阅读说明：本技术 一种基于冲击波激发震源的转换sh波探测冲刷带方法 (Method for converting SH wave detection washband based on shock wave excitation seismic source ) 是由 王勃 孙华超 刘盛东 李兴兴 龚震 王志丹 邢世雨 丁昕 张振东 张恒 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种基于冲击波激发震源的转换SH波探测冲刷带方法,通过在回采工作面进风巷的入口处、中间处以及切眼处分别施工钻孔,然后在每个钻孔内进行多次冲击波激发,从而产生三个共炮点道集组,然后建立坐标系后,通过对每个共炮点道集组提取存在转换SH波信号的地震记录进行分析,SH波是由Love型槽波转换形成,因此未遇到冲刷带前转换SH波能量弱,遇冲刷带后Love型槽波大量转换发育后使得转换SH波能量变强,因此利用转换SH波在不同时段的能量差异性进行成像；最终叠加后得出冲刷带的位置成像；为后续的安全生产提供技术指导。(The invention discloses a method for detecting a scour belt by converting SH waves based on a shock wave excitation seismic source, which comprises the steps of respectively constructing drill holes at an inlet, a middle part and a cutting hole of an air inlet roadway of a stope face, then carrying out multiple times of shock wave excitation in each drill hole to generate three common shot point channel set groups, then establishing a coordinate system, extracting seismic records with converted SH wave signals from each common shot point channel set group for analysis, wherein the SH waves are formed by Love-type channel wave conversion, so that the converted SH wave energy before encountering the scour belt is weak, and the converted SH wave energy becomes strong after encountering the scour belt and carrying out massive conversion development of Love-type channel waves, so that the energy difference of the converted SH waves in different time periods is utilized for imaging; finally, obtaining the position imaging of the scouring belt after superposition; provides technical guidance for subsequent safe production.)

1. A method for detecting a washout zone by converting SH waves based on a shock wave excitation seismic source is characterized by comprising the following specific steps:

the method comprises the following steps: respectively constructing a drill hole in the working face at an inlet, a middle part and a hole cutting part of an air inlet tunnel of the stope working face, wherein the length of the drill hole is N meters;

step two: respectively sending the three shock wave excitation seismic sources into the deepest parts of the three drill holes;

step three: the method comprises the following steps that m mounting holes are distributed in a return airway of a stope face, the distance between every two adjacent mounting holes is 5m, a detector is arranged in each mounting hole, and each detector is connected with a seismic recorder;

step four: selecting a drill hole at the position of the cut hole to excite firstly, exciting a shock wave excitation seismic source from the deepest position of the drill hole for the first time, and then exciting the shock wave excitation seismic source once every 5m of deviation from inside to outside to form a seismic source group which is divided intoIs other than S₁₁、S₁₂、S₁₃…S_1nReceiving seismic waves generated by each seismic source in real time by each detector and transmitting the seismic waves to a seismic recorder, wherein n common shot point gather formed by n seismic sources form a common shot point gather group;

step five: repeating the fourth step in the other two drill holes to respectively form other two seismic source groups S₂₁、S₂₂、S₂₃…S_2nAnd S₃₁、S₃₂、S₃₃…S_3nAnd two common shot gather groups are formed;

step six: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the coal seam inclination direction, the Y direction is the coal seam trend direction, the Z direction is the direction vertical to the coal seam, establishing the three-dimensional coordinate system by taking an air inlet roadway inlet as an original point, classifying the positions of each impact excitation seismic source and each detector into the three-dimensional coordinate system, and establishing a stope face transmission observation system;

step seven: selecting n shot-shared gather sets of one shot-shared gather set from three shot-shared gather sets for analysis, selecting seismic records in which flushing signals with converted SH waves exist, and selecting time windows t with converted SH waves from the seismic records₁，t₂，t₃…t_n；

Step eight: for the time window t obtained in the step seven₁，t₂，t₃…t_nRespectively carrying out energy calculation on the converted SH waves;

step nine: superposing the energy calculation results of the step eight to obtain an imaging result of the flushing belt in the working surface;

step ten: repeating the seventh step to the ninth step on the other two common shot point gather groups to obtain imaging results of the flushing zones in the other two working surfaces;

step eleven: and (4) superposing the three groups of imaging results obtained in the step nine and the step ten, wherein the overlapping range is the accurate range of the flushing belt of the working face.

