A control composite grouting method for surface directional drilling of a water-rich fault tunnel

Abstract

The application provides a controllable composite grouting method for surface directional drilling of a water-rich fault tunnel, comprising the following steps: investigating a fault, dividing the fault into a fault zone structure composed of an influence zone, a main fault zone and a boundary zone according to the fault investigation result, and determining the risk types of the three fault zones; establishing a matching function system of the risk types and grouting core parameters; calling corresponding matching functions from the matching function system according to different risk types, and setting grouting core parameters of different risk types according to the called matching functions; and grouting according to the grouting core parameters of different risk types. The application can solve the problem of poor controllability of the existing surface directional drilling advanced grouting method.

Description

Technical Field

[0001] This invention relates to the field of surface directional drilling and advanced grouting technology for high-pressure, water-rich tunnel sections in wide fault fracture zones, and particularly to a controlled composite grouting method for surface directional drilling in water-rich fault tunnels. Background Technology

[0002] Water inrush and mudslide are core disaster risks restricting the safety, construction period, and investment of deep-buried tunnels. Wide fault fracture zones are high-risk geological formations for water inrush and mudslide disasters in deep-buried tunnels. Fault zones exhibit strong spatial heterogeneity. Based on the different formation processes and internal deformation degrees, the internal structure of faults can be divided into three core zones: the influence zone (fractured rock mass), the main fault zone (claytic debris, mylonite), and the boundary zone. The material composition, degree of fracturing, permeability, and mechanical properties of these different zones vary significantly, resulting in different types of water inrush and mudslide risks and their corresponding disaster-causing mechanisms. Advanced grouting is a core technical means for managing such risks and achieving disaster source control. Surface directional drilling advanced grouting, with its advantages of ultra-deep directional drilling, ultra-high pressure grouting, unrestricted surface construction equipment, and no impact on the main construction period, has gradually become an important means of advanced management of wide fault fracture zones in the water conservancy engineering industry.

[0003] However, existing directional drilling and pre-grouting technology suffers from poor controllability in the grouting process when dealing with wide fault fracture zones. Summary of the Invention

[0004] The purpose of this invention is to provide a controlled composite grouting method for surface directional drilling in water-rich fault tunnels, so as to solve the problems of poor grouting controllability, repeated grouting, and large grouting volume in existing surface directional drilling advance grouting methods.

[0005] To solve the above-mentioned technical problems, the present invention provides a surface directional drilling controlled composite grouting method for water-rich fault tunnels, comprising: Explore the faults and, based on the exploration results, classify the faults into a fault zone structure consisting of three types of fault zones: influence zone, main fault zone, and boundary zone, and determine the risk types of the three types of fault zones. Establish a matching function system between risk types and core grouting parameters; Based on different risk types, the corresponding matching function is called from the matching function system, and the core parameters for grouting are set according to the called matching function for different risk types; and, Grouting is performed according to the core parameters for different risk types.

[0006] Optionally, the risk types for the three fault zones—impact zone, main fault zone, and boundary zone—can be identified as follows: When the fault zone is a main fault zone, the corresponding risk type is mudslide risk; When the fault zone is a boundary zone, the corresponding risk type is compound risk; When the fault zone is an affected zone, the corresponding risk type is water inrush risk.

[0007] Optionally, the core parameters for grouting include grouting process, target grouting pressure, grouting material, and grouting section length; the matching function system includes a grouting process matching function, a target grouting pressure matching function, a grouting material matching function, and a grouting section length matching function; wherein, the grouting process matching function M(T) is: Where M(T) is the grouting process matching function, and T is the risk type; The target grouting pressure matching function P(T) is: Where P(T) is the target grouting pressure matching function, T is the risk type, and P 静 This is the hydrostatic pressure value; The grouting material matching function C(T) is: Where C(T) is the grouting material matching function, and T is the risk type; The matching function L(T) between risk type and grouting section length is: Where L(T) is the grouting section length matching function, and T is the risk type.

[0008] Optionally, the corresponding matching function can be called from the matching function system according to different risk types, and the core parameters for grouting of different risk types can be set according to the called matching function, including: Based on different risk types, the segment length matching function is called from the matching function system, and the number of segments for segmented grouting within the fault zone and the length of the single grouting segment within the corresponding segment are set according to the called segment length matching function. Based on different risk types, the grouting process matching function is called from the matching function system, and the grouting process for different risk types of broken strips is set according to the called grouting process matching function. Based on different risk types, the target grouting pressure matching function is called from the matching function system, and the target grouting pressure for different risk types of rupture zones is set according to the called target grouting pressure matching function; Based on different risk types, the matching function of the grouting material is called from the matching function system, and the grouting material for the broken strip of different risk types is set according to the grouting material matching function called.

[0009] Optionally, grouting can be performed according to the core parameters for different risk types, including: Based on the number of grouting segments within the fault zone for different risk types and the length of the single grouting segment within the corresponding segment, the first stage of grouting is carried out using the corresponding single grouting segment length and conventional cement-based grout within the corresponding number of segments until the conditions for the end of the first stage of grouting are met, at which point the first stage of grouting ends. Based on the grouting process, grouting materials, and target grouting pressure for different types of fault zones, the second stage of grouting is carried out within the corresponding number of fault zones using the corresponding single-segment grouting length until the conditions for ending the second stage of grouting are met, at which point the second stage of grouting is completed.

