CN110018062B - Method for positioning shearing failure position of rock structural surface in direct shear test - Google Patents

Method for positioning shearing failure position of rock structural surface in direct shear test Download PDF

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CN110018062B
CN110018062B CN201910373880.XA CN201910373880A CN110018062B CN 110018062 B CN110018062 B CN 110018062B CN 201910373880 A CN201910373880 A CN 201910373880A CN 110018062 B CN110018062 B CN 110018062B
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structural surface
arrival time
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CN110018062A (en
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江权
刘畅
晏飞
冯夏庭
徐鼎平
张家新
白国峰
乔志斌
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Wuhan Institute of Rock and Soil Mechanics of CAS
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Abstract

The invention discloses a method for positioning the shearing failure position of a rock structural surface in a direct shear test, which comprises the following steps: arranging acoustic emission sensors, establishing a txt format file according to the coordinates and the number k by the acoustic emission sensors arranged in the above way, and calculating a locking value Dt＝S/VsAnd synchronously carrying out structural surface test block shearing experiment and acoustic emission monitoring, recording acoustic emission signals by the emission sensors, outputting the arrival time of each elastic wave monitored by the six acoustic emission sensors, and using a locking value DtGrouping and sequencing the arrival time of the monitoring elastic waves, establishing an acoustic emission position adaptive value function according to the arrival time difference positioning principle, inputting the arrival time file of the elastic waves to be grouped and sequenced into the adaptive value function, calculating the optimal acoustic emission source position of the whole particle group, and screening out the coordinates of shear damage in the block space range on the structural plane. The method has high monitoring accuracy, eliminates the time when the interference influencing the precision reaches the elastic wave in advance, and can carry out acoustic emission positioning on the shearing damage position of the structural surface.

Description

Method for positioning shearing failure position of rock structural surface in direct shear test
Technical Field
The invention relates to a method for positioning a shearing failure position of a rock structural surface in a direct shear test, in particular to a method for positioning acoustic emission of the failure position in the shearing process of the rock structural surface, and belongs to the technical field of rock-soil mechanics.
Background
At present, with the rapid development of economic construction in China, more and more deep underground projects are built in China, and the projects are built in engineering rock masses. The engineering rock mass is composed of complete rock blocks and structural planes, the structural planes are mutually combined to cut the rock mass into rock blocks with different shapes and sizes, the structural planes have control effect on the mechanical properties of rocks, and the shear failure along the structural planes is the main failure mode of the engineering rock mass. The shearing failure process of the structural surface is very complex, and rock masses are mutually jointed and sheared in the shearing process, so that great obstruction is formed for researching the shearing failure of the structural surface. Therefore, the deep understanding of the shearing failure process is very important for the safety construction of geotechnical engineering, and the accurate grasping of the shearing failure process has important significance for preventing and treating the shearing failure.
The acoustic emission is a phenomenon that strain energy is quickly released to generate elastic waves due to deformation or damage inside a material, the released elastic waves can be picked up by an acoustic emission sensor, and the position of a fracture source can be located through the time difference of the elastic waves picked up by different sensors. Therefore, the acoustic emission is a nondestructive monitoring, and the whole process monitoring can be carried out on the material damage process on the premise of not influencing the material internal damage process. Rock is a typical brittle material, and elastic waves released when the rock is broken can be well picked up by an acoustic emission sensor, so acoustic emission monitoring is widely applied to monitoring of a rock destruction process.
However, due to the interference of structural surface shear failure on elastic wave propagation and the limitation of the traditional acoustic emission positioning algorithm on the sensor array, the existing structural surface shear failure acoustic emission positioning technology has the disadvantages of inaccurate positioning on the positioning result, complicated acoustic emission positioning process or non-convergence of the positioning result, thereby restricting the deep knowledge of the structural surface shear failure mechanism.
