Bolt-grouting water plugging support method for water-rich fault roadway

Abstract

The invention relates to the technical field of coal mine tunnel support and water disaster prevention and control, and discloses a bolting-grouting water plugging support method for a water-rich fault tunnel, which comprises the following steps: forming a shallow foundation support along with tunneling construction of a common anchor rod; a deep reinforcing anchor rod is constructed in the first lagging aging to form a deep reinforcing support; grouting anchor rods are arranged; and after second lagging aging after tunneling is finished, modified cement grout is prepared for grouting plugging, and the modified cement grout is prepared from Portland cement, water and a composite additive containing aluminate clinker, polyacrylamide and the like. According to the method, through a space-time cooperative control strategy of shallow surface protection deep suspension lagging grouting, repairing is carried out in the optimal window period of fracture development by using the rheological characteristics of surrounding rock; by matching with modified slurry with quick-setting early strength and underwater dispersion resistance, effective cementing and water stopping of broken surrounding rocks in a flowing water environment are realized, the water inflow of a roadway is reduced, and deformation of the surrounding rocks is controlled.

Description

Technical Field

[0001] This invention relates to the field of coal mine roadway support and water hazard prevention technology, specifically to an anchor injection water-blocking support method for water-rich fault roadways. Background Technology

[0002] During coal mining, tunnel excavation often faces complex geological conditions such as water-rich fault fracture zones. In such areas, the surrounding rock is fractured and loose, accompanied by leaching and erosion by groundwater, resulting in extremely poor mechanical properties of the surrounding rock, short self-stabilization time, and a high risk of roof collapse, spalling, or even water inrush accidents, seriously threatening the safe production of the mine.

[0003] Currently, the main treatment method for water-rich fault fracture zones is the combined anchor bolt and grouting support technology. However, in practical engineering applications, existing support techniques still have many limitations. A common practice is to adopt a "support first, grout later" approach, that is, to first perform ordinary anchor bolt support, and then perform grouting reinforcement after the tunnel has deformed to a certain extent. However, this method often lacks scientific consideration of the rheological properties of the surrounding rock, making it difficult to accurately grasp the optimal grouting time: if grouting is done too early, the surrounding rock fissures have not yet opened, and the grout cannot penetrate and diffuse; if grouting is done too late, the loosened zone of the surrounding rock has been excessively expanded or even destroyed, missing the best window for repair and reinforcement. In addition, this passive construction organization method often causes conflicts between tunneling and grouting operations, failing to effectively save tunneling time and leading to a prolonged construction period.

[0004] Another common practice, in pursuit of support strength, is to directly use grouting anchors for full-section support in roadways. While this method improves the support effect to some extent, the cost of grouting anchors and their accessories is much higher than that of ordinary anchors. The high-density arrangement across the entire section leads to a significant increase in the cost of support materials, which in turn significantly increases the mining cost of coal mines, and also results in a waste of resources in non-critical areas.

[0005] Furthermore, in water-rich environments, traditional grouting materials are mostly ordinary cement grout, which has a long setting time and poor anti-dispersion ability. Under the scouring action of flowing water, the injected grout is easily diluted or carried away by groundwater, resulting in a low grout retention rate. This makes it impossible to form an effective water-stopping curtain and solidified body, and it is difficult to fundamentally solve the problems of continuous deformation and water seepage in water-rich fault tunnels. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an anchor-grouting water-blocking support method for water-rich fault roadways. Existing water-rich fault roadway support methods suffer from problems such as high cost of full-section grouting, difficulty in accurately matching the grouting timing with surrounding rock deformation, and easy loss of ordinary grout in dynamic water environments leading to support failure.

[0007] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides a method for anchoring and water-blocking support in water-rich fault tunnels, employing the following technical solution: A method for anchor-injection water-blocking support in water-rich fault tunnels includes the following steps: Step S1: After the tunnel passes through the water-rich fault fracture zone, ordinary anchor bolts and reinforced ladder beams are constructed along with the tunneling face, and a first preload is applied to form shallow foundation support; Step S2: Within the first lag time after completing Step S1, deep reinforced anchor bolts are constructed, anchored to the deep stable rock strata, and a second preload is applied to form deep reinforced support; Step S3: Grouting anchor bolts are arranged in the area of ​​surrounding rock fissure development or at preset hole positions, and the tail of the grouting anchor bolts is sealed; Step S4: After the second lag time ends after the tunnel excavation is completed, modified cement grout is prepared and injected into the surrounding rock fissures through the grouting anchor bolts to seal them; the modified cement grout contains silicate cement, water, and composite additives.

