Integrated collaborative rapid treatment method for collapse of water-rich soft broken tunnel

Abstract

The invention discloses an integrated collaborative rapid treatment method for collapse of a water-rich soft broken tunnel, which follows the core principle of surrounding rock modification, active support, step-by-step control and dynamic sealing, and comprises four key links of step-by-step consolidation grouting, advance support, steel arch replacement and timely follow-up concrete lining construction. And an integrated treatment system with closely linked working procedures and cooperative space effects is constructed, and comprehensive management and control and rapid construction recovery of collapse disasters are achieved. By optimizing the construction process and key technical parameters, the problems of process splitting, poor consolidation effect, passive support, long treatment period and the like of a traditional method under the water-rich soft broken surrounding rock condition are effectively solved, and the controllability and operation safety of collapse section construction are remarkably improved. Meanwhile, a reproducible and generalizable technical system and engineering reference are provided for collapse prevention and emergency treatment of underground engineering under similar geological conditions, and the method has important theoretical value and wide engineering application prospects.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering disaster prevention and repair technology. Specifically, it is an integrated and rapid treatment method for tunnel collapses in water-rich, soft, and fractured strata, applicable to emergency rescue and restoration work in extremely adverse geological sections of underground engineering projects such as water conservancy and hydropower. Background Technology

[0002] The construction of underground water conservancy and hydropower tunnels often requires traversing complex and variable geological environments. Among these, water-rich, weak, and fractured strata (such as fault fracture zones, weathering troughs, and strongly altered zones) are among the most challenging adverse geological conditions during construction. These strata generally exhibit characteristics such as loose structure, poor cementation, short self-stabilization time, and easy softening and disintegration upon contact with water. After tunnel excavation and unloading, the presence of groundwater not only reduces the rock mass strength and friction coefficient but also generates significant seepage pressure, creating a vicious cycle of "excavation disturbance - groundwater erosion - strength deterioration." This can easily induce face instability, large deformation of surrounding rock, mudslides, sand inrushes, and even sudden large-scale collapses behind the face. Such disasters not only seriously threaten the safety of personnel and equipment but also often lead to severe delays in the construction period and result in huge economic losses.

[0003] To address the aforementioned disasters, traditional treatment methods typically follow a passive approach of "drainage, blocking, consolidation, and support," employing phased and localized technical measures. Common practices include: first, draining water from the surface or inside the cave to reduce water pressure; then, using pre-supporting pipes or pipe roofs; grouting to consolidate the collapsed loose material; and finally, erecting steel arches and spraying concrete for strong support. However, under the unique and challenging engineering conditions of water-rich, soft, and fractured surrounding rock, these traditional methods reveal systemic deficiencies and limitations in effectiveness:

[0004] (1) Fragmented processes and poor coordination: Drainage, grouting, support and other processes are often carried out in separate steps with poor connection and fail to form a synergistic effect in time and space. During the process transition, the stress of the surrounding rock is constantly adjusted, which can easily lead to secondary instability and fall into a passive cycle of "collapse-treatment-collapse".

[0005] (2) Limited consolidation effect, making it difficult to form an effective load-bearing arch: In a dynamic water environment, conventional grouting materials are easily diluted and washed away by water flow. The grout diffusion range and the strength of the consolidated body are difficult to control, resulting in an unsatisfactory modification effect on loose and broken bodies. It is impossible to form an "artificial load-bearing arch" with sufficient strength and integrity, and the foundation of the temporary support system is weak.

[0006] (3) The support structure is passively stressed, resulting in high safety risks: Traditional steel arch support is mostly erected after the surrounding rock deformation occurs, and it is a passive load-bearing structure. Under continuous uneven deformation and eccentric load, the support structure is prone to twisting and breaking, and needs to be repeatedly dismantled and replaced. This not only results in low construction efficiency, but also greatly increases the time that workers are exposed in the danger zone.

[0007] (4) Long treatment cycle and high cost: The combination of the above problems makes the entire emergency treatment process lengthy and repetitive. A lot of time is spent waiting for the grout to solidify, the support structure to stabilize and the secondary problems to be dealt with. It is impossible to achieve the goal of quickly controlling the danger and resuming construction, resulting in a sharp increase in manpower, material and time costs.

