CN110865241B - Fracture stability evaluation system and method - Google Patents
Fracture stability evaluation system and method Download PDFInfo
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- CN110865241B CN110865241B CN201910969405.9A CN201910969405A CN110865241B CN 110865241 B CN110865241 B CN 110865241B CN 201910969405 A CN201910969405 A CN 201910969405A CN 110865241 B CN110865241 B CN 110865241B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
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- G01R29/14—Measuring field distribution
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/082—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices operating with fields produced by spontaneous potentials, e.g. electrochemical or produced by telluric currents
Abstract
The invention relates to a fracture stability evaluation system and method. The fracture stability evaluation system comprises a plurality of monitoring stations, a networking computing device and an evaluation computing device, wherein each monitoring station comprises at least three monitoring electrodes, a monitoring instrument and a local computing device, the monitoring instrument is connected with each monitoring electrode, and the difference of the electric physical quantity between the two monitoring electrodes in each monitoring channel is detected; the local computing equipment draws an equipotential line of a breaking electric field in the breaking zone by adopting an interpolation method according to the electro-physical quantity difference and sends the equipotential line to the networked computing equipment; and the networked computing equipment determines the intersecting part of the piezoelectric part direction of each fracture electric field as the piezoelectric part of the fracture zone according to the equipotential lines, and the evaluation computing equipment inputs the position parameters of the piezoelectric part and the preset size parameters of the piezoelectric part into the fracture stability evaluation model. The fracture stability evaluation system can improve the accuracy of fracture zone stability evaluation.
Description
Technical Field
The invention relates to the field of ground electric field detection, in particular to a fracture stability evaluation system and method.
Background
The fracture electric field refers to an electric field distributed in and near a fracture zone, and as shown in fig. 1, a prerequisite for the formation of the fracture electric field is the existence of compressive stress, and the compressive stress is the interaction force of two fractured disk blocks, which can be clarified from the origin of an earthquake. The stress concentration is used for explaining the pressure source in the piezoelectric effect forming the fracture electric field, and then the piezoelectric minerals which are orderly arranged are needed. The fact that the depth of the continental earthquake source is more than 5-25km in the so-called continental earthquake layer shows that the stress concentration point on the fracture surface mainly appears in the deep part of the crust 5-25km below the surface, and the depth is the distribution range of the granite layer. Therefore, when the fracture is cut to the depth range, orderly arranged quartz minerals are necessarily present, and the piezoelectric effect is naturally generated when stress concentration occurs on the two disks of the fracture, namely the source of an electric field in the fracture. According to the principle, the broken piezoelectric part is a blocking part which is used for blocking relative motion of two broken discs on a section and is a potential earthquake-generating source, namely a piezoelectric part. The intensity of the fracture electric field is therefore only related to the stress of this obstacle, while the size of the obstacle depends on the roughness of the fracture, independently of the mechanical and kinematic properties of the fracture.
As shown in fig. 2, the piezoelectric effect of the piezoelectric portion can be regarded as a "power source", however, the power source may exist under the earth's surface at a depth of several kilometers or even tens of kilometers, and a human being needs to have a concept of "wire" for observing the power source on the earth's surface, and the "wire" is a fracture itself. According to the existing ultra-deep drilling data, the deep part of the land crust still has water, and the water can be used as a current carrier in the fracture of crack development, and the piezoelectric current generated in the deep part of the fracture can reach a shallow area due to the good conductivity of the current carrier, so that a fracture electric field is formed.
The strength of different parts of the fracture electric field is different, and the electric field strength is larger as the fracture electric field is closer to a power supply. Relative to the interior of the fractured zone, the upper and lower discs have a much lower water content than the fractured zone itself due to the failure of the fracture to develop, so that the two discs are substantially insulated. When the piezoelectric current in the fracture zone is conducted to the surface, it will contact with the superficial water to generate "leakage phenomenon". In other words, the pre-earthquake electrical anomaly measured by the above methods is essentially a "leakage electric field" (see fig. 2) formed by the radiation effect of the fracture electric field in the shallow aquifer, and the "leakage electric field" is essentially the extension of the fracture electric field at the surface region. We will refer to this as the shallow earth diffusion electric field of the fracture electric field, hereinafter referred to as the fracture diffusion electric field.
The existing earthquake prediction method actually predicts the earthquake without any time by using the limit time prediction of the time difference between electromagnetic waves and mechanical waves when the earthquake actually occurs. At present, the academia also researches the earthquake through some models, for example, open source numerical simulation software undermorld developed by the university of melbourne and commercial software abaqus, after a researcher determines the size and material parameters of a numerical simulation model corresponding to a monitoring area according to the monitoring area, an evaluation model of fracture stability can be established according to the potential pregnancy area of a fracture zone or the depth of a piezoelectric part and the size of the piezoelectric part, so that the stress tensor change of the piezoelectric part can be calculated according to the model, and when the stress tensor of the piezoelectric part reaches a critical value, the stability of the fracture zone can be influenced, possibly causing the occurrence of the earthquake. However, the existing natural electric field method cannot accurately detect the piezoelectric position of the fracture electric field, i.e., the position of the piezoelectric position of the fracture zone, so that the fracture stability evaluation model cannot accurately evaluate the stability of the fracture zone.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a fracture stability evaluation system and method, which can improve the accuracy of fracture zone stability evaluation.