2. The method for detecting the impulse bands of the converted SH waves based on the shockwave-excited seismic source of claim 1, wherein the specific energy calculation process in the step eight is as follows:

(1) at the seismic source S₁₁Formed shot-shared gather selection time window t₁The flushing belt with the inner period length converts the same-phase axis of the SH wave;

(2) the energy of the impulse band converted SH wave in-phase axis in different time periods is calculated, and the method comprises the following steps:

i, converting the relation between the energy of the SH wave and the energy attenuation coefficient and the propagation distance of the medium:

A＝A₀e^-βr

wherein A is₀Is the initial energy of the converted SH wave, a is the energy after propagation distance r, β is the attenuation coefficient;

in a transmission observation system of a stope working face, a certain angle theta exists between the particle vibration direction and the sensitive direction of the detector, the influence of the angle theta on the SH wave energy conversion is considered, and the formula is arranged as follows:

A＝A₀e^-βrsinθ

III, obtaining an attenuation coefficient β, and the steps are as follows:

A. gridding the three-dimensional coordinates, wherein the size of a grid is 1 m;

B. seismic source S₁₁Forming a ray with each detector, selecting one ray for solving, and enabling the attenuation coefficient of a medium in the grid through which the ray passes to be β₁，β₂，β₃…β_nThen, discretization thereof yields:

C. taking the logarithm of the two sides to obtain:

D. order:

E. then there is a matrix:

Br＝b

F. repeating the steps B to E to construct a matrix of m-1 other rays;

G. solving the m matrixes in the steps E and F to obtain the attenuation coefficients of the grids passed by all the rays in the common shot point gather group;

H. calculating the attenuation coefficient of the grid which does not pass through the ray in the working surface by using a kriging interpolation method, thereby forming the attenuation coefficients of all grids in the working surface area;

I. calculating the energy of the converted SH wave of all grids in the working surface area according to the attenuation coefficient;

IV, compared with the area without the scouring zone, the energy of the converted SH wave in the area of the scouring zone is obviously larger; the range of the energy value exceeding the threshold value P is the flushing zone area, and the method for obtaining the threshold value P is as follows:

A. discretizing the whole energy area to obtain k energy point values E_j(j＝1,2…k)；

B. The average value is calculated:

C. calculating the standard deviation:

D. the threshold value is: p-mean + standard deviation;

(3) repeating the steps (1) and (2) for n-1 common shot gather in the common shot gather group, and obtaining n-1 energy calculation results.

Technical Field

The invention relates to a method for detecting a washband in a working surface, in particular to a method for detecting the washband by converting SH waves based on a shock wave excitation seismic source.

Background

Due to the influence of geological conditions, the occurrence and the spreading condition of a coal bed are influenced to a certain extent by the flushing belt, and under the intelligent, efficient and accurate mining background, the back mining of a working face is seriously hindered by the flushing belt, so that the fine detection of the flushing belt is an urgent need for coal mine production.

At present, the main methods for detecting the washout zone in the working face of the coal seam include a geological rule method, a coal-rock mechanical parameter method, ground three-dimensional seismic exploration and the like, wherein the geological rule method and the coal-rock mechanical parameter method are limited by the workload of drilling and roadway detection, and the accuracy of detecting the washout zone is low due to high cost and long construction period of the drilling and the roadway detection and limited detection range of the 'diameter of a hole' of the drilling. The ground three-dimensional seismic exploration is influenced by complex terrain and shallow goafs, because the ground is far away from a target body, when the ground is away from the target body, most of seismic wave energy is reflected to the ground, only a small part of seismic wave energy is transmitted downwards, so that effective signal energy reflected to the ground in a later period is weaker, the difficulty in identifying effective waves is high, other interference waves exist, the difficulty in later processing is increased, the exploration precision of the scouring band in a working face is limited by the conventional method, and the scouring band detection method needs to be innovated urgently.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for detecting the washout zone by converting SH waves based on shock wave excitation seismic sources.

