Premonition early warning analysis method based on subcritical state of rock-stress system
By identifying the subcritical state of the rock-stress system and building an intelligent identification model, the problem that the existing technology is difficult to identify and early warning of the transition state of rock from stability to instability is solved, and effective early warning and blocking of rock instability is achieved to prevent the occurrence of major instability disasters.
Patent Information
- Application Number
- CN202510074331.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-04-29
AI Technical Summary
The prior art is difficult to identify and early warning of the transition state of rocks from stability to instability, which makes it difficult to effectively block the further development to instability, thereby preventing the occurrence of major instability disasters.
By identifying the subcritical state of the rock-stress system, capturing the monitoring feature information of early warning feature point I and early warning feature point II, and building an intelligent identification model to achieve long-term forecast of rock instability and multi-level early warning of short-term early warning.
It can more easily and efficiently identify the subcritical state of rocks, provide effective early warning, and block further development towards instability, thereby preventing the occurrence of major instability disasters.
Smart Images
Figure CN119902304A_ABST
Abstract
Description
Technical Field
[0001] The invention provides a precursor warning analysis method based on the subcritical state of a rock-stress system, belonging to the technical field of geological monitoring. Background Art
[0002] The process of rock state change under external stress can be regarded as the process of rock developing from an initial steady state to another steady state. When the external stress level exceeds a certain strength of the rock, the rock slides from the initial steady state to the next steady state. Whether it is "initial steady state → another steady state" or "initial steady state → instability", the two states cannot be converted back and forth. The process has the basic characteristics of unidirectional and irreversible. Starting from the law of entropy increase, the rock under external stress is regarded as a narrow system, that is, a rock-stress system.
[0003] However, the subcritical state of rock is not simply the expansion of cracks, but also involves the weakening of rock mechanical properties and the transformation of fracture mechanisms. If the transition state from stability to instability can be identified and intervention is made at the transition state, the further development to instability can be blocked in a simpler and more efficient way, thereby preventing the occurrence of major instability disasters. Summary of the invention
[0004] The present invention proposes a subcritical state for identifying a transition state from stability to instability. The subcritical state involves the weakening of rock mechanical properties and changes in fracture mechanisms.
[0005] The specific technical solution is:
[0006] The precursor warning analysis method based on the subcritical state of the rock-stress system is to identify the subcritical state of the rock-stress system, which refers to the stability state of the rock-stress system corresponding to the external applied stress higher than the Kaiser stress of the rock and lower than the peak stress of the rock, and the external applied stress is between the yield stress and the peak stress; capture the monitoring characteristic information corresponding to the warning characteristic point I and the warning characteristic point II. Based on the monitoring characteristic information, an intelligent recognition model for rock shear slip precursors is constructed to achieve long-term prediction of rock instability and multi-level warning of short-term warning.
[0007] The method for determining the early warning characteristic point I and the early warning characteristic point II is:
[0008] The rock stress process under stress is divided into: OA initial and elastic stage, AB plastic deformation stage, BC destruction stage, CD residual stress stage. The change law of the rock-stress system stable state U is summarized as follows:
[0009] (1) OA stage, in the early and middle stages, it is in the stable state I, and in the later stages, it enters the metastable state II: At the initial stage of loading, the external stress is at a low level, and the rock corresponds to the initial and elastic stages. In the early and middle stages, the rock does not produce obvious fractures, and the primary crack closure event occurs, and the rock-stress system is in the stable state I. When the external stress increases to a certain extent, the primary cracks show small fractures, the primary cracks begin to expand slightly, and the rock-stress system enters the metastable state II. At this stage, the rock-stress system also has the ability to self-regulate.
[0010] (2) AB stage, metastable state II: the external stress continues to increase, and when it exceeds the yield stress σ A , the rock enters the plastic deformation stage. The primary cracks expand from the microscopic to the macroscopic scale, secondary cracks begin to develop, and the mechanical properties of the rock gradually deteriorate. The rock-stress system enters the metastable state II, and the system gradually loses its self-regulation ability. When the external stress reaches the limit stress σ B , the rock itself undergoes irreversible damage, the rock-stress system is at the critical position of instability, and the system enters the unstable state III in the next step.
[0011] (3) BC stage, instability state III: In this stage, the rock is unstable and the cohesion of the rock disappears. As the loading continues, the macro cracks show slip dislocation between the fracture surfaces, and the secondary cracks expand. The stress gradually decreases, but the rock does not completely collapse under the action of residual stress. The rock-stress system begins to seek a new equilibrium state.
