Method for preparing rock samples with different crushing degrees through cooperation of quantitative dynamic load and three-dimensional scanning

Abstract

The invention discloses a method for preparing rock samples with different crushing degrees through cooperation of quantitative dynamic load and three-dimensional scanning, and the method comprises the following steps: screening to-be-prepared rock samples according to pore fractures of the rock samples, the density of the rock samples and the ultrasonic longitudinal wave velocity of the rock samples to obtain to-be-prepared samples; carrying out dynamic load impact on the to-be-prepared sample, and monitoring the generation condition of internal cracks of the to-be-prepared sample by adopting acoustic emission to obtain an acoustic emission monitoring result; carrying out dynamic load impact and classification on a to-be-crushed rock sample based on the acoustic emission monitoring result to obtain a to-be-screened rock sample; and carrying out porosity screening on the rock samples to be screened by adopting three-dimensional fracture scanning to obtain rock samples with different crushing degrees. According to the method, the rock samples with different crushing degrees can be prepared through the methods of three-dimensional pore crack scanning, rock ultrasonic testing, laboratory testing, qualitative and quantitative analysis and the like, and a premise is provided for research on analyzing the re-bearing mechanical characteristics of rock masses with different crushing degrees or stress paths.

Description

Technical Field

[0001] The invention belongs to the field of rock mechanics property research, and in particular relates to a method for preparing rock samples with different crushing degrees by using quantitative dynamic load and coordinated three-dimensional scanning. Background Art

[0002] Blasting excavation has always been the main construction method for rock excavation in underground engineering in civil engineering and mining engineering. It has the advantages of strong adaptability to rock geological conditions and low excavation cost. However, blasting excavation is easy to disturb the surrounding rock of the underground excavation space and affect the support quality of the support structure. Therefore, it is of great significance to study the stability and support design of the surrounding rock of the excavation space under different degrees of damage caused by dynamic load impact. Therefore, it is particularly necessary to study the mechanical properties and bearing capacity of rock masses with different degrees of damage. The premise of the research is to artificially pre-destroy the rock samples. The existing artificial pre-destruction methods cannot accurately and simply characterize the pore and fracture state of rock samples with different damage. Therefore, this technology provides a method for preparing rock samples with different degrees of damage by quantitative dynamic load and coordinated three-dimensional scanning, which provides a research premise for studying the re-bearing mechanical properties of rock masses with different degrees of crushing. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning, so as to solve the problems existing in the above prior art.

[0004] To achieve the above object, the present invention provides a method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning, comprising the following steps:

[0005] The rock samples to be prepared are screened according to the pores and cracks of the rock samples, the density of the rock samples and the ultrasonic longitudinal wave velocity of the rock samples to obtain the samples to be prepared;

[0006] The sample to be prepared is subjected to dynamic load impact, and acoustic emission is used to monitor the generation of cracks inside the sample to be prepared to obtain an acoustic emission monitoring result;

[0007] Based on the acoustic emission monitoring results, dynamic load impact and classification are performed on the rock samples to be crushed to obtain rock samples to be screened;

[0008] The porosity of the rock samples to be screened is screened by three-dimensional fracture scanning to obtain rock samples with different degrees of crushing.

[0009] Preferably, the selection conditions for the rock sample to be prepared include but are not limited to uniform texture and no obvious joints or cracks.

[0010] Preferably, the method for screening the rock sample to be prepared comprises:

[0011] The original pores and fractures of the rock samples were characterized by three-dimensional scanning, and the rock samples with undeveloped original pores and fractures and similar original porosity were selected as preliminary screening rock samples;

[0012] The natural density and ultrasonic longitudinal wave velocity of the preliminary screened rock samples are measured respectively, and rock samples with similar natural density and ultrasonic longitudinal wave velocity are selected as samples to be prepared.

[0013] Preferably, the three-dimensional scanning method includes but is not limited to CT scanning.

[0014] Preferably, the method of subjecting the sample to be prepared to dynamic load impact includes but is not limited to using a Hopkinson pressure bar with different impact air pressures to perform dynamic load impact.

