CN114002326B - Detection method for loaded rock damage - Google Patents

Detection method for loaded rock damage Download PDF

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CN114002326B
CN114002326B CN202111304758.0A CN202111304758A CN114002326B CN 114002326 B CN114002326 B CN 114002326B CN 202111304758 A CN202111304758 A CN 202111304758A CN 114002326 B CN114002326 B CN 114002326B
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rock sample
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CN114002326A (en
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龙士国
何炼
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Xiangtan University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/28—Details, e.g. general constructional or apparatus details providing acoustic coupling, e.g. water
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0019—Compressive
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075—Strain-stress relations or elastic constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/0289—Internal structure, e.g. defects, grain size, texture
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/30—Assessment of water resources

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  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The invention discloses a method for detecting loaded rock damage, which comprises the steps of simultaneously carrying out acoustic wave test and uniaxial compression test on rock materials to be detected, carrying out data processing on obtained acoustic wave signals to obtain acoustic wave signal frequency domain diagrams of rock samples under different loads, dividing frequency intervals in the acoustic wave signal frequency domain diagrams into a plurality of equal-width frequency bands, selecting frequency bands with concentrated acoustic wave signals and obvious peaks in all the divided equal-width frequency band intervals, and calculating frequency domain energy E of the acoustic wave signals of the rock samples in the selected intervals f Energy E in the frequency domain f And substituting the energy ratio delta of the frequency domain of the rock sample acoustic wave signal into the formula (2), wherein the larger the delta value is, the more cracks are, and the larger the damage is. Compared with the prior art, the method for detecting the loaded rock damage provided by the invention processes the received sound wave signals, and judges the detected rock sample damage through the defined dimensionless parameter frequency domain energy ratio delta.

Description

Detection method for loaded rock damage
Technical Field
The invention relates to a detection method, belongs to the technical field of sound wave detection, and particularly relates to a detection method for damage and destruction of rock materials in a loading process.
Background
Rock is used as a brittle composite material, and when external force acts, the rock is damaged, so that the rock is unstable and damaged, the bearing capacity of the structure is reduced, and huge engineering problems are possibly caused, so that the detection of the damage mechanism of loaded rock is particularly important.
The acoustic wave detection is used as a portable, effective and convenient-to-operate nondestructive measurement mode, is widely applied to detecting the damage rule of the internal structure of the rock, and is widely used for carrying out a great deal of indoor experimental study on the acoustic characteristic research in the compressed rock damage process at present by domestic researchers, yang Shuang and the like to carry out wave velocity change characteristic and spectrum analysis on marble in the uniaxial compression process, so that the damage rule of the rock can be judged by the high-frequency signal energy when the pores and cracks in the rock are compacted, the longitudinal wave velocity is increased and the low-frequency energy of a frequency domain signal is gradually transferred to the high-frequency energy. Ji Hongan et al have found that the sudden increase in the high frequency and high amplitude frequency signal indicates a risk of damaging the granite by experimental studies of the frequency characteristics of the acoustic signal under uniaxial stress of the granite. For the quantitative relation between the frequency domain signal characteristic parameters and the rock material mechanical parameters, the rapid and effective identification of rock critical damage precursor information is difficult to realize.
Disclosure of Invention
The invention aims at overcoming the defects of the prior art and provides a detection method for loaded rock damage, which is to acquire sound wave signals by detecting the sound waves of the rock in the uniaxial compression process and then process the data of the extracted signals, thereby achieving the purpose of rapid and accurate detection.
The invention provides a method for detecting loaded rock damage, which is to detect rock sample sound wave under different load actions of rock material to be detected, divide the frequency interval in the sound wave signal frequency domain diagram obtained by sound wave detection into a plurality of equal-width frequency bands, select the frequency band with concentrated sound wave signals and obvious peak value in all the divided equal-width frequency band intervals, calculate the frequency domain energy E of the rock sample sound wave signals in the selected interval f By the obtained frequency domain energy E f And calculating the frequency domain energy ratio delta of the rock sample acoustic wave signals under different loads, wherein the larger the delta value is, the more cracks are, and the larger the damage is.
