Supporting method for high-stress and large-dip-angle soft rock roadway of deep well

Abstract

The invention discloses a supporting method for a deep well high-stress and large-dip-angle soft rock roadway, and particularly relates to the field of mine engineering.The supporting method comprises the steps that physical and mechanical parameters, crustal stress distribution and hydrological conditions of roadway surrounding rock are analyzed, and soft rock creep characteristics and an asymmetric deformation mechanism are recognized; steel wire ropes are adopted as ribs and matched with sprayed concrete to form a seal coat; anchoring and grouting are combined through the novel hollow grouting anchor rod; a pressure relief groove is formed in a stress concentration area, the local stress concentration effect of the surrounding rock is reduced, and stress regulation and control are achieved together with bolting and grouting; through roadway separation monitoring, surrounding rock surface displacement monitoring and anchor rod stress monitoring, the surrounding rock state is mastered in real time, support parameters are adjusted according to feedback data, and roadway instability is avoided. According to the method, supporting parameters are regulated and controlled through trial, surrounding rock top plate sinking, bottom plate bulging and side convergence are controlled, and roadway instability is avoided.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, and more specifically, to a support method for deep, high-stress, and steeply inclined soft rock roadways. Background Technology

[0002] As the depth of coal mining in my country continues to increase, coal mining is gradually advancing to depths of thousands of meters. Deep mining roadways generally suffer from problems such as high ground stress, large rock dip angles, high clay cement content, and severe softening upon contact with water, resulting in the surrounding rock exhibiting large deformation and failure characteristics of "continuous rheology and asymmetric displacement".

[0003] Existing literature 1 (Research and Application of Support Technology for Deep Soft Rock Roadways, 2020) proposes a composite support structure of "U36 steel shed + shotcrete sealing + anchor beam + backwall and floor grouting". This composite support structure is a combined reinforcement scheme for deep soft rock roadways. It utilizes a U36 steel shed to form an integral skeleton, and the inner side of the shed is sealed by shotcrete to enhance the integrity and deformation resistance of the roadway surface. On this basis, anchor beams are installed to effectively interlock the steel shed with the surrounding rock, further improving the load-bearing capacity and stability of the structure. At the same time, grouting reinforcement is implemented behind the roadway wall and floor to improve the bonding between sandy mudstone and sandstone layers and enhance the floor's resistance to heave. Through this multi-factor synergistic approach, comprehensive control of roof settlement, floor heave, and sidewall convergence is achieved. However, the composite support structure does not adequately consider the long-term rheological properties and asymmetric failure of deep soft rock.

[0004] Existing public literature 2 (Research and Application of Strong One-Time Support Technology for Deep Well Soft Rock Roadways, 2022) proposes a strong one-time support scheme. This scheme optimizes the roadway cross-section from a semi-circular arch to a rectangular cross-section, eliminating the traditional scaffolding support. It employs initial shotcrete (50mm) combined with anchor cables for foundation reinforcement, and adds high-strength anchor cable support across the entire cross-section. Grouting anchor cables are also placed in the roof, sides, and floor. The plastic failure zone is fully reinforced through alternating deep and shallow grouting. Secondary tightening after grouting ensures long-term stability, ultimately forming a composite load-bearing structure of "shotcrete layer + full anchor cable + full-section grouting," significantly improving the bearing capacity of the shallow surrounding rock in the roadway. Although field monitoring results show that deformation is effectively controlled in the short term, the stability during long-term service still requires further investigation.

[0005] Therefore, there is an urgent need for a support method that can adjust support parameters in real time to control roof subsidence, floor bulging, and sidewall convergence asymmetric deformation, while avoiding roadway instability. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of existing technologies, this invention provides a support method for deep wells with high stress and steeply inclined soft rock tunnels. This method utilizes wire ropes and sprayed layers to construct a closed structure, mitigating uneven deformation and crack propagation in the surrounding rock. Combined anchoring and grouting support organically integrates anchoring and grouting, enhancing the bearing capacity and long-term stability of the surrounding rock. Furthermore, a parametric dynamic control model is proposed, incorporating multi-dimensional monitoring and feedback of roof delamination, surface displacement, and anchor bolt stress. This model allows for real-time adjustment of support parameters, controlling asymmetric deformations such as roof subsidence, floor bulging, and sidewall convergence, thereby addressing the problems mentioned in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A support method for deep wells with high stress and steep inclination soft rock tunnels includes the following steps: S1 analyzes the physical and mechanical parameters, geostress distribution, and hydrological conditions of the surrounding rock of the tunnel to identify the creep characteristics and asymmetric deformation mechanism of soft rock. S2 uses steel wire rope as reinforcement, combined with shotcrete to form a sealing layer; S3 combines anchoring and grouting through a new type of hollow grouting anchor. S4, stress relief grooves are arranged in the stress concentration area to reduce the local stress concentration effect of the surrounding rock and achieve stress regulation together with anchor injection; S5 monitors the surrounding rock condition in real time through roadway delamination monitoring, surrounding rock surface displacement monitoring, and anchor bolt stress monitoring, and adjusts support parameters based on feedback data to prevent roadway instability. In step S5, based on data from the roof delamination gauge, surface displacement gauge, and anchor stress sensor, a parametric dynamic control model is proposed to identify the trends of roof subsidence and floor heave, including the following steps: S51 performs time-series alignment, anomaly suppression, and feature mapping on sensor data; S52, Identify the deformation stage of the tunnel; S53, predict the amount of roof subsidence and floor heave deformation in the roadway; S54. The predicted subsidence of the top plate and the deformation of the bottom heave are compared with the set target control range. If the prediction exceeds the limit, measures are taken in sequence to increase the pre-tightening force of the anchor bolts, thicken the shotcrete layer, shorten the grouting section length, increase the grouting pressure, and densify the anchor bolt arrangement. The densified anchor bolt arrangement is used in conjunction with the steel fiber spray layer to focus on reinforcing the crack area. After the reinforcement is completed, the cracks and the displacement of the top arch are continuously monitored. If they still develop, short-segment grouting is carried out to reduce the deformation rate of the top plate and the bottom heave.