(1) In the shearing process of the structural surface, the upper blocks of the structural surface are tightly attached, and the existence of the structural surface generates great interference on the propagation of elastic waves, so that acoustic emission signals are distorted and inaccurate in positioning, and the shearing failure area of the structural surface cannot be truly reflected. In chapter 3.4, "influence of crack on ultrasonic wave propagation" in acoustic characteristics of rock-bearing concrete and applications thereof, authors, Zhao Ming dynasty mentioned that the linear dimension of a macroscopic crack in a rock mass is much larger than the wavelength of ultrasonic waves, and if the crack is open and unfilled, because the wave impedance contrast at the crack interface is large, sound waves cannot penetrate through the crack but only propagate around the crack, diffraction is generated at the crack, so that the sound wave energy is attenuated, and the wave speed is reduced. Therefore, due to the existence of the structural surface, in the shearing process of the structural surface, the structural surface is damaged to cause the distortion of the elastic wave, so that a large error exists when the acoustic emission sensor picks up the elastic wave. The acoustic emission positioning technology principle is based on sensor time difference positioning, and if errors occur in time difference picking, the positioning results are greatly influenced. In "computational engineering and science", volume 31, 4 of 2009, entitled "time difference calculation research in acoustic emission positioning", author liu wei dong, the paper states that for line positioning, assuming that the wave speed of a faster stress wave is twice the wave speed of a slower stress wave, the length of a monitoring interval in which the maximum positioning error of an acoustic emission source caused by abnormal wave time difference measurement deviation can reach 25% can be deduced. Chinese patent publication No. CN 102435980a, published japanese 2012.05.02, entitled "an acoustic emission source or micro seismic source positioning based on analytic solution", the application discloses that an acoustic emission source or micro seismic source positioning method obtained by an analytic solution method does not require iterative solution, but the method does not consider an elastic wave arrival time picking error caused by interference of elastic wave propagation due to a structural plane, so that the structural plane shear failure acoustic emission source positioning cannot be accurately performed.
(2) Some traditional acoustic emission monitoring and positioning methods require that an acoustic emission source is positioned in an acoustic emission sensor array, otherwise, a positioning result is not converged, and a positioning error is large. Due to the interference of the structure surface on the elastic wave, the sensor is surrounded by the shearing area, so that the time-of-arrival error is caused, and the shearing damage position of the structure surface cannot be accurately positioned and analyzed. Chinese patent publication No. CN106646375A published japanese 2017.05.10 entitled "a rock acoustic emission source positioning method based on ALL # FFT phase difference", which utilizes wavelets to perform acoustic emission denoising, calculates the phase difference of denoised acoustic emission signals by utilizing ALL-FFT phase difference, solves the phase difference, obtains the delay estimation of acoustic emission, and performs acoustic emission source coordinates in a reverse manner, but the invention is not suitable for the positioning situation when the acoustic emission source is outside the sensor array.
In the 2 nd stage 2019 of statistics and decision, entitled "particle swarm algorithm research with adaptive behavior" written by authors, the basic idea of the particle swarm algorithm is to simulate the bird predation process, each particle moves in a solution space, the optimal points searched by each particle and the global optimal points searched by all the particles are recorded, and the particle continuously updates the speed and the position of the particle according to the optimal points and the global optimal points. The particle swarm algorithm can well solve the multi-extreme nonlinear problem to obtain a global optimal solution, and the particle swarm algorithm is applied to the structural surface shear failure acoustic emission positioning method, so that the positioning precision can be improved.
Disclosure of Invention
Aiming at the existing problems, the invention aims to provide an acoustic emission positioning method for the structural surface shear failure position in a direct shear test, aiming at overcoming the interference of the structural surface shear failure on the elastic wave propagation and the inaccuracy of the conventional structural surface failure position positioning based on acoustic emission time, and realizing the accurate acoustic emission positioning monitoring on the structural surface shear failure position.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for positioning a shearing failure position of a rock structural surface in a direct shear test comprises the following steps:
s1: the method comprises the following steps of manufacturing a natural structural surface test block with mutually matched contact surfaces, dividing the structural surface test block into an upper structural surface block and a lower structural surface block which are equal in size from top to bottom, and arranging an acoustic emission sensor on the structural surface according to an acoustic emission sensor monitoring arrangement scheme, wherein the acoustic emission sensor monitoring arrangement scheme on the structural surface is as follows:
(1) six acoustic emission sensors are arranged on a structural surface to be monitored in a direct shear test, the acoustic emission sensors are distributed on the left side surface and the right side surface of a block test block on the structural surface along the shearing direction, and three acoustic emission sensors on each side surface form a unit column; the length of the upper block of the structural surface along the shearing direction is L, and the height of the upper block of the structural surface is H;
(2) the distances between the acoustic emission sensors of the odd-numbered sequence and the even-numbered sequence in the two unit rows and the top surface of the block on the structural surface are respectively different;
(3) the distances between the acoustic emission sensors positioned in the middle sequence in each unit row and the end surface on one side of the structural surface upper block are different, and the distances between the acoustic emission sensors positioned in the two end sequences and the end surfaces on the two sides of the structural surface upper block are equal;
s2, establishing a coordinate system in the structural surface upper block, and establishing a txt format file according to the coordinates and the number k by the acoustic emission sensors arranged in the above way;
s3, calculating the space distance S between two sensors with the farthest space distance in the acoustic emission sensors arranged in the mode, and measuring the wave velocity V of elastic waves on the structural surface by using a wave velocity detectorsObtaining a lockout value Dt＝S/Vs；
S4, a structural surface test block shearing experiment and acoustic emission monitoring are synchronously carried out, an acoustic emission system monitors the whole shearing experiment until the experiment is finished, acoustic emission signals are recorded through the emission sensors, the arrival time of each elastic wave monitored by the six acoustic emission sensors is output, and a locking value D is usedtGrouping and sequencing the arrival time of the monitoring elastic wave:
(R1) setting the arrival time t of the R-th elastic waverThe arrival time of the first elastic wave is added with a locking value DtWhen the locking is obtained, selecting the arrival time t of the r-th elastic waverArrival time t of all elastic waves in the period of time of arrival of the lockrForming a grouping sequence j;
(R2) arrival time t of elastic wave in packet sequencerIf the number is less than 4, the elastic waves are not subjected to packet sequencing, and the arrival time t of the elastic waves later than the last bit in the packet sequence isrSet as the arrival time of the first elastic wave, heavilyRepeating the previous step R1 to form a new grouping sequence j;
(R3) arrival time t of elastic wave in packet sequence RrIf the number is not less than 4, the arrival time t of the elastic waves in the packet sequence is determinedrAssigning a grouping number j;
(R4) setting the arrival time tr of the elastic wave later than the last bit in the grouping sequence of step R3 as the arrival time of the first elastic wave, repeating steps R1 to R3, and forming a new grouping sequence;
grouping all the elastic wave arrival times, inputting the serial number k of each acoustic emission sensor, the elastic wave arrival times acquired by each acoustic emission sensor and the group number sequence r into a txt text for storage.