[0008] By adopting the above technical solution, the three-level synergistic control strategy of step-by-step implementation of shallow foundation support, deep reinforcement support, and delayed grouting modification can effectively solve the support failure problem caused by the rapid expansion of the loosened zone of the surrounding rock in the water-rich fault fracture zone, softening upon contact with water, and strong rheological properties.

[0009] Specifically, the beneficial effects and mechanisms of the present invention are as follows: Spatiotemporal coordinated control mechanism: By implementing steps S1 and S2 sequentially, the shallow surrounding rock is allowed to undergo moderate stress adjustment by utilizing the first lag effect. Then, the shallow loose rock mass is suspended above the deep stable rock layer by the high prestressed deep reinforced anchor bolt, which limits the excessive expansion of the plastic zone. Delayed grouting modification mechanism: By setting a second delayed aging time in step S4, the initial stage of most severe surrounding rock deformation is avoided. Grouting is carried out when the surrounding rock fissures are fully developed and open but before collapse occurs. At this time, the grout can penetrate more smoothly into the depths of the micro-fissures, cementing the broken rock mass into a regenerated rock mass with a certain strength. This forms a coupled bearing structure with the anchor system, significantly improving the overall self-supporting capacity and impermeability of the surrounding rock. Compatibility of modified grout: Modified cement grout containing composite additives was used, and its rheological properties and setting time were adjusted for water-rich environments. This solved the problems of ordinary cement grout being easily dispersed and having a long setting time under dynamic water conditions, and achieved effective sealing and reinforcement under dynamic water conditions.

[0010] Preferably, the modified cement slurry in step S4 is made from raw materials comprising the following parts by weight: ordinary Portland cement with a strength grade of 52.5: 100 parts; water: 70 to 100 parts; composite additive: 4 to 6 parts. Preferably, the composite additive is made from components comprising the following mass percentages: aluminate clinker powder: 50% to 60%; anhydrous gypsum: 15% to 20%; calcium oxide: 10% to 15%; polyacrylamide: 1% to 3%; the balance being fly ash or silica fume; the sum of the mass percentages of all components is 100%.

[0011] By adopting the above technical solution, and utilizing the synergistic effect of specific composite additives and silicate cement systems, the grout achieves both rapid setting and early strength, as well as underwater anti-dispersion properties. The specific physicochemical reaction mechanism includes the following processes: Early-strength mineral framework construction process: When the slurry is mixed with water, the aluminate clinker powder (mainly calcium aluminate) and calcium oxide in the composite additive rapidly hydrate, releasing a large number of aluminate ions ( ) and calcium ions ( Sulfate ions provided by anhydrous gypsum () In the presence of ), a rapid reaction occurs in the liquid phase to form ettringite ( (Abbreviated as AFt). Needle-shaped ettringite crystals rapidly overlap and grow between cement particles, forming an initial spatial network framework structure with a certain strength. This structure can consume a large amount of free water (converted into crystal water), thereby shortening the initial setting time of the grout and providing high early strength to resist the surrounding rock pressure of the fault fracture zone.

[0012] Polymer flocculation and anti-dispersion process: Polyacrylamide (PAM), as a long-chain polymer, dissolves in the liquid phase of the slurry. Its active groups (such as amide groups) on the molecular chain adsorb onto the surface of cement and hydration product particles through hydrogen bonds and van der Waals forces, forming an adsorption-bridging effect. This entrapment effect flocculates cement particles into clusters, significantly increasing the cohesiveness of the slurry, effectively inhibiting the segregation and loss of cement particles in a water-rich and dynamic environment, and improving the underwater mass retention rate.

[0013] Micro-aggregate filling and densification process: Fly ash or silica fume, as active mineral admixtures, acts as micro-aggregate fillers, filling the pores between cement particles and hydration products, thus improving the density of the aggregate; on the other hand, the active silica they contain... In the later stages, it can react with calcium hydroxide produced by cement hydration. A secondary volcanic ash reaction occurs, generating hydrated calcium silicate (CSH) gel, which further enhances the later strength and impermeability of the grout-stabilized mass, ensuring the long-term stability of the support structure.

[0014] Preferably, the composite additive is prepared by the following method: aluminate clinker powder, anhydrous gypsum, and calcium oxide are ground separately and passed through a 200-300 mesh sieve; the sieved powder is then added to a dry powder mixer along with polyacrylamide and fly ash; the mixture is stirred at 30-50 r / min for 15-20 minutes at room temperature until homogeneous. By employing the above technical solution, the uniform dispersion of each component during the physical mixing stage is ensured, particularly preventing the local agglomeration of trace amounts of polyacrylamide, thus guaranteeing the performance stability of the composite additive during on-site engineering applications.