[0008] As a further aspect of this invention, S1, the physical and mechanical parameters, stress distribution, and hydrological conditions of the surrounding rock of the tunnel are analyzed to identify the creep characteristics and asymmetric deformation mechanism of soft rock, including the following specific contents: After the tunnel excavation is completed, the surrounding rock, which was originally in a state of three-dimensional stress equilibrium, rapidly becomes unbalanced due to pressure relief. The roof and floor exhibit a significant convergence effect, and the sides also converge towards the tunnel space. This characteristic of high initial deformation speed and rapid amplitude exceeds the bearing capacity of conventional support. Subsequently, it enters a long-term creep stage, and the deformation rate of the surrounding rock gradually slows down. However, due to the significant rheological properties of the deep soft rock itself, the internal structure continues to deform slowly under the coupling effect of high stress and time effect, leading to a gradual deterioration of the tunnel stability. In addition, deep soft rock tunnels also exhibit high sensitivity to dynamic load disturbances. When adjacent mining activities generate mining stress, blasting operations bring vibration and impact, or the roof is softened by water erosion, the stability of the surrounding rock decreases significantly. This often results in the expansion of existing cracks, rapid roof subsidence, and severe floor heave, accelerating the failure process.

[0009] As a further aspect of the present invention, S2, a sealing layer is formed using steel wire ropes as reinforcement and shotcrete, including the following specific details: In the control of surrounding rock in deep, high-stress, and steeply inclined soft rock tunnels, the purpose of constructing a sealing layer is to form a composite layer structure to resist the damage of the surrounding rock under high ground stress, mining disturbance, and impact loads. The sealing layer adopts a dual construction mode of "inner skeleton + outer shotcrete layer". The inner layer is arranged with a steel wire rope mesh as the "skeleton" structure, which bears the tensile and elongation functions. The outer layer is constructed using multi-layer shotcrete, with each layer controlled to a thickness of 5 to 8 centimeters, and a total thickness of not less than 80 millimeters. The design of the dual construction mode ensures that the sealing layer has "dual attributes" in terms of mechanical properties: on the one hand, it has high-strength rigidity, which can exert a strong constraint on the surrounding rock and prevent it from undergoing large-scale overall damage; on the other hand, it has high-toughness flexibility, which can absorb impact energy and allow the surrounding rock to undergo slow deformation within a certain range, thereby avoiding brittle instability induced by stress concentration.

[0010] Immediately after tunnel excavation, initial rock bolt support is implemented to ensure the initial stability of the surrounding rock. Subsequently, steel wire rope reinforcement is promptly laid and evenly fixed to the tunnel cross-section, with a spacing controlled between 200 and 300 mm. After the reinforcement is in place, layered shotcrete construction begins, employing a wet spraying process. Layered spraying not only ensures uniform thickness and progressive compaction of the sprayed layer but also effectively reduces quality problems such as segregation and cracking caused by excessive thickness in a single layer. After multiple layers of spraying are completed, the overall thickness of the sprayed layer is no less than 80 mm. After construction, the sprayed surface is moistened for 7 days to prevent cracks caused by early water loss and shrinkage, ensuring that the sprayed layer forms a uniform, dense, and stable structure during the hardening process.

[0011] As a further aspect of the present invention, S3 combines anchoring and grouting through a novel hollow grouting anchor rod, including the following specific aspects: From the perspective of grouting principles, the movement of grout under pressure can be divided into three stages. In the compaction stage, the grout is forced into the surrounding rock fissures, gradually closing the existing fissures, reducing the porosity of the surrounding rock, and increasing the overall density. In the splitting stage, when the grouting pressure exceeds the local tensile strength of the rock mass, the grout will extend along the weak surface or potential splitting surface, further extending the fissure range and filling it, thereby increasing the grouting coverage area. In the passive blocking stage, as the grout gradually solidifies, the surrounding rock fissures are effectively blocked, and the grout forms a dense cementitious body, preventing water infiltration and further fissure expansion. Through this process, grouting not only achieves reinforcement and filling of the surrounding rock fissures but also improves the overall mechanical properties of the rock mass, increasing its compressive strength and deformation modulus. Especially in the roof, sides and floor of steeply inclined coal seams, where fissures are well-developed and severely affected by water hazards, grouting can play a key role in enhancing the integrity of the surrounding rock and provide a reliable "second line of defense" for anchors.

[0012] From the perspective of the anchoring mechanism, the core of combining anchoring and grouting lies in the combined effect of "anchor restraint + grout reinforcement". The anchor itself provides axial restraint through end anchoring and full-length bonding, preventing excessive displacement of the free surface of the surrounding rock and placing the surrounding rock in a triaxial stress state. At the same time, after solidification, the grout not only fills and cements the cracks, but also increases the cohesion and friction angle of the surrounding rock, which means that the ultimate bearing capacity of the surrounding rock under the Mohr-Coulomb strength criterion is improved. When the anchor and grout work together, the surrounding rock, anchor, and grout form a "composite" structure similar to reinforced concrete: the anchor is similar to the steel bars in concrete, bearing the main tensile force; the grout solidification body is similar to the concrete matrix, bearing the overall compressive force and transmitting force of the surrounding rock; after the two are coupled, the support system has higher bearing capacity and long-term stability. The advantage of this "composite reinforcement" method is that even if the surrounding rock is locally weakened or cracked, the anchor bolts and grouting body can still ensure the transmission of force and overall stability, thus avoiding the limitation of traditional single anchor bolt support being prone to failure in high-stress soft rock environments.

