Construction method of anti-deflection structure of curved middle wall of multi-arch tunnel under topographic bias

Abstract

The application discloses a construction method of a deflection-preventing structure of a curved middle wall of a multi-arch tunnel under terrain bias, and comprises the following steps: excavating and initially supporting a middle pilot hole, and embedding a wall-top hollow anchor rod grouting reinforcement in the top surrounding rock above the middle pilot hole; excavating and supporting left and right side pilot holes of left and right holes respectively, and embedding initial support locking anchor rod grouting reinforcement connected with the support respectively; embedding bottom reinforcement pipe group grouting reinforcement at the bottom of the middle pilot hole; connecting the curved middle wall, the wall-top hollow anchor rod and the bottom reinforcement pipe group into an integral whole, and applying temporary support of the curved middle wall; excavating, supporting and waterproofing the remaining part of the left and right holes, and embedding initial support locking anchor rod grouting reinforcement connected with the support. The construction method has simple construction steps, and when the tunnel is excavated under terrain bias, the curved middle wall is not prone to deflection, crushing and even tunnel surrounding rock or structure instability and damage caused by uneven stress.

Description

Technical Field

[0001] This invention relates to the field of construction technology for arch tunnels, and in particular, to a construction method for an anti-deflection structure for the curved wall of an arch tunnel under terrain bias. Background Technology

[0002] In the construction of transportation engineering projects, numerous large-span tunnel projects involving topographic bias are involved, and the use of arch tunnels is one of the most common methods. The composite curved midwall of arch tunnels is crucial for ensuring the stability of the surrounding rock and structure. The main problems with the curved midwall of arch tunnels in weak and fractured surrounding rock under topographic bias conditions include: uneven stress on the curved midwall caused by tunnel excavation under topographic bias, inducing wall deflection, cracking, and even instability and failure of the surrounding rock or structure. How to solve the deflection of the curved midwall in arch tunnels in weak and fractured surrounding rock under existing topographic bias conditions and enhance its resistance to deflection is an urgent problem to be solved in engineering. Summary of the Invention

[0003] This invention provides a construction method for an anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias, in order to solve the technical problem that the curved wall is prone to deflection, cracking, or even instability and damage to the surrounding rock or structure of the tunnel due to uneven stress during tunnel excavation under terrain bias.

[0004] The technical solution adopted in this invention is as follows:

[0005] A construction method for an anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias is characterized by the following steps: S10: Excavation and initial support of the central pilot tunnel, and grouting reinforcement of the wall top hollow anchor rods embedded in the surrounding rock above the central pilot tunnel; S20: Excavation and support of the left pilot tunnel of the left tunnel and the right pilot tunnel of the right tunnel, and grouting reinforcement of the initial support locking anchor rods connected to the support; S30: Grouting reinforcement of the bottom reinforcement pipe group embedded at the bottom of the central pilot tunnel; S40: Construction of the curved wall connected to the wall top hollow anchor rods and the bottom reinforcement pipe group to form a whole, and construction of temporary support for the curved wall; S50: Excavation, support and waterproofing construction of the remaining parts of the left and right tunnels, and grouting reinforcement of the initial support locking anchor rods connected to the support.

[0006] Furthermore, in step S10, there are multiple hollow anchor rods at the top of the wall, arranged radially at intervals. Each hollow anchor rod includes a hollow anchor body, a plastic expansion shell connected to the driving end of the hollow anchor body, an anchor connected to the grouting end of the hollow anchor body, and an exhaust pipe for venting air during grouting. A grouting hole penetrating the wall is opened on the wall surface of the hollow anchor body, and the grouting end of the hollow anchor body is used to connect with the structural reinforcement at the top of the curved wall through the anchor. Its opposite driving end is driven upward into the top surrounding rock, and expands under force through the plastic expansion shell to enhance the pull-out resistance. One end of the exhaust pipe is located between the hollow anchor body and the anchor hole, and its opposite end extends out of the anchor hole.

[0007] Further, step S20 specifically includes the following steps: advance support of the upper part of the left pilot tunnel; excavation of the upper step of the left pilot tunnel; initial support and temporary support of the left pilot tunnel, and grouting reinforcement of the initial support locking anchor bolts embedded in the wall of the left pilot tunnel; advance support of the upper part of the right pilot tunnel; excavation of the upper step of the right pilot tunnel; initial support and temporary support of the right pilot tunnel, and grouting reinforcement of the initial support locking anchor bolts embedded in the wall of the right pilot tunnel.

[0008] Furthermore, in step S20, there are multiple initial support locking anchor rods, which are arranged radially at intervals; the structure of each initial support locking anchor rod is the same as the structure of the hollow anchor rod at the top of the wall.