The technical scheme is as follows: the method for detecting the loaded rock damage comprises the steps of simultaneously carrying out sonic testing and uniaxial compression testing on a rock material to be detected, carrying out data processing on sonic signals of all loaded rock samples to obtain sonic signal frequency domain diagrams of the rock samples under different loads, dividing frequency intervals in the sonic signal frequency domain diagrams of the rock samples under different loads into a plurality of equal-width frequency bands, selecting frequency bands with concentrated sonic signals and obvious peaks in all the divided equal-width frequency band intervals, and calculating the frequency domain energy E of the sonic signals of the rock samples in the selected intervals according to a formula (1) f The stress strain data obtained in the uniaxial compression test process and the frequency domain energy E calculated by the formula (1) are compared f Substituting formula (2) to calculate the frequency domain energy ratio delta of the rock sample acoustic wave signals under different loads, thereby obtaining the rock breaking moment (the larger the force acting on the rock sample is, the more rock cracks will increase, namely the rock sampleThe damage increases, and thus the larger the delta value, the more cracks and damage) the larger the corresponding delta value:
wherein the frequency domain energy E f For acoustic signals in the interval (f 1 ，f 2 ) The energy of the above, A (f), is the change curve of the acoustic wave frequency domain signal diagram obtained by fast Fourier change, f 1 The initial frequency f of the frequency band with concentrated and obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram 2 Cut-off frequency of a frequency band which is concentrated and has obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram;
wherein the frequency domain energy ratio delta is the ratio of the frequency domain energy of the sound wave signal of the rock sample in the stress state to the frequency domain energy of the sound wave signal of the rock sample in the complete state in the same frequency band, A i (f) A is the change curve of the frequency domain diagram of the acoustic signal of the rock sample in the stress state 0 (f) Is the change curve of the acoustic wave signal frequency domain diagram of the rock sample in the complete state, f 1 The initial frequency f of the frequency band with concentrated and obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram 2 Is the cut-off frequency of the frequency band with concentrated and obvious peak value of the selected sound wave signal in the sound wave signal frequency domain diagram.
Preferably, the method may comprise the steps of:
step 1), carrying out acoustic wave detection on a rock sample to be detected under different loads, and carrying out data processing on the obtained acoustic wave signals to obtain an acoustic wave signal frequency domain diagram of the rock sample to be detected under different loads;
step 2) dividing the whole frequency interval of the acoustic wave signals into a plurality of equal-frequency bands according to the acoustic wave signal frequency domain diagram obtained in the step 1, selecting the frequency bands with concentrated acoustic wave signals and obvious peaks, and calculating by using a formula (1) to obtain the acoustic wave signals of the rock sample in the selected intervalFrequency domain energy E of (2) f ；
Step 3) the frequency domain energy E obtained in the step 2 f Substituting the value into the formula (2) to calculate the frequency domain energy ratio delta, and judging the damage size of the rock sample according to the value of the frequency domain energy ratio delta.
Preferably, the method may comprise the steps of:
step S1: according to the stress value and the strain value in the uniaxial compression process of the rock sample to be measured, calculating the uniaxial compressive strength sigma of the rock sample to be measured c ；
Step S2: in the uniaxial compression process of the rock sample to be detected, carrying out acoustic wave detection on the rock sample to be detected to obtain an acoustic wave signal time domain diagram of the rock sample to be detected;
step S3: dividing the whole frequency interval of the acoustic wave signal into a plurality of equal-frequency bands according to the acoustic wave signal time domain diagram obtained in the step S2, selecting a frequency band with concentrated acoustic wave signals and obvious peaks, (researches show that sudden increase of high-frequency and high-amplitude frequency signals can indicate damage danger of rock, so that the frequency is selected to be higher and the peak amplitude is obvious to be researched and analyzed), and calculating the acoustic wave signal frequency domain energy E of the rock sample to be tested in the selected frequency interval by utilizing the formula (1) f ；
Step S4: the frequency domain energy E obtained in the step S3 f Substituting the energy ratio delta into the formula (2) to calculate the frequency domain energy ratio delta.
