Tunnel excavation construction method

Abstract

The present invention provides a tunnel excavation construction method, which includes: inserting an advance support steel pipe into the head working face along the tunnel contour line to obtain an advance support area located in front of the head working face; within the advance support area, moving the head working face forward by an excavation distance to obtain a tunnel section to be supported located behind the head working face; temporarily supporting the tunnel section to be supported to obtain a temporary support tunnel section; permanently supporting the temporary support tunnel section to obtain a permanent support tunnel section; and repeatedly performing the above tunnel excavation steps until tunnel excavation is completed. The technical solution provided by this application can solve the problem in the related art that the solidification effect of grouting to reinforce the gravel aquifer to be excavated is not ideal, making it difficult to perform tunneling construction in the gravel aquifer.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a tunnel excavation construction method. Background Art

[0002] The return air inclined shaft of a coal mine begins to expose a gravel aquifer near the wellhead. Further excavation of the return air inclined shaft needs to be carried out in the gravel aquifer. At this time, the gravel aquifer causes the water inflow of the wellbore to increase, and the gravel aquifer is prone to spalling and collapse, which has a great impact on the excavation of the return air inclined shaft.

[0003] In the related art, a hole is drilled into the gravel aquifer to be excavated, and a solidifying slurry is injected into the gravel aquifer to be excavated, so as to reinforce the gravel aquifer to be excavated.

[0004] However, due to the high water content of the gravel aquifer, the hole is prone to collapse during drilling, making it difficult to inject slurry. In addition, the slurry after grouting is easily washed away by water and quicksand, making the solidification range of the slurry unstable. As a result, the solidification effect of the grouting solidification used in the related technology to reinforce the gravel aquifer to be excavated is not ideal, and it is not easy to carry out excavation construction in the gravel aquifer. Summary of the Invention

[0005] The present invention provides a tunnel excavation construction method to solve the problem in the related art that the solidification effect of grouting to reinforce the gravel aquifer to be excavated is not ideal and it is difficult to carry out tunneling construction in the gravel aquifer.

[0006] The present invention provides a tunnel excavation construction method, which includes: inserting an advance support steel pipe into the head working face along the tunnel contour line to obtain an advance support area located in front of the head working face; in the advance support area, moving the head working face forward by an excavation distance to obtain a tunnel section to be supported located behind the head working face; temporarily supporting the tunnel section to be supported to obtain a temporary support tunnel section; permanently supporting the temporary support tunnel section to obtain a permanent support tunnel section; and repeatedly executing the above tunnel excavation steps until the second water diversion ditch of the tunnel excavation is completed.

[0007] Furthermore, there are multiple first steel pipe support positions and multiple second steel pipe support positions on the head working face, and the multiple first steel pipe support positions and the multiple second steel pipe support positions are alternately arranged along the tunnel contour line. In two adjacent tunnel excavation steps, the advance support steel pipe is inserted into the first steel pipe support position and the second steel pipe support position respectively.

[0008] Furthermore, in the step of inserting the advance support steel pipe into the head working face along the tunnel contour line, a preset length of advance support steel pipe is reserved behind the head working face; in the step of moving the head working face forward by an excavation distance, the excavation distance is the preset length.

[0009] Furthermore, the steps of permanently supporting the temporary support tunnel section include: constructing a second water diversion ditch of the inverted bottom arch groove on the bottom plate of the temporary support tunnel section, pouring concrete into the inverted bottom arch groove to obtain an inverted bottom arch; supporting the arch wall formwork to form an arch wall interval between the top plate of the temporary support tunnel section and the arch wall formwork and between the side wall of the temporary support tunnel section and the arch wall formwork, pouring concrete in the arch wall interval to obtain the arch wall; after the arch wall reaches a preset strength, the arch wall formwork is removed.

[0010] Furthermore, after the step of constructing the inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section also includes: reserving a first casting notch and a first inclined surface at the upper end opening of the inverted bottom arch groove, the extension direction of the first casting notch is the same as the extension direction of the temporary support tunnel section, and the first inclined surface is inclined upward in the direction away from the first casting notch, so that after pouring concrete into the inverted bottom arch groove and obtaining the inverted bottom arch, a first water guide ditch extending in the same direction as the temporary support tunnel section is formed on the upper surface of the inverted bottom arch, and the upper surface of the inverted bottom arch gradually tilts upward in the direction away from the first water guide ditch.

[0011] Furthermore, the steps of temporarily supporting the tunnel section to be supported include: laying steel mesh and installing anchor rods on the top plate and side walls of the tunnel section to be supported; after completing the laying of the steel mesh and the installation of the anchor rods, setting water pipes on the side walls of the tunnel section to be supported; after completing the installation of the water pipes, spraying concrete on the top plate and side walls of the tunnel section to be supported.

[0012] Furthermore, the step of setting a water guide pipe on the side wall of the tunnel section to be supported includes: setting a water guide point on each of the two side walls of the tunnel section to be supported at every water guide distance along the extension direction of the tunnel section to be supported; setting a water guide pipe at the water guide point and inserting it into the gravel aquifer to a water guide depth, and the part of the water guide pipe located in the gravel aquifer has a seepage hole.

[0013] Furthermore, after the step of constructing an inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section also includes: reserving a second casting gap connected to the first casting gap at the upper end opening of the inverted bottom arch groove, the extension direction of the second casting gap is perpendicular to the extension direction of the temporary support tunnel section, and the two ends of the second casting gap respectively extend to the bottom of the two water pipes arranged opposite to each other on the two side walls of the tunnel to be supported, so that after pouring concrete into the inverted bottom arch groove and obtaining the inverted bottom arch, a second water guide ditch connected to the first water guide ditch is formed on the upper surface of the inverted bottom arch.

[0014] Furthermore, in the step of constructing the second water guide ditch of the inverted bottom arch groove on the bottom plate of the temporary support tunnel section, the front end of the inverted bottom arch groove is lagged behind the head working face by a construction lag distance; and / or, the construction depth of the inverted bottom arch groove is gradually increased in the direction away from the side wall of the tunnel section to be supported, and in each tunnel excavation step, the front end of the arch wall interval is flush with the front end of the inverted bottom arch groove, and the rear end of the arch wall interval is flush with the rear end of the inverted bottom arch groove.