[0010] Optionally, the first stage of grouting adopts a step-by-step grouting technique, which includes: grouting for a first time period with a first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a second time period with a second water-cement ratio less than the first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a third time period with a third water-cement ratio less than the second water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; and then grouting is carried out step by step with a water-cement ratio less than the previous level according to the grouting time of that level until the real-time grouting pressure change is less than or equal to the grouting pressure threshold.

[0011] Optionally, the conditions for ending the first stage of grouting include: During the gradual grouting process, the water-cement ratio reaches the predetermined value, the grouting time is maintained for the predetermined duration, and the real-time grouting pressure variation remains less than or equal to the grouting pressure threshold; or... During the gradual grouting process, the real-time grouting pressure reaches the target grouting pressure of the broken zone, and the grout injection rate gradually decreases to the target flow rate and can remain stable for the target duration.

[0012] Optionally, for fault zones with a risk type of mudslide risk or combined risk, the grouting material for the second stage of grouting shall be a cement-water glass composite grout, which shall be prepared by one of the following two methods: The first method involves preparing a cement slurry with a water-cement ratio of 1.25:1 to 0.8:1, mixing it at high speed until homogeneous, and then applying it in 1m... 3 Add 10-30L of water glass to the cement slurry and continue stirring until homogeneous; The second method involves adding water, cement, and water glass in the appropriate proportions in a primary mixing tank and mixing them together until homogeneous. For fractures with a risk type of water inrush, the grouting material for the second stage of grouting is cement-based grout with a water-cement ratio of 0.6:1 to 1:1, and the initial water-cement ratio is 1:1.

[0013] Optionally, for fault zones with risk types of mudslide risk or complex risk, the second stage of grouting adopts the graded pressure increase method, that is, grouting is carried out with the first grouting flow rate, and the grouting flow rate is gradually reduced as the grouting pressure is gradually increased to the target grouting pressure of the fault zone. For fault zones with a risk type of water inrush, the second stage of grouting adopts the same step-by-step grouting technique as the first stage of grouting.

[0014] Optionally, for fault zones with risk types of mudslide risk or combined risk, and for fault zones with risk type of water inrush risk, the conditions for ending the second stage of grouting include: during the grouting process, the real-time grouting pressure reaches the target grouting pressure of the fault zone, and the grout injection rate is gradually reduced to the target flow rate and can remain stable for the target duration.

[0015] The present invention provides a surface directional drilling controlled composite grouting method for water-rich fault tunnels, which has the following beneficial effects: First, by pre-exploring and precisely delineating fault zones, the unique risk types of each fault zone are identified. A matching function system is introduced to dynamically couple risk types with grouting parameters, laying a logical foundation for subsequent precise grouting of fault zones with different risk types. This avoids the problem of "incomplete grouting in high-risk areas and over-grouting in low-risk areas" caused by neglecting fault heterogeneity, improving the targeting and effectiveness of grouting measures from the source. It provides a decision-making path for tunnels crossing faults, improves grouting controllability, and avoids ineffective waste of grouting materials, thereby reducing construction costs, shortening the construction period, and improving grouting efficiency. Addressing the significant heterogeneity of grouting characteristics within fault fracture zones—the fundamental differences in groutability, grout diffusion mechanisms, and diffusion range among fractured rock masses, fault gouge, and weak structural surfaces—this technology breaks through the extensive design mode of "single process, single material, and single pressure control standard" commonly used in existing surface directional drilling grouting technologies. It conducts a systematic and adaptable process design for the differentiated grouting characteristics of different media. This innovation effectively solves two major technical challenges in the traditional surface directional drilling high-pressure grouting process: first, the grout leaks over infinite distances along advantageous channels such as fractures and weak interfaces in the fractured rock mass; second, the grouting pressure is difficult to increase in fault gouge sections due to repeated splitting, and even repeated grouting cannot meet the design pressure requirements. Attached Figure Description

[0016] Figure 1 This is a flowchart of the surface directional drilling controlled composite grouting method for water-rich fault tunnels in this embodiment of the invention. Detailed Implementation

[0017] As described in the background section, existing directional drilling and pre-grouting technologies suffer from poor controllability during the grouting process in the treatment of wide fault fracture zones. The applicant's research revealed that the risk types of different fault zones within a fault are varying. Existing surface directional drilling grouting methods do not employ different grouting strategies for different fault zones, resulting in incomplete grouting in high-risk areas and over-grouting in low-risk areas. Ultimately, this leads to poor controllability of the grouting process, uneven grouting of different risk areas, and high grouting volume and costs.

[0018] Based on this, the applicant proposed a surface directional drilling controlled composite grouting method for water-rich fault tunnels. This method involves exploring the fault and, based on the exploration results, dividing the fault into a fault zone structure composed of three types of fault zones: influence zone, main fault zone, and boundary zone. The method then identifies the risk types of these three fault zones, establishes a matching function system between risk types and core grouting parameters, and calls the corresponding matching function from this system according to different risk types. Based on the called matching function, different core grouting parameters are set for different risk types. Finally, grouting is performed according to the different core grouting parameters for different risk types, thereby overcoming the limitations of traditional methods. The "one-size-fits-all" uniform grouting mode of surface directional drilling grouting is replaced by a new approach. By pre-exploring and precisely delineating fault zones, identifying the unique risk types of each fault zone, and introducing a matching function system to achieve dynamic coupling between risk types and grouting parameters, a logical foundation is laid for subsequent precise grouting of fault zones with different risk types. This avoids the problem of "incomplete grouting in high-risk areas and over-grouting in low-risk areas" caused by ignoring the heterogeneity of faults. It improves the targeting and effectiveness of grouting measures from the source, provides a decision-making path for tunnels crossing faults, improves the controllability of grouting, and avoids the ineffective waste of grouting materials.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but these embodiments should not be construed as limiting the present invention.