[0015] Preferably, in step S1, the ordinary anchor bolt is a left-handed threaded steel anchor bolt without longitudinal reinforcement, which is connected into a whole with the steel ladder beam; the first preload ranges from 40kN to 60kN. In step S2, the deep reinforced anchor bolt is a high-strength prestressed steel strand anchor cable, the length of which is designed to penetrate at least 1.0m to 1.5m through the fault fracture zone; the second preload ranges from 100kN to 120kN. By adopting the above technical solution, a mechanical structure of shallow flexible surface protection and deep rigid suspension is constructed. The first preload ensures that no local collapse occurs on the roadway surface, while the high-strength second preload in the deep section actively changes the stress state of the surrounding rock, increases the normal pressure and friction between the surrounding rock layers, and effectively controls the roof delamination.

[0016] Preferably, in step S2, the first lag time is 4 to 8 hours; in step S4, the second lag time is 5 to 9 days after the completion of tunnel excavation. By adopting the above technical solution, the time window for step-by-step support is precisely quantified. The first lag time of 4h to 8h: This period is in the early stage of elastic-plastic deformation of the surrounding rock. Deep reinforcement support at this time not only avoids the disturbance of the anchor cable anchorage section by blasting vibration, but also applies active restraint before harmful delamination of the surrounding rock occurs.

[0017] A second lag time of 5 to 9 days: This timeframe represents the optimal grouting window based on the rheological characteristics of the surrounding rock in water-rich fault fracture zones. If grouting occurs earlier than 5 days, the surrounding rock fissures have not fully opened, limiting the grout diffusion radius, and subsequent severe deformation can easily damage the consolidated grout veins. If grouting occurs later than 9 days, the surrounding rock may enter an accelerated creep stage, leading to instability. Grouting is performed between 5 and 9 days (preferably the 7th day), when the opening of the surrounding rock fissures is moderate, facilitating grout penetration and diffusion, repairing the damaged rock mass, and cementing the loose medium into a whole, thereby achieving the best sealing and reinforcement effect.

[0018] Preferably, in step S3, the grouting anchor bolts are hollow grouting anchor bolts, arranged in a quincunx pattern on the tunnel cross-section; the sealing length of the sealing treatment is 150mm to 200mm. In step S4, the specific process parameters for grouting and sealing are: initial grouting pressure: 0.5MPa to 1.0MPa; final grouting pressure: 2.0MPa to 3.0MPa; after the grouting pressure reaches the final grouting pressure, grouting is stopped after stabilizing the pressure for 3 to 5 minutes. By adopting the above technical solution, a variable pressure grouting process is used. The lower initial pressure is conducive to the filling of larger fractures by the grout, while the higher final pressure forces the grout to split and penetrate into micro-fractures, compacting the soil and rock mass in the grouting area. The pressure stabilization process compensates for the voids caused by grout shrinkage, ensuring grout fullness, thereby significantly reducing the water inflow in the tunnel.

[0019] Preferably, the support method further includes step S5: after grouting is completed, natural curing is carried out for 24h to 48h. By adopting the above technical solution, it is ensured that the modified cement grout is fully hydrated and reaches more than 70% of the design strength, avoiding premature bearing of mining stress that could lead to damage to the grouting body.

[0020] This invention provides a method for anchor injection and water plugging support in water-rich fault tunnels. It has the following beneficial effects: 1. This invention adopts a step-by-step implementation strategy of shallow foundation support and deep reinforcement support. After the initial surface protection structure is formed in the shallow surrounding rock, high prestressed deep reinforcement anchors are used to suspend the shallow loosened rock mass above the deep stable rock layer by constructing them within a specific lag time. This deep-shallow coupling support structure actively changes the stress state of the fractured zone surrounding rock, increases the normal pressure and friction between rock layers, effectively limits the malignant expansion of the plastic zone and the delamination of the top plate, and improves the overall self-supporting capacity of the surrounding rock.

[0021] 2. This invention precisely locks the grouting timing to 5 to 9 days (preferably the 7th day) after the completion of tunnel excavation, avoiding the initial stage when the surrounding rock deformation is most severe and the later stage when collapse is likely to occur. Within this time window, the micro-fractures in the surrounding rock are fully developed and have a suitable opening. Combined with the variable pressure grouting process, the grout can smoothly penetrate into the depth of the fractures and compact the rock mass, cementing the loose and broken media into a high-strength regenerated rock mass, thereby constructing an effective water-stopping curtain and load-bearing structure in the fault fracture zone.