[0015] Furthermore, after completing the laying of the steel mesh and the installation of the anchor rods, before the step of spraying concrete on the top plate and side walls of the tunnel section to be supported, the step of temporarily supporting the tunnel section to be supported also includes: erecting a steel shed between the tunnel section to be supported and the head working face, and connecting the advance support steel pipe to the steel shed.

[0016] Furthermore, the step of erecting a steel shed between the tunnel section to be supported and the head working face includes: erecting a steel arch frame between the top plate of the tunnel section to be supported and the head working face; constructing shed leg grooves between the two sides of the bottom plate of the tunnel section to be supported and the head working face, pouring concrete into the shed leg grooves to obtain shed leg base blocks; erecting and installing shed legs between the side walls of the tunnel section to be supported and the head working face, connecting the upper ends of the shed legs to the steel arch frame, and connecting the lower ends of the shed legs to the shed leg base blocks; verifying the position of the steel shed, and controlling the error between multiple steel sheds to be less than or equal to the position error parameter in multiple tunnel excavation steps.

[0017] Furthermore, in the step of erecting a steel shed between the tunnel section to be supported and the head-on working face, the steel shed is erected between the tunnel section to be supported and the head-on working face at a preset head-on angle.

[0018] Furthermore, the steps of laying steel mesh and installing anchor rods on the roof and side walls of the tunnel section to be supported include: laying steel mesh on the roof and side walls of the tunnel section to be supported, connecting the steel mesh and the advance support steel pipe; installing anchor rods between two adjacent steel meshes, connecting the two adjacent steel meshes; and applying pre-tightening force to the anchor rods.

[0019] Furthermore, in the step of installing anchor rods between two adjacent steel meshes: the lowest anchor rod is installed at a preset angle downward compared to the horizontal plane, and the remaining anchor rods are installed perpendicular to the inner wall of the tunnel section to be supported; and / or, one end of the anchor rod is connected to the stable rock layer outside the tunnel section to be supported, and the other end of the anchor rod is provided with a tray, and the tray abuts the inner wall of the tunnel section to be supported.

[0020] Furthermore, in the step of inserting the advance support steel pipe into the head working face along the tunnel contour line, the advance support steel pipe is inserted into the head working face at a preset external insertion angle, and the preset external insertion angle is the angle between the insertion direction of the advance support steel pipe and the excavation direction; and / or, after completing the tunnel excavation step, the tunnel excavation construction method also includes: monitoring the deformation of the tunnel.

[0021] By applying the technical solution of the present invention, an advance support steel pipe is inserted into the head working face along the excavation direction and slope of the tunnel, so that the front end of the advance support steel pipe is inserted into the gravel aquifer, and multiple advance support steel pipes arranged along the tunnel construction contour line and an advance support area located at the head working face are obtained. Therefore, in the advance support area, when the head working face is moved forward under the cover of the advance support steel pipe, the advance support effect of the advance support steel pipe is utilized to prevent the gravel aquifer from spalling, leaking or rheologically causing large-scale collapse under the action of its own weight. After obtaining the tunnel section to be supported located behind the head working face, the tunnel section to be supported is temporarily supported to obtain a temporary support tunnel section, thereby improving the compressive strength of the gravel aquifer outside the temporary support tunnel section, and avoiding the occurrence of accidents such as leaking or spalling of the tunnel section to be supported during construction. Permanent support is provided to the temporary support roadway section, resulting in a permanent support roadway section, which increases the deformation resistance of the permanent support roadway section. Therefore, in each tunnel excavation cycle, the combination of advance support, temporary support, and permanent support reduces the risk of roof leakage and wall spalling in the gravel aquifer under its own weight when excavating in the gravel aquifer using advance support. Temporary support improves the compressive strength of the gravel aquifer, reducing the risk of roof subsidence and side wall displacement in the temporary support roadway section. Permanent support increases the deformation resistance of the permanent support roadway section, thereby reinforcing the gravel aquifer to be excavated, reducing the construction difficulty, support difficulty, and construction cost, and improving the compressive and deformation resistance of the roadway obtained by excavation in the gravel aquifer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 A flow chart of a tunnel excavation construction method provided in an embodiment of the present invention is shown;

[0024] Figure 2 A cross-sectional view of a tunnel according to a tunnel excavation construction method provided by an embodiment of the present invention is shown;

[0025] Figure 3 A cross-sectional view of a tunnel according to another perspective of the tunnel excavation construction method provided by an embodiment of the present invention is shown;

[0026] Figure 4 A cross-sectional view of an advance support steel pipe in a tunnel excavation construction method according to an embodiment of the present invention is shown;

[0027] Figure 5 A schematic structural diagram of a steel shed in a tunnel excavation construction method according to an embodiment of the present invention is shown;

[0028] Figure 6 Shown Figure 5 A partial enlarged view of point A in the middle;

[0029] Figure 7 A cross-sectional view showing a steel arch frame, shed legs, and special clips of a steel shed in a tunnel excavation construction method provided according to an embodiment of the present invention;

[0030] Figure 8 A cross-sectional view of a steel shed leg of a tunnel excavation construction method according to an embodiment of the present invention is shown;

[0031] Figure 9 A cross-sectional view of a pipe clamp in a tunnel excavation construction method provided according to an embodiment of the present invention is shown.