Preferably, a uniaxial compression test is carried out on the rock test piece, displacement control is adopted for load application, and axial load is 0.2mm/min (the test effect is best) until the rock test piece is damaged, so that a stress strain curve of the rock sample to be tested is obtained.
It should be noted that, when the inventors studied the acoustic characteristics of the rock sample, they found that the acoustic frequency domain signal of the rock sample was mainly concentrated at 20-140kHz, and when the load exceeded 40kN, the peak point of amplitude was more in the region of lower frequency, but the peak point of amplitude was significantly increased and the signal was concentrated in the region of higher frequency, therefore, the inventors selected the region of higher frequency for specific analysis and found the acoustic signal frequency domain energy formula (1) of the frequency bandAnd the frequency domain energy is gradually increased along with the increase of the load by combining the test piece stress stage analysis. In order to compare the frequency domain energy of the acoustic wave signals of the rock sample under different stress levels and eliminate the influence of test measurement errors, the frequency domain energy of the acoustic wave signals of the rock sample under different stress levels in the same frequency band is subjected to ratio to obtain a frequency domain energy ratio formula (2)>As a result, the frequency domain energy ratio is found to increase with the increase of stress, and the test result is more accurate by defining the dimensionless parameter frequency domain energy ratio delta.
Compared with the prior art, the method for detecting the loaded rock damage provided by the invention carries out data processing on the received sound wave signals, and then defines a dimensionless parameter frequency domain energy ratio delta, so that the damage state of the detected rock sample is judged. The method has the advantages of simple and convenient flow and obvious advantages:
(1) According to the invention, whether rock damage occurs can be predicted by measuring the frequency domain energy of the rock acoustic wave signal;
(2) According to the invention, the ratio of the frequency domain energy of the rock sample acoustic wave signal in the higher frequency section is defined as the frequency domain energy ratio delta, so that the influence caused by experimental errors is reduced, and the result is more accurate.
Description of the drawings:
FIG. 1 is a schematic view of the connection between a rock sample and equipment according to example 1 of the present invention;
FIG. 2 is a stress-strain curve of a rock sample provided in example 1 of the present invention;
FIG. 3 is a frequency domain diagram of acoustic signals of the rock sample provided in example 1 of the present invention under the load of 0-35 kN;
FIG. 4 is a frequency domain diagram of acoustic signals of the rock sample provided in example 1 of the present invention under the action of a load of 40-68 kN;
FIG. 5 is a graph of energy versus stress in the frequency domain for a rock sample provided in example 1 of the present invention;
FIG. 6 is a graph of the energy ratio in the frequency domain versus stress for a rock sample according to example 1 of the present invention;
1, a rock sample; 2. a pressure-bearing transducer; 3. an acoustic wave detector; 4. microcomputer controlled electronic universal tester.
The specific embodiment is as follows:
the invention is further described in detail below with reference to the drawings and detailed description.
Example 1
(1) Manufacturing a rock test piece: and selecting the rock sample 1 to be measured, and processing to obtain a standard cylindrical rock test piece A, a test piece B and a test piece C, wherein the radius R=25 mm of the size of all the test pieces and the length l=100 mm.
(2) And vaseline is uniformly smeared on the upper surface and the lower surface of the rock test piece, the upper surface and the lower surface are respectively contacted with the pressure-bearing energy converter 2, a microcomputer control electronic universal tester 4 is fixed on the other side of each pressure-bearing energy converter 2, and the acoustic wave detector 3 is connected with the pressure-bearing energy converter 2, as shown in figure 1. The Vaseline is used as a coupling agent, so that the pressure-bearing transducer 2 is better contacted with the rock sample 1, measurement data is accurate, and errors are reduced.