[0009] Furthermore, the bottom reinforcement pipe assembly in step S30 includes grouted guide pipes for reinforcing the bottom foundation of the curved wall, and grouted steel pipe piles for enhancing the connection strength between the curved wall and the bottom surrounding rock. There are multiple grouted guide pipes, which are arranged radially at intervals, and the upper end of each grouted guide pipe is used to connect to the inside of the curved wall, while its lower end is driven downward into the bottom foundation. There are also multiple grouted steel pipe piles, which are arranged radially at intervals, and the upper end of each grouted steel pipe pile is used to connect to the inside of the curved wall, while its lower end is driven downward into the bottom surrounding rock.

[0010] Furthermore, the grouting rod includes a hollow grouting rod body, with a grout leakage hole penetrating the wall surface on the wall surface, and the driving end of the grouting rod body extends into a cone, with its opposite grouting end opening to allow grout to be injected into the grouting rod body.

[0011] Furthermore, the grouting steel pipe pile includes a hollow steel pipe body and a reinforcing cage for enhancing the structural strength and rigidity of the grouting steel pipe pile; the wall of the steel pipe body is provided with a grout outlet hole that penetrates the wall, and the driving end of the steel pipe body extends into a cone shape, with its opposite grouting end opening to allow grout to be injected into the steel pipe body; the reinforcing cage extends along the length of the steel pipe body and is arranged inside the steel pipe body.

[0012] Further, step S40 specifically includes the following steps: binding the structural reinforcement of the curved wall and connecting and fixing the structural reinforcement to the hollow anchor rod at the top of the wall and the bottom reinforcing pipe assembly respectively; casting the curved wall; and constructing temporary supports for the curved wall.

[0013] Furthermore, the structural reinforcement includes circumferential steel bars for constructing the outer framework of the curved wall. The outer framework includes two side wall frames located on both sides, and a top frame and a bottom frame arranged opposite each other and connected to the two side wall frames respectively. The structural reinforcement of the curved wall also includes longitudinal steel bars that are sequentially spaced along the outer perimeter of the outer framework and extend longitudinally, transverse stirrups connecting the two side wall frames, and reinforcing stirrups for enhancing the overall strength of the structure. The reinforcing stirrups are connected between the top frame and the two side wall frames, and between the bottom frame and the two side wall frames.

[0014] Further, step S50 includes the construction of the remaining parts of the left tunnel and the right tunnel; the construction of the remaining parts of the left tunnel includes: the upper pre-support of the left main tunnel; the excavation and initial support of the upper bench of the left main tunnel; the excavation of the lower bench of the left pilot tunnel; the initial support and temporary support of the lower part of the left pilot tunnel; the excavation of the lower bench of the left main tunnel; the initial support of the lower part of the left main tunnel; the construction of the left invert arch; the construction of the waterproof layer and the secondary lining of the arch wall of the left tunnel; the construction of the remaining parts of the right tunnel includes: the upper pre-support of the right main tunnel; the excavation and initial support of the upper bench of the right main tunnel; the excavation of the lower bench of the right pilot tunnel; the initial support and temporary support of the lower part of the right pilot tunnel; the excavation of the lower bench of the right main tunnel; the initial support of the lower part of the right main tunnel; the construction of the right invert arch; the construction of the waterproof layer and the secondary lining of the arch wall of the right tunnel.

[0015] The present invention has the following beneficial effects:

[0016] The construction method of this invention has simple construction steps. When excavating tunnels under terrain bias, it is less likely to cause wall deflection, cracking, or even instability and damage to the tunnel surrounding rock or structure due to uneven stress in the curved wall. The anti-deflection structure of the curved wall of the arch tunnel under terrain bias constructed using the construction method of this invention includes the curved wall, left tunnel, right tunnel, hollow anchor bolts at the top of the wall, bottom reinforcement pipe assembly, and initial support locking anchor bolts. It is suitable for complex bias geological conditions and has the characteristics of wide applicability, good overall structural stability, and strong anti-deflection performance. In the structure of this invention, the initial support locking anchor bolts are constructed simultaneously during the construction of the left and right tunnels, so that the construction... The initial support locking anchors are driven into the surrounding rock from the left and right tunnels respectively, changing the curved wall from a "concentrated bias pressure" stress state to a "distributed bias pressure" stress state. This limits the relative sliding between the initial lining of the left and right tunnels and the surrounding rock, achieving coordinated deformation between the lining structure and the surrounding rock. In the structure of this invention, a hollow anchor is installed between the top of the curved wall and the top surrounding rock, and a bottom reinforcement pipe assembly is installed between the bottom of the curved wall and the bottom surrounding rock for reinforcement. This fully ensures that the curved wall and the surrounding rock form an integral whole, thereby enhancing the curved wall's ability to withstand bias loads and resist deflection, and improving the load-bearing performance and stability of the curved wall.