In order to achieve the purpose, the invention adopts the technical scheme that: a method for detecting a washout zone by converting SH waves based on a shock wave excitation seismic source comprises the following specific steps:

the method comprises the following steps: respectively constructing a drill hole in the working face at an inlet, a middle part and a hole cutting part of an air inlet tunnel of the stope working face, wherein the length of the drill hole is N meters;

step two: respectively sending the three shock wave excitation seismic sources into the deepest parts of the three drill holes;

step three: the method comprises the following steps that m mounting holes are distributed in a return airway of a stope face, the distance between every two adjacent mounting holes is 5m, a detector is arranged in each mounting hole, and each detector is connected with a seismic recorder;

step four: selecting a drill hole at the position of the cut hole to excite firstly, exciting a shock wave excitation seismic source from the deepest position of the drill hole for the first time, and then exciting the shock wave excitation seismic source once every 5m of deviation from inside to outside to form a seismic source group S₁₁、S₁₂、S₁₃…S_1nReceiving seismic waves generated by each seismic source in real time by each detector and transmitting the seismic waves to a seismic recorder, wherein n common shot point gather formed by n seismic sources form a common shot point gather group;

step five: repeating the fourth step in the other two drill holes to respectively form other two seismic source groups S₂₁、S₂₂、S₂₃…S_2nAnd S₃₁、S₃₂、S₃₃…S_3nAnd two common shot gather groups are formed;

step six: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the coal seam inclination direction, the Y direction is the coal seam trend direction, the Z direction is the direction vertical to the coal seam, establishing the three-dimensional coordinate system by taking an air inlet roadway inlet as an original point, classifying the positions of each impact excitation seismic source and each detector into the three-dimensional coordinate system, and establishing a stope face transmission observation system;

step seven: selecting n shot-shared gather sets of one shot-shared gather set from three shot-shared gather sets for analysis, selecting seismic records in which flushing signals with converted SH waves exist, and selecting time windows t with converted SH waves from the seismic records₁，t₂，t₃…t_n；

Step eight: for the time window t obtained in the step seven₁，t₂，t₃…t_nRespectively carrying out energy calculation on the converted SH waves;

step nine: superposing the energy calculation results of the step eight to obtain an imaging result of the flushing belt in the working surface;

step ten: repeating the seventh step to the ninth step on the other two common shot point gather groups to obtain imaging results of the flushing zones in the other two working surfaces;

step eleven: and (4) superposing the three groups of imaging results obtained in the step nine and the step ten, wherein the overlapping range is the accurate range of the flushing belt of the working face.

Further, the specific energy calculation process in the step eight is as follows:

(1) at the seismic source S₁₁Formed shot-shared gather selection time window t₁The flushing belt with the inner period length converts the same-phase axis of the SH wave;

(2) the energy of the impulse band converted SH wave in-phase axis in different time periods is calculated, and the method comprises the following steps:

i, converting the relation between the energy of the SH wave and the energy attenuation coefficient and the propagation distance of the medium:

A＝A₀e^-βr

wherein A is₀Is the initial energy of the converted SH wave, a is the energy after propagation distance r, β is the attenuation coefficient;

in a transmission observation system of a stope working face, a certain angle theta exists between the particle vibration direction and the sensitive direction of the detector, the influence of the angle theta on the SH wave energy conversion is considered, and the formula is arranged as follows:

A＝A₀e^-βrsinθ

III, obtaining an attenuation coefficient β, and the steps are as follows:

