Prevention and treatment method for deformation of primary support in water-rich area of tunnel

Abstract

The invention discloses a tunnel water-rich area primary support deformation prevention and control method. The method comprises primary support monitoring measurement and section measurement, wherein a set of monitoring measurement points are arranged on the section at equal intervals, monitoring points are arranged on an arch crown and haunches on the left side and the right side, a total station is adopted for conducting encryption measurement on a deformation invasion limit section without a prism, and the temporary support and grouting reinforcement range is determined. According to the method for preventing and treating deformation of the primary support in the water-rich area of the tunnel, a temporary steel arch support is additionally arranged, so that a ring can be quickly closed under the condition that an inverted arch cannot be constructed, further expansion of deformation is effectively prevented, the safety coefficient in the tunnel construction treatment period is improved, and a soil body behind the primary support is solidified through cement-water glass double-liquid grouting; fractures of the tunnel surrounding rocks in the rainy season are quickly blocked, the influence of crack water in the surrounding rocks is effectively reduced, and a drainage system in the tunnel construction process is supplemented and perfected through the structure that a drainage pipe and a drainage pipe are newly added by grooving the contour lines between the primary support steel arches.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel protection, and in particular to a method for preventing and controlling deformation of primary branches in a water-rich area of a tunnel. Background Art

[0002] Current tunnel construction focuses on drainage after primary support installation. The drawings provide a comprehensive design for the drainage structure between the primary support and the secondary lining. However, temporary drainage during construction is not addressed. For example, blocking measures, such as anchor grouting, are primarily used from excavation until the secondary lining is poured. In the event of sudden heavy rainfall and high groundwater levels, the tunnel's water volume rapidly increases due to cracks and interlayers. This increases the earth pressure behind the primary support, irregularly compressing the steel arch frame and causing deformation, cracking, water seepage, and even collapse of the primary support.

[0003] At present, the treatment measures for this situation are often relatively simple, and the seepage phenomenon cannot be treated by combining drainage and blocking. The surrounding rock behind the initial support is still not self-stabilizing. When the arch is replaced, no temporary invert arch is set as support, which lacks safety.

[0004] The invention with Chinese patent publication number CN202211535879.0 discloses a deformation control device for the initial support of a large-span tunnel in a water-rich and soft area. However, in this invention, only water seepage through geotextiles is used to remove moisture from the surrounding rock, which has a low efficiency in removing water from the fissures inside the surrounding rock, and the surrounding rock is not reinforced by double-liquid grouting.

[0005] The invention with Chinese patent publication number CN202021598423.5 discloses a temporary arch protection structure in the arch replacement construction of the intersection section of a soft rock tunnel. However, the invention is limited to mechanical support for sections with weak surrounding rock, and ignores the impact of drainage, grouting and other processes on the stability of the surrounding rock.

[0006] The invention with Chinese patent publication number CN202221129447.5 discloses a temporary tunnel support device and a temporary tunnel support assembly, but the structure of the invention is relatively simple, and it is difficult to ensure the stability of the surrounding rock and prevent collapse during actual implementation. At the same time, the patent is mainly aimed at arch replacement construction in special areas such as the main intersection section of the tunnel, and its universality is not strong.

[0007] Therefore, it is of great significance to develop a safe, efficient and economical method for deformation treatment and prevention. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the present invention provides a method for preventing and controlling deformation of primary branches in water-rich areas of tunnels, which solves the problems raised in the above-mentioned background technology.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preventing and controlling deformation of primary branches in water-rich areas of tunnels, comprising the following steps:

[0010] S100, Initial support monitoring and cross-section measurement: A set of monitoring points will be arranged every 5 meters, with one monitoring point each at the arch crown and the left and right haunches. A total station without a prism will be used to conduct 1-2 meter interval measurements of the deformation-limited sections to determine the scope of temporary support and grouting reinforcement.

[0011] S200, temporary support and inverted arch closure: Use I18 I-beams to weld the left and right primary I-beams into a closed loop, add I18 I-beam diagonal braces at the deformed arch waist, cast a 30cm thick C25 concrete temporary inverted arch, and set up a temporary drainage ditch.