[0022] 3. This invention uses a modified cement slurry containing specific composite additives. It utilizes the hydration reaction of aluminate clinker powder and calcium oxide to generate a large amount of ettringite skeleton, thereby achieving rapid setting and early strength of the slurry. At the same time, it utilizes the high molecular flocculation effect of polyacrylamide to form adsorption bridges between cement particles, which enhances the cohesiveness and anti-dispersion properties of the slurry. This formula ensures that the slurry does not segregate or run off under the condition of flowing water flushing, and can quickly block water channels, significantly reducing the residual water inflow in the roadway. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a composite additive for supporting water-rich faults. 50 kg of aluminate clinker powder, 20 kg of anhydrous gypsum, 15 kg of calcium oxide, 3 kg of polyacrylamide (anionic polyacrylamide with a molecular weight of 12 million to 15 million and a degree of hydrolysis of 20% to 25%), and 12 kg of fly ash were weighed. First, the aluminate clinker powder, anhydrous gypsum, and calcium oxide were separately ground and passed through a 200-mesh sieve. Then, the sieved powder, polyacrylamide, and fly ash were added together into a dry powder mixer. Under normal temperature and pressure, the mixer speed was set to 40 r / min, and the mixture was stirred for 20 minutes until all components were evenly dispersed. The mixture was then discharged, sealed, and packaged to obtain composite additive A.

[0025] Preparation Example 2: This preparation example provides a composite additive for supporting water-rich faults. 60 kg of aluminate clinker powder, 15 kg of anhydrous gypsum, 10 kg of calcium oxide, 1 kg of polyacrylamide, and 14 kg of fly ash were weighed. First, the aluminate clinker powder, anhydrous gypsum, and calcium oxide were ground separately and passed through a 200-mesh sieve. Then, the sieved powder, polyacrylamide, and fly ash were added together into a dry powder mixer. Under normal temperature and pressure, the mixer speed was set to 40 r / min, and the mixture was stirred for 20 minutes until all components were evenly dispersed. The mixture was then discharged, sealed, and packaged to obtain composite additive B.

[0026] Preparation Example 3: This preparation example provides a composite additive for supporting water-rich faults. 55 kg of aluminate clinker powder, 18 kg of anhydrous gypsum, 12 kg of calcium oxide, 2 kg of polyacrylamide, and 13 kg of fly ash were weighed. First, the aluminate clinker powder, anhydrous gypsum, and calcium oxide were ground separately and passed through a 200-mesh sieve. Then, the sieved powder, polyacrylamide, and fly ash were added together into a dry powder mixer. Under normal temperature and pressure, the mixer speed was set to 40 r / min, and the mixture was stirred for 20 minutes until all components were evenly dispersed. The mixture was then discharged, sealed, and packaged to obtain composite additive C.

[0027] Examples 1-3: Example 1: This embodiment provides a method for combined anchoring and injection support in roadways with water-rich fault fracture zones, including the following steps: Step 1: After the tunnel excavation passes through the water-rich fault fracture zone, the initial support construction is carried out immediately following the excavation face; first, anchor bolt holes are drilled, and left-hand threaded steel anchor bolts without longitudinal reinforcement are installed. The anchor bolt diameter is 20mm, the length is 2400mm, and the spacing between rows is set at 800mm×800mm; at the same time, steel ladder beams welded from 12mm diameter round steel and metal mesh are hung, and a preload of 50kN is applied by tightening the nuts to form the initial surface protection structure.

[0028] Step 2: Within 6 hours of completing the installation of ordinary anchor bolts, construct deep reinforcement support; drill holes in the middle of the top slab and both sides, and install high-strength prestressed steel strand anchors as reinforcement anchor bolts. The anchors have a diameter of 17.8mm, a length of 6500mm, and a spacing of 1600mm×1600mm; after installation, apply a preload of 110kN using tensioning equipment to control the top slab delamination.

[0029] Step 3: Drill holes at the designed grouting locations and arrange hollow grouting anchors in a quincunx pattern. The outer diameter of the grouting anchors is 28mm, the length is 2800mm, and the spacing between rows is 1800mm×1800mm. Use a grout stop plug to seal the holes at the ends of the anchors, with a sealing length of 180mm.