[0008] Therefore, developing a rapid treatment method capable of systematically modifying the surrounding rock, actively controlling loads, and integrating various processes into a coordinated manner has become an urgent need to overcome the technical challenges of water-rich, weak, and fractured tunnel collapses. The core objective of this method is to transform loose, fractured, and water-rich hazardous materials into a stable and permanent load-bearing system composed of modified surrounding rock and artificial structures in the shortest possible time, thereby safely and efficiently traversing such extremely adverse geological sections and breaking through the bottlenecks of traditional technologies. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention provides an integrated and rapid treatment method for the collapse of water-rich, soft, and fractured tunnels, which aims to solve the problems of fragmented procedures, poor consolidation effect, passive support, and long treatment cycle of traditional methods, and realize rapid control of collapse disasters and efficient construction recovery.

[0010] The objective of this invention is achieved as follows: an integrated, collaborative, and rapid treatment method for water-rich, weak, and fractured tunnel collapses, comprising the following steps:

[0011] S1. Steps for sealing off the collapsed area: Spray a certain thickness of concrete onto the top of the collapsed area to seal it off;

[0012] S2, Consolidation grouting steps for the collapsed top area: Perform consolidation grouting treatment on the collapsed top area;

[0013] S3. Secondary sealing steps for the collapsed area at the top: Fill the cavity formed by the collapse with concrete;

[0014] S4. Steps for advanced pipe roof support and advanced consolidation grouting;

[0015] S5. Cleaning up the slag heap and grouting the side walls;

[0016] S6. Steps for replacing the steel arch frame;

[0017] S7. The step of immediately carrying out tunnel lining concrete construction after the steel arch frame is replaced.

[0018] S8. Steps for monitoring and feedback of surrounding rock in tunnel collapse repair section.

[0019] Furthermore, in step S1, after the tunnel face collapses and stabilizes, a construction platform with a certain height is formed by backfilling with rock slag, and concrete is sprayed onto the collapsed area at the top of the construction platform to seal it.

[0020] Furthermore, in step S2, the top area of ​​the tunnel face is first consolidated and grouted using a grouting trolley, and then the corresponding surface collapse area is consolidated and grouted.

[0021] Furthermore, in step S3, after the consolidation grout strength reaches the design value, the cavity area formed by the collapse along the outer contour of the tunnel is sealed with the help of a support trolley and support materials, so that the collapsed cavity area forms the tunnel design contour, and concrete is used to fill the cavity formed by the collapse in a timely manner.

[0022] Furthermore, in step S4, after the collapse treatment of the tunnel top is completed, the slag heap is partially cleared, and concrete is sprayed in time after the tunnel face is exposed. Then, advanced pipe roof and advanced consolidation grouting treatment are carried out according to the design requirements.

[0023] Furthermore, in step S5, muck trucks are used to clear the collapsed material, slag heaps, and nearby mud and water from the collapsed area, and temporary steel support frames are quickly erected to ensure construction safety in the tunnel face area. Next, a grouting trolley is used to perform consolidation grouting on the collapsed and deformed areas of the tunnel sidewalls. The grouting material used in step S5 is the same as that used in step S2, both being fast-setting, high-strength consolidation grouting materials.

[0024] Furthermore, in step S6, after the steel arch frame is dismantled, under-excavation is carried out using a hydraulic hammer or a pneumatic pick, the original anchor bolts are retained, and the original steel structure is cut off until the tunnel outline meets the construction and design requirements; after the surrounding rock surface is repaired, initial shotcreting is carried out in a timely manner, and steel mesh is hung through the original anchor bolts; after the mesh is installed, the corresponding processed steel arch frame units are transported to the work surface, adjusted and positioned for installation; concrete pads are added in the gap between the steel arch frame and the initial shotcrete to wed the steel arch frame tightly.

[0025] Furthermore, in step S7, the following procedures are followed:

[0026] S71. Before lining with concrete, the bottom slab needs to be cleaned down to the bedrock surface. After acceptance, the steel reinforcement is tied and the embedded parts are installed according to the design drawings.

[0027] S72. After the reinforcement binding is completed and accepted, the bottom slab concrete is poured and cured, and a water-stop structure is set as required.

[0028] S73. Then, use a steel bar tying trolley to tie the steel bars for the side walls and the top arch.

[0029] S74. Once the steel reinforcement is installed and passes inspection, set up the lining steel formwork trolley, install the steel formwork needed for the pouring process, connect the concrete pump, and carry out the pouring operation of the tunnel lining concrete.

[0030] S75. After the strength reaches the design requirements, remove the formwork and cure the poured concrete structure.

[0031] Furthermore, in step S4, when constructing the advanced large pipe shed, the measurement and layout are carried out first, and the location of the pipe shed is marked on the working face.

[0032] Furthermore, in step S8, monitoring devices are installed on the surface of the surrounding rock (including sidewalls and top arch) to monitor the deformation of the surrounding rock in real time.