A. gridding the three-dimensional coordinates, wherein the size of a grid is 1 m;

B. seismic source S₁₁Forming a ray with each detector, selecting one ray for solving, and enabling the attenuation coefficient of a medium in the grid through which the ray passes to be β₁，β₂，β₃…β_nThen, discretization thereof yields:

C. taking the logarithm of the two sides to obtain:

D. order:

B＝[β₁β₂β₃…β_n]，r＝[r₁r₂r₃…r_n]^T；

E. then there is a matrix:

Br＝b

F. repeating the steps B to E to construct a matrix of m-1 other rays;

G. solving the m matrixes in the steps E and F to obtain the attenuation coefficients of the grids passed by all the rays in the common shot point gather group;

H. calculating the attenuation coefficient of the grid which does not pass through the ray in the working surface by using a kriging interpolation method, thereby forming the attenuation coefficients of all grids in the working surface area;

I. calculating the energy of the converted SH wave of all grids in the working surface area according to the attenuation coefficient;

IV, compared with the area without the scouring zone, the energy of the converted SH wave in the area of the scouring zone is obviously larger; the range of the energy value exceeding the threshold value P is the flushing zone area, and the method for obtaining the threshold value P is as follows:

A. discretizing the whole energy area to obtain k energy point values E_j(j＝1,2…k)；

B. The average value is calculated:

C. calculating the standard deviation:

D. the threshold value is: p-mean + standard deviation;

(3) repeating the steps (1) and (2) for n-1 common shot gather in the common shot gather group, and obtaining n-1 energy calculation results.

Compared with the prior art, the method comprises the steps of respectively constructing drill holes at an inlet, the middle and a cutting hole of an air inlet roadway of the stope face, then carrying out multiple times of shock wave excitation in each drill hole to generate three shot-point-shared gather groups, then extracting seismic records with converted transverse wave signals from each shot-point-shared gather group to carry out analysis imaging after a coordinate system is established, and finally superposing each imaging to obtain the position imaging of a scour zone; thereby providing data guidance for subsequent safe tunneling. The principle of detecting the washout band from the converted SH waves is: the inventor researches and discovers that the converted SH wave is formed by conversion of commonly developed Love channel waves, so that the energy of the converted SH wave is weak before encountering a flushing zone, and the energy of the converted SH wave is strengthened after the Love channel waves are converted and developed in a large amount after encountering the flushing zone, and when no flushing zone exists in a working surface, the converted SH wave does not develop in a large amount, so that the flushing zone can be detected according to the difference characteristic of the energy of the converted SH wave.

Drawings

FIG. 1 is a schematic view of the arrangement of the observation system in the present invention;

FIG. 2 is a diagram of numerical analog signals in the present invention;

FIG. 3 is a graph of a signal actually acquired using the present invention;

fig. 4 is an image of a print ribbon after use of the present invention.

In the figure: 1. shock wave excitation seismic source, 2, detector, 3, flushing band, 4, converted SH wave signal in wave field snapshot, 5, converted SH wave information in seismic record, 6, working face flushing band accurate range.

Detailed Description

The present invention will be further explained below.

As shown in the figure, the method comprises the following specific steps:

the method comprises the following steps: respectively constructing a drill hole in the working face at an inlet, a middle part and a hole cutting part of an air inlet tunnel of the stope working face, wherein the length of the drill hole is N meters;

step two: the three shock wave excitation seismic sources 1 are respectively sent to the deepest parts of the three drill holes;

step three: the method comprises the following steps that m mounting holes are distributed in a return airway of a stope face, the distance between every two adjacent mounting holes is 5m, a detector 2 is arranged in each mounting hole, and each detector 2 is connected with a seismic recorder;

step four: selecting a drill hole at the position of the cut hole to excite firstly, exciting the shock wave excitation seismic source 1 for the first time from the deepest part of the drill hole, and then exciting the shock wave excitation seismic source 1 for every 5m of deviation from inside to outside to form a seismic source group S₁₁、S₁₂、S₁₃…S_1nEach geophone 2 receives seismic waves generated by each seismic source in real time and transmits the seismic waves to a seismic recorder, and at the moment, n common shot point gather groups formed by n seismic sources form a common shot point gather group;