[0013] The anchor bolts should be at least 2.5 meters long, with a spacing of approximately 0.9 meters. Secondly, the anchor cables, as deep confinement elements, should be at least 5.5 meters long, with a spacing of 1.8 meters. The grouting pressure should be controlled between 6 and 8 MPa; the grout diffusion radius should be controlled to be above 1.5 meters. Furthermore, the pull-out force of a single anchor bolt should be no less than 228 kN.

[0014] As a further aspect of the present invention, S4, stress relief grooves are arranged in the stress concentration area to reduce the local stress concentration effect of the surrounding rock, and stress regulation is achieved together with anchoring and grouting. This includes the following specific aspects: In the stress concentration area of ​​the roadway, local stress peaks occur, and the roadway stress concentration area is easily disturbed and becomes the starting point of failure. By arranging stress relief grooves in the roadway stress concentration area, slight deformation or directional crack propagation occurs in the local rock mass, thereby actively releasing some of the stress concentration and reducing the potential risk of dynamic failure. The stress relief measures work synergistically with the sealing layer and integrated anchoring and grouting support. The sealing layer provides comprehensive protection with both rigidity and flexibility, and has overall impact resistance when subjected to external pressure; the integrated anchoring and grouting forms a composite load-bearing structure through anchoring and grouting, improving the overall strength and toughness of the surrounding rock. Based on this, the stress relief measures further optimize the stress environment, reduce the sudden failure of the surrounding rock under high ground stress, and enable the strong and tough sealing layer and anchoring and grouting system to function in a more uniform stress field.

[0015] As a further aspect of the present invention, S5, by monitoring roadway delamination, surrounding rock surface displacement, and anchor bolt stress, the surrounding rock condition is monitored in real time, and support parameters are adjusted based on feedback data to prevent roadway instability. This includes the following specific aspects: installing roof delamination gauges in the roadway to monitor the stratification displacement between different rock layers in the roof; installing surface displacement gauges on the sidewalls and floor to detect the overall convergence and floor heave of the roadway cross-section; and installing stress sensors on key load-bearing anchor bolts to monitor the anchor bolt stress state in real time, thereby determining the reliability of the anchoring system and preventing secondary damage caused by anchor bolt prestress attenuation or support failure.

[0016] The technical effects and advantages of this invention for a support method in deep, high-stress, and steeply inclined soft rock tunnels are as follows: This invention employs a multi-element collaborative design of "steel wire rope reinforcement + shotcrete sealing layer + hollow grouting anchor bolts + pressure relief grooves + dynamic monitoring and control." On one hand, the steel wire rope and shotcrete layer construct an overall closed structure, improving the tensile and impact resistance of the surrounding rock and mitigating uneven deformation and crack propagation. On the other hand, the combined anchoring and grouting support organically integrates anchoring and grouting, constructing a composite structure similar to reinforced concrete, significantly enhancing the bearing capacity and long-term stability of the surrounding rock. Simultaneously, pressure relief grooves are placed in stress concentration areas to actively release local stress and prevent sudden instability. Finally, combined with multi-dimensional monitoring and feedback of roof delamination, surface displacement, and anchor bolt stress, along with robust Bayesian fusion and dynamic prediction models, the rolling optimization and real-time control of support parameters are achieved. This method not only effectively controls asymmetric deformations such as roof subsidence, floor bulging, and sidewall convergence, but also takes into account both short-term strength and long-term creep control, significantly improving the overall stability and service life of the roadway. Compared with existing technologies, it is more adaptable and reliable under complex conditions of deep soft rock. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a support method for deep wells with high stress and steep inclination soft rock tunnels according to the present invention.

[0018] Figure 2 This is a schematic diagram of the stress distribution in the surrounding rock of a steeply inclined rock stratum tunnel according to the present invention.

[0019] Figure 3 This is a diagram showing the stress and fracturing surface in the rock mass of this invention.

[0020] Figure 4 This is the rock mass fracture mechanics model of the present invention.

[0021] Figure 5 This is a schematic diagram of the tunnel delamination monitoring, surrounding rock surface displacement monitoring, and anchor bolt stress monitoring of the present invention.

[0022] In the picture: For the maximum principal stress, For minimum principal stress, For normal stress, This is shear stress. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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] Example 1. The present invention provides a support method for deep well high-stress and steeply inclined soft rock tunnels, comprising the following steps: S1 analyzes the physical and mechanical parameters, geostress distribution, and hydrological conditions of the surrounding rock of the tunnel to identify the creep characteristics and asymmetric deformation mechanism of soft rock.

[0025] S2 uses steel wire rope as a framework, combined with sprayed concrete to form a sealing layer.

[0026] S3 combines anchoring and grouting through a new type of hollow grouting anchor.

[0027] S4, stress relief grooves are arranged in the stress concentration area to reduce the local stress concentration effect of the surrounding rock, and together with the anchor injection, stress regulation is achieved.

[0028] S5 monitors the surrounding rock condition in real time through roadway delamination monitoring, surrounding rock surface displacement monitoring, and anchor bolt stress monitoring. Based on the feedback data, it adjusts the support parameters to prevent roadway instability.