[0033] The beneficial effects of this invention are as follows:

[0034] This method follows the core principles of "surrounding rock modification, active support, step-by-step control, and dynamic closure." Through four key steps—step-by-step consolidation grouting, advanced support, replacement of steel arch frames, and timely follow-up concrete lining construction—it achieves comprehensive control and rapid recovery from landslide disasters.

[0035] "Consolidation grouting" mainly uses fast-setting, high-strength grout (such as cement-water glass dual-liquid grout) to perform staged penetration-compaction grouting on the collapsed loose material and surface subsidence area, transforming the loose medium into an "artificial consolidated body" with a certain strength and integrity, thereby rebuilding the self-supporting system of the surrounding rock. In addition, "consolidation grouting" also implements radial consolidation grouting in the sidewall collapse area to form a complete temporary bearing ring in conjunction with the solidified collapsed roof slab.

[0036] During the "advanced support" stage, a high-strength, continuous advanced composite support arch is constructed in the unexcavated loose body in front of the tunnel face by constructing advanced pipe roofs and supplementing them with grouting reinforcement. This enables the active bearing and effective transfer of the load in front, providing reliable pre-protection for the core excavation process and preventing secondary collapses during construction.

[0037] During the "steel arch frame replacement" phase, the steel arch frames near the working face that were deformed and damaged due to the collapse were dismantled and replaced to restore the integrity and load-bearing capacity of the support structure in a timely manner.

[0038] The "concrete lining" in "timely follow-up on concrete lining" refers to a rigid lining structure (such as reinforced concrete). It makes full use of the "spatiotemporal effect" window after the surrounding rock is reinforced to complete the final transformation of the load system from temporary support to permanent structure, forming a high-strength, permanent tunnel bearing shell to ensure the long-term stability and safe operation of the tunnel.

[0039] The above four key technical steps are advanced sequentially and closely linked: "consolidation grouting" is used to modify the surrounding rock, providing a stable foundation for "advanced support"; "advanced support" ensures the safety and stability of the excavation process; after "replacing the steel arch frame", "concrete lining construction is carried out in a timely manner" to achieve rapid closure and overall load-bearing of the permanent load-bearing structure in the shortest possible time.

[0040] This invention, through systematic intervention, gradually transforms water-rich, weak, and fractured geological bodies from passive loads into media with a certain self-supporting capacity, and ultimately allows artificial structural systems to take over the load, forming a dynamic, collaborative, efficient, and reliable comprehensive management system for tunnel collapses. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the core steps of the present invention;

[0042] Figure 2 This is a schematic diagram of the core step S1 of the present invention;

[0043] Figure 3 This is a schematic diagram of the core step S2 of the present invention;

[0044] Figure 4 This is a schematic diagram of the core step S3 of the present invention;

[0045] Figure 5 This is a schematic diagram of the core step S4 of the present invention;

[0046] Figure 6 This is a schematic diagram of the core step S5 of the present invention;

[0047] Figure 7 This is a schematic diagram of the core step S6 of the present invention;

[0048] Figure 8 This is a side view of the core step S7 of the present invention.

[0049] Figure 9 This is a cross-sectional schematic diagram of the core step S7 of the present invention.

[0050] Figure 10 This is a schematic diagram of the core step S8 of the present invention. Detailed Implementation

[0051] The following will refer to the appendices in the embodiments of the present invention. Figure 1-10The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] The preferred application scenarios / operating conditions are described in detail below:

[0053] Currently, the access tunnel for a pumped storage power station under construction is approximately 1500m long. The surrounding rock of the tunnel mainly includes Class II, III, IV, and V rock types. During construction, multiple adverse geological structures were encountered, resulting in varying degrees of collapse in the affected areas. On-site investigation revealed that the exposed surrounding rock in the adverse areas was mostly in a state of complete to strong weathering, quite fractured, sandy, and poorly cohesive. Simultaneously, the corresponding overburden layers were shallow (not exceeding 170m), making them susceptible to the combined effects of surface seepage and groundwater. This caused the extremely fractured surrounding rock in the adverse geological structure zone to continuously experience water seepage and instability during construction, presenting technical challenges such as constant risks of collapse, tight schedules, and high safety requirements.

[0054] like Figure 1 As shown, an integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapses is provided, including the following core steps:

[0055] S1. Steps for sealing off the collapsed area;

[0056] S2, Steps for consolidation grouting in the collapsed top area;

[0057] S3, Secondary sealing of the collapsed area at the top;

[0058] S4. Steps for advanced pipe roof support and advanced consolidation grouting;

[0059] S5. Cleaning up the slag heap and grouting the side walls;

[0060] S6. Steps for replacing the steel arch frame;

[0061] S7. The step of immediately carrying out tunnel lining concrete construction after the steel arch frame is replaced.

