Active and passive integrated supporting method and system for soft rock roadway based on dynamic stiffness regulation

Abstract

A kind of soft rock roadway active and passive integrated support method and system based on dynamic stiffness regulation belongs to intelligent support technical field, method: after tunneling, high-strength anchor rod / anchor cable is formed pressure stress zone according to design pre-tightening force, and flexible protective surface is formed by spraying fiber concrete;When deformation rate meets criterion, install constant resistance pressure relief device to actively reduce stiffness, while grouting and reinforcing broken zone;After deformation rate continues to decline, erect collapsible U-shaped steel support and wall backfilling, and form collaborative bearing ring with anchoring-grouting reinforcement ring;After evaluating that safety factor meets requirements, overall cast reinforced concrete lining;System: data perception module includes laser converging instrument, multipoint displacement meter, pressure sensor and strain gauge;Analysis decision module includes stage identification unit, key parameter calculation unit and decision instruction output unit;Support execution subsystem includes first, second, third and fourth stage execution components.The present application can significantly improve the quality controllability and reliability of support engineering.

Description

Technical Field

[0001] This invention belongs to the field of intelligent support technology, specifically a method and system for integrated active and passive support of soft rock roadways based on dynamic stiffness control. Background Technology

[0002] As mineral resource mining in my country continues to advance deeper, the geological environment faced by underground engineering projects is becoming increasingly complex. Among these challenges, the stability control of soft rock tunnels has become a key technical bottleneck restricting safe and efficient production. Soft rock generally refers to rock masses with low strength, poor cementation, easy weathering, and significant rheological properties. After tunnel excavation, under the combined effects of high ground stress and engineering disturbance, the surrounding rock undergoes large-scale and continuous plastic deformation and fracturing. Relying solely on a single active support method (such as bolt support) is often insufficient to effectively curb this deformation trend. Both engineering practice and theoretical research indicate that for such tunnels, a support concept combining strong active and strong passive support must be adopted. Strong active support applies high preload to constrain the shallow surrounding rock in a timely manner, forming an active load-bearing structure; strong passive support provides the final rigid load-bearing and containment space for large deformations in the deeper parts of the surrounding rock. The two complement each other and are indispensable. Without strong passive support, the support system is prone to gradual failure under long-term rheological pressure. Conversely, if the strong passive structure is introduced too late or becomes disconnected from the active support, it will be difficult to fully realize its load-bearing potential, increasing costs and resulting in unsatisfactory support effects. Therefore, achieving scientific synergy between active and passive support in time and space, and constructing an integrated load-bearing system, is the fundamental way to solve the support problems of soft rock tunnels.

[0003] Currently, the academic and engineering communities have conducted a series of explorations regarding the coordinated active and passive support of soft rock tunnels. Existing research mainly focuses on two aspects: first, developing high-performance active support components such as high-prestressed anchor bolts (cables) and constant-resistance pressure-relief devices; second, optimizing the form and strength of passive structures such as U-shaped steel supports and concrete linings. However, these studies and practices still have significant systemic defects. First, at the conceptual level, most studies still regard active and passive support as two relatively independent subsystems, and their design and construction are often carried out step by step. There is a lack of a unified mechanical model and integrated design method based on the entire deformation process of the surrounding rock, which leads to the inability to fully realize the synergistic effect of the support structure. For example, existing technologies usually design and construct active support such as anchor bolts and passive support such as U-shaped steel supports and concrete linings as independent stages. The two lack a synergistic mechanism based on the real-time deformation state of the surrounding rock, resulting in either excessive rigidity of the support in the early stage, leading to premature damage, or ineffective control of the surrounding rock rheology due to the lag in the intervention of passive support. Secondly, regarding timing, the intervention of passive support largely relies on experience-based judgment, typically only after active support has clearly failed. This fails to precisely match the critical stage of surrounding rock deformation energy release, thus missing the optimal opportunity to control deformation. Finally, in terms of control methods, existing methods are mostly static or pre-set. They cannot adjust the overall stiffness and bearing capacity of the support system in stages and adaptively based on the dynamic changes in the surrounding rock's real-time response after tunnel excavation. Furthermore, the determination of support parameters largely depends on static theoretical calculations and engineering experience, making dynamic optimization based on the key processes of surrounding rock stress adjustment, plastic zone development, and energy release. Ultimately, the support system either fails early due to excessive rigidity or becomes uncontrollably flexible. These shortcomings make it difficult for existing technologies to economically and reliably cope with complex and variable deep soft rock tunnel conditions.

[0004] Therefore, there is an urgent need for an integrated support method and system that can actively adjust the overall stiffness of the support system based on real-time feedback of surrounding rock deformation, and achieve close temporal and mechanical coupling between active and passive structures, so as to scientifically coordinate the relationship between support strength, deformation control and economic benefits. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method and system for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation. This method enables the overall stiffness of the support system to evolve in a stepwise manner according to the actual development process of surrounding rock deformation, significantly improving the quality controllability and reliability of the support project. Simultaneously, it offers excellent economic benefits and adaptability to complex surrounding rock conditions. The system can dynamically adjust the support stiffness and strategy according to the surrounding rock deformation, scientifically coordinating the contradiction between deformation control and stress release, improving adaptability to complex soft rock conditions. Furthermore, quantitative safety calculations ensure safety reserves at each stage, effectively reducing the risk of support failure and significantly improving the adaptability and reliability of the support.

[0006] To achieve the above objectives, this invention provides a method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation, comprising the following steps:

[0007] S1: Determination of key parameters and initial active support design;

[0008] Key parameters were determined through exploration and testing. The initial preload of the anchor was determined based on the yield strength of the rod and the stress reduction value of the overlying rock layer. The critical deformation rate threshold was determined based on the strength modulus ratio of the surrounding rock and the ratio of the equivalent radius to the effective length of the anchor.

[0009] S2: Phase One - Immediate Active Constraints and Flexible Surface Protection;

[0010] After the tunnel is excavated, high-strength anchor bolts / cables are immediately installed according to the design pre-tightening force to form a compressive stress zone on the surface of the surrounding rock; then fiber concrete is sprayed to form a protective layer with set flexibility and crack resistance, realizing immediate sealing and preliminary joint support of the surrounding rock surface, and finally constructing an initial high-rigidity support system.

[0011] S3: Second stage—coupled controllable pressure relief and surrounding rock modification;

[0012] When the roadway deformation rate meets the set criteria, a constant resistance pressure relief device is installed and the stiffness of the support system is actively reduced to achieve controllable pressure relief and energy release of the surrounding rock. At the same time, the surrounding rock in the fractured plastic zone is reinforced by grouting to enhance the self-supporting capacity of the surrounding rock.

[0013] S4: Third Stage—Rigid Structure Coordination and Load-Bearing Circle Closure;

[0014] After the deformation rate continues to decrease, a collapsible U-shaped steel support is erected and backfilling is carried out to make it closely integrated with the anchor-grouting reinforcement ring formed in the early stage, forming a synergistic bearing ring in which multiple components share the force, and realizing a second leap in system stiffness.

[0015] S5: Phase Four—Overall Stability and Permanent Closure;

[0016] After the stability assessment confirmed that the safety factor of the collaborative bearing ring met the requirements, the reinforced concrete lining was poured as a whole to form an integrated permanent support structure, so that the system stiffness reached the design maximum value.