[0029] Further, in S1, the physical and mechanical parameters, stress distribution, and hydrological conditions of the surrounding rock of the roadway are analyzed to identify the creep characteristics and asymmetric deformation mechanism of soft rock. This includes: In this embodiment, under the actual engineering background of the Shanxian Energy 8301 Jiaoshun Yard, the roadway is buried at a depth of over 1000 meters, located in the mudstone roof of the No. 3 coal seam. The geological conditions are complex and unfavorable for the long-term stability of the surrounding rock. The No. 3 coal seam has a dip angle between 23° and 36°, averaging about 30°, and is a typical steeply dipped coal seam. Affected by gravity and the superposition effect of bedding direction, the stress distribution of the surrounding rock exhibits significant asymmetry. The roof is mainly composed of mudstone and siltstone, which is easily softened and decomposed upon contact with water, thus significantly reducing the bearing capacity and overall stability, leading to an increased risk of roof collapse. The floor is mainly composed of fine sandstone with obvious fissures, which easily become stress concentration areas under deep, high-stress environments, exacerbating the floor bulging phenomenon. The tunnel cross-section is designed as a straight-walled semi-circular arch with a net width of 5.0 meters and a net height of 4.0 meters. Although the cross-section structure facilitates excavation and initial support, the uneven stress on the two sides of the straight wall, coupled with the concentrated pressure on the arch crown, results in insufficient overall deformation resistance, leading to rapid instability of the surrounding rock under dynamic pressure and mining disturbance.

[0030] After the tunnel excavation was completed, the surrounding rock, which was originally in a state of three-dimensional stress equilibrium, rapidly became unbalanced due to pressure relief. A significant convergence effect occurred between the roof and floor, and the sidewalls also converged into the tunnel space. This characteristic of high initial deformation rate and rapid amplitude exceeded the bearing capacity of conventional support. Subsequently, a long-term creep stage began, during which the deformation rate of the surrounding rock gradually slowed down. However, due to the significant rheological properties of the deep soft rock itself, the internal structure continued to deform slowly under the coupled effect of high stress and time, leading to a gradual deterioration of tunnel stability. Figure 2 As shown, due to the large dip angle of the coal and rock strata, the gravitational component acts along the bedding direction, resulting in a spatial distribution of stress concentration and stress release at the four corners of the roadway cross-section. At the two corners of the stress concentration zone, the surrounding rock is prone to significant shearing and slippage, leading to large-scale spalling of the sidewalls. Conversely, the stress release zone remains relatively stable, resulting in significant asymmetric displacement. This asymmetric failure not only alters the force balance of the roadway cross-section but also increases the complexity of the support design. Furthermore, deep soft rock roadways exhibit high sensitivity to dynamic load disturbances. When adjacent mining activities generate mining-induced stress, blasting operations bring vibration and impact, or the roof is softened by water erosion, the stability of the surrounding rock decreases significantly. This often leads to the expansion of existing fissures, rapid roof subsidence, and severe floor heave, accelerating the failure process.

[0031] Furthermore, in S2, a sealing layer is formed using steel wire ropes as the framework, combined with shotcrete. This includes: in the control of surrounding rock in deep, high-stress, and steeply inclined soft rock tunnels, the purpose of constructing the sealing layer is to form a composite layer structure to resist the damage of the surrounding rock under high ground stress, mining disturbance, and impact loads. The sealing layer adopts a dual construction mode of "inner framework + outer shotcrete layer". The inner layer is arranged with a steel wire rope mesh as the "framework" structure, bearing the tensile and ductile functions. Due to the high tensile strength and good ductility of the steel wire rope, it can provide flexible restraint and ductile release when the surrounding rock undergoes uneven deformation, avoiding cracking and spalling caused by local stress concentration; at the same time, the steel wire rope is tightly integrated with the outer shotcrete layer, which can connect the dispersed surrounding rock fragments with the shotcrete layer as a whole, forming a relatively strong "composite framework". The outer layer is constructed using multi-layer shotcrete, with each layer controlled to a thickness of 5 to 8 cm, and a total thickness of not less than 80 mm. The addition of functional admixtures such as early-strength agents, water-reducing agents, and crack-resistant fibers to the shotcrete ensures the early strength development rate of the concrete and reduces shrinkage cracking caused by excessive water-cement ratio. The addition of crack-resistant fibers significantly improves the tensile strength and toughness of the sprayed layer, enabling it to withstand high pressure under stress while also possessing a certain degree of deformation capacity, preventing overall brittle fracture due to localized stress overload. This dual-structure design ensures the sealing layer possesses "dual attributes" in mechanical properties: on the one hand, it exhibits high-strength rigidity, providing strong constraint on the surrounding rock and preventing large-scale overall failure; on the other hand, it possesses high-toughness flexibility, absorbing impact energy and allowing slow deformation of the surrounding rock within a certain range, thereby avoiding brittle instability induced by stress concentration.

[0032] Immediately after tunnel excavation, initial anchor bolt support is implemented to ensure the initial stability of the surrounding rock. Subsequently, steel wire rope reinforcement is promptly deployed and evenly fixed to the tunnel cross-section, with a spacing controlled at 200 to 300 mm to ensure that the wire ropes fully cover the cross-section and form an integral load-bearing system with the shotcrete layer. After the reinforcement is in place, layered shotcrete construction begins, employing a wet spraying process to improve the density and adhesion of the shotcrete layer. Layered spraying not only ensures uniform thickness and progressive compaction of the shotcrete layer but also effectively reduces quality problems such as segregation and cracking caused by excessive thickness of a single layer. After multiple layers of spraying are completed, the overall shotcrete layer thickness is not less than 80 mm. After construction, the shotcrete surface is moistened for 7 days to prevent cracks caused by early water loss and shrinkage, ensuring that the shotcrete layer forms a uniform, dense, and stable structure during the hardening process.