[0017] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 This is a schematic diagram of the anti-deflection structure of the curved wall of the arch tunnel under terrain bias constructed using the construction method of this invention;

[0020] Figure 2 This is a schematic diagram of the reinforcement of the curved wall structure in the construction method of this invention;

[0021] Figure 3 This is a schematic diagram of the working state of the hollow anchor rod at the top of the wall in the construction method of this invention;

[0022] Figure 4 This is a schematic diagram of the grouting rod structure in the construction method of this invention;

[0023] Figure 5 yes Figure 4 Schematic diagram of the grouting rod layout for the central guide tube;

[0024] Figure 6 This is a schematic diagram of the grouting steel pipe pile structure in the construction method of this invention;

[0025] Figure 7 yes Figure 6 A schematic diagram of the left-side view structure;

[0026] Figure 8 This is a schematic diagram of the construction steps of the construction method for the anti-deflection structure of the curved wall in a continuous arch tunnel under terrain bias, according to the present invention.

[0027] Legend

[0028] 10. Left tunnel; 20. Right tunnel; 30. Curved wall; 301. Circumferential reinforcement; 302. Longitudinal reinforcement; 303. Transverse stirrups; 304. Reinforcing stirrups; 40. Top surrounding rock; 50. Hollow anchor rod at the top of the wall; 501. Grouting hole; 51. Hollow anchor rod body; 52. Plastic expansion shell; 53. Anchor; 54. Vent pipe; 60. Bottom surrounding rock; 70. Grouting rod guide pipe; 701. Leakage hole; 702. Reserved grout-stopping section; 71. Grouting rod body; 80. Grouting steel pipe pile; 801. Grout outlet hole; 81. Steel pipe body; 82. Reinforcing cage; 90. Initial support locking anchor rod; 110. External surrounding rock; 120. Central guide tunnel. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0030] Reference Figure 1 and Figure 8 A preferred embodiment of the present invention provides a construction method for an anti-deflection structure of a curved wall in a multi-arch tunnel under terrain bias, comprising the following steps:

[0031] S10: Excavation and initial support of the central pilot tunnel 120, and grouting reinforcement of the wall top hollow anchor rod 50 in the top surrounding rock 40 above the central pilot tunnel 120;

[0032] S20: Excavation and support of the left pilot tunnel of left tunnel 10 and the right pilot tunnel of right tunnel 20, and grouting reinforcement of the initial support locking anchor bolts 90 connected to the support.

[0033] S30: Grouting reinforcement of the bottom reinforcement pipe group buried at the bottom of the central pilot tunnel 120;

[0034] S40: Connect the curved wall 30 to the hollow anchor rod 50 at the top of the wall and the bottom reinforcement pipe assembly to form a whole, and provide temporary support for the curved wall 30;

[0035] S50: Excavation, support and waterproofing of the remaining parts of left tunnel 10 and right tunnel 20, and grouting reinforcement of the initial support locking anchor rods 90 connected to the support.

[0036] In the construction method of the anti-deflection structure of the curved wall of the arch tunnel under terrain bias pressure of the present invention, during the excavation and support construction of the left pilot tunnel of the left tunnel 10 and the right pilot tunnel of the right tunnel 20, the initial support locking anchor rods 90 are simultaneously constructed and grouted for reinforcement. Furthermore, during the excavation, support, and waterproofing construction of the remaining parts of the left tunnel 10 and right tunnel 20, the initial support locking anchor rods 90 connected to the support are simultaneously buried and grouted for reinforcement. This allows the constructed initial support locking anchor rods 90 to be driven into the external surrounding rock 110 from the left tunnel 10 and right tunnel 20 respectively, thereby enhancing the connection stability between the left tunnel 10 and right tunnel 20 and the external surrounding rock 110, and changing the previous "concentrated bias pressure" stress state of the curved wall 30. The structure is transformed into a "distributed biased pressure" stress state, which effectively limits the relative sliding between the initial support of the left tunnel 10 and the right tunnel 20 and the external surrounding rock, and realizes the coordinated deformation of the structure and the external surrounding rock. At the same time, during the excavation and initial support construction of the central tunnel 120, hollow anchor rods 50 are embedded in the top surrounding rock 40 above the central tunnel 120 for grouting reinforcement, and bottom reinforcement pipe groups are embedded at the bottom of the central tunnel 120 for grouting reinforcement. The curved wall 30 is connected to the hollow anchor rods 50 and the bottom reinforcement pipe groups to form a whole, thereby enhancing the ability of the curved wall 30 to withstand biased loads and resist deflection, and improving the bearing capacity and stability of the curved wall 30.