[0015] Preferably, when the rock sample to be crushed is subjected to dynamic load impact, the impact gas pressure is determined according to the crushing degree rock sample requirement and the acoustic emission fracture feedback.

[0016] Preferably, the method for classifying the rock samples to be crushed after dynamic load impact comprises:

[0017] The internal cracks of the sample to be prepared are used as a criterion for judging the degree of crushing, and the degree of crushing is divided into slight crushing, moderate crushing and severe crushing according to the criterion.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention aims at studying the practical problem of the mechanical properties and stability evolution law of the surrounding rock of underground engineering under the influence of dynamic load and different geological conditions. Through three-dimensional pore and fracture scanning, acoustic emission test, laboratory test, qualitative and quantitative analysis and other methods, rock samples with different degrees of crushing are prepared, providing a research basis for subsequent research on the evolution law of mechanical properties of rock masses with different degrees of crushing under the influence of different influencing factors. This design method is simple and easy to implement, with strong technical innovation, high practicality and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 The figure is a schematic diagram of a method flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0024] Embodiment 1

[0025] like Figure 1 As shown, this embodiment provides a method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning, including the following steps:

[0026] The rock samples to be prepared are screened according to the pores and cracks of the rock samples, the density of the rock samples and the ultrasonic longitudinal wave velocity of the rock samples to obtain the samples to be prepared;

[0027] Dynamic load impact is applied to the sample to be prepared, and acoustic emission is used to monitor the generation of cracks inside the sample to be prepared, and the acoustic emission monitoring results are obtained;

[0028] Based on the acoustic emission monitoring results, the rock samples to be broken are subjected to dynamic load impact and classification to obtain the rock samples to be screened;

[0029] Three-dimensional fracture scanning is used to screen the porosity of the rock samples to be screened, and rock samples with different degrees of crushing are obtained.

[0030] Furthermore, the selection conditions for the rock sample to be prepared include but are not limited to uniform texture and no obvious joints or cracks.

[0031] Furthermore, the method for screening the rock sample to be prepared includes:

[0032] The original pores and fractures of the rock samples were characterized by three-dimensional scanning, and the rock samples with undeveloped original pores and fractures and similar original porosity were selected as preliminary screening rock samples;

[0033] The natural density and ultrasonic longitudinal wave velocity of the preliminarily screened rock samples were measured respectively, and rock samples with similar natural density and ultrasonic longitudinal wave velocity were selected as the samples to be prepared.

[0034] Furthermore, three-dimensional scanning methods include but are not limited to CT scanning.

[0035] Furthermore, the method of subjecting the sample to be prepared to dynamic load impact includes but is not limited to using a Hopkinson pressure bar with different impact air pressures to perform dynamic load impact.

[0036] Furthermore, when the rock sample to be crushed is subjected to dynamic load impact, the impact gas pressure is determined according to the crushing degree rock sample requirements and the acoustic emission crack feedback.

[0037] Furthermore, the method for classifying the rock samples to be crushed after dynamic load impact includes:

[0038] The internal cracks of the sample to be prepared are used as the criterion for judging the degree of crushing, and the degree of crushing is divided into slight crushing, moderate crushing and severe crushing according to the judgment criterion.

[0039] The specific implementation is as follows:

[0040] Taking a mine as an example, the specific implementation steps are:

[0041] In a calcite mine, the mining area is mainly marble engineering geological rock group, with medium rock integrity, medium hard rock and good rock quality grade. The mining tunnels are excavated by blasting, and the tunnels are greatly affected by blasting. It is urgent to study the mechanical properties of roof sandstone with different crushing degrees. Now marble with different crushing degrees is prepared.