In a first aspect, an embodiment of the present invention provides a fracture stability evaluation system, including:
a plurality of monitoring stations and a networked computing device, wherein each monitoring station comprises:
the system comprises at least three monitoring electrodes, a monitoring instrument and local computing equipment, wherein every two monitoring electrodes form a group of monitoring channels;
the at least three electrodes are positioned on the same plane, the plane is parallel to the section of the fracture and fragmentation zone, and the at least two monitoring electrodes are used as depth electrodes and are arranged in the fracture and fragmentation zone below the bedrock surface through detection drill holes;
every two monitoring electrodes are not positioned on the same horizontal plane at the same time, or the numerical value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of every monitoring electrode is consistent;
the monitoring instrument is connected with each monitoring electrode, detects the electrical physical quantity difference between the two monitoring electrodes in each group of monitoring channels, and sends the electrical physical quantity difference to the local computing equipment;
the local computing equipment performs interpolation of equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so that an equipotential line of a breaking electric field in a breaking zone is drawn, and the equipotential line is sent to the networked computing equipment;
the networked computing equipment determines the direction of the piezoelectric part of the fracture electric field detected by each monitoring station according to the equipotential lines of the fracture electric field in the fracture zone outlined by the local computing equipment of each monitoring station, wherein the direction of the piezoelectric part of the fracture electric field detected by each monitoring station is vertical to the equipotential lines of the fracture electric field; determining the intersecting position of the directions of the piezoelectric parts of the fracture electric fields as the piezoelectric parts of the fracture zone according to the directions of the piezoelectric parts of the fracture electric fields determined by each monitoring station;
the evaluation calculation equipment inputs the position parameter of the piezoelectric part and a preset piezoelectric part size parameter into a fracture stability evaluation model, and adjusts the preset piezoelectric part size parameter input into the fracture stability evaluation model, so that the electrophysical quantity difference of the at least three electrodes, which is simulated and output by the fracture stability evaluation model, approaches to the electrophysical quantity difference of the at least three electrodes detected by the monitoring instrument.
Further, the number of the depth electrodes per monitoring station is at least three, and each depth electrode is installed in a fracture zone below the bedrock face by a different probe borehole.
Furthermore, every two depth electrodes of each monitoring station form a group of monitoring channels, the monitoring instrument is connected with each depth electrode, and the difference of the electrical physical quantity between the two depth electrodes in each group of monitoring channels is detected;
alternatively, the first and second electrodes may be,
every monitoring station still includes one and sets up the superficial electrode in the superficial soil layer in broken area, and every two degree of depth electrodes constitute a set of monitoring survey way, monitoring instrument is connected with every degree of depth electrode and superficial electrode to detect the electro-physical quantity difference between every degree of depth electrode and the superficial electrode, and obtain the electro-physical quantity difference between two degree of depth electrodes in every group monitoring survey way that constitutes by the degree of depth electrode according to the electro-physical quantity difference between every degree of depth electrode and the superficial electrode.
Further, the number of the depth electrodes of each monitoring station is at least three, and wherein at least two depth electrodes are installed in the fracture and fragmentation zone below the bedrock face through the same probe borehole, the installation depth of the two monitoring electrodes in the probe borehole being different.
Further, the at least three monitoring electrodes of each monitoring station include a superficial electrode and two depth electrodes;
the shallow electrodes are installed in shallow soil layers of the fracture and fracture zone, and the two deep electrodes are installed in the fracture and fracture zone below the surface of the bedrock through different detection drill holes.
In a second aspect, an embodiment of the present invention provides a method for evaluating fracture stability, including the following steps:
inputting a position parameter of a piezoelectric part and a preset size parameter of the piezoelectric part, which are acquired from networked computing equipment, into a fracture stability evaluation model; the networked computing equipment acquires equipotential lines of a breaking electric field of a breaking broken belt, which are drawn by local computing equipment of each monitoring station in a plurality of monitoring stations, and determines the direction of a piezoelectric part of the breaking electric field detected by each monitoring station according to the equipotential lines of the breaking electric field of the breaking broken belt, which are drawn by the local computing equipment of each monitoring station; the direction of the piezoelectric part of the fracture electric field detected by each monitoring station is vertical to the equipotential line of the fracture electric field; each monitoring station includes: the system comprises at least three monitoring electrodes, a monitoring instrument and local computing equipment, wherein every two monitoring electrodes form a group of monitoring channels; the at least three electrodes are positioned on the same plane, the plane is parallel to the section of the fracture and fragmentation zone, and the at least two monitoring electrodes are used as depth electrodes and are arranged in the fracture and fragmentation zone below the bedrock surface through detection drill holes; every two monitoring electrodes are not positioned on the same horizontal plane at the same time, or the numerical value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of every monitoring electrode is consistent; the monitoring instrument is connected with each monitoring electrode, detects the electrical physical quantity difference between the two monitoring electrodes in each group of monitoring channels, and sends the electrical physical quantity difference to the local computing equipment; the local computing equipment interpolates the equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so that the equipotential lines of the breaking electric field in the breaking zone are drawn; the networking computing equipment determines the intersecting position of the piezoelectric position direction of each fracture electric field as the piezoelectric position of the fracture zone according to the piezoelectric position direction of the fracture electric field determined by each monitoring station;
and determining the intersecting part of the directions of the piezoelectric parts of the fracture electric fields as the piezoelectric part of the fracture zone according to the directions of the piezoelectric parts of the fracture electric fields determined by each monitoring station.
Further, the number of the depth electrodes per monitoring station is at least three, and each depth electrode is installed in a fracture zone below the bedrock face by a different probe borehole.
Furthermore, every two depth electrodes of each monitoring station form a group of monitoring channels, the monitoring instrument is connected with each depth electrode, and the difference of the electrical physical quantity between the two depth electrodes in each group of monitoring channels is detected;
alternatively, the first and second electrodes may be,
every two depth electrodes of every monitoring station constitute a set of monitoring survey way, monitoring instrument and each depth electrode and one set up in the shallow electrode connection in the shallow soil layer of broken zone to detect the electrical physical quantity difference between every depth electrode and the shallow electrode, and obtain the electrical physical quantity difference between two depth electrodes in every group monitoring survey way that constitutes by the depth electrode according to the electrical physical quantity difference between every depth electrode and the shallow electrode.
Further, the number of the depth electrodes of each monitoring station is at least three, and wherein at least two depth electrodes are installed in the fracture and fragmentation zone below the bedrock face through the same probe borehole, the installation depth of the two monitoring electrodes in the probe borehole being different.
Further, the at least three monitoring electrodes of each monitoring station include a superficial electrode and two depth electrodes;
the shallow electrodes are installed in shallow soil layers of the fracture and fracture zone, and the two deep electrodes are installed in the fracture and fracture zone below the surface of the bedrock through different detection drill holes.
