CN116006264A - Mine rock burst and water damage cooperative early warning method based on acoustic wave detection - Google Patents
Mine rock burst and water damage cooperative early warning method based on acoustic wave detection Download PDFInfo
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Abstract
The invention discloses a mine rock burst and water damage cooperative early warning method based on sound wave detection, which comprises the following steps: step 1, determining a layer position of a main water-bearing layer of coal mining, a region with stronger water-rich property and a rock stratum with impact tendency; step 2, calculating the development height of the rock burst key layer and the water guide fracture zone after coal mining by using a key layer theory; step 3, dividing a main aquifer and a sedimentary phase of the rock stratum with rock tendency; step 4, carrying out statistics and monitoring on static and dynamic data of coal mining; step 5, establishing a mine rock burst and water burst coupling risk evaluation system according to the result obtained in the step 4; step 6, constructing a mine rock burst and water burst coupling risk evaluation model based on a fuzzy weight-changing method based on the mine rock burst and water burst coupling risk evaluation system established in the step 5; and 7, verifying and correcting the risk evaluation model established in the step 6.
Description
Technical Field
The invention belongs to the technical field of coal mine safety, and particularly relates to a mine rock burst and water damage cooperative early warning method based on sound wave detection.
Background
Along with the acceleration of the western movement of the energy strategy in China, the development intensity of the coal resources of the shallow burial depth in the western part is gradually increased, the development of the coal resources is gradually transited to the deep part in recent years, the occurrence characteristics and the safe green efficient mining technology of the coal bed space are different from those of the shallow burial coal bed, the deposition environment of the water bearing layer of the top plate of the coal bed, the rock mechanical characteristics and the hydrogeological conditions are more and more complex,mine rock burst disasters are frequent, actual water inflow of a mine is far different from expected water inflow in an exploration stage, and according to incomplete statistics, the water inflow of ton coal exceeds 3m 3 . Disaster accidents not only threaten life safety of miners, but also cause great economic loss. The rock mechanical property, pore-throat distribution and connectivity of the sandstone of the roof of the coal bed, the development height of a water guide fracture zone after coal mining and the like are key core research objects for preventing and controlling rock burst and water bursting disaster of coal mining. Therefore, the development of the collaborative early warning of the rock burst and the water damage in the coal seam exploitation has important practical significance and great social significance for disaster prevention and control.
At present, the method for evaluating the water inrush risk of the mine roof mainly comprises a three-graph-double prediction method and an improved three-graph-double prediction method, wherein the three graphs in the three-graph-double prediction method comprise a water-rich partition graph of a water-filled aquifer of the coal seam roof, a roof burst safety partition graph and a roof water inrush condition comprehensive partition graph, and the improved three-graph-double prediction method adopts a analytic hierarchy process, a gray theory, a neural network algorithm and the like to fuse multi-source information. The impact risk evaluation method comprises a static evaluation method on a macroscopic level and a dynamic evaluation method based on real-time monitoring data, wherein the static evaluation method comprises a comprehensive index method, a rock burst possibility index diagnosis method and the like, and the dynamic evaluation method comprises a microseismic method, a ground sound method, a stress method, a vibration CT detection method, an electromagnetic radiation method and the like. The conventional risk evaluation method has the following problems:
(1) In the method of evaluating the roof water burst risk, the influence of the complex deposition environment of a deep mine is not considered in a roof water-rich partition map, and the situation that the development height of a water-guiding fracture zone of deep mine coal seam exploitation is fully communicated with a main aquifer is not considered in a roof water burst safety partition map, so that the roof water burst safety partition map cannot be compiled and drawn, and the roof water burst risk evaluation accuracy is affected.
(2) The mine impact risk evaluation microseism method is a microwave signal emitted by rock mass fracture, is an area monitoring method, only monitors rock mass damage, and cannot perform advanced early warning on a large event; the earth sound method is that the signal is uploaded to the well in a current mode, and the signal anti-interference capability is poor; the stress method can only monitor the stress increment, belongs to static point data monitoring, and the stress state of the coal rock is not a sufficient condition for determining the occurrence of rock burst, so that the early warning purpose can not be realized; the vibration CT detection method needs to excite and accept one lane, is suitable for detecting large-range areas such as stope face and the like, and cannot detect the tunneling face; the electromagnetic radiation method monitors and predicts rock burst according to the intensity of surrounding rock electromagnetic radiation, but the electromagnetic radiation of underground large-scale equipment often produces great interference on monitoring data, and the accuracy of the method can not meet the requirement of rock burst early warning.
(3) Because of different regional deposition environments, geological conditions, hydrogeological conditions, mining geological conditions, rock mechanical properties and the like, the factors influencing the impact mine pressure and roof water inrush are numerous, the influence mechanism is complex, and the risk of mutual offset between indexes possibly exists only by adopting a method for determining the weight of the dangerous evaluation index by using a hierarchical analysis method, an entropy weight method and the like.
(4) The rock burst and water damage risk evaluation methods at the present stage are both isolated rock burst disaster risk or water damage risk evaluation methods, and no coupling early warning method of the rock burst and the water damage risk evaluation methods is provided.