[0037] The construction method of this invention has simple construction steps. When excavating a tunnel under terrain bias, it is less likely to cause the curved wall to deflect, crack, or even cause instability and damage to the surrounding rock or structure due to uneven stress. The anti-deflection structure of the curved wall of a multi-arch tunnel under terrain bias constructed using the construction method of this invention includes a curved wall 30, a left tunnel 10, a right tunnel 20, a hollow anchor rod 50 at the top of the wall, a bottom reinforcement pipe assembly, and an initial support locking anchor rod 90. It is suitable for complex bias geological conditions and has the characteristics of wide applicability, good overall structural stability, and strong anti-deflection performance. In the structure of this invention, the initial support locking anchor rod 90 is constructed simultaneously during the construction of the left tunnel 10 and the right tunnel 20, so that the constructed initial support locking anchor rods 90 is driven into the surrounding rock 110 by the left tunnel 10 and the right tunnel 20 respectively, so that the curved wall 30 changes from a "concentrated bias pressure" stress state to a "distributed bias pressure" stress state, thereby limiting the relative sliding between the initial lining of the left tunnel 10 and the right tunnel 20 and the surrounding rock, and realizing the coordinated deformation of the lining structure and the surrounding rock. In the structure of the present invention, a hollow anchor rod 50 is set between the top of the curved wall 30 and the top surrounding rock 40, and a bottom reinforcement pipe group is set between the bottom of the curved wall 30 and the bottom surrounding rock 60 for reinforcement treatment, so as to fully ensure that the curved wall 30 and the surrounding rock form an integral whole, thereby enhancing the ability of the curved wall 30 to withstand bias loads and resist deflection, and improving the bearing performance and stability of the curved wall 30.

[0038] Optionally, such as Figure 1 As shown, in step S10, there are multiple hollow anchor rods 50 at the top of the wall, which are arranged radially at intervals, so that both the hollow anchor rods 50 and the curved wall 30 can be subjected to uniform force, thereby improving the stress state of the hollow anchor rods 50 and the curved wall 30.

[0039] In this optional solution, such as Figure 1 and Figure 3 As shown, each hollow anchor rod 50 at the top of the wall includes a hollow anchor rod body 51, a plastic expansion shell 52 connected to the driving end of the hollow anchor rod body 51, an anchor 53 connected to the grouting end of the hollow anchor rod body 51, and an exhaust pipe 54 for venting air during grouting. A grouting hole 501 penetrating the wall is provided on the wall surface of the hollow anchor rod body 51, and the grouting end of the hollow anchor rod body 51 is used to connect with the structural reinforcement at the top of the curved wall 30 through the anchor 53. Its opposite driving end is driven upward into the top surrounding rock 40, and the plastic expansion shell 52 expands under force to enhance the pull-out resistance. One end of the exhaust pipe 54 is located between the hollow anchor rod body 51 and the anchor hole, and its opposite end extends out of the anchor hole.

[0040] In the above scheme, the hollow anchor body 51 acts as a tie rod; the plastic expansion shell 52 can enhance the pull-out resistance after being stretched and expanded; the hollow anchor 50 at the top of the wall is tightly connected to the surrounding rock 40 at the top by grouting, which increases the friction of the hollow anchor 50 at the top of the wall to give full play to the self-supporting role of the surrounding rock; the anchor 53 includes a steel pad and a fixing nut installed sequentially on the outer circle of the grouting end of the hollow anchor body 51, which work together to anchor; the plastic vent pipe 54 plays a role in venting during the grouting of the hollow anchor 50 at the top of the wall, which facilitates the injection of cement grout. Hollow anchor rods 50 are embedded in the top surrounding rock 40 of the curved wall 30 by drilling holes. Cement grout is injected into the hollow anchor rods 50 to fully contact the top surrounding rock 40 and enhance the friction. The end plastic expansion shell 52 can increase the pull-out resistance after being stretched. The tail of the hollow anchor rod 50 is anchored to the structural reinforcement of the curved wall 30 through steel pads and fixing nuts. The top surrounding rock 40 and the curved wall 30 are connected to form a whole by relying on the hollow anchor rods 50, thereby improving its integrity and stability. Specifically, the diameter of the hollow anchor rod 50 at the top of the wall is approximately 25mm, and the length penetrating into the surrounding rock should not be less than 2.5m; the anchor rod holes are constructed using cross or button drill bits, with a diameter of approximately 42mm and a length of 4.5m, arranged at circumferential × longitudinal spacing of 800mm × 800mm; grouting uses a DML30-2 type anchor rod special grouting pump, with a grouting pressure of approximately 0.5~1.0MPa; the cement grouting body uses pure cement slurry, with a water-cement ratio (WC) between 0.45 and 0.30:1; when grouting upwards, a one-way injectable grout stop plug or direct grouting pipe can be used for grouting.