In the embodiment of the application, a plurality of monitoring stations and a networking computing device are arranged in an area where a fracture diffusion electric field is abnormal, each monitoring station is provided with at least three monitoring electrodes in the fracture zone in parallel with the section of the fracture zone to form a plurality of groups of monitoring channels, a monitoring instrument detects the difference of the electric physical quantity between the two monitoring electrodes in each group of monitoring channels, a local computing device method interpolates the equal difference point of the electric physical quantity between the two monitoring electrodes in each group of monitoring channels so as to draw out the equal potential lines of the fracture electric field strength of the fracture zone, each monitoring station can determine the direction of an electric field line because the equal potential lines are vertical to the electric field lines, the networking device can determine the piezoelectric part of the fracture electric field, namely the position parameters of the piezoelectric part in the fracture zone according to the directions of the electric field lines determined by the plurality of monitoring stations, and the position parameter and the size of the preset piezoelectric part are input into a fracture stability evaluation model, and the model parameter is continuously adjusted by comparing the simulation result with the actual monitoring data, so that the accuracy of fracture and fracture zone stability evaluation is improved.
For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.
Drawings
FIGS. 1 and 2 are schematic diagrams illustrating the principle of the formation of the breaking electric field;
FIG. 3 is a schematic block diagram of the fracture stability evaluation system of the present invention shown in one exemplary embodiment;
FIG. 4 is a schematic block diagram of monitoring station number 1 of the fracture stability assessment system of the present invention shown in one exemplary embodiment;
FIG. 5 is a schematic view of the internal connections of monitoring station number 1 of the fracture stability assessment system of the present invention shown in one exemplary embodiment;
FIGS. 6A and 6B are schematic views of drill placement locations for monitoring a borehole shown in an exemplary embodiment;
FIG. 7 is a schematic illustration of interpolation of electrical physical quantity isodyne points in a fractured fracture zone shown in an exemplary embodiment;
FIG. 8 is a schematic diagram illustrating the principle of determining electric field direction from fracture electric field equipotential lines in an exemplary embodiment;
FIG. 9 is a schematic block diagram of monitoring station number 1 of the fracture stability assessment system of the present invention shown in one exemplary embodiment;
FIG. 10 is a schematic block diagram of monitoring station number 1 of the fracture stability assessment system of the present invention shown in one exemplary embodiment;
FIG. 11 is a schematic block diagram of monitoring station number 1 of the fracture stability assessment system of the present invention shown in one exemplary embodiment;
FIG. 12 is a flow chart illustrating a method of evaluating fracture stability of the present invention in one exemplary embodiment.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the relevant aspects of the present invention are shown in the drawings.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present invention. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.
When the fracture-propagating electric field in the region is abnormal, its equipotential lines from the plane should appear to be convex away from the fracture zone, or the line spacing of the equipotential lines may become dense. However, in any form, the electrophysical quantity of the abnormal portion is generally increased and strongly increased, such as: a voltage rise, a current increase, or an increase in the electric field strength. When the human interference factors are preliminarily eliminated, the abnormity represents the direct reflection of the fracture electric field abnormity on the surface. Once the situation is determined to occur, the fracture electric field monitoring stations can be built on the abnormal area, a combined monitoring plane or a folding surface can be formed among the multiple monitoring stations in the fracture and fragmentation zone, therefore, the attenuation direction of the fracture electric field moving through each monitoring station is taken as a straight line, and the intersecting position of the straight lines is the source position causing the fracture electric field to be abnormal. Because shallow monitoring electrodes are generally not required for the monitoring station, factors of manual interference can be assisted to be eliminated when only deep drilling electrodes are used. Thus, theoretically, two or more monitoring stations are required (two straight lines intersect to determine the intersection). Generally, taking two monitoring stations as an example, the two monitoring stations should be established at the edge of the abnormal region of the fracture diffusion electric field, and then additional monitoring stations (the number is determined according to the monitoring effect and the size of the abnormal region) are added according to the monitoring effect to increase the monitoring density.
The fracture stability evaluation model in the embodiment of the application can be a commonly-used numerical simulation model in the prior art, and the key of the numerical simulation model lies in determining the size and material parameters of the model, wherein the size of the model is determined by the size of a monitoring area. The material parameters are set primarily by the layering of the rock core, while fracture is also considered as a discontinuous interface of these layers. The material parameters between the layers, including viscosity, plasticity and elasticity, can adopt the existing parameters, and the boundary conditions, including speed boundary and temperature boundary, need to be determined according to the actual geological data and geophysical data of the monitored area. The following examples illustrate:
the monitoring area is assumed to be the core area of the Zhujiang Delta, namely the three-water basin, the northwest river Delta and the east river Delta. Before simulation is carried out by using a fracture stability evaluation model, a pre-model of an evolution mechanism needs to be set in the region, and the bead deltoid south China coastal region is a part of a newly-born south China sea evolution region. The causative model for south sea includes passive expansion, active expansion, dextrorotation extrusion, broken block equalization, etc. The method selects the broken blocks proposed by the qiu swallow et al (2010) to be balanced into a preposed logic model (the model is selected according to the understanding of a modeler on the geological background and the evolution process of the region, but all logic models can be simulated).
The simulations were assumed to use rheological software with visco-plastic-elastic constitutive equations. The triangular area of the bead to be simulated has a size of about 150 km/150 km and a rock circle thickness of about 95 km. Then, the size of the designed model is 150 × 95. The numerical values in the model are unit, namely, the numerical values can be set according to a certain scale (used in physical modeling, and the scale is not required to be considered in digital modeling). The structure of the rock circle in the bead triangular region, namely the thicknesses of an upper shell, a middle shell, a lower shell and a rock mantle, has ready information in a geophysical prospecting team in the region, and the digital model in the bead triangular region is subjected to zone division in the model according to the existing parameters. The material parameters and physical parameters between the layers of the rings in the model are set according to the existing experimental petrology parameters, for example, the representative rock of the upper middle ground shell is granite, the viscosity coefficient of the rock in a solid state is generally 1e21 Pa/s, and the thermal expansion coefficient, the thermal conductivity coefficient, the specific heat capacity, the Poisson ratio and the like can be set according to the parameters of the granite. The lower crust is typically basalt, while the rock mantle can be set as olivine. After the material parameters are set, boundary conditions, mainly temperature and velocity boundaries, need to be applied to the model. The temperature boundaries and the temperature fields are set according to the existing ground temperature data.