Disclosure of Invention
The invention aims to provide a mine rock burst and water damage cooperative early warning method based on sound wave detection, which is used for judging the rock burst and water damage dangers of coal bed rocks.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a mine rock burst and water damage cooperative early warning method based on sound wave detection is implemented according to the following steps:
the method is implemented according to the following steps:
dividing a sedimentary facies according to regional sedimentary background, lithology and logging information, and dividing a main aquifer and a sedimentary facies of a rock stratum with rock tendency according to a sedimentary facies dividing mark, a lithology mark, an ancient biologicals mark, a logging facies mark and the like on the basis of grasping regional sedimentary evolution history;
and 4, carrying out statistics and monitoring on static and dynamic data of coal mining, wherein: static data statistics and monitoring comprises the steps of obtaining acoustic wave detection, main aquifer thickness, sand-ground ratio, water guiding fracture zone development height, water enrichment and sedimentary facies static attitude information; dynamic data statistics and monitoring comprises microseismic monitoring, vibration CT monitoring, stress monitoring, ground sound monitoring and mine water inflow dynamic geochemical information;
and 7, verifying and correcting the risk evaluation model established in the step 6.
In the step 1, geological, hydrogeological, logging and rock mechanical property data including hydrological hole drilling columns, hydrological hole pumping experiment results, geological exploration reports, hydrogeological supplementary exploration reports, geophysical prospecting reports and impact tendency identification reports are collected, and main aquifers affecting coal seam exploitation are determined according to water-containing/water-resisting layer division and main hydrogeological features thereof and development conditions of water-guiding fracture zones of coal seam exploitation; determining a region with stronger water enrichment according to hydrogeologic features, well logging and geophysical prospecting interpretation results; the rock formation with the impact tendency is determined by referring to the relevant content of the impact tendency identification report.
As a preferred embodiment of the present invention, in the step 1, the main aqueous layer satisfies the following conditions: the thickness is larger; the water inflow of the drilling unit is large; and after the coal seam is mined, the development height of the water guiding fracture zone is partially or completely communicated with a main aquifer.
As a preferred technical solution of the present invention, in the step 1, the region with high water-rich property satisfies the following conditions: at the determined principal aquifer; the comprehensive display of the logging curve shows that the granularity of the rock is larger and the resistivity is smaller; and interpreting the water-rich abnormal region in the geophysical prospecting report.
As a preferable technical solution of the present invention, in the step 2, the determination of the rock burst key layer is calculated as follows:
step 2.1, determining the position of a hard rock stratum in the overburden from bottom to top;
assuming that the layer 1 rock stratum is a hard rock stratum, the layer 1 rock stratum is deformed with the layer 1 rock stratum until the layer m, but the layer m+1 is not deformed with the layer m, the layer 1 rock stratum is a layer 2 hard rock stratum; because the 1 st layer to the m th layer rock layers are in coordinated deformation, the curvatures of all the rock layers are the same, all the rock layers form a combined beam, and the load acting on the 1 st layer hard rock layer can be derived according to the combined beam principle:
wherein q is 1 (x) m To account for loading of the mth formation on the 1 st hard formation; h is a i 、γ i 、E i The thickness, bulk weight, elastic modulus (i=1, 2, …, m) of the ith formation, respectively; considering that the load formed by the m+1st layer on the 1 st hard rock layer is:
since the m+1 layer is a hard rock layer, the deflection of the m+1 layer is smaller than that of the lower rock layer, the lower rock layer is no longer needed to bear the load born by the upper rock layer, and the following steps are necessary:
q 1 (x) m+1 <q 1 (x) m (3)
substitution of formulas (1) and (2) into formula (3) and simplification can be obtained:
the formula (4) is a formula for judging the position of the hard rock stratum; when specific discrimination is carried out, calculating from the 1 st layer rock layer above the coal layer by layer, when
If the formula (4) is satisfied, the calculation is not performed; at this time, from the 1 st layer of rock layer upwards, the m th layer of rock layer is the 1 st layer of hard rock layer; starting from the 1 st hard rock layer, determining the position of the 2 nd hard rock layer according to the method, and so on until determining the uppermost hard rock layer (set as the n-th hard rock layer); and judging the position of the hard rock stratum to obtain the position of the hard rock stratum in the overburden rock and the controlled soft rock stratum group.
Step 2.2, calculating the breaking distance of each hard rock stratum;
according to the mechanical model of the clamped beam and the theoretical analysis of the material mechanics, the positive stress of any point in the beam is as follows:
wherein M is a section bending moment (KN.m) at which any point is located; y is the distance (m) between any point and the neutral axis of the cross section; h is the rock beam thickness (m);
analysis of the clamped beam shows that the maximum bending moment of the clamped beam occurs at two ends of the beam; namely:
the corresponding maximum tensile stress is:
when sigma is max ＝σ t When the rock beam breaks, the limit span is obtained by the formula (7):
step 2.3, comparing the breaking distance of each hard rock stratum according to the following principle to determine the position of the rock burst key layer;
if the k-th hard rock layer is a key layer, the breaking distance is smaller than that of all the hard rock layers on the upper part, namely, the requirements are satisfied
If the breaking distance L of the k-th hard rock layer k If the breaking distance of the (k+1) th hard rock layer is larger than the breaking distance of the (k+1) th hard rock layer, loading the (k+1) th hard rock layer on the (k) th hard rock layer, and recalculating the breaking distance of the (k) th hard rock layer;
discriminating L from the lowest hard rock layer by layer k <L k+1 Whether or not it is true, when L k >L k+1 The k-th hard formation fracture distance is recalculated.
