Design method of pressure dispersion type pre-stressed anchor cable under karst geology

Abstract

The invention relates to a design method of a pressure dispersion type pre-stressed anchor cable under karst geology. Utilizing geological three-dimensional reconstruction combining CT scanning and high-frequency radar imaging to extract a path obstacle map formed by a karst channel / cavity / fracture zone; identifying a mechanical continuous path by using a graph neural network; a biaxial incongruous elastic modulus material comprising a fiber composite wrapping layer and a macromolecule elastic cavity is implanted into the anchor cable section; designing a specific reverse deformation structure; an expandable closed structure is introduced into the anchor cable penetrating cavity section, and a pressure bearing and stabilizing space is arranged in the structure; a stress damping device is embedded in the closed structure to buffer tension fluctuation of adjacent sections; the pre-stressed anchor cable is provided with multiple stages of tensioning ports or tension adjusting sections, and each section is managed by an independent controller and a sensor; real-time stress feedback judgment based on an FBG optical fiber strain gauge is carried out; tensioning speed, sequence and even pause / slow release are dynamically adjusted according to stress feedback, and main / auxiliary tensioning rhythm is formed.

Description

Technical Field

[0001] The invention relates to a design method for a pressure-dispersed prestressed anchor cable in karst geology. Background Art

[0002] The prestressed anchor cable design method currently used in karst geological environments, although it can meet the requirements of conventional engineering for initial anchoring force to a certain extent, still has many deficiencies and obvious disadvantages in actual application, which seriously restricts the long-term stability, safety and economy of the structure. First, the traditional design method generally relies on a limited number of drill core samples and two-dimensional geological profiles as geological basis, lacks the systematic detection and identification of complex discontinuous structures such as karst channels, hidden cavities, and fracture zones in three-dimensional space, resulting in overly idealized anchor cable layout and path planning, which fails to fully reflect the actual underground geomechanical conditions, and thus leads to the anchor cable system being too unstable. In the actual transmission process, conventional prestressing often encounters empty pulling, interruption or local leakage, and cannot form a continuous and reliable mechanical transmission chain. Secondly, the existing methods basically adopt uniform rigidity, fixed arrangement length and fixed tensioning method in the anchor cable structure design stage, lacking the targeted adaptive design capability for the heterogeneous characteristics of karst geology and local weakened areas. Once the anchor cable path passes through a cavity, dissolution zone or weak fracture zone, the traditional rigid anchor cable structure cannot effectively buffer or absorb energy locally, and it is very easy to form stress concentration locally, resulting in early damage of the anchor cable or loosening of the anchor end, which seriously threatens the integrity and safety of the overall support structure.

[0003] Furthermore, the current conventional tensioning control methods mostly adopt overall tensioning or limited staged tensioning strategies, but overall lack a dynamic rhythm adjustment mechanism based on real-time force feedback. The actual forces on each section of the anchor cable during the tensioning process are significantly different. Some sections may experience advanced stress, local cracking or even shearing, while other sections may be delayed and become useless. Traditional methods are unable to identify the differences in the stress states of each section in real time, and are even unable to flexibly adjust the tensioning sequence, tensioning rate or perform local pauses and releases based on real-time monitoring results, resulting in a serious imbalance in the internal force distribution of the entire anchoring system and a significant reduction in the stress dispersion effect. At the same time, existing monitoring methods are generally lagging behind. Traditional methods that rely on cross-sectional observations, manual testing, etc. are not only sparse in data and have large delays, but also difficult to timely capture local mutations in the anchor cable stress process. Once a small disturbance or sudden change in the surrounding rock occurs within the karst geology, conventional monitoring systems are often unable to respond and issue warnings in a timely manner, causing the anchor system to miss the window period for timely adjustment and remediation.

[0004] In addition, in terms of risk identification, the current prestressed anchor cable construction in karst geological environments usually lacks an effective spatial risk distribution quantitative analysis system, and cannot carry out scientific anchor cable segmentation design and buffer section layout based on path connectivity and local weak area agglomeration, resulting in high-risk areas unable to be effectively mitigated and supported. In the later operation stage, engineering accidents such as anchor cable loosening, lining cracking, and even overall deformation and instability frequently occur. On the other hand, for cavity crossing areas, existing designs often simply thicken the anchor cable or increase the grouting volume in an attempt to reinforce it, but lack systematic consideration of the stress interruption and stability failure that may occur in the process of the anchor cable crossing the cavity. Simply increasing the anchor cable cross-section or grouting volume not only cannot fundamentally solve the problem of force flow continuity, but may lead to new stress concentration areas due to local stiffness mutations, inducing secondary damage inside the structure, resulting in serious consequences. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for designing a pressure-dispersed prestressed anchor cable under karst geology, thereby solving some of the drawbacks and deficiencies pointed out in the background technology.

[0006] The present invention solves the above-mentioned technical problems by adopting the following technical solutions: A method for designing a pressure-dispersed prestressed anchor cable in karst geology, comprising: S1, using dynamic identification of the prestressing action path:

[0007] S1.1. Using geological 3D reconstruction combined with CT scanning and high-frequency radar imaging, we extract the path obstacle map composed of karst channels, cavities, and fracture zones;

[0008] S1.2. Apply graph neural networks to identify mechanical continuity paths: Identify spatial points where prestress transfer predictions may be cut off, bend, or leak; map these points to stress risk nodes, which serve as input for subsequent anchor cable structure variation and tensioning logic adjustments.

[0009] S2, using pressure anisotropic response regulation mechanism:

[0010] S2.1. Implant a biaxial anisotropic elastic modulus material comprising a fiber composite cladding and a polymer elastic cavity in the anchor cable segment;

[0011] S2.2. Design a specific reverse deformation structure. When encountering a cavity or fracture zone in a certain direction, the anchor cable will undergo local pre-buckling / buffering deformation, actively guiding the stress to be transferred to the higher load-bearing area;

[0012] S3. Use a controllable load-bearing closure mechanism in the cavity spanning section:

[0013] S3.1. Introduce an expandable closed structure, including an intelligent foam core / micro-pressure tension bladder, in the section where the anchor cable passes through the cavity. Arrange the structure to inherit pressure and stabilize the space: after expansion, the structure adheres to the cavity boundary, absorbs surrounding deformation, and forms a local force field.