[0030] Step 4: On the 7th day after the tunnel excavation is completed (the optimal grouting time of this invention is 5 to 9 days after excavation, preferably the 7th day), delayed grouting operation shall be carried out; firstly, grouting slurry shall be prepared by weighing 100 parts of 525# ordinary Portland cement (ordinary Portland cement with a strength grade of 52.5), 80 parts of water, and 5 parts of composite additive C obtained in Preparation Example 3 according to the mass fraction; water shall be added to the mixing tank and stirring shall be started, and cement and composite additive C shall be slowly added and stirred for 4 minutes until uniform. At this time, the water-cement ratio of the slurry shall be 0.8:1; then the grouting pump shall be connected, and grouting shall be carried out on the grouting anchor bolts one hole at a time from the low point of the tunnel to the high point. The initial grouting pressure shall be controlled at 0.8MPa, and the final hole grouting pressure shall be controlled at 2.5MPa. After reaching the pressure, the pressure shall be stabilized for 4 minutes and then stopped.

[0031] Step 5: After grouting is completed, allow it to cure naturally for 36 hours until the grout has completely solidified.

[0032] Example 2: This embodiment provides a method for combined anchoring and injection support in roadways with water-rich fault fracture zones, including the following steps: Step 1: After the tunnel excavation passes through the water-rich fault fracture zone, the initial support construction is carried out immediately following the excavation face; install left-handed threaded steel anchor bolts without longitudinal reinforcement, with an anchor bolt diameter of 22mm, a length of 2000mm, and a spacing of 700mm×700mm; in conjunction with the steel ladder beams and metal mesh, apply a preload of 60kN.

[0033] Step 2: Within 4 hours of completing the installation of ordinary anchor bolts, construct deep reinforcement support; install high-strength prestressed steel strand anchor cables with a diameter of 21.6mm, a length of 6000mm, and a spacing of 1400mm×1400mm; apply a preload of 120kN after installation.

[0034] Step 3: Arrange hollow grouting anchors with an outer diameter of 32mm, a length of 2500mm, and a row spacing of 1500mm×1500mm; the tail sealing hole length is 200mm.

[0035] Step 4: Delayed grouting is carried out on the 7th day after the tunnel excavation is completed; when preparing the grout, weigh 100 parts of 525# ordinary Portland cement, 70 parts of water and 6 parts of composite additive B obtained in Preparation Example 2; mix and stir for 5 minutes, at which time the water-cement ratio of the grout is 0.7:1; carry out the grouting operation, the initial grouting pressure is 1.0MPa, considering that the surrounding rock in this area is relatively intact and requires higher pressure to penetrate the micro-fractures, the final grouting pressure is controlled at 3.0MPa, and the pressure is stabilized for 5 minutes.

[0036] Step 5: Allow to cure naturally for 24 hours after grouting is completed.

[0037] Example 3: This embodiment provides a method for combined anchoring and injection support in roadways with water-rich fault fracture zones, including the following steps: Step 1: After the tunnel excavation passes through the water-rich fault fracture zone, the initial support construction is carried out immediately following the excavation face; install left-handed threaded steel anchor bolts without longitudinal reinforcement, with an anchor bolt diameter of 20mm, a length of 2200mm, and a spacing of 750mm×750mm; in conjunction with the steel ladder beams and metal mesh, apply a preload of 40kN.

[0038] Step 2: Within 8 hours of completing the installation of ordinary anchor bolts, construct deep reinforcement support; install high-strength prestressed steel strand anchor cables with a diameter of 17.8mm, a length of 8000mm, and a row spacing of 1500mm×1500mm; apply a preload of 100kN after installation.

[0039] Step 3: Arrange hollow grouting anchors with an outer diameter of 25mm, a length of 3000mm, and a row spacing of 2000mm×2000mm; the tail sealing hole length is 150mm.

[0040] Step 4: Perform delayed grouting on the 7th day after the tunnel excavation is completed; when preparing the grout, weigh 100 parts of 525# ordinary Portland cement, 100 parts of water, and 4 parts of the composite additive A obtained in Preparation Example 1; mix and stir for 3 minutes, at which point the water-cement ratio of the grout is 1:1; carry out the grouting operation, with an initial grouting pressure of 0.5MPa. For severely fractured areas, the final grouting pressure is controlled at 2.0MPa and stabilized for 3 minutes.

[0041] Step 5: Allow grouting to cure naturally for 48 hours after completion. Comparative Examples 1-5: Compared with Example 1, Comparative Example 1 differs in that, in step four, when preparing the grout, no composite additive C was added; only 525# ordinary silicate cement and water were used for mixing and grouting. The remaining steps and parameters are the same.