In the step 2, the development height of the water-guiding fracture zone is determined as follows:
step 2.4, calculating the free space height of the lower part of the key layer and the soft rock layer;
calculating the free space height of the lower part of the key layer by the formula (10);
in the formula delta i Is the free space height below the i-th layer of rock; m is the coal seam mining thickness; h is a j The thickness of the j-th layer of rock stratum; k (k) j Residual crushing of rock of the j-th layerCoefficient of expansion.
Step 2.5, calculating the height of the water guide fracture zone;
the maximum deflection of the formation when the working surface is advanced to a distance where it can produce maximum tension is:
at this time, if the maximum deflection of the soft rock layer is greater than the height of the free space at the lower part of the soft rock layer, the soft rock layer will maintain a plastic state without being damaged due to the limitation of the free space, and the water guiding fracture zone does not develop upwards so far; then, there are:
ω i,max >Δ i (12)
conversely, when the maximum deflection of the soft rock layer is smaller than the height of the free space at the lower part, the soft rock layer is broken and is used for guiding water, and then:
ω i,max <Δ i (13)
the beneficial effects of the invention are as follows: (1) According to the mine rock burst and water disaster collaborative early warning method based on sound wave detection, a sound wave detection technology is introduced for the first time to monitor an overpressure zone and a water-rich abnormal zone of a roof overlying strata of coal mining, technical data is provided for mine rock burst and water bursting disaster early warning, disaster early warning accuracy is improved, disaster accidents are reduced, and disaster prevention and control cost is reduced; (2) According to the mine rock burst and water damage collaborative early warning method based on sound wave detection, microseismic monitoring data are used for monitoring high-energy events of rock burst and monitoring development heights of water guide fracture zones of coal seam exploitation, dynamic monitoring and static monitoring data are fused, and comprehensive basic theoretical data are provided for disaster early warning index system establishment; (3) According to the mine rock burst and water damage collaborative early warning method based on sound wave detection, the risk that rock burst and water burst risk evaluation indexes are mutually counteracted is avoided by adopting a fuzzy weight-changing method; (4) The mine rock burst and water disaster cooperative early warning method based on sound wave detection couples two disaster early warning modes of mine rock burst and water bursting, and has a powerful disaster early warning function compared with the traditional single mine (impact mine pressure or water bursting) disaster early warning mode.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of an acoustic detection overpressure zone;
FIG. 3 is a schematic cross-sectional view of an acoustic detection overpressure zone and a rich anomaly;
FIG. 4 is a system for evaluating the risk of coupling of mine rock burst and water damage.
In the figure: 1 is a coal seam; 2 is a drilling site; 3, directional drilling a main hole; 4 is directional drilling branch holes; 5. 7 is a water-rich abnormal area; 6 is the main aquifer/hard formation with impact propensity.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings and the specific embodiments.
As shown in FIG. 1, the mine rock burst and water damage cooperative early warning method based on sound wave detection comprises the following steps:
step 1: and determining the layer position of the main water bearing layer of coal mining, the region with stronger water-rich property and the rock stratum with impact tendency.
And (3) collecting geology, hydrogeology, well logging and rock mechanical property data in a carbon resource exploration stage, wherein the data comprise hydrohole drilling columns (including logging curves), hydrohole pumping experiment results, geological exploration reports, hydrogeology supplementary exploration reports, geophysical prospecting reports, impact tendency identification reports and the like, determining main aquifers influencing coal seam exploitation according to water-containing layer division and main hydrogeology characteristics thereof, development conditions of water-guiding fracture zones of coal seam exploitation and the like, determining areas with stronger water enrichment according to the hydrogeology characteristics, well logging and geophysical prospecting interpretation results, and determining rock stratum with impact tendency according to relevant contents of the impact tendency identification reports.
The main aquifer satisfies the following conditions: (1) the thickness of the main aquifer is large; (2) the drilling unit water inflow of the main aquifer is large; (3) And after the coal seam is mined, the development height of the water guiding fracture zone is partially or completely communicated with a main aquifer.
The region with higher water enrichment satisfies the following conditions: (1) at the identified principal aquifer; (2) The comprehensive display of the logging curve shows that the granularity of the rock is larger and the resistivity is smaller; and (3) interpreting the water-rich abnormal region in the geophysical prospecting report.
Step 2: and calculating the development height of the water-guiding fracture zone after mining the rock burst key layer and the coal seam by utilizing a key layer theory, and determining the development height of the water-guiding fracture zone by combining numerical simulation, physical simulation, field actual measurement and other means.
The rock burst key layer was judged as follows:
and 2.1, determining the position of the hard rock stratum in the overburden from bottom to top. Assuming that the 1 st layer is a hard layer, up to the m-th layer deforms in coordination therewith, and the m+1-th layer does not deform in coordination therewith, the m+1-th layer is the 2 nd hard layer. Because the 1 st layer to the m th layer rock layers are in coordinated deformation, the curvatures of all the rock layers are the same, all the rock layers form a combined beam, and the load acting on the 1 st layer hard rock layer can be derived according to the combined beam principle:
wherein q is 1 (x) m To account for loading of the mth formation on the 1 st hard formation; h is a i 、γ i 、E i The thickness, bulk weight, and elastic modulus (i=1, 2, …, m) of the ith formation, respectively. Considering that the load formed by the m+1st layer on the 1 st hard rock layer is:
since the m+1 layer is a hard rock layer, the deflection of the m+1 layer is smaller than that of the lower rock layer, the lower rock layer is no longer needed to bear the load born by the upper rock layer, and the following steps are necessary:
q 1 (x) m+1 <q 1 (x) m (3)
substitution of formulas (1) and (2) into formula (3) and simplification can be obtained:
equation (4) is a formula for determining the position of the hard rock layer. When specific discrimination is carried out, calculating from the 1 st layer rock layer above the coal layer by layer, when
If the expression (4) is satisfied, the calculation is not performed. At this time, from the 1 st layer of rock layer upwards, the m-th layer of rock layer is the 1 st layer of hard rock layer. Starting from the 1 st hard formation, the position of the 2 nd hard formation is determined as described above, and so on until the uppermost hard formation (set as the n-th hard formation) is determined. And judging the position of the hard rock stratum to obtain the position of the hard rock stratum in the overburden rock and the controlled soft rock stratum group.