[0017] Furthermore, in order to provide a scientific basis and quantitative criteria for phase transitions in active support design, and to achieve precise control from experience-based decision-making to data-driven approaches, the process of determining key parameters and initial active support design in S1 is as follows:

[0018] S11: Determination of surrounding rock conditions and key parameters; determination of tunnel depth through geological exploration and laboratory tests. Average unit weight of overlying strata Uniaxial compressive strength of surrounding rock Deformation modulus of surrounding rock Rock mass integrity index, equivalent radius of tunnel ;

[0019] S12: Design of initial preload of anchor bolt; calculate the initial preload of anchor bolt according to formula (1). ;

[0020] (1);

[0021] In the formula, The yield strength of the anchor rod material; The cross-sectional area of ​​the anchor rod; and These refer to the anchor bolt spacing and row spacing, respectively. The stress adjustment coefficient is used to reflect the rock mass integrity and construction disturbance.

[0022] S13: Determination of the critical deformation rate threshold; estimate the critical deformation rate threshold according to formula (2). ;

[0023] (2);

[0024] In the formula, This is an empirical coefficient that combines engineering analogies and theoretical analysis. This is the effective length of the anchor bolt. The unit speed.

[0025] Furthermore, in order to effectively suppress early deformation of the surrounding rock, the first stage in S2—the process of immediate active restraint and flexible surface protection—is as follows:

[0026] S21: Construction of high-prestressed anchor bolts / cables; After the tunnel excavation is completed, during the critical window period before the original strength of the surrounding rock has significantly deteriorated, high-strength resin anchoring agents and ultra-high-strength prestressed anchor bolts / cables are used, according to the prestressing force... When combined with hydraulic tensioning equipment to apply high pre-tension force, strong active support is formed, and a compressive stress zone is quickly constructed on the surface of the surrounding rock.

[0027] S22: Flexible protective spraying; On the grid base of the anchor support, C20 / C25 concrete mixed with polypropylene fiber or steel fiber is sprayed to form a protective layer with set flexibility and crack resistance, completing the immediate sealing and preliminary joint support of the surrounding rock surface.

[0028] S23: First-stage system stiffness established; after the completion of the first stage, the support system achieves initial high stiffness. ;

[0029] Furthermore, in order to achieve the synergistic effect of yielding to pressure with flexibility and modifying the surrounding rock with rigidity, and to effectively coordinate the contradiction between deformation control and stress release, the second stage in S3—the coupling process of controllable yielding to pressure and surrounding rock modification—is as follows:

[0030] S31: Stage start-up criterion determination; Based on continuous monitoring data of roadway convergence deformation, when the surrounding rock deformation development enters the critical stage of continuous expansion of the plastic zone but has not yet become unstable, determine whether formula (3) and formula (4) are satisfied at the same time; If the determination condition is met, execute S32; otherwise, continue monitoring and take reinforcement measures until the determination condition is met.

[0031] (3);

[0032] (4);

[0033] In the formula, The surface convergence velocity of the tunnel;

[0034] S32: Pressure relief device installation; A constant resistance, large deformation pressure relief device with specific constant resistance characteristics is installed between the anchor bolt / anchor cable tray and the solidified sprayed layer. The constant resistance value of the constant resistance, large deformation pressure relief device is specified. Set according to formula (5);

[0035] (5);

[0036] In the formula, To allow for pressure control coefficient;

[0037] S33: Grouting reinforcement; Through the pre-set hollow channel of the anchor bolt or a separately arranged special grouting pipe, single-liquid cement grout or cement-water glass double-liquid grout with adjustable gel time is used to perform pressure-controlled grouting reinforcement of the surrounding rock in the fractured or plastic zone outside the anchor bolt anchoring section.

[0038] S34: Second-stage system stiffness adjustment; after pressure relief initiation, the system stiffness is actively adjusted to a lower level. .

[0039] Furthermore, in order to significantly improve the integrity and deformation resistance of the support system, in S4, the third stage - the process of rigid structure coordination and bearing circle closure is as follows:

[0040] S41: Judgment of stage start conditions; After the yielding and grouting measures in the second stage take effect and the surrounding rock deformation rate shows a significant and continuous downward trend and reaches the predetermined threshold, this stage is started.

[0041] S42: Erection of yieldable U-shaped steel support; Manually erect a standard specification yieldable U-shaped steel support close to the roadway wall, and its connecting clip is reserved with a specific yieldable amount according to the design. ; Among them, the yieldable amount is determined according to formula (6). ;

[0042] (6);

[0043] In the formula, is the safety reserve coefficient considering uncertain factors such as long-term rheology, etc.; is the net deformation amount of the surrounding rock orderly released through the yielding device in the second stage obtained based on the monitoring data;

[0044] S43: Backfill behind the wall; After the support is erected, immediately fill the gap between the support and the roadway wall with C30 fine aggregate concrete or high-strength precast concrete blocks to ensure that the support is tightly combined with the previously formed anchoring - grouting reinforcement circle without voids, forming a collaborative bearing circle in which multiple components jointly bear the load.

[0045] S44: System stiffness jump in the third stage; After the rigid support system is added, the system stiffness jumps to .

[0046] Furthermore, in order to ensure durable support, in S5, the fourth stage - the process of overall stability and permanent closure is as follows:

[0047] S51: Quantitative evaluation of overall stability; After the collaborative bearing circle formed in the third stage undergoes observation for a period of stable period, its overall stability is quantitatively evaluated; In the process of quantitative evaluation, the overall safety factor is calculated according to formula (7). , if , the evaluation is qualified, otherwise reinforcement measures are taken until the re-evaluation is qualified; Among them, is the allowable safety factor specified by the design code;

[0048] (7);

[0049] In the formula, , , The bearing capacity of the anchor system, grouting reinforcement ring, and U-shaped steel support is estimated based on material strength and geometric parameters, respectively. The surrounding rock load is estimated based on the theory of in-situ stress and plastic zone range;

[0050] S52: Reinforced concrete lining pouring; After passing the assessment, reinforced concrete lining is poured as a whole in the innermost layer. This lining serves as the final safety reserve and durability guarantee, and is firmly combined with the internal cooperating bearing ring to form an integrated permanent support structure with high rigidity and strong integrity.

[0051] S53: The final stiffness of the fourth stage is determined; after the fourth stage is completed, the system stiffness reaches the design maximum value. .

[0052] This invention addresses the technical challenges of long-term temporal and mechanical disconnect between active and passive support in controlling large deformations in soft rock tunnels, and the mismatch between system stiffness and the dynamic deformation process of the surrounding rock. It provides an integrated active-passive collaborative support method based on the perception of the surrounding rock's dynamic response. By integrating existing mature support technologies such as high-preload anchor bolts, constant-resistance pressure-relief devices, grouting reinforcement, retractable U-shaped steel supports, and concrete lining, an integrated collaborative bearing system is constructed that actively adjusts stiffness in stages based on real-time deformation feedback from the surrounding rock.

[0053] First, key parameters such as tunnel depth, surrounding rock strength, and deformation modulus are determined through geological exploration and laboratory tests, providing a scientific basis for support design. The initial preload of the anchor bolts is quantitatively determined based on the yield strength of the bolt body and the stress reduction value of the overlying strata, avoiding uncertainties caused by empirical values. The critical deformation rate threshold is determined based on the ratio of surrounding rock strength modulus and the ratio of equivalent radius to effective anchor bolt length, providing clear quantitative criteria for subsequent stage transitions and shifting support decisions from "experience-dependent" to "data-driven."