[0062] S8. Steps for monitoring and feedback of surrounding rock in tunnel collapse repair section.

[0063] The steps described above are explained in detail below.

[0064] S1. Steps for sealing off the collapsed area:

[0065] like Figure 2As shown, a collapse occurred in the weak and fractured zone of the tunnel. The damaged part 3a of the steel arch frame 3 was caused by the collapse accident. After the collapse process stabilized, the silt-like collapsed body was removed, and the slag pile at the tunnel face was left untreated. High-quality stone chips were used for backfilling to form a construction platform 1 with a certain height and strength. There is a certain distance between the construction platform 1 and the top of the tunnel. Based on the construction platform 1, concrete was sprayed onto the collapsed area at the top to seal it. C25 concrete was used, and the operation of spraying concrete was carried out using a pressure spray gun 2. The thickness of the concrete was 30cm. After the strength of the sprayed concrete in the collapsed area reached 70% of the design strength, the next process was carried out.

[0066] In this step, such as Figure 2 As shown, a material storage 5, a power station 4, and a steel arch frame 3 are arranged. The steel arch frame 3 is used to support the slightly weathered rock mass (several anchor rods 6 are fixed in the rock mass). The damaged part 3a of the steel arch frame 3 is located on one side of the construction platform 1. The material storage 5 is used to provide the grouting materials required for construction, and the power station 4 is used to provide the power source required for construction.

[0067] S2. Steps for consolidation grouting in the collapsed top area:

[0068] like Figure 3 As shown, after the concrete strength on the surface of the top collapsed area reaches the design requirements, consolidation grouting begins in the collapsed area. First, consolidation grouting is performed on the top area of ​​the tunnel face. The grouting pump 9, in conjunction with the grouting trolley 10, provides the grouting pressure during the consolidation grouting process, and grouting is carried out in the top collapsed area to form the lower consolidated grout body 11. Then, consolidation grouting is performed on the corresponding vertically corresponding surface collapsed area (sinking area 7), that is, grouting is carried out in the sinking area 7 to form the upper consolidated grout body 8, giving the collapsed area a certain structural strength to prevent subsequent collapses during the collapse treatment process. The consolidation grouting material should have significant characteristics such as rapid setting and high strength, and important parameters such as the corresponding grouting holes and grout should be reasonably set.

[0069] In this embodiment, the consolidation grouting adopts the cement-water glass two-liquid grouting method, with two rows of grouting holes arranged alternately. The parameters for a single row of grouting holes are: hole diameter 56mm, hole depth 8m, spacing between rows 1.0m × 1.0m, outer grouting hole inclination angle 5°, and inner grouting hole inclination angle 15°. The parameters for the cement-water glass two-liquid grout are: cement 42.5R ordinary Portland cement; retarder disodium hydrogen phosphate; water glass modulus 2.4–3.4, concentration 22–40Be′; water-cement ratio 0.8:1.0–1.0:1.0; cement grout to water glass volume ratio 1:1–1:0.8; retarder dosage <10%; gel time 30–60s. After treating the collapsed area inside the tunnel, to prevent subsequent collapses, it was decided to perform consolidation grouting on the collapsed area from outside the tunnel. The grout used is a cement-water glass dual-liquid grout, and the grouting depth is set at 9m. Other parameters are consistent with those for tunnel pre-consolidation grouting.

[0070] S3. Secondary sealing steps for the collapsed area at the top:

[0071] like Figure 4 As shown, after the consolidation grout strength reaches the design value, the cavity area formed by the collapse along the outer contour of the tunnel is sealed / filled with support material 13. Several reinforcing anchor bolts 12 are fixedly installed in the support material 13 to strengthen the sealing structure, so that the collapsed cavity area forms the tunnel design contour. Concrete is then promptly used to fill the collapsed cavity. Support materials include, but are not limited to, anchor bolts, reinforcing bars, and reinforcing mesh. The support trolley 14 is mainly used for filling the support material 13 and installing additional reinforcing anchor bolts 12.

[0072] During backfilling, self-compacting concrete is poured using a ground pump. Concrete pouring can be stopped once the vent holes discharge concrete outwards.

