Carbon dioxide blasting cracking hard rock test device and optimal parameter determination method

Abstract

The invention discloses a carbon dioxide blasting cracking hard rock test device and an optimal parameter determination method, and relates to the technical field of carbon dioxide blasting cracking. The device comprises a visual test cabin module, a surrounding rock fracturing effect monitoring module and an environment simulation module, the optimal parameter determination method comprises the following steps: sampling on site and sealing and storing; assembling a testing device, and preliminarily determining a blasting parameter range through single-factor analysis; designing a response surface test scheme and preparing a test sample; the sample is placed in a visual test chamber, an environment simulation module is started, and the fracturing effect is monitored; and analyzing test data, and determining optimal blasting parameters through a multiple regression equation and a response surface diagram. The method is highly suitable for practical application, the interaction among the parameters is fully considered, the process parameters can be accurately predicted and optimized, and the method has wide applicability and high preciseness.

Description

Technical Field

[0001] The invention relates to the technical field of carbon dioxide blasting cracking, and in particular to a carbon dioxide blasting cracking hard rock test device and an optimal parameter determination method. Background Art

[0002] In the field of rock blasting, although traditional explosive blasting methods are widely used, in special environments such as coal mines, the huge energy release can easily cause uncontrollable rock damage, which greatly affects its use effect. For this reason, carbon dioxide blasting and fracturing technology came into being. This technology heats the electrode through the detonator, triggering a chemical reaction in the excitation tube, causing the liquid carbon dioxide in the storage tube to rapidly gasify and expand, generating expansion pressure to break through the constant pressure energy release plate, releasing high-pressure gas directly acting on the hard rock, thereby achieving rock crushing. Carbon dioxide blasting technology has a series of advantages such as low vibration and noise, low environmental impact, no harmful gas emissions and high safety.

[0003] In order to achieve the best fracturing effect in on-site engineering construction, the optimization of carbon dioxide blasting fracturing technical parameters is crucial. However, the traditional method of determining technical parameters mainly relies on past experience and simple experiments, which is time-consuming and difficult to accurately reflect the complex interactions between parameters, resulting in insufficient adaptability and flexibility in actual engineering applications, and unable to meet the requirements of construction sites for accuracy and environmental protection. Therefore, it is urgent to invent a test device and parameter determination method that is reasonably designed, close to reality, efficient and reliable, and has a wide range of applications. Summary of the invention

[0004] In view of the above problems, the present invention discloses a carbon dioxide blasting cracking hard rock test device and an optimal parameter determination method, which can comprehensively evaluate multiple factors and their interactions through fewer experiments, achieve accurate parameter prediction and process optimization, and ensure reasonable design and high on-site fit.

[0005] According to the purpose of the present invention, a carbon dioxide blasting cracking hard rock test device is proposed, which includes a visual test chamber module, a surrounding rock cracking effect monitoring module and an environmental simulation module;

[0006] The visual test chamber module includes a visual test chamber, the upper part of which is provided with a disc end cover seal, and the bottom of which is provided with a test operation table; a fixed secondary test chamber for placing rock samples is provided inside the visual test chamber, and the fixed secondary test chamber is a three-dimensional chamber body, and its four side panels can be opened and closed;

[0007] The surrounding rock fracturing effect monitoring module includes a fracture laser scanner installed in the visual test chamber and used to monitor fractures in the rock sample in the fixed secondary test chamber;

[0008] The environmental simulation module includes a temperature-controlled humidifier for simulating environmental temperature and humidity and a confining pressure applying device for simulating environmental confining pressure; the temperature-controlled humidifier is connected to the visual test cabin through a first rubber tube; the confining pressure applying device includes a top plate and a bottom plate fixed in the secondary test cabin and a contraction hydraulic rod arranged between the top plate and the bottom plate, and the contraction hydraulic rods are at least two diagonally arranged, and the top plate presses down the rock sample under the action of the contraction hydraulic rods to apply confining pressure.

[0009] Preferably, a multi-stage hydraulic lifter for adjusting the height of the fixed secondary test cabin is also provided inside the visual test cabin; a pressure pump, a hydraulic storage tank connected to the pressure pump, a pressure display for displaying the pressure value, and a second rubber tube for connecting the hydraulic storage tank and the visual test cabin are also provided outside the visual test cabin, and one end of the second rubber tube extending into the visual test cabin is respectively connected to the multi-stage hydraulic lifter and the retractable hydraulic rod.

[0010] Preferably, electromagnetic sensors are provided on the four sides of the top plate in the fixed secondary test cabin, and electromagnetic sliding locks are provided on the inner walls of the four side plates along the moving direction of the top plate. The electromagnetic sensors and the electromagnetic sliding locks cooperate to realize the opening and closing of the side plates; the top plate and the four side plates in the fixed secondary test cabin are made of fine-pored polyurethane.