And 2.2, calculating the breaking distance of each hard rock stratum.
According to the mechanical model of the clamped beam and the theoretical analysis of the material mechanics, the positive stress of any point in the beam is as follows:
wherein M is a section bending moment (KN.m) at which any point is located; y is the distance (m) between any point and the neutral axis of the cross section; h is the rock beam thickness (m).
From an analysis of the clamped beams, the maximum bending moment of the clamped beams occurs at both ends of the beams. Namely:
the corresponding maximum tensile stress is:
when sigma is max ＝σ t When the rock beam breaks, the limit span (breaking distance) is obtained by the formula (7):
in the formula, h k Thickness (m) of the kth hard rock layer; sigma (sigma) k Tensile strength (MPa) for the kth hard formation; q k Load (kN/m) to be applied to the kth hard rock layer 2 )。
From the formula (1), q k Can be determined as follows:
wherein the subscript k represents a kth hard formation; subscript j represents the number of the layer of the soft rock group controlled by the kth hard rock layer; m is m k Controlling the layer number of the soft rock stratum for the kth hard rock stratum; e (E) k,j ，h k,j ，γ k,j The elastic modulus, the layering thickness and the volume weight of a j-th layer rock layer in a soft rock layer group controlled by a k-th layer hard rock layer are respectively.
When j=0, it is the mechanical parameter of the hard rock. For example E 1,0 ，h 1,0 ，γ 1,0 Elastic modulus, thickness and volume weight of the 1 st layer hard rock layer, E 1,1 ，h 1,1 ，γ 1,1 The elastic modulus, the thickness and the volume weight of the 1 st soft rock in the soft layer group controlled by the 1 st hard rock layer are respectively.
Since the elastic modulus of the overburden layer can be regarded as 0, and the overburden layer thickness is H and the volume weight is γ, the load on the uppermost hard rock layer, i.e., the nth hard rock layer can be calculated as follows:
and 2.3, comparing the breaking distances of all hard rock layers according to the following principles to determine the positions of key layers:
(1) if the k-th hard rock layer is a key layer, the breaking distance is smaller than that of all the hard rock layers on the upper part, namely, the requirements are satisfied
(2) If the breaking distance L of the k-th hard rock layer k And if the fracture distance of the k+1 layer of hard rock stratum is larger than the fracture distance of the k+1 layer of hard rock stratum, loading the k+1 layer of hard rock stratum onto the k layer of hard rock stratum, and recalculating the fracture distance of the k layer of hard rock stratum.
(3) Discriminating L from the lowest hard rock layer by layer k <L k+1 Whether or not it is true, when L k >L k+1 The k-th hard formation fracture distance is recalculated.
The development height of the water-guiding fracture zone is determined as follows:
on the basis of judging the key layer, the maximum deflection of the soft rock layer and the lower free space height of the soft rock layer are judged by calculating the free space heights of the key layer and the lower free space of the soft rock layer, and the development height of the water-guiding fracture zone is judged, so that the development height of the water-guiding fracture zone is further and more accurately determined by combining numerical simulation, physical simulation, field actual measurement and other means.
Step 2.4, calculating the free space height of the lower part of the key layer and the soft rock layer:
assuming that only rock strata within the range of the water-guiding fracture zone generate crushing expansion, the free space is continuously reduced due to the crushing expansion of the rock, when the working face is pushed to a certain extent, the overlying rock strata subsides to be in contact with the collapsed gangue and gradually compact, and finally the crushing expansion of the collapsed gangue tends to residual crushing expansion coefficient. It is believed that only the formation within the zones of the riser and fracture will experience swelling, and the zone of subsidence thereon will not undergo a change in volume. The critical layer lower free space height is calculated from equation (12).
In the formula delta i Is the free space height below the i-th layer of rock; m is the coal seam mining thickness; h is a j The thickness of the j-th layer of rock stratum; k (k) j Is the residual coefficient of expansion of the j-th layer of rock.
Step 2.5, calculating the height of the water diversion fracture zone:
it is generally recognized that hard formations (referred to herein primarily as critical layers) do not have flexibility, while soft formations have flexibility. When the working surface is long enough, the lower part of the hard rock layer has free space height, so that the hard rock layer can be broken along the direction of the layer surface and water is guided, otherwise, the hard rock layer cannot be broken; in the case of soft rock formations, however, only plastic changes may occur due to the flexibility, in which case water is not conducted. Whether the plastic change can be developed into the fracture of the rock stratum or not is also to see whether the height of the free space at the lower part of the soft rock stratum is larger than the allowable sedimentation value (maximum deflection) for keeping the plastic state, and a specific judgment formula is given below.