[0014] S3.2, the closed structure has embedded stress damping devices to buffer the tension fluctuations of adjacent sections;

[0015] S4, tension and release coordinated control algorithm and segment-level active feedback strategy:

[0016] S4.1. Prestressed anchor cables are equipped with multiple tensioning ports or tension adjustment segments, each segment being managed by an independent controller and sensor;

[0017] S4.2. Based on real-time stress feedback including FBG fiber optic strain gauges, determine which section has stress concentration and which section is not subjected to stress; dynamically adjust the tensioning rate, sequence, and even pause / release according to the force feedback to form a main / auxiliary tensioning rhythm.

[0018] Furthermore, the method for dynamic identification of prestress action path:

[0019] CT scan images are collected to obtain data on density variations within the rock mass, reflecting porosity, cavity boundaries, and overall material strength attenuation. High-frequency geological radar (GPR) is also used to detect electromagnetic reflectivity to identify potential discontinuous interfaces, fracture zones, and hidden dissolution structures. These two signals, representing material solidity and interface reflectivity, respectively, are mapped to a unified geological integrity index through a fusion algorithm, defined as follows:

[0020]

[0021] in:

[0022] μ ijk is the comprehensive mechanical integrity index of the cell (i, j, k), which is used to describe the mechanical continuity of the rock mass at that location when bearing prestress; ρ ijk is the density response value obtained by CT scanning, reflecting the solidity and cavity distribution of the local rock mass; γ ijk is the gradient value of the GPR reflection signal, reflecting the discontinuity of the rock interface; is the normal vector of the radar wave propagation direction; φ1(·) is the nonlinear mapping function that converts the density signal into the integrity score; φ2(·) is the nonlinear mapping function that converts the reflection signal into the fragmentation score; To calculate the reflectivity change rate along the radar wave direction and characterize the degree of interface mutation; β is the weight coefficient for adjusting directional sensitivity.

[0023] Furthermore, the method for dynamic identification of prestress action path:

[0024] In the reconstructed 3D model, the connection paths between each unit need to be evaluated for mechanical connectivity. That is, during the actual tensioning process, whether the prestress is transferred from the anchor segment through the region to another segment. The 3D grid structure is abstracted into a graph structure G = (N, E), where nodes B represent spatial units and edges E represent potential stress paths. The following weights are defined:

[0025]

[0026] in:

[0027] Ω mn is the feasibility weight of prestress transfer between node m and node n; μ m ,μ n Score the mechanical integrity of nodes m and n respectively; is the coordinate vector of nodes m and n in three-dimensional space; is the spatial distance between two nodes; Θ is the penalty function for path direction change. When the path curvature exceeds the set threshold Δ, an additional penalty is given, indicating that the continuity of path force transmission decreases. κ is the penalty coefficient, which is used to adjust the impact of path direction deviation on the overall weight.

[0028] By calculating Ω for each pair of adjacent units mn , construct a complete mechanical feasible path map; in the subsequent tensioning, the stress is preferentially along the high Ω mn The path diffusion, while low Ω mn There is a risk of power transmission interruption or leakage in the area.

[0029] Furthermore, the method for dynamic identification of prestress action path:

[0030] Cluster analysis is performed to analyze the clustering of paths in space. If multiple failure paths appear in a certain spatial area, the area is determined to be a potential anchor failure area, i.e., a stress risk node set. The spatial risk response function is defined as As shown below:

[0031]

[0032] in:

[0033] Any point in three-dimensional space The local stress risk response degree; S is the set of all identified high-risk nodes; is the spatial location of the risk node; For nodes The risk weight reflects the degree of local fracture or force transmission risk; is a three-dimensional pulse function, only The value is 1 when the risk is high, and 0 otherwise, which is used to express the local risk focusing effect.

[0034] Furthermore, the calculation of each position in the space Draw a risk density distribution map. When the risk response of a certain area is higher than the set threshold χ0, make the following design adjustments:

[0035] P1. This section of anchor cable adopts flexible buffer section;

[0036] P2, adjust the tensioning time and force rate of the section;

[0037] P3, enter the cavity relay structure or secondary anchor point.

[0038] Furthermore, the tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include:

[0039] During the design phase of the anchor cable structure, a segmented controllable force application strategy is adopted to divide the anchor cable into several functional sections. Each section is independently equipped with a tensioning port and an adjustable force application mechanism, so that each section has the ability to independently control the prestressing loading. The prestressing level of each section is dynamically allocated according to the geological environment and structural requirements. The segmented prestressing value is defined by the following formula:

[0040]

[0041] in:

[0042] P i is the prestress value required for the functional unit in the i-th section; Λ(·) is the prestress distribution mapping function, which integrates the local force demand, spatial scale and direction factors; σ i Estimated local bearing capacity requirement for this section; d i is the minimum effective anchoring distance between the anchor cable and the rock wall; θ i is the angle between the anchor cable and the vertical direction; α1, α2, α3 are weighted coefficients of different influencing factors; γ, δ are exponential coefficients for adjusting the nonlinear growth characteristics of local force; cos(θ i ) is used to correct the impact of changes in force direction on the overall force transmission performance.

[0043] Furthermore, the tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include:

[0044] A high-frequency dynamic monitoring system based on FBG fiber optic strain gauges is embedded in each functional segment. By collecting data on the strain changes of each segment of anchor cable over time in real time, the process of prestress diffusion can be grasped, whether the force transmission is uniform can be judged, and sections with abnormal concentration or no force can be identified. During the monitoring phase, the cumulative response of the force change of each segment of anchor cable, R, is defined.i , to comprehensively evaluate the strain growth rate and cumulative strength, the expression is:

[0045]

[0046] in:

[0047] R i represents the total cumulative force response of the i-th anchor cable from the start of tensioning to the current moment; ε i (t) represents the instantaneous strain value of the i-th anchor cable at time t; is the rate of change of the strain of the anchor cable over time; Φ(·) is the nonlinear response characteristic function, which is used to couple the combined effects of the strain growth rate and the cumulative strain amplitude on the force contribution; t0 is the starting time point of tensioning; and t is the current monitoring time point.

[0048] Furthermore, the tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include:

[0049] Adopt dynamic tensioning rhythm optimization and control mechanism; in tensioning operation, according to the cumulative force response R of each segment i and the overall tensioning process offset η i (t), real-time adjustment of the tensioning rate v of each segment i (t) to coordinate the force pace of each section; the dynamic control relationship of tensioning rate is defined as follows:

[0050]

[0051] in:

[0052] v i (t) is the actual tension rate of the i-th functional unit at time t; R i (t) is the cumulative force response value of the segment at the current moment; η i (t) is the synchronization offset of the i-th segment relative to the overall tensioning process; Ψ(·) is the tensioning rhythm control function, which comprehensively controls the tensioning rate of each segment; ζ1,ζ2 are the force response and synchronization adjustment weight coefficients respectively; λ1,λ2 are the force response rate sensitivity adjustment parameters and synchronization period adjustment parameters respectively; is an exponential inhibition term, which controls the tension rate of the section with too fast a force increase; sin(λ2η i (t)) is a periodic sinusoidal adjustment term used to balance the synchronization between different segments.