[0073] The concrete pouring pipe uses φ100-φ200 steel pipe, and the exhaust pipe uses φ100 steel pipe. Both pre-embedded pipes should be securely fixed with anchor bolts. The collapsed area is sealed with steel bars and steel mesh along the outer contour of the tunnel, forming the designed tunnel outline. Then, shotcrete is applied to seal the area. The shotcrete thickness should be no less than 20cm. A wet shotcrete machine is used; to reduce rebound, the nozzle should be perpendicular to the sprayed surface, preferably 0.6m-1.2m away.

[0074] S4. Steps for advanced pipe roof support and advanced consolidation grouting:

[0075] like Figure 5 As shown, after the collapse treatment of the tunnel top is completed, the slag heap is partially cleared. After the tunnel face is exposed, concrete is sprayed in time. Then, according to the design requirements, advanced pipe roof and advanced consolidation grouting are carried out to form an advanced pipe roof structure 15 inside the collapse area.

[0076] The grouting method for step S4 is full-hole injection, using ordinary cement grout (or other special mixed materials, taking into account groundwater development). Grouting is carried out according to the principle of bottom-to-top and thinner-to-thicker grout. Furthermore, during the construction of the advanced large pipe roof, surveying and setting out are conducted first, marking the location of the pipe roof on the working face.

[0077] The pipe roof uses hot-rolled seamless steel pipes with an outer diameter of 108mm and a wall thickness of 6mm. Each section of steel pipe has pre-processed external threads at both ends for connecting joint pipes. Each section of steel pipe is 1.5m long. The number of joints within the same cross-section of the steel pipe and the steel perforated pipe should not exceed 50% of the total number of pipes. The ring spacing is 30cm; the external insertion angle is 1-2°, which can be adjusted according to site conditions. The pipe roof length is 8-15m. Grouting holes are drilled on the steel perforated pipes, with a diameter of 10-16mm and a hole spacing of 20cm, arranged in a quincunx pattern. A grout-stopping section of at least 1m is left at the end without drilling. The longitudinal spacing should ensure an overlap length of at least 3m for the pipe roof. The pipe roof is constructed using the pipe-following (each section of steel pipe is 1.5 meters long) drilling method. During drilling, the drill rod axis should be strictly controlled. The drilling platform should be solid and reliable, and the drilling rig should be firmly fixed. During drilling, the drilling deviation should be monitored, and corrections should be made promptly if it exceeds the design requirements. After passing inspection, the steel pipes are continuously spliced ​​together to a total length of 10 sections, 15m deep, and inserted into the hole using a drilling rig with a rotating jack. The steel pipes are joined using threaded connections.

[0078] After the borehole is cleaned and inspected and found to be qualified, grouting is carried out. The grout is made of R42.5 ordinary Portland cement with a water-cement ratio of 1:0.75 to 1:1. When groundwater is abundant, the grout is changed to cement-water glass with a water glass concentration of 35 to 40 Be'. The grouting pressure is 0.5 to 1.0 MPa, and the termination pressure is 1.0 to 1.5 MPa. The grouting parameters should be adjusted according to the actual situation during construction.

[0079] Cement grout is injected into the large pipe shed using a full-hole injection method, employing a high-power grouting pump. Before grouting, a field grouting test is conducted to determine the grouting parameters and admixture dosage before actual construction. Grouting follows the principle of bottom-up and thin-to-thick grout. The grout volume is controlled by pressure; once the completion standard is reached, the stop valve is closed to stop grouting. If deformation or damage to the support is detected during grouting, grouting must be stopped immediately, and measures taken. If cross-grouting occurs, the cross-grouting holes must be plugged promptly, or two holes must be grouted simultaneously. A sudden increase in grouting pump pressure may cause pipe blockage; in this case, the pump must be stopped immediately for inspection, and the grouting pipeline must be cleaned promptly.

[0080] After the pre-grouting is completed, pre-consolidation grouting should be carried out promptly. The pre-consolidation grouting length is 9m per cycle, with a borehole diameter of 56mm, tentatively for 2 cycles. A ZLJ-1200 hydraulic drill should be used. The drilling report should accurately record the drilling depth, borehole collapse, cavities, color and pressure of the borehole flushing water, etc. After drilling, borehole flushing should be performed using a guide pipe to introduce a large flow of water from the bottom of the borehole to the outside. The thickness of residual sediment in the borehole after flushing should not exceed 20cm. All grouting holes should be flushed before grouting, using water pressure at 80% of the grouting pressure; if the pressure exceeds 1MPa, use 1MPa. The flushing time should continue until the return water is clear or not exceed 20 minutes. Fracture flushing should not be performed if there are adjacent grouting holes or if the adjacent grouting holes have been completed less than 24 hours ago. For formations whose properties are easily deteriorated after contact with water, fracture flushing may be omitted.