[0033] Furthermore, S3 combines anchoring and grouting through a novel hollow grouting anchor bolt, including: the principle of combining anchoring and grouting is to achieve multi-scale joint reinforcement of "point-line-surface" through the synergistic effect of anchoring and grouting: the anchor bolt and anchor cable, as linear constraint units, directly control the displacement trend of the surrounding rock; the grouting slurry solidifies into a network cement in the surrounding rock fissures, playing a role in surface reinforcement and filling; after the two are combined, an overall reinforcement system with both strength and toughness is constructed.

[0034] From the perspective of grouting principles, the movement of grout under pressure can be divided into three stages, such as... Figure 3 and Figure 4 As shown, during the compaction stage, the grout is forced into the surrounding rock fissures, gradually closing existing fissures, reducing the porosity of the surrounding rock, and increasing the overall density. During the splitting stage, when the grouting pressure exceeds the local tensile strength of the rock mass, the grout extends along weak or potential splitting surfaces, further extending and filling the fissures, thus increasing the grout coverage area. During the passive blocking stage, as the grout gradually solidifies, the surrounding rock fissures are effectively blocked, and the grout forms a dense cementitious body, preventing water infiltration and further fissure expansion. Through this process, grouting not only reinforces and fills the surrounding rock fissures but also improves the overall mechanical properties of the rock mass, increasing its compressive strength and deformation modulus. Especially in the roof, sides, and floor of steeply inclined coal seams, where fissures are well-developed and severely affected by water hazards, grouting plays a crucial role in enhancing the integrity of the surrounding rock, providing a reliable "second line of defense" for anchors.

[0035] From the perspective of the anchoring mechanism, the core of combining anchoring and grouting lies in the combined effect of "anchor restraint + grout reinforcement". The anchor itself provides axial restraint through end anchoring and full-length bonding, preventing excessive displacement of the free surface of the surrounding rock and placing the surrounding rock in a triaxial stress state. At the same time, after solidification, the grout not only fills and cements the cracks, but also increases the cohesion and friction angle of the surrounding rock, which means that the ultimate bearing capacity of the surrounding rock under the Mohr-Coulomb strength criterion is improved. When the anchor and grout work together, the surrounding rock, anchor, and grout form a "composite" structure similar to reinforced concrete: the anchor is similar to the steel bars in concrete, bearing the main tensile force; the grout solidification body is similar to the concrete matrix, bearing the overall compressive force and transmitting force of the surrounding rock; after the two are coupled, the support system has higher bearing capacity and long-term stability. The advantage of this "composite reinforcement" method is that even if the surrounding rock is locally weakened or cracked, the anchor bolts and grouting body can still ensure the transmission of force and overall stability, thus avoiding the limitation of traditional single anchor bolt support being prone to failure in high-stress soft rock environments.

[0036] The anchor bolts are at least 2.5 meters long, with a spacing of approximately 0.9 meters. This parameter ensures effective reinforcement of the shallow surrounding rock, preventing spalling and scabbing of the roof and sides. Secondly, the anchor cables, as deep restraint elements, are at least 5.5 meters long and spaced 1.8 meters apart, used to control the stability of the surrounding rock in deeper areas, forming a dual-layer control system for both shallow and deep sections. The grouting pressure is controlled between 6 and 8 MPa. This pressure ensures effective grout penetration into the fractures while preventing excessive pressure from creating new fracture surfaces in the surrounding rock. The grout diffusion radius is controlled at over 1.5 meters to ensure sufficient overlap of the grout between adjacent anchor bolts, forming a continuous mesh-like reinforced structure. Furthermore, the pull-out force of a single anchor bolt is at least 228 kN to ensure sufficient pull-out resistance, effectively restraining surrounding rock displacement even under high ground stress conditions.

[0037] Furthermore, in S4, stress relief grooves are arranged in stress concentration areas to reduce the local stress concentration effect of the surrounding rock. This, combined with grouting, achieves stress regulation. Specifically, in stress concentration areas of the roadway, such as the roof arch corners and the lower sidewalls of the floor, local stress peaks occur. These stress concentration areas are highly susceptible to becoming the starting point of failure once disturbed. By arranging stress relief grooves in these areas, slight deformation or directional crack propagation occurs in the local rock mass, thereby actively releasing some of the stress concentration and reducing the potential risk of dynamic damage. Its working principle is similar to the buffer mechanism of "pre-splitting blasting," that is, by artificially guiding the surrounding rock to release energy in advance, it avoids sudden large-scale instability under mining disturbances or mining-induced effects. The stress relief measures work synergistically with the sealing layer and integrated grouting support. The sealing layer provides comprehensive protection with both rigidity and flexibility, possessing overall impact resistance when subjected to external pressure; the integrated grouting support forms a composite load-bearing structure through anchoring and grouting, improving the overall strength and toughness of the surrounding rock. The pressure relief measures further optimized the stress environment, reduced the sudden failure of the surrounding rock under high ground stress, and enabled the strong and tough sealing layer and anchoring system to play a role in a more uniform stress field, forming a stable support system that combines rigidity and flexibility with prevention.