Fig. 3 to 6 are schematic structural diagrams of an evaluation system of fracture stability in an embodiment of the present application, in this embodiment, the evaluation system of fracture stability is provided with a monitoring station No. 1 and a monitoring station No. 2 in an abnormal region of a fracture propagation electric field, and in some examples, the number of the monitoring stations may also be multiple, for example, in fig. 3, a B-type monitoring station located between the monitoring station No. 1 and the monitoring station No. 2 is additionally provided according to a preliminary detection result of the monitoring station No. 1 and the monitoring station No. 2.
The structure and the working principle of each monitoring station in the embodiment of the application are approximately the same, and the structure and the working principle of the monitoring station are described below by taking the monitoring station No. 1 as an example.
As shown in fig. 4 and 5, monitoring station No. 1 comprises three monitoring electrodes a, b and c for detecting the electro-physical quantities in the fractured fracture zone, a monitoring instrument e and a local computing device f.
The monitoring station number 1 in this embodiment should be limited to the visual range of the naked eye in an open space, such as a school, or a building.
The fracture zone corresponding to monitoring station No. 1 in this embodiment is not only a tensile fracture zone, but also the same for reverse fracture and slip fracture (corresponding to compressive fracture and torsional fracture zones), because the generation of fracture electric field is not related to the mechanical and kinematic properties of fracture, but only to the roughness of fracture (as explained in the above theory). The fracture zone is a regional deep fracture for controlling landform, old stratum dislocation can be seen by naked eyes, or small ore control fractures or filling dikes are not considered, because the fractures, fractures or faults can not cause large-scale tectonic earthquakes.
As shown in fig. 4, the monitor electrodes a, b and C are installed as depth electrodes in the fracture zone below the bedrock face by probe boreholes A, B and C, respectively. In order to prevent collapse of the fourth tied-up layer and weathered bed rock layer and shallow water layer changes from affecting the probe borehole, the probe boreholes A, B and C are provided with casing for collapse and water isolation in the corresponding hole sections of the fourth tied-up layer and weathered bed rock layer.
In the embodiment, every two monitoring electrodes in the monitoring electrodes a, b and c form a group of monitoring traces, the installation positions of the monitoring electrodes a, b and c in the fracture and fragmentation zone are located on the same plane, and the plane is parallel to the section of the fracture and fragmentation zone. The fracture surface of the fracture zone is a surface of the fracture zone intersected with the fracture upper plate or the fracture lower plate at a vertical distance. In fig. 4 and the following drawings, the connection line between the two monitoring electrodes indicates that the two monitoring electrodes form a group of monitoring channels, and does not mean that the two monitoring electrodes are directly communicated through a wire.
In the embodiment, the mounting depths of the monitoring electrodes a, b and c are different, namely, each monitoring electrode is not positioned on the same horizontal plane with other monitoring electrodes at the same time; or the value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of each monitoring electrode is consistent.
Based on the principle that a straight line can be determined by two points and a plane can be determined by two crossed straight lines, a monitoring plane can be constructed in the broken fracture zone by utilizing at least three monitoring electrodes which are not on the same straight line and are arranged in the broken fracture zone. Meanwhile, because each monitoring electrode is respectively arranged in different drill holes, the inclination angle of the monitoring plane can be controlled by adjusting the installation depth of the electrodes so as to be parallel to the fracture surface.
In other examples, the number of monitoring electrodes may also be other numbers greater than 3. In some examples, the fracture stability evaluation system may include, in addition to the depth electrode, a superficial electrode disposed in a superficial soil layer of the fracture fragmentation zone, the superficial electrode and the other depth electrode being located on a plane parallel to the fracture zone if the superficial electrode and the other depth electrode form a survey, or the superficial electrode and the other depth electrode being located on a plane parallel to the fracture zone if the superficial electrode and the other depth electrode do not form a survey.
In some examples, the sleeve includes a steel layer and a PVC layer, the steel layer being wrapped around the PVC layer. As shown in fig. 6A and 6B, the drill placement position of the monitor drill hole depends on the shape of the fractured zone, and the higher the fracture shape, the closer the opening position is to the fractured zone.
As shown in fig. 5, the monitoring instrument e is respectively connected to the reference electrode and each of the depth electrodes a, b, and c through a cable, and a voltage or current detection circuit is provided in the monitoring instrument e, and is configured to detect an electrophysical quantity difference between the electrophysical quantities detected by each two depth electrodes in the fracture zone in real time, and send the electrophysical quantity difference to the local computing device f.
And the local computing equipment f interpolates the equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and takes one monitoring electrode as a reference point to connect the equal difference points of the electro-physical quantities of different groups of monitoring channels, so as to draw out an equipotential line of the fracture electric field in the fracture and fragmentation zone, wherein the reference point is preferably the point with the relatively minimum electric potential or the relatively maximum electric potential.
The local computing equipment f can be a computer or a server or special experimental equipment, analysis software is installed in the computer, interpolation of the electro-physical quantity and delineation of equipotential lines of a fracture diffusion electric field of a superficial soil layer can be completed, and the delineated equipotential lines are sent to the networked computing equipment g.
The electrical physical quantity in the present application may be a current and/or a voltage, and the following description will be made with reference to the voltage, that is, the electrical physical quantity difference is a voltage difference between the reference electrode and each superficial electrode, and the difference point of the electrical physical quantity is a difference point of the voltage.
As shown in fig. 7, in an example, fig. 7 is a schematic diagram illustrating the principle of interpolating the difference point of the electrical physical quantity between two monitoring electrodes in each monitoring trace by interpolation method in the embodiment of the present application, where the depth electrodes a, b, c form a monitoring plane, and the monitoring instrument can obtain the voltage differences Δ Uab, Δ Ubc, and Δ Uac between the trace ab, trace bc, and trace ac, and since the distances (l1, l2, l3) between the depth electrodes a, b, and c are known, in an ideal state, if the voltage is varying, the attenuation dU of the voltage difference per unit distance between the two electrodes can be obtained by dividing the voltage difference between the two electrodes by the distance between the two electrodes, for example, by Δ Ubc/l2, and the attenuation dU per unit distance of the voltage difference is obtained in millivolts/meter (mV/m). Since Δ Ubc is a vector, all voltage changes in the direction along the electrodes b, c can be found by multiplying dU by the distance between the electrodes b, c. Therefore, the interpolation is not a direct potential line of the electric field, but a difference point of the electric physical quantity, that is, a difference point of the voltage.