[0054] Secondly, high-strength anchor bolts / cables are immediately installed and high preload is applied after tunnel excavation to quickly form a compressive stress zone on the surface of the surrounding rock, actively inhibiting early deformation and deterioration. Fiber-reinforced concrete is then sprayed to form a flexible protective layer, which serves to seal the surrounding rock, resist cracking, and cooperate with the anchor bolts in bearing load, achieving "immediate sealing + preliminary combined support." After the first stage is completed, an initial high-rigidity support system is constructed. This lays the foundation for subsequent pressure and reinforcement.

[0055] Subsequently, when the deformation rate meets the set criteria, a constant resistance relief device is installed to actively reduce the stiffness of the support system. This process achieves controllable pressure relief and orderly energy release in the surrounding rock, preventing sudden instability. Simultaneously, grouting reinforces the fractured plastic zone of the surrounding rock, enhancing its self-supporting capacity and creating a dual effect of "relieving pressure with flexibility and modifying its properties with rigidity." This stage achieves synergy between "active weakening" and "surrounding rock strengthening," reconciling the contradiction between controlling deformation and releasing stress.

[0056] Furthermore, after the deformation rate continues to decrease, a collapsible U-shaped steel support is erected and backfilling is carried out to ensure a tight bond between the support and the previously formed anchor-grouting reinforcement ring. This creates a synergistic load-bearing ring where multiple components (anchor bolts, grouting body, and support) share the load, achieving a secondary increase in system stiffness. The compressibility design allows for slight deformation space, avoiding stress concentration and improving the structure's adaptability.

[0057] Finally, after a stability assessment (such as safety factor calculation) confirms that the co-bearing ring meets the requirements, the reinforced concrete lining is poured as a whole to form an integrated permanent support structure with maximum stiffness and strongest integrity. As a final safety reserve and durability guarantee, it ensures the long-term stability of the support system.

[0058] This method establishes dynamic decision criteria based on monitoring indicators such as deformation rate, enabling the overall stiffness of the support system to evolve in a stepwise manner according to the actual development process of surrounding rock deformation. , , , The entire process follows a proactive control logic of actively weakening to release energy and gradually strengthening to build stability. It scientifically coordinates the contradiction between controlling deformation and releasing stress, significantly improving the support system's adaptability to complex surrounding rock conditions. Simultaneously, through quantitative safety calculations and stage transition condition control, it avoids blind and over-strengthening of the support, optimizing material usage while ensuring long-term roadway stability, reducing rework due to support failure, and resulting in significant economic benefits. Based on mature support components and construction techniques, this method provides a standardized and highly operable support operation procedure for soft rock roadways through systematic process integration and quantitative decision support. It reduces over-reliance on individual experience and improves the quality controllability and reliability of support engineering.

[0059] The present invention also provides an integrated active and passive support system for soft rock roadways based on dynamic stiffness control, which is used to realize an integrated active and passive support method for soft rock roadways based on dynamic stiffness control, including a data sensing module, an analysis and decision-making module, and a support execution subsystem;

[0060] The data sensing module includes a laser convergence unit, a multi-point displacement meter, a pressure sensor, and a strain gauge, used to collect multi-source monitoring data;

[0061] The analysis and decision-making module includes a stage identification unit, a key parameter calculation unit, and a decision command output unit. The stage identification unit determines the current support stage based on the deformation rate and trend provided by the data sensing module and outputs a stage start / conversion command. The key parameter calculation unit calculates key design parameters in real-time or initially based on geological survey, indoor test, and field monitoring data. Key design parameters include the initial preload of the anchor bolts, the critical deformation rate threshold, the constant resistance value of the constant resistance relief device, the allowable shrinkage of the U-shaped steel support, and the overall safety factor. The decision command output unit receives the determination results from the stage identification unit and the design values ​​from the key parameter calculation unit, and outputs specific operation commands to each component of the support execution subsystem. In the first stage, it outputs the anchor bolt preload application value, shotcrete mix ratio, and thickness. In the second stage, it outputs the installation timing and constant resistance value of the relief device, grouting pressure, and grout type. In the third stage, it outputs the U-shaped steel support erection timing, shrinkage setting value, and backfill material. In the fourth stage, it outputs the reinforced concrete lining pouring command and safety factor confirmation.

[0062] The support execution subsystem includes a first-stage execution component, a second-stage execution component, a third-stage execution component, and a fourth-stage execution component. The first-stage execution component is used to achieve rapid active support and surface sealing after tunnel excavation, forming an initial high-rigidity system. The second-stage execution component is used to actively reduce the system stiffness to achieve controllable pressure relief, while simultaneously reinforcing the plastic zone of the surrounding rock with pressure grouting to improve the self-supporting capacity of the surrounding rock. The third-stage execution component is used to erect rigid supports and tightly integrate them with the previous anchoring-grouting reinforcement ring to form a synergistic bearing ring, achieving a second leap in system stiffness. The fourth-stage execution component is used to integrally cast reinforced concrete lining in the innermost layer, forming an integrated permanent support structure with the greatest stiffness and strongest integrity, serving as the final safety reserve and durability guarantee.

[0063] Furthermore, in order to comprehensively and in real-time collect multi-source data such as surrounding rock deformation and support structure stress, and to provide a precise monitoring basis for dynamic stiffness control, the laser convergence instrument is deployed on the roadway surface to collect the roadway surface convergence displacement and convergence velocity. The multi-point displacement gauges are deployed in the deep area of ​​the surrounding rock to collect displacement data at different depths within the rock. The pressure sensors are deployed on the anchor bolt tray and U-shaped steel support to collect the bearing capacity of the anchor bolt / anchor cable. The load-bearing capacity of the U-shaped steel support; the strain gauges are installed on the anchor tray and the U-shaped steel support to collect the strain and deformation of the support components.

[0064] Furthermore, in order to achieve objective quantification and precise control of the initiation and switching of the support phase, avoid subjective misjudgment, and ensure that intervention measures at each stage are executed at the most favorable time, the process by which the phase identification unit determines the current support phase and outputs the phase initiation / switching command is as follows: When simultaneously satisfying the following conditions... and When the deformation rate shows a significant and continuous decreasing trend and reaches a predetermined threshold, the second stage is initiated; when the deformation rate reaches a predetermined threshold, the third stage is initiated; after stability assessment, the overall safety factor is determined. At that time, the fourth stage is initiated.

[0065] Furthermore, in order to achieve standardized and modular configuration of the support process, facilitate rapid on-site construction, and ensure the reliable execution of technical measures at each stage, the first stage execution components include anchor bolts / anchor cables, high-strength resin anchoring agent, anchor bolt drilling rig, hydraulic tensioning equipment, and fiber concrete spraying equipment;

[0066] The second-stage execution components include a constant-resistance large-deformation pressure relief device, a grouting subsystem, and grouting materials;

[0067] The third-stage execution components include a retractable U-shaped steel support, backfill material, and filling construction equipment;

[0068] The fourth stage execution components include reinforcing steel, concrete, formwork and vibrating equipment, and pouring and curing devices.