[0081] S5. Cleaning up the slag heap and grouting the side walls:

[0082] It should be noted that, Figure 6 Divided into two parts, a and b. Figure 6 Part a in the diagram shows the longitudinal cross-sectional view of step S5. Figure 6 Part b shows the cross-sectional view of step S5.

[0083] like Figure 6 As shown, firstly, the slag heap, debris, and nearby mud and water in the collapsed area were cleared using a slag removal truck 16, and a temporary steel support frame 17 was quickly erected to ensure construction safety in the tunnel face area. Next, a grouting trolley was used to perform consolidation grouting on the collapsed area 18 of the tunnel sidewall, and sidewall reinforcement anchors 19 were used for reinforcement. The grouting material used in step S5 was the same as that used in step S2, both being fast-setting, high-strength consolidation grouting material, preferably a cement-water glass dual-liquid grout. The grouting hole diameter was 56mm, and the hole depth was 8m. Other grouting parameters were the same as those at the tunnel face. Grouting holes 20 were arranged in a quincunx pattern at 3m intervals from JT0+243 to 0+253 on the right side wall. The grouting pressure, grout mix ratio, and other parameters are not detailed here.

[0084] S6. Steps for replacing the steel arch frame:

[0085] like Figure 7 As shown, after the grouting strength of the sidewalls reaches the design specification value, the damaged part 3a of the original deformed steel arch frame 3 is replaced, and the newly installed part 3b replaces the original damaged part 3a. The initial support replacement is carried out in the order of replacement from small mileage to large mileage. First, the top arch and the top arch connecting bars are cut, and then the side wall arch frames and connecting bars are cut. Then the cross-section is broken down to the design cross-section size, and the initial support is carried out according to the design requirements.

[0086] The specific procedure involves marking the measurement results on the tunnel sidewall with red spray paint, then chiseling away according to the marked numbers. Once the steel arch frame is exposed, it is removed using an oxy-acetylene torch. The removal of shotcrete is carried out layer by layer from the clear face to the surrounding rock face, with each removal step not exceeding 1 meter. First, the top arch and its connecting reinforcement are cut, followed by the side wall arch frames and their connecting reinforcements. The cross-section is then broken down to the design dimensions, and initial support is provided according to design requirements. Before removing the shotcrete, the section to be removed must be cut and separated from the section not to be removed at the boundary to prevent damage to the remaining concrete. Large-scale removal of the initial support is prohibited, and the length of each removal step should not exceed 1 meter. If the consolidation effect is good, the length may be appropriately increased with the permission of the supervising engineer to prevent collapse and roof fall. The replacement location, the number of steel arch frames processed, and the area of ​​concrete removed can be confirmed by on-site technical personnel.

[0087] After the steel arch frame is dismantled, under-excavation is carried out using a hydraulic hammer or manual pneumatic pick. The original anchor bolts are retained, and the original steel structure is removed until the tunnel outline meets the construction and design requirements. After the surrounding rock surface is repaired, initial shotcreting is carried out in a timely manner, and steel mesh is hung through the original anchor bolts. After the mesh is installed, the corresponding processed steel arch frame units are transported to the work surface, adjusted, and positioned for installation. Concrete pads are added in the gap between the steel arch frame and the initial shotcrete to wed the steel arch frame tightly.

[0088] According to design requirements, I22a I-beams are used, with a longitudinal spacing of 0.5m. C22 steel bars are used for longitudinal connections and welded according to design requirements. The anchor bolts are made of C25 steel bars, with an angle of not less than 45° to the steel arch frame, a length of 3m, and two bolts at each connection plate node. The construction of the anchor bolts and the welding of the U-shaped reinforcement must be completed under the supervision of the on-site technician. Grouting of the anchor bolts uses cement mortar with a strength of not less than M20, with a grouting pressure of 0.5–1 MPa.

[0089] When replacing the first steel frame, the longitudinal connections are welded to the existing longitudinal connecting bars, and C22 steel bars are used for back welding. During shotcreting, the steel arch frames near the working face are not end-sealed to ensure the connection between the connecting bars and the steel frame in the next cycle. If the existing steel arch frame connecting plates are intact, they are directly connected using connecting plates and bolts; if the existing steel arch frame connecting plates are damaged, they are replaced on-site, and 40*40mm angle steel is used for back welding to ensure the connection between the steel arch frames.