The local computing device f may perform voltage equal difference point interpolation between two monitoring electrodes in each group of monitoring channels according to the set interpolation distance, that is, the set distance between two adjacent interpolation points is the same. In some examples, the voltage equal difference point between two monitoring electrodes in each group of monitoring traces may also be interpolated according to the set difference of the electrical physical quantity, that is, the voltage difference between two adjacent interpolation points is the set voltage difference.
In fig. 7, the voltage differences Δ Uab, Δ Ubc, and Δ Uac are 500mV, 200mV, and 700mV, respectively, and the distances l1, l2, l3 are 50 meters, 40 meters, and 70 meters, respectively. If the interpolation of the voltage equal difference point between the two monitoring electrodes in each group of monitoring measurement is carried out according to the set interpolation distance, the interpolation can be carried out between the monitoring electrodes by adopting an interpolation method through the set interpolation distance l. Since the interpolation distance l is controllable, the size of each segment voltage isodyne is directly dependent on the measured values of the voltage difference between the two monitoring electrodes, i.e., Δ Uab, Δ Ubc, and Δ Uac. Taking 10m as an example of interval interpolation, the dU between the monitoring electrodes a and b is 500mV/50m is 10 mV/m; and (4) performing interpolation, wherein the voltage difference of one interpolation point nearest to the monitoring electrode a from the monitoring electrode a to the monitoring electrode b is 10mV/m by 10 m-100 mV.
Therefore, after the interpolation of the voltage equal difference points is completed, the voltage equal difference points with the same voltage difference with the electrode a in different groups of monitoring channels can be connected by taking the monitoring electrode a as a reference point, and the equipotential lines of the breaking electric field in the breaking and breaking zone can be drawn. As shown in fig. 6, if the monitoring electrode a is taken as a reference point, the voltage difference between the voltage equal difference between the monitoring electrodes b, c and the voltage difference between the monitoring electrode a are 550mV, 600mV, and 650mV, respectively.
In other examples, any monitoring electrode that is convenient to calculate may be used as the reference point, and if the number of monitoring electrodes is larger, a plurality of reference points may be included.
In order to make the drawn equipotential lines have a larger range, a larger number of monitoring electrodes may be provided, or interpolation of voltage equipotential points may be performed in regions other than the monitoring electrodes a, b, and c by using an extrapolation method. For example, the voltage difference of the monitoring electrode b at the first interpolation point far from the monitoring electrode a on the straight line where the monitoring electrodes a and b are located is 500mV +10mV/m 10 m-600 mV; the voltage difference of the monitoring electrode c at the first interpolation point far away from the monitoring electrode a on the straight line where the monitoring electrodes a and c are positioned is 700mV +10mV/m 10 m-800 mV.
In other examples, the attenuation variable dU may also be a function of the distance l, i.e. a non-uniform variation. Then dU can be calculated more accurately by differentiation, which is basically consistent with the concept of acceleration differentiation, except that the latter is the change in velocity over time.
As shown in fig. 8, the equipotential lines are perpendicular to the electric field lines, and the density degree of the equipotential lines can reflect the speed of the change of the electric potential in the electric field, and the denser the equipotential lines are, it indicates that the electric potential in the electric field is reduced to the next level by a shorter distance, which indicates that the electric field strength is smaller; the more sparse the equipotential lines, the more the potential in the electric field decreases over a longer distance to the next level, indicating a greater electric field strength.
The networked computing device g is connected with the local computing device f in each monitoring station, the networked computing device can be a computer or a server or special experimental equipment, and analysis software is installed in the computer.
As shown in fig. 3, the networked computing device g obtains equipotential lines of the fracture electric field outlined by the local computing device f in each monitoring station, and determines the direction of the piezoelectric portion of the fracture electric field detected by each monitoring station, where the piezoelectric portion of the fracture electric field detected by each monitoring station is in a direction perpendicular to the equipotential lines of the fracture electric field because the attenuation direction of the fracture electric field is in an upward direction.
And the networking computing equipment g also determines the intersecting part of the directions of the piezoelectric parts of the fracture electric fields as the piezoelectric parts of the fracture zone according to the directions of the piezoelectric parts of the fracture electric fields determined by each monitoring station.
Specifically, the networked computing device g may be a straight line perpendicular to the equipotential lines of the fracture electric field determined by each monitoring station, since the depth of the piezoelectric portion generating the fracture electric field is significantly greater than the depth of the monitoring electrode, the upward direction of the straight line is the attenuation direction of the fracture electric field, the upward direction of the straight line is the direction of the piezoelectric portion generating the fracture electric field, and the point where the straight lines perpendicular to the equipotential lines of the multiple monitoring stations intersect in the downward direction is the piezoelectric portion of the fracture electric field, i.e., the piezoelectric portion in the fracture and fragmentation zone.
In other examples, the number of monitoring stations may be other numbers greater to allow more accurate detection of the piezoelectric sites.
The networked computing device g is connected with an evaluation computing device h, the networked computing device g sends the calculated position parameters of the piezoelectric part of the fracture and fragmentation zone to the evaluation computing device h, the evaluation computing device h can be a computer or a server or a special experimental device, a fracture stability evaluation system is installed in the computer, and in some examples, the evaluation computing device h and the networked computing device can also be the same device.
The evaluation calculation device inputs the position parameter of the piezoelectric portion and a preset piezoelectric portion size parameter into the fracture stability evaluation model after setting the size of the fracture stability evaluation model and the boundary condition, namely the material composition parameter, so that the fracture stability evaluation model can calculate the stress tensor (sigma) accumulated by the piezoelectric portion according to the parameters and calculate the electric quantity accumulated by the piezoelectric portion according to the formula Q & d & sigma, wherein Q is the electric quantity, d is the piezoelectric modulus, and d is a constant, if the fracture generates the piezoelectric effect at a deep part, the piezoelectric point is always positioned in the granite layer, and the piezoelectric modulus of the granite is known (1.65-13.66C/N & lt 10-15 & gt).