[0042] Compared with Example 1, Comparative Example 2 differs in that the timing of grouting in step four is changed to be carried out immediately after the tunnel excavation is completed and the support is applied (i.e., on day 0 to 1), without reserving a period for the release of surrounding rock deformation. The remaining steps and parameters are the same.

[0043] Compared with Example 1, Comparative Example 3 differs in that the timing of grouting in step four is changed to the 15th day after the tunnel excavation is completed, at which time the loosened zone of the surrounding rock has expanded significantly. The remaining steps and parameters are the same.

[0044] Compared with Example 1, Comparative Example 4 omits step two, that is, it does not construct deep reinforcement support (high-strength prestressed steel strand anchor cable), and only relies on shallow ordinary anchor rods and grouting anchor rods to form a support system. The remaining steps and parameters are the same.

[0045] Compared with Example 1, Comparative Example 5 omits the grouting and sealing process in steps three and four, and instead constructs advanced drainage boreholes above and on both sides of the tunnel excavation face for drainage and pressure reduction treatment. The remaining support steps are the same.

[0046] Test Example 1-2: Test Example 1: Physical and Mechanical Properties and Underwater Anti-Dispersion Properties of Grouting Materials Test instructions: The modified grouting slurries prepared in Examples 1 to 3, and the pure cement slurry prepared in Comparative Example 1 were selected as test objects. Considering the characteristics of the working conditions where water-rich fault fracturing leads to severe water erosion and the surrounding rock requires rapid consolidation, the setting time, compressive strength, and underwater anti-dispersion properties of the slurries were determined according to relevant national standards.

[0047] Test items and methods: Setting time determination: According to GB / T1346-2011 "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement", the initial setting time and final setting time of the slurry were determined using a Vicat apparatus. The ambient temperature was controlled at 20℃±2℃, and the relative humidity was greater than 50%.

[0048] Compressive strength determination: According to GB / T17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)", the grout was poured into prism specimens of 40mm×40mm×160mm. Under standard curing conditions, the compressive strength was determined using a pressure testing machine at 1 day, 3 days and 28 days of age.

[0049] Underwater anti-dispersion performance test (mass retention rate method): Simulate a dynamic water environment, take a fixed amount of slurry sample (mass denoted as ). Slowly pour the solution into a graduated cylinder containing settled water, allowing it to fall freely to a certain height. After standing for 20 minutes, carefully siphon off the upper turbid liquid, collect the lower sediment of the slurry-like stone, dry it, and weigh it (recorded as ). ). Calculate the quality retention rate ( This characterizes the ability of a slurry to resist being dispersed by water flow.

[0050] Test results: The performance test data of each group of slurries are shown in the table below: Table 1: Test data of physical and mechanical properties and anti-dispersion properties of grouting materials for each group Results analysis and mechanism explanation: Based on the test data in Table 1, the mechanism of action of the technical solution in this application is analyzed as follows: The initial setting time of the slurry in Examples 1 to 3 was controlled between 18 and 34 minutes, and the final setting time was controlled within 60 minutes, significantly shorter than that of the pure cement slurry in Comparative Example 1. The mechanism lies in the fact that the aluminate clinker powder and calcium oxide components in the composite additive provide a large number of aluminate ions (…). ) and calcium ions ( In the early stages of hydration, ettringite (AFt) crystals are rapidly formed through a reaction. Needle-shaped ettringite lumps quickly overlap within the slurry to form a framework structure, consuming free water and filling pores, thus achieving rapid setting and early strength of the slurry. This characteristic ensures that the slurry quickly loses its fluidity and solidifies after injection into the fault fracture zone, preventing excessive loss of slurry along the fractures or passive water dilution.

[0051] In terms of strength, the early strength of the example group at 1 day and 3 days was significantly better than that of Comparative Example 1. In particular, Example 2 (low water-cement ratio, high admixture) achieved a 1-day compressive strength of 22.1 MPa, which is more than 3.5 times that of Comparative Example 1. The anhydrous gypsum component regulated the hydration rate of aluminate, avoiding the strength reduction caused by rapid setting. Combined with the micro-aggregate effect of fly ash, it made the stone body structure more compact, meeting the requirements for initial bearing capacity in water-rich fault support.

