An artificial false roof safety evaluation method and system based on cumulative damage inversion
Patent Information
- Application Number
- CN202610982455.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-02
- Publication Date
- 2026-10-16
AI Technical Summary
（1）现有技术往往假设假顶初始状态为无损弹塑性体，导致计算出的安全系数偏大，存在安全隐患
[0022] This invention provides a method and system for safety evaluation of artificial false roofs based on cumulative damage inversion. By constructing a wave impedance coupling model to invert the stiffness degradation degree and cumulative damage variables of the filling body throughout its entire life cycle, and combining the corrected ultimate tensile strain with real-time dynamic and static superimposed strain to establish a time-varying safety factor calculation, the safety status assessment and graded early warning of the artificial false roof during the exposure and bearing process are realized, thereby significantly improving the safety of mining operations and alleviating the technical problem of inaccurate safety factor calculation leading to safety hazards in existing technologies.
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Figure CN122919461A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of artificial false roof safety assessment technology, and in particular to an artificial false roof safety assessment method and system based on cumulative damage inversion. Background Technology
[0002] As mineral resource mining extends to deeper and more complex ore bodies, the down-pass backfill mining method has become widely used in the mining of high-grade, fractured, and difficult-to-mine bodies due to its advantages such as high mining safety, high resource recovery rate, and minimal disturbance to the surface environment. The core technical feature of this mining method is that after mining the upper pass, an artificial false roof is formed through backfilling, and then the lower pass mining operation is carried out using this artificial false roof as a supporting structure. In actual mining operations, the artificial false roof not only needs to support the weight of the overlying backfill but also needs to withstand the frequent vibrations generated by the blasting operations in this layer of tunneling. Therefore, the stability of the artificial false roof directly determines the operational safety of the lower pass mining process and is a key element in ensuring the continuous and efficient advancement of the entire mining process.
[0003] Currently, the evaluation of the stability of artificial false ceilings in down-path routes mainly relies on the following two approaches: (1) Using the theory of simply supported beams, thin plates or thick plates, combined with the strength parameters of the filling body measured by indoor tests, calculate the ultimate span or safety factor of the false roof; (2) Pre-embed multiple displacement gauges or earth pressure cells inside the filling body to monitor the settlement or internal stress changes of the false roof during the exposure process, and issue an early warning when the monitored value exceeds the preset threshold.
[0004] However, existing technologies typically only focus on the stress state of the artificial false roof during the exposed bearing stage. In reality, the backfill material has already undergone multiple rounds of blasting vibrations before it is exposed as a false roof (i.e., during the previous layer's mining or the current layer's tunneling). These early dynamic loads can cause microcracks to initiate inside the backfill material, resulting in irreversible cumulative damage and deterioration of its mechanical properties before it officially bears load. Existing technologies have the following problems: (1) Existing technologies often assume that the initial state of the false ceiling is a non-destructive elastoplastic body, which leads to an overestimation of the safety factor and potential safety hazards.
[0005] (2) Current monitoring methods can only reflect the current macroscopic deformation results and it is difficult to distinguish whether the deformation is caused by an increase in external load or by a decrease in the stiffness of the material itself.
[0006] (3) Most existing evaluation methods are static, that is, they only consider the self-weight of the overburden. However, in actual downhole conditions, the false roof often becomes unstable due to blasting disturbance when the static load is high.