S5, according to the arrival time difference positioning principle, establishing an acoustic emission position adaptive value function, and setting a kth sensor to calculate the arrival time as follows:
Figure BDA0002050954750000051
in the formula: t is the time of occurrence of the acoustic emission event, (x)k,yk,zk) (ii) is the kth sensor coordinate;
(x, y, z) is the location of the source of the acoustic emission event during the shearing of the structural plane; v is the equivalent speed of acoustic emission elastic wave propagating in the block on the structural surface; t received by the kth acoustic emission sensorkRepresenting the arrival time of the elastic wave;
the time difference between the two adjacent acoustic emission sensors k +1 and k is
Figure BDA0002050954750000061
In the formula:
Figure BDA0002050954750000062
Figure BDA0002050954750000063
function of adaptive value for distinguishing acoustic emission event position as
Figure BDA0002050954750000064
In the formula, △ WKThe difference between the times when the k +1 th acoustic emission sensor and the k-th acoustic emission sensor are monitored;
s6, initializing learning factor c of particle swarm positioning algorithm1、c2Group size N, positioning accuracy requirement ε0The parameters are that the acoustic emission event source coordinates, the initial elastic wave speed range and the flight algebra n are initially assigned in the block space range on the structural surface;
s7, inputting the coordinates txt file of the six acoustic emission sensors and all the elastic wave arrival time files in the jth grouping sequence into the adaptive value function of the step S5 according to the grouping sequence j, and calculating the adaptive value of each particle i in the jth grouping sequence in the step S5
Figure BDA0002050954750000065
S8, if
Figure BDA0002050954750000066
Then the output acoustic source coordinate X ═ X, y, z, defines the historically best acoustic source coordinate P for the ith particlei＝(Pi1,Pi2,Pi3) (x, y, z) in
Figure BDA0002050954750000067
Minimum value of medium
Figure BDA0002050954750000068
Obtaining an optimal acoustic emission source position P for the entire population of particlesg＝(Pg1,Pg2,Pg3) The calculation is finished;
otherwise, the particle position is updated by applying the particle position updating formula of the acoustic emission source, and the steps S7-S8 are repeated until the particle position is updated
Figure BDA0002050954750000071
Or the flight algebra n exceeds the limit, the calculation result P is outputg＝(Pg1,Pg2,Pg3) I.e., the coordinates of the shear failure;
s9, repeating the steps S7-S8 according to the arrival time t of the elastic wave in each grouping sequencerCalculating the coordinate of the shearing damage;
s10, screening out coordinates of shear failure in the space range of the upper block of the structural surface by combining the shear surface shear characteristics, projecting the coordinates of shear failure to the contact surface of the upper block of the structural surface and the lower block of the structural surface to obtain the coordinates of shear failure occurring on the structural surface, and drawing a structural surface shear failure graph.
Preferably, the acoustic emission source, i.e. the particle position update formula:
Figure BDA0002050954750000072
Figure BDA0002050954750000073
in the formula: (ii) a c. C1＝c2A learning factor greater than 2; r is1And r2Is between [0,1]A random number in between; vector Pi＝(Pi1,Pi2,Pi3) And Pg＝(Pg1,Pg2,Pg3) The optimal acoustic emission source coordinates searched for the ith particle so far and the optimal acoustic emission source coordinates searched for the entire particle so far, respectively;
Figure BDA0002050954750000074
is the compression factor.