[0012] S300, Drilling drainage and water diversion: small pipes with a diameter of 424mm are driven into the seepage location, spaced 5 meters apart. A water trough is set at the bottom to drain the water to the collection pit, and the drainage hole also serves as a grouting pipe;

[0013] S400, anchor grouting consolidation: Use a 424mm diameter grouting tube for radial grouting, arranged in a 1.2m×1.2m plum blossom pattern, using a mixture of cement slurry with a water-cement ratio of 1:1 and 38°Bé water glass at a volume ratio of 1:0.6. Grouting pressure is 2-2.5MPa, maintained for 10 minutes, and the grouting range extends 3m circumferentially and 0.6m longitudinally.

[0014] S500, Replacement of Steel Arch: Install a small locking duct 0.5m above the intrusion limit steel arch and inject grout. Use I18 I-beams to install a second temporary diagonal brace. Use a jackhammer to chisel away the intrusion limit, then remove the steel arch. Re-weld or install a new I18 I-beam using connecting steel plates. Install system anchors according to the design.

[0015] S600, temporary support removal: After the initial support strength reaches 80% and the monitoring measurement data is stable, proceed in the following order: adding locking feet → drilling and grouting → removing the first temporary support → replacing the steel arch frame → removing the invert arch;

[0016] S700, primary drainage reinforcement: vertical grooves are dug in the side walls to bury DN75 double-wall perforated corrugated pipes, wrapped with geotextiles, with a longitudinal spacing of 5-10m, and a horizontal PVC drainage pipe is installed at the lowest point.

[0017] Preferably, in step S200, the temporary support system includes:

[0018] Temporary invert: Made of I18 I-steel welded into a ring with a longitudinal spacing of 1.2m, it is fully welded to the primary I-steel using 22mm diameter steel bars;

[0019] Diagonal bracing system: An I18 I-beam diagonal brace is installed on each of the left and right side walls in the driving direction, welded to the temporary inverted arch at a 45° angle. An I18 I-beam support is installed on each of the I-beam supports on both sides of the arch top, and is welded vertically.

[0020] Temporary inverted arch concrete filling: The temporary inverted arch is poured with 30cm thick C25 concrete, with a double-layer steel mesh with a diameter of 8@150. The formwork uses a steel mold to accurately control the contour line of the inverted arch;

[0021] Structural relationship: Before the arch is replaced, the temporary I-beam, temporary inverted arch, left and right side walls in the driving direction, and I-beam supports on both sides of the arch top are welded to form an overall closed-loop structure.

[0022] It should be added that the temporary support system also includes small grouting ducts and the arch to be replaced. The small grouting ducts and temporary I-beams before arch replacement are used to reinforce the top of the arch to be replaced to prevent landslide accidents during arch replacement.

[0023] The left and right side walls in the driving direction are made of I18 I-steel, and a 22mm diameter connecting steel plate is installed at the connection with the temporary invert arch, with a weld length of ≥8cm;

[0024] The I-beam supports on both sides of the arch are vertically welded to the arch top of the temporary inverted arch, with a distance of ≤30cm from the primary supporting steel arch frame;

[0025] Before replacing the arch, the temporary I-beam uses the same model of I18 I-beam as the initial support, and is welded at a 60° angle to the left and right side walls in the driving direction.

[0026] The construction sequence of the temporary support system is:

[0027] Erection of temporary invert;

[0028] Install the left and right side walls in the driving direction;

[0029] Install I-beam supports on both sides of the arch to form a triangular stable structure;

[0030] Pour temporary invert concrete filling and set up drainage system;

[0031] Temporary I-beams are used as secondary supports before installing the replacement arch.

[0032] Preferably, in step S300, the drainage system includes:

[0033] Drainage holes: small conduits with a diameter of 42×4mm and a length of 3.5m, an external insertion angle of 15°-20°, and a circumferential arrangement with a spacing of 5m. Drill 8mm diameter seepage holes @100mm in the conduit wall;

[0034] Drainage pipeline: DN75 double-wall corrugated pipe with an opening rate of ≥15%, pore diameter 8mm@50mm staggered arrangement, wrapped with 300g / m 2 Non-woven filter layer;

[0035] Water collection facilities: The water collection pit is 1.2m×0.8m×0.6m in size, with a built-in 300-diameter steel water collection well and two 5m 3 / h submersible pump automatically pumps water.

[0036] Preferably, the dual-liquid grouting parameters include:

[0037] Cement slurry preparation: P.O42.5 cement + water, water-cement ratio 1:1, stirring time ≥ 3 minutes;

[0038] Water glass parameters: modulus 2.4±0.2, Baume 38±1°Bé, dilution ratio 1:1 (water: stock solution);

[0039] Mixing ratio: The volume ratio of cement slurry to water glass is 1:0.6, and the JZB-250 double-liquid grouting pump is used for synchronous injection;

[0040] Grouting control: Initial pressure 0.5MPa gradually increased to 2.5MPa, final pressure maintained at 2.0-2.5MPa, grouting volume ≤1.2m 3 / m.