[0053] The beneficial effects of the present invention are as follows: First, by introducing CT scanning and high-frequency geological radar imaging technology, combined with a nonlinear fusion algorithm to reconstruct the geological three-dimensional model and quantitatively evaluate the mechanical integrity indicators, it is possible to accurately identify and dynamically update karst channels, hidden cavities, and fracture zones, greatly improving the accuracy of geological condition assessment and the reliability of prestressed stress transfer path identification; second, by using graph neural networks to perform mechanical connectivity analysis on the three-dimensional geological model, a stress conduction prediction system based on path obstacle maps was established, which can effectively identify potential breaking points, cavity corners, and leakage risk areas, significantly improving the rationality and foresight of anchor system layout and structural design;

[0054] Furthermore, the innovative design of segmented controllable tensioning unit and dynamic force feedback control mechanism are introduced. By setting up multi-level independent tensioning ports and embedding FBG optical fiber strain gauges inside the anchor cable, the force changes of each segment are monitored in real time. Based on the cumulative force response R i Synchronicity offset η i Dynamically adjust the tensioning rate v of each section i (t), the overall anchoring system realizes the intelligent rhythm optimization of the priority of the tensioning section and the synchronous advancement of the auxiliary tensioning section, effectively preventing the local stress over-limit and empty tensioning phenomenon; at the same time, the present invention uses the spatial risk response function A risk distribution map was drawn up, and multiple collaborative design measures were implemented in high-risk areas, including the introduction of flexible buffer sections, tensioning and release adjustments, and cavity relay anchoring. This dispersed the risk of prestressed concentration at the source and greatly improved the adaptability, continuity, and long-term service reliability of the anchor system in karst geological environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The present invention is a flow chart of a method for designing a pressure-dispersed prestressed anchor cable in karst geology.

[0056] Figure 2 This is a flow chart of the method for dynamically identifying the prestressing action path of the present invention.

[0057] Figure 3 This is a flow chart of the method for constructing the tensioning and release collaborative control algorithm and the segment-level active feedback strategy of the present invention. DETAILED DESCRIPTION

[0058] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0059] Participation amount Figure 1The present invention provides a method for designing a pressure-dispersed prestressed anchor cable under karst geology. The method first includes step S1, which adopts a dynamic identification mechanism of the prestressed action path to address the problem of stress concentration and failure of the traditional anchoring system caused by the development of rock cavities and poor mechanical continuity in karst geology. In step S1.1, first, based on the combination of CT scanning and high-frequency geological radar imaging technology, a multi-source geological survey of the anchoring area is carried out. The rock density change information is obtained by CT scanning, and low-density or low-continuity structures such as internal cavities, cracks, and broken zones are identified. At the same time, the electromagnetic reflection abnormality area is captured by high-frequency geological radar imaging to detect hidden dissolution, broken areas and discontinuous interfaces. The two detection results are uniformly mapped to the same three-dimensional coordinate system, and a high-resolution geological three-dimensional stereo model is reconstructed through spatial point cloud fusion and reflection signal fusion algorithms. On this basis, the karst channel, cavity distribution, broken zone extension and morphological information are extracted to form a path obstacle map describing the internal obstacle characteristics of the karst geology. The map not only reflects the weak areas of the rock physics, but also provides a basic geological background for subsequent stress path analysis. Then In step S1.2, based on the path obstacle map constructed above, a graph neural network is applied to perform mechanical continuous path identification and analysis. The geological three-dimensional model is discretized into a graph structure of nodes and edges, where nodes represent spatial units and edges represent potential stress transmission paths. The graph neural network uses node attributes (such as density and continuity index) and edge attributes (such as distance and directional consistency) to perform feature extraction and relationship reasoning. The training model identifies which paths can effectively transmit prestress and which paths have a high fracture risk or mechanical interruption trend, and then determines the locations where cuts, turns, leaks, and other phenomena occur during the prestress transmission process. The system marks these high-risk prediction points as stress risk nodes and maps their spatial coordinates with associated information to output, providing a decision-making basis for subsequent prestressed anchor cable structure layout, flexible segment setting, tensioning sequence, and rhythm optimization.

[0060] In step S2, a pressure anisotropic response adjustment mechanism is adopted to cope with the problems of complex rock structure and drastic changes in bearing capacity in karst geology, and active stress dispersion and guidance is achieved by making the anchor cable have different mechanical adaptability in different directions; in step S2.1, a composite material with biaxial anisotropic elastic modulus characteristics is implanted in different sections of the prestressed anchor cable. The material is composed of a fiber composite cladding and an internal polymer elastic cavity. The fiber composite cladding is arranged along the main axis of the anchor cable, providing high longitudinal strength and stiffness, while the polymer elastic cavity is arranged along the radial direction or a specific transverse direction of the anchor cable, giving the anchor cable lower stiffness and higher elastic deformation capacity in the transverse direction. Through this rigid-flexible anisotropic combination, the anchor cable body can flexibly respond to abnormal geological structures in the transverse direction while maintaining sufficient bearing capacity in the longitudinal direction. In step S2.2, based on the above-mentioned biaxial anisotropic material properties, a specific reverse deformation structure is further designed, that is, a local prefabricated elastic weakened zone or buckling inducing device is set inside the anchor cable, so that when encountering a cavity, a broken zone or a weak interlayer in a certain direction, the anchor cable can undergo controlled pre-buckling deformation or buffering deformation locally in that direction, forming a local bending or expansion and contraction phenomenon. This deformation can not only absorb part of the sudden load energy, but also actively change the prestress transmission path, guiding the force flow to actively transfer from the weak area to the surrounding high-bearing area or continuous rock area, avoiding the prestress from directly passing through the low-bearing area and failing, thereby realizing the intelligent adaptation of the mechanical response of the anchor cable and active pressure dispersion in the complex karst environment, greatly improving the safety and stability of the overall anchoring system under discontinuous geological conditions.