[0038] Furthermore, S5 monitors the surrounding rock condition in real time through roadway delamination monitoring, surrounding rock surface displacement monitoring, and anchor bolt stress monitoring. Based on the feedback data, it adjusts support parameters to prevent roadway instability, including: Figure 5As shown, roof delamination gauges are installed in the roadway to monitor the stratification displacement between different rock layers in the roof. When the delamination displacement exceeds the threshold, it can provide early warning of potential instability between roof layers, thus providing a basis for decision-making regarding reinforcement grouting or strengthening anchoring. Surface displacement gauges are installed on the sidewalls and floor to detect the overall convergence and floor heave of the roadway cross-section. Especially during the short-term rapid deformation and long-term creep stages, the changes in the convergence rate at different monitoring points can intuitively reveal the evolution of surrounding rock failure. Stress sensors are installed on key load-bearing anchor bolts to monitor the anchor bolt stress state in real time, which can determine the reliability of the anchoring system and avoid secondary damage caused by anchor bolt prestress attenuation or support failure.

[0039] Based on data from roof delamination gauges, surface displacement gauges, and anchor bolt stress sensors, a parametric dynamic control model is proposed to identify roof subsidence and floor heave deformation trends. By adjusting support parameters, the roof subsidence is controlled within the range of 120mm to 200mm, and the floor heave deformation is controlled within 300mm, thus preventing roadway instability. The model includes the following steps: S51 employs a robust Bayesian fusion process based on a gray-box state space to fuse data from roof subsidence gauges, surface displacement gauges, and anchor bolt stress sensors. First, the three types of feedback data undergo unified clock alignment and resampling. Timestamp synchronization and linear interpolation are used to eliminate the influence of different sampling rates, and median filtering is used to remove pulse outliers. Then, the layered displacement data from the roof subsidence gauge, the cross-sectional convergence data from the surface displacement gauge, and the axial force data from the floor heave and anchor bolt stress sensors are mapped to the same roadway cross-sectional reference system through coordinate unification and dimension normalization. A gray-box observation relationship of "surrounding rock-support" is established (a measurement mapping from monitoring points to state quantities such as roof subsidence, floor heave, surrounding rock damage, and equivalent stiffness). Based on this, dual unscented Kalman filtering is used for joint estimation. One filter chain estimates the state variables, while another slowly updates equivalent parameters (such as spray layer and anchoring stiffness, creep-related parameters), using the noise covariance obtained from each sensor calibration as the initial weights. To suppress anomalies and drift, M-estimation (such as Huber) is introduced during the fusion process to adaptively reduce the weights of large residuals, while simultaneously adjusting the noise weights according to innovation statistics. For missing data, filtering prediction steps and RTS smoothing are used to interpolate within a short window to ensure temporal continuity. Soft constraints are applied to the estimation results using "mechanical consistency verification" (such as the closed relationship between anchor bolt axial force and convergence trend), and CUSUM change point detection is triggered when necessary to identify sensor drift and recalibrate the weights. The final output is a smoothed fused state of top plate subsidence, bottom bulge, damage, and equivalent stiffness.

[0040] S52. Dynamic analysis is performed on the monitoring sequences of roof subsidence and floor heave. The time series of roof delamination gauges and surface displacement gauges are converted into displacement rate and acceleration sequences. When the displacement rate is continuously higher than the set safety threshold within 24 to 72 hours after excavation, or when the acceleration shows a positive increasing trend, it indicates that the roadway has entered an accelerated deformation stage and there is a risk of instability. At the same time, the feedback information from the anchor bolt stress sensor is also incorporated into the judgment process. When the anchor bolt tension continuously approaches the yield strength or fluctuates rapidly, and coincides with the accelerated displacement trend of the roof or floor heave, the roadway is judged to have entered a high-risk state.

[0041] S53 After the adverse deformation trend is identified, the rolling prediction method is activated to predict the amount of top plate subsidence and bottom bulge deformation in the next 24 to 72 hours.