[0041] Optionally, such as Figure 8 As shown, step S20 specifically includes the following steps:

[0042] Advanced support for the upper part of the left pilot tunnel;

[0043] Excavation of the steps leading up to the left pilot tunnel;

[0044] Initial support and temporary support for the left pilot tunnel, and grouting reinforcement with initial support locking anchor bolts 90mm in the wall of the left pilot tunnel;

[0045] Advance support for the upper part of the right-side pilot tunnel;

[0046] Excavation of the upper step of the right-side pilot tunnel;

[0047] Initial support and temporary support for the right-side pilot tunnel, and initial support locking anchor rods 90mm were installed in the wall of the right-side pilot tunnel for grouting reinforcement.

[0048] Specifically, step S20 is simple to construct. By first excavating, initially supporting, and temporarily supporting the upper steps of the left and right pilot tunnels, the impact of construction on the central pilot tunnel 120 is effectively avoided, and the stability of the central pilot tunnel 120 is improved.

[0049] Optionally, such as Figure 1 As shown, the number of initial support locking anchor rods 90 in step S20 is multiple, and the multiple initial support locking anchor rods 90 are arranged radially at intervals. In this optional scheme, the grouting end of each initial support locking anchor rod 90 is welded and fixed to the support during the construction of the left tunnel 10 and the right tunnel 20, and its opposite driving end is driven into the surrounding rock 110 by the sidewall and arch of the left tunnel 10 and the right tunnel 20 respectively, so that the left tunnel 10, the right tunnel 20 and the initial support locking anchor rods 90 can be evenly stressed, thereby improving the stress state of the left tunnel 10, the right tunnel 20 and the initial support locking anchor rods 90.

[0050] In this optional scheme, the structure of the initial support locking anchor 90 is the same as that of the hollow anchor 50 at the top of the wall, and the tail of the initial support locking anchor 90 is welded firmly to the support during the construction of the left tunnel 10 and the right tunnel 20, so that the external surrounding rock 110 and the initial support structure form an integral whole.

[0051] Optionally, such as Figure 1 As shown, the bottom reinforcement pipe assembly in step S30 includes a grouted guide pipe 70 for reinforcing the bottom foundation of the curved wall 30, and a grouted steel pipe pile 80 for enhancing the connection strength between the curved wall 30 and the bottom surrounding rock 60. There are multiple grouted guide pipes 70, which are arranged radially at intervals. The upper end of each grouted guide pipe 70 is used to connect to the curved wall 30, and its lower end is driven downward into the bottom foundation. There are also multiple grouted steel pipe piles 80, which are arranged radially at intervals. The upper end of each grouted steel pipe pile 80 is used to connect to the curved wall 30, and its lower end is driven downward into the bottom surrounding rock 60.

[0052] In this optional solution, such as Figure 1 and Figure 4 As shown, the grouting rod 70 includes a hollow grouting rod body 71. A grout leakage hole 701 penetrating the wall surface is provided on the wall of the grouting rod body 71, and the driving end of the grouting rod body 71 extends into a cone shape, with its opposite grouting end opening to allow grout to be injected into the grouting rod body 71. In this optional solution, such as... Figure 4 and Figure 5As shown, the grouting rod 71 is a steel pipe, mainly serving as reinforcement and load-bearing. Grout is injected into the steel pipe through the grouting port on the grouting rod 71. The grout leakage hole 701 allows the grout to seep into the surrounding rock through the steel pipe, forming a grout body that integrates with the surrounding rock. The driving end of the steel pipe extends into a cone shape to facilitate driving the pipe in. A section of the steel pipe near its grouting end does not have a grout leakage hole 701 to form a reserved grout stop section 702. This reserved grout stop section ensures grouting pressure loss and prevents grout leakage from the pipe opening, facilitating grout injection. By installing the guide grouting rod 70 in the foundation at the bottom of the curved wall 30, with several pre-drilled grout leakage holes 701 on the steel pipe, after the steel pipe is inserted into the foundation, the grout seeps into the surrounding rock through the grout leakage holes 701 through the grouting action, forming a whole with the surrounding rock. Reinforcing the foundation at the bottom of the curved wall 30 using the guide grouting rod 70 can improve the bearing capacity and resistance to uneven deformation of the foundation. Specifically, the steel pipe is a hot-rolled seamless steel perforated pipe with an outer diameter of 50mm, a wall thickness of 5mm, and a length of 4m; for example Figure 5 As shown, the grouting rods 70 are arranged in a quincunx pattern with a spacing of 500*500mm and an external insertion angle of about 3-5°; the grout leakage holes 701 have a diameter of about 8mm, a hole spacing of 150mm, and are arranged in a quincunx pattern, with the front end processed into a cone shape; the grouting body is made of cement grout with a water-cement ratio of 0.5:1 to 1:1 and a grouting pressure of about 0.5-1MPa, or determined according to field tests.