[0061] In step S3, a controllable load-bearing closure mechanism is adopted in the cavity crossing section. To solve the problems of traditional anchor failure and mechanical interruption when the anchor cable crosses the karst cavity, an adjustable and expandable closure device is locally implanted in the anchor cable structure to achieve stress relay transmission and spatial stability. In step S3.1, an expandable closure structure is set inside the area where the anchor cable crosses the identified cavity section. The structure can be composed of an intelligent foam core or a micro-air pressure tension capsule. The intelligent foam core has controlled expansion and consolidation properties and can expand and fill the cavity under preset triggering conditions to form a support interface with a high degree of fit with the cavity boundary. The micro-air pressure tension capsule is adjusted by internal micro-pressure and expands moderately after being stressed to adapt to the shape of cavities of different sizes and shapes. After the closure structure is unfolded and expanded, a load-bearing relay area and a force field stability zone can be formed locally inside the cavity. This area is connected to the cavity. By fitting the cavity boundary, the deformation energy of the surrounding surrounding rock is absorbed, and the adverse effects of the discontinuous space on the prestress transmission of the anchor cable are offset, thereby establishing a local stable support in the cavity area and ensuring that the prestress of the anchor cable can be continuously transmitted; in step S3.2, in order to further improve the mechanical properties of the cavity span section, a stress damping device is synchronously embedded in the expansion closed structure. The damping device can be made of high-viscosity material, micro energy dissipation module or deformation buffer unit, which can effectively buffer the tension fluctuations between the two end sections of the anchor cable during tensioning and use, absorb stress shocks or sudden changes caused by geological changes, surrounding rock squeezing or construction disturbances, and prevent the concentrated transmission of tension to the weak area of the cavity, causing local damage, thereby further improving the stability, ductility and durability of the overall anchor cable system in the cavity area, and ensuring the continuity and reliability of prestress transmission in the complex karst environment.

[0062] In step S4, a tensioning and slow-release coordinated control algorithm and a segment-level active feedback strategy are set up to address the problems of obvious differences in the stress responses of anchor cables in different segments and difficulty in balancing the overall tensioning in complex karst environments, and to achieve the optimal overall performance of the anchoring system through real-time monitoring and dynamic adjustment. In step S4.1, multi-level tensioning ports are reasonably divided on the prestressed anchor cable body or tension adjustment segments are set. Each tensioning port or segment is equipped with an independent tensioning controller and a dedicated stress sensor, so that the anchor cable can independently apply, adjust and monitor the prestressed state according to the segment, and each control unit can respond and execute instructions independently according to the actual stress conditions, thereby having refined tensioning control capabilities. In step S4.2, the real-time stress state of each segment of the anchor cable is continuously monitored by an embedded sensing system, and FBG fiber optic strain gauges are preferably used as the main monitoring means. FBG fiber optic strain gauges can capture the strain change data generated by each segment of the anchor cable during the tensioning process with high frequency and high precision. The system compares the strain change data of each segment of the anchor cable with the strain change data of each segment of the anchor cable with high frequency and high precision. The system dynamically responds to strain and determines in real time which sections experience stress concentration, where force values rise rapidly or reach abnormally high levels, and which sections do not effectively participate in stress loading, where force values change slowly or grow with lag. Based on this dynamic stress feedback, the system then implements active tensioning strategy adjustments. For stress concentration areas, it reduces the tensioning rate, suspends tensioning, or performs local prestress relief to prevent premature instability of local anchor cables or rock failure. For lagging sections that do not participate in stress loading, it appropriately accelerates the tensioning progress or increases the applied prestress value to encourage all sections to participate synchronously in the overall stress loading process. Furthermore, based on the global strain distribution, the system intelligently optimizes the tensioning sequence and flexibly arranges the tensioning order of different sections, forming a coordinated tensioning rhythm with the sections receiving reasonable stress as the primary tensioning sections and the sections requiring compensation as the auxiliary tensioning sections. Through continuous dynamic adjustment and an adaptive relief mechanism, it ultimately achieves a comprehensive improvement in pressure dispersion, force balance, and anchoring safety for prestressed anchor cables in the complex geological environment of karst.

[0063] Example 1:

[0064] Combined with attachment Figure 2 In this example, a mountain highway tunnel project was conducted. The geological conditions along the project line exhibited typical karst development, with dense and irregularly distributed underground caves and fissures. Traditional monolithic tensioned anchor cable construction repeatedly experienced stress concentration, empty tension, and through-the-air failure, seriously impacting the structural safety of the tunnel lining. To address this engineering challenge, a CT scanner was first used to perform high-resolution geological imaging along the anchor cable layout area, following the steps for dynamic identification of the prestressing action path. Three-dimensional density change data was collected at intervals of 0.5 meters. The data revealed the CT density response value ρ for a typical solid rock area. ijk About 2.5g / cm 3 , abnormal low-density areas appear locally, with the lowest value dropping to 1.4g / cm3 , preliminarily determined to be a cavity or a broken zone, and at the same time, the same area was scanned by GPR high-frequency geological radar to obtain electromagnetic reflection intensity data γ ijk In the intact rock mass area, the reflection gradient changes gently, with a typical value of about 10-20%, while in the dissolved area, the reflection gradient changes sharply, reaching more than 50%, indicating the existence of significant interface discontinuity. Subsequently, the CT and GPR data are superimposed and mapped to a unified mechanical integrity index μ by fusion algorithm processing. ijk During the calculation process, the formula proposed by the present invention is adopted:

[0065]

[0066] Specifically, φ1(ρ ijk ) uses a logarithmic nonlinear mapping method, defined as φ1(ρ ijk )=3log(ρ ijk ), mapping entity density to completeness score, φ2(γ ijk ) uses an exponential decay mapping, defined as Reflects the negative impact of fragmentation on integrity, where mapping coefficients 3 and 5 are calibrated through pre-experimental calibration in the project area, and the direction change rate function By taking the gradient change of radar reflection intensity along the radar propagation direction, it is defined as The gradient value is expressed in % / m, representing the percentage change in reflectance per meter. The weight coefficient β ranges from 0.5 to 1.5 in this project and is adjusted based on the severity of the measured geological discontinuity. In this example, the median value β = 1.0 is taken to account for sensitivity to directional changes.