[0007] (4) Existing safety factor calculation methods fail to cover this time-varying characteristic and cannot achieve accurate early warning of dynamic risks throughout the entire life cycle. Summary of the Invention
[0008] To address the aforementioned technical problems in the existing technology, embodiments of the present invention provide a method and system for safety assessment of artificial false ceilings based on cumulative damage inversion. The technical solution is as follows: On the one hand, a method for safety evaluation of artificial false roofs based on cumulative damage inversion is provided. The method includes: arranging multiple monitoring sections at intervals along the extension direction of the target artificial false roof, and setting strain sensors at monitoring point positions on each monitoring section; the target artificial false roof is a downward-facing artificial false roof; determining the occurrence state of the monitoring points on the target artificial false roof based on the positional relationship between the longwall face and each monitoring section; the occurrence state includes a dynamic load damage accumulation stage and an exposure bearing stage; determining the monitoring points in the exposure bearing stage as the evaluation points, and calculating each blasting operation on the longwall face based on the blasting vibration parameters of the mine where the target artificial false roof is located. The theoretical dynamic strain generated at the measurement point to be evaluated is calculated; based on the peak value of the measured dynamic tensile strain generated at the measurement point by each blast on the longwall face collected by the strain sensor, the stiffness degradation ratio of a single blast is calculated based on the theoretical dynamic strain and the peak value of the measured dynamic tensile strain; based on the stiffness degradation ratio, the cumulative damage variable generated at the measurement point to be evaluated by multiple blasts on the longwall face is calculated, and the dynamic safety factor of the measurement point to be evaluated is constructed based on the cumulative damage variable; the minimum value of the dynamic safety factor at the measurement point to be evaluated is used as the evaluation index of the target artificial roof, and the safety evaluation of the target artificial roof is performed based on the evaluation index.
[0009] Optionally, multiple monitoring sections are arranged at intervals along the extension direction of the target artificial roof, and strain sensors are installed at monitoring points on each monitoring section. This includes: arranging multiple monitoring sections at equal intervals along the extension direction of the target artificial roof; wherein the spacing between adjacent monitoring sections is an integer multiple of the blasting cycle advance; setting a monitoring point at the bottom of the geometric center of each monitoring section, and embedding a strain sensor at the monitoring point; the strain sensor includes a concrete strain gauge.
[0010] Optionally, the method further includes: constructing a three-dimensional local coordinate system with the center of the entrance floor of the current mining route as the origin, the tunneling extension direction as the X-axis, the width direction of the route as the Y-axis, and the vertical upward direction as the Z-axis.
[0011] Optionally, based on the positional relationship between the longwall face and each monitoring section, the existence status of the monitoring points on the target artificial roof is determined, including: if the X-axis coordinate of the longwall face is less than the X-axis coordinate of the i-th monitoring section, the existence status of the monitoring points on the i-th monitoring section is determined as the dynamic damage accumulation stage; if the X-axis coordinate of the longwall face is greater than or equal to the X-axis coordinate of the i-th monitoring section, the existence status of the monitoring points on the i-th monitoring section is determined as the exposed bearing stage.
[0012] Optionally, the blasting vibration parameters include the medium coefficient K and the attenuation index. Elastic longitudinal wave velocity of the filling material under undamaged conditions The theoretical formula for calculating dynamic strain includes:
[0013] In the formula, Let Q be the theoretical dynamic strain, Q be the maximum single-stage detonation charge, and R be the distance from the detonation center to the measurement point to be evaluated. The velocity of the particle is denoted as .
[0014] Optionally, the formula for calculating the stiffness degradation ratio includes:
[0015] In the formula, The stiffness degradation ratio is mentioned above. The measured peak value of dynamic tensile strain is... The theoretical dynamic strain is given.
[0016] Optionally, the formula for calculating the cumulative damage variable includes:
[0017] In the formula, Let be the cumulative damage variable at time t. The cumulative number of blasts applied to the measurement point to be evaluated up to time t, where k is the blast number sequence number. This is the damage impact coefficient; The formula for calculating the dynamic safety factor includes:
[0018] In the formula, The dynamic safety factor is... To correct the ultimate tensile strain on site, The ultimate tensile strain of the standard specimen filled with filler, measured in the laboratory. This is the static evolution term of the strain data acquired by the strain sensor.
[0019] Optionally, the security evaluation of the target artificial dome based on the evaluation index includes: if the evaluation index is greater than a first preset threshold, then the target artificial dome is determined to be of a first security level; if the evaluation index is less than or equal to the first preset threshold and greater than a second preset threshold, then the target artificial dome is determined to be of a second security level; if the evaluation index is less than or equal to the second preset threshold, then the target artificial dome is determined to be of a third security level.