[0069] This invention creates an "integrated active and passive support method for soft rock roadways based on dynamic stiffness regulation." This method treats the entire support process as a controllable dynamic system. By clearly defining stage divisions and transition criteria, it closely links high-preload active support, constant-resistance pressure-yielding deformation, surrounding rock grouting modification, compressible rigid supports, and final lining in terms of time sequence and mechanical logic. Its innovation lies in enabling the support system to actively and systematically adjust its overall stiffness based on real-time feedback from surrounding rock deformation, undergoing an evolutionary process of "immediate strengthening—controllable pressure yielding—synergistic enhancement—final stabilization." This achieves adaptive control of roadway deformation and integrated construction of the load-bearing structure, ultimately reaching an optimal balance between safety and economy.

[0070] In this invention, a data sensing module (laser convergence instrument, multi-point displacement gauge, pressure sensor, strain gauge) facilitates real-time acquisition of multi-source monitoring data, providing accurate and continuous surrounding rock condition information for the analysis and decision-making module. This frees support decisions from reliance on experience and provides a scientific data foundation. The analysis and decision-making module incorporates a stage identification unit, which automatically determines the current support stage based on deformation rate and trend, and outputs stage initiation / transition commands. This upgrades from manual judgment to intelligent identification, ensuring accurate and timely stage transitions. Based on key parameter calculation data, the module can calculate core design parameters such as anchor bolt preload, critical deformation rate threshold, constant resistance, allowable retraction, and safety factor in real-time or initially, using geological survey, laboratory test, and field monitoring data. This allows the support design to dynamically adjust with changes in surrounding rock conditions, avoiding the problems of fixed parameters and poor adaptability in traditional methods. The decision command output unit outputs specific operation commands (such as pre-tightening force value, spraying ratio, pressure relief timing, grouting pressure, support shrinkage, pouring command, etc.) for the four support stages. It can automatically and efficiently convert the analysis results directly into executable construction parameters, providing a scientific reference for subsequent construction.

[0071] The support execution subsystem is divided into four independent components, each corresponding to mature technologies such as high pre-tightening anchor bolts and flexible spraying, constant resistance pressure relief and grouting, U-shaped steel supports and backfilling, and reinforced concrete lining. The timing between each component is clear and the connection is close, realizing the synergistic integration of active and passive support in terms of time and mechanics.

[0072] This system can dynamically adjust the support stiffness and strategy according to the deformation of the surrounding rock. , , , This approach scientifically coordinates the contradiction between deformation control and stress release, improving adaptability to complex soft rock conditions. Simultaneously, quantitative safety calculations ensure safety reserves at each stage, effectively reducing the risk of support failure and significantly enhancing its adaptability and reliability. Furthermore, precise stage-based initiation control and parameter optimization avoid over-support or ineffective repairs, reducing material waste and construction delays, achieving good technical and economic results, and optimizing costs and schedules. Moreover, breaking down the complex soft rock support process into standardized, quantifiable modules and procedures reduces reliance on individual experience, facilitating application in similar projects, improving the quality control of support engineering, promoting standardized operations, and enabling widespread adoption. Attached Figure Description

[0073] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0074] The invention will now be further described with reference to the accompanying drawings.

[0075] like Figure 1 As shown, this invention provides an integrated active and passive support method for soft rock roadways based on dynamic stiffness regulation, comprising the following steps:

[0076] S1: Determination of key parameters and initial active support design;

[0077] Key parameters were determined through exploration and testing. The initial preload of the anchor was determined based on the yield strength of the rod and the stress reduction value of the overlying rock layer. The critical deformation rate threshold was determined based on the strength modulus ratio of the surrounding rock and the ratio of the equivalent radius to the effective length of the anchor. This provides a quantitative basis for the active support and stage transition in subsequent stages.

[0078] S2: Phase One - Immediate Active Constraints and Flexible Surface Protection;

[0079] After the tunnel is excavated, high-strength anchor bolts / cables are immediately installed according to the design pre-tightening force to form a compressive stress zone on the surface of the surrounding rock. Then, fiber-reinforced concrete is sprayed to form a protective layer with set flexibility and crack resistance, realizing immediate sealing and preliminary joint support of the surrounding rock surface. Finally, an initial high-rigidity support system is constructed to suppress early deformation and deterioration of the surrounding rock.

[0080] S3: Second stage—coupled controllable pressure relief and surrounding rock modification;

[0081] When the roadway deformation rate meets the set criteria, a constant resistance pressure relief device is installed and the stiffness of the support system is actively reduced to achieve controllable pressure relief and energy release of the surrounding rock. At the same time, the surrounding rock in the fractured plastic zone is reinforced by grouting to enhance the self-supporting capacity of the surrounding rock and achieve the dual effect of "pressure relief with softness and modification with rigidity".

[0082] S4: Third Stage—Rigid Structure Coordination and Load-Bearing Circle Closure;

[0083] After the deformation rate continues to decrease, a collapsible U-shaped steel support is erected and backfilling is carried out to make it closely integrated with the anchor-grouting reinforcement ring formed in the early stage, forming a synergistic bearing ring in which multiple components share the force, and realizing a second leap in system stiffness.

[0084] S5: Phase Four—Overall Stability and Permanent Closure;

[0085] After the stability assessment confirms that the safety factor of the co-bearing ring meets the requirements, the reinforced concrete lining is poured as a whole to form an integrated permanent support structure with the greatest stiffness and the strongest integrity, so that the system stiffness reaches the design maximum value, serving as the final safety reserve and durability guarantee.

[0086] To provide a scientific basis and quantitative criteria for phase transition in active support design, and to achieve precise control from experience-based decision-making to data-driven approaches, the process of determining key parameters and initial active support design in S1 is as follows:

[0087] S11: Determination of surrounding rock conditions and key parameters; determination of tunnel depth through geological exploration and laboratory tests. Average unit weight of overlying strata Uniaxial compressive strength of surrounding rock Deformation modulus of surrounding rock Rock mass integrity index, equivalent radius of tunnel This provides a basis for the design of support parameters;

[0088] S12: Design of initial preload of anchor bolt; calculate the initial preload of anchor bolt according to formula (1). ;

[0089] (1);

[0090] In the formula, The yield strength of the anchor rod material; The cross-sectional area of ​​the anchor rod is expressed in meters (m²). 2 ; and These refer to the anchor bolt spacing and row spacing, respectively. The stress adjustment coefficient (usually ranging from 1.5 to 2.5) is used to reflect the rock mass integrity and construction disturbance. This preload is the basis for ensuring the rapid formation of effective active support to balance early loose loads and actively construct a load-bearing arch.

[0091] S13: Determination of the critical deformation rate threshold; estimate the critical deformation rate threshold according to formula (2). ;

[0092] (2);

[0093] In the formula, This is an empirical coefficient that combines engineering analogies and theoretical analysis. This is the effective length of the anchor bolt. The threshold is a unit velocity (e.g., 1 mm / d or 1 m / s). The determination of this threshold needs to be combined with the geological conditions of the specific project and is used as a criterion for subsequent stage transitions. Based on this criterion, it can effectively ensure that intervention measures are implemented at the most effective time.

[0094] In order to effectively suppress early deformation of the surrounding rock, the first stage of S2—the process of immediate active restraint and flexible surface protection—is as follows:

[0095] S21: Construction of high-prestressed anchor bolts / cables; After the tunnel excavation is completed, during the critical window period before the original strength of the surrounding rock has significantly deteriorated, high-strength resin anchoring agents and ultra-high-strength prestressed anchor bolts / cables are used, according to the prestressing force... When combined with hydraulic tensioning equipment to apply high pre-tension force, strong active support is formed, and a compressive stress zone is quickly constructed on the surface of the surrounding rock.