[0053] In this optional solution, such as Figure 1 and Figure 6 , Figure 7 As shown, the grouting steel pipe pile 80 includes a hollow steel pipe body 81 and a reinforcing cage 82 for enhancing the structural strength and rigidity of the grouting steel pipe pile 80; the wall surface of the steel pipe body 81 is provided with a grout outlet hole 801 that penetrates the wall surface, and the driving end of the steel pipe body 81 extends into a cone, with its opposite grouting end open to allow grout to be injected into the steel pipe body 81; the reinforcing cage 82 extends along the length direction of the steel pipe body 81 and is arranged inside the steel pipe body 81.

[0054] In the above scheme, such as Figure 6 and Figure 7As shown, the steel pipe body 81 and the reinforcing cage 82 mainly serve as reinforcement, enhancing the strength and rigidity of the pile. The grout outlet 801 on the steel pipe body 81 serves to leak grout, facilitating the leakage of grout from the steel pipe body 81 to form a grouting body, which then integrates with the bottom surrounding rock 60. The grouting steel pipe pile 80 has high overall rigidity and flexible arrangement. By symmetrically arranging several grouting steel pipe piles 80 in the foundation at the bottom of the curved wall 30, the overall effect between the curved wall 30 and the bottom surrounding rock 60 can be further enhanced, improving the anti-deflection performance of the curved wall 30. Specifically, grouting holes 801 are drilled in the steel pipe pile 81, with a diameter of 0.8-1.5cm and a spacing of about 15cm. After the steel pipe pile 81 and the reinforcing cage 82 are hoisted in, M30 grout is used to fill the holes, and the grouting pressure can be 0.3-0.5MPa. After grout overflows from both inside and outside the steel pipe pile 81, the hole is sealed and pressurized for a period of time. Grouting is stopped after the grout overflows again. The section of the steel pipe pile 81 without drilling should be greater than 1.0m. The diameter of the grouting steel pipe pile 80 can be 10-30cm, and the specific parameters are determined according to the actual project.

[0055] Optionally, such as Figure 8 As shown, step S40 specifically includes the following steps:

[0056] The structural reinforcement of the curved wall 30 is tied, and the structural reinforcement is connected and fixed to the hollow anchor rod 50 at the top of the wall and the bottom reinforcement pipe assembly respectively;

[0057] Cast-in-place curved wall 30;

[0058] Temporary support for the 30-meter-long wall in the middle of the composition.

[0059] In this optional solution, such as Figure 1 and Figure 2 As shown, the structural reinforcement includes circumferential steel bars 301 for constructing the external framework of the curved wall 30. The external framework includes two side wall frames located on both sides, and a top frame and a bottom frame arranged vertically opposite to each other and connected to the two side wall frames respectively. The structural reinforcement of the curved wall 30 also includes longitudinal steel bars 302 arranged at intervals along the outer perimeter of the external framework and extending longitudinally, transverse stirrups 303 connecting the two side wall frames, and reinforcing stirrups 304 for enhancing the overall strength of the structure. The reinforcing stirrups 304 connect the top frame to the two side wall frames, and the bottom frame to the two side wall frames. The curved wall 30 has a simple structure and is easy to manufacture. In this optional scheme, diagonal reinforcing stirrups 304 are respectively arranged at the wall shoulder and wall foot of the curved wall 30 to enhance the compressive and torsional resistance of the curved wall 30. In this optional scheme, the type and size of the steel bars in the circumferential steel bars 301, longitudinal steel bars 302, transverse stirrups 303 and reinforcing stirrups 304 can be referenced. Figure 2 As shown, the specific details can also be determined based on the actual project.

[0060] Optionally, such as Figure 8As shown, step S50 includes the construction of the remaining part of the left tunnel 10 and the construction of the remaining part of the right tunnel 20;

[0061] The remaining construction work for Left Tunnel 10 includes: advanced support for the upper part of the main tunnel of Left Tunnel 10; excavation and initial support of the upper bench of the main tunnel of Left Tunnel 10; excavation of the lower bench of the left pilot tunnel; initial support and temporary support of the lower part of the left pilot tunnel; excavation of the lower bench of the main tunnel of Left Tunnel 10; initial support of the lower part of the main tunnel of Left Tunnel 10; construction of the invert arch of Left Tunnel 10; construction of the waterproof layer and pouring of the secondary lining of the arch wall of Left Tunnel 10.