[0020] refer to Figure 1 , Figure 1 This is a flowchart of a surface directional drilling controlled composite grouting method for water-rich fault tunnels according to an embodiment of the present invention. This embodiment provides a surface directional drilling controlled composite grouting method for water-rich fault tunnels, including: Step S100: Explore the fault and, based on the fault exploration results, divide the fault into a fault zone structure consisting of three types of fault zones: influence zone, main fault zone, and boundary zone, and determine the risk type of the three types of fault zones: influence zone, main fault zone, and boundary zone. Step S200: Establish a matching function system between risk types and core grouting parameters; Step S300: Based on different risk types, the corresponding matching function is called from the matching function system, and the core grouting parameters for different risk types are set according to the called matching function; and, Step S400: Grouting is performed according to the core parameters for different risk types.

[0021] By pre-exploring and precisely delineating fault zones, identifying the unique risk types of each fault zone, and introducing a matching function system to achieve dynamic coupling between risk types and grouting parameters, a logical foundation is laid for subsequent precise grouting of fault zones with different risk types. This avoids the problem of "incomplete grouting in high-risk areas and over-grouting in low-risk areas" caused by ignoring the heterogeneity of faults, thereby improving the targeting and effectiveness of grouting measures from the source. It provides a decision-making path for tunnels crossing faults, improves grouting controllability, and avoids the ineffective waste of grouting materials caused by repeated grouting, thus reducing construction costs, effectively shortening the construction period, and improving grouting efficiency. Addressing the significant heterogeneity of grouting characteristics within fault fracture zones—the fundamental differences in groutability, grout diffusion mechanisms, and diffusion ranges among fractured rock masses, fault gouge, and weak structural surfaces—this technology breaks through the extensive design mode of "single process, single material, and single pressure control standard" commonly used in existing surface directional drilling grouting technologies. It conducts systematic adaptive process design for the differentiated grouting characteristics of different media. This innovation effectively solves two major technical challenges in the traditional surface directional drilling high-pressure grouting process: first, the grout leaks over infinite distances along advantageous channels such as fractures and weak interfaces in the fractured rock mass; second, the grouting pressure is difficult to increase in fault gouge sections due to repeated splitting, and even repeated grouting cannot meet the design pressure requirements.

[0022] The affected zone is centered on fractured rock masses, with high-pressure fissure water inrush as the main risk. The rock masses are highly permeable and have poor integrity, and the grouting characteristics are primarily infiltration-filling grouting. The main fault zone is centered on argillaceous clastic materials and mylonite, with high-pressure plastic mudslide as the main risk. The medium has fine particles, low permeability, and is easily deformable, and the grouting characteristics are primarily fracturing-compaction grouting. The boundary zone is the area where the affected zone and the main fault zone meet, possessing both water inrush and mudslide risks. Its weak points are the dominant diffusion channels for grout, and the grouting characteristics are primarily infiltration-filling combined with fracturing-compaction grouting.

[0023] Among them, the matching function system refers to the set of rules that establish a mathematical correspondence between different types of grouting risks and the most suitable grouting parameters (such as pressure, material, section length, etc.), which are used to guide differentiated grouting design.

[0024] In step S100, the risk types of the three fault zones—impact zone, main fault zone, and boundary zone—are determined as follows: When the fault zone is a main fault zone, the corresponding risk type is mudslide risk; When the fault zone is a boundary zone, the corresponding risk type is compound risk; When the fault zone is an affected zone, the corresponding risk type is water inrush risk.

[0025] Geological zones were precisely mapped to engineering hazard types. The main fault zone was clearly designated as "mud inrush risk," the affected zone as "water inrush risk," and the boundary zone as "compound risk." This ensured that subsequent grouting design moved beyond a general "water-blocking reinforcement" approach, instead providing "targeted treatment" for specific hazard mechanisms. For example, mud inrush risk focused on improving the strength and stability of the mud material itself, water inrush risk focused on blocking high-pressure water flow channels, and compound risks required a balance of both. This clear risk characterization is a crucial prerequisite for achieving controlled compound grouting, preventing treatment failures due to misjudgment of risks.

[0026] Mudslide risk refers to the risk of a large, rapid influx of loose, muddy debris from the main fault zone into the cavern under excavation unloading or groundwater dynamics, causing structural damage and equipment burial. Composite risk refers to the risk state where, within the same fault zone (the boundary between the influence zone and the main fault zone), both high-pressure water inrush and sudden mudslide threats are simultaneously present; its hazard mechanism is more complex and its prevention and control are more difficult. Water inrush risk refers to the risk within the influence zone where, due to fractured rock mass and good fissure connectivity, groundwater surges into the cavern under high pressure.

[0027] In step S200, the core parameters for grouting include grouting process, target grouting pressure, grouting material, and grouting section length; the matching function system includes grouting process matching function, target grouting pressure matching function, grouting material matching function, and grouting section length matching function. The grouting process matching function M(T) is as follows: Where M(T) is the grouting process matching function, and T is the risk type; The target grouting pressure matching function P(T) is: Where P(T) is the target grouting pressure matching function, T is the risk type, and P 静 This is the hydrostatic pressure value; The grouting material matching function C(T) is: Where C(T) is the grouting material matching function, and T is the risk type; The matching function L(T) between risk type and grouting section length is: Where L(T) is the grouting section length matching function, and T is the risk type.