[0041] Preferably, the steel arch replacement includes the following steps:

[0042] S100, locking foot reinforcement: use small conduits with a diameter of 42×4mm, a length of 4.5m, an external insertion angle of 30°, 4 conduits per arch (2 on each side), and a grouting pressure of 1.5-2.0MPa;

[0043] S101, Temporary support: Install I18 I-beam diagonal braces at the locking foot guide tube position and weld them to the existing arch frame on both sides using 22mm diameter connecting steel plates (16mm thick), with a weld length of ≥8cm;

[0044] S102, Steel Arch Removal: Use a jackhammer to remove the shotcrete along the primary support outline to the steel arch, leaving an undeformed section ≥1.0m, with a vertical deviation of ≤5°;

[0045] S103, New arch installation: Calculate the I-beam cutting size (L = ΔL + 0.6m) based on the intrusion limit length (ΔL), use 22mm diameter connecting steel plates for butt connection, and perform UT testing on the welds;

[0046] S104, support and closure: Before spraying C25 concrete, install a double-layer steel mesh with a diameter of 6@200×200, set longitudinal connecting bars with a diameter of 22@80, and the spraying thickness δ≥25cm.

[0047] Preferably, monitoring and measurement adopt measurement frequency, control standards and early warning mechanism, among which:

[0048] Measurement frequency: twice a day in the initial stage of deformation, once every 48 hours after stabilization, and increased to once an hour when data is abnormal;

[0049] Control standards: arch settlement ≤ 10mm / d, horizontal convergence ≤ 5mm / d, cumulative deformation ≤ L / 40 (L is the tunnel span);

[0050] Early warning mechanism: When the deformation rate is greater than 5mm / d for three consecutive days, a second-level early warning will be activated, and excavation will be stopped immediately and support will be strengthened.

[0051] Preferably, the construction sequence of the temporary invert is as follows:

[0052] S200, I-beam installation: Lay I18 I-beams along the designed inverted arch line with a spacing of 1.2m and joints staggered ≥50cm;

[0053] S201, diagonal brace installation: Install diagonal brace I-beams on the left and right side walls in the driving direction simultaneously, and weld them at a 45° angle to the inverted arch I-beams;

[0054] S202, support installation: I-beam supports on both sides of the arch are welded vertically to form a triangular stable structure;

[0055] S203, Concrete pouring: Use C25 commercial concrete pumping, layer thickness ≤ 30cm, and vibrate and compact with an inserted vibrator;

[0056] S204. Drainage treatment: A 2% transverse slope is set on the top surface of the inverted arch, and 100-diameter PVC drainage pipes (with a spacing of 4m) are reserved and connected to the existing drainage system.

[0057] Preferably, the grouting construction comprises the following steps:

[0058] S300, Drilling process: Use full hydraulic drilling rig for drilling, drilling depth is 5.0m, hole diameter is 50mm, and deflection rate is ≤3%;

[0059] S301, segmented grouting: grouting the entire hole at one time, with a grouting section length of 4.5m and a 0.5m stop rock plate reserved;

[0060] S302, pressure control: initial pressure 0.5MPa→1.0MPa→1.5MPa three-stage pressure increase, final pressure 2.0-2.5MPa;

[0061] S303, end standard: grouting volume ≤ 0.3m 3 / m and the pressure reaches the final pressure and is maintained for 10 minutes, or the grouting volume of a single hole is ≥ 1.5 times the theoretical value.

[0062] Preferably, the initial support deformation treatment is recorded during the construction process to form a record sheet, which includes deformation measurement data, grouting parameters, and support installation time. At the same time, a curve chart is generated to record the pressure change curve and grouting volume data of each grouting hole.

[0063] Preferably, the construction quality control includes the following:

[0064] Material inspection: Cement must provide a 28-day compressive strength report, water glass must be tested for modulus and Baume, and steel arch sampling test yield strength ≥ 235MPa;

[0065] Process inspection: I-beam installation verticality deviation ≤ 2°, welding quality 100% visual inspection, sampling inspection rate ≥ 20% UT flaw detection; final inspection standard: deformation convergence value after arch replacement ≤ 2mm / 7d, leakage before secondary lining pouring ≤ 0.1L / (m 2 d) The qualified rate of lining thickness radar detection is ≥95%;

[0066] File management: generate the initial support deformation treatment record sheet and grouting pressure-flow curve technical files.