After calculating the electric quantity Q accumulated at the piezoelectric part, because the fracture zone is used as a lead wire, the actual conductive material in the fracture zone is free water filled in the fracture zone, the resistivity R of the water is a constant or variable changing with temperature, meanwhile, because the electric quantity Q changes with time and the time t is given according to the simulation time, the fracture stability evaluation model can calculate the potential difference U (voltage) of the fracture electric field at each part of the fracture zone according to the formula U which is Q multiplied by R/t.
The evaluation calculation device may adjust the piezoelectric portion size parameter in the fracture stability evaluation model as a preset value input value by comparing the potential difference of the fracture and fracture zone calculated by the fracture stability evaluation system at the three electrodes a, b, and c with the potential difference actually detected by the three electrodes, and adjust the preset piezoelectric portion size parameter input to the fracture stability evaluation model, so that the electrophysical quantity difference of the fracture and fracture zone simulated and output by the fracture stability evaluation model at the at least three electrodes approaches the electrophysical quantity difference of the at least three electrodes detected by the monitoring instrument.
According to the embodiment of the application, the simulation result is compared with the actual monitoring data, the model is continuously adjusted and repeatedly operated, so that the error between the simulation result and the monitoring data can be reduced, and the approaching process is realized. When the error is less than the maximum acceptable limit, the simulation model can be considered to be authentic. And the time of the fault block activity given by the model operation is the time of the earthquake occurrence. And (3) taking the occurrence of fracture diffusion electric field abnormity as the time for starting simulation, and comparing the total duration time until the model generates the fracture block activity with the real time to know how long the earthquake occurs.
In the embodiment of the application, a plurality of monitoring stations and a networking computing device are arranged in an area where a fracture diffusion electric field is abnormal, each monitoring station is provided with at least three monitoring electrodes in the fracture zone in parallel with the section of the fracture zone to form a plurality of groups of monitoring channels, a monitoring instrument detects the difference of the electric physical quantity between the two monitoring electrodes in each group of monitoring channels, a local computing device method interpolates the equal difference point of the electric physical quantity between the two monitoring electrodes in each group of monitoring channels so as to draw out the equal potential lines of the fracture electric field strength of the fracture zone, each monitoring station can determine the direction of an electric field line because the equal potential lines are vertical to the electric field lines, the networking device can determine the piezoelectric part of the fracture electric field, namely the position parameters of the piezoelectric part in the fracture zone according to the directions of the electric field lines determined by the plurality of monitoring stations, and the position parameter and the size of the preset piezoelectric part are input into a fracture stability evaluation model, and the model parameter is continuously adjusted by comparing the simulation result with the actual monitoring data, so that the accuracy of fracture and fracture zone stability evaluation is improved.
In an exemplary embodiment, as shown in fig. 9, the monitoring station No. 1 may further include a common superficial electrode d installed in a superficial soil layer in the fracture zone on the basis of at least three monitoring electrodes in the above-mentioned embodiment, and the superficial electrode d has no installation depth requirement, and in some cases, only needs to be simply buried in the soil layer, but the electrodes should be prevented from being exposed on the surface, and the isolation of artificial electromagnetic radiation is better. In other examples, the superficial electrode d may be installed in a superficial soil layer in one of the upper or lower fracture plates for easy installation.
In this embodiment, still, each two depth electrodes form a group of monitoring traces, and the monitoring instrument is connected to each depth electrode and also connected to the common superficial electrode d, and monitors a voltage difference between each depth electrode and the common superficial electrode d, so as to obtain a voltage difference between two depth electrodes in each group of monitoring traces formed by the depth electrodes according to the voltage difference.
The cost of the fracture stability evaluation system in the embodiment of the invention mainly lies in the construction of the detection borehole for installing the depth electrode, and in order to save cost, in a preferred embodiment, as shown in fig. 10, the monitoring station No. 1 in the embodiment comprises three depth electrodes a, B and c installed in the fracture and fracture zone below the bedrock surface, wherein the depth electrodes a and B are installed in the detection borehole a together, the installation depths of the depth electrodes a and B in the detection borehole a are different, the installation depths of the depth electrodes a and B and the depth electrode c installed in the detection borehole B are also different, and the depth electrodes a, B and c together form a plane parallel to the fracture surface of the fracture and fracture zone.
In other embodiments including more depth electrodes, more than one depth electrode may be disposed in multiple probe boreholes, or a greater number of depth electrodes may be disposed in multiple probe boreholes, according to the same principles, to improve detection accuracy.
Fig. 11 shows a monitoring station No. 1 according to another embodiment of the present invention, which is different from the previous embodiment in that the monitoring electrode c in this embodiment is a shallow electrode, the shallow electrode c is installed in a shallow soil layer in a fracture and fracture zone, the shallow electrode d has no installation depth requirement, and in some examples, the shallow electrode d is simply buried in the soil layer, but the electrode should be prevented from being exposed on the ground surface, and if isolation of artificial electromagnetic radiation is achieved, the monitoring station is better.
The superficial electrode c and the depth electrodes a and b respectively form two groups of monitoring channels, and the depth electrodes a and b form one group of monitoring channels, so that the superficial electrode c and the depth electrodes a and b form a plane parallel to a fracture surface of a fracture zone.
In this embodiment, the monitoring instrument is respectively connected to the depth electrodes a, b and the superficial electrode c, and detects a voltage difference between two monitoring electrodes in each group of monitoring channels formed by the depth electrodes a, b and the superficial electrode c, and sends the voltage difference to the local computing device. The local computing equipment performs interpolation of the equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels according to the interpolation method in the embodiment, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so as to draw out the equipotential lines of the electric field broken in the broken zone. The interpolation method is the same as the implementation method in the above embodiment, and therefore is not described in detail.