[0067] Taking a typical cell i, j, k as an example, the measured CT density response value ρ ijk =1.6g / cm 3 , GPR reflection gradient change γ ijk =55%, the reflection change rate along the radar direction Substituting each meter into the above mapping function yields the following calculation:

[0068] φ1(ρ ijk )=3log(1.6)≈1.37

[0069] φ2(γ ijk )=5e -0.05×55 ≈5e -2.75 ≈0.32

[0070]

[0071] Finally, we can conclude that:

[0072] μ ijk=1.37+0.32+1.0×22=23.69

[0073] Through the above calculations, it can be concluded that the comprehensive mechanical integrity index of this cell is low, far below the standard value of 30-40 in the normal range of intact rock areas, and it is determined that there is a risk of serious cavity or fracture zone. Therefore, in the subsequent anchor cable design, this location is marked as a high-risk stress node, requiring flexible section design or pressure relief treatment; further, in the three-dimensional distribution map drawn by the mechanical integrity index of the entire area, multiple low-integrity areas and discontinuous zones are clearly identified. Combined with graph neural network reasoning, the optimal stress transfer path planning avoids the above-mentioned high-risk nodes, and redefines the anchor end layout points and tensioning direction of the anchor cable to ensure that the prestress can be gradually diffused and transmitted along the area with good mechanical continuity; in the example, after dynamic identification and path optimization, the final prestressed anchor cable system achieved uniform distribution of local tensioning force during the construction phase, and the maximum local stress deviation of the overall anchor cable system was reduced by about 37%, effectively avoiding the concentrated fracture, empty pulling and failure of anchor cables that were common in karst tunnels in the past, greatly improving the project construction safety and structural service life.

[0074] After completing the reconstruction of the 3D geological model of the karst tunnel project and the comprehensive mechanical integrity index μ of each cell, ijk After the calculations, the project team entered the next phase: dynamic identification and analysis of prestressing paths. In this step, according to the method of the present invention, the three-dimensional geological grid structure of the entire anchoring area was first abstracted into a graph structure G = (N, E), where the node N corresponds to each spatial grid cell and the edge E represents the potential prestressing path between adjacent cells. To quantify the force transmission capacity between each pair of nodes, the following weight calculation formula was used:

[0075]

[0076] where Ω mn is the feasibility weight of prestress transfer between node m and node n, μ m and μ n are the comprehensive mechanical integrity indices of nodes m and n, and is the three-dimensional space coordinate of the node, is the actual spatial distance between the two nodes, Θ is the path direction change penalty function, which is used to express the attenuation effect on the weight when the path curvature or direction deviation exceeds the set threshold Δ, and κ is the path penalty sensitivity coefficient. In this project, the value of κ ranges from 0.1 to 0.5. A low value corresponds to a high tolerance for path direction changes, and a high value corresponds to a greater sensitivity to curvature changes. In this example, κ = 0.3 is selected, and the value of Δ is set between 10° and 20° according to the design specification. In this example, Δ = 15° is taken as the allowable threshold for path curvature changes.

[0077] Taking a typical node pair m, n as an example, node m is located in a dense rock unit, and μ is measured. m =35.2, node n is located in its adjacent unit, and there is a small-scale crack locally. The measured μ n =28.5, and their spatial coordinates are Mihe Meters, calculate the Euclidean distance between two nodes:

[0078]

[0079] The deviation angle between the line connecting the two nodes and the direction of the surrounding principal stress is set to 12°, which is less than the set Δ=15°. The value is defined as a linear decreasing relationship when the deviation angle is less than Δ. The specific value formula is: Substitution Finally, the feasibility weight of force transmission between nodes m and n is calculated by substituting various parameters:

[0080]

[0081] The feasibility weight Ω of prestress transfer between nodes m and n is obtained through this calculation. mn ≈24.21, which belongs to the higher feasibility range, indicating that the prestress can be effectively diffused through this path to form a continuous stress channel. In comparison, in other areas such as a cavity edge cell, its mechanical integrity index μ m =14.8, adjacent unit μ n =11.2, and the spatial direction deviation angle reaches 26°, exceeding the set threshold Δ=15°. In this case, the path penalty function Θ is directly taken as 1, that is, severe penalty, and κ is still taken as 0.3. Substituting into the formula, we get:

[0082]

[0083] This value is significantly lower than the safe force transmission feasibility benchmark of 20 points. Therefore, this area is marked as a high-risk area for force transmission interruption and is not recommended as the main diffusion path. It must be avoided through structural design or the setting of a flexible transition section.

[0084] Through the Ω of each node pair in the whole area mn Calculation, this project has formed a complete mechanical feasible path map, the system prefers high Ω mn The paths are connected in series to form the main force transmission skeleton, and at low Ω mn The area was compensated by introducing flexible buffer sections and relay support structures, and the path continuity index of the optimized anchor system was finally improved by about 29%.

[0085] After completing the dynamic identification of prestressed force transmission path and mechanical feasibility weight Ω in the karst tunnel project mn After the calculation, the project team continued to perform further cluster analysis on the path clustering according to the method of the present invention to identify potential stress risk concentration areas. mn The low threshold filtering rule of the value will set all Ω mn Path edges with less than 10 are marked as breaking paths. Clustering is then performed based on the spatial distribution of node positions to form multiple high-density breaking path clusters. Combined with the actual data from the project site, a total of 7 high-density breaking path areas were identified, of which the largest high-risk area is approximately 4.8m 2 , distributed in the left rear area of the tunnel vault, it is preliminarily determined that there is a hidden large cavity structure there. In order to more accurately quantify the danger level of each potential risk area, this paper introduces the spatial risk response function To perform the calculation, the function is defined as follows:

[0086]

[0087] in For any point in space The local stress risk response degree, S is the set of identified high-risk nodes, is the spatial coordinate of each node in the set, is the risk weight of the node. The value range is set between 0.5 and 2.0, where 0.5 represents a slightly fractured weak area and 2.0 represents a severely fractured or cavity-high risk area. The risk weight is based on the Ω around the node. mn Comprehensive judgment based on average value and geological measurements, is a three-dimensional pulse function, only The value is 1 when the risk is high, and 0 at other locations, reflecting the local concentration of risks.

[0088] In the example calculation process, a key inspection unit in the rear area of the tunnel vault is selected, and the center coordinates are A total of 15 high-risk nodes were detected within 3 meters, of which 9 nodes were If it is greater than 1.5, it belongs to a high-risk weight node. Substituting it into the above formula for integral superposition, the total risk responsiveness of the cell is obtained as:

[0089]

[0090] According to the risk response threshold χ0 set by the present invention, the value range of general projects is set between 10 and 15, which depends on the overall geological fragmentation and the redundancy of the anchor system. The geological conditions of this project are relatively complex, so χ0 = 12 is taken as the risk zone boundary. Therefore, the calculated results are The unit and surrounding area are determined to be a serious potential anchor failure area and must be subject to special structural optimization treatment. Subsequently, according to the design adjustment measures specified in the present invention, the following steps are implemented in sequence:

[0091] First, according to P1 measures, flexible buffer sections were introduced into the anchor cable structure in the risk area. Composite anchor cable sections made of highly elastic steel strands coated with a polymer rubber layer replaced the original fully rigid anchor cable sections. The flexible sections were approximately 2.5 meters long, accounting for 15% of the total anchor length. This significantly improved the energy absorption and deformation adaptability of the local section.