[0090] After each steel arch frame is replaced and inspected, C25W6 concrete should be wet-sprayed to a thickness of not less than 30cm, ensuring a dense and void-free finish. The next construction cycle can only begin 3 hours after the concrete spraying is completed. When spraying concrete, the nozzle should be approximately perpendicular to the surface being sprayed, 0.6–1.2m away. Spraying should be carried out in sections, sequences, and layers, from bottom to top. Large depressions should be filled first. During spraying, the nozzle should be rotated repeatedly and slowly in a spiral motion, with a spiral diameter of approximately 20–30cm, following the principle of spraying walls first, then arches. When spraying in layers to gradually increase thickness, the next layer should be applied after the previous layer has fully set to ensure smoothness. If spraying is to be done again 1 hour after final setting, the surface of the previous sprayed layer should be cleaned with water before proceeding with the next spraying. There should be a 200mm overlap between the sprayed concrete layers in two cycles, and the difference in undulation at the overlap should be controlled within the allowable range. The sprayed concrete surface should be flat, with an average undulation difference controlled within 100mm.

[0091] S7. Steps for immediately carrying out tunnel lining concrete construction after the steel arch frame replacement:

[0092] like Figure 8-9 As shown, after the steel arch frame was replaced, in order to ensure that the collapsed section would not collapse again, the tunnel lining concrete construction was carried out immediately.

[0093] In step S7, the following procedures shall be followed:

[0094] S71. Before lining with concrete, the bottom slab needs to be cleaned down to the bedrock surface. After acceptance, the steel reinforcement is tied and the embedded parts are installed according to the design drawings.

[0095] S72. After the reinforcement binding is completed and accepted, the bottom slab concrete is poured and cured, and a water-stop structure is set as required.

[0096] S73. Then, use a steel bar tying trolley to tie the steel bars for the side walls and the top arch.

[0097] S74. Once the reinforcement is installed and accepted, set up the lining steel formwork trolley 21 and install the steel formwork (using the steel formwork to form the mold for concrete) to be used in the pouring process. Connect the concrete pump and use the concrete pump to inject concrete into the steel formwork cavity of the lining steel formwork trolley to carry out the pouring operation of tunnel lining concrete (the concrete can be vibrated), forming a reinforced concrete lining 22 on the inner wall of the tunnel.

[0098] S75. After the concrete reaches the design strength, remove the steel formwork from the trolley and cure the poured concrete structure. Curing agents can be used to cure the poured concrete structure, or high-temperature steam curing can be used. The curing method is not limited to one method.

[0099] S8. Steps for monitoring and feedback of surrounding rock in tunnel collapse repair section:

[0100] like Figure 10 As shown, after the secondary reinforcement of the lining concrete is completed, monitoring devices are installed on the surface of the surrounding rock to monitor the deformation of the surrounding rock in real time. Figure 10 From a visual perspective, monitoring points 23 were set up at the top, left, and right to conduct monitoring, and the stability of the surrounding rock was evaluated based on the monitoring results. The economy and effectiveness of the rapid collapse treatment technology were analyzed.

[0101] The combined rapid collapse treatment method of "grouting consolidation + advanced support + arch frame replacement and concrete lining construction" adopted by the above method can effectively cope with complex hydrogeological conditions such as weak and broken surrounding rock, serious groundwater leakage and continuous surface rainfall infiltration. It provides reliable technical support for the safe and continuous excavation of the access tunnel on the critical route, thereby ensuring the smooth progress of the overall project.

[0102] The technical innovation of this method lies in:

[0103] A) Sequential consolidation grouting using rapid-setting, high-strength consolidation grouting materials:

[0104] Compared to conventional cement grout or cement mortar, this invention uses a fast-setting, high-strength consolidation grouting material with reasonable proportioning parameters, preferably a cement-water glass dual-liquid grout, which possesses outstanding properties of rapid setting and high strength. The consolidation grouting operation is carried out in a scientifically ordered, step-by-step manner: first, grouting is performed around the collapsed cavity at the tunnel face and the corresponding surface subsidence area to inhibit further development of the collapsed cavity; then, advanced pipe roof and advanced consolidation grouting are carried out to prevent the risk of tunnel face collapse; finally, consolidation grouting is carried out on the sidewalls and the outer perimeter of the tunnel roof to prevent further collapse during subsequent construction, significantly improving the safety and reliability of the support system.

[0105] B) After consolidation, replace the deformed steel arch frame and simultaneously advance the concrete lining construction:

[0106] To address the complex geological challenges posed by landslides in water-rich, weak, and fractured zones, including widespread water seepage, rock weathering and fracturing, and surface rainfall infiltration in shallowly buried areas, this invention proposes a systematic dismantling of deformed steel arches in the collapsed section after consolidation. Following surface treatment, new steel arches meeting design requirements are then reinstalled and reliably supported. Simultaneously, an innovative method of using a temporary bridge starting from the tunnel entrance is employed for the foundation slab concrete pouring, ensuring uninterrupted traffic within the tunnel and allowing for simultaneous and timely concrete lining construction of the sidewalls and roof arch. This method not only guarantees construction safety and smooth project progress but also effectively shortens the construction period and achieves significant economic benefits.