[0028] This study provides, for the first time, a quantifiable mathematical basis for fault-zoned grouting. Different grouting techniques (M function), grouting pressure (P function), grouting materials (C function), and grouting section length (L function) are defined for different risk types. For example, for water inrush risk, relatively lower pressure and relatively longer section length (30-50m) are used to seal large fracture seepage channels; for mudslide risk, relatively higher pressure and relatively shorter section length (20-30m) are used to achieve a fracturing grouting effect, forming a network of grout veins. This quantitative matching relationship directly solves the problems of insufficient treatment of core areas and material waste caused by "uniform parameters" in previous technologies, achieving precise coupling between grouting parameters and geological risks.

[0029] In step S300, the corresponding matching function is called from the matching function system according to different risk types, and the core parameters for grouting of different risk types are set according to the called matching function, including: Based on different risk types, the segment length matching function is called from the matching function system, and the number of segments for segmented grouting within the fault zone and the length of the single grouting segment within the corresponding segment are set according to the called segment length matching function. Based on different risk types, the grouting process matching function is called from the matching function system, and the grouting process for different risk types of broken strips is set according to the called grouting process matching function. Based on different risk types, the target grouting pressure matching function is called from the matching function system, and the target grouting pressure for different risk types of rupture zones is set according to the called target grouting pressure matching function; Based on different risk types, the matching function of the grouting material is called from the matching function system, and the grouting material for the broken strip of different risk types is set according to the grouting material matching function called.

[0030] By calling four matching functions—segment length, process, pressure, and material—a complete grouting plan was systematically generated for each broken section. This itemized and step-by-step approach ensures that every key dimension of the grouting design (segment length, process, pressure, and material) matches the risk type, avoiding overall failure caused by optimizing a single parameter while other parameters are mismatched. This method is highly logical and operable, easy for engineers to understand and implement on-site, and is the core execution step for achieving "controlled composite grouting."

[0031] In step S400, grouting is performed according to the core parameters for different risk types, including: Step S410: Based on the number of grouting segments within the fault zone of different risk types and the length of the single grouting segment within the corresponding segment, the first stage grouting is carried out within the corresponding number of segments using the corresponding single grouting segment length and conventional cement-based grout until the end condition of the first stage grouting is met, then the first stage grouting ends. Step S420: Based on the grouting process, grouting materials, and target grouting pressure of the fracture zone with different risk types, the second stage of grouting is carried out within the corresponding number of fracture zones using the corresponding single-segment grouting length until the conditions for the end of the second stage of grouting are met, at which point the second stage of grouting is completed.

[0032] A two-stage progressive grouting process is adopted to precisely adapt to the differentiated treatment needs of different parts of the fault, simultaneously achieving the dual core objectives of water plugging and seepage prevention and surrounding rock reinforcement. This process decomposes the complex fault grouting process into two logically clear and closely connected construction steps: "filling first and then reinforcement." By controlling the grout characteristics and construction parameters in stages, the technical challenges of grouting complex fault zones are systematically solved.

[0033] The first stage is the basic framework construction stage, which uses conventional cement-based grouting materials and a unified construction strategy to quickly seal large-scale fissures and major leakage channels within the fault. This stage fully utilizes the good fluidity and diffusivity of cement-based grouting materials to ensure that the grout spreads evenly over a large area, forming a continuous and complete large-scale seepage-proof framework ring. This fundamentally controls macroscopic leakage channels and significantly reduces the risk of large-scale grout leakage and surface seepage during subsequent high-pressure grouting. At the same time, it creates relatively homogeneous geological conditions for the precise reinforcement in the second stage.

[0034] The second stage is the targeted reinforcement stage. Based on the seepage prevention framework established in the first stage, a specialized grout (cement-water glass dual-liquid grout) optimized according to the risk type is used to implement zoned and differentiated controlled grouting. This stage utilizes the controllable rapid solidification characteristics of cement-water glass grout to effectively prevent the grout from leaking and spreading excessively along weak interlayers. It solves the key technical bottleneck of difficulty in pressurizing muddy strata, ensuring that the grouting pressure can be stably increased to the design value, and achieving effective splitting, compaction, and reinforcement of fault muddy zones and fractured zones.

[0035] By constructing a matching function system for grouting core parameters that corresponds one-to-one with risk classification, the grouting method, pressure, materials, section length, and other core parameters were precisely matched according to the grouting characteristics of different zones. Combined with a two-stage progressive composite grouting process, the splitting-compaction reinforcement of mudslide and composite risk zones and the permeable filling of water inrush risk zones were achieved. This addresses the dual core needs of "water blocking and seepage prevention" and "surrounding rock reinforcement," solving the problems of unlimited grout leakage and repeated splitting along weak surfaces, difficulty in pressurizing the target formation, and ineffective grouting in surface directional drilling high-pressure grouting. The controllability of grout diffusion, formation filling fullness, surrounding rock integrity, and impermeability are all significantly improved, ensuring the stability and reliability of the grouting effect.

[0036] In step S410, the first stage of grouting adopts a step-by-step grouting technique. The step-by-step grouting technique includes: grouting for a first time period with a first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a second time period with a second water-cement ratio less than the first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a third time period with a third water-cement ratio less than the second water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; and then grouting for a third time period with a water-cement ratio less than the second water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold. Then, grouting is carried out step by step with a water-cement ratio less than the previous level according to the grouting time of that level until the real-time grouting pressure change is less than or equal to the grouting pressure threshold.