[0032] The above drawings include the following reference numerals:

[0033] 10. Advance support steel pipe; 11. Pipe body; 12. Cone; 13. Pipe clamp;

[0034] 20. Heading working face; 21. First steel pipe support position; 22. Second steel pipe support position;

[0035] 31. Advanced support area; 32. Tunnel section to be supported;

[0036] 40. Inverted bottom arch; 41. First water diversion ditch;

[0037] 50. Wall;

[0038] 61. Steel mesh; 62. Anchor rod;

[0039] 70. Aqueduct;

[0040] 80. Steel shed; 81. Steel arch frame; 82. Shed leg base block; 83. Shed legs; 831. Limiting plate; 84. Special clip;

[0041] L, preset length;

[0042] α, preset angle. DETAILED DESCRIPTION

[0043] The following will be combined with the accompanying 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 embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] like Figures 1 to 9 As shown, an embodiment of the present invention provides a tunnel excavation construction method, which includes:

[0045] Insert the advance support steel pipe 10 into the head working face 20 along the roadway contour line to obtain an advance support area 31 located in front of the head working face 20;

[0046] In the advanced support area 31, the head working face 20 is moved forward by an excavation distance to obtain a roadway section 32 to be supported behind the head working face 20;

[0047] Perform temporary support on the roadway section 32 to be supported, and obtain a temporary support roadway section;

[0048] Carry out permanent support on the temporary support roadway section to obtain the permanent support roadway section;

[0049] The above tunnel excavation steps are repeated multiple times until the tunnel excavation is completed.

[0050] By applying the tunnel excavation construction method provided in this embodiment, the advance support steel pipe 10 is inserted into the head working face 20 along the excavation direction and slope of the tunnel, so that the front end of the advance support steel pipe 10 is inserted into the gravel aquifer, and multiple advance support steel pipes 10 arranged along the tunnel construction contour line and the advance support area 31 located at the head working face 20 are obtained. Therefore, in the advance support area 31, when the head working face 20 is moved forward under the cover of the advance support steel pipe 10, the advance support effect of the advance support steel pipe 10 is utilized to prevent the gravel aquifer from spalling, leaking or flowing under the action of its own weight, thereby preventing large-scale collapse. After obtaining the roadway section 32 to be supported behind the head working face 20, temporary support is provided to the roadway section 32 to obtain a temporary support roadway section. This improves the compressive strength of the gravel aquifer outside the temporary support roadway section, thereby preventing accidents such as roof collapse or wall spalling in the roadway section 32 to be supported during construction. The temporary support roadway section is then permanently supported to obtain a permanent support roadway section, thereby increasing the deformation resistance of the permanent support roadway section. Therefore, in each tunnel excavation step, advance support, temporary support and permanent support are combined. Advance support is used to reduce the risk of roof leakage and side wall collapse of the gravel aquifer under its own weight when excavating in the gravel aquifer. Temporary support is used to improve the compressive strength of the gravel aquifer, reducing the risk of roof subsidence and side wall displacement in the temporary support tunnel section. Permanent support is used to increase the deformation resistance of the permanent support tunnel section, thereby reinforcing the gravel aquifer to be excavated, reducing the construction difficulty, support difficulty and construction cost, and improving the compressive and deformation resistance of the tunnel obtained by excavating in the gravel aquifer.

[0051] It should be noted that roof leakage refers to the phenomenon that the roof rock of the tunnel falls off in the form of fragments or debris in a local area. Spalling refers to the phenomenon that the roof rock layer of the tunnel after excavation becomes suspended, which causes the pressure to be transferred to the side walls of the tunnel, forming a pressurized area on the side walls of the tunnel, causing the side walls of the tunnel to be crushed and squeezed into the space inside the tunnel, which has a great impact on the wellbore construction. The head working face 20 refers to the working face of tunnel mining or excavation. The wellbore water inflow refers to the amount of water flowing into the wellbore from the gravel aquifer per unit time during the excavation process.

[0052] In this embodiment, the tunnel excavation construction method can be applied to the construction of a return air inclined shaft, which refers to an inclined shaft for discharging polluted air.

[0053] In this embodiment, within the advanced support area 31, after the head working face 20 is advanced by a certain excavation distance, an excavator loader is used to excavate along the tunnel contour. Manual excavation with a pneumatic pick is performed in areas not easily accessible to the excavator, such as the tunnel's bottom corners and surrounding contours, to ensure that the tunnel dimensions meet the design requirements. It should be noted that a pneumatic pick is a handheld construction tool powered by compressed air, which uses the impact of compressed air to break hard objects.

[0054] like Figure 3 As shown, there are multiple first steel pipe support positions 21 and multiple second steel pipe support positions 22 on the head working face 20. The multiple first steel pipe support positions 21 and the multiple second steel pipe support positions 22 are alternately arranged along the roadway contour line. In two adjacent roadway excavation steps, the advance support steel pipe 10 is respectively inserted into the first steel pipe support position 21 and the second steel pipe support position 22. Since the multiple first steel pipe support positions 21 and the multiple second steel pipe support positions 22 are alternately arranged along the roadway contour line, in two adjacent roadway excavation steps, the advance support steel pipe 10 is respectively inserted into the first steel pipe support position 21 and the second steel pipe support position 22, so that the advance support steel pipe 10 is alternately inserted forward, which not only speeds up the construction speed but also ensures the construction safety.

[0055] like Figure 3 As shown, during the step of inserting the advance support steel pipe 10 into the head working face 20 along the tunnel contour, a preset length L of advance support steel pipe 10 is reserved behind the head working face 20. This facilitates fixing the advance support steel pipe 10 behind the head working face 20 during excavation, thereby improving the reliability of the advance support function of the advance support steel pipe 10.

[0056] like Figure 4 As shown, the advance support steel pipe 10 includes a pipe body 11 and a cone 12 arranged at one end of the pipe body 11. The cone 12 facilitates the insertion of the advance support steel pipe 10 into the gravel aquifer and prevents gravel from entering the advance support steel pipe 10.

[0057] In this embodiment, the length of the advance support steel pipe 10 is 3 times the preset length L, the diameter of the advance support steel pipe 10 is 50 mm, the length of the tube body 11 is 3000 mm, the length of the vertebral body 12 is 500 mm, the spacing between adjacent first steel pipe support positions 21 and second steel pipe support positions 22 is 400 mm, and the number of first steel pipe support positions 21 and the number of second steel pipe support positions 22 are both 13.

[0058] like Figure 3As shown, in the step of moving the head working face 20 forward by an excavation distance, the excavation distance is a preset length L. Thus, an advance support steel pipe 10 of the preset length L is reserved behind the head working face 20, so as to facilitate fixing the advance support steel pipe 10 behind the head working face 20 and ensure that the length of the advance support area 31 meets the advance support requirements in the process of moving the head working face 20 forward by an excavation distance.