step five: repeating the fourth step in the other two drill holes to respectively form other two seismic source groups S₂₁、S₂₂、S₂₃…S_2nAnd S₃₁、S₃₂、S₃₃…S_3nAnd two common shot gather groups are formed;

step six: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the coal seam inclination direction, the Y direction is the coal seam trend direction, the Z direction is the direction vertical to the coal seam, establishing the three-dimensional coordinate system by taking an air inlet roadway inlet as an original point, and classifying the positions of each impact excitation seismic source 1 and each detector 2 into the three-dimensional coordinate system to establish a stope face transmission observation system;

step seven: selecting n shot-shared gather sets of one shot-shared gather set from three shot-shared gather sets for analysis, selecting seismic records in which flushing signals with converted SH waves exist, and selecting time windows t with converted SH waves from the seismic records₁，t₂，t₃…t_n；

Step eight: for the time window t obtained in the step seven₁，t₂，t₃…t_nRespectively carrying out energy calculation on the converted SH waves;

step nine: superposing the energy calculation results of the step eight to obtain an imaging result of the flushing belt in the working surface;

step ten: repeating the seventh step to the ninth step on the other two common shot point gather groups to obtain imaging results of the flushing zones in the other two working surfaces;

step eleven: and (4) superposing the three groups of imaging results obtained in the step nine and the step ten, wherein the overlapping range is the accurate range of the flushing belt of the working face.

Further, the specific energy calculation process in the step eight is as follows:

(1) at the seismic source S₁₁Formed shot-shared gather selection time window t₁The flushing belt with the inner period length converts the same-phase axis of the SH wave;

(2) the energy of the impulse band converted SH wave in-phase axis in different time periods is calculated, and the method comprises the following steps:

i, converting the relation between the energy of the SH wave and the energy attenuation coefficient and the propagation distance of the medium:

A＝A₀e^-βr

wherein A is₀Is the initial energy of the converted SH wave, a is the energy after propagation distance r, β is the attenuation coefficient;

in a transmission observation system of a stope working face, a certain angle theta exists between the particle vibration direction and the sensitive direction of the detector, the influence of the angle theta on the SH wave energy conversion is considered, and the formula is arranged as follows:

A＝A₀e^-βrsinθ

III, obtaining an attenuation coefficient β, and the steps are as follows:

A. gridding the three-dimensional coordinates, wherein the size of a grid is 1 m;

B. seismic source S₁₁Forming a ray with each detector, selecting one ray for solving, and enabling the attenuation coefficient of a medium in the grid through which the ray passes to be β₁，β₂，β₃…β_nThen, discretization thereof yields:

C. taking the logarithm of the two sides to obtain:

D. order:

B＝[β₁β₂β₃…β_n]，r＝[r₁r₂r₃…r_n]^T；

E. then there is a matrix:

Br＝b

F. repeating the steps B to E to construct a matrix of m-1 other rays;

G. solving the m matrixes in the steps E and F to obtain the attenuation coefficients of the grids passed by all the rays in the common shot point gather group;

H. calculating the attenuation coefficient of the grid which does not pass through the ray in the working surface by using a kriging interpolation method, thereby forming the attenuation coefficients of all grids in the working surface area;

I. calculating the energy of the converted SH wave of all grids in the working surface area according to the attenuation coefficient;

IV, compared with the area without the scouring zone, the energy of the converted SH wave in the area of the scouring zone is obviously larger; the range of the energy value exceeding the threshold value P is the flushing zone area, and the method for obtaining the threshold value P is as follows:

A. discretizing the whole energy area to obtain k energy point values E_j(j＝1,2…k)；

B. The average value is calculated:

C. calculating the standard deviation:

D. the threshold value is: p-mean + standard deviation;

(3) repeating the steps (1) and (2) for n-1 common shot gather in the common shot gather group, and obtaining n-1 energy calculation results.