Further, the adaptive value of each particle i in the j-th group component sequence in step S5 is calculated
Figure BDA0002050954750000075
Comprises the following steps: inputting arrival time of elastic waves monitored by all acoustic emission sensors in the jth group according to the group sequence j
Figure BDA0002050954750000076
File, calculate each groupTime-of-arrival differences Δ W between k acoustic emission sensors within sequence jk jThen, the arrival time difference Δ W is obtainedk jK acoustic emission sensor coordinates (x)k,yk,zk) Requirement epsilon for positioning precision of file and particle swarm0Substituting into step S5 to calculate the adaptive value of each particle i in the jth group according to the initial position of the particle group in step S6
Figure BDA0002050954750000077
Due to the adoption of the technical scheme, the invention improves the inaccuracy of acoustic emission positioning of the shearing failure position of the rock structural surface in the traditional direct shear experiment, and has the following advantages:
(1) the acoustic emission sensor elastic wave arrival time monitoring accuracy is high: by arranging the acoustic emission sensors on the structural surface, the adverse effect that the elastic waves of the upper and lower discs of the structural surface are inaccurate in arrival time due to the shear failure of the structural surface when the elastic waves penetrate through the structural surface is eliminated, and the arrival time of the acoustic emission elastic waves can be obtained more accurately when the structural surface is sheared and damaged.
(2) The acoustic emission sensor monitoring data processing effectiveness is high: the monitoring data of the acoustic emission sensors are grouped through the locking values, so that the invalid positioning data does not participate in the positioning process, and a compressed particle swarm positioning algorithm is adopted, so that the particle swarm searching speed is higher, and the real-time of a large number of acoustic emission sensors can be more effectively faced.
(3) The acoustic emission positioning of the shearing failure position of the structural surface is accurate: the acoustic emission positioning can be well carried out on the shearing failure position of the structural surface by combining the arrangement method of the blocks on which the sensors are all arranged on the structural surface with the particle swarm algorithm which can well solve the multi-extreme-value nonlinear problem.
Description of the drawings:
FIG. 1 is a top view of a bulk acoustic emission sensor arrangement on a structural plane;
FIG. 2 is a right side view of a block acoustic emission sensor arrangement on a structural plane;
FIG. 3 is a left side view of a bulk acoustic emission sensor arrangement on a structural plane;
FIG. 4 is a file of elastic wave arrival time ungrouped monitored by an acoustic emission sensor;
FIG. 5 is a time-of-arrival and sequence file of elastic waves monitored by an acoustic emission sensor;
FIG. 6 is a coordinate file of an acoustic emission sensor;
FIG. 7 is a result file of particle swarm calculation;
FIG. 8 is a cut-to-destroy coordinate file after screening;
FIG. 9 is an acoustic emission localization map of a structural surface shear failure location;
FIG. 10 is a top view of the arrangement of bulk acoustic emission sensors on a structural plane in a control experiment;
FIG. 11 is a right side view of the arrangement of bulk acoustic emission sensors on a structural plane in a control experiment;
FIG. 12 is a left side view of the placement of bulk acoustic emission sensors on a structural plane in a control experiment.
Specific example 1:
the method for locating the position of a block shear failure on a structural surface by using acoustic emission according to the present invention is described in further detail below with reference to fig. 1,2, 3, 4, 5, 6, 7 and 8.
The optimization method for positioning the block shearing failure position on the structural plane by adopting acoustic emission comprises the following steps:
(1) the test block 10 was processed into a rectangular parallelepiped block of 150 × 120 × 150mm, and as shown in fig. 2, the total two blocks of the test block were divided into an upper block 7 and a lower block 8, and the upper block 7 and the lower block 8 were combined to form a rectangular parallelepiped block of 150 × 120 × 150 mm. The contact surfaces of the upper block and the lower block are made to be close to natural structure surfaces and can be tightly attached.