[0067] The present invention provides a method for preventing and controlling deformation of primary branches in water-rich areas of tunnels, which has the following beneficial effects compared with the existing technology:

[0068] 1. The method for preventing and controlling deformation of the initial support in the water-rich area of the tunnel is to add temporary steel arch supports. When an invert arch cannot be constructed, it can be quickly closed into a ring, effectively preventing further expansion of deformation and improving the safety factor during tunnel construction and treatment.

[0069] 2. The method for preventing and controlling deformation of the primary support in the water-rich area of the tunnel is to consolidate the soil behind the primary support through cement-water glass dual-liquid grouting, quickly sealing cracks in the tunnel surrounding rock during the rainy season, effectively reducing the impact of fissure water in the surrounding rock.

[0070] 3. The method for preventing deformation of the primary support in the water-rich area of the tunnel is to add drainage pipes and drainage pipes by slotting along the contour line between the primary support steel arch frames. This can supplement and improve the drainage system during the tunnel construction process, reduce the moisture content of the soil behind the primary support of the tunnel, alleviate the pressure on the steel arch frames, and thus significantly reduce the possibility of arch frame deformation.

[0071] 4. The method for preventing and controlling deformation of the primary support in the water-rich area of the tunnel is to add locking feet and temporary supports to the deformed parts of the arch frame, and then replace the steel arch frames one by one. While implementing it safely, it ensures that the bearing performance and the thickness of the secondary lining structure meet the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0073] Figure 2 This is a schematic diagram of adding locking feet and temporary support for the waist part of the arch in the present invention;

[0074] Figure 3 The present invention adds a schematic diagram of drainage arrangement behind the primary support;

[0075] Figure 4 An elevation view of the invention with additional locking feet;

[0076] Figure 5 This is a schematic diagram of the temporary support removal of the present invention;

[0077] Figure 6 This is a cross-sectional view of the arch replacement construction sequence of the present invention;

[0078] Figure 7 This is a cross-sectional view of the arch replacement treatment of the present invention;

[0079] Figure 8 This is the layout diagram of the small grouting conduit of the present invention.

[0080] In the figure: 1- small grouting pipe; 2- temporary I-beam before arch replacement; 3- left and right side walls in the driving direction; 4- part of the arch to be replaced; 5- I-beam supports on both sides of the arch top; 6- temporary inverted arch; 7- concrete filling of the temporary inverted arch. DETAILED DESCRIPTION

[0081] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0082] See also Figures 1-8 The present invention provides a technical solution: a method for preventing and controlling deformation of primary support in a water-rich area of a tunnel, comprising the following steps:

[0083] S100, Initial support monitoring and cross-section measurement: A set of monitoring points will be arranged every 5 meters, with one monitoring point each at the arch crown and the left and right haunches. A total station without a prism will be used to conduct 1-2 meter interval measurements of the deformation-limited sections to determine the scope of temporary support and grouting reinforcement.

[0084] S200, temporary support and inverted arch closure: Use I18 I-beams to weld the left and right primary I-beams into a closed loop, add I18 I-beam diagonal braces at the deformed arch waist, cast a 30cm thick C25 concrete temporary inverted arch, and set up a temporary drainage ditch.

[0085] S300, Drilling drainage and water diversion: small pipes with a diameter of 424mm are driven into the seepage location, spaced 5 meters apart. A water trough is set at the bottom to drain the water to the collection pit, and the drainage hole also serves as a grouting pipe;

[0086] S400, anchor grouting consolidation: Use a 424mm diameter grouting tube for radial grouting, arranged in a 1.2m×1.2m plum blossom pattern, using a mixture of cement slurry with a water-cement ratio of 1:1 and 38°Bé water glass at a volume ratio of 1:0.6. Grouting pressure is 2-2.5MPa, maintained for 10 minutes, and the grouting range extends 3m circumferentially and 0.6m longitudinally.

[0087] S500, Replacement of Steel Arch: Install a small locking duct 0.5m above the intrusion limit steel arch and inject grout. Use I18 I-beams to install a second temporary diagonal brace. Use a jackhammer to chisel away the intrusion limit, then remove the steel arch. Re-weld or install a new I18 I-beam using connecting steel plates. Install system anchors according to the design.