Based on the same principle as the fracture stability evaluation system in the above embodiment, the present invention further provides a fracture stability evaluation method, as shown in fig. 12, which is executed by the networked computing device in the above embodiment, and includes the following steps:
step S101: inputting a position parameter of a piezoelectric part and a preset size parameter of the piezoelectric part, which are acquired from networked computing equipment, into a fracture stability evaluation model;
the networked computing equipment acquires equipotential lines of a breaking electric field of a breaking broken belt, which are drawn by local computing equipment of each monitoring station in a plurality of monitoring stations, and determines the direction of a piezoelectric part of the breaking electric field detected by each monitoring station according to the equipotential lines of the breaking electric field of the breaking broken belt, which are drawn by the local computing equipment of each monitoring station; the direction of the piezoelectric part of the fracture electric field detected by each monitoring station is vertical to the equipotential line of the fracture electric field; each monitoring station includes: the system comprises at least three monitoring electrodes, a monitoring instrument and local computing equipment, wherein every two monitoring electrodes form a group of monitoring channels; the at least three electrodes are positioned on the same plane, the plane is parallel to the section of the fracture and fragmentation zone, and the at least two monitoring electrodes are used as depth electrodes and are arranged in the fracture and fragmentation zone below the bedrock surface through detection drill holes; every two monitoring electrodes are not positioned on the same horizontal plane at the same time, or the numerical value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of every monitoring electrode is consistent; the monitoring instrument is connected with each monitoring electrode, detects the electrical physical quantity difference between the two monitoring electrodes in each group of monitoring channels, and sends the electrical physical quantity difference to the local computing equipment; the local computing equipment interpolates the equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so that the equipotential lines of the breaking electric field in the breaking zone are drawn; the networking computing equipment determines the intersecting position of the piezoelectric position direction of each fracture electric field as the piezoelectric position of the fracture zone according to the piezoelectric position direction of the fracture electric field determined by each monitoring station;
step S102: and adjusting the size parameter of the preset piezoelectric part input into the model so that the difference of the electrophysical quantities of the at least three electrodes output by the fracture stability evaluation model approaches to the difference of the electrophysical quantities of the at least three electrodes detected by the monitoring instrument.
In an alternative embodiment, the number of depth electrodes per monitoring station is at least three and each depth electrode is installed in a fracture zone below the bedrock face by a different probe borehole.
In an optional embodiment, each two depth electrodes of each monitoring station form a group of monitoring channels, the monitoring instrument is connected with each depth electrode, and detects the difference of the electrical physical quantity between the two depth electrodes in each group of monitoring channels;
alternatively, the first and second electrodes may be,
every two depth electrodes of every monitoring station constitute a set of monitoring survey way, monitoring instrument and each depth electrode and one set up in the shallow electrode connection in the shallow soil layer of broken zone to detect the electrical physical quantity difference between every depth electrode and the shallow electrode, and obtain the electrical physical quantity difference between two depth electrodes in every group monitoring survey way that constitutes by the depth electrode according to the electrical physical quantity difference between every depth electrode and the shallow electrode.
In an alternative embodiment, the number of depth electrodes per monitoring station is at least three, and wherein at least two depth electrodes are installed in the fracture fragmentation zone below the bedrock face through the same probe borehole, the two monitoring electrodes being installed at different depths in the probe borehole.
In an alternative embodiment, the at least three monitoring electrodes of each monitoring station include a superficial electrode and two depth electrodes;
the shallow electrodes are installed in shallow soil layers of the fracture and fracture zone, and the two deep electrodes are installed in the fracture and fracture zone below the surface of the bedrock through different detection drill holes.
As for the method embodiment, since it is basically similar to the system embodiment described above, the description is simple, and the relevant points can be referred to the partial description of the system embodiment.
In the fracture stability evaluation system and method of the embodiment of the application, a plurality of monitoring stations and a networking computing device are arranged in an abnormal area of a fracture diffusion electric field, each monitoring station is provided with at least three monitoring electrodes in the fracture zone in parallel with the section of the fracture zone to form a plurality of groups of monitoring channels, a monitoring instrument detects the difference of electric physical quantities between two monitoring electrodes in each group of monitoring channels, a local computing device method interpolates the equal difference points of the electric physical quantities between the two monitoring electrodes in each group of monitoring channels so as to outline the equipotential lines of the fracture electric field strength of the fracture zone, each monitoring station can determine the direction of an electric field line because the equipotential lines are vertical to the electric field line, the networking device can determine the piezoelectric part of the fracture electric field, namely the position parameters of the piezoelectric part in the fracture zone according to a plurality of electric field line directions determined by the monitoring stations, and the position parameter and the size of the preset piezoelectric part are input into a fracture stability evaluation model, and the model parameter is continuously adjusted by comparing the simulation result with the actual monitoring data, so that the accuracy of fracture and fracture zone stability evaluation is improved.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (10)
1. An evaluation system for fracture stability, comprising:
a plurality of monitoring stations, a networked computing device, and an evaluation computing device, wherein each monitoring station comprises:
the system comprises at least three monitoring electrodes, a monitoring instrument and local computing equipment, wherein every two monitoring electrodes form a group of monitoring channels;
the at least three monitoring electrodes are positioned on the same plane, the plane is parallel to the section of the fracture and fragmentation zone, and the at least two monitoring electrodes are used as depth electrodes and are arranged in the fracture and fragmentation zone below the bedrock surface through detection drill holes;
every two monitoring electrodes are not positioned on the same horizontal plane at the same time, or the numerical value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of every monitoring electrode is consistent;
the monitoring instrument is connected with each monitoring electrode, detects the electrical physical quantity difference between the two monitoring electrodes in each group of monitoring channels, and sends the electrical physical quantity difference to the local computing equipment;
the local computing equipment performs interpolation of equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so that an equipotential line of a breaking electric field in a breaking zone is drawn, and the equipotential line is sent to the networked computing equipment;
the networked computing equipment determines the direction of the piezoelectric part of the fracture electric field detected by each monitoring station according to the equipotential lines of the fracture electric field in the fracture zone outlined by the local computing equipment of each monitoring station, wherein the direction of the piezoelectric part of the fracture electric field detected by each monitoring station is vertical to the equipotential lines of the fracture electric field; determining the intersecting position of the directions of the piezoelectric parts of the fracture electric fields as the piezoelectric part of the fracture zone according to the directions of the piezoelectric parts of the fracture electric fields detected by each monitoring station, and sending the position parameters of the piezoelectric part to the evaluation computing equipment;
the evaluation calculation equipment inputs the position parameter of the piezoelectric part and a preset piezoelectric part size parameter into a fracture stability evaluation model, and adjusts the preset piezoelectric part size parameter input into the fracture stability evaluation model, so that the difference of the electrophysical quantities of the at least three monitoring electrodes, which is simulated and output by the fracture stability evaluation model, approaches the difference of the electrophysical quantities of the at least three monitoring electrodes, which is detected by the monitoring instrument.