[0037] By progressively varying the grout concentration from thin to thick, and adjusting based on pressure conditions, this method maximizes the filling of fracture networks with varying apertures and connectivity. Thinner grout fills smaller fractures first, followed by thicker grout for larger ones, avoiding the problem of "small fractures not being sealed and large fractures not being adequately filled" caused by a single-concentration grout. This adaptive grouting method achieves maximum reduction in permeability of the fault fracture zone in the first stage using the most economical cement-based grout, creating optimal geological conditions for the second stage of fine grouting.

[0038] The grouting pressure threshold can be the target grouting pressure corresponding to the risk type of the fault zone.

[0039] In step S410, the conditions for the completion of the first stage grouting include: During the gradual grouting process, the water-cement ratio reaches the predetermined value, the grouting time is maintained for the predetermined duration, and the real-time grouting pressure variation remains less than or equal to the grouting pressure threshold; or... During the gradual grouting process, the real-time grouting pressure reaches the target grouting pressure of the broken zone, and the grout injection rate gradually decreases to the target flow rate and can remain stable for the target duration.

[0040] Clear and scientific criteria for terminating grouting are provided, avoiding arbitrariness based on subjective judgment. The first condition (water-cement ratio reaches maximum viscosity, pressure remains unstable), but grouting is not continued, allowing control over the grouting range and volume, avoiding waste of grouting materials. The second condition (pressure meets target and injection rate is extremely low) indicates that even if the grout concentration has not reached maximum viscosity, the formation has established sufficient impermeability. These two conditions complement each other, ensuring that the first stage of grouting can be completed in a timely manner while maintaining quality, avoiding both insufficient grouting and material waste and project delays caused by over-grouting.

[0041] For example, the step-by-step grouting technique can specifically use conventional cement-based grout, with the injection rate controlled at 250~300L / min and the initial water-cement ratio at 1.5:1. If the pressure change is less than 1MPa after continuous grouting with the 1.5:1 ratio grout for 2~4 hours, then grouting with a 1.25:1 ratio grout is used. If the pressure change is less than 1MPa after continuous grouting with the 1.25:1 ratio grout for 2~4 hours, then grouting with a 1:1 ratio grout is used. If the pressure change is less than 1MPa after continuous grouting with the 1:1 ratio grout for 4~6 hours, then grouting with a 0.8:1 ratio grout is used. If the pressure change is less than 1MPa after continuous grouting with the 0.8:1 ratio grout for 6~8 hours, then grouting with a 0.6:1 ratio grout is used. Finally, if the pressure change is less than 1MPa after continuous grouting with the 0.6:1 ratio grout for 6~8 hours, then grouting with the 0.6:1 ratio grout is used. The first stage of grouting is considered complete when the pressure change is less than 1MPa after continuous grouting with the 0.6:1 ratio grout for 6~8 hours. If, after continuous injection of 0.6:1 graded grout for 6-8 hours, the pressure variation remains less than 1 MPa, the first stage of grouting can be terminated. If, during the gradual grouting process, the target grouting pressure corresponding to the risk type of the fault zone is reached, and the grout injection rate gradually decreases to 50-60 L / (min·m) (target flow rate) and remains stable for 30 minutes (target duration), the grouting for this section can be terminated.

[0042] The water-cement ratio for grouting can reach a predetermined value of 0.6:1, the predetermined duration can be 6~8h, and the grouting pressure threshold is 1MPa.

[0043] In step S420, for fault zones with a risk type of mudslide risk or combined risk, the grouting material for the second stage of grouting is a cement-water glass composite grout, which is prepared by one of the following two methods: The first method involves preparing a cement slurry with a water-cement ratio of 1.25:1 to 0.8:1, mixing it at high speed until homogeneous, and then applying it in 1m... 3 Add 10-30L of water glass to the cement slurry and continue stirring until homogeneous; The second method involves adding water, cement, and water glass in the appropriate proportions in a primary mixing tank and mixing them together until homogeneous. For fractures with a risk type of water inrush, the grouting material for the second stage of grouting is cement-based grout with a water-cement ratio of 0.6:1 to 1:1, and the initial water-cement ratio is 1:1.

[0044] The characteristics of different grouting materials are fully utilized. For mudslide and complex risk areas, a cement-water glass composite grout is used. The core objective is to leverage its precisely controllable rapid solidification characteristics to effectively prevent the grout from leaking and spreading excessively along weak interlayers. Simultaneously, it overcomes the key technical bottleneck of pressurizing muddy strata, ensuring that the grouting pressure can be stably transmitted to the deep strata, achieving effective splitting and compaction reinforcement of muddy and fractured zones. After injection, the grout can initially set and form a mechanical framework in a very short time, quickly stabilizing loose muddy material and achieving a pressurization and reinforcement effect. For water inrush risk areas, a pure cement-based grout is used. The core objective is to quickly seal large-scale fracture channels and ensure that the grout has sufficient diffusion range to form a continuous and complete large-scale seepage barrier. The pure cement-based grout can penetrate and fill long distances along the original and tectonic fractures of the rock mass. After solidification, it forms a dense, durable, and permanent water-proof curtain, blocking the large-scale seepage path of groundwater from the source. The "segmented customization" strategy of this material is the core technology to solve the contradiction that traditional uniform materials cannot simultaneously meet the "rapid condensation requirements" and the "deep diffusion requirements".