[0059] In this embodiment, the excavation distance and the preset length L are both 1000 mm.

[0060] like Figure 2 As shown in the figure, the steps for permanent support of the temporary support roadway section include:

[0061] Construct an inverted arch groove on the bottom plate of the temporary support tunnel section, pour concrete into the inverted arch groove to obtain an inverted arch 40;

[0062] Supporting the arch wall formwork, forming the arch wall intervals between the top plate of the temporary support tunnel section and the arch wall formwork and between the side walls of the temporary support tunnel section and the arch wall formwork, pouring concrete in the arch wall intervals to obtain the arch wall 50;

[0063] After the arch wall 50 reaches the preset strength, the arch wall formwork is removed. By constructing an inverted arch groove on the floor of the temporary support tunnel section and pouring concrete into the inverted arch groove, an inverted arch 40 is obtained. When the inverted arch 40 reaches the preset strength, the arch wall formwork is installed and concrete is poured in the arch wall interval to obtain the arch wall 50. After the arch wall 50 reaches the preset strength, the arch wall formwork is removed. The inverted arch 40 and arch wall 50 are then used to permanently support the roof, floor, and side walls of the temporary support tunnel section, thereby increasing the deformation resistance of the permanent support tunnel section.

[0064] In this embodiment, a waterproofing agent is added to the concrete used to cast the anti-bottom arch groove and the arch wall separation. The amount of waterproofing agent used is 8% of the amount of cement in the concrete. The waterproofing agent is BR-3 type waterproofing agent. The strength of the waterproofing agent is not less than C30, and the anti-seepage grade of the waterproofing agent is not less than S8.

[0065] In this embodiment, a pump is used to pour concrete into the interval between the anti-bottom arch groove and the arch wall, and a vibrating rod is used to vibrate the concrete to prevent honeycombing.

[0066] Furthermore, in this embodiment, the arch wall 50 and the inverted bottom arch 40 are cast into a whole, so that the permanent support body is subjected to full-circle axial stress, thereby improving the compressive and deformation resistance of the tunnel obtained by excavation in the gravel aquifer.

[0067] like Figure 2As shown, after the step of constructing the inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section also includes:

[0068] A first casting notch and a first inclined surface are reserved at the upper end opening of the inverted bottom arch trough. The extending direction of the first casting notch is the same as the extending direction of the temporary support tunnel section. The first inclined surface is inclined upward in a direction away from the first casting notch, so that after concrete is poured into the inverted bottom arch trough and the inverted bottom arch 40 is obtained, a first water guide ditch 41 extending in the same direction as the temporary support tunnel section is formed on the upper surface of the inverted bottom arch 40, and the upper surface of the inverted bottom arch 40 gradually tilts upward in a direction away from the first water guide ditch 41. By adopting the above steps, after concrete is poured into the inverted bottom arch trough and the inverted bottom arch 40 is obtained, a first water guide ditch 41 extending in the same direction as the temporary support tunnel section can be formed on the upper surface of the inverted bottom arch 40, so that the upper surface of the inverted bottom arch 40 gradually tilts upward in a direction away from the first water guide ditch 41, so that water in the tunnel flows into the first water guide ditch 41 along the upper surface of the inverted bottom arch 40, making the tunnel floor clean and tidy, and the collected water is drained out by the first water guide ditch 41.

[0069] In this embodiment, the width of the cross section of the first water diverter 41 obtained by cutting a plane perpendicular to the extension direction of the temporary support tunnel section is 100 mm, the height of the cross section of the first water diverter 41 obtained by cutting a plane perpendicular to the extension direction of the temporary support tunnel section is 100 mm, and the angle between the upper surface of the anti-bottom arch 40 and the horizontal plane is 5°.

[0070] like Figure 2 As shown, the steps of temporarily supporting the roadway section 32 to be supported include:

[0071] Lay steel mesh 61 and install anchor rods 62 on the roof and side walls of the tunnel section 32 to be supported;

[0072] After the steel mesh 61 is laid and the anchor rods 62 are installed, a water pipe 70 is installed on the side of the tunnel section 32 to be supported;

[0073] After the installation of the water conduit 70, concrete is sprayed onto the roof and side walls of the tunnel section 32 to be supported. By laying steel mesh 61 and installing anchor rods 62 on the roof and side walls of the tunnel section 32 to be supported, the surrounding rock can be flexibly deformed, effectively preventing cracking. Spraying concrete onto the roof and side walls of the tunnel section 32 to be supported improves the compressive strength of the gravel aquifer outside the temporary support tunnel section, preventing accidents such as roof leakage or wall spalling in the tunnel section 32 to be supported during construction. Furthermore, the installation of the water conduit 70 allows water from the gravel aquifer outside the tunnel to be drawn into the tunnel and drained away, thereby reducing tunnel pressure. Spraying concrete onto the roof and side walls of the tunnel section 32 to be supported reduces rock fragments from falling from the roof and side walls, and concrete can fill gaps left by fallen rock fragments during excavation, ensuring subsequent construction safety.

[0074] In this embodiment, concrete is sprayed on the top plate and side walls of the supporting tunnel section 32. The spraying thickness of the concrete is 50 mm. A waterproofing agent is added to the sprayed concrete. The amount of the waterproofing agent is 8% of the amount of cement in the concrete. The waterproofing agent is BR-3 type waterproofing agent. The strength of the waterproofing agent is not less than C30, and the anti-seepage grade of the waterproofing agent is not less than S8.

[0075] like Figure 2 As shown, the steps of setting the water pipe 70 on the side wall of the tunnel section 32 to be supported include:

[0076] A water guide point is set on each side of the tunnel section 32 to be supported at every water guide distance along the extension direction of the tunnel section to be supported;

[0077] At the water diversion point, a water conduit 70 is installed, inserted into the gravel aquifer to a certain depth. The portion of the water conduit 70 located within the gravel aquifer has seepage holes. Water from the gravel aquifer outside the roadway enters the water conduit 70 through the seepage holes and is then discharged through the water conduit 70. Since water conduits are installed on both sides of the supported roadway section 32 at intervals along its extension, the drainage of water from the gravel aquifer outside the roadway is improved, further reducing roadway pressure.