The maximum deflection of the formation when the working surface is advanced to a distance where it can produce maximum tension is:
at this time, if the maximum deflection of the soft rock layer is greater than the height of the free space at the lower part thereof, the soft rock layer will remain in a plastic state without being damaged due to the limitation of the free space, and the water-guiding fracture zone will not be developed up to this point. Then, there are:
conversely, when the maximum deflection of the soft rock layer is smaller than the height of the free space at the lower part of the soft rock layer, the soft rock layer is broken and water is guided. Then, there are:
step 3: and dividing the sedimentary facies according to the regional sedimentary background, lithology and logging data.
On the basis of grasping the deposition evolution history of the region, the deposition phases of the main water-bearing layer and the rock stratum 6 with rock tendency are divided according to the deposition phase division marks, the lithology marks, the logging phase marks and the like.
The lithology mark mainly comprises colors, rock types, combinations, structures and structures, the logging phase analysis mainly comprises the steps of comprehensively analyzing the granularity change trend, the heterogeneity, the rhythm and the like of a sediment layer according to the natural gamma, the natural potential and the hidden information of the curve of the natural potential and combining parameters such as acoustic wave time difference, three-side resistivity, short source distance gamma and the like, so that the hydrodynamic condition and the sediment environment are indirectly judged, different sediment environments often have different logging curve morphological characteristics, and the logging curve morphological characteristics of different sediment environments are formed by combining a plurality of basic types.
Step four: and (5) carrying out statistics and monitoring on static and dynamic data of coal seam exploitation.
And constructing a downhole directional drill in a region with strong impact-prone stratum water-rich property on the coal seam 1 exploitation, and utilizing a sound wave detection technology to detect an overpressure zone and a porosity increase region, wherein the directional drill main hole 3 is constructed until a first layer of region 5 with strong impact-prone stratum water-rich property is covered on the coal seam, and continuing to construct a branch hole 4 until a second layer of region 7 with strong impact-prone stratum water-rich property.
Basic principle of acoustic wave detection: normally, as the depth of burial increases, the compaction of the mudstone formation increases, the fluid in the pores is removed and decreases, and the sonic velocity of the formation increases gradually. In certain special constructions and deposition environments, some mudstone layers contain too much pore water due to the too fast settling and the low compaction. At this point, the pressure of the mudstone pore water will not be just the hydrostatic pressure, but will bear a portion of the overburden pressure. This pressure will be transferred to the reservoir covered by it, creating an overpressure reservoir. The prediction of the overpressure reservoir is of great significance to drilling engineering and geological research. The sonic velocity of the formation may reflect changes in compaction and porosity of the formation, so that an overpressure zone may be found using sonic velocity logging. Normally, the trend of the mudstone sonic velocity increases with increasing depth. When an overpressure formation occurs, the velocity change will deviate from the normal trend, as shown in fig. 2. In different areas, the overpressure amplitude can be estimated from the deviation degree of the actual measurement time difference value and the normal time difference value according to experience.
Stress and ground sound monitoring points are distributed on the coal seam mining working face, and vibration of surrounding rock stress, high frequency and low energy is developed. Stress monitoring points are arranged in argillaceous siltstone, mudstone and siltstone with the vertical height of the working face top plate of 3-8 m; ground sound monitoring points are arranged in the working face influence range, ground sound probes must ensure that ground sound signals of a monitoring area can be received, geological breaking areas which interfere elastic wave propagation cannot exist between a mounting point and the monitoring area, each monitoring area is provided with at least 2 ground sound probes, the distance between each probe and the working face is determined according to the length of the working face, the common distance is 20-200 m, and the probes are far away from noise sources as far as possible when the working face condition allows.
An advanced microseismic monitoring system is adopted to monitor low-frequency vibration of a coal seam roof less than 200Hz, and the microseismic monitoring system consists of a sensor, a data acquisition system, a communication device, a time synchronization device, a server and data processing interpretation software. Monitoring stations are respectively arranged on the ground and underground, at least 4 detectors are guaranteed to receive vibration information of the area, the distance between the detectors is determined according to the size of a working face, and the smaller the distance is, the higher the positioning accuracy is. The detectors are arranged in a space three-dimensional mode, and have a certain fall in the vertical direction. The position, the energy and the like where vibration occurs are monitored through a microseismic system, so that a foundation is provided for rock burst risk analysis on one hand, and a basis is provided for determination of the development height of a water-guiding fracture zone of a coal seam on the other hand.
The vibration CT monitoring system monitors vibration waves of the working surface and consists of a ground wireless or ground optical transceiver, an underground monitoring substation and a vibration pickup sensor. A blasting point is arranged in a roadway on one side of a working surface or a manual vibration source is used for manually exciting the vibration source, a vibration pickup sensor is arranged in the roadway on the other side for receiving vibration waves, and the positive correlation between the wave velocity and the stress is determined according to the distance between the blasting point and the vibration pickup sensor and the vibration wave velocity distribution in the range of the vibration wave travel time inversion working surface received by the vibration pickup sensor, so that a high-impact dangerous area is divided.
The mine water inflow monitoring data are mainly obtained by adopting a buoy method, a weir measuring method, a volumetric method, a water level observation method and the like.