[0042] S54 compares the predicted roof subsidence and floor bulge deformation with the set target control range. If the prediction results show that the roof subsidence exceeds the allowable range of 120 to 200 mm or the floor bulge deformation exceeds the safety limit of 300 mm within the next 24 to 72 hours, the optimization module is activated: when the roof subsidence trend approaches the upper limit (monitoring and prediction show that it will approach or exceed 200 mm within the next 2–7 days), the overall constraint stiffness is improved by increasing the preload of anchor bolts or anchor cables. The preload adjustment adopts the engineering rule of "small steps and quick adjustments, and graded stop-loss". For commonly used resin anchor rods (20-22mm level, single ultimate pull-out force of about 200-240kN), the preload is first increased by 10-20kN each time based on the original design preload, and the cumulative increase shall not exceed 60%-70% of the design value or the safety limit of 140-160kN. For 15.2mm single-strand steel strand anchor cables, the preload is first increased by 20-30kN each time based on the original preload level, and the cumulative increase shall not exceed 180-200 kN or 70% of the limit. If the preload is close to the design limit, the sealing bearing capacity can be improved by thickening the shotcrete layer. This involves first adding a 20-30mm wet-sprayed layer of steel fiber (C30 / 35 grade, steel fiber approximately 30-40kg / m³) to key areas such as the arch crown and corners. The interface must be roughened, cleaned, and treated with an interface agent to improve adhesion. After curing for 24-72 hours and retesting the settlement rate and cracks, a second 20-30mm layer can be added (cumulative +40-60mm), increasing the total thickness from the original design to the range of 100-120mm. However, due to clearance and design limits, further thickening is not advisable. The thickness of a single additional layer should not exceed 30-40mm to avoid shrinkage. Cracking and hollowing should be controlled with a rebound rate of ≤15%, and the pull-out / adhesion force ≥1.0MPa should be used as the criterion for bonding quality. Thickening can usually significantly improve the equivalent stiffness and crack resistance of the sealing layer (the bending stiffness of the plate and shell is sensitive to the thickness). In engineering, this is manifested by a significant drop in the top arch displacement rate within 24–72h, a reduction in the peak axial force of the anchor bolts, and a convergence of fluctuations, thereby achieving stronger sealing and constraint of the surrounding rock. If the retest shows that the top plate displacement rate has not decreased enough (e.g., <30%), then it is no longer necessary to simply continue to thicken the layer. Instead, the grouting pressure should be increased / the grouting holes should be densified or the pressure should be locally relieved to avoid excessive thickening causing interface slippage and an increase in the additional load of self-weight, which is detrimental to the support.When the heave development intensifies, the grouting section length is shortened to enhance the constraint and load-bearing capacity of the base plate. In this embodiment, based on the initial design length of 1.5–2.0m for base plate reinforcement, the first-level optimization first reduces it to 1.2–1.4m (approximately -20%), while maintaining the original design grouting pressure of 6–8MPa but extending the pressure holding time by 8–12 minutes. If the heave rate decreases by less than 30% within 24–72 hours, the second-level optimization further reduces the section length to 0.8–1.0m (approximately -40%), while simultaneously increasing the grouting capacity of the single hole. The upper limit of the discharge volume is increased by 20-30%, the spacing of the grout stoppers in the borehole section is increased to 0.8-1.0m, and the "low discharge volume - segmented - secondary backfilling" process is adopted to ensure dense bonding; if the standard is still not met and no leakage or uplift abnormality occurs, the short-segment grouting of 0.6-0.8m (about -60%) is optimized to the extreme, but the pressure must be strictly limited (the top pressure does not exceed the upper limit of the surrounding rock, and the pressure is maintained in small steps within the upper limit of 6-8MPa), the discharge volume is limited, and the pressure holding time is extended by 12-20min to prevent water splitting and local uplift. If monitoring results show that the surrounding rock is active and the grouting consolidation effect is insufficient, the grouting pressure is increased to expand the grout diffusion radius and cementation range, thereby improving the overall integrity of the surrounding rock. In this embodiment, based on the original design pressure of 6-8 MPa, the pressure is first increased by 0.5-1.0 MPa to 7.0-8.5 MPa and held for 8-12 minutes to observe the grout absorption and pressure-time curves. If no abnormalities occur (such as a sudden increase in grout return at the borehole, sudden pressure linkage between adjacent boreholes, bottom plate lifting >1-2 mm, or a sudden pressure drop indicating hydraulic fracturing), the pressure is further increased to 8.5-9.5 MPa. If necessary, the pressure may be briefly reached at the upper limit of 10 MPa, but it must not exceed the "allowable top pressure of the surrounding rock" (determined by combining water pressure / trial grouting test and packer rating) and the design limit. Throughout the process, small discharge, segmented packing, extended pressure holding (such as holding pressure for 12-20 minutes longer per segment) and "secondary backfilling" are used to increase the grouting energy and residence time per unit length. In areas where localized roof cracks widen by 1 mm or more within 48-72 hours, a denser anchor bolt arrangement is adopted. Specifically, in the crown arch and arch corner areas, based on the actual direction of the cracks, the crack boundaries are extended outward by approximately 1.0-1.5 m, and the areas requiring key reinforcement, i.e., the "reinforcement zone," are marked on the surrounding rock surface with spray paint. The original 0.9 m × 0.9 m anchor bolt arrangement is denser than the previous 0.6–0.75 m × 0.6–0.75 m quincunx grid, ensuring that the newly added anchor holes cross the cracks and are aligned with the crack reinforcement method. To form a "cross-joint suture" by forming an angle of 45–90°; for through or bifurcated cracks, add a short anchor (2.4–2.7m) and a diagonal anchor (20–30° to the horizontal) every 0.6–0.8m along the joint; and add a 5.5–6.0m anchor cable every 1.8m along the centerline of the top arch as a deep "locking arch". The newly added anchor rods are anchored for their full length; then, a 20–30mm steel fiber spray layer is applied to the densified area, followed by interface roughening, cleaning, and interface agent treatment, and pressure curing for 24–72 hours.After the densification is completed, the crack width, delamination, convergence, and anchor stress are re-measured 24–72 hours later. If the crack widening stops and the top arch displacement rate decreases by more than 30% and remains stable for three days, the arrangement is maintained. If the crack continues to develop, a new row of densification is moved 0.6–1.0m outward from the crack tip and linked with short-section grouting until local stability is achieved.

[0043] This invention employs a multi-element collaborative design involving "steel wire rope reinforcement + shotcrete sealing layer + hollow grouting anchor bolts + pressure relief grooves + dynamic monitoring and control." On one hand, the steel wire rope and shotcrete layer construct an integral closed structure, enhancing the tensile and impact resistance of the surrounding rock and mitigating uneven deformation and crack propagation. On the other hand, the combined anchoring and grouting support organically integrates anchoring and grouting, constructing a composite structure similar to reinforced concrete, significantly improving the bearing capacity and long-term stability of the surrounding rock. Simultaneously, pressure relief grooves are placed in stress concentration areas to actively release local stress and prevent sudden instability. Finally, multi-dimensional monitoring and feedback of roof delamination, surface displacement, and anchor bolt stress, combined with robust Bayesian fusion and dynamic prediction models, enables rolling optimization and real-time control of support parameters. This method not only effectively controls asymmetric deformations such as roof subsidence, floor bulging, and sidewall convergence but also considers both short-term strength and long-term creep control, significantly improving the overall stability and service life of the roadway. Compared to existing technologies, it is more adaptable and reliable under complex conditions of deep soft rock.