[0011] Preferably, a fixing device is provided outside the visual test cabin, the fixing device includes a first rectangular fixing plate, a second rectangular fixing plate and a fixing frame for connecting the first rectangular fixing plate and the second rectangular fixing plate, and the visual test cabin is fixedly installed in the fixing device; the disc end cover device includes a base and an openable and closable end cover, the base is fixedly connected to the first rectangular fixing plate, and the openable and closable end cover is fixedly connected to the base by a fixing buckle.

[0012] Preferably, a sealing joint is provided at the edge of the disc end cap device, and one end of the first rubber tube connected to the visual test chamber is connected to the disc end cap device through the sealing joint.

[0013] Preferably, the surrounding rock fracturing effect monitoring module further comprises a sliding guide rail, the sliding guide rail is installed on the inner wall of the visual test chamber along the circumference of the visual test chamber, and the crack laser scanner is installed on the sliding guide rail.

[0014] The present invention further discloses a method for determining optimal parameters for carbon dioxide blasting cracking hard rock using the above-mentioned carbon dioxide blasting cracking hard rock test device, comprising the following steps:

[0015] Step 1: Drill multiple groups of rock samples on site and store them in sealed containers. Some of the samples are used for physical and mechanical parameter testing, and the rest are stored at room temperature for subsequent processing.

[0016] Step 2: Combine multiple influencing factors to select multiple groups of different CO2 blasting parameters, and use numerical simulation software to perform single factor analysis based on the rock physical and mechanical properties obtained in step 1, preliminarily determine the range of blasting parameters, and design a response surface test plan;

[0017] Step 3: Connect the test device, start the pressure pump to apply equivalent confining pressure, start the temperature-controlled humidifier to adjust the temperature and humidity in the visual test chamber, turn on the crack laser scanner to calibrate and obtain initial data, perform overall calibration of the instrument, and turn off the instrument after calibration;

[0018] Step 4: Drill holes of specified specifications on the rock samples prepared in different test schemes, insert the carbon dioxide fracturing tube, place the rock sample on the fixed secondary test chamber in the visual test chamber, adjust the position and start the equipment, control the temperature, humidity and confining pressure, and record the number of fractures in the rock sample;

[0019] Step 5: Based on the test results in step 4, analyze the test result data;

[0020] Step 6: Based on the analysis results of step 5, a response surface analysis is performed to determine the optimal parameter combination through multiple regression equations and response surface plots, and finally determine the optimal parameters for carbon dioxide explosion.

[0021] Preferably, in step six, the response surface analysis method is: first, fit the multivariate quadratic response surface regression equation, analyze the variance of the response variable and analyze the significance of each factor; then, perform residual diagnosis, when the residual is "S" shaped or "reverse S" shaped with respect to the independent variable, it means that the higher-order term of x needs to be added, otherwise it is not needed; if there is an insignificant term, it is necessary to delete the term and refit the model; finally, according to the above-mentioned multivariate regression equation, draw a graph to analyze the relationship between the independent variable and the dependent variable, and obtain the response surface diagram of the regression equation. Through the analysis of the response surface, the level combination of the optimal factors, that is, the optimal parameter combination of carbon dioxide blasting, can be intuitively and clearly determined.

[0022] Preferably, in step 2, the multiple influencing factors include borehole diameter, hole spacing, hole depth, arrangement method, pressure relief method, ambient temperature, ambient humidity, pressure measurement coefficient, and coal rock type in the rock sample.

[0023] Preferably, the response surface experimental design and response surface data analysis are both performed using Design-Expert 13.0 software.

[0024] Compared with the prior art, the carbon dioxide blasting cracking hard rock test device and the optimal parameter determination method disclosed in the present invention have the following advantages:

[0025] (1) Based on a relatively small number of tests, the present invention can comprehensively evaluate multiple factors and their interactions, achieve accurate parameter prediction and process optimization, and ensure reasonable design and high on-site fit.

[0026] (2) The test device of the present invention adopts a modular design, has a simple structure, is easy to assemble, has strong practicality and flexibility, and is suitable for a variety of test scenarios.

[0027] (3) The present invention significantly reduces the test cost by adopting the response surface method for testing, while improving the accuracy and efficiency of parameter optimization, so that the optimal blasting parameter combination can be obtained more quickly in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a three-dimensional diagram of the carbon dioxide blasting and cracking hard rock test device.

[0030] Figure 2 This is the front view of the carbon dioxide blasting and cracking hard rock test device.

[0031] Figure 3 This is a three-dimensional diagram of the fixed secondary test chamber.

[0032] Figure 4 This is a response surface diagram of the influencing factors A and C when analyzing the interaction in an embodiment of the present invention.