Step 5: and establishing a mine rock burst and water burst coupling risk evaluation system. According to the main control factors influencing rock burst and water burst, a risk evaluation system which is shown in fig. 4 and is fused with indexes such as static monitoring, dynamic monitoring and geochemical information is established.
Step 6: and constructing a mine rock burst and water burst coupling risk evaluation model based on a fuzzy weight-changing method. In order to avoid the mutual offset between indexes influencing rock burst and water burst, important indexes are covered by general important indexes, the invention provides a fuzzy weighting method for determining the weights of all indexes, so that the effect of the important indexes in risk evaluation is highlighted as much as possible, the accuracy of a risk evaluation model is improved, and after the weights of all evaluation indexes are determined, all indexes are superimposed by using a geographic information composite superposition method to finish risk early warning.
Step 7: and verifying and correcting the dangerous evaluation model by using the water inflow amount of the mine, the conventional rock burst occurrence cases and the like. Collecting mine water inflow in an area, data of rock burst accident data, drilling unit water inflow and the like of the area or the periphery similar to geology and mining conditions, further verifying and correcting a risk evaluation model, determining a threshold value of early warning sent by each index, and applying the corrected risk evaluation model to early warning of the rock burst and water burst coupling disasters in an unexplored area. The dangerous evaluation model is optimized and adjusted at any time according to the monitoring data and the change of geological exploration degree, so that technical support is provided for mine rock burst prevention and water damage prevention and control, and mine safe and efficient exploitation is ensured.
Application example:
the method comprises the following steps of mining a No. 3 coal bed of a coal mine, wherein the thickness of the coal bed is 6m, the burial depth is 610m, the coal bed is covered with a sandstone aquifer of a delay group, a straight-line group and a stable group, impact tendency reports show that the bottom of the aquifer of a roof board of the coal bed is straight Luo Zu, the impact tendency is provided, the working face is currently mined 12301, the trend of the working face is 300m, the trend of the working face is 1500m, a mine rock burst and water damage collaborative early warning model is constructed according to the following steps, and the safe mining of the working face under other similar conditions of the mine is scientifically guided.
Step 1: the coal seam 1 is determined to mine the main aquifer and the areas 5, 7 with strong water enrichment with the impact prone rock formation 6. And collecting geology, hydrogeology, well logging and rock mechanical property data in a carbon resource exploration stage, wherein the data comprise hydrohole drilling columns (including logging curves), hydrohole pumping experiment results, geological exploration reports, hydrogeology supplementary exploration reports, geophysical prospecting reports, impact tendency identification reports and the like, a main aquifer 6 influencing coal seam exploitation is determined according to water-containing (water-resisting) layer division and main hydrogeology characteristics thereof, development conditions of a water-guiding fracture zone of coal seam exploitation and the like, and areas 5 and 7 with stronger water enrichment are determined according to the hydrogeology characteristics, well logging and geophysical prospecting results, the stratum with impact tendency is a No. 3 coal seam roof straight-set aquifer 6, and the impact tendency index is 120kJ and is a stratum with strong impact tendency.
The main aquifer satisfies the following conditions: (1) The thickness of the water-bearing layer of the coal seam roof delay-installation group is 80-120 m, the thickness of the water-bearing layer of the straight-line group is 180-200 m, the thickness of the water-bearing layer of the stable group is 50-80 m, and the thickness of the water-bearing layer of the straight-line group is the largest; (2) The water inflow of the drilling unit of the water pumping test of the aquifer of the straight-flow group is 0.5-1.3L/(s.m), which is larger than that of the drilling unit of the aquifer of the Yan-an group and the stability group; (3) Coal seam mining fracture ratio 28 (empirical value), water guiding fracture zone development height 140m, and all areas are communicated with the main aquifer 6.
The region with higher water enrichment satisfies the following conditions: (1) in the identified primary aquifer 6; (2) The comprehensive display of 5 and 7 areas in the logging curve has larger granularity and smaller resistivity; (3) interpreting the water-rich abnormal areas 5 and 7 in the geophysical prospecting report.
Step 2: and calculating the development height of the water guide fracture zone after mining the rock burst key layer 6 and the coal seam to be 122.3m by utilizing a key layer theory, determining the development height of the water guide fracture zone to be 131.2m by combining numerical simulation, physical simulation, field actual measurement and other means, and determining the main layer position of the rock burst and the water burst disaster by combining the step one.
Step 3: and dividing the sedimentary facies according to the regional sedimentary background, lithology and logging data. On the basis of grasping the deposition evolution history of the region, the deposition phases of the main water-bearing layer and the rock stratum 6 with rock tendency are divided according to the deposition phase division marks, the lithology marks, the logging phase marks and the like. According to the dividing standard, the sediment phase of 6 is divided into sediment phases of a plait river, a curved flow river, a flood plain and the like, wherein 5 and 7 belong to the sediment phases of the plait river.
Step 4: and (5) carrying out statistics and monitoring on static and dynamic data of coal seam exploitation. Rock burst, water diversion fracture zone development height, water enrichment and the like are monitored on the working face 12301 of the coal seam 1 exploitation working face.
And constructing a downhole directional drill in a region 6 with strong impact-prone stratum water enrichment on the coal seam 1 exploitation, and utilizing a sound wave detection technology to detect the overpressure zone and the porosity increase regions 5 and 7, wherein the directional drill main hole 3 is constructed to cover a first layer of the region 5 with strong impact-prone stratum water enrichment on the coal seam, and continuing constructing the branch hole 4 to a second layer of the region 7 with strong impact-prone stratum water enrichment.