(3) And starting the microcomputer-controlled electronic universal tester to perform a uniaxial compression test on the rock test piece, automatically acquiring and recording stress, strain and other data by a system in the experimental process, and drawing a stress-strain curve as shown in figure 2.
(4) And (3) in the uniaxial compression test process of the step (3), respectively transmitting and receiving sound waves to the upper and lower surfaces of the rock test piece through the instrument of the step (2) when the stress load of the rock test piece is 0kN, 1kN, 2kN, 3kN, 4kN and 4kN, and storing the obtained sound wave signals until the rock test piece is damaged or the sound waves cannot be identified.
(5) The data processing is performed on the acoustic wave signals under different loads obtained in the step (4) to obtain a frequency domain diagram (see fig. 3 and 4) of the rock test piece under different loads, and as can be seen from the above frequency domain diagram, the acoustic wave frequency domain signals of the rock test piece to be tested in the embodiment are mainly concentrated at 20-140kHz, the frequency signal interval can be equally divided into 20-60kHz, 60-100kHz and 100-140kHz intervals, the peak point of the amplitude in the higher frequency interval (100-140 kHz) can be seen to be obviously increased, and the signal is concentrated, therefore, the inventor chooses to utilize the formula (1) (f) in the frequency interval of 100-140kHz 1 Set to 100kHz, f 2 Set to 140kHz) to calculate the frequency domain energy E of the rock-like acoustic wave signal in the frequency band (the interval of 100-140kHz in the embodiment) with concentrated and obvious peak value of the selected acoustic wave signal f 。
In order to obtain the relation between the stress of the rock test piece and the frequency domain energy of the rock test piece, substituting the force acting on the rock test piece into the stress of the rock test piece according to the formula (3) to obtain the frequency domain energy of the sound wave signal of the rock test piece under different stress states, wherein the obtained result is shown in the table 2, and the relation between the frequency domain energy of the sound wave signal of the rock test piece and the stressed stress is drawn according to the data of the table 2 as shown in the figure 5.
Where σ is the stress acting on the rock specimen, F is the force acting on the rock specimen, S is the area of the stressed cross-section of the rock specimen (s=pi R 2 R=25 mm in this example).
TABLE 2 frequency domain energy of rock sample sonic signals at different stress states
From Table 2 and FIG. 5, it can be seen that the frequency domain energy E of the acoustic wave signal of the rock sample f And shows an increasing trend with increasing load.
(6) In order to compare the energy of the frequency spectrum signal of the rock sample 1 under different stress levels and exclude the influence of experimental measurement errors, the frequency domain energy E of the acoustic wave signal of the rock sample obtained in the step (4) is calculated f Substituting formula (2) to obtain frequency domain energy ratio delta, calculating the result as shown in table 3 (the measured waveform will be different due to different applied forces, the calculated delta value will be different, the delta value will be a corresponding delta value with the change of stress, and each stress value will be a corresponding delta value), and plotting the acoustic wave signal of the rock test pieceGraph of number-domain energy ratio δ versus stress σ (as shown in fig. 6):
wherein the frequency domain energy ratio delta is the ratio of the frequency domain energy of the rock sample 1 in the stress state to the frequency domain energy of the rock sample in the complete state in the same frequency band, A i (f) A is a change curve of a sound wave signal frequency domain diagram obtained by fast Fourier change of a rock sample in a stress state 0 (f) A change curve f of a sound wave signal frequency domain diagram obtained by fast Fourier change of the rock sample in an intact state 1 The initial frequency f of the frequency band with concentrated and obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram 2 Cut-off frequency of frequency band with concentrated and obvious peak value of selected sound wave signal in sound wave signal frequency domain diagram, f in the embodiment 1 ＝100kHz，f 2 ＝140kHz。