2. The system for evaluating fracture stability according to claim 1, wherein:
the number of depth electrodes per monitoring station is at least three and each depth electrode is installed in a fracture zone below the bedrock face by a different probe borehole.
3. The system for evaluating fracture stability according to claim 2, wherein:
every two depth electrodes of each monitoring station form a group of monitoring channels, the monitoring instrument is connected with each depth electrode, and the difference of the electrical physical quantity between the two depth electrodes in each group of monitoring channels is detected;
alternatively, the first and second electrodes may be,
every monitoring station still includes one and sets up the superficial electrode in the superficial soil layer in broken area, and every two degree of depth electrodes constitute a set of monitoring survey way, monitoring instrument is connected with every degree of depth electrode and superficial electrode to detect the electro-physical quantity difference between every degree of depth electrode and the superficial electrode, and obtain the electro-physical quantity difference between two degree of depth electrodes in every group monitoring survey way that constitutes by the degree of depth electrode according to the electro-physical quantity difference between every degree of depth electrode and the superficial electrode.
4. The system for evaluating fracture stability according to claim 1, wherein:
the number of the depth electrodes of each monitoring station is at least three, and at least two depth electrodes are installed in a fracture zone below the bedrock face through the same probe borehole, and the installation depths of the two depth electrodes in the probe borehole are different.
5. The system for evaluating fracture stability according to claim 1, wherein:
the at least three monitoring electrodes of each monitoring station comprise a superficial electrode and two depth electrodes;
the shallow electrodes are installed in shallow soil layers of the fracture and fracture zone, and the two deep electrodes are installed in the fracture and fracture zone below the surface of the bedrock through different detection drill holes.
6. A method for evaluating fracture stability, comprising the steps of:
inputting a position parameter of a piezoelectric part and a preset size parameter of the piezoelectric part, which are acquired from networked computing equipment, into a fracture stability evaluation model; the networked computing equipment acquires equipotential lines of a breaking electric field of a breaking broken belt, which are drawn by local computing equipment of each monitoring station in a plurality of monitoring stations, and determines the direction of a piezoelectric part of the breaking electric field detected by each monitoring station according to the equipotential lines of the breaking electric field of the breaking broken belt, which are drawn by the local computing equipment of each monitoring station; the direction of the piezoelectric part of the fracture electric field detected by each monitoring station is vertical to the equipotential line of the fracture electric field; each monitoring station includes: the system comprises at least three monitoring electrodes, a monitoring instrument and local computing equipment, wherein every two monitoring electrodes form a group of monitoring channels; the at least three monitoring electrodes are positioned on the same plane, the plane is parallel to the section of the fracture and fragmentation zone, and the at least two monitoring electrodes are used as depth electrodes and are arranged in the fracture and fragmentation zone below the bedrock surface through detection drill holes; every two monitoring electrodes are not positioned on the same horizontal plane at the same time, or the numerical value of the difference of the electrical physical quantities between every two monitoring electrodes is not zero, and the variation trend of the electrical physical quantities of every monitoring electrode is consistent; the monitoring instrument is connected with each monitoring electrode, detects the electrical physical quantity difference between the two monitoring electrodes in each group of monitoring channels, and sends the electrical physical quantity difference to the local computing equipment; the local computing equipment interpolates the equal difference points of the electro-physical quantities between the two monitoring electrodes in each group of monitoring channels by adopting an interpolation method according to the electro-physical quantity difference, and connects the equal difference points of the electro-physical quantities of different groups of monitoring channels by taking one monitoring electrode as a reference point, so that the equipotential lines of the breaking electric field in the breaking zone are drawn; the networked computing equipment determines the intersecting part of the directions of the piezoelectric parts of the fracture electric fields as the piezoelectric parts of the fracture zone according to the directions of the piezoelectric parts of the fracture electric fields detected by each monitoring station;
and adjusting the size parameter of the preset piezoelectric part input into the model so that the difference of the electrophysical quantities of the at least three monitoring electrodes output by the fracture stability evaluation model in a simulated manner approaches the difference of the electrophysical quantities of the at least three monitoring electrodes detected by the monitoring instrument.
7. The method for evaluating fracture stability according to claim 6, wherein:
the number of depth electrodes per monitoring station is at least three and each depth electrode is installed in a fracture zone below the bedrock face by a different probe borehole.
8. The method for evaluating fracture stability according to claim 7, wherein:
every two depth electrodes of each monitoring station form a group of monitoring channels, the monitoring instrument is connected with each depth electrode, and the difference of the electrical physical quantity between the two depth electrodes in each group of monitoring channels is detected;
alternatively, the first and second electrodes may be,
every two depth electrodes of every monitoring station constitute a set of monitoring survey way, monitoring instrument and each depth electrode and one set up the shallow electrode in the shallow soil layer in broken zone are connected to detect the electric physical quantity difference between every depth electrode and the shallow electrode to and obtain the electric physical quantity difference between two depth electrodes in every group monitoring survey way that constitutes by the depth electrode according to the electric physical quantity difference between every depth electrode and the shallow electrode.
9. The method for evaluating fracture stability according to claim 6, wherein:
the number of the depth electrodes of each monitoring station is at least three, and at least two depth electrodes are installed in a fracture zone below the bedrock face through the same probe borehole, and the installation depths of the two depth electrodes in the probe borehole are different.
10. The method for evaluating fracture stability according to claim 6, wherein:
the at least three monitoring electrodes of each monitoring station comprise a superficial electrode and two depth electrodes;
the shallow electrodes are installed in shallow soil layers of the fracture and fracture zone, and the two deep electrodes are installed in the fracture and fracture zone below the surface of the bedrock through different detection drill holes.
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