[0088] S600, temporary support removal: After the initial support strength reaches 80% and the monitoring measurement data is stable, proceed in the following order: adding locking feet → drilling and grouting → removing the first temporary support → replacing the steel arch frame → removing the invert arch;

[0089] It should be noted that temporary support removal can only begin after the initial support strength reaches 80% and, after analysis of monitoring and measurement data, the settlement and convergence meet regulatory requirements. The removal sequence is as follows: First, small locking guide tubes are added to the arch replacement site in accordance with design requirements, and drilling and grouting operations are performed to ensure stability during the arch replacement process. Next, a second temporary support I-beam is added to prevent collapse during the arch replacement process. Afterwards, the deformed position is chiseled out using tools such as jackhammers, and the first temporary I-beam support is removed. Subsequently, the deformed I-beam is removed, and the I-beam is cut and installed according to the arch replacement length. Steel mesh is laid, system anchors and small locking guide tubes are driven, and finally, shotcrete support is applied. Arch replacement operations are carried out in this order. Finally, the temporary invert arch support system is removed, completing the entire temporary support removal process to ensure the subsequent safety and stable progress of tunnel construction.

[0090] S700, primary drainage reinforcement: vertical grooves are dug in the side walls to bury DN75 double-wall perforated corrugated pipes, wrapped with geotextiles, with a longitudinal spacing of 5-10m, and a horizontal PVC drainage pipe is installed at the lowest point.

[0091] Furthermore, in step S200, the temporary support system includes:

[0092] Temporary invert 6: It is welded into a ring with I18 I-beams, with a longitudinal spacing of 1.2m, and is fully welded to the primary I-beams with 22mm diameter steel bars;

[0093] Diagonal bracing system: An I18 I-beam diagonal brace is installed on each of the left and right side walls 3 in the driving direction, welded to the temporary inverted arch 6 at a 45° angle. An I18 I-beam support is installed on each of the I-beam supports 5 on both sides of the arch top, and is welded vertically.

[0094] Temporary inverted arch concrete filling 7: Temporary inverted arch 6 is poured with 30cm thick C25 concrete, with a double-layer steel mesh with a diameter of 8@150. The formwork uses a steel mold to accurately control the contour line of the inverted arch;

[0095] Structural relationship: Before the arch is replaced, the temporary I-beam 2, the temporary inverted arch 6, the left and right side walls 3 in the driving direction, and the I-beam supports 5 on both sides of the arch top are welded to form an overall closed-loop structure.

[0096] It should be added that the temporary support system also includes a small grouting pipe 1 and a portion 4 to be replaced by an arch. The small grouting pipe 1 and the temporary I-beam 2 before the arch replacement are used to reinforce the top of the portion 4 to be replaced by an arch to prevent landslide accidents during the arch replacement.

[0097] The left and right side walls 3 in the driving direction are made of I18 I-steel, and a 22-diameter connecting steel plate is set at the connection with the temporary inverted arch 6, with a weld length of ≥8cm;

[0098] The I-steel supports 5 on both sides of the arch are vertically welded to the arch top of the temporary inverted arch 6, with a distance of ≤30cm from the primary supporting steel arch frame;

[0099] Before the arch is replaced, the temporary I-beam 2 uses the same model of I18 I-beam as the initial support, and is welded to the left and right side walls 3 in the driving direction at an angle of 60°.

[0100] The construction sequence of the temporary support system is:

[0101] Erect temporary invert 6;

[0102] Install the left and right side walls 3 in the driving direction;

[0103] Install I-beam supports 5 on both sides of the arch to form a triangular stable structure;

[0104] Pour temporary invert concrete fill 7 and set up drainage system;

[0105] Before installing the arch replacement, temporary I-beam 2 is used as secondary support.

[0106] Furthermore, in step S300, the drainage system includes:

[0107] Drainage holes: small conduits with a diameter of 42×4mm and a length of 3.5m, an external insertion angle of 15°-20°, and a circumferential arrangement with a spacing of 5m. Drill 8mm diameter seepage holes @100mm in the conduit wall;

[0108] Drainage pipeline: DN75 double-wall corrugated pipe with an opening rate of ≥15%, pore diameter 8mm@50mm staggered arrangement, wrapped with 300g / m 2 Non-woven filter layer;

[0109] Water collection facilities: The water collection pit is 1.2m×0.8m×0.6m in size, with a built-in 300-diameter steel water collection well and two 5m3 / h submersible pump automatically pumps water.