Stress and ground sound monitoring points are distributed on the coal seam mining working face, and vibration of surrounding rock stress, high frequency and low energy is developed. Stress monitoring points are arranged in siltstone with the vertical height of the top plate of the 12301 working face of 6m, and the spacing between the stress monitoring points is 100m; the ground sound monitoring points are distributed on the 12301 working face and staggered with the stress monitoring points, and 9 ground sound probes are respectively arranged on two roadways in the monitoring area, and the distance is 150m.
And an advanced microseismic monitoring system is adopted to monitor low-frequency vibration of the coal seam roof which is smaller than 200 Hz. Monitoring stations are respectively arranged on the ground and underground, 18 detectors are arranged to receive vibration information of the area, the distance between the detectors is determined according to the size of a working surface, and the distance between the detectors is generally 100m. The detectors are arranged in a space three-dimensional mode, and have a certain drop in the vertical direction, wherein the drop is 20m. And monitoring the position, energy and the like of vibration through a microseismic system, and determining that the communication range of the rock burst dangerous layer and the development height of the water guide fracture zone is mainly concentrated in 5 layers of 6 layers.
The vibration CT monitoring system monitors vibration waves of the working surface. An artificial seismic source is arranged in a roadway on one side of a working surface, a seismic pickup sensor is arranged in the roadway on the other side of the working surface to receive seismic waves, the distance between the seismic pickup sensors is 50m, the wave velocity distribution of the seismic waves is inverted, and a high-impact dangerous area is defined.
The mine water inflow monitoring data is mainly obtained by observing the water level of a water sump, the mining is carried out until the area is near 5, and the mine water inflow is obviously increased.
Step 5: and establishing a mine rock burst and water burst coupling risk evaluation system. According to the main control factors influencing rock burst and water burst, a risk evaluation system which is shown in fig. 4 and is fused with indexes such as static monitoring, dynamic monitoring and geochemical information is established.
Step 3: and constructing a mine rock burst and water burst coupling risk evaluation model based on a fuzzy weight-changing method. The weight of each evaluation index determined according to the fuzzy weight-changing method is respectively sound wave detection weight 0.15, stress monitoring weight 0.03, ground sound monitoring weight 0.05, main aquifer thickness weight 0.13, main aquifer sand-ground ratio 0.02, water-guiding fracture zone development height weight 0.12, water-rich weight 0.14, sedimentary facies weight 0.12, microseismic monitoring weight 0.16, vibration CT monitoring weight 0.05 and mine water inflow monitoring weight 0.03. And (3) fusing and superposing all the evaluation indexes according to the weights by using a geographic information composite superposition method to finish the mine rock burst and water burst coupling risk evaluation partition map.
Step 7: and verifying and correcting the dangerous evaluation model by using the water inflow amount of the mine, the conventional rock burst occurrence cases and the like. And further verifying and correcting the risk evaluation model according to the data of mine water inflow in the area, rock burst accident data generated by mines with similar geology and mining conditions, drilling unit water inflow and the like, and determining the threshold value of each index for giving out early warning. The determined risk evaluation model is applied to the rock burst and water burst coupling disaster early warning of the mine 12302 working face, and is optimized and adjusted at any time according to the monitoring data and the change of geological exploration degree, so that the application effect is good.
Claims (6)
1. A mine rock burst and water damage cooperative early warning method based on sound wave detection is characterized by comprising the following steps:
step 1, determining a layer position of a main water-bearing layer of coal mining, a region with stronger water-rich property and a rock stratum with impact tendency;
step 2, calculating the development height of the rock burst key layer and the water guide fracture zone after coal mining by using a key layer theory;
dividing a sedimentary facies according to regional sedimentary background, lithology and logging information, and dividing a main aquifer and a sedimentary facies of a rock stratum with rock tendency according to a sedimentary facies dividing mark, a lithology mark, an ancient biologicals mark, a logging facies mark and the like on the basis of grasping regional sedimentary evolution history;
and 4, carrying out statistics and monitoring on static and dynamic data of coal mining, wherein: static data statistics and monitoring comprises the steps of obtaining acoustic wave detection, main aquifer thickness, sand-ground ratio, water guiding fracture zone development height, water enrichment and sedimentary facies static attitude information; dynamic data statistics and monitoring comprises microseismic monitoring, vibration CT monitoring, stress monitoring, ground sound monitoring and mine water inflow dynamic geochemical information;
step 5, establishing a mine rock burst and water burst coupling risk evaluation system according to the result obtained in the step 4;
step 6, constructing a mine rock burst and water burst coupling risk evaluation model based on a fuzzy weight-changing method based on the mine rock burst and water burst coupling risk evaluation system established in the step 5;
and 7, verifying and correcting the risk evaluation model established in the step 6.
2. The method for collaborative early warning of mine rock burst and water damage based on acoustic detection according to claim 1, wherein in step 1, geological, hydrogeological, logging, and rock mechanical property data of carbon resource exploration stages are collected, including hydrohole drilling columns, hydrohole pumping experiment results, geological exploration reports, hydrogeological supplementary exploration reports, geophysical prospecting reports, and impact tendency identification reports, and main aquifers affecting coal seam exploitation are determined according to water/water-resistant layer division and main hydrogeological characteristics thereof, and development conditions of water-guiding fracture zones of coal seam exploitation; determining a region with stronger water enrichment according to hydrogeologic features, well logging and geophysical prospecting interpretation results; the rock formation with the impact tendency is determined by referring to the relevant content of the impact tendency identification report.