[0020] Optionally, the method further includes a graded early warning system, which includes: if the target artificial false roof is at the first safety level, no manual intervention is performed; if the target artificial false roof is at the second safety level, the sampling frequency of the strain sensor is increased, manual inspection is carried out, and the maximum amount of detonating explosive in a single section is reduced; if the target artificial false roof is at the third safety level, the operation is stopped.
[0021] On the other hand, a safety evaluation system for artificial false roofs based on cumulative damage inversion is also provided to implement the safety evaluation method for artificial false roofs based on cumulative damage inversion provided in the embodiments of the present invention. The system includes: a deployment module, a determination module, a first calculation module, a second calculation module, a construction module, and an evaluation module. The deployment module is used to deploy multiple monitoring sections at intervals along the extension direction of the target artificial false roof, and to set strain sensors at monitoring point positions on each monitoring section. The target artificial false roof is a downward-facing artificial false roof. The determination module is used to determine the state of the monitoring points on the target artificial false roof based on the positional relationship between the longwall face and each monitoring section. The state includes a dynamic load damage accumulation stage and an exposure bearing stage. The first calculation module is used to determine the monitoring points in the exposure bearing stage as the evaluation points, and based on the... The first module calculates the theoretical dynamic strain generated by each blast on the mining face at the target artificial roof based on the blasting vibration parameters of the mine where the target artificial roof is located. The second module calculates the stiffness degradation ratio of a single blast based on the measured peak dynamic tensile strain generated by each blast on the mining face at the target artificial roof, collected by the strain sensor. The third module calculates the cumulative damage variable generated by multiple blasts on the mining face at the target artificial roof based on the stiffness degradation ratio, and constructs the dynamic safety factor of the target artificial roof based on the cumulative damage variable. The fourth module evaluates the target artificial roof by using the minimum dynamic safety factor of the target artificial roof as the evaluation index, and performs a safety evaluation based on the evaluation index.
[0022] This invention provides a method and system for safety evaluation of artificial false roofs based on cumulative damage inversion. By constructing a wave impedance coupling model to invert the stiffness degradation degree and cumulative damage variables of the filling body throughout its entire life cycle, and combining the corrected ultimate tensile strain with real-time dynamic and static superimposed strain to establish a time-varying safety factor calculation, the safety status assessment and graded early warning of the artificial false roof during the exposure and bearing process are realized, thereby significantly improving the safety of mining operations and alleviating the technical problem of inaccurate safety factor calculation leading to safety hazards in existing technologies. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a flowchart of a method for assessing the safety of artificial false roofs based on cumulative damage inversion, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a strain sensor layout according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the technical route of an artificial false ceiling safety evaluation method based on cumulative damage inversion provided by an embodiment of the present invention; Figure 4 This is a schematic diagram of an artificial false ceiling safety evaluation system based on cumulative damage inversion provided in an embodiment of the present invention. Detailed Implementation
[0025] The technical solution of the present invention will now be described with reference to the accompanying drawings.
[0026] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.
[0027] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.
[0028] Figure 1 This is a flowchart of a method for assessing the safety of artificial false roofs based on cumulative damage inversion, according to an embodiment of the present invention. Figure 1 As shown, the method specifically includes the following steps: Step S102: Multiple monitoring sections are set up at intervals along the extension direction of the target artificial roof, and strain sensors are set at the monitoring point positions on each monitoring section; the target artificial roof is a downward-facing artificial roof.
[0029] Step S104: Based on the positional relationship between the longwall face and each monitoring section, determine the existence status of the monitoring points on the target artificial roof; the existence status includes the dynamic load damage accumulation stage and the exposed bearing stage.
[0030] Step S106: The monitoring points in the exposed bearing stage are identified as the measurement points to be evaluated, and the theoretical dynamic strain generated by each blast on the longwall face is calculated based on the blasting vibration parameters of the mine where the target artificial false roof is located.