[0062] The remaining construction work for Right Tunnel 20 includes: advanced support for the upper part of the main tunnel of Right Tunnel 20; excavation and initial support of the upper bench of the main tunnel of Right Tunnel 20; excavation of the lower bench of the right pilot tunnel; initial support and temporary support of the lower part of the right pilot tunnel; excavation of the lower bench of the main tunnel of Right Tunnel 20; initial support of the lower part of the main tunnel of Right Tunnel 20; construction of the invert arch of Right Tunnel 20; construction of the waterproof layer and secondary lining of the arch wall of Right Tunnel 20.

[0063] In the construction method of this invention, the construction should be carried out in strict accordance with the principles of "pipe advance, strict grouting, short excavation, strong support, frequent measurement, and early closure" to ensure construction safety. Figure 8 The construction sequence shown is as follows: first construct the shallow-buried side tunnel, then the deep-buried side tunnel, with the construction sequence being symmetrical. The preceding tunnel should be at least 30m ahead of the following tunnel in length, and the distance between the upper and lower steps in a single tunnel should not exceed 20m. Secondary lining pouring should be carried out promptly, and there should be no situation where both the preceding and following tunnels only have initial support. When pouring the curved wall, grouting pipes should be reserved at the top of the curved wall. After the curved wall is poured, the top of the curved wall should be inspected, and if there are voids, they should be grouted to compact them. Before excavating the main tunnels of the left and right tunnels, it must be ensured that there are no voids at the top of the curved wall. Initial support should be implemented in a timely manner, and on-site monitoring should be strengthened. If deformation cannot converge under the specified conditions, The support structure should be strengthened. The spacing of the I-beams in the initial support of the pilot tunnel should, in principle, be the same as that in the main tunnel, depending on the surrounding rock conditions. The spacing can be adjusted according to the actual geological conditions. To ensure tunnel stability and construction safety, considering the spacing of the steel arch frames and the working space, it is recommended that the excavation advance be 0.5–1m per cycle. Steel frames, wire mesh, and shotcrete support should be erected promptly, and the initial support should be closed into a ring as soon as possible. Based on geological conditions and measurement results, temporary invert arches should be added and the spacing of temporary vertical supports adjusted when necessary. The length of temporary support removed and the lining constructed each time should not exceed 6m. On-site monitoring and measurement are essential and should be implemented throughout the entire construction process.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A construction method for an anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias, characterized in that, Includes the following steps: S10: Excavation and initial support of the central tunnel (120), and grouting reinforcement of the wall top hollow anchor rod (50) in the top surrounding rock (40) above the central tunnel (120); S20: Excavation and support of the left guide tunnel of the left tunnel (10) and the right guide tunnel of the right tunnel (20), and grouting reinforcement of the initial support locking anchor rod (90) connected to the support respectively; the specific steps include: advance support of the upper part of the left guide tunnel; excavation of the upper step of the left guide tunnel; initial support and temporary support of the left guide tunnel, and grouting reinforcement of the initial support locking anchor rod (90) in the wall of the left guide tunnel; advance support of the upper part of the right guide tunnel; excavation of the upper step of the right guide tunnel; initial support and temporary support of the right guide tunnel, and grouting reinforcement of the initial support locking anchor rod (90) in the wall of the right guide tunnel; S30: Grouting reinforcement of the bottom of the central guide tunnel (120) is carried out; S40: Connect the curved wall (30) to the hollow anchor rod (50) at the top of the wall and the bottom reinforcing pipe assembly to form a whole, and construct temporary support for the curved wall (30); specifically including the following steps: binding the structural reinforcement of the curved wall (30), and connecting and fixing the structural reinforcement to the hollow anchor rod (50) at the top of the wall and the bottom reinforcing pipe assembly respectively; casting the curved wall (30); constructing temporary support for the curved wall (30); S50: Excavation, support and waterproofing of the remaining parts of the left tunnel (10) and right tunnel (20), and grouting reinforcement of the initial support locking anchor rods (90) connected to the support; Step S50 includes the construction of the remaining parts of the left tunnel (10) and the right tunnel (20); The construction of the remaining parts of the left tunnel (10) includes: the upper pre-support of the main tunnel of the left tunnel (10); the excavation and initial support of the upper bench of the main tunnel of the left tunnel (10); the excavation of the lower bench of the left guide tunnel; the initial support and temporary support of the lower part of the left guide tunnel; the excavation of the lower bench of the main tunnel of the left tunnel (10); The construction of the left tunnel (10) includes the initial support of the lower part of the main tunnel; the construction of the invert arch of the left tunnel (10); the construction of the waterproof layer and the secondary lining of the arch wall of the left tunnel (10); the construction of the remaining part of the right tunnel (20) includes: the advanced support of the upper part of the main tunnel of the right tunnel (20); the excavation and initial support of the upper step of the main tunnel of the right tunnel (20); the excavation of the lower step of the right guide tunnel; the initial support and temporary support of the lower part of the right guide tunnel; the excavation of the lower step of the main tunnel of the right tunnel (20); the initial support of the lower part of the main tunnel of the right tunnel (20); the construction of the invert arch of the right tunnel (20); the construction of the waterproof layer and the secondary lining of the arch wall of the right tunnel (20).

2. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 1, characterized in that, The number of hollow anchor rods (50) at the top of the wall in step S10 is multiple, and the multiple hollow anchor rods (50) at the top of the wall are arranged radially at intervals; Each of the hollow anchor rods (50) on the top of the wall includes a hollow anchor rod body (51), a plastic expansion shell (52) connected to the driving end of the hollow anchor rod body (51), an anchor (53) connected to the grouting end of the hollow anchor rod body (51), and an exhaust pipe (54) for venting air during grouting. The hollow anchor body (51) has a grouting hole (501) that penetrates the wall surface. The grouting end of the hollow anchor body (51) is used to connect with the structural reinforcement at the top of the curved wall (30) through the anchor (53). Its opposite driving end is driven upward into the top surrounding rock (40). The plastic expansion shell (52) expands under force to enhance the pull-out resistance. One end of the exhaust pipe (54) is located between the hollow anchor body (51) and the anchor hole, and the other end extends out of the anchor hole.

3. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 1, characterized in that, The number of the initial support locking anchor rods (90) in step S20 is multiple, and the multiple initial support locking anchor rods (90) are arranged radially at intervals; The structure of each of the initial support locking anchor rods (90) is the same as that of the hollow anchor rod (50) at the top of the wall.

4. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 1, characterized in that, The bottom reinforcement pipe assembly in step S30 includes a grouting pipe rod (70) for reinforcing the bottom foundation of the curved wall (30), and a grouting steel pipe pile (80) for enhancing the connection strength between the curved wall (30) and the bottom surrounding rock (60). The number of the grouting rods (70) is multiple, and the multiple grouting rods (70) are arranged radially at intervals. The upper end of each grouting rod (70) is used to connect to the curved wall (30), and its opposite lower end is driven downward into the bottom foundation. The number of grouting steel pipe piles (80) is multiple, and the multiple grouting steel pipe piles (80) are arranged radially at intervals. The upper end of each grouting steel pipe pile (80) is used to connect to the curved wall (30), and its opposite lower end is driven downward into the bottom surrounding rock (60).

5. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 4, characterized in that, The grouting rod (70) includes a hollow grouting rod body (71), and the wall surface of the grouting rod body (71) is provided with a grout leakage hole (701) that penetrates the wall surface. The driving end of the grouting rod body (71) extends into a cone, and its opposite grouting end is open to allow grout to be injected into the grouting rod body (71).

6. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 4, characterized in that, The grouting steel pipe pile (80) includes a hollow steel pipe body (81) and a steel cage (82) for enhancing the structural strength and rigidity of the grouting steel pipe pile (80); The steel pipe body (81) has a grout outlet (801) that penetrates the wall surface, and the driving end of the steel pipe body (81) extends into a cone, with its opposite grouting end opening to allow grout to be injected into the steel pipe body (81). The reinforcing cage (82) extends along the length of the steel pipe (81) and is arranged inside the steel pipe (81).

7. The construction method for the anti-deflection structure of the curved wall in a multi-arch tunnel under terrain bias as described in claim 1, characterized in that, The structural reinforcement includes circumferential steel bars (301) for constructing the outer skeleton of the curved wall (30). The outer skeleton includes two side wall frames located on both sides, and a top frame and a bottom frame arranged opposite to each other and connected to the two side wall frames respectively. The structural reinforcement of the curved wall (30) also includes longitudinal steel bars (302) that are arranged at intervals along the outer perimeter of the outer frame and extend longitudinally, transverse stirrups (303) that connect the two side wall frames, and reinforcing stirrups (304) that enhance the overall strength of the structure. The reinforcing stirrup (304) is connected between the top frame and the two side wall frames, and between the bottom frame and the two side wall frames.

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