[0096] S22: Flexible protective spraying; On the grid base of the anchor support, C20 / C25 concrete mixed with polypropylene fiber or steel fiber is sprayed to form a protective layer with set flexibility and crack resistance, completing the immediate sealing and preliminary joint support of the surrounding rock surface.

[0097] S23: First-stage system stiffness established; after the completion of the first stage, the support system achieves initial high stiffness. ;

[0098] To achieve the synergistic effect of yielding pressure with flexibility and modifying the surrounding rock with rigidity, and to effectively coordinate the contradiction between deformation control and stress release, the second stage in S3—the coupling process of controllable yielding pressure and surrounding rock modification—is as follows:

[0099] S31: Stage initiation criterion determination; Based on continuous monitoring data of roadway convergence deformation, when the surrounding rock deformation development enters the critical stage of continuous expansion of the plastic zone but has not yet become unstable, determine whether formula (3) and formula (4) are satisfied at the same time; Only when both criteria are satisfied at the same time is it the best time to implement pressure relief and coupled grouting, and the second stage intervention measures can be initiated; When the judgment conditions are met, execute S32, otherwise continue monitoring and take reinforcement measures until the judgment conditions are met;

[0100] (3);

[0101] (4);

[0102] In the formula, The surface convergence velocity of the tunnel;

[0103] S32: Pressure relief device installation; A constant resistance large deformation (NPR) pressure relief device with specific constant resistance characteristics is installed between the anchor bolt / anchor cable tray and the solidified sprayed layer. The constant resistance value of the constant resistance large deformation pressure relief device... Set according to formula (5); constant resistance value The setting ensures that the stress adjustment during the pressure relief stage is carried out in an orderly manner on the basis of the established strong active support, which is the key to realizing the active adjustment of the stiffness of the support system.

[0104] (5);

[0105] In the formula, To allow for the adjustment coefficient, the value should be between 1.2 and 1.8, selected based on the engineering requirements for the stringency of deformation control.

[0106] S33: Grouting reinforcement; Through the pre-set hollow channel of the anchor bolt or a separately arranged special grouting pipe, single-liquid cement grout or cement-water glass double-liquid grout with adjustable gel time is used to perform pressure-controlled grouting reinforcement of the surrounding rock in the fractured or plastic zone outside the anchor bolt anchoring section.

[0107] S34: Second-stage system stiffness adjustment; after pressure relief initiation, the system stiffness is actively adjusted to a lower level. ( This allows for the containment of deformation and the release of energy, while simultaneously utilizing the solidified grout to enhance the self-supporting capacity of the surrounding rock.

[0108] The goal of this stage is to allow the surrounding rock to undergo controlled deformation to release energy while maintaining a high support resistance, and at the same time to enhance the self-supporting capacity of the surrounding rock by using grout solidification.

[0109] To significantly improve the integrity and deformation resistance of the support system, the third stage in S4—rigid structure coordination and load-bearing ring closure—is as follows:

[0110] S41: Stage start-up condition determination; after the second stage pressure relief and grouting measures take effect, the surrounding rock deformation rate shows a significant and continuous downward trend, and reaches the predetermined threshold, this stage is started.

[0111] S42: Installation of retractable U-shaped steel supports; standard-specification retractable U-shaped steel supports are manually erected close to the tunnel wall, with the connecting cables pre-installed according to the design to allow for a specific amount of retraction. To accommodate possible minor deformations in the later stages; the amount of shrinkage must take into account the deformation of the surrounding rock that has already occurred in the early stages, so as to meet the deformation coordination between different support components and avoid stress concentration. The amount of shrinkage is determined according to formula (6). ;

[0112] (6);

[0113] In the formula, A safety reserve factor (range 1.1~1.3) is used to account for uncertainties such as long-term rheology. This refers to the net deformation of the surrounding rock obtained based on monitoring data and released in an orderly manner through the pressure-relief device in the second stage.

[0114] S43: Backfilling; After the support is erected, immediately fill the gap between the support and the roadway wall with C30 fine stone concrete or high-strength precast concrete blocks to ensure that the support is tightly combined with the anchor-grouting reinforcement ring formed in the early stage, without any voids, and to form a collaborative bearing ring with multiple components bearing the force together.

[0115] S44: The system stiffness jumps in the third stage; after the rigid support system is added, the system stiffness jumps to ( ).

[0116] In order to ensure the provision of durable support, in S5, the process of the fourth stage - overall stability and permanent closure is as follows:

[0117] S51: Quantitative evaluation of overall stability; after the collaborative bearing circle formed in the third stage is observed for a period of stable period, its overall stability is quantitatively evaluated. The core is to calculate the overall safety factor of the existing collaborative bearing circle; in the process of quantitative evaluation, the overall safety factor is calculated according to formula (7) , if , then the evaluation is qualified, otherwise reinforcement measures are taken until the re-evaluation is qualified; among them, is the allowable safety factor specified by the design code; this process is a necessary step to ensure the safety and reliability of the main structure before the permanent lining is constructed;

[0118] (7);

[0119] In the formula, , , are the bearing capacities estimated according to the material strength and geometric parameters of the bolt system, grouting reinforcement ring and U-shaped steel support respectively; is the surrounding rock load estimated according to the theory of in-situ stress and plastic zone range;

[0120] S52: Casting of reinforced concrete lining; after the evaluation is qualified, a reinforced concrete lining with reinforcement is integrally cast in the innermost layer. This lining serves as the final safety reserve and durability guarantee, and is firmly combined with the internal collaborative bearing circle to form an integrated permanent support structure with high stiffness and strong integrity;

[0121] S53: Establishment of the final stiffness in the fourth stage; after the fourth stage is completed, the system stiffness reaches the design maximum value ( ).

[0122] The present invention aims at the technical problems of the long-term disconnection between the active and passive supports in terms of time sequence and mechanics and the mismatch between the system stiffness and the dynamic deformation process of the surrounding rock in the control of large deformations in soft rock roadways, and provides a method for integrated active and passive collaborative support based on the perception of the dynamic response of the surrounding rock. By integrating existing mature support technologies such as high-pre-tension bolts, constant-resistance yielding devices, grouting reinforcement, collapsible U-shaped steel supports and concrete linings, an integrated collaborative bearing system is constructed that actively adjusts the stage stiffness according to the real-time deformation feedback of the surrounding rock.

[0123] First, key parameters such as tunnel depth, surrounding rock strength, and deformation modulus are determined through geological exploration and laboratory tests, providing a scientific basis for support design. The initial preload of the anchor bolts is quantitatively determined based on the yield strength of the bolt body and the stress reduction value of the overlying strata, avoiding uncertainties caused by empirical values. The critical deformation rate threshold is determined based on the ratio of surrounding rock strength modulus and the ratio of equivalent radius to effective anchor bolt length, providing clear quantitative criteria for subsequent stage transitions and shifting support decisions from "experience-dependent" to "data-driven."

[0124] Secondly, high-strength anchor bolts / cables are immediately installed and high preload is applied after tunnel excavation to quickly form a compressive stress zone on the surface of the surrounding rock, actively inhibiting early deformation and deterioration. Fiber-reinforced concrete is then sprayed to form a flexible protective layer, which serves to seal the surrounding rock, resist cracking, and cooperate with the anchor bolts in bearing load, achieving "immediate sealing + preliminary combined support." After the first stage is completed, an initial high-rigidity support system is constructed. This lays the foundation for subsequent pressure and reinforcement.