[0031] Step S108: Based on the peak value of the measured dynamic tensile strain generated by each blast on the mining face by the strain sensor, the stiffness degradation ratio of a single blast is calculated based on the theoretical dynamic strain and the peak value of the measured dynamic tensile strain.
[0032] Step S110: Based on the stiffness degradation ratio, calculate the cumulative damage variable generated by multiple blasts on the longwall face to be evaluated at the test point, and construct the dynamic safety factor of the test point to be evaluated based on the cumulative damage variable.
[0033] Step S112: The minimum dynamic safety factor of the measurement points to be evaluated is used as the evaluation index of the target artificial false roof, and the safety evaluation of the target artificial false roof is carried out based on the evaluation index.
[0034] Specifically, prior to step S102, the method provided in this embodiment of the invention further includes: taking the center of the entrance bottom plate of the current mining route as the origin. A three-dimensional local coordinate system is constructed with the tunneling extension direction as the X-axis, the tunnel width direction as the Y-axis, and the vertical upward direction as the Z-axis. This coordinate system can describe the advancing position of the longwall face. Spatial geometric relationship with the location of the monitoring point.
[0035] Specifically, step S102 further includes the following steps: Step S1021: Multiple monitoring sections are evenly spaced along the extension direction of the target artificial false roof; wherein the spacing between adjacent monitoring sections is an integer multiple of the blasting cycle advance. Step S1022: Set a monitoring point at the bottom of the geometric center of each monitoring section, and embed a strain sensor at the monitoring point location; the strain sensor includes a concrete strain gauge.
[0036] Figure 2This is a schematic diagram illustrating the arrangement of a strain sensor according to an embodiment of the present invention. Figure 2 As shown, for a path of length L and width W, the spacing is calculated along the X-axis. Set up N monitoring sections, The value should be an integer multiple of the blasting cycle advance, for example, 12~15m; the X coordinate of the i-th monitoring section is... .
[0037] Considering that the artificial roof of the downward-entry filling body mainly exhibits the stress characteristics of a simply supported beam or a thick plate, its maximum bending tensile stress usually occurs in the central region at the bottom of the section. Therefore, at the geometric center bottom of the i-th monitoring section (coordinate: High-precision concrete strain gauges were installed. Among them, This is the elevation of the approach road's base plate; The protective layer thickness is typically around 200mm to prevent damage to the sensor during the lower approach mining process. This sensor can collect axial strain data inside the filling body around the clock. .
[0038] Specifically, step S104 includes: If the X-axis coordinate of the longwall face is less than the X-axis coordinate of the i-th monitoring section, then the storage status of the monitoring point on the i-th monitoring section is determined as the dynamic damage accumulation stage. If the X-axis coordinate of the longwall face is greater than or equal to the X-axis coordinate of the i-th monitoring section, then the state of the monitoring point on the i-th monitoring section is determined as the exposed bearing stage.
[0039] Specifically, this invention updates the X-coordinate of the longwall face daily according to the mining plan and actual operations. According to the location of the longwall face Location of monitoring points The relationship divides the artificial false top assignment state into two stages: (1) Dynamic damage accumulation stage ( ): Since the monitoring point is located within the unexposed backfill and is constrained by the surrounding rock or backfill, a safety assessment of the artificial false roof is not conducted at this stage. As the tunnel is excavated, the damage caused by blasting vibrations accumulates, leading to the initiation and propagation of microcracks within the backfill, resulting in the deterioration of the mechanical properties of the backfill.
[0040] (2) Exposure bearing stage ): Once the working face passes the monitoring point, the infill at that point loses the support of the surrounding rock at the bottom and transforms into an artificial false roof structure, which is then exposed. At this point, the artificial false roof is simultaneously subjected to the deterioration of mechanical properties due to cumulative damage and the static tension caused by the overlying load. This is a high-risk period for accidents such as delamination and collapse of the artificial false roof, and a safety assessment of the artificial false roof is required at this stage.