[0012] (4) CD stage, steady state II: Under the influence of residual stress, the rock-stress system reaches a new equilibrium state. The new equilibrium state is unstable and is metastable state II. At this stage, the rock is unstable and a small stress disturbance can easily lead to unstable state III. The system has lost its self-regulation ability.
[0013] When the applied stress continues to change, the development of rock fracture undergoes a process of "damage recovery → damage irreversible → fracture stage evolution". Under the action of shear slip, the steady-state evolution process of the rock-stress system includes "stable state → metastable state I → metastable state II → unstable state III → metastable state I → metastable state II → unstable state III". There are three important nodes in this process, the starting point of irreversible damage, the early warning feature point I, and the early warning feature point II. The irreversible damage starting point is the beginning of irreversible damage to the rock-stress system, the boundary between the stable state and the metastable state I; the early warning feature point I, as the beginning of the early warning signal that triggers the instability of the rock-stress system, is the boundary between the metastable state I and the metastable state II; the early warning feature point II, as the short-term prediction point of instability of the rock-stress system, is the boundary between the metastable state II and the unstable state III.
[0014] The subcritical state of the rock-stress system is located between the warning characteristic point I and the warning characteristic point II, which is subdivided into metastable state I and metastable state II.
[0015] The present invention has the following technical effects:
[0016] (1) The scientific connotation of the rock-stress system is defined, involving the key properties of rock mechanical degradation under stress change conditions. The subcritical state of the rock-stress system refers to the stability state of the rock-stress system when the external applied stress is higher than the Kaiser stress of the rock and lower than the peak stress of the rock, and the external applied stress is between the yield stress and the peak stress, that is, the subcritical state.
[0017] (2) The subcritical state of the rock-stress system is proposed as the temporal and spatial characterization information of the precursor. The rock has both irreversible damage and destruction and has not lost its bearing capacity. The subcritical state is a special stability state, and the rock is extremely sensitive to stress changes. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the complex system state transition of the present invention;
[0019] Figure 2 It is a schematic diagram of the mechanical evolution process of the rock-stress system state of the present invention;
[0020] Figure 3 This is a diagram showing the evolution of the stability state of the rock-stress system of the present invention. DETAILED DESCRIPTION
[0021] The specific technical solution of the present invention is described in conjunction with the accompanying drawings.
[0022] 1. The state change process of rock-stress system;
[0023] like Figure 1 As shown in the figure, it is assumed that there are four equilibrium states in the stable state transition of a certain system, namely stable state a, unstable state b, stable state c and unstable state d. Stable state a and stable state c are at the bottom, and the left and right swings do not affect the change of the system state. The system is in equilibrium and the system itself is self-stable. Unstable state b and unstable state d are at the top, and the left and right swings can easily change the system state. The system is in a non-equilibrium state, and the system itself is not self-stable. The so-called self-stability refers to maintaining or adjusting the rock body in a relatively constant state, that is, keeping it within a certain range, and the rock is in dynamic equilibrium, but this relatively constant state does not have an accurate threshold.
[0024] The system state transition process can be summarized into three states: First, when the system is not disturbed by the outside world or there is no interaction between the system itself, its state will always be in the steady state a; second, when the external interference or the system's own action is so large that the system loses its self-regulation ability, it will leave the steady state a and enter the unstable state b. At this time, the system is out of balance and is the most unstable, and it is very easy to turn to another stable state c; third, the stable state c is at the bottom and is also relatively stable, but it is more active than the stable state a, and it will turn to the unstable state d under a small disturbance.
[0025] It is not difficult to see that there is a clear dividing line between the stable state a and the stable state c in terms of characterization. From the stable state a to the stable state c, we go through the unstable state b. The stable state c has two changing states, namely the unstable state b and the unstable state d. Then the stable state c can be regarded as a metastable state. Therefore, the change of the system from a relatively stable state to a metastable state is based on the system's own adaptability, and a process with nonlinear characteristics occurs.
[0026] 2. Characteristics of the stability state changes of the rock-stress system under external forces;
[0027] The development of rock failure under stress can also be regarded as a complex rock-stress system, and the stability of the system has undergone an evolutionary process of "adjustment → weakening → adjustment → weakening → instability". Under the continuous action of stress, the rock changes from self-stability to weakening effect, which is manifested as the development process of "initiation → expansion → nucleation → penetration" of cracks. Under the action of stress, the steady state of rock reflects a self-regulating ability of the rock body under the influence of stress, which enables it to maintain sufficient response ability and adaptability to the environment to the influence of external stress, so as to maintain the relative equilibrium state of the rock body.