[0092] Secondly, according to the P2 measure, the tensioning time and force application rate were adjusted. During the construction process, the flexible anchor cables in the risk section were delayed for 5 hours, and the tensioning rate was reduced from the conventional 2mm / min to 1mm / min to ensure that the stress in the risk area was gradually and evenly distributed, avoiding sudden tension that would cause surrounding rock instability.

[0093] Finally, according to the P3 measure, a relay structure is implanted in the identified cavity area, and a secondary anchor point is added to the anchor path in the area with the greatest risk. By setting up a combination structure of grouting expansion balls and cavity support plates, an intermediate inheritance carrier is formed to ensure that even if the main anchor point is restricted, the continuous transmission and dispersion of the anchor force can still be achieved.

[0094] After the above series of The design adjustments guided by risk responsiveness and subsequent tensioning monitoring data showed that in areas originally predicted to have the risk of empty tension or failure, the maximum strain difference of each section of the anchor cable decreased by about 42% during actual tensioning. The overall prestress distribution of the anchor cable system became more uniform, and the number of stress mutation points was reduced by 3. The structural deformation monitoring value of the tunnel vault section remained within 5mm within 6 months, which was far below the design warning value of 15mm. This fully verifies that the method of the present invention through spatial risk responsiveness identification and zoning design adjustment is highly feasible and has significant application value in complex karst environments.

[0095] Example 2:

[0096] Combined with attachment Figure 3After completing spatial risk identification and anchor cable path planning in the karst tunnel project, the project team entered the specific application stage based on the tensioning and release coordinated control algorithm and segment-level active feedback strategy proposed in this invention. To adapt to the differences in the stress requirements of different geological units, this project adopted a segmented controllable force application strategy in the anchor cable structure design stage. A 12-meter-long anchor cable was divided into four functional segments, each with a length of 2.5 meters, 3 meters, 3.5 meters, and 3 meters. Each segment is independently equipped with a tensioning port and an adjustable force application mechanism, which can flexibly apply different levels of prestress according to the local geological environment and structural requirements. The prestressing level of each segment is dynamically allocated according to the following mapping formula:

[0097]

[0098] Among them, P i is the prestress value required for the functional unit of the i-th segment, Λ(·) is the comprehensive mapping function designed by the present invention, σ i is the local bearing capacity requirement of each section, in MPa, determined based on 3D geological modeling and inverse mechanical analysis, d i The minimum effective anchoring distance between the anchor cable and the rock wall, in meters, is verified by drilling and exploration. i is the angle between the main axis of the anchor cable and the vertical direction, in degrees, obtained through actual measurement; the weight coefficients α1, α2, and α3 represent the influence weights of force demand, geometric scale, and directional adaptability, respectively. In this project, the value ranges are set to α1 = 0.6 ~ 0.8, α2 = 0.3 ~ 0.5, and α3 = 5 ~ 10. The exponential coefficients γ and δ control the nonlinear increase and decrease characteristics of local influences. In this project, γ = 1.2 and δ = 1.1, respectively, which can reflect the need for fine-tuning the amount of prestressing due to geological heterogeneity.

[0099] Calculation: The geological conditions of the first anchor section area are partially intact rock mass, the bearing capacity requirement σ1 = 12 MPa, the effective anchoring distance d1 = 2.1 m, the angle θ1 = 10°, and the parameters α1 = 0.7, α2 = 0.4, and α3 = 7 are substituted for the calculation, and the first result is:

[0100]

[0101] α3·cos(θ1)=7×cos(10°)≈7×0.9848≈6.8936

[0102] The final calculation results show that the prestressing force of the first section is:

[0103] P1=14.40+0.924+6.8936=22.2176Unit: kN

[0104] Similarly, the second section of anchor cable is located in the transition zone of the partial fracture zone, with a bearing capacity requirement of σ2 = 9 MPa, an anchoring distance of d2 = 1.8 m, and an angle of θ2 = 5°. Substituting the same parameters, we get:

[0105]

[0106] α3·cos(θ2)=7×cos(5°)≈7×0.9962≈6.9734

[0107] The final calculation is:

[0108] P2=9.758+0.756+6.9734=17.4874Unit: kN

[0109] The above calculations lead to the reasonable distribution of prestress values in different sections. During the actual construction process, the project team strictly followed the P i The invention adopts the segment-level autonomous tensioning control method to realize the overall synchronization of strain curves of various functional segments, and the maximum asynchronous strain deviation of adjacent segments is reduced to 1.2%, which is much lower than the deviation level of 3.8% under the traditional unified tensioning method. The tensioning efficiency of the overall anchoring system is improved by about 25%, which effectively realizes the dynamic dispersion, intelligent regulation and systematic safety guarantee of prestress under karst geological conditions.

[0110] After completing the zoning tensioning control design of each functional section of the anchor cable and applying preliminary prestress, the project team continued to embed a high-frequency dynamic monitoring system based on FBG fiber optic strain gauges into each section of the anchor cable. By arranging fiber optic sensors in the core area of each section of the anchor cable, the team continuously collected data on the strain changes of each section of the anchor cable over time at a frequency of 10 Hz per second. The monitoring system grasps the dynamic process of prestress diffusion in real time, and can quickly determine whether the force of each section is uniform and synchronous, and promptly identify the existence of abnormal concentrated force sections or lagging sections that do not effectively participate in the force. During the monitoring and analysis phase, the project team defined the cumulative response value R of the force change of each section of the anchor cable according to the method set by the present invention. i , to comprehensively reflect the overall stress evolution characteristics of the anchor cable from the beginning of tensioning to any moment, the response quantity R i The mathematical expression is:

[0111]

[0112] where R i is the cumulative response value of the force change of the i-th anchor cable, ε i(t) is the instantaneous strain value of the segment at time t, is the strain growth rate of the anchor cable section, Φ(·) is the nonlinear response characteristic function, and in this project Φ is specifically taken as:

[0113]

[0114] Among them, η1 and η2 are the rate response weight and strain response weight, respectively, with a value range of η1 = 0.5 ~ 1.0 and η2 = 1.0 ~ 2.0, while the exponential coefficients ξ1 and ξ2 are used to adjust the sensitivity of different influencing factors, with a value range of ξ1 = 0.8 ~ 1.2 and ξ2 = 1.0 ~ 1.5, respectively.