[0041] Figure 3 This is a schematic diagram of the technical route for a safety assessment method for artificial false roofs based on cumulative damage inversion according to an embodiment of the present invention. Figure 3 As shown, the cumulative damage inversion process provided in this embodiment of the invention is as follows: (1) Obtaining the vibration parameters of basic blasting in the mine: The blasting vibration parameters of the mine where the target artificial roof is located are obtained in advance through blasting vibration testing, including the medium coefficient K and the attenuation index. And the elastic longitudinal wave velocity of the filling material in a damage-free state. .
[0042] (2) Calculate the theoretical dynamic strain of a single blast: Each time a blast is performed at the longwall face (maximum single-stage explosive charge is Q, distance from the blast center to the measurement point to be evaluated is R), according to the Sadovsky formula, the particle vibration velocity is... proportional distance The particle vibration velocity decays as a power function, and the formula for calculating the velocity is:
[0043] Under the far-field elastic wave assumption, the dynamic strain within the medium With particle vibration velocity They are directly proportional, that is:
[0044] Therefore, theoretical dynamic strain Similarly, it follows the same principle as the vibration velocity of the particle. The decay law of isomorphic power functions.
[0045] (3) Define the single-step damage factor based on stiffness degradation: When the artificial roof is undamaged, the measured strain value closely matches the theoretical strain value. However, if the filling material suffers internal damage due to blasting vibration, its equivalent stiffness will decrease, resulting in tensile deformation greater than the theoretical strain value under the same vibration energy. The peak dynamic tensile strain value measured by the strain sensor at the instant of the blast is extracted. Define the stiffness degradation ratio of a single blast. :
[0046] like This indicates that the measured strain is consistent with the theoretical no-damage strain, and that the filling material shows no stiffness deterioration and no new damage; if This indicates that the measured strain is greater than the theoretical strain, the stiffness of the filling material decreases, and new damage exists. The larger the value, the more significant the stiffness degradation. (4) Cumulative damage variables Iterative updates: Since damage is an irreversible cumulative process, we define the cumulative damage variable at time t. The value range is 0~1:
[0047] like This indicates that the material is in an ideal elastic state and there is no new damage; if This indicates that the material stiffness has degraded, resulting in plastic damage.
[0048] in The cumulative number of blasts applied to the monitoring point to be evaluated up to time t; k is the blast number sequence number. This corresponds to a single explosion event; The damage impact coefficient, The contribution weight of the stiffness degradation factor to damage accumulation is used to correct the stiffness degradation factor, and it needs to be calibrated through field tests.
[0049] Throughout the entire lifecycle of the artificial false roof, damage calculations are performed for every blasting operation near the monitoring route (including blasting of this route and surrounding routes). It accumulates and updates with each explosion.
[0050] Specifically, such as Figure 3 As shown, the calculation process of the time-varying dynamic safety factor for dynamic-static coupling drive in this embodiment of the invention is as follows: (1) Considering the residual strength threshold of cumulative damage: Based on the principles of damage mechanics of filling materials, blasting vibrations continuously reduce the material's elastic modulus, tensile strength, and ultimate tensile strain. Therefore, the in-situ corrected ultimate tensile strain at time t is defined. :
[0051] In the formula, The ultimate tensile strain of the standard specimen filled with filler, measured in the laboratory.
[0052] (2) Constructing a dynamic safety factor : The strain sensor continuously acquires strain data inside the filling material at high frequency. For any time t, the signal is decomposed into static evolution terms using moving average filtering or wavelet decomposition techniques. and dynamic response items Among them, the static evolution term To filter out high-frequency noise and the trend term after transient impact, the dynamic response term characterizes the normal deformation of the infill under its own weight and overburden load. To extract the measured dynamic tensile strain peak value centered at the blast moment, and to characterize the elastic wave response of the filling body excited by the blast vibration.
[0053] Based on the in-situ corrected ultimate tensile strain, a time-varying safety factor is constructed. Computational model:
[0054] If there is an explosion at the current moment, then The peak dynamic strain of the blast is included; if there is no blast, this item is 0. In this embodiment of the invention, the dynamic safety factor can simultaneously capture the risks of long-term creep and sudden dynamic load instability.