TABLE 3 frequency domain energy ratio delta of acoustic signals of rock samples under different stress states
(7) By observing fig. 2 and 6, the change of the stress process of the rock sample can be divided into the following stages:
in fig. 2, when the rock is in the pore compaction to elastoplastic stage, the variation range of the stress sigma value is between 0MPa and 10.19MPa, and the corresponding variation range of the delta value is between 1 and 1.80 as can be seen from table 3, as can be seen from fig. 6, the frequency domain energy ratio delta is in a linear increasing trend along with the increase of the stress sigma, the rock is closed due to stress so as to generate energy propagation, and finally smaller sonic frequency signals are generated, namely the stress sigma value is smaller, the corresponding delta value variation is smaller, the microcracks in the rock are compacted, and the sample damage is smaller;
when the load is gradually increased, namely the stress sigma is increased, the stress and the strain are continuously increased, the rock is in a plastic stage, the change range of the stress sigma value is between 12.22MPa and 25.98MPa, the corresponding change range of the delta value is between 3.02 and 5.26, and the frequency domain energy ratio delta shows a nonlinear rapid increase trend along with the stress sigma in the stage, as shown in fig. 6, in addition, the delta value is suddenly and remarkably increased, namely the delta value is found in fig. 6 a Corresponding point when=3.02, corresponding stress is σ a ＝12.22MPa，σ a ＝0.3σ c (σ c Limit stress, a value of 36.12 MPa), this point can be considered as the point at which the elastic phase is transformed into the microcrack development phase; the stress sigma is gradually increased, the corresponding delta value is increased, the fact that microcracks in the rock test piece start to expand and new cracks appear along with the microcracks is shown, the volume of the test piece starts to expand, the damage of the test piece is increased, and the test piece reaches the early stage of damage;
as the load increases further, FIG. 2 shows that the strain increases continuously until the rock breaks, the rock is in the main breaking stage, the variation range of the stress sigma value is 25.98 MPa-36.12 MPa, and the corresponding variation range of the delta value is 5.26-5.63 as shown in Table 3, and as shown in FIG. 6, the frequency domain energy ratio delta shows a linear and slow increasing trend along with the stress sigma, in addition, when the rock frequency domain energy ratio delta increases continuously and reaches the maximum value, the corresponding stress is the peak stress sigma c The test piece of rock has a fracture penetrating the whole test piece, the main fracture surface of the rock is marked, the rock is broken, the damage reaches the maximum at the moment, the test piece gradually loses the bearing capacity until the test piece is completely broken, and therefore, the test piece is in a broken state when the frequency domain energy ratio of the test piece reaches the maximum.
According to the analysis, in the loading process of the rock, the energy of the frequency domain is linearly and slowly increased compared with that of the rock in the elastic stage along with the increase of stress, so that the damage is small; then in the plastic phase, the frequency domain energy ratio delta suddenly increases and presents a nonlinear increase, i.e. the sudden increase of the frequency domain energy ratio predicts the risk of rock destruction; finally, slowly and linearly increasing the delta until the main breaking stage, and gradually increasing the number of cracks of the rock when the frequency domain energy ratio delta is increased, namely gradually increasing the breaking surface of the rock, gradually increasing the damage, and gradually losing the bearing capacity of the test piece; therefore, the damage and destruction process of the loaded rock can be rapidly judged by utilizing the frequency domain energy ratio delta, and the measurement result is rapid and accurate.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the invention is described in terms of the preferred embodiments, it is not intended to be limiting. Therefore, the simple modification or variation of the above embodiments according to the technical substance of the present invention shall fall within the scope of the protection of the technical solution of the present invention.