[0044] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0045] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A support method for deep wells with high stress and steep inclination in soft rock tunnels, characterized in that, Includes the following steps: S1 analyzes the physical and mechanical parameters, geostress distribution, and hydrological conditions of the surrounding rock of the tunnel to identify the creep characteristics and asymmetric deformation mechanism of soft rock. S2 uses steel wire rope as reinforcement, combined with shotcrete to form a sealing layer; S3 combines anchoring and grouting through a new type of hollow grouting anchor. S4, stress relief grooves are arranged in the stress concentration area to reduce the local stress concentration effect of the surrounding rock and achieve stress regulation together with anchor injection; S5 monitors the surrounding rock condition in real time through roadway delamination monitoring, surrounding rock surface displacement monitoring, and anchor bolt stress monitoring, and adjusts support parameters based on feedback data to prevent roadway instability. In step S5, based on data from the roof delamination gauge, surface displacement gauge, and anchor bolt stress sensor, a parametric dynamic control model is proposed to identify the trends of roof subsidence and floor heave in the roadway. This model includes the following steps: S51 performs time-series alignment, anomaly suppression, and feature mapping on sensor data; S52, Identify the deformation stage of the tunnel; S53, predict the amount of roof subsidence and floor heave deformation in the roadway; S54. The predicted subsidence of the top plate and the deformation of the bottom heave are compared with the set target control range. If the prediction exceeds the limit, measures are taken in sequence to increase the pre-tightening force of the anchor bolts, thicken the shotcrete layer, shorten the grouting section length, increase the grouting pressure, and densify the anchor bolt arrangement. The densified anchor bolt arrangement is used in conjunction with the steel fiber spray layer to focus on reinforcing the crack area. After the reinforcement is completed, the cracks and the displacement of the top arch are continuously monitored. If they still develop, short-segment grouting is carried out to reduce the deformation rate of the top plate and the bottom heave.

2. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that... The analysis described in S1 targets roadways with a burial depth exceeding 1000 meters and a coal seam dip angle of 23°-36°. The surrounding rock includes roof mudstone, siltstone, and floor fine sandstone. The roadway cross-section is a straight-walled semi-circular arch with a net width of 5.0 meters and a net height of 4.0 meters. The analysis identifies the failure characteristics of the surrounding rock as "rapid initial deformation + long-term creep + asymmetric displacement".

3. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that... The sealing layer described in S2 is a "inner steel wire rope mesh + outer shotcrete" structure: the steel wire rope mesh spacing is 200-300 mm, the shotcrete is applied in multiple layers, each layer is 5-8 cm thick, the total thickness is not less than 80 mm, the concrete is mixed with early strength agent, water reducing agent and crack-resistant fiber, and wet spraying process is adopted.

4. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, In S54, for areas where local roof cracks widen by 1 mm or more within 48-72 hours, a denser anchor bolt arrangement is used. In the arch and arch corner areas, the crack boundary is extended outward by approximately 1.0-1.5 m according to the actual direction of the crack. The area requiring key reinforcement, i.e., the "reinforcement zone," is marked on the surrounding rock surface with spray paint. The original 0.9m×0.9m anchor bolt arrangement is densified into a 0.6–0.75m×0.6–0.75m quincunx grid, forming a 45–90° angle with the crack normal to create a "cross-crack stitch." For continuous or bifurcated cracks, a short anchor and a... For inclined anchors, a 5.5–6.0m anchor cable is added every 1.8m along the centerline of the top arch as a deep "arch lock". The newly added anchors are anchored along their full length. Then, a 20–30mm steel fiber spray layer is applied to the densified area, followed by interface roughening, cleaning, and interface agent treatment, and pressure curing for 24–72 hours. After densification, the crack width, delamination, convergence, and anchor stress are re-measured after 24–72 hours. If crack widening stops and the top arch displacement rate decreases by more than 30% and remains stable for three days, this arrangement is maintained. If further development occurs, a new row of densified anchors is moved 0.6–1.0m outward from the crack tip and linked with short-section grouting until local stability is achieved.

5. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, The new type of hollow grouting anchor described in S3 has a length of not less than 2.5 meters, a spacing of 0.9 meters, and a pull-out force of not less than 228 kN; the matching anchor cable has a length of not less than 5.5 meters and a spacing of 1.8 meters; the grouting pressure is 6-8 MPa, and the grout diffusion radius is not less than 1.5 meters, so as to achieve the combined effect of "anchor constraint + grout reinforcement".

6. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, The grouting process described in S3 is divided into a compaction stage, a splitting stage, and a passive inhibition stage, which improves the cohesion and friction angle of the surrounding rock and forms a "surrounding rock-anchor bolt-grout" composite.

7. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, The stress relief grooves described in S4 are arranged in the stress concentration areas of the tunnel roof arch corners and the lower sidewalls of the floor. They release stress through localized minor deformation of the rock mass and work in conjunction with sealing and anchoring to achieve stress regulation.

8. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, The monitoring described in S5 includes: installing delamination gauges on the top plate to monitor delamination displacement, installing surface displacement gauges on the two sides and bottom plate to monitor cross-sectional convergence and bottom bulging, and installing stress sensors on key anchor bolts to monitor axial force.

9. The support method for deep well high-stress and steeply inclined soft rock tunnels according to claim 1, characterized in that, The new hollow grouting anchor described in S3 uses a combination of end anchoring and full-length bonding to ensure that the axial constraint force is uniformly applied to the surrounding rock.

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