[0125] Subsequently, when the deformation rate meets the set criteria, a constant resistance relief device is installed to actively reduce the stiffness of the support system. This process achieves controllable pressure relief and orderly energy release in the surrounding rock, preventing sudden instability. Simultaneously, grouting reinforces the fractured plastic zone of the surrounding rock, enhancing its self-supporting capacity and creating a dual effect of "relieving pressure with flexibility and modifying its properties with rigidity." This stage achieves synergy between "active weakening" and "surrounding rock strengthening," reconciling the contradiction between controlling deformation and releasing stress.

[0126] Furthermore, after the deformation rate continues to decrease, a collapsible U-shaped steel support is erected and backfilling is carried out to ensure a tight bond between the support and the previously formed anchor-grouting reinforcement ring. This creates a synergistic load-bearing ring where multiple components (anchor bolts, grouting body, and support) share the load, achieving a secondary increase in system stiffness. The compressibility design allows for slight deformation space, avoiding stress concentration and improving the structure's adaptability.

[0127] Finally, after a stability assessment (such as safety factor calculation) confirms that the co-bearing ring meets the requirements, the reinforced concrete lining is poured as a whole to form an integrated permanent support structure with maximum stiffness and strongest integrity. As a final safety reserve and durability guarantee, it ensures the long-term stability of the support system.

[0128] This method establishes dynamic decision criteria based on monitoring indicators such as deformation rate, enabling the overall stiffness of the support system to evolve in a stepwise manner according to the actual development process of surrounding rock deformation. , , , The entire process follows a proactive control logic of actively weakening to release energy and gradually strengthening to build stability. It scientifically coordinates the contradiction between controlling deformation and releasing stress, significantly improving the support system's adaptability to complex surrounding rock conditions. Simultaneously, through quantitative safety calculations and stage transition condition control, it avoids blind and over-strengthening of the support, optimizing material usage while ensuring long-term roadway stability, reducing rework due to support failure, and resulting in significant economic benefits. Based on mature support components and construction techniques, this method provides a standardized and highly operable support operation procedure for soft rock roadways through systematic process integration and quantitative decision support. It reduces over-reliance on individual experience and improves the quality controllability and reliability of support engineering.

[0129] The present invention also provides an integrated active and passive support system for soft rock roadways based on dynamic stiffness control, which is used to realize an integrated active and passive support method for soft rock roadways based on dynamic stiffness control, including a data sensing module, an analysis and decision-making module, and a support execution subsystem;

[0130] The data sensing module includes a laser convergence unit, a multi-point displacement meter, a pressure sensor, and a strain gauge, used to collect multi-source monitoring data;

[0131] The analysis and decision-making module can pre-store multiple sets of decision parameter templates configured for different surrounding rock grades (e.g., Class I to V) and different engineering impact stages (e.g., the initial disturbance period of tunnel excavation, the mining impact period of adjacent working faces). These templates include differentiated threshold parameters (e.g., , , The system receives real-time information from the data sensing module and processes and analyzes it based on the calculation models, formulas, and logical criteria in the support method. This allows for the automatic determination of the current support stage and the generation of quantitative decision-making instructions that include the timing of the next stage's start, key construction parameters (such as target grouting pressure and the set value of the support's retractable size). The system also includes stage transition conditions, enabling preliminary matching of templates based on geological survey data before tunnel excavation. After excavation, the parameters of the selected templates are dynamically fine-tuned and optimized based on real-time monitoring data, providing more accurate and personalized scientific decision support for manual construction and reducing over-reliance on the experience of construction personnel.

[0132] Specifically, the analysis and decision-making module includes a stage identification unit, a key parameter calculation unit, and a decision instruction output unit;

[0133] The stage identification unit is used to determine the current support stage based on the deformation rate and change trend provided by the data sensing module, and output the stage start / conversion command.

[0134] The key parameter calculation unit is used to calculate key design parameters in real time or initially based on geological exploration, indoor test and field monitoring data. Key design parameters include the initial pre-tightening force of the anchor bolt, the critical deformation rate threshold, the constant resistance value of the constant resistance relief device, the reserved shrinkage of the U-shaped steel support and the overall safety factor.

[0135] The decision command output unit is used to receive the judgment results of the stage identification unit and the design values ​​of the key parameter calculation unit, and output specific operation commands to each component of the support execution subsystem. In the first stage, it outputs the anchor bolt preload application value, shotcrete mix ratio and thickness; in the second stage, it outputs the installation timing and constant resistance value of the pressure relief device, grouting pressure and grout type; in the third stage, it outputs the U-shaped steel support erection timing, retractable setting value, and backfill material; in the fourth stage, it outputs the reinforced concrete lining pouring command and safety factor confirmation.

[0136] The support execution subsystem includes a first-stage execution component, a second-stage execution component, a third-stage execution component, and a fourth-stage execution component. The first-stage execution component is used to achieve rapid active support and surface sealing after tunnel excavation, forming an initial high-rigidity system. The second-stage execution component is used to actively reduce the system stiffness to achieve controllable pressure relief, while simultaneously reinforcing the plastic zone of the surrounding rock with pressure grouting to improve the self-supporting capacity of the surrounding rock. The third-stage execution component is used to erect rigid supports and tightly integrate them with the previous anchoring-grouting reinforcement ring to form a synergistic bearing ring, achieving a second leap in system stiffness. The fourth-stage execution component is used to integrally cast reinforced concrete lining in the innermost layer, forming an integrated permanent support structure with the highest stiffness and strongest integrity, serving as the final safety reserve and durability guarantee.

[0137] As a preferred embodiment, the laser convergence device is deployed on the surface of the tunnel to collect the convergence displacement and convergence velocity of the tunnel surface. Therefore, the deformation rate and the timing of stage transitions can be determined; the multi-point displacement gauges are deployed in the deep region of the surrounding rock to collect displacements at different depths within the surrounding rock, thereby determining the depth of the plastic zone boundary and the net deformation of the surrounding rock. The pressure sensor is installed on the anchor bolt tray and U-shaped steel support to collect the bearing capacity of the anchor bolt / anchor cable. The load-bearing capacity and safety factor of the U-shaped steel support are assessed; the strain gauges are installed on the anchor tray and the U-shaped steel support to collect the strain deformation of the support components, so as to monitor the start-up status of the pressure relief device and the retraction of the support.

[0138] To achieve objective quantification and precise control of support phase initiation and switching, avoid subjective misjudgments, and ensure that intervention measures at each stage are executed at the most opportune time, the process by which the phase identification unit determines the current support phase and outputs the phase initiation / switching command is as follows: When simultaneously satisfying... and When the deformation rate shows a significant and continuous decreasing trend and reaches a predetermined threshold, the second stage (controlled pressure relief and grouting) is initiated; when the deformation rate reaches a predetermined threshold, the third stage (rigid support erection) is initiated; after stability assessment, the overall safety factor is determined to be [missing information]. When the time comes, it is determined that the fourth stage (permanent lining pouring) will be initiated.

[0139] In order to achieve standardized and modular configuration of the support process, facilitate rapid on-site construction, and ensure the reliable implementation of technical measures at each stage, the first stage execution components include anchor bolts / anchor cables, high-strength resin anchoring agent, anchor bolt drilling rig (for drilling holes for anchor bolts / anchor cables), hydraulic tensioning equipment (for applying pre-tightening force to anchor bolts / anchor cables), and fiber concrete spraying equipment (for spraying C20 / C25 concrete mixed with polypropylene fibers or steel fibers).