[0028] like Figure 2 As shown in the figure, the rock-stress system is in a relatively stable state to maintain dynamic equilibrium in a certain degree of instability. The rock stress process under stress is divided into: OA initial and elastic stage, AB plastic deformation stage, BC destruction stage, CD residual stress stage. The change law of the rock-stress system stable state U is summarized as follows:
[0029] In the OA stage, the early and middle stages are in the stable state I, and the later stages enter the metastable state II: At the initial stage of loading, the external stress is at a low level, and the rock corresponds to the initial and elastic stages. In the early and middle stages, the rock does not produce obvious fractures, and the primary crack closure event occurs, and the rock-stress system is in the stable state I. When the external stress increases to a certain extent, the primary cracks show small fractures, the primary cracks begin to expand slightly, and the rock-stress system enters the metastable state II. At this stage, the rock-stress system also has the ability to self-regulate.
[0030] AB stage, metastable state II: external stress continues to increase, and when it exceeds the yield stress, the rock enters the plastic deformation stage. Primary cracks expand from microscopic to macroscopic scales, secondary cracks begin to germinate and develop, and the mechanical properties of the rock gradually deteriorate. The rock-stress system enters metastable state II, and the system gradually loses its self-regulation ability. When the external stress reaches the limit stress, the rock itself undergoes irreversible damage, the rock-stress system is at the critical position of instability, and the system enters instability state III in the next step.
[0031] BC stage, instability state III: In this stage, the rock is unstable and the cohesion of the rock disappears. As the loading continues, the macro cracks show slip dislocation between the fracture surfaces, and the secondary cracks expand. The stress gradually decreases, but the rock does not completely collapse under the action of residual stress. The rock-stress system begins to seek a new equilibrium state.
[0032] CD stage, steady state II: under the influence of residual stress, the rock-stress system reaches a new equilibrium state, which is unstable and metastable II. At this stage, the rock is unstable, and a small stress disturbance can easily turn it into unstable state III, and the system has lost its self-regulation ability.
[0033] Depend on Figure 2 It can be seen that "stable state I→metastable state II" is a continuous process. The rock-stress system has not become unstable, and the rock itself has not experienced any safety problems. The change of the rock-stress system from relative stability to metastable and then to instability is based on the adaptability of the rock itself, and the state change also has nonlinear characteristics.
[0034] Therefore, external stress affects the stability of the rock, and the continuous action of external stress accelerates the transition of the rock from stability to instability, that is, the stability of the rock is destroyed. The rock-stress system undergoes the system state transition process of "stable state I→metastable state II→unstable state III→metastable state II". "Metastable state II→unstable state III" and "unstable state III→metastable state II" correspond to the unstable left-right swinging state, that is, the critical state, which corresponds to two phase changes or critical transitions, K 1 , K 2 .
[0035] 3. Evolution model of stability state of rock-stress system;
[0036] According to the complex system state transition diagram ( Figure 1 ), the change from stable state to unstable state is not a linear process, and it will also experience metastable state. Under the action of external stress, the rock-stress system develops from stable to unstable, and there is a system state transition process of "stable state I→metastable state II→instable state III→metastable state II" ( Figure 2 ).comprehensive Figure 1 and Figure 2 Based on the description of the content, taking into account the several stages of stress change in the rock shear slip process and the several states of stability, the stability state evolution pattern of the rock-stress system is sorted out.
[0037] like Figure 3 As shown, the only rock that is not stressed is safe. When the applied stress continues to change, the development of rock fracture undergoes a process of "damage recoverable → damage irrecoverable → fracture stage evolution". Under the action of shear slip, the steady-state evolution process of the rock-stress system includes "stable state → metastable state I → metastable state II → unstable state III → metastable state I → metastable state II → unstable state III". There are three important nodes in this process, the starting point of irreversible damage, the early warning feature point I, and the early warning feature point II. The irreversible damage starting point is the beginning of irreversible damage to the rock-stress system, the junction of the stable state and the metastable state I; the early warning feature point I, as the beginning of the early warning signal that triggers the instability of the rock-stress system, is the junction of the metastable state I and the metastable state II; the early warning feature point II, as the short-term prediction point of instability of the rock-stress system, is the junction of the metastable state II and the unstable state III.
[0038] 4. The scientific connotation of the subcritical state of the rock-stress system;
[0039] Figure 3 The two valleys in the middle represent the stable state and metastable state I, respectively, indicating that the system state is relatively stable. Even if it is affected by stress, it mainly fluctuates in a small range in the valley; the two ridges on the left near the top of the mountain are steep and difficult to maintain stability. The rock-stress system lacks self-stability and can easily enter the top of the mountain under the influence of a slight change in external stress; the two tops of the mountain plus the ridge on the right represent the unstable state III, where it is almost impossible to maintain stability, and the rock-stress system has no self-stability at all. The subcritical state of the rock-stress system is located between the warning characteristic point I and the warning characteristic point II, and is subdivided into two states: metastable state I and metastable state II.