[0110] Furthermore, the dual-liquid grouting parameters include:

[0111] Cement slurry preparation: P.O42.5 cement + water, water-cement ratio 1:1, stirring time ≥ 3 minutes;

[0112] Water glass parameters: modulus 2.4±0.2, Baume 38±1°Bé, dilution ratio 1:1 (water: stock solution);

[0113] Mixing ratio: The volume ratio of cement slurry to water glass is 1:0.6, and the JZB-250 double-liquid grouting pump is used for synchronous injection;

[0114] Grouting control: Initial pressure 0.5MPa gradually increased to 2.5MPa, final pressure maintained at 2.0-2.5MPa, grouting volume ≤1.2m 3 / m.

[0115] Furthermore, the steel arch replacement includes the following steps:

[0116] S100, locking foot reinforcement: use small conduits with a diameter of 42×4mm, a length of 4.5m, an external insertion angle of 30°, 4 conduits per arch (2 on each side), and a grouting pressure of 1.5-2.0MPa;

[0117] S101, Temporary support: Install I18 I-beam diagonal braces at the locking foot guide tube position and weld them to the existing arch frame on both sides using 22mm diameter connecting steel plates (16mm thick), with a weld length of ≥8cm;

[0118] S102, Steel Arch Removal: Use a jackhammer to remove the shotcrete along the primary support outline to the steel arch, leaving an undeformed section ≥1.0m, with a vertical deviation of ≤5°;

[0119] S103, New arch installation: Calculate the I-beam cutting size (L = ΔL + 0.6m) based on the intrusion limit length (ΔL), use 22mm diameter connecting steel plates for butt connection, and perform UT testing on the welds;

[0120] S104, support and closure: Before spraying C25 concrete, install a double-layer steel mesh with a diameter of 6@200×200, set longitudinal connecting bars with a diameter of 22@80, and the spraying thickness δ≥25cm.

[0121] Furthermore, monitoring and measurement adopt measurement frequency, control standards and early warning mechanisms, among which:

[0122] Measurement frequency: twice a day in the initial stage of deformation, once every 48 hours after stabilization, and increased to once an hour when data is abnormal;

[0123] Control standards: arch settlement ≤ 10mm / d, horizontal convergence ≤ 5mm / d, cumulative deformation ≤ L / 40 (L is the tunnel span);

[0124] Early warning mechanism: When the deformation rate is greater than 5mm / d for three consecutive days, a second-level early warning will be activated, and excavation will be stopped immediately and support will be strengthened.

[0125] Furthermore, the construction sequence of the temporary invert is as follows:

[0126] S200, I-beam installation: Lay I18 I-beams along the designed inverted arch line with a spacing of 1.2m and joints staggered ≥50cm;

[0127] S201, diagonal brace installation: Install diagonal brace I-beams on the left and right side walls in the driving direction simultaneously, and weld them at a 45° angle to the inverted arch I-beams;

[0128] S202, support installation: I-beam supports on both sides of the arch are welded vertically to form a triangular stable structure;

[0129] S203, Concrete pouring: Use C25 commercial concrete pumping, layer thickness ≤ 30cm, and vibrate and compact with an inserted vibrator;

[0130] S204. Drainage treatment: A 2% transverse slope is set on the top surface of the inverted arch, and 100-diameter PVC drainage pipes (with a spacing of 4m) are reserved and connected to the existing drainage system.

[0131] Furthermore, the grouting construction includes the following steps:

[0132] S300, Drilling process: Use full hydraulic drilling rig for drilling, drilling depth is 5.0m, hole diameter is 50mm, and deflection rate is ≤3%;

[0133] S301, segmented grouting: grouting the entire hole at one time, with a grouting section length of 4.5m and a 0.5m stop rock plate reserved;

[0134] S302, pressure control: initial pressure 0.5MPa→1.0MPa→1.5MPa three-stage pressure increase, final pressure 2.0-2.5MPa;

[0135] S303, end standard: grouting volume ≤ 0.3m 3 / m and the pressure reaches the final pressure and is maintained for 10 minutes, or the grouting volume of a single hole is ≥ 1.5 times the theoretical value.

[0136] Furthermore, during the construction process, the deformation treatment of the initial support is recorded to form a record sheet, which includes deformation measurement data, grouting parameters, and support installation time. At the same time, a curve chart is generated to record the pressure change curve and grouting volume data of each grouting hole.