[0052] Regarding underwater anti-dispersion performance, the mass retention rate of the example groups remained above 85%, while that of Comparative Example 1 was only 42.3%. This is because the high molecular weight polymer polyacrylamide (PAM) in the additive played a flocculating role. The long-chain molecules of PAM form adsorption bridges between cement particles, increasing the cohesiveness of the grout and effectively inhibiting the segregation and dispersion of cement particles in a dynamic water environment. This indicates that the grouting material used in this application has good erosion resistance in a water-rich environment, ensuring the effective retention of the designed grouting volume and achieving effective filling and sealing of surrounding rock fissures.

[0053] Test Example 2: On-site monitoring and technical and economic indicator analysis of the control effect of surrounding rock in roadways Test instructions: To verify the field engineering application effect of the anchor-injection combined support method proposed in this application, a water-rich fault fracture zone roadway in a mining area with basically consistent geological conditions, fault drop, and water-rich degree was selected as the test section. The roadway was divided into several independent monitoring sections, and support operations were carried out using the construction methods described in Examples 1 to 3 and the construction methods described in Comparative Examples 2 to 5, respectively.

[0054] Monitoring content and methods: Surrounding rock deformation monitoring: A cross-point method was used, with surface displacement monitoring stations set up in each monitoring section. Laser rangefinders were used to record the convergence of the roadway roof and floor (mainly characterizing roof subsidence) and the convergence of the sidewalls. Cumulative deformation data was recorded on the 30th day after construction to evaluate the support structure's ability to control large deformations of the surrounding rock.

[0055] Water inflow monitoring: Water collection troughs and V-shaped weirs are set up in each monitoring section, and the residual water inflow in the roadway is observed and calculated regularly. The average water inflow on the 30th day after construction is recorded to evaluate the grouting sealing effect.

[0056] Comprehensive cost accounting: Calculate the material consumption (anchor bolts, cables, cement, additives), labor hours, and drainage equipment energy consumption per meter of roadway in each test section, and calculate the comprehensive support cost.

[0057] Test results: The monitoring data and economic indicators for each test section on the 30th day after construction are shown in the table below: Table 2: Statistical Table of Monitoring Data on Surrounding Rock Deformation, Water Inflow, and Comprehensive Cost of Tunnel Results analysis and mechanism explanation: Based on the monitoring data in Table 2, the implementation effects of each technical solution are compared and analyzed as follows: Regarding the timeliness mechanism of support timing (comparison of Example 1 and Comparative Examples 2 and 3): The maximum subsidence of the top plate in Example 1 was 46.2 mm, which was much lower than that in Comparative Example 2 (138.5 mm) and Comparative Example 3 (245.6 mm).

[0058] Comparative Example 2 employed an immediate excavation and grouting process. Due to the lack of a pre-determined stress release period for the surrounding rock, the grout solidified prematurely, forming a rigid shell. As the surrounding rock stress subsequently adjusted and released, the rigid grouting body could not adapt to the early, severe deformation and fractured, leading to the cracking of the sprayed layer and secondary water seepage observed in Table 2, with the water inflow rising back to 4.8 m. 3 / h.

[0059] In Comparative Example 3, grouting was delayed until 15 days later. At this time, the expansion range of the loosened zone of the surrounding rock had exceeded the grouting reinforcement range, and the rock mass structure had delamination failure. Grouting could not restore the overall strength of the rock mass, resulting in the maximum deformation.

[0060] This application (Example 1) locks in the grouting timing on the 7th day after tunneling. Utilizing the rheological properties of the surrounding rock, grouting is carried out when certain micro-fractures have formed in the shallow surrounding rock but before it becomes unstable. At this time, the fracture opening is suitable for grout penetration, and the resulting rock mass-grout vein composite structure can adapt to later rheological changes, achieving the best surrounding rock control effect.

[0061] Regarding the synergistic mechanism of combined support structures (Example 1 vs. Comparative Example 4): Comparative Example 4, lacking deep-reinforced anchor cables, experienced a top plate subsidence of 310.4 mm, 6.7 times that of Example 1. This indicates that shallow ordinary anchor bolts and grouting layers alone cannot control the expansion of the deep plastic zone in the fractured zone of a water-rich fault. This application introduces high-prestressed anchor cables (reinforced anchor bolts) to suspend the regenerated rock mass beam formed by shallow grouting reinforcement above the deep, stable bedrock, thus limiting the overall subsidence of the shallow surrounding rock and demonstrating a control mechanism of deep-shallow coupling and internal-external synergy.