[0055] Specifically, step S112, which involves conducting a safety assessment of the target artificial dome based on evaluation metrics, includes: If the evaluation index is greater than the first preset threshold, the target artificial false ceiling is determined to be of the first safety level; If the evaluation index is less than or equal to the first preset threshold and greater than the second preset threshold, then the target artificial false ceiling is determined to be of the second safety level. If the evaluation index is less than or equal to the second preset threshold, the target artificial false ceiling is determined to be at the third safety level.
[0056] Preferably, the method provided in this embodiment of the invention further includes tiered early warning, wherein the tiered early warning includes: If the target artificial false ceiling is at the first safety level, no manual intervention will be performed; If the target artificial false ceiling is at the second safety level, increase the sampling frequency of the strain sensor, conduct manual inspections, and reduce the maximum amount of detonating explosive per section. If the target artificial ceiling is at the third safety level, then operations should be stopped.
[0057] Specifically, such as Figure 3 As shown, this embodiment of the invention also provides an artificial pseudo-peak multidimensional state assessment and hierarchical early warning mechanism, specifically including: This invention uses a route as a unit and calculates the dynamic safety factor from all N monitoring points within that route in real time. and take its minimum value. This serves as an evaluation index for the overall stability of the artificial false ceiling in the current approach. It is combined with the cumulative damage variable calculated in previous steps. The artificial false ceiling is divided into three safety levels, and corresponding hierarchical control strategies are implemented.
[0058] (1) Green status (i.e., first safety level) ): Status description: The first safety reserve factor (i.e., the first preset threshold) is recommended to be 2.0 to 2.5; at this point, the artificial false ceiling is in the elastic deformation stage, accumulating damage. The strength of the filling material is much higher than the combined effect of the current static and dynamic loads.
[0059] Control measures: The system maintains a normal data collection and storage mode without manual intervention, and regularly generates weekly reports on the security status of the false top.
[0060] (2) Yellow status (i.e., second security level) ): Status description: The critical warning coefficient (i.e., the second preset threshold) is recommended to be between 1.5 and 2.0; at this point, the artificial false roof has accumulated damage in a localized area due to multiple historical blasts. The mechanical parameters of the artificial false roof have deteriorated significantly due to the increased load. Although there is no immediate risk of collapse, the structure's sensitivity to dynamic loads has increased significantly, and its resistance to disturbances has decreased.
[0061] Control measures: The system increases the sampling frequency to capture the waveform characteristics of the blasting moment more precisely; the frequency of on-site inspections of the artificial roof by technical personnel is increased to check for cracks in the artificial roof, and the maximum amount of explosive charge per segment for blasting in this or nearby routes is reduced to slow down the damage rate.
[0062] (3) Red status (i.e., third security level) ): State Description: At this point, the safety margin of the artificial roof is extremely low. The combined dynamic and static loads on the artificial roof are approaching its ultimate strength. The artificial roof structure may be in an accelerated rheological stage or is about to fracture. Control measures: The system immediately triggers the downhole audible and visual alarm; all operations in the area are forcibly stopped, personnel and equipment are evacuated, and after the surrounding rock stabilizes, steel arches are erected for passive reinforcement according to the dangerous coordinate area indicated by the system until the monitoring data returns to the convergence range.
[0063] As described above, the embodiments of the present invention provide a safety evaluation method for artificial false roofs based on cumulative damage inversion. By constructing a wave impedance coupling model to invert the stiffness degradation degree and cumulative damage variables of the filling body throughout its entire life cycle, and combining the corrected ultimate tensile strain with the real-time dynamic and static superimposed strain to establish a time-varying safety factor calculation, the safety status assessment and graded early warning of the artificial false roof during the exposure and bearing process can be realized, thereby significantly improving the safety of mining operations.
[0064] Figure 4 This is a schematic diagram of an artificial false ceiling safety assessment system based on cumulative damage inversion according to an embodiment of the present invention. Figure 4 As shown, the system includes: a deployment module 10, a determination module 20, a first calculation module 30, a second calculation module 40, a construction module 50, and an evaluation module 60.