3. The method for collaborative early warning of mine rock burst and water damage based on acoustic detection according to claim 1, wherein in step 1, the main aquifer satisfies the following conditions: the thickness is larger; the water inflow of the drilling unit is large; and after the coal seam is mined, the development height of the water guiding fracture zone is partially or completely communicated with a main aquifer.
4. The mine rock burst and water damage collaborative early warning method based on acoustic wave detection according to claim 1, wherein in the step 1, a region with stronger water enrichment meets the following conditions: at the determined principal aquifer; the comprehensive display of the logging curve shows that the granularity of the rock is larger and the resistivity is smaller; and interpreting the water-rich abnormal region in the geophysical prospecting report.
5. The mine rock burst and water damage collaborative early warning method based on acoustic wave detection according to claim 1, wherein in the step 2, the judgment of calculating a rock burst key layer is as follows:
step 2.1, determining the position of a hard rock stratum in the overburden from bottom to top;
assuming that the layer 1 rock stratum is a hard rock stratum, the layer 1 rock stratum is deformed with the layer 1 rock stratum until the layer m, but the layer m+1 is not deformed with the layer m, the layer 1 rock stratum is a layer 2 hard rock stratum; because the 1 st layer to the m th layer rock layers are in coordinated deformation, the curvatures of all the rock layers are the same, all the rock layers form a combined beam, and the load acting on the 1 st layer hard rock layer can be derived according to the combined beam principle:
wherein q is 1 (x) m To account for loading of the mth formation on the 1 st hard formation; h is a i 、γ i 、E i The thickness, bulk weight, elastic modulus (i=1, 2, …, m) of the ith formation, respectively; considering that the load formed by the m+1st layer on the 1 st hard rock layer is:
since the m+1 layer is a hard rock layer, the deflection of the m+1 layer is smaller than that of the lower rock layer, the lower rock layer is no longer needed to bear the load born by the upper rock layer, and the following steps are necessary:
q 1 (x) m+1 <q 1 (x) m (3)
substitution of formulas (1) and (2) into formula (3) and simplification can be obtained:
the formula (4) is a formula for judging the position of the hard rock stratum; when specific discrimination is carried out, calculating from the 1 st layer rock layer above the coal layer by layer, when
If the formula (4) is satisfied, the calculation is not performed; at this time, from the 1 st layer of rock layer upwards, the m th layer of rock layer is the 1 st layer of hard rock layer; starting from the 1 st hard rock layer, determining the position of the 2 nd hard rock layer according to the method, and so on until determining the uppermost hard rock layer (set as the n-th hard rock layer); the position of the hard rock stratum in the overburden rock and the controlled soft rock layer group are obtained through judging the position of the hard rock stratum;
step 2.2, calculating the breaking distance of each hard rock stratum;
according to the mechanical model of the clamped beam and the theoretical analysis of the material mechanics, the positive stress of any point in the beam is as follows:
wherein M is a section bending moment (KN.m) at which any point is located; y is the distance (m) between any point and the neutral axis of the cross section; h is the rock beam thickness (m);
analysis of the clamped beam shows that the maximum bending moment of the clamped beam occurs at two ends of the beam; namely:
the corresponding maximum tensile stress is:
when sigma is max ＝σ t When the rock beam breaks, the limit span is obtained by the formula (7):
step 2.3, comparing the breaking distance of each hard rock stratum according to the following principle to determine the position of the rock burst key layer;
if the k-th hard rock layer is a key layer, the breaking distance is smaller than that of all the hard rock layers on the upper part, namely, the requirements are satisfied
L k <L k+1 (9)
If the breaking distance L of the k-th hard rock layer k Greater than the breaking distance of the (k+1) th hard rock layer above the (k+1) th hard rock layer, the load born by the (k+1) th hard rock layer is added to the (k) th hard rock layerRecalculating the breaking distance of the kth hard rock stratum on the rock stratum;
discriminating L from the lowest hard rock layer by layer k <L k+1 Whether or not it is true, when L k >L k+1 The k-th hard formation fracture distance is recalculated.
6. The method for collaborative early warning of mine rock burst and water damage based on acoustic wave detection according to claim 1, wherein in the step 2, the development height of the water-guiding fracture zone is determined as follows:
step 2.4, calculating the free space height of the lower part of the key layer and the soft rock layer;
calculating the free space height of the lower part of the key layer by the formula (10);
in the formula delta i Is the free space height below the i-th layer of rock; m is the coal seam mining thickness; h is a j The thickness of the j-th layer of rock stratum; k (k) j The residual crushing expansion coefficient of the j-th layer of rock;
step 2.5, calculating the height of the water guide fracture zone;
the maximum deflection of the formation when the working surface is advanced to a distance where it can produce maximum tension is:
at this time, if the maximum deflection of the soft rock layer is greater than the height of the free space at the lower part of the soft rock layer, the soft rock layer will maintain a plastic state without being damaged due to the limitation of the free space, and the water guiding fracture zone does not develop upwards so far; then, there are:
ω i,max >Δ i (12)
conversely, when the maximum deflection of the soft rock layer is smaller than the height of the free space at the lower part, the soft rock layer is broken and is used for guiding water, and then:
ω i,max <Δ i (13)。
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