[0140] The second stage execution components include a constant resistance large deformation pressure relief device, a grouting subsystem (including a grouting pump, grouting pipe, sealing device and mixer; the grouting pump is used to inject single-component cement grout or cement-water glass two-component grout with adjustable gel time, and the mixer is used to mix the grout) and grouting materials (single-component cement grout or cement-water glass two-component grout).

[0141] The third-stage execution components include a retractable U-shaped steel support, backfill material, and filling construction equipment (for filling the gap between the support and the roadway wall with C30 fine aggregate concrete or high-strength precast concrete blocks).

[0142] The fourth stage execution components include steel reinforcement (reinforcement skeleton), concrete (for lining, usually not lower than C30), formwork and vibration equipment, and pouring and curing devices.

[0143] In this invention, a data sensing module (laser convergence instrument, multi-point displacement gauge, pressure sensor, strain gauge) facilitates real-time acquisition of multi-source monitoring data, providing accurate and continuous surrounding rock condition information for the analysis and decision-making module. This frees support decisions from reliance on experience and provides a scientific data foundation. The analysis and decision-making module incorporates a stage identification unit, which automatically determines the current support stage based on deformation rate and trend, and outputs stage initiation / transition commands. This upgrades from manual judgment to intelligent identification, ensuring accurate and timely stage transitions. Based on key parameter calculation data, the module can calculate core design parameters such as anchor bolt preload, critical deformation rate threshold, constant resistance, allowable retraction, and safety factor in real-time or initially, using geological survey, laboratory test, and field monitoring data. This allows the support design to dynamically adjust with changes in surrounding rock conditions, avoiding the problems of fixed parameters and poor adaptability in traditional methods. The decision command output unit outputs specific operation commands (such as pre-tightening force value, spraying ratio, pressure relief timing, grouting pressure, support shrinkage, pouring command, etc.) for the four support stages. It can automatically and efficiently convert the analysis results directly into executable construction parameters, providing a scientific reference for subsequent construction.

[0144] The support execution subsystem is divided into four independent components, each corresponding to mature technologies such as high pre-tightening anchor bolts and flexible spraying, constant resistance pressure relief and grouting, U-shaped steel supports and backfilling, and reinforced concrete lining. The timing between each component is clear and the connection is close, realizing the synergistic integration of active and passive support in terms of time and mechanics.

[0145] This system can dynamically adjust the support stiffness and strategy according to the deformation of the surrounding rock. , , , This approach scientifically coordinates the contradiction between deformation control and stress release, improving adaptability to complex soft rock conditions. Simultaneously, quantitative safety calculations ensure safety reserves at each stage, effectively reducing the risk of support failure and significantly enhancing its adaptability and reliability. Furthermore, precise stage-based initiation control and parameter optimization avoid over-support or ineffective repairs, reducing material waste and construction delays, achieving good technical and economic results, and optimizing costs and schedules. Moreover, breaking down the complex soft rock support process into standardized, quantifiable modules and procedures reduces reliance on individual experience, facilitating application in similar projects, improving the quality control of support engineering, promoting standardized operations, and enabling widespread adoption.

Claims

1. A method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation, characterized in that, Includes the following steps: S1: Determination of key parameters and initial active support design; Key parameters were determined through exploration and testing. The initial preload of the anchor was determined based on the yield strength of the rod and the stress reduction value of the overlying rock layer. The critical deformation rate threshold was determined based on the strength modulus ratio of the surrounding rock and the ratio of the equivalent radius to the effective length of the anchor. The process of determining key parameters and designing the initial active support is as follows: S11: Determination of surrounding rock conditions and key parameters; determination of tunnel depth through geological exploration and laboratory tests. Average unit weight of overlying strata Uniaxial compressive strength of surrounding rock Deformation modulus of surrounding rock Rock mass integrity index, equivalent radius of tunnel ; S12: Design of initial preload of anchor bolt; calculate the initial preload of anchor bolt according to formula (1). ; （1）； In the formula, The yield strength of the anchor rod material; The cross-sectional area of ​​the anchor rod; and These refer to the anchor bolt spacing and row spacing, respectively. The stress adjustment coefficient is used to reflect the rock mass integrity and construction disturbance. S13: Determination of the critical deformation rate threshold; estimate the critical deformation rate threshold according to formula (2). ; （2）； In the formula, This is an empirical coefficient that combines engineering analogies and theoretical analysis. This is the effective length of the anchor bolt. Unit speed; S2: Phase One - Immediate Active Constraints and Flexible Surface Protection; After the tunnel is excavated, high-strength anchor bolts / anchor cables are immediately installed according to the design pre-tightening force to form a compressive stress zone on the surface of the surrounding rock. Subsequently, fiber-reinforced concrete is sprayed to form a protective layer with set flexibility and crack resistance, achieving immediate sealing and initial combined support of the surrounding rock surface, and finally constructing an initial high-rigidity support system. S3: Second stage—coupled controllable pressure relief and surrounding rock modification; When the roadway deformation rate meets the set criteria, a constant resistance pressure relief device is installed and the stiffness of the support system is actively reduced to achieve controllable pressure relief and energy release of the surrounding rock. At the same time, the surrounding rock in the fractured plastic zone is reinforced by grouting to enhance the self-supporting capacity of the surrounding rock. S4: Third Stage—Rigid Structure Coordination and Load-Bearing Circle Closure; After the deformation rate continues to decrease, a collapsible U-shaped steel support is erected and backfilling is carried out to make it closely integrated with the anchor-grouting reinforcement ring formed in the early stage, forming a synergistic bearing ring in which multiple components share the force, and realizing a second leap in system stiffness. S5: Phase Four—Overall Stability and Permanent Closure; After the stability assessment confirmed that the safety factor of the collaborative bearing ring met the requirements, the reinforced concrete lining was poured as a whole to form an integrated permanent support structure, so that the system stiffness reached the design maximum value.

2. The method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation according to claim 1, characterized in that, In S2, the first stage—the process of immediate active constraint and flexible surface protection—is as follows: S21: Construction of high-prestressed anchor bolts / cables; After the tunnel excavation is completed, during the critical window period before the original strength of the surrounding rock has significantly deteriorated, high-strength resin anchoring agents and ultra-high-strength prestressed anchor bolts / cables are used, according to the prestressing force... When combined with hydraulic tensioning equipment to apply high pre-tension force, strong active support is formed, and a compressive stress zone is quickly constructed on the surface of the surrounding rock. S22: Flexible protective spraying; On the grid base of the anchor support, C20 / C25 concrete mixed with polypropylene fiber or steel fiber is sprayed to form a protective layer with set flexibility and crack resistance, completing the immediate sealing and preliminary joint support of the surrounding rock surface. S23: First-stage system stiffness established; after the completion of the first stage, the support system achieves initial high stiffness. .