(2) As fig. 1 shows a plan view of the upper block 7, six acoustic emission sensors (1, 2, 3, 4, 5, 6) are arranged on the structural surface to be detected in the block 7, all of which are arranged in the following manner:
on the left side and the right side of the structural surface upper block 7 along the shearing direction, a row of acoustic emission sensors with the same number is arranged on each side, and three acoustic emission sensors are arranged on each side along the edge length direction every 150mm to form a unit row. Specifically, as shown in fig. 1, a first acoustic emission sensor 1, a second acoustic emission sensor 2, and a third acoustic emission sensor 3 are sequentially distributed on the right side surface of a block 7 on a structural surface along a shearing direction, and a fourth acoustic emission sensor 4, a fifth acoustic emission sensor 5, and a sixth acoustic emission sensor 6 are sequentially distributed on the left side surface of the block 7 on the structural surface along the shearing direction;
the emission sensors are arranged on two sides of the structural surface upper block 7 in a staggered mode along the shearing direction according to two heights, the ratio of the distances between the acoustic emission sensors in odd-numbered sequences and even-numbered sequences in the two unit rows and the top surface of the structural surface upper block 7 is 1:3,
specifically, the first acoustic emission sensor 1, the third acoustic emission sensor 3 and the fifth acoustic emission sensor 5 in the odd-numbered sequence are positioned in the same horizontal plane, and the distance from the horizontal plane to the top of the structural surface upper block 7 is 18.75 mm; the second acoustic emission sensors 2, the fourth acoustic emission sensors 4 and the sixth acoustic emission sensors 6 in the even number sequence are positioned in the same horizontal plane, and the distance between the horizontal plane and the top of the block on the structural plane is 56.25 mm;
the distances between the acoustic emission sensors positioned in the middle sequence in each unit row and the end face on one side of the structural surface upper block 7 are different, the distances between the acoustic emission sensors positioned in the two end sequences and the end faces on the two sides of the structural surface upper block 7 are equal, and preferably, the distance ratio between the acoustic emission sensors positioned in the middle sequence in each unit row and the end faces on the two sides of the structural surface upper block 7 is 2:3 or 3: 2; specifically, the distance from the first acoustic emission sensor 1 to the front end of the structural surface upper block 7 is 15mm, the distance from the second acoustic emission sensor 2 to the front end 9 of the structural surface upper block 7 is 60mm, the distance from the fifth acoustic emission sensor 5 to the front end 9 of the structural surface upper block 7 is 90mm, and the distance from the third acoustic emission sensor 3 to the sixth acoustic emission sensor 6 to the front end 9 of the structural surface upper block 7 is 135 mm;
(3) the acoustic emission sensors arranged in the above manner are arranged in terms of coordinates (x)k,yk,zk) And number k creates a txt format file as in fig. 5.
(4) Calculating the space distance S between the two sensors with the farthest space distance in the acoustic emission sensors arranged in the above manner, such as the sixth acoustic emission sensor 6 and the first acoustic emission sensor 1 or the third acoustic emission sensor 6 and the fourth acoustic emission sensor 4, and measuring the knot by using a wave speed detectorThe wave velocity of the elastic wave on the structural surface is VsObtaining a lockout value Dt＝S/Vs；
Pressing the structural surface upper block 7 and the structural surface lower block 8 to form an experiment test block 10, placing the experiment test block 10 on an experiment machine, starting an acoustic emission monitoring system, loading a normal load on the experiment test block 10 at first to enable the structural surface upper block 7 and the structural surface lower block 8 to be in a tight pressing state, then loading a shear load on the experiment test block 10 until the experiment is finished, recording an acoustic emission signal through the emission sensor, and monitoring the arrival time t of each elastic wave monitored by six acoustic emission sensorsrAnd inputting the acoustic emission signals into a txt text, and storing the acoustic emission signals in sequence according to the serial number k of each acoustic emission sensor and the sequence r of the arrival time of the elastic waves collected by each acoustic emission sensor, as shown in FIG. 4.
The wave speed of a block on a structural surface is 2000m/s measured by using an elastic wave speed measuring instrument, and the sensor arrangement scheme is that the spatial distance between two sensors with the farthest spatial distance is 173.8mm, and then the latching value D is obtainedt0.000869 s. Using the lock value to the elastic wave arrival time trtxt text is grouped:
r1, setting the arrival time t of the r-th elastic waverThe arrival time of the first elastic wave is added with a locking value DtWhen the locking is obtained, selecting the arrival time t of the r-th elastic waverArrival time t of all elastic waves in the period of time of arrival of the lockrForming a packet sequence;
r2. arrival time t of elastic wave in packet sequencerIf the number is less than 4, the elastic waves are not subjected to packet sequencing, and the arrival time t of the elastic waves later than the last bit in the packet sequence isrSetting the arrival time of the first elastic wave, and repeating the previous step R1 to form a new grouping sequence j;
r3. arrival time t of elastic wave in packet sequence jrIf the number is not less than 4, the arrival time t of the elastic waves in the packet sequence is determinedrAssigning a grouping number j;
r4. will be later than the elastic wave of the last bit in the sequence of packets of step R3 by the arrival time trSetting the arrival time of the first elastic wave, repeating the steps R1-R3 to formA new sequence of packets.
Obtaining the updated arrival time t of the elastic wave as shown in FIG. 5rTxt text is grouped.