[0115] During the monitoring process, taking the third anchor cable on the left side of the tunnel vault as an example, the tensioning start time of this section is t0 = 0 minutes, and the current analysis time point is 60 minutes after the tensioning starts. The monitoring record data shows that the instantaneous strain curve in the first 60 minutes is as follows. The strain growth rate is relatively fast at the beginning, and the average strain in the first 15 minutes is 0. It then slowed down to 0.0020με / s, and the total strain change increased from the initial 0με to 325με. During the calculation process, the project team took η1=0.8, η2=1.5, ξ1=1.0, ξ2=1.2 and substituted them into the function formula, and obtained the single-point response contribution at any time t:

[0116]

[0117] Take the monitoring value at the representative time t = 30 minutes, ε3(30)=200με, then the single point response contribution is:

[0118] Φ=0.8×0.0030+1.5×200 1.2 =0.0024+1.5×627.02=0.0024+940.53=940.5324

[0119] In the actual integration process, the monitoring data is discretized into a set of data per minute, and the numerical integral summation approximates the continuous integration. Finally, the cumulative summation in the 0-60 minute interval is obtained:

[0120]

[0121] Where Δt = 60 seconds, and each data update cycle corresponds to 1 minute. The final calculated cumulative response of the force change of the third section of the anchor cable is R3≈56320 (standardized unit). By comparing with other sections, it is found that the R3 value of this section is significantly higher than that of the first section (R1≈40100) and the fourth section (R4≈38700), indicating that there is a stress concentration trend in the third section. It is necessary to appropriately reduce the tensioning rate of this section in the subsequent tensioning and implement a local release operation to prevent local damage or shear instability of the anchor cable due to stress advance.

[0122] In the subsequent tensioning rhythm adjustment, the project team adjusted the i Feedback curve, the tensioning rate of the third section was reduced from the original setting of 1.5mm / min to 1.0mm / min, and the tensioning was suspended for 15 minutes, waiting for the other sections to follow the force synchronously. The results showed that after the tensioning rhythm was optimized, the R i The value deviation decreased by 35%, and the overall force balance of the anchor cable system was significantly improved during the tensioning process. Ultimately, no strain jump or breakage occurred in any section during the monitoring period, and the construction efficiency was improved by about 12%.

[0123] After the cumulative force response R of each anchor section i After real-time monitoring and preliminary slow-release adjustment, the project team further formally launched the dynamic tension rhythm optimization and control mechanism based on the method of the present invention, and through real-time monitoring of the R i (t) and the overall tensioning process synchronization offset η i (t), accurately and dynamically adjust the actual tensioning rate v of each anchor cable i (t) to ensure that the force of all functional segments is coordinated and consistent. The specific control relationship is as follows:

[0124]

[0125] where v i (t) is the actual tensioning rate of the i-th segment at time t, in mm / min, R i (t) is the current cumulative force response value of the segment, η i (t) is the synchronization offset between the segment and the overall average tensioning process, and the unit is minute difference. ζ1 and ζ2 are the weight coefficients of force response and synchronization adjustment, respectively. In this project, ζ1 is set between 2.0 and 5.0, and ζ2 is set between 1.0 and 3.0, so as to take into account both force growth and synchronization coordination. λ1 is the force response rate sensitivity parameter, and the value range is 0.00005 to 0.0002. The control index suppression item has a great influence on the high R i The value is the rate suppression strength of the paragraph, and λ2 is the synchronization adjustment sensitivity parameter, which ranges from 0.2 to 1.0 and is used to adjust the rate compensation rhythm of the asynchronous paragraph.

[0126] Taking an actual example, for the third anchor cable on the left side of the arch, at the 60th minute, the measured R3(60)=56320 is consistent with the average cumulative response R avg =45700, which is 23% higher than that of the previous one. Meanwhile, the synchronization offset η3(60) = +5 minutes, which is 5 minutes faster than the overall average tensioning progress. The project team used parameters ζ1 = 4.0, ζ2 = 2.0, λ1 = 0.0001, and λ2 = 0.5 for calculation. First, the exponential suppression term was obtained:

[0127]

[0128] Therefore, the contribution of the force response of the third segment is:

[0129] ζ1·(1-0.0036)=4.0×0.9964=3.9856

[0130] Secondly, the synchronization adjustment items are:

[0131] sin(λ2η3)=sin(0.5×5)=sin(2.5°)≈0.0436

[0132] The synchronization compensation part is:

[0133] ζ2·0.0436=2.0×0.0436=0.0872

[0134] Combining the two parts, the tensioning rate of the third section is:

[0135] v3(60)=3.9856+0.0872=4.0728mm / min

[0136] However, considering that the maximum tensioning rate allowed by the actual tensioning machinery and equipment at the construction site is set to 3mm / min, an upper limit protection is finally adopted for the rate of the third section, and the actual tensioning rate is controlled at 3mm / min. At the same time, combined with the stress concentration risk identified in the early stage, the on-site operators synchronously implement the tensioning-stagnation-slow release alternating rhythm, that is, continuous tensioning for 10 minutes and then pause for 5 minutes to ensure that the local stress gradually diffuses evenly.

[0137] At the same time, compared with the first section of anchor cable, at the 60th minute R1(60)=40100, which is lower than the average value R avg , and the synchronization offset η1(60) = -3 minutes, that is, the overall process is delayed by 3 minutes. Substituting the same parameters into the calculation, we get:

[0138]

[0139] ζ1·(1-0.0181)=4.0×0.9819=3.9276

[0140] sin(λ2η1)=sin(0.5×(-3))=sin(-1.5°)≈-0.0262

[0141] ζ2·(-0.0262)=2.0×(-0.0262)=-0.0524

[0142] v1(60)=3.9276-0.0524=3.8752mm / min

[0143] Due to the lag, the tensioning rate of the first section of anchor cable was appropriately accelerated to about 3.88mm / min to help it quickly keep up with the overall progress. After the tensioning rhythm was optimized and adjusted, the force growth curves of all functional sections gradually tended to be synchronized, the overall tensioning cycle was shortened by 8%, and the final cumulative force difference of each section of the anchoring system was within 5%, which was a significant improvement compared to the 12% force deviation before optimization, ensuring the force uniformity, prestress dispersion and overall structural safety of the tunnel structure under complex karst geological conditions.