[0107] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In this invention, it should also be noted that the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integrally formed connection, a mechanical connection, or an indirect connection through intermediate connecting parts. The specific meaning of the terms in this utility model can be understood according to the specific circumstances.

[0108] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0109] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An integrated, collaborative, and rapid treatment method for water-rich, weak, and fractured tunnel collapses, characterized in that: The steps include the following: S1. Steps for sealing off the collapsed area: Spray a certain thickness of concrete onto the top of the collapsed area to seal it off; S2, Consolidation grouting steps for the collapsed top area: Perform consolidation grouting treatment on the collapsed top area; S3. Secondary sealing steps for the collapsed area at the top: Fill the cavity formed by the collapse with concrete; S4. Steps for advanced pipe roof support and advanced consolidation grouting; S5. Cleaning up the slag heap and grouting the side walls; S6. Steps for replacing the steel arch frame; S7. The step of immediately carrying out tunnel lining concrete construction after the steel arch frame is replaced. S8. Steps for monitoring and feedback of surrounding rock in tunnel collapse repair section.

2. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 1, characterized in that, In step S1, after the tunnel face collapses and stabilizes, a construction platform with a certain height is formed by backfilling with rock slag, and concrete is sprayed onto the collapsed area at the top of the construction platform to seal it.

3. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 1, characterized in that, In step S2, first, consolidation grouting is performed on the top area of ​​the tunnel face, and then consolidation grouting is performed on the corresponding vertical surface collapse area.

4. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 3, characterized in that, In step S3, after the consolidation grout strength reaches the design value, the cavity area formed by the collapse along the outer contour of the tunnel is sealed with support material so that the collapsed cavity area forms the tunnel design contour, and the cavity formed by the collapse is filled with concrete in a timely manner.

5. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 1, characterized in that, In step S4, after the collapse at the top of the tunnel is treated, the slag heap is partially cleared. Once the tunnel face is exposed, concrete is sprayed in time, and then advanced pipe roof and advanced consolidation grouting are carried out according to the design requirements.

6. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 3, characterized in that, In step S5, the collapsed body, slag heap, and nearby mud and water in the collapsed area are cleaned up together. The support trolley is used to perform consolidation grouting on the collapsed and deformed area of ​​the tunnel sidewall. The grouting material used in step S5 is the same as that used in step S2, which is a fast-setting high-strength consolidation grouting material.

7. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 1, characterized in that, In step S6, after the steel arch frame is dismantled, under-excavation is carried out using a hydraulic hammer or a pneumatic pick, the original anchor bolts are retained, and the original steel structure is cut off until the tunnel outline meets the construction and design requirements; after the surrounding rock surface is repaired, initial shotcreting is carried out in a timely manner, and steel mesh is hung through the original anchor bolts; after the mesh is installed, the corresponding processed steel arch frame units are transported to the work surface, adjusted and positioned for installation; concrete pads are added in the gap between the steel arch frame and the initial shotcrete to wed the steel arch frame tightly.

8. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 1, characterized in that, In step S7, the following procedures shall be followed: S71. Before lining with concrete, the bottom slab needs to be cleaned down to the bedrock surface. After acceptance, the steel reinforcement is tied and the embedded parts are installed according to the design drawings. S72. After the reinforcement binding is completed and accepted, the bottom slab concrete is poured and cured, and a water-stop structure is set as required. S73. Then, use a steel bar tying trolley to tie the steel bars for the side walls and the top arch. S74. Once the steel reinforcement is installed and passes inspection, set up the lining steel formwork trolley, install the steel formwork needed for the pouring process, connect the concrete pump, and carry out the pouring operation of the tunnel lining concrete. S75. After the strength reaches the design requirements, remove the formwork and cure the poured concrete structure.

9. The integrated and rapid treatment method for water-rich, weak, and fractured tunnel collapse according to claim 5, characterized in that, In step S4, when constructing the advanced large pipe shed, the first step is to measure and mark the location of the pipe shed on the working face.

10. A method for the integrated and rapid treatment of water-rich, weak, and fractured tunnel collapse according to any one of claims 1-9, characterized in that, In step S8, a monitoring device is deployed on the surface of the surrounding rock to monitor the deformation of the surrounding rock in real time.

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