[0045] In step S420, for fault zones with risk types of mudslide risk or compound risk, the second stage of grouting adopts the graded pressure increase method, that is, grouting is carried out with the first grouting flow rate, and the grouting flow rate is gradually reduced as the grouting pressure gradually increases to the target grouting pressure of the fault zone. For fault zones with a risk type of water inrush, the second stage of grouting adopts the same step-by-step grouting technique as the first stage of grouting.

[0046] For mudslide and complex risk zones (weak, easily disturbed strata), a "staged pressurization method" is adopted. This method involves controlling the pressure increase through "gradual flow reduction and gradual pressurization," ensuring grouting effectiveness while avoiding grout waste caused by continuous high-flow-rate injection. For water inrush risk zones (rigid fractured rock masses), the "staged variable grout method" continues to be used. This method involves "stabilizing pressure and increasing thickness" to continuously compress and fill fractures, constructing a dense seepage barrier. This differentiated choice of technology fully respects the mechanical response characteristics of different strata.

[0047] For example, the initial injection rate is controlled at 250~300L / min, that is, the first grouting flow rate is 250~300L / min. During the grouting process, a graded pressure increase method is adopted. As the grouting pressure increases step by step (0.6P→0.8P→1P, where P is the target grouting pressure), the grouting flow rate can be reduced step by step (reduced by 20~30L / min at each step). During the grouting process, the grout pressure change is monitored in real time. If grout leakage occurs along the interface zone, the grouting pressure is immediately reduced, the water glass ratio and grout concentration are adjusted, and re-grouting is carried out after 12 hours of setting.

[0048] In step S420, for fault zones with risk types of mudslide risk or composite risk, and for fault zones with risk types of water inrush risk, the conditions for ending the second stage of grouting include: during the grouting process, the real-time grouting pressure reaches the target grouting pressure of the fault zone, and the grout injection rate gradually decreases to the target flow rate and can remain stable for the target duration.

[0049] The completion of grouting is determined by a dual pressure-flow control standard. Specifically, regardless of the type of risk, the successful grouting is ultimately judged by both "pressure meeting the target" and "injection rate decreasing to the target flow rate and stabilizing." This ensures that regardless of the materials or processes used, the final reinforcement effect meets the designed impermeability and strength requirements. "Pressure meeting the target" ensures sufficient driving force, while "injection rate decreasing to the target flow rate and stabilizing" proves from the perspective of grout absorption that groutable voids in the formation have been effectively sealed or the formation strength has been sufficiently improved. This objective and quantifiable criterion effectively guides on-site construction and guarantees the final grouting quality.

[0050] For example, if during the second stage of grouting, when the target grouting pressure corresponding to the risk type of the broken zone is reached, the grout injection rate gradually decreases to 50~60L / (min·m) and remains stable for 30 minutes, the second stage of grouting can be ended.

[0051] During the construction of each grouting section, if the grouting volume in a single section is too large to reach the design pressure, the cement + water glass composite grout ratio is dynamically adjusted and the setting time is extended. Once the pressure-flow requirements are met after dynamic adjustment, the grouting of this section can be terminated. After grouting is completed, the pipeline is immediately flushed with clean water, the grouting plug is lifted to the next section, and the above construction process is repeated until the grouting work of all risk areas in the entire hole is completed.

[0052] In step S420, for fault zones with risks of mudslide or combined risks, when the second-stage grouting uses the graded pressure-increasing method, the pressure, injection rate, and grout specific gravity are monitored in real time throughout the process, with data recorded every 10 minutes, and a grouting process curve is plotted. If a sudden drop in pressure occurs, grouting is immediately stopped, the cause is analyzed, and grouting is resumed. Continuous high-flow-rate, pressureless grouting is strictly prohibited. This enhances the robustness and on-site adaptability of the grouting method.

[0053] The surface directional drilling controlled composite grouting method for water-rich fault tunnels also includes borehole design before grouting according to the core parameters of grouting for different risk types. The borehole design includes: borehole layout location design, borehole trajectory design, and borehole segmentation. The borehole layout design refers to arranging multiple boreholes circumferentially around the tunnel, with the circumferential spacing between the boreholes set according to the diffusion radius of the grout, and ensuring that the thickness of the reinforcement ring formed by the grout after grouting is greater than or equal to N times the tunnel diameter, and that the length of the borehole along the tunnel axis covers a predetermined length on both sides of the fault. The borehole trajectory design refers to making the borehole trajectory include a straight section, a directional section and a horizontal section connected in sequence, and to drill horizontally and directionally at the fault location, traversing the entire fault fracture zone along the tunnel axis. The aforementioned borehole segmentation refers to the precise division of grouting sections along the borehole axis based on the spatial distribution of the fault zone. Furthermore, the division of grouting sections needs to correspond to the number of grouting sections within the fault zone of different risk types, as well as the length of a single grouting section within the corresponding section.

[0054] The spatial arrangement of boreholes ensures the effectiveness of the grouting method. The circumferential arrangement and controlled spacing of the boreholes aim to form a continuous "barrel-shaped" reinforcement ring enveloping the tunnel, ensuring excavation safety. The borehole trajectory design ensures that surface boreholes accurately hit deep horizontal or inclined faults. Most importantly, the borehole segmentation corresponds to the aforementioned segmented grouting design within fault zones (L-function), achieving a unified approach from "spatial segmentation of boreholes" to "segmentation of grouting operations" and then to "geological risk zoning." This ensures that each grouting segment can independently and precisely serve a specific geological zone, providing the spatial basis for implementing zoned differentiated grouting.

