into the first steel box 60 through the first grouting hole. After the concrete solidifies, a first grouting structure layer is formed, which enhances the strength and durability of the lining structure. The first anchoring end of the first system anchor rod is anchored into the surrounding rock through the first reserved hole, and then the first locking end is connected to the inner wall of the first steel box 60 to ensure that the first anchor rod is tightly connected to the first steel box 60 and the surrounding rock. The stability of the tunnel is improved through the combined action of the first system anchor rod and the first grouting structure layer. Ultra-high performance concrete (UHPC) has super high mechanical properties and super durability, and its strength, hardness and durability far exceed those of ordinary concrete; the first prefabricated lining structure 410 uses prefabricated steel boxes, which reduces the workload of on-site construction and shortens the construction period.

[0116] Furthermore, the outer wall of the first steel box 60 can be made of corrugated steel plate, and the first reserved holes and the second reserved holes can be used for pre-grouting before the anchor rod is installed. A small amount of foam concrete can be injected to fill the gap between the corrugated steel plate and the surrounding rock to avoid stress concentration.

[0117] Furthermore, the second prefabricated lining structure 420 includes a second steel box 70, the inner wall of the second steel box 70 is provided with a second grouting hole, and the ultra-high performance concrete is filled in the second steel box 70 through the second grouting hole to form a second grouting structure layer; the inner wall and the outer wall of the second steel box 70 are both provided with a second reserved hole for the second system anchor rod to pass through, and the second reserved holes on the inner wall of the second steel box 70 and the second reserved holes on the outer wall of the second steel box 70 are arranged in a one-to-one correspondence; wherein, the second system anchor rod includes a second anchoring end and a second locking end, the second anchoring end is anchored into the surrounding rock after passing through the second reserved hole, and the second locking end is connected to the inner wall of the second steel box 70.

[0118] Specifically, the second prefabricated lining structure 420 is similar to the first prefabricated lining structure 410, and will not be described in detail herein.

[0119] Furthermore, a first groove 610 and a first protrusion 620 are respectively provided at both ends of the first box body in the longitudinal direction. When the first box body is installed in the longitudinal direction, the first protrusion 620 at the end is inserted into the first groove 610 of the previous first box body, and the first groove 610 at the front end is a reserved slot for installing the next first box body. Preferably, the first groove 610 and the first protrusion 620 are both triangular, with an opening and closing angle of 15°, a thickness of the protruding joint of 4 cm, and a groove depth of 4.2 cm. A second groove 710 and a second protrusion 720 are provided in the circumferential direction of the first box body, and the second groove 710 and the second protrusion 720 can be connected to achieve installation.

[0120] The longitudinal and annular portions of the second box body may also be connected by grooves and protrusions or by bolts, as long as they can be quickly prefabricated and assembled.

[0121] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A construction method for widening one side of an existing tunnel, characterized in that: The following steps are involved: S1, obtaining lining detection information and surrounding rock survey information of an existing tunnel, and determining a starting section for renovation and expansion of the existing tunnel according to the lining detection information and the surrounding rock survey information; wherein the starting section is located in the middle section of the existing tunnel; S2, reconstructing and expanding the starting section, and then using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a first direction, and using the reconstructed and expanded starting section to perform advance support on adjacent tunnel sections in a second direction; wherein the first direction and the second direction are opposite; S3, reconstructing and expanding the remaining tunnel sections in the first direction and reconstructing and expanding the remaining tunnel sections in the second direction to complete the reconstruction and expansion of the built tunnel; The reconstruction and expansion of the starting section in step S2 specifically includes the following steps: S21, first remove the initial support of the non-widened area and expand the excavation to the designed contour line, and retain the initial support of the widened area as a temporary support structure, and then spray concrete on the surrounding rock wall of the non-widened area; wherein the arch wall area of ​​the starting section includes a non-widened area and multiple widened areas that are connected in sequence along the tunnel circumference; S22, installing a first prefabricated lining structure matching the non-widened area; wherein one end of the first prefabricated lining structure overlaps the surrounding rock of the widened area, and the other end overlaps the tunnel arch foot; the first prefabricated lining structure has a first reserved hole for a first system anchor to penetrate; and the first system anchor is driven through the first reserved hole to fix the first prefabricated lining structure; S23, remove the initial support of the i-th widening area and expand the excavation to the design contour line, and retain the initial support of the remaining widening area as a temporary support structure, and then spray concrete on the surrounding rock wall of the i-th widening area; S24, installing a second prefabricated lining structure matching the i-th widening area; wherein, when the i-th widening area is the first widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the first prefabricated lining structure, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and entering step S251; i≥1, i is a positive integer; When i is greater than 1 and the i-th widening area is not the last widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the second prefabricated lining structure of the i-1-th widening area, and the other end is overlapped with the surrounding rock of the i+1-th widening area, and the process goes to step S251; When the i-th widening area is the last widening area, one end of the second prefabricated lining structure of the i-th widening area is connected to the second prefabricated lining structure of the i-1-th widening area, and the other end is overlapped with the tunnel arch foot, and the process proceeds to step S252; S251, drilling a second system anchor through a second reserved hole to fix the second prefabricated lining structure of the i-th widened area, assigning i+1 to i, and then proceeding to step S23; S252, installing a second system anchor through a second reserved hole to fix the second prefabricated lining structure of the i-th widened area; dismantling the original invert structure and expanding the excavation to the designed contour line, and then constructing a prefabricated invert; wherein one end of the prefabricated invert is connected to the first prefabricated lining structure, and the other end is connected to the second prefabricated lining structure of the i-th widened area.