[0065] Specifically, the deployment module 10 is used to deploy multiple monitoring sections at intervals along the extension direction of the target artificial roof, and to set strain sensors at the monitoring point positions on each monitoring section; the target artificial roof is a downward-facing artificial roof. The determination module 20 is used to determine the existence status of the monitoring points on the target artificial roof based on the positional relationship between the longwall face and each monitoring section; the existence status includes the dynamic load damage accumulation stage and the exposed bearing stage; The first calculation module 30 is used to identify the monitoring points in the exposed bearing stage as the measurement points to be evaluated, and to calculate the theoretical dynamic strain generated by each blast on the longwall face of the measurement points to be evaluated based on the blasting vibration parameters of the mine where the target artificial false roof is located. The second calculation module 40 is used to calculate the stiffness degradation ratio of a single blast based on the measured peak value of dynamic tensile strain generated at the test point to be evaluated by each blast on the mining face, based on the theoretical dynamic strain and the measured peak value of dynamic tensile strain. Module 50 is used to calculate the cumulative damage variable of the test point to be evaluated caused by multiple blasts on the longwall face based on the stiffness deterioration ratio, and to construct the dynamic safety factor of the test point to be evaluated based on the cumulative damage variable. Evaluation module 60 is used to take the minimum dynamic safety factor of the measurement points to be evaluated as the evaluation index of the target artificial false roof, and to conduct a safety evaluation of the target artificial false roof based on the evaluation index.
[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A safety assessment method for artificial false roofs based on cumulative damage inversion, characterized in that, The method includes: Multiple monitoring sections are arranged at intervals along the extension direction of the approach road for the target artificial false roof, and strain sensors are installed at the monitoring point positions on each monitoring section; the target artificial false roof is a downward approach artificial false roof; Based on the positional relationship between the longwall face and each monitoring section, the existence status of the monitoring points on the target artificial roof is determined; the existence status includes the dynamic load damage accumulation stage and the exposed bearing stage; The monitoring points in the exposed bearing stage are identified as the measurement points to be evaluated, and the theoretical dynamic strain generated by each blast on the mining face is calculated based on the blasting vibration parameters of the mine where the target artificial false roof is located. The measured dynamic tensile strain peak value generated by each blast on the mining face is collected by the strain sensor and applied to the measurement point to be evaluated. The stiffness degradation ratio of a single blast is calculated based on the theoretical dynamic strain and the measured dynamic tensile strain peak value. Based on the stiffness degradation ratio, the cumulative damage variable caused by multiple blasts on the mining face to the measurement point to be evaluated is calculated, and the dynamic safety factor of the measurement point to be evaluated is constructed based on the cumulative damage variable. The minimum dynamic safety factor among the measurement points to be evaluated is used as the evaluation index of the target artificial roof, and the safety of the target artificial roof is evaluated based on the evaluation index.
2. The method according to claim 1, characterized in that, Multiple monitoring sections are spaced out along the route extension direction of the target artificial spur roof, and strain sensors are installed at monitoring points on each monitoring section, including: Multiple monitoring sections are evenly spaced along the extension direction of the artificial false roof of the target; the spacing between adjacent monitoring sections is an integer multiple of the blasting cycle advance. A monitoring point is set at the bottom of the geometric center of each monitoring section, and a strain sensor is embedded at the monitoring point; the strain sensor includes a concrete strain gauge.
3. The method according to claim 1, characterized in that, The method further includes: constructing a three-dimensional local coordinate system with the center of the entrance floor of the current mining route as the origin, the tunneling extension direction as the X-axis, the width direction of the route as the Y-axis, and the vertical upward direction as the Z-axis.
4. The method according to claim 3, characterized in that, Based on the positional relationship between the longwall face and each monitoring section, the status of the monitoring points on the target artificial roof is determined, including: If the X-axis coordinate of the longwall face is less than the X-axis coordinate of the i-th monitoring section, then the storage status of the monitoring point on the i-th monitoring section is determined as the dynamic damage accumulation stage. If the X-axis coordinate of the longwall face is greater than or equal to the X-axis coordinate of the i-th monitoring section, then the state of the monitoring point on the i-th monitoring section is determined as the exposed bearing stage.