In this step, a lock value D is sett＝S/VsThe meaning of (1) is: when the structural surface upper block 7 and the structural surface lower block 8 are sheared, a plurality of shearing points are arranged, the time for damaging each shearing point is inconsistent and randomly distributed, different shearing points can be damaged simultaneously or successively, the arrival time of the elastic wave detected in the locking value can be approximately regarded as the acoustic emission signal generated by damaging the same shearing point, and the problem of large positioning result error caused by measuring the coordinates of the shearing points by using the acoustic emission signals generated by damaging different shearing points is solved. If the elastic wave in the grouping sequence j arrives at the time trIf the number is less than 4, enough polynomial solutions cannot be formed to solve the coordinates of the shearing points by using the generated acoustic emission signals.
(5) Establishing an adaptive value function of the position of the acoustic emission signal, and setting the time of the k-th sensor to be
Figure BDA0002050954750000121
In the formula: t is the acoustic emission signal occurrence time, (x)k,yk,zk) (ii) is the kth sensor coordinate;
(x, y, z) is the location of the acoustic emission signal source; v is the equivalent velocity of the acoustic emission elastic wave propagating in the block on the structural plane. T received by the kth sensorkRepresenting the arrival time of the elastic wave;
the time difference between two adjacent sensors k +1 and k is
Figure BDA0002050954750000122
In the formula:
Figure BDA0002050954750000131
Figure BDA0002050954750000132
function for distinguishing position adaptive value of acoustic emission signal as
Figure BDA0002050954750000133
In the formula, △ WKThe number of the acoustic emission sensors is 6, which is the difference between the time when the k +1 th sensor and the time when the k sensors monitor;
(6) initializing the particle group to make the size of the group be N-80, and making the position X of every particle in the group in the flight spaceiX, y, z, V, i 1,2, … …, N, learning factor c1＝c22.05, the positioning accuracy requires epsilon0＝1.5×10-10Initializing the coordinates of an acoustic emission signal source in a space surrounded by an upper block and a lower block of a structural surface, wherein x belongs to (0, 150) mm, y belongs to (0, 120) mm, and z belongs to (0, 75) mm, initializing the equivalent speed range V of acoustic emission elastic waves belongs to (0, 7000) m/s, initializing the flight algebra n of a particle swarm to be 0, and randomly assigning the initial position of the particle swarm in the range;
(7) inputting arrival time of elastic waves monitored by all acoustic emission sensors in the jth group according to the group sequence j
Figure BDA0002050954750000134
Document calculating the arrival time differences Δ W between the k acoustic emission sensors within each group jk jThen, the arrival time difference Δ W is obtainedk jK acoustic emission sensor coordinates (x)k,yk,zk) Requirement epsilon for positioning precision of file and particle swarm0Substituting the initial positions of the particle groups in the step (6) into the step (5) to calculate the adaptive value of each particle i at the jth time
Figure BDA0002050954750000135
The group number j represents the shearing frequency, each group sequence is a primary acoustic emission signal generated after a shearing point is damaged, and the globally optimal acoustic emission source coordinate and the optimal acoustic emission source coordinate in the particle individual flight are determined according to the adaptive value Q;
(8) if it is
Figure BDA0002050954750000141
Then the acoustic source coordinates (x, y, z) are output, defining the historically optimal acoustic source coordinate P for the ith particlei＝(Pi1,Pi2,Pi3) (x, y, z) in
Figure BDA0002050954750000142
Minimum value of medium
Figure BDA0002050954750000143
Obtaining an optimal acoustic emission source position P for the entire population of particlesg＝(Pg1,Pg2,Pg3) And the calculation is finished at this time,
otherwise, updating the particle position by applying an acoustic emission source particle position updating formula, and then performing the steps (7) to (8) until the particle position is updated
Figure BDA0002050954750000144
Or the flight algebra n exceeds the limit, the calculation result is output.
Acoustic emission source, particle position update formula:
Figure BDA0002050954750000145
Figure BDA0002050954750000146
in the formula: c. C1＝c22.05 is a learning factor that is not negative constant; r is1And r2Is between [0,1]A random number in between; vector Pi＝(Pi1,Pi2,Pi3) And Pg＝(Pg1,Pg2,Pg3) The optimal acoustic emission source coordinates searched for the ith particle so far and the optimal acoustic emission source coordinates searched for the entire particle so far, respectively; phi is a compression factor, and the next particle search range is reduced by the compression factor during iteration, so that the particle search efficiency can be improved。
Coordinates of six sensors in the experiment are (15,0,18.75), (60,0,56.25), (135,0,18.75), (15,120,56.25), (90,120,18.75), (135,120,56.25), when 2624 arrival times are monitored by the acoustic emission system, the steps (7) to (8) are repeated to calculate the arrival time difference Δ W between each acoustic emission sensor in each grouping sequencek jThe 179 coordinates (x, y, z) obtained by the particle swarm algorithm constitute the acoustic source coordinate set, as shown in fig. 7.