[0078] In this embodiment, the water guide distance is 20m and the water guide depth is 500mm.

[0079] In this embodiment, after the step of constructing the inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section further includes:

[0080] A second casting notch connected to the first casting notch is reserved at the upper opening of the reverse bottom arch trough, the extension direction of the second casting notch being perpendicular to the extension direction of the temporary support tunnel section, and the two ends of the second casting notch respectively extend to the bottom of the two water pipes 70 arranged opposite to each other on the two side walls of the tunnel section to be supported, so that after concrete is poured into the reverse bottom arch trough and the reverse bottom arch 40 is obtained, a second water guide ditch connected to the first water guide ditch 41 is formed on the upper surface of the reverse bottom arch 40. By adopting the above steps, after concrete is poured into the reverse bottom arch trough and the reverse bottom arch 40 is obtained, a second water guide ditch connected to the first water guide ditch 41 is formed on the upper surface of the reverse bottom arch 40, and the two ends of the second water guide ditch respectively extend to the bottom of the two water pipes 70 arranged opposite to each other on the two side walls of the tunnel section to be supported, so that water discharged from the water pipes 70 flows into the first water guide ditch 41 through the second water guide ditch and is discharged.

[0081] In this embodiment, the width of the cross section of the second water channel taken along a plane perpendicular to the extension direction of the second water channel is 50 mm, and the height of the cross section of the second water channel taken along a plane perpendicular to the extension direction of the second water channel is 50 mm. The spacing between two adjacent second water channels is 20 m.

[0082] In this embodiment, during the step of constructing the inverted bottom arch groove on the floor of the temporary support tunnel section, the front end of the inverted bottom arch groove is delayed by a construction delay distance of 20° from the head working surface 20°. Since the front end of the inverted bottom arch groove is delayed by a construction delay distance of 20° from the head working surface 20°, the insertion of the advance support steel pipe 10 in the next tunnel excavation step can be carried out simultaneously with the pouring of concrete into the inverted bottom arch groove in the current tunnel excavation step, thereby speeding up the construction progress and avoiding interference between the various processes.

[0083] In this embodiment, the construction delay distance is 10m.

[0084] like Figure 2 As shown, the construction depth of the inverted bottom arch groove gradually increases in the direction away from the side of the roadway section 32 to be supported. In each roadway excavation step, the front end of the arch wall interval is flush with the front end of the inverted bottom arch groove, and the rear end of the arch wall interval is flush with the rear end of the inverted bottom arch groove. Since the construction depth of the inverted bottom arch groove gradually increases in the direction away from the side of the roadway section 32 to be supported, specifically, by intercepting the bottom wall of the inverted bottom arch groove with a plane perpendicular to the extension direction of the temporary support roadway section, a downwardly convex arc can be obtained, which facilitates the force of the permanent support formed by the inverted bottom arch 40 and the arch wall 50 to tend to be circular, reducing the force on the roadway in the direction perpendicular to its inner wall, and increasing the roadway's ability to resist deformation. The lengths of the inverted bottom arch 40 and the arch wall 50 obtained in each roadway excavation step are the same.

[0085] In this embodiment, the construction width of the inverted bottom arch groove is consistent with the width of the tunnel, the construction depth of the inverted bottom arch groove at both ends of its construction width is 400 mm, and the construction depth of the inverted bottom arch groove in the middle of its construction width is 700 mm.

[0086] like Figure 2 As shown, after the steel mesh 61 is laid and the anchor rods 62 are installed, and before the step of spraying concrete on the roof and side walls of the tunnel section 32 to be supported, the step of temporarily supporting the tunnel section 32 to be supported further includes:

[0087] A steel shed 80 is erected between the roadway section 32 to be supported and the head working face 20 to connect the advance support steel pipe 10 and the steel shed 80. By erecting the steel shed 80 between the roadway section 32 to be supported and the head working face 20 to connect the advance support steel pipe 10 and the steel shed 80, there is no need to additionally fix the steel shed 80 and the stability of the advance support steel pipe 10 is improved.

[0088] In this embodiment, the pipe clamp 13 is used to connect the advance support steel pipe 10 and the steel shed 80 .

[0089] Moreover, after spraying concrete on the top plate and side walls of the supporting tunnel section 32 and pouring the anti-bottom arch groove and the arch wall interval, the steel mesh, anchor rods, steel shed, advance support steel pipe 10, anti-bottom arch 40 and arch wall 50 can become an integrated structure, coordinate with each other and bear the load together.

[0090] When the advance support steel pipe 10 is inserted into the head working face 20, the advance support steel pipe 10 is connected to the two steel sheds 80 behind the head working face 20. With the subsequent excavation and erection of steel sheds, each advance support steel pipe 10 is eventually connected to four steel sheds 80, increasing the deformation resistance of the steel sheds 80 and the advance support steel pipe 10.

[0091] like Figure 2 As shown, the steps of erecting the steel shed 80 between the roadway section to be supported 32 and the head working face 20 include:

[0092] A steel arch 81 is erected between the roof of the tunnel section 32 to be supported and the head working face 20;

[0093] Construct leg grooves between the two sides of the floor of the tunnel section 32 to be supported and the head working face 20, and pour concrete into the leg grooves to obtain leg foundation blocks 82;

[0094] Install the scaffolding legs 83 between the side walls of the tunnel section 32 to be supported and the head working face 20, connect the upper ends of the scaffolding legs 83 to the steel arch 81, and connect the lower ends of the scaffolding legs 83 to the scaffolding leg base blocks 82;

[0095] The position of the steel shed 80 was verified, and during multiple tunneling steps, the deviation between the multiple steel sheds 80 was controlled to be less than or equal to the position error parameter. A single hydraulic strut was used to assist in the installation of the steel arch 81. Concrete was poured into the shed leg grooves to obtain the shed leg base blocks 82 that served as the foundation of the steel shed 80.

[0096] It should be noted that controlling the offset between multiple steel sheds 80 to be less than or equal to the position error parameter means that multiple steel sheds 80 are arranged in the front-to-back direction, and the up-down offset and left-right offset between the multiple steel sheds 80 are less than or equal to the position error parameter.