[0055] Preferably, N is 1, and the predetermined length is determined based on the tunnel excavation diameter.

[0056] In step S100, the method for exploring faults includes adopting a three-level progressive exploration scheme of "macroscopic exploration - fine exploration - in-situ testing" to identify the core geological indicators of the target fault. The core geological indicators include spatial distribution, occurrence elements, zonal boundaries, material composition, permeability coefficient, rock mass integrity and mechanical parameters.

[0057] Through a three-tiered exploration approach—"macro-fine-in-situ"—the three core zones emphasized in the background technology can be accurately identified, and key parameters such as their boundaries, material composition, and permeability coefficient can be obtained. Therefore, this exploration method is the cornerstone of the entire "controlled composite grouting method," directly determining the accuracy of zoning and the rationality of grouting parameter settings.

[0058] Furthermore, macroscopic exploration employs magnetotellurics, fine exploration employs ground-directed core drilling, and in-situ testing employs water pressure testing and in-hole acoustic wave testing.

[0059] Magnetotelluric methods can efficiently and non-destructively perform macroscopic positioning; directional core drilling can most directly reveal the material composition and zoning structure of faults; and water pressure testing and in-hole acoustic testing can provide quantitative indicators such as permeability coefficient and integrity coefficient directly needed for grouting design. The combined application of these technologies constitutes a complete, reliable, and data-driven exploration system.

[0060] The surface directional drilling controlled composite grouting method for water-rich fault tunnels also includes, at least 7 days after the completion of grouting, a comprehensive inspection of the grouting effect is carried out through methods such as magnetotellurics, drilling inspection holes, water pressure tests, core sampling, and in-hole acoustic testing. The core testing indicators include the low resistivity zone of the formation, the permeability of the rock mass, the integrity of the core sample, and the formation wave velocity.

[0061] A complete closed-loop quality control system encompassing "design-construction-inspection" has been established. This ensures that the entire grouting method forms a traceable, evaluable, and optimizable technical chain, from "exploration and diagnosis → targeted design → precise construction → effect verification." For major water conservancy projects, this closed-loop mechanism is a core management tool for ensuring the safety of tunnels traversing fault fracture zones.

[0062] In addition, it can achieve a comprehensive evaluation of grouting effects in "multi-dimensional and multi-scale" ways.

[0063] Furthermore, the core objectives of "differentiated grouting by zone" were specifically verified. For the main fault zone (mudslide risk zone), the focus was on "core sample integrity" and "formation wave velocity" to verify whether the mud was effectively cemented and whether its strength was improved. For the influence zone (water inrush risk zone), the focus was on "rock permeability" and "low-resistivity zone" to verify whether high-pressure water inrush channels were blocked and whether the anti-seepage curtain was dense. For the boundary zone (composite risk zone), a comprehensive evaluation of four indicators was required, including permeability (water inrush prevention), core sample integrity, and wave velocity (mudslide prevention). Through this targeted verification, it is possible to clearly assess whether various differentiated designs (such as different grouting pressures, different grouting materials, and different processes) have truly achieved the expected reinforcement effect, providing valuable experimental data for parameter optimization in subsequent similar projects.

[0064] The applicant applied this scheme to a deep, water-rich fault section. The fault is approximately 700 meters deep, with a hydrostatic pressure of 6.5 MPa and a total width of 352 meters. The main fault zone is 244 meters wide (excluding the overlapping portion of the boundary zone). The boundary zone represents the contact points between the hanging wall and footwall and the main fault zone, with a width considered to be 40 meters. The influence zone of the fault between the hanging wall and footwall is 68 meters wide (excluding the overlapping portion of the boundary zone). The tectonic rocks of the main fault zone are mainly... The rock is poorly cemented, consisting of fractured rocks and fault debris with poor tectonic properties. The sonic values ​​are generally 1800 m / s to 2800 m / s. The footwall influence zone is composed of fractured Dengying Formation dolomite, with sonic values ​​generally 3000 m / s to 4500 m / s. The rock mass is broken. The hanging wall influence zone is composed of fractured Huapai Formation shale. Core samples are fragmented and thin-plate-like, with some localized original rock (shale) bedding planes visible. The sonic values ​​are generally 2000 m / s to 3000 m / s.

[0065] During the pre-grouting process of directional drilling on the fault surface, there was a problem with fractured rock mass, and it was difficult to increase the pressure even after 5-6 repeated grouting sessions. Before applying this solution, the length of each section of the grouting hole and the grouting pressure were not strictly divided according to the lithology and risk type of the fault zone. During the grouting process, the initial grouting pressure of some sections was only about 1 MPa (design grouting pressure 13-19.5 MPa). After adopting measures such as multiple re-grouting after setting, extending the setting time to more than 48 hours, increasing the injection rate, and increasing the grout concentration, the pressure increase effect was still not achieved. The effect is not obvious. Even with a single-hole, single-segment grout injection volume exceeding 60t / m, the grouting pressure is still only about 6MPa. After applying the solution in this embodiment, the grouting pressure of a single grouting hole is divided into segments and set according to lithology and risk type. After a single grouting session, the pressure increases significantly compared to the pressure before setting, reaching over 11MPa. Moreover, for most hole segments with a unit grout injection volume of around 30t / m, 1-2 re-grouting sessions can achieve a grouting pressure of 13-19.5MPa, greatly saving grouting construction time and costs.