If the locking value D is not adopted in the step (4)t＝S/VsFor the arrival time t of elastic waverGrouping is performed, and referring to fig. 4 and 5, the arrival time t of the elastic waves received by the 6 sensors is input according to the step (7)rCalculating the time-to-time difference Δ W between the 6 acoustic emission sensorsk jThen, the arrival time difference Δ W is obtainedk jK acoustic emission sensor coordinates (x)k,yk,zk) Requirement epsilon for positioning precision of file and particle swarm0Substituting the adaptive value of each particle i at the jth time in the step (6) into the step (5) to calculate
Figure BDA0002050954750000151
Then the arrival time t of the elastic wave received by the 6 sensors used in the second calculationrThe arrival times of the elastic waves with the sequence numbers 7, 8, 10, 12, 13 and 14 are respectively: 26.784894, 26.784909, 30.549251, 30.549266, 30.549272 and 30.549300, the position of the acoustic emission signal source calculated by using the data is obviously different from the position of the acoustic emission signal source calculated by using the data of the group 2 sequence in fig. 5, so the accuracy of judging the position of the acoustic emission signal source is obviously improved in the step (4). (9) Shearing damage coordinate processing, extracting the acoustic emission source coordinates obtained in the step (8), and selecting the acoustic emission source coordinates satisfying 0<x<150mm and 0<y<And (4) eliminating the acoustic emission coordinates which do not meet the requirements at the coordinates of 120 mm. And extracting the coordinate values screened in the previous step, projecting the coordinate values to a structural plane surface neutral plane to obtain a final coordinate set (x, y) of the acoustic emission source, and drawing a shear failure graph as shown in fig. 8 and 9.
Control group
When 6 acoustic emission sensors are arranged in the same plane and 6 sensors are symmetrically distributed, as shown in fig. 10-12, when an acoustic emission damage source is located on a symmetry axis AB line, the first acoustic emission sensor and the fourth acoustic emission sensor receive the same time, the second acoustic emission sensor and the fifth acoustic emission sensor receive the same time, the third acoustic emission sensor and the fifth acoustic emission sensor receive the same time, the 6 acoustic emission sensors have 1/2 sensors which are consistent time, the time difference between the acoustic emission sensors which are same time is close to zero, and when positioning calculation is carried out, pathological matrix calculation is easily caused, and the positioning result error is larger.

Claims (3)

1. A method for positioning a shearing failure position of a rock structural surface in a direct shear test is characterized by comprising the following steps:
s1, manufacturing a natural structural surface test block with mutually matched contact surfaces, dividing the structural surface test block into an upper structural surface block and a lower structural surface block which are equal in size, and arranging acoustic emission sensors according to an acoustic emission sensor monitoring arrangement scheme on the structural surface, wherein the acoustic emission sensor monitoring arrangement scheme on the structural surface is as follows:
(1) six acoustic emission sensors are arranged on a structural surface to be monitored in a direct shear test, the acoustic emission sensors are distributed on the left side surface and the right side surface of a block test block on the structural surface along the shearing direction, and three acoustic emission sensors on each side surface form a unit column; the length of the upper block of the structural surface along the shearing direction is L, and the height of the upper block of the structural surface is H;
(2) the distances between the acoustic emission sensors of the odd-numbered sequence and the even-numbered sequence in the two unit rows and the top surface of the block on the structural surface are respectively different;
(3) the distances between the acoustic emission sensors positioned in the middle sequence in each unit column and the end surface on one side of the structural surface upper block are unequal, and the distances between the acoustic emission sensors positioned in the two end sequences and the end surfaces on the two sides of the structural surface upper block are equal;
s2, establishing a coordinate system in the structural surface upper block, and establishing a txt format file according to the coordinates and the number k by the acoustic emission sensors arranged in the above way;
s3, calculating the acoustic emission sensor arranged in the modeMeasuring the space distance S between two sensors with the longest middle space distance by using a wave velocity detector to measure the wave velocity V of the elastic wave of the structural surfacesObtaining a lockout value Dt＝S/Vs；
S4, a structural surface test block shearing experiment and acoustic emission monitoring are synchronously carried out, an acoustic emission system monitors the whole shearing experiment until the experiment is finished, acoustic emission signals are recorded through the emission sensors, the arrival time of each elastic wave monitored by the six acoustic emission sensors is output, and a locking value D is usedtGrouping and sequencing the arrival time of the monitoring elastic wave:
(R1) setting the arrival time t of the R-th elastic waverThe arrival time of the first elastic wave is added with a locking value DtWhen the locking is obtained, selecting the arrival time t of the r-th elastic waverArrival time t of all elastic waves in the period of time of arrival of the lockrForming a grouping sequence j;