[0097] In this embodiment, the width of the shed leg base block 82 is 400 mm, the length of the shed leg base block 82 is 400 mm, the height of the shed leg base block 82 is 300 mm, and the position error parameter is 50 mm.

[0098] Specifically, the upper end of the shed leg 83 is buckled on the side of the steel arch frame 81 away from the head-on working surface, and the lower end of the steel arch frame 81 is placed on the limit plate 831 on the inner side of the shed leg 83. The steel arch frame 81 and the shed leg 83 are connected by special clips 84 every 500 mm.

[0099] In this embodiment, in the step of erecting the steel shed 80 between the roadway section to be supported 32 and the head-on working face 20, the steel shed 80 is erected between the roadway section to be supported 32 and the head-on working face 20 at a preset face-on angle. It should be noted that the preset face-on angle refers to the angle between the vertical line between the roof and the floor of the roadway to be supported and the steel shed 80. Erecting the steel shed 80 between the roadway section to be supported 32 and the head-on working face 20 at the preset face-on angle can overcome the downward thrust on the steel shed 80 and prevent the steel shed 80 from tipping over.

[0100] In this embodiment, the steps of laying the steel mesh 61 and installing the anchor rods 62 on the roof and side walls of the tunnel section 32 to be supported include:

[0101] Lay a steel mesh 61 on the roof and side walls of the tunnel section 32 to be supported, and connect the steel mesh 61 and the advance support steel pipe 10;

[0102] An anchor rod 62 is installed between two adjacent steel meshes 61 to connect the two adjacent steel meshes 61;

[0103] Applying pre-tightening force to the anchor rod 62. By connecting the steel mesh 61 and the advance support steel pipe 10, connecting two adjacent steel meshes 61 and anchor rods 62, and applying pre-tightening force to the anchor rods 62, the support effect of the steel mesh 61 and anchor rods 62 on the supported tunnel section 32 can be improved.

[0104] In this embodiment, the length of the steel mesh 61 along the tunnel contour line is 5100 mm, and the length of the steel mesh 61 along the extension direction of the tunnel section 32 to be supported is 900 mm. The steel mesh 61 is made of cross-welded steel bars with a diameter of 6.5 mm. The length and width of the mesh of the steel mesh 61 are both 100 mm. Double-strand 8# iron wire is used to connect the advance support steel pipe 10 and the steel mesh 61. In the extension direction of the advance support steel pipe 10, the steel mesh 61 is connected to the advance support steel pipe every 450 mm, that is, it is fixed on both sides and in the middle of the steel mesh 61. The anchor rod 62 is a threaded steel anchor rod, and the diameter of the anchor rod 62 is 20 mm.

[0105] In this embodiment, when a pre-tightening force is applied to the anchor rod 62 , the applied torque is not less than 100 N·m, and the applied pull-out force is not less than 70 kN.

[0106] like Figure 2 As shown, in the step of installing the anchor rod 62 between two adjacent steel meshes 61:

[0107] The lowest anchor rod 62 is installed at a preset angle α downwardly compared to the horizontal plane, and the remaining anchor rods 62 are installed perpendicular to the inner wall of the tunnel section to be supported 32. Installing the lowest anchor rod 62 at a preset angle α downwardly compared to the horizontal plane can prevent the lowest anchor rod 62 from being damaged.

[0108] It should be noted that, in this embodiment, the lowest anchor rod 62 refers to the lowest anchor rod 62 in a row of anchor rods 62 installed between two adjacent steel meshes 61 .

[0109] In this embodiment, the preset angle α is 10°.

[0110] In this embodiment, in the step of installing the anchor rod 62 between two adjacent steel meshes 61:

[0111] One end of the anchor rod 62 is connected to the stable rock formation outside the roadway section 32 to be supported, and the other end of the anchor rod 62 is provided with a tray, which abuts the inner wall of the roadway section 32 to be supported. Because one end of the anchor rod 62 is connected to the stable rock formation outside the roadway section 32 to be supported and the other end of the anchor rod 62 is provided with a tray abutting the inner wall of the roadway section 32 to be supported, the anchor rod 62 reinforces the gravel aquifer and the stable surrounding rock into a whole, improving the overall stability and deformation resistance of the roadway section 32 to be supported, and curbing the subsidence of the roof and displacement of the two sides after the roadway support is implemented.

[0112] Specifically, after the steel mesh 61 is laid, a pallet is pressed against the side of the steel mesh 61 away from the roadway section 32 to be supported, and then anchor rods 62 are installed. The length of the anchor rods 62 is determined by the distance between the inner wall of the roadway section 32 to be supported and the stable rock formation outside the roadway section 32 to be supported. The pallet is a W-shaped iron pallet with a size of 300×275×5mm.

[0113] In this embodiment, the length of the anchor rod 62 is between 1000 mm and 3000 mm, and each anchor rod 62 is anchored by two sections of MSK2370 resin rolls. The distance between two adjacent anchor rods 62 along the extension direction of the tunnel section 32 to be supported is 800 mm, and the distance between two adjacent anchor rods 62 along the extension direction of the tunnel section 32 to be supported is 1000 mm.

[0114] In this embodiment, during the step of inserting the advance support steel pipe 10 into the head working face 20 along the roadway contour, the advance support steel pipe 10 is inserted into the head working face 20 at a preset external insertion angle, which is the angle between the insertion direction of the advance support steel pipe 10 and the excavation direction. Inserting the advance support steel pipe 10 into the head working face 20 at the preset external insertion angle facilitates resistance to pressure exerted by the rock formation outside the roadway directed toward the inside of the roadway.

[0115] The preset external interpolation angle ranges from 0° to 2°.

[0116] In this embodiment, after completing the tunnel excavation step, the tunnel excavation construction method further includes monitoring the deformation of the tunnel. Specifically, detection points are set at intervals along the tunnel's extension direction. A cross detection system is configured at each detection point. The cross detection system emits two first rays and two second rays. The two first rays are emitted in reverse to the tunnel's roof and floor, while the two second rays are emitted in reverse to the tunnel's side walls. Monitoring shows that the deformation between the tunnel's roof and floor, and between the two side walls, does not exceed 100 mm, fully meeting the maximum deformation of 50 mm required for safe production.