Claims (4)

1. The method for detecting the loaded rock damage is characterized by comprising the steps of carrying out acoustic wave detection on a rock sample under different loads on a rock material to be detected, dividing a frequency interval in a sound wave signal frequency domain diagram obtained by the acoustic wave detection into a plurality of equal-width frequency bands, selecting a frequency band with concentrated sound wave signals and obvious peaks in all the divided equal-width frequency band intervals, and calculating frequency domain energy E of the sound wave signals of the rock sample in the selected interval by using a formula (1) f The obtained frequency domain energy E f Substituting the formula (2) to calculate the frequency domain energy ratio delta of the rock sample acoustic wave signals under different load actions, wherein the larger the delta value is, the more cracks are, and the larger the damage is:
wherein the frequency domain energy E f For acoustic signals in the interval (f 1 ，f 2 ) The energy of the ultrasonic wave is A (f) is the change curve of the sound wave frequency domain signal diagram, f 1 The initial frequency f of the frequency band with concentrated and obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram 2 Cut-off frequency of a frequency band which is concentrated and has obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram;
wherein the frequency domain energy ratio delta is the ratio of the frequency domain energy of the sound wave signal under the stress state of the rock sample in the same frequency band to the frequency domain energy of the sound wave signal under the complete state of the rock sample, A i (f) A is the change curve of the frequency domain diagram of the acoustic wave signal of the rock sample in the loaded state 0 (f) Is the change curve of the acoustic wave signal frequency domain diagram of the rock sample in the complete state, f 1 The initial frequency f of the frequency band with concentrated and obvious peak value of the selected sound wave signals in the sound wave signal frequency domain diagram 2 Is the cut-off frequency of the frequency band with concentrated and obvious peak value of the selected sound wave signal in the sound wave signal frequency domain diagram.
2. The method for detecting damage to a loaded rock of claim 1, comprising the steps of:
step 1), carrying out acoustic wave detection on a rock sample to be detected under different loads, and carrying out data processing on the obtained acoustic wave signals to obtain an acoustic wave signal frequency domain diagram of the rock sample to be detected under different loads;
step 2) dividing the whole frequency interval of the acoustic wave signal into a plurality of equal-frequency bands according to the acoustic wave signal frequency domain diagram obtained in the step 1, selecting the frequency band with concentrated acoustic wave signals and obvious peak values, and calculating by using the formula (1) to obtain the frequency domain energy E of the rock sample acoustic wave signal in the selected interval f ；
Step 3) the frequency domain energy E obtained in the step 2 f Substituting the value into the formula (2) to calculate the frequency domain energy ratio delta, and judging the damage size of the rock sample according to the value of the frequency domain energy ratio delta.
3. The method for detecting damage to a loaded rock of claim 1, comprising the steps of:
step S1: carrying out uniaxial compression on the rock sample to be tested, and measuring the stress and strain of the rock sample to obtain a stress-strain curve of the rock sample to be tested;
step S2: in the process of uniaxial compression of the rock sample to be detected, simultaneously carrying out acoustic wave detection on the rock sample to be detected, and carrying out data processing on the obtained acoustic wave signals to obtain acoustic wave signal frequency domain diagrams of the rock sample to be detected under different loads;
step S3: dividing the whole frequency interval of the acoustic wave signal into a plurality of equal-frequency bands according to the acoustic wave signal frequency domain diagram obtained in the step S2, selecting the frequency band with concentrated acoustic wave signals and obvious peak values, and calculating by using the formula (1) to obtain the frequency domain energy E of the rock sample acoustic wave signal in the selected interval f ；
Step S4: the frequency domain energy E obtained in the step S3 f Substituting the energy ratio delta into the formula (2) to calculate the frequency domain energy ratio delta.
4. A method for detecting loaded rock damage according to claim 3, wherein the rock specimen is subjected to uniaxial compression test, the load is applied by displacement control, and the axial load is applied by 0.2mm/min until the rock specimen is broken, so as to obtain a stress strain curve of the rock sample to be detected.
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KR20130133385A (en) * 2012-05-29 2013-12-09 대한민국 (관리부서:국립문화재연구소) Calculating method for weathering degree of rock using rebound hardness teste
CN104865124A (en) * 2015-05-30 2015-08-26 重庆地质矿产研究院 Shale brittleness index determination method based on rock stress-strain curve and ultrasonic longitudinal wave velocity

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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