[0066] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A surface directional drilling controlled composite grouting method for water-rich fault tunnels, characterized in that, include: Explore the faults and, based on the exploration results, classify the faults into a fault zone structure consisting of three types of fault zones: influence zone, main fault zone, and boundary zone, and determine the risk types of the three types of fault zones. Establish a matching function system between risk types and core grouting parameters; Based on different risk types, the corresponding matching function is called from the matching function system, and the core parameters for grouting of different risk types are set according to the called matching function; as well as, Grouting is performed according to the core parameters for different risk types.

2. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 1, characterized in that, The risk types of fault zones identified include: impact zone, main fault zone, and boundary zone. When the fault zone is a main fault zone, the corresponding risk type is mudslide risk; When the fault zone is a boundary zone, the corresponding risk type is compound risk; When the fault zone is an affected zone, the corresponding risk type is water inrush risk.

3. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 2, characterized in that, The core parameters for grouting include grouting process, target grouting pressure, grouting material, and grouting section length; the matching function system includes grouting process matching function, target grouting pressure matching function, grouting material matching function, and grouting section length matching function; wherein, the grouting process matching function M(T) is: Where M(T) is the grouting process matching function, and T is the risk type; The target grouting pressure matching function P(T) is: Where P(T) is the target grouting pressure matching function, T is the risk type, and P 静 This is the hydrostatic pressure value; The grouting material matching function C(T) is: Where C(T) is the grouting material matching function, and T is the risk type; The matching function L(T) between risk type and grouting section length is: Where L(T) is the grouting section length matching function, and T is the risk type.

4. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 3, characterized in that, Based on different risk types, the corresponding matching function is called from the matching function system, and the core parameters for grouting of different risk types are set according to the called matching function, including: Based on different risk types, the segment length matching function is called from the matching function system, and the number of segments for segmented grouting within the fault zone and the length of the single grouting segment within the corresponding segment are set according to the called segment length matching function. Based on different risk types, the grouting process matching function is called from the matching function system, and the grouting process for different risk types of broken strips is set according to the called grouting process matching function. Based on different risk types, the target grouting pressure matching function is called from the matching function system, and the target grouting pressure for different risk types of rupture zones is set according to the called target grouting pressure matching function; Based on different risk types, the matching function of the grouting material is called from the matching function system, and the grouting material for the broken strip of different risk types is set according to the grouting material matching function called.

5. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 4, characterized in that, Grouting is performed based on the core parameters for different risk types, including: Based on the number of grouting segments within the fault zone for different risk types and the length of the single grouting segment within the corresponding segment, the first stage of grouting is carried out using the corresponding single grouting segment length and conventional cement-based grout within the corresponding number of segments until the conditions for the end of the first stage of grouting are met, at which point the first stage of grouting ends. Based on the grouting process, grouting materials, and target grouting pressure for different types of fault zones, the second stage of grouting is carried out within the corresponding number of fault zones using the corresponding single-segment grouting length until the conditions for ending the second stage of grouting are met, at which point the second stage of grouting is completed.

6. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 5, characterized in that, The first stage of grouting employs a progressively variable grouting technique, which includes: grouting for a first time period with a first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a second time period with a second water-cement ratio less than the first water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; then grouting for a third time period with a third water-cement ratio less than the second water-cement ratio until the real-time grouting pressure change is less than or equal to the grouting pressure threshold; and so on, grouting is performed step by step with a water-cement ratio less than the previous level and according to the grouting time of that level until the real-time grouting pressure change is less than or equal to the grouting pressure threshold.

7. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 6, characterized in that, The conditions for the completion of the first stage of grouting include: During the gradual grouting process, the water-cement ratio reaches the predetermined value, the grouting time is maintained for the predetermined duration, and the real-time grouting pressure variation remains less than or equal to the grouting pressure threshold; or... During the gradual grouting process, the real-time grouting pressure reaches the target grouting pressure of the broken zone, and the grout injection rate gradually decreases to the target flow rate and can remain stable for the target duration.

8. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 7, characterized in that, For fault zones with risks classified as mudslide risk or combined risk, the grouting material for the second stage of grouting is a cement-water glass composite grout, which is prepared using one of the following two methods: The first method involves preparing a cement slurry with a water-cement ratio of 1.25:1 to 0.8:1, mixing it at high speed until homogeneous, and then applying it in 1m... 3 Add 10-30L of water glass to the cement slurry and continue stirring until homogeneous; The second method involves adding water, cement, and water glass in the appropriate proportions in a primary mixing tank and mixing them together until homogeneous. For fractures with a risk type of water inrush, the grouting material for the second stage of grouting is cement-based grout with a water-cement ratio of 0.6:1 to 1:1, and the initial water-cement ratio is 1:

1.

9. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 8, characterized in that, For fault zones with risks of mudslide or combined risks, the second stage of grouting adopts the graded pressure increase method, that is, grouting is carried out with the first grouting flow rate, and the grouting flow rate is gradually reduced as the grouting pressure is gradually increased to the target grouting pressure of the fault zone. For fault zones with a risk type of water inrush, the second stage of grouting adopts the same step-by-step grouting technique as the first stage of grouting.

10. The surface directional drilling controlled composite grouting method for water-rich fault tunnels as described in claim 9, characterized in that, For fault zones with risk types of mudslide risk or combined risk, and for fault zones with risk type of water inrush risk, the conditions for ending the second stage of grouting include: during the grouting process, the real-time grouting pressure reaches the target grouting pressure of the fault zone, and the grout injection rate is gradually reduced to the target flow rate and can remain stable for the target duration.

Images