[0117] The method provided in this embodiment is applied, and the following construction steps are involved: inserting the advance support steel pipe 10 into the head working face 20 along the excavation direction and slope of the tunnel so that the front end of the advance support steel pipe 10 is inserted into the gravel aquifer, and connecting the advance support steel pipe 10 to the steel shed 80 installed in the previous cycle. Under the cover of the advance support steel pipe 10, the head working face 20 is moved forward to obtain the tunnel section 32 to be supported behind the head working face 20, laying a steel mesh 61 on the top plate and side walls of the tunnel section 32 to be supported, connecting the steel mesh 61 and the advance support steel pipe 10, installing anchor rods 62 between two adjacent steel meshes 61, connecting two adjacent steel meshes 61, setting a water guide pipe 70 on the side walls of the tunnel section 32 to be supported, spraying concrete on the top plate and side walls of the tunnel section 32 to be supported, and then A steel shed 80 is erected between the protection tunnel section 32 and the head working face 20, the advance support steel pipe 10 is connected to the steel shed 80, an anti-bottom arch groove is constructed on the bottom plate of the temporary support tunnel section, concrete is poured into the anti-bottom arch groove to obtain an anti-bottom arch 40, a arch wall formwork is supported, and an arch wall interval is formed between the top plate of the temporary support tunnel section and the arch wall formwork and between the side wall of the temporary support tunnel section and the arch wall formwork, concrete is poured in the arch wall interval to obtain the arch wall 50, and the arch wall 50 and the anti-bottom arch 40 are cast into a whole.

[0118] The installation of the advance support steel pipe 10 of the next cycle, the installation of the steel shed 80 of the current cycle, the installation of the anchor rod 62 and the pouring of concrete in the anti-bottom arch groove can be carried out simultaneously.

[0119] Applying the method provided in this embodiment has the following beneficial effects:

[0120] (1) In each tunnel excavation step, advance support, temporary support and permanent support are combined. When excavating in a gravel aquifer, advance support is used to reduce the risk of roof leakage and side wall collapse of the gravel aquifer under its own weight. Temporary support is used to improve the compressive strength of the gravel aquifer, reducing the risk of roof subsidence and side wall displacement in the temporary support tunnel section. Permanent support is used to increase the deformation resistance of the permanent support tunnel section, thereby reinforcing the gravel aquifer to be excavated, reducing the construction difficulty, support difficulty and construction cost, and improving the compressive strength and deformation resistance of the tunnel obtained by excavation in the gravel aquifer.

[0121] (2) Temporary support of steel mesh 61 and anchor rods 62 is used as active support to prevent deformation of the roadway, and permanent support of steel shed 80, anti-bottom arch 40 and arch wall 50 is used as passive support to prevent deformation of the roadway. Active support and passive support interact and coordinate support, with high support strength, which can effectively resist the bias creep deformation caused by gravity operation of gravel aquifer, greatly reduce the risk of collapse, and save construction costs;

[0122] (3) The arch wall 50 and the anti-bottom arch 40 are arranged in a ring, so that the permanent support body is subjected to full-circle axial force, thereby improving the compressive and deformation resistance of the tunnel obtained by excavation in the gravel aquifer;

[0123] (4) A water conduit 70 is provided to guide water from the gravel aquifer outside the tunnel into the tunnel and discharge it, thereby reducing the pressure in the tunnel. Spraying concrete on the roof and side walls of the supporting tunnel section 32 can reduce the amount of rock blocks falling from the roof and side walls, and concrete can be used to fill the gaps left by the rock blocks falling during the excavation process, thereby ensuring the safety of subsequent construction.

[0124] (5) A first water guide ditch 41 is formed on the upper surface of the inverted bottom arch 40 and extends in the same direction as the temporary support tunnel section, so that the upper surface of the inverted bottom arch 40 gradually tilts upward in a direction away from the first water guide ditch 41, so that the water in the tunnel flows into the first water guide ditch 41 along the upper surface of the inverted bottom arch 40, making the tunnel floor clean and tidy, and the collected water is discharged by using the first water guide ditch 41.

[0125] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0126] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0127] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0128] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0129] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0130] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A tunnel excavation construction method, characterized in that: The tunnel excavation construction method comprises: Inserting an advance support steel pipe (10) into the head working face (20) along the roadway contour line to obtain an advance support area (31) located in front of the head working face (20); In the advanced support area (31), the head working face (20) is moved forward by an excavation distance to obtain a roadway section (32) to be supported located behind the head working face (20); Temporarily supporting the tunnel section (32) to be supported to obtain a temporarily supported tunnel section; Performing permanent support on the temporary support roadway section to obtain a permanent support roadway section; Repeat the above tunnel excavation steps several times until the tunnel excavation is completed; The steps of temporarily supporting the tunnel section (32) to be supported include: laying a steel mesh (61) and installing anchor rods (62) on the roof and side walls of the tunnel section (32) to be supported; after the laying of the steel mesh (61) and the installation of the anchor rods (62) are completed, setting a water guide pipe (70) on the side walls of the tunnel section (32) to be supported; after the installation of the water guide pipe (70) is completed, spraying concrete on the roof and side walls of the tunnel section (32) to be supported; After the laying of the steel mesh (61) and the installation of the anchor rods (62), before the step of spraying concrete on the roof and side walls of the tunnel section (32) to be supported, the step of temporarily supporting the tunnel section (32) to be supported further includes: erecting a steel shed (80) between the tunnel section (32) to be supported and the head working face (20), connecting the advance support steel pipe (10) and the steel shed (80); erecting a steel arch frame (81) between the roof of the tunnel section (32) to be supported and the head working face (20); A leg trough is constructed between the two sides of the bottom plate and the head working surface (20), and concrete is poured into the leg trough to obtain a leg base block (82); a leg trough (83) is erected and installed between the side wall of the roadway section (32) to be supported and the head working surface (20), the upper end of the leg trough (83) is connected to the steel arch frame (81), and the lower end of the leg trough (83) is connected to the leg base block (82); the position of the steel trough (80) is checked, and in multiple steps of the roadway excavation, the error between the multiple steel troughs (80) is controlled to be less than or equal to the position error parameter.