[0062] Comparison between active blocking and passive drainage (Comparison of Example 1 and Comparative Example 5): Comparative Example 5 used a traditional drainage process. Although the water pressure was reduced by drainage, the residual inflow was still as high as 12.4 m³. 3 The previous method only provided water per hour, and long-term drainage increased costs to 23,500 yuan per meter. This application addresses this by actively filling water-conducting fissures with grouting anchors, cutting off the seepage channel and reducing the residual inflow to 0.8m³. 3 / h, achieving a method that primarily relies on blocking and limits emissions. Although this increases the cost of grouting materials, it reduces investment in drainage equipment and subsequent maintenance costs, resulting in an overall cost reduction of approximately 22.5% compared to traditional processes, demonstrating significant engineering and economic benefits.

Claims

1. A method for water plugging and bolting support for water-rich fault roadway, characterized in that, Includes the following steps: Step S1: After the tunnel passes through the water-rich fault fracture zone, ordinary anchor bolts and steel ladder beams are constructed along with the tunneling face, and the first pre-tightening force is applied to form shallow foundation support; Step S2: Within the first lag time after completing step S1, construct deep reinforcement anchor bolts, anchor them to the deep stable rock strata and apply a second preload to form deep reinforcement support; Step S3: Arrange grouting anchors in the area of ​​fractured surrounding rock or at the pre-set hole location, and seal the tail of the grouting anchors; Step S4: After the second lag time is completed after the tunnel excavation is finished, a modified cement grout is prepared and injected into the surrounding rock fissures through the grouting anchor bolts to seal them; The modified cement slurry contains silicate cement, water, and composite additives.

2. The water plugging and bolting support method for water-rich fault roadway according to claim 1, characterized in that, The modified cement slurry described in step S4 is made from raw materials comprising the following parts by weight: 100 parts of ordinary Portland cement with a strength grade of 52.5; Water: 70 to 100 parts; Compound additives: 4 to 6 parts.

3. The water plugging and bolting support method for water-rich fault roadway according to claim 2, characterized in that, The composite additive is made from components comprising the following mass percentages: Aluminate clinker powder: 50%–60%; Anhydrous gypsum: 15%–20%; Calcium oxide: 10%–15%; Polyacrylamide: 1%–3%; The remainder is fly ash or silica fume.

4. The water plugging and bolting support method for water-rich fault roadway according to claim 3, characterized in that, The preparation method of the composite additive includes the following steps: Aluminate clinker powder, anhydrous gypsum, and calcium oxide were ground separately and passed through a 200-300 mesh sieve. The sieved powder, polyacrylamide, and fly ash are fed into a dry powder mixer; Stir and mix at room temperature at a speed of 30 r / min to 50 r / min for 15 min to 20 min until the mixture is homogeneous.

5. The water plugging and bolting support method for water-rich fault roadway according to claim 1, characterized in that, In step S1, the ordinary anchor rod is a left-hand threaded steel anchor rod without longitudinal reinforcement, which is used in conjunction with the steel ladder beam to connect the single anchor rod into a whole; the range of the first preload is 40kN to 60kN.

6. The method for anchoring and water-blocking support in water-rich fault tunnels according to claim 1, characterized in that, In step S2, the deep-strengthened anchor bolt adopts a high-strength prestressed steel strand anchor cable, and its length is designed to pass through the fault fracture zone influence range of at least 1.0m to 1.5m; the second pre-tightening force ranges from 100kN to 120kN.

7. The anchoring and water-blocking support method for water-rich fault roadways according to claim 1, characterized in that, In step S3, the grouting anchor bolts are hollow grouting anchor bolts, which are arranged in a quincunx pattern on the roadway cross section; the sealing length of the sealing treatment is 150mm to 200mm.

8. The method for anchoring and water-blocking support in water-rich fault tunnels according to claim 1, characterized in that, In step S4, the second lag period is 5 to 9 days after the tunnel excavation is completed; The preparation process of the modified cement slurry is as follows: first, add water to the mixing container, start the stirring and slowly add the silicate cement and the composite additive, and stir for 3 to 5 minutes.

9. A method for anchoring and water-blocking support in water-rich fault tunnels according to claim 1, characterized in that, In step S4, the specific process parameters for grouting and sealing are as follows: Initial grouting pressure: 0.5MPa~1.0MPa; Final grouting pressure: 2.0 MPa~3.0 MPa; After the grouting pressure reaches the final grouting pressure, stabilize the pressure for 3 to 5 minutes and then stop grouting.

10. A method for anchoring and plugging water in water-rich fault tunnels according to claim 1, characterized in that, The support method also includes step S5: after grouting is completed, natural curing is carried out for 24h to 48h.

Images