[0137] Furthermore, the construction quality control includes the following:

[0138] Material inspection: Cement must provide a 28-day compressive strength report, water glass must be tested for modulus and Baume, and steel arch sampling test yield strength ≥ 235MPa;

[0139] Process inspection: I-beam installation verticality deviation ≤ 2°, welding quality 100% visual inspection, sampling inspection rate ≥ 20% UT flaw detection; final inspection standard: deformation convergence value after arch replacement ≤ 2mm / 7d, leakage before secondary lining pouring ≤ 0.1L / (m 2 d) The qualified rate of lining thickness radar detection is ≥95%;

[0140] File management: generate the initial support deformation treatment record sheet and grouting pressure-flow curve technical files.

[0141] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0142] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0143] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preventing and controlling deformation of primary support in water-rich areas of tunnels, characterized in that: The following steps are involved: S100: Initial support monitoring and cross-section measurement: A set of monitoring points is arranged every 5 meters, with one monitoring point each at the arch crown and the left and right haunches. A total station without a prism is used to conduct 1-2 meter interval in-depth measurements of the deformation-limited sections to determine the scope of temporary support and grouting reinforcement. S200: Temporary support and inverted arch closure: Use I-beams to weld the left and right primary I-beams into a closed loop, add I-beam diagonal braces at the deformed arch waist, pour a 30cm thick C25 concrete temporary inverted arch, and set up a temporary drainage ditch; S300: Drilling drainage and water diversion: small pipes with a diameter of 424mm are driven into the seepage location, arranged at intervals of 5 meters. A water trough is set at the bottom to drain the water to the collection pit, and the drainage hole also serves as a grouting pipe; S400: Anchor grouting consolidation: Use a 424mm diameter grouting tube for radial grouting, arranged in a 1.2m×1.2m plum blossom pattern, using a mixture of cement slurry with a water-cement ratio of 1:1 and 38°Bé water glass at a volume ratio of 1:0.

6. Grouting pressure is 2-2.5MPa, maintained for 10 minutes, and the grouting range extends 3m circumferentially and 0.6m longitudinally. S500: Replace the steel arch frame: Add a small locking duct 0.5m above the intrusion limit steel arch frame and inject grout. Use I-beams to install a second temporary diagonal brace. Use a jackhammer to chisel off the intrusion limit portion and then remove the steel arch frame. Re-weld or install a new I-beam using connecting steel plates. Install system anchor bolts according to the design. S600: Temporary support removal: After the initial support strength reaches 80% and the monitoring measurement data is stable, construction will be carried out in the order of adding locking feet, drilling and grouting, removing the first temporary support, replacing the steel arch frame, and removing the invert arch; S700: Primary drainage reinforcement: Vertical grooves are dug in the side walls to bury double-wall perforated corrugated pipes, which are wrapped with geotextiles. The vertical spacing is 5 to 10 meters, and a horizontal drainage pipe is set at the lowest point.

2. A method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: In step S200, the temporary support system includes: Temporary inverted arch (6): welded into a ring by I-beams, with a longitudinal spacing of 1.2m, and connected to the primary I-beams by full welding with 22mm diameter steel bars; Diagonal bracing system: An I-beam diagonal brace is provided on each of the left and right side walls (3) in the driving direction and welded to the temporary inverted arch (6) at a 45° angle. An I-beam support (5) is provided on each of the two sides of the arch top and welded vertically. Temporary inverted arch concrete filling (7): The temporary inverted arch (6) is poured with 30cm thick C25 concrete, with double-layer steel mesh inside, and the formwork uses steel molds to accurately control the outline of the inverted arch; Structural relationship: the temporary I-steel (2) before the arch is replaced, the temporary inverted arch (6), the left and right side walls (3) in the driving direction, and the I-steel supports (5) on both sides of the arch top are welded to form an overall closed loop structure.

3. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: In step S300, the drainage system includes: Drainage holes: small conduits are 3.5m long, with an external insertion angle of 15-20° and arranged in a circumferential pattern with a spacing of 5m; Drainage pipeline: Double-wall corrugated pipe with an opening rate of ≥15%, staggered apertures, and a wrapping of 300g / m 2 Non-woven filter layer; Water collection facilities: The water collection pit measures 1.2m×0.8m×0.6m, with a built-in 300-diameter steel water collection well and a submersible pump for automatic water extraction.

4. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: The dual-liquid grouting parameters include: Cement slurry preparation: P.O42.5 cement + water, water-cement ratio 1:1, stirring time ≥ 3 minutes; Water glass parameters: modulus 2.4±0.2, Baume 38±1°Bé, dilution ratio 1:1 (water: stock solution); Mixing ratio: The volume ratio of cement slurry to water glass is 1:0.6, and the grouting pump is used for synchronous injection; Grouting control: Initial pressure 0.5MPa gradually increased to 2.5MPa, final pressure maintained at 2.0~2.5MPa, grouting volume ≤1.2m 3 / m.

5. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: The steel arch replacement comprises the following steps: S100: Locking foot reinforcement: Use small conduits with a diameter of 42×4mm, a length of 4.5m, an external insertion angle of 30°, 4 conduits per arch, and a grouting pressure of 1.5-2.0MPa; S101: Temporary support: Install I-beam diagonal braces at the locking foot guide tube position and weld them to the existing arch frame on both sides using connecting steel plates with a diameter of 22mm and a thickness of 16mm. The weld length should be ≥8cm. S102: Steel arch removal: Use a jackhammer to remove the shotcrete along the primary support contour line to the steel arch, leaving an undeformed section ≥1.0m, and the vertical deviation of the cut ≤5°; S103: New arch installation: Calculate the I-beam cutting size based on the intrusion limit length ΔL: L = ΔL + 0.6m, using 22mm diameter steel plates for butt welding, and performing flaw detection on the welds; S104: Support and closure: Install double-layer steel mesh before spraying C25 concrete, set longitudinal connecting reinforcement, and the spraying thickness δ ≥ 25 cm.

6. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: The monitoring and measurement adopts measurement frequency, control standards and early warning mechanism, among which: Measurement frequency: twice a day in the initial stage of deformation, once every 48 hours after stabilization, and increased to once an hour when data is abnormal; Control standards: vault settlement ≤ 10mm / d, horizontal convergence ≤ 5mm / d, cumulative deformation ≤ L / 40; Early warning mechanism: When the deformation rate is greater than 5mm / d for three consecutive days, a second-level early warning will be activated, and excavation will be stopped immediately and support will be strengthened.

7. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: The construction sequence of the temporary invert is as follows: S200: I-beam installation: Lay I-beams along the designed inverted arch line with a spacing of 1.2m and a staggered distance of ≥50cm between joints; S201: Diagonal brace installation: Install diagonal brace I-beams on the left and right side walls in the driving direction simultaneously and weld them at a 45° angle to the inverted arch I-beams. S202: Support installation: I-beam supports on both sides of the arch are welded vertically to form a triangular stable structure; S203: Concrete pouring: Use C25 concrete pumping to pour, layer thickness ≤ 30cm, and then vibrate and compact; S204: Drainage treatment: Set a 2% transverse slope on the top surface of the inverted arch, reserve drainage pipes, and connect to the drainage system.

8. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: The grouting construction comprises the following steps: S300: Drilling process: Use a fully hydraulic drilling rig for drilling, with a drilling depth of 5.0m, a hole diameter of 50mm, and a deviation rate of ≤3%; S301: Segmented grouting: Grouting is done in one go throughout the entire hole, with a 4.5m grouting section and a 0.5m stop rock plate. S302: Pressure control: initial pressure 0.5MPa→1.0MPa→1.5MPa three-stage pressure increase, final pressure 2.0~2.5MPa; S303: End standard: Grouting volume ≤ 0.3m 3 / m and the pressure reaches the final pressure and is maintained for 10 minutes, or the grouting volume of a single hole is ≥ 1.5 times the theoretical value.

9. The method for preventing and controlling deformation of primary support in water-rich areas of a tunnel according to claim 1, characterized in that: During the construction process, the initial support deformation treatment is recorded to form a record sheet, which includes deformation measurement data, grouting parameters, and support installation time. At the same time, a curve chart is generated to record the pressure change curve and grouting volume data of each grouting hole.

10. A method for preventing and controlling deformation of primary branches in water-rich areas of tunnels according to any one of claims 1 to 9, characterized in that: The construction quality control includes the following: Material inspection: Cement must provide a 28-day compressive strength report, water glass must be tested for modulus and Baume, and steel arch sampling test yield strength ≥ 235MPa; Process inspection: I-beam installation verticality deviation ≤ 2°, welding quality 100% visual inspection, sampling inspection rate ≥ 20% UT flaw detection; Final inspection standard: deformation convergence value after arch replacement ≤ 2mm / 7d, leakage before secondary lining pouring ≤ 0.1L / (m 2 d) The qualified rate of lining thickness radar detection is ≥95%; File management: generate the initial support deformation treatment record sheet and grouting pressure-flow curve technical files.

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