2. The method for reconstruction and expansion of a single-side widening of an existing tunnel according to claim 1, characterized in that: The step S3 of reconstructing and expanding the remaining tunnel sections in the first direction specifically includes the following steps: S31, when the surrounding rock grade of the remaining tunnel section is greater than or equal to grade 4, the first area and the second area of ​​the remaining tunnel section with a preset cycle footage are first rebuilt and expanded along the first direction; wherein the arch wall area of ​​each remaining tunnel section is divided into a first area, a second area located in the widening area, a third area, and a fourth area in sequence along the tunnel circumference; S32, reconstructing and expanding a third area of ​​the remaining tunnel section of the preset cycle footage along the first direction; S33, reconstructing and expanding a fourth area of ​​the remaining tunnel sections of the preset cycle footage along the first direction; S34, dismantling the original invert structure corresponding to the preset cycle footage, expanding the excavation to the designed contour line, and then constructing the prefabricated invert corresponding to the preset cycle footage; Repeat steps S31 to S34 until the reconstruction and expansion of the remaining tunnel sections in the first direction are completed.

3. The construction method for widening one side of an existing tunnel according to claim 2, characterized in that: The step S31 of reconstructing and expanding the first area and the second area of ​​the remaining tunnel section of the preset cycle footage along the first direction specifically includes the following steps: S311, first remove the initial support of the first area of ​​the current remaining tunnel section and expand the excavation to the designed contour line, then remove the initial support of the second area and expand the excavation to the designed contour line, and retain the initial support of the third area and the fourth area as temporary support structures; S312, spraying concrete on the surrounding rock wall surfaces of the first area and the second area, and installing a first prefabricated lining structure matching the first area and a second prefabricated lining structure matching the second area; Then, a first system anchor rod is installed through the first reserved hole to fix the first prefabricated lining structure, and a second system anchor rod is installed through the second reserved hole to fix the second preset lining structure; S313, using the first prefabricated lining structure and the second prefabricated lining structure to lay advance support to reinforce the first area and the second area of ​​the next remaining tunnel section; S314, repeating steps S311 to S313 to complete the reconstruction and expansion of the first area and the second area of ​​the remaining tunnel sections of the preset cycle footage.

4. The construction method for widening one side of an existing tunnel according to claim 2, characterized in that: The step S32 specifically includes the following steps: S321, removing the initial support of the third area of ​​the current remaining tunnel section and expanding the excavation to the design contour line, spraying concrete on the inner wall of the surrounding rock of the third area, installing a second prefabricated lining structure matching the third area, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure; S322, using the second prefabricated lining structure to set up advance support to reinforce the third area of ​​the next remaining tunnel section; S323, repeating steps S321-S322 to complete the reconstruction and expansion of the third area of ​​the remaining tunnel sections of the preset cycle footage.

5. The construction method for widening one side of an existing tunnel according to claim 2, characterized in that: The step S33 specifically includes the following steps: S331, removing the initial support of the fourth area of ​​the current remaining tunnel section and expanding the tunnel to the design contour line of the fourth area, spraying concrete on the inner wall of the surrounding rock of the fourth area, installing a second prefabricated lining structure matching the fourth area, and then driving a second system anchor bolt through the second reserved hole to fix the second prefabricated lining structure; S332, using the second prefabricated lining structure to set up advance support to reinforce the fourth area of ​​the next remaining tunnel section; S333, repeating steps S331-S332 to complete the reconstruction and expansion of the fourth area of ​​the remaining tunnel sections of the preset cycle footage.

6. The construction method for widening one side of an existing tunnel according to claim 1, characterized in that: The first prefabricated lining structure includes a first steel box, the inner wall of the first steel box is provided with a first grouting hole, and ultra-high performance concrete is filled in the first steel box through the first grouting hole to form a first grouting structure layer; the inner wall and the outer wall of the first steel box are both provided with a first reserved hole for the first system anchor rod to pass through, and the first reserved hole on the inner wall of the first steel box and the first reserved hole on the outer wall of the first steel box are arranged in a one-to-one correspondence; wherein, the first system anchor rod includes a first anchoring end and a first locking end, the first anchoring end is anchored into the surrounding rock after passing through the first reserved hole, and the first locking end is connected to the inner wall of the first steel box.

7. The method for reconstruction and expansion of a single-side widening of an existing tunnel according to claim 6, characterized in that: The second prefabricated lining structure includes a second steel box, the inner wall of the second steel box is provided with a second grouting hole, and the ultra-high performance concrete is filled in the second steel box through the second grouting hole to form a second grouting structure layer; the inner wall and the outer wall of the second steel box are both provided with a second reserved hole for the second system anchor rod to pass through, and the second reserved holes on the inner wall of the second steel box and the second reserved holes on the outer wall of the second steel box are arranged in a one-to-one correspondence; wherein, the second system anchor rod includes a second anchoring end and a second locking end, the second anchoring end is anchored into the surrounding rock after passing through the second reserved hole, and the second locking end is connected to the inner wall of the second steel box.

8. The construction method for widening one side of an existing tunnel according to claim 1, characterized in that: The step S23 of spraying concrete on the surrounding rock wall surface of the i-th widening area specifically includes the steps of spraying 8 cm thick C25 concrete on the surrounding rock wall surface of the i-th widening area.

9. The construction method for widening one side of an existing tunnel according to claim 2, characterized in that: The length of the starting section is set between 2 and 5 m, and the length of each remaining tunnel section is set between 2 and 6 m.

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