3. The method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation according to claim 2, characterized in that, In S3, the second stage—the coupling process of controlled pressure relief and surrounding rock modification—is as follows: S31: Stage start-up criterion determination; Based on continuous monitoring data of roadway convergence deformation, when the surrounding rock deformation development enters the critical stage of continuous expansion of the plastic zone but has not yet become unstable, determine whether formula (3) and formula (4) are satisfied at the same time; If the determination condition is met, execute S32; otherwise, continue monitoring and take reinforcement measures until the determination condition is met. （3）； （4）； In the formula, The surface convergence velocity of the tunnel; S32: Pressure relief device installation; A constant resistance, large deformation pressure relief device with specific constant resistance characteristics is installed between the anchor bolt / anchor cable tray and the solidified sprayed layer. The constant resistance value of the constant resistance, large deformation pressure relief device is specified. Set according to formula (5); （5）； In the formula, To allow for pressure control coefficient; S33: Grouting reinforcement; Through the pre-set hollow channel of the anchor bolt or a separately arranged special grouting pipe, single-liquid cement grout or cement-water glass double-liquid grout with adjustable gel time is used to perform pressure-controlled grouting reinforcement of the surrounding rock in the fractured or plastic zone outside the anchor bolt anchoring section. S34: Second-stage system stiffness adjustment; after pressure relief initiation, the system stiffness is actively adjusted to a lower level. .

4. The method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation according to claim 3, characterized in that, In S4, the third stage—the process of rigid structure coordination and load-bearing ring closure—is as follows: S41: Stage start-up condition determination; after the second stage pressure relief and grouting measures take effect, the surrounding rock deformation rate shows a significant and continuous downward trend, and reaches the predetermined threshold, this stage is started. S42: Installation of retractable U-shaped steel supports; standard-specification retractable U-shaped steel supports are manually erected close to the tunnel wall, with the connecting cables pre-installed according to the design to allow for a specific amount of retraction. Among them, the shrinkable amount is determined according to formula (6). ; （6）； In the formula, A safety reserve factor is provided to account for uncertainties such as long-term rheology; This refers to the net deformation of the surrounding rock obtained based on monitoring data and released in an orderly manner through the pressure-relief device in the second stage. S43: Backfilling; After the support is erected, immediately fill the gap between the support and the roadway wall with C30 fine stone concrete or high-strength precast concrete blocks to ensure that the support is tightly combined with the anchor-grouting reinforcement ring formed in the early stage, without any voids, and to form a collaborative bearing ring with multiple components bearing the force together. S44: The third stage of system stiffness jump; after the addition of the rigid support system, the system stiffness jumps to... .

5. The method for integrated active and passive support of soft rock roadways based on dynamic stiffness regulation according to claim 4, characterized in that, In S5, the fourth stage—the process of overall stability and permanent closure—is as follows: S51: Quantitative evaluation of overall stability; After the collaborative bearing circle formed in the third stage has been observed for a period of stable period, its overall stability is quantitatively evaluated; In the process of quantitative evaluation, the overall safety factor is calculated according to formula (7). , if , the evaluation is qualified; otherwise, reinforcement measures are taken until the re-evaluation is qualified; where is the allowable safety factor specified by the design code. （7）； In the formula, , , The bearing capacity of the anchor system, grouting reinforcement ring, and U-shaped steel support is estimated based on material strength and geometric parameters, respectively. The surrounding rock load is estimated based on the theory of in-situ stress and plastic zone range; S52: Reinforced concrete lining pouring; After passing the assessment, reinforced concrete lining is poured as a whole in the innermost layer. This lining serves as the final safety reserve and durability guarantee, and is firmly combined with the internal cooperating bearing ring to form an integrated permanent support structure with high rigidity and strong integrity. S53: The final stiffness of the fourth stage is established; after the fourth stage is completed, the system stiffness reaches the design maximum value. .

6. A dynamic stiffness-controlled integrated active and passive support system for soft rock roadways, used to implement the dynamic stiffness-controlled integrated active and passive support method for soft rock roadways as described in claim 5, characterized in that, It includes a data perception module, an analysis and decision-making module, and a support and execution subsystem; The data sensing module includes a laser convergence unit, a multi-point displacement meter, a pressure sensor, and a strain gauge, used to collect multi-source monitoring data; The analysis and decision-making module includes a stage identification unit, a key parameter calculation unit, and a decision instruction output unit. The stage identification unit is used to determine the current support stage based on the deformation rate and change trend provided by the data sensing module, and output the stage start / conversion command. The key parameter calculation unit is used to calculate key design parameters in real time or initially based on geological exploration, indoor test and field monitoring data. Key design parameters include the initial pre-tightening force of the anchor bolt, the critical deformation rate threshold, the constant resistance value of the constant resistance relief device, the reserved shrinkage of the U-shaped steel support and the overall safety factor. The decision command output unit is used to receive the judgment results of the stage identification unit and the design values ​​of the key parameter calculation unit, and output specific operation commands to each component of the support execution subsystem. In the first stage, it outputs the anchor bolt preload application value, shotcrete mix ratio and thickness; in the second stage, it outputs the installation timing and constant resistance value of the pressure relief device, grouting pressure and grout type; in the third stage, it outputs the U-shaped steel support erection timing, retractable setting value, and backfill material; in the fourth stage, it outputs the reinforced concrete lining pouring command and safety factor confirmation. The support execution subsystem includes a first-stage execution component, a second-stage execution component, a third-stage execution component, and a fourth-stage execution component. The first-stage execution component is used to achieve rapid active support and surface sealing after tunnel excavation, forming an initial high-rigidity system. The second-stage execution component is used to actively reduce the system stiffness to achieve controllable pressure relief, while simultaneously reinforcing the plastic zone of the surrounding rock with pressure grouting to improve the self-supporting capacity of the surrounding rock. The third-stage execution component is used to erect rigid supports and tightly integrate them with the previous anchoring-grouting reinforcement ring to form a synergistic bearing ring, achieving a second leap in system stiffness. The fourth-stage execution component is used to integrally cast reinforced concrete lining in the innermost layer, forming an integrated permanent support structure with the greatest stiffness and strongest integrity, serving as the final safety reserve and durability guarantee.

7. The integrated active and passive support system for soft rock roadways based on dynamic stiffness regulation according to claim 6, characterized in that, The laser convergence instrument is deployed on the surface of the tunnel to collect the convergence displacement and convergence velocity of the tunnel surface. The multi-point displacement gauges are deployed in the deep area of ​​the surrounding rock to collect displacement data at different depths within the rock. The pressure sensors are deployed on the anchor bolt tray and U-shaped steel support to collect the bearing capacity of the anchor bolt / anchor cable. The load-bearing capacity of the U-shaped steel support; the strain gauges are installed on the anchor tray and the U-shaped steel support to collect the strain and deformation of the support components.

8. The integrated active and passive support system for soft rock roadways based on dynamic stiffness regulation according to claim 7, characterized in that, The process by which the stage identification unit determines the current support stage and outputs the stage start / transition command is as follows: When the conditions are met simultaneously... and When the deformation rate shows a significant and continuous downward trend and reaches a predetermined threshold, the second stage is initiated; when the deformation rate reaches a predetermined threshold, the third stage is initiated. Based on stability assessment, the overall safety factor is [missing information]. At that time, the fourth stage is initiated.

9. The integrated active and passive support system for soft rock roadways based on dynamic stiffness regulation according to claim 8, characterized in that, The first-stage execution components include anchor bolts / cables, high-strength resin anchoring agent, anchor bolt drilling rig, hydraulic tensioning equipment, and fiber concrete spraying equipment; The second-stage execution components include a constant-resistance large-deformation pressure relief device, a grouting subsystem, and grouting materials; The third-stage execution components include a retractable U-shaped steel support, backfill material, and filling construction equipment; The fourth stage execution components include reinforcing steel, concrete, formwork and vibrating equipment, and pouring and curing devices.

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