[0040] The scientific connotation of the subcritical state of the rock-stress system involves the key properties of rock mechanical degradation under stress change conditions. The subcritical state of the rock-stress system refers to the stability state of the rock-stress system where the external applied stress is higher than the Kaiser stress or yield stress of the rock and lower than the peak stress of rock failure. The external applied stress is between the yield stress and the peak stress, that is, the subcritical state. In this state, the rock has both irreversible damage and destruction and has not lost its bearing capacity. As a special stability state, the subcritical state means that the rock is extremely sensitive to stress changes.
[0041] 5. Precursor warning analysis based on subcritical state of rock-stress system
[0042] By identifying the subcritical state of the rock-stress system, the monitoring characteristic information corresponding to the warning characteristic point I and the warning characteristic point II is captured. Based on the monitoring characteristic information, an intelligent recognition model for rock shear slip precursors is constructed to achieve multi-level warnings for long-term prediction and short-term warning of rock instability.
Claims
1. A precursor warning analysis method based on the subcritical state of the rock-stress system, characterized by: By identifying the subcritical state of the rock-stress system, the subcritical state of the rock-stress system refers to the stability state of the rock-stress system corresponding to the external applied stress higher than the Kaiser stress of the rock and lower than the peak stress of the rock, and the external applied stress is between the yield stress and the peak stress; capturing the monitoring characteristic information corresponding to the early warning characteristic point I and the early warning characteristic point II; Based on the monitoring characteristic information, an intelligent recognition model for rock shear slip precursors is constructed to achieve long-term prediction and short-term multi-level warning of rock instability.
2. The precursor warning analysis method based on the subcritical state of the rock-stress system according to claim 1 is characterized in that: The method for determining the early warning characteristic point I and the early warning characteristic point II is: The rock stress process under stress is divided into: OA initial and elastic stage, AB plastic deformation stage, BC destruction stage, CD residual stress stage. The change law of the rock-stress system stable state U is summarized as follows: (1) OA stage: the early and middle stages are in stable state I, and the late stages enter metastable state II: At the initial stage of loading, the external stress is at a low level, and the rock corresponds to the initial and elastic stages; in the early and middle stages, the rock does not produce obvious fractures, and primary fracture closure events occur, and the rock-stress system is in stable state I; When the external stress increases to a certain extent, the primary cracks will show tiny ruptures, and the primary cracks will begin to expand slightly, and the rock-stress system will enter the metastable state II. In this stage, the rock-stress system still has the ability to self-regulate. (2) AB stage, metastable state II: the external stress continues to increase, and when it exceeds the yield stress σ A , the rock enters the plastic deformation stage; the primary cracks expand from the microscopic to the macroscopic scale, the secondary cracks begin to develop, and the mechanical properties of the rock gradually deteriorate; the rock-stress system enters the metastable state II, and the system gradually loses its self-regulation ability; when the external stress reaches the limit stress σ B , the rock itself is irreversibly damaged, the rock-stress system is at the critical position of instability, and the system enters the instability state III in the next step; (3) BC stage, instability state III: In this stage, the rock is unstable and the cohesion of the rock disappears; loading continues, and slip dislocation occurs between the fracture surfaces of the macro cracks, while the secondary cracks expand; the stress gradually decreases, but the rock does not completely collapse under the action of residual stress; the rock-stress system begins to seek a new equilibrium state; (4) CD stage, steady state II: under the influence of residual stress, the rock-stress system reaches a new equilibrium state. The new equilibrium state is unstable and is metastable state II. At this stage, the rock is unstable and a small stress disturbance can easily lead to unstable state III. The system has lost its self-regulation ability. When the applied stress continues to change, the rock fracture development undergoes a process of "damage recoverable → damage irrecoverable → fracture stage evolution"; under the action of shear slip, the steady-state evolution process of the rock-stress system includes "stable state → metastable state I → metastable state II → unstable state III → metastable state I → metastable state II → unstable state III", and there are three important nodes in this process, namely, the irreversible damage starting point, the warning characteristic point I, and the warning characteristic point II; The irreversible damage starting point is the beginning of irreversible damage of the rock-stress system, the boundary between the stable state and the metastable state I; Early warning feature point I, as the beginning of the early warning signal for the instability of the rock-stress system, is the junction of metastable state I and metastable state II; Early warning feature point II, as the short-term prediction point for the instability of the rock-stress system, is the junction of metastable state II and unstable state III; The subcritical state of the "rock-stress" system is located between the warning characteristic point I and the warning characteristic point II, which is subdivided into metastable state I and metastable state II.