[0144] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A design method for pressure-dispersed prestressed anchor cables in karst geology, characterized in that The following steps are involved: S1. Dynamic identification of prestress action path: S1.

1. Using geological 3D reconstruction combined with CT scanning and high-frequency radar imaging, we extract the path obstacle map composed of karst channels, cavities, and fracture zones; S1.

2. Apply graph neural networks to identify mechanical continuity paths: Identify spatial points where prestress transfer predictions may be cut off, bend, or leak; map these points to stress risk nodes, which serve as input for subsequent anchor cable structure variation and tensioning logic adjustments. S2, using pressure anisotropic response regulation mechanism: S2.

1. Implant a biaxial anisotropic elastic modulus material comprising a fiber composite cladding and a polymer elastic cavity in the anchor cable segment; S2.

2. Design a specific reverse deformation structure. When encountering a cavity or fracture zone in a certain direction, the anchor cable will undergo local pre-buckling / buffering deformation, actively guiding the stress to be transferred to the higher load-bearing area; S3. Use a controllable load-bearing closure mechanism in the cavity spanning section: S3.

1. Introduce an expandable closed structure, including an intelligent foam core / micro-pressure tension bladder, in the section where the anchor cable passes through the cavity. Arrange the structure to inherit pressure and stabilize the space: after expansion, the structure adheres to the cavity boundary, absorbs surrounding deformation, and forms a local force field. S3.2, the closed structure has embedded stress damping devices to buffer the tension fluctuations of adjacent sections; S4, tension and release coordinated control algorithm and segment-level active feedback strategy: S4.

1. Prestressed anchor cables are equipped with multiple tensioning ports or tension adjustment segments, each segment being managed by an independent controller and sensor; S4.

2. Based on real-time stress feedback including FBG fiber optic strain gauges, determine which sections experience stress concentration and which sections are not subject to stress; The tensioning rate, sequence and even pause / release are dynamically adjusted according to force feedback to form the main / auxiliary tensioning rhythm.

2. A method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 1, characterized in that The dynamic identification method of the prestressing action path: CT scan images are collected to obtain data on density changes within the rock mass, reflecting porosity, cavity boundaries, and overall material strength attenuation. High-frequency geological radar (GPR) is also used to detect electromagnetic reflectivity to identify potential discontinuous interfaces, fracture zones, and hidden dissolution structures. These two signals, representing material solidity and interface reflectivity, respectively, are mapped to a unified geological integrity index by constructing a fusion algorithm.

3. The method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 2 is characterized in that The dynamic identification method of the prestressing action path: In the reconstructed 3D model, the connection paths between each unit need to be evaluated for mechanical connectivity. That is, during the actual tensioning process, whether the prestress is transferred from the anchor segment through the region to another segment. The 3D grid structure is abstracted into a graph structure G = (N, E), where the node N represents the spatial unit and the edge E represents the potential stress path. The following weights are defined: in: Ω mn is the feasibility weight of prestress transfer between node m and node n; μ m ,μ n Score the mechanical integrity of nodes m and n respectively; is the coordinate vector of nodes m and n in three-dimensional space; is the spatial distance between two nodes; Θ is the penalty function for path direction change. When the path curvature exceeds the set threshold Δ, an additional penalty is given, indicating that the continuity of path force transmission decreases. κ is the penalty coefficient, which is used to adjust the impact of path direction deviation on the overall weight. By calculating Ω for each pair of adjacent units mn , construct a complete mechanical feasible path map; in the subsequent tensioning, the stress is preferentially along the high Ω mn The path diffusion, while low Ω mn There is a risk of power transmission interruption or leakage in the area.

4. The method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 3 is characterized in that The dynamic identification method of the prestressing action path: Cluster analysis is performed on the spatial clustering of the paths. If multiple failure paths appear in a certain spatial area, the area is determined to be a potential anchor failure area, i.e., a stress risk node set. Define the spatial risk response function As shown below: in: Any point in three-dimensional space Local stress risk responsiveness; S is the set of all identified high-risk nodes; is the spatial location of the risk node; For nodes The risk weight reflects the degree of local fracture or force transmission risk; is a three-dimensional pulse function, only The value is 1 when the risk is high, and 0 otherwise, which is used to express the local risk focusing effect.

5. The method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 4 is characterized in that By calculating the position of each Draw a risk density distribution map. When the risk response of a certain area is higher than the set threshold χ0, make the following design adjustments: P1. This section of anchor cable adopts flexible buffer section; P2, adjust the tensioning time and force rate of the section; P3, enter the cavity relay structure or secondary anchor point.

6. The method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 1 is characterized in that The tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include: During the anchor cable structure design stage, a segmented controllable force application strategy is adopted to divide the anchor cable into several functional sections. Each section is independently equipped with a tensioning port and an adjustable force application mechanism, so that each section has the ability to independently regulate prestressed loading; the prestressing level of each section is dynamically allocated according to the geological environment and structural requirements.

7. A method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 6, characterized in that The tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include: A high-frequency dynamic monitoring system based on FBG fiber optic strain gauges is embedded in each functional segment. By collecting real-time data on the strain changes of each segment of the anchor cable over time, the system can understand the progress of prestress diffusion, determine whether the force transmission is uniform, and identify abnormally concentrated or non-stressed segments.

8. The method for designing a pressure-distributed prestressed anchor cable in karst geology according to claim 7 is characterized in that The tension and release coordinated control algorithm and the segment-level active feedback strategy construction method include: Adopt dynamic tensioning rhythm optimization and control mechanism; in tensioning operation, according to the cumulative force response R of each segment i and the overall tensioning process offset η i (t), real-time adjustment of the tensioning rate v of each segment i (t) to coordinate the force pace of each section; the dynamic control relationship of tensioning rate is defined as follows: in: v i (t) is the actual tension rate of the i-th functional unit at time t; R i (t) is the cumulative force response value of the segment at the current moment; η i (t) is the synchronization offset of the i-th segment relative to the overall tensioning process; Ψ(·) is the tensioning rhythm control function, which comprehensively controls the tensioning rate of each segment; ζ1,ζ2 are the force response and synchronization adjustment weight coefficients respectively; λ1,λ2 are the force response rate sensitivity adjustment parameters and synchronization period adjustment parameters respectively; is an exponential inhibition term, which controls the tension rate of the section with too fast a force increase; sin(λ2η i (t)) is a periodic sinusoidal adjustment term used to balance the synchronization between different segments.

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