(R2) arrival time t of elastic wave in packet sequencerIf the number is less than 4, the elastic waves are not subjected to packet sequencing, and the arrival time t of the elastic waves later than the last bit in the packet sequence isrSetting the arrival time of the first elastic wave, and repeating the previous step R1 to form a new grouping sequence j;
(R3) arrival time t of elastic wave in packet sequence jrIf the number is not less than 4, the arrival time t of the elastic waves in the packet sequence is determinedrAssigning a grouping number j;
(R4) setting the arrival time tr of the elastic wave later than the last bit in the grouping sequence of step R3 as the arrival time of the first elastic wave, repeating steps R1 to R3, and forming a new grouping sequence;
grouping all the elastic wave arrival times, inputting the serial number k of each acoustic emission sensor, the elastic wave arrival times acquired by each acoustic emission sensor and the group number sequence r into a txt text for storage;
s5, according to the arrival time difference positioning principle, establishing an acoustic emission position adaptive value function, and setting a kth sensor to calculate the arrival time as follows:
Figure FDA0002324183260000021
in the formula: t is the time of occurrence of the acoustic emission event, (x)k,yk,zk) (ii) is the kth sensor coordinate; (x, y, z) is the location of the source of the acoustic emission event during the shearing of the structural plane; v is the equivalent speed of acoustic emission elastic wave propagating in the block on the structural surface; t received by the kth acoustic emission sensorkRepresenting the arrival time of the elastic wave;
the time difference between the two adjacent acoustic emission sensors k +1 and k is
Figure FDA0002324183260000031
In the formula:
Figure FDA0002324183260000032
Figure FDA0002324183260000033
function of adaptive value for distinguishing acoustic emission event position as
Figure FDA0002324183260000034
In the formula, △ WKThe difference between the times when the k +1 th acoustic emission sensor and the k-th acoustic emission sensor are monitored;
s6, initializing learning factor c of particle swarm positioning algorithm1、c2Group size N, positioning accuracy requirement ε0The parameters are that the acoustic emission event source coordinates, the initial elastic wave speed range and the flight algebra n are initially assigned in the block space range on the structural surface;
s7, inputting the coordinates txt file of the six acoustic emission sensors and all the elastic wave arrival time files in the jth grouping sequence into the adaptive value function of the step S5 according to the grouping sequence j, and calculating the adaptive value of each particle i in the jth grouping sequence in the step S5
Figure FDA0002324183260000035
S8, if
Figure FDA0002324183260000036
Then the output acoustic source coordinate X ═ X, y, z, defines the historically best acoustic source coordinate P for the ith particlei＝(Pi1,Pi2,Pi3) (x, y, z) in
Figure FDA0002324183260000037
Minimum value of medium
Figure FDA0002324183260000038
Obtaining an optimal acoustic emission source position P for the entire population of particlesg＝(Pg1,Pg2,Pg3) The calculation is finished;
otherwise, the particle position is updated by applying the particle position updating formula of the acoustic emission source, and the steps S7-S8 are repeated until the particle position is updated
Figure FDA0002324183260000039
Or the flight algebra n exceeds the limit, the calculation result P is outputg＝(Pg1,Pg2,Pg3) I.e., the coordinates of the shear failure;
s9, repeating the steps S7-S8 according to the arrival time t of the elastic wave in each grouping sequencerCalculating the coordinate of the shearing damage;
s10, screening out coordinates of shear failure in the space range of the upper block of the structural surface by combining the shear surface shear characteristics, projecting the coordinates of shear failure to the contact surface of the upper block of the structural surface and the lower block of the structural surface to obtain the coordinates of shear failure occurring on the structural surface, and drawing a structural surface shear failure graph.
2. The method of claim 1, wherein the acoustic emission source (particle location update formula):
Figure FDA0002324183260000041
Figure FDA0002324183260000042
in the formula: c. C1＝c2A learning factor greater than 2; r is1And r2Is between [0,1]A random number in between; vector Pi＝(Pi1,Pi2,Pi3) And Pg＝(Pg1,Pg2,Pg3) The optimal acoustic emission source coordinates searched for the ith particle so far and the optimal acoustic emission source coordinates searched for the entire particle so far, respectively;
Figure FDA0002324183260000043
is the compression factor.
3. The method according to claim 1, wherein the fitness value of each particle i in the j-th subgroup sequence in step S5 is calculated
Figure FDA0002324183260000045
Comprises the following steps: inputting arrival time of elastic waves monitored by all acoustic emission sensors in the jth group according to the group sequence j
Figure FDA0002324183260000044
Document calculating the arrival time differences Δ W between k acoustic emission sensors within each group jk jThen, the arrival time difference Δ W is obtainedk iK acoustic emission sensor coordinates (x)k,yk,zk) Requirement epsilon for positioning precision of file and particle swarm0Substituting into step S5, calculating the adaptive value of each particle i in the jth group according to the initial position of the particle group in step S6.
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