5. The method according to claim 1, characterized in that, The blasting vibration parameters include the medium coefficient K and the attenuation index. Elastic longitudinal wave velocity of the filling material under undamaged conditions ; The formulas for calculating theoretical dynamic strain include: In the formula, Let Q be the theoretical dynamic strain, Q be the maximum single-stage detonation charge, and R be the distance from the detonation center to the measurement point to be evaluated. The velocity of the particle is denoted as .
6. The method according to claim 1, characterized in that, The formula for calculating the stiffness degradation ratio includes: In the formula, The stiffness degradation ratio is mentioned above. The measured peak value of dynamic tensile strain is... The theoretical dynamic strain is given.
7. The method according to claim 6, characterized in that, The formula for calculating the cumulative damage variable includes: In the formula, Let be the cumulative damage variable at time t. The number of blasts applied to the measurement point to be evaluated up to time t is the cumulative number of blasts, where k is the blast number sequence number. This is the damage impact coefficient; The formula for calculating the dynamic safety factor includes: In the formula, The dynamic safety factor is... To correct the ultimate tensile strain on site, The ultimate tensile strain of the standard specimen filled with filler, measured in the laboratory. This is the static evolution term of the strain data acquired by the strain sensor.
8. The method according to claim 1, characterized in that, A safety assessment of the target artificial dome is conducted based on the aforementioned evaluation indicators, including: If the evaluation index is greater than the first preset threshold, then the target artificial dome is determined to be of the first safety level; If the evaluation index is less than or equal to the first preset threshold and greater than the second preset threshold, then the target artificial false ceiling is determined to be at the second safety level. If the evaluation index is less than or equal to the second preset threshold, the target artificial dome is determined to be at the third safety level.
9. The method according to claim 8, characterized in that, The method further includes tiered early warning, wherein the tiered early warning includes: If the target artificial false ceiling is at the first security level, no manual intervention will be performed; If the target artificial false ceiling is at the second safety level, then increase the sampling frequency of the strain sensor, conduct manual inspections, and reduce the maximum amount of detonating explosive in a single section; If the target artificial ceiling is at the third safety level, then operations shall be stopped.
10. A safety assessment system for artificial false ceilings based on cumulative damage inversion, characterized in that, This system is used to implement the artificial false ceiling safety evaluation method based on cumulative damage inversion as described in any one of claims 1-9; the system comprises: a deployment module, a determination module, a first calculation module, a second calculation module, a construction module, and an evaluation module; wherein, The deployment module is used to deploy multiple monitoring sections at intervals along the extension direction of the target artificial roof, and to set strain sensors at monitoring point positions on each monitoring section; the target artificial roof is a downward-facing artificial roof. The determining module is used to determine the existence status of the monitoring points on the target artificial roof based on the positional relationship between the longwall face and each monitoring section; the existence status includes the dynamic load damage accumulation stage and the exposed bearing stage; The first calculation module is used to determine the monitoring point in the exposed bearing stage as the measurement point to be evaluated, and to calculate the theoretical dynamic strain generated by each blast on the longwall face on the measurement point to be evaluated based on the blasting vibration parameters of the mine where the target artificial false roof is located. The second calculation module is used to calculate the stiffness degradation ratio of a single blast based on the measured peak value of dynamic tensile strain generated by each blast on the mining face by the strain sensor. The construction module is used to calculate the cumulative damage variable of the multiple blasts carried out on the longwall face to the test point to be evaluated based on the stiffness deterioration ratio, and to construct the dynamic safety factor of the test point to be evaluated based on the cumulative damage variable. The evaluation module is used to take the minimum dynamic safety factor of the measurement point to be evaluated as the evaluation index of the target artificial false roof, and to conduct a safety evaluation of the target artificial false roof based on the evaluation index.