[0042] (1) 18 marble 50mm×100mm standard uniaxial compression specimens with uniform texture and no obvious joints and fissures were subjected to three-dimensional pore and fissure scanning. The porosity of the three-dimensional scanned rock samples is shown in Table 1. Based on the scanning results, one specimen with a porosity of more than 5% and developed primary pores and fissures was eliminated. The remaining 17 specimens had similar porosities and undeveloped primary pores and fissures, with an average porosity of 2.94%. That is, 17 specimens with undeveloped primary pores and fissures and similar primary porosities were selected for the next step of preparation;

[0043] Table 1

[0044]

[0045] (2) The natural density and ultrasonic wave velocity of the above samples were measured respectively, and the strength of the rock samples was preliminarily predicted. Rock samples with similar natural density and ultrasonic longitudinal wave velocity were selected as the samples to be prepared. The test results of the natural density and ultrasonic wave velocity of the rock samples are shown in Table 2. Two samples with natural density and ultrasonic wave velocity that were significantly different from others were eliminated based on the test results.

[0046] Table 2

[0047]

[0048]

[0049] (3) Six specimens, DLY-1, DLY-3, DLY-7, DLY-9, DLY-13 and DLY-17, were randomly selected and subjected to dynamic impact using a Hopkinson pressure bar with six different impact air pressures of 1.00 MPa, 1.25 MPa, 1.35 MPa, 1.45 MPa, 1.50 MPa and 1.75 MPa. During the impact process, acoustic emission was used to monitor the generation of internal cracks in the specimens.

[0050] (4) After the dynamic load impact, the internal cracks generated by the acoustic emission monitoring feedback were used to set the damage degree of the specimens at three different air pressures of 1.25MPa, 1.45MPa, and 1.50MPa as the boundaries of slight crushing, moderate crushing, and severe crushing;

[0051] (5) According to the set impact air pressure values ​​of different degrees of rock sample damage, the remaining samples to be prepared are prepared into rock samples with different degrees of crushing by using the dynamic load quantitative impact air pressure method;

[0052] (6) Finally, the prepared rock samples with different degrees of crushing were subjected to CT three-dimensional pore and fracture scanning, and the porosity of the rock samples was used to characterize the different degrees of crushing. The pore and fracture ratio of the rock samples was analyzed. After three-dimensional fracture scanning characterization, the prepared rock samples met the requirements.

[0053] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning, characterized in that: The following steps are involved: The rock samples to be prepared are screened according to the pores and cracks of the rock samples, the density of the rock samples and the ultrasonic longitudinal wave velocity of the rock samples to obtain the samples to be prepared; The sample to be prepared is subjected to dynamic load impact, and acoustic emission is used to monitor the generation of cracks inside the sample to be prepared to obtain an acoustic emission monitoring result; Based on the acoustic emission monitoring results, dynamic load impact and classification are performed on the rock samples to be crushed to obtain rock samples to be screened; The porosity of the rock samples to be screened is screened by three-dimensional fracture scanning to obtain rock samples with different degrees of crushing.

2. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 1 is characterized in that: The selection conditions for the rock sample to be prepared include but are not limited to uniform texture and no obvious joints or cracks.

3. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 1 is characterized in that: The method for screening the rock sample to be prepared comprises: The original pores and fractures of the rock samples were characterized by three-dimensional scanning, and the rock samples with undeveloped original pores and fractures and similar original porosity were selected as preliminary screening rock samples; The natural density and ultrasonic longitudinal wave velocity of the preliminary screened rock samples are measured respectively, and rock samples with similar natural density and ultrasonic longitudinal wave velocity are selected as samples to be prepared.

4. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 3 is characterized in that: The three-dimensional scanning method includes but is not limited to CT scanning.

5. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 1 is characterized in that: The method of performing dynamic load impact on the sample to be prepared includes but is not limited to performing dynamic load impact using a Hopkinson pressure bar with different impact air pressures.

6. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 1 is characterized in that: When the rock sample to be crushed is subjected to dynamic load impact, the impact air pressure is determined according to the crushing degree rock sample requirements and the acoustic emission crack feedback.

7. The method for preparing rock samples with different degrees of crushing by quantitative dynamic loading and three-dimensional scanning according to claim 1 is characterized in that: Methods for classifying rock samples to be crushed after dynamic load impact include: The internal cracks of the sample to be prepared are used as a criterion for judging the degree of crushing, and the degree of crushing is divided into slight crushing, moderate crushing and severe crushing according to the criterion.

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