2. The tunnel excavation construction method according to claim 1, characterized in that: A plurality of first steel pipe support positions (21) and a plurality of second steel pipe support positions (22) are provided on the head working face (20), wherein the plurality of first steel pipe support positions (21) and the plurality of second steel pipe support positions (22) are alternately arranged along the tunnel contour line, and in two adjacent tunnel excavation steps, the advance support steel pipe (10) is respectively inserted into the first steel pipe support position (21) and the second steel pipe support position (22).

3. The tunnel excavation construction method according to claim 1, characterized in that: In the step of inserting the advance support steel pipe (10) into the head working face (20) along the roadway contour line, a preset length of the advance support steel pipe (10) is reserved behind the head working face (20); In the step of moving the facing working face (20) forward by the excavation distance, the excavation distance is the preset length.

4. The tunnel excavation construction method according to claim 1, characterized in that: The steps of permanently supporting the temporary support roadway section include: Constructing an inverted bottom arch groove on the bottom plate of the temporary support tunnel section, and pouring concrete into the inverted bottom arch groove to obtain an inverted bottom arch (40); Supporting a truncated wall formwork, forming a truncated wall interval between the top plate of the temporary supporting tunnel section and the truncated wall formwork and between the side walls of the temporary supporting tunnel section and the truncated wall formwork, and pouring concrete in the truncated wall interval to obtain a truncated wall (50); After the arch wall (50) reaches a preset strength, the arch wall template is removed.

5. The tunnel excavation construction method according to claim 4, characterized in that: After the step of constructing the inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section further includes: A first pouring notch and a first inclined surface are reserved at the upper end opening of the reverse bottom arch groove, the extension direction of the first pouring notch is the same as the extension direction of the temporary support tunnel section, and the first inclined surface is inclined upward in a direction away from the first pouring notch, so that after concrete is poured into the reverse bottom arch groove and the reverse bottom arch (40) is obtained, a first water guide ditch (41) extending in the same direction as the temporary support tunnel section is formed on the upper surface of the reverse bottom arch (40), and the upper surface of the reverse bottom arch (40) gradually tilts upward in a direction away from the first water guide ditch (41).

6. The tunnel excavation construction method according to claim 5, characterized in that: The step of arranging the water guide pipe (70) on the side wall of the tunnel section (32) to be supported comprises: A water guide point is respectively provided on the two side walls of the tunnel section (32) to be supported at intervals of a water guide distance along the extension direction of the tunnel section (32) to be supported; The water guide pipe (70) is arranged at the water guide point and is inserted into the gravel aquifer to a water guide depth. The portion of the water guide pipe (70) located in the gravel aquifer is provided with a water seepage hole.

7. The tunnel excavation construction method according to claim 6, characterized in that: After the step of constructing the inverted bottom arch groove on the bottom plate of the temporary support tunnel section and before the step of pouring concrete into the inverted bottom arch groove, the step of permanently supporting the temporary support tunnel section further includes: A second casting notch is reserved at the upper end opening of the reverse bottom arch groove and is connected to the first casting notch. The extension direction of the second casting notch is perpendicular to the extension direction of the temporary support tunnel section. Both ends of the second casting notch extend to below the two water guide pipes (70) arranged opposite to each other on the two side walls of the tunnel section (32) to be supported, so that after concrete is poured into the reverse bottom arch groove and the reverse bottom arch (40) is obtained, a second water guide ditch connected to the first water guide ditch (41) is formed on the upper surface of the reverse bottom arch (40).

8. The tunnel excavation construction method according to any one of claims 4 to 7, characterized in that: In the step of constructing the reverse bottom arch groove on the bottom plate of the temporary support tunnel section, the front end of the reverse bottom arch groove is lagged behind the head working face (20) by a construction lag distance; and / or, The construction depth of the reverse bottom arch groove gradually increases in the direction away from the side wall of the tunnel section (32) to be supported. In each tunnel excavation step, the front end of the arch wall interval is flush with the front end of the reverse bottom arch groove, and the rear end of the arch wall interval is flush with the rear end of the reverse bottom arch groove.

9. The tunnel excavation construction method according to claim 6 or 7, characterized in that: In the step of erecting the steel shed (80) between the tunnel section to be supported (32) and the head working face (20), the steel shed (80) is erected between the tunnel section to be supported (32) and the head working face (20) at a preset head-on angle.

10. The tunnel excavation construction method according to claim 6 or 7, characterized in that: The steps of laying the steel mesh (61) and installing the anchor rods (62) on the roof and side walls of the tunnel section (32) to be supported include: Laying the steel mesh (61) on the roof and side walls of the tunnel section (32) to be supported, and connecting the steel mesh (61) and the advance support steel pipe (10); Installing the anchor rod (62) between two adjacent steel meshes (61) to connect the two adjacent steel meshes (61); A pre-tightening force is applied to the anchor rod (62).

11. The tunnel excavation construction method according to claim 10, characterized in that: In the step of installing the anchor rod (62) between two adjacent steel meshes (61): The lowest anchor rod (62) is installed at a preset angle downwardly tilted relative to the horizontal plane, and the remaining anchor rods (62) are installed perpendicularly to the inner wall of the tunnel section (32) to be supported; and / or, One end of the anchor rod (62) is connected to the stable rock layer outside the tunnel section (32) to be supported, and the other end of the anchor rod (62) is provided with a tray, and the tray abuts against the inner wall of the tunnel section (32) to be supported.

12. The tunnel excavation construction method according to any one of claims 1 to 7, characterized in that: In the step of inserting the advance support steel pipe (10) into the head working face (20) along the tunnel contour line, the advance support steel pipe (10) is inserted into the head working face (20) at a preset external insertion angle, wherein the preset external insertion angle is the angle between the insertion direction of the advance support steel pipe (10) and the excavation direction; and / or, After completing the tunnel excavation step, the tunnel excavation construction method further includes: monitoring the deformation of the tunnel.

Images