[0033] Figure 5 This is a response surface diagram of influencing factors A and B when analyzing the interaction in an embodiment of the present invention.

[0034] Figure 6 This is a response surface diagram of the influencing factors B and C when analyzing the interaction in an embodiment of the present invention.

[0035] In the figure: 1-visual test cabin; 2-first rectangular fixed plate; 3-disc end cover; 4-fixed skeleton; 5-fixed bolts; 6-multi-stage hydraulic lifter; 7-fixed secondary test cabin; 8-crack laser scanner; 9-sliding guide rail; 10-confining pressure application adjustment starter; 11-multi-stage hydraulic lifting adjustment starter; 12-second rectangular fixed plate; 13-test operating table; 14-pressurization pump; 15-fixed base; 16-pressurization display; 17-spare pressurization display; 18-hydraulic storage tank; 19-second rubber tube; 20-temperature controlled humidifier; 21-first rubber tube; 22-sealing joint; 23-fixed buckle; 24-parameter display central control; 25-bottom closed joint; 26-top plate; 27-side plate; 28-retractable hydraulic rod; 29-electromagnetic sliding lock; 30-electromagnetic sensor; 31-rock sample. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention is briefly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 1-Figure 6 The preferred embodiments of the present invention are shown and analyzed in detail.

[0038] like Figure 1 , 2 A carbon dioxide blasting cracking hard rock test device is shown, comprising a visual test chamber module, a surrounding rock cracking effect monitoring module and an environmental simulation module.

[0039] The visual test chamber module includes a cylindrical visual test chamber 1, which is a cylindrical transparent chamber integrally die-casted from polycarbonate, ensuring the clarity of test observation and the durability of the equipment. A disc end cover 3 is provided on the upper part of the visual test chamber 1 for sealing, and a test operating table 13 is installed on the bottom. A fixing device is provided outside the visual test chamber 1, and the fixing device includes a first rectangular fixing plate 2 and a second rectangular fixing plate 12 arranged up and down, and four fixing frames 4 for connecting the first rectangular fixing plate 2 and the second rectangular fixing plate 12, and the fixing frames 4 are fixedly connected to the first rectangular fixing plate 2 and the second rectangular fixing plate 12 by fixing bolts 5. The visual test chamber 1 is fixedly installed in the fixing device. The disc end cover 3 includes a base and an openable and closable end cover, wherein the base is welded to the first rectangular fixing plate 2, and the openable and closable end cover is fixedly connected to the base by four fixing buckles 23 arranged in a cross orientation, and the openable and closable end cover can be opened by pressing the fixing buckle 23. An annular rubber gasket is provided at the edge of the openable and closable end cover to effectively increase the sealing of the visual test chamber 1. The test operating table 13 is provided with a confining pressure application adjustment starter 10 for adjusting the confining pressure, a multi-stage hydraulic lifting adjustment starter 11 for adjusting the multi-stage hydraulic lifter 6, and a parameter display central control 24. The parameter display central control 24 can adjust the power and scanning direction of the fracture laser scanner 8, and can display the pressure, temperature, humidity and other related data in the test chamber in real time and intuitively. A fixed secondary test chamber 7 for placing rock samples 31 and a multi-stage hydraulic lifter 6 are provided inside the visual test chamber 1. Figure 3 As shown, the fixed secondary test chamber 7 is a three-dimensional chamber, including a top plate 26, a bottom plate and four side plates 27, and the four side plates 27 can be opened and closed. Specifically, two retractable hydraulic rods 28 are arranged between the top plate 26 and the bottom plate, and the two retractable hydraulic rods 28 are arranged diagonally. The top plate 26 can move up and down driven by the two retractable hydraulic rods 28, and press down the rock sample 31 to simulate the application of confining pressure. Electromagnetic sensors 30 are arranged on the four sides of the top plate 26, and electromagnetic sliding locks 29 are arranged on the inner walls of the four side plates 27 along the moving direction of the top plate 26. The electromagnetic sensors 30 cooperate with the electromagnetic sliding locks 29 to realize the remote opening and closing of the side plates 27, so as to facilitate the scanning of the rock sample 31 by the fracture laser scanner 8 after the rock sample 31 is fractured. The top plate 26 and four side plates 27 in the fixed secondary test chamber 7 are made of fine-porous polyurethane to prevent the damage of the fracture laser scanner 8 caused by the splash of fine rock debris that may be generated after blasting, and to ensure the uniformity of temperature and humidity between the fixed secondary test chamber 7 and the visual test chamber 1. The multi-stage hydraulic lifter 6 is arranged under the fixed secondary test chamber 7 to adjust the height of the fixed secondary test chamber 7. After the hard rock is fractured, the side plates 27 of the fixed secondary test chamber 7 can be opened by remote control, and the fixed secondary test chamber 7 can be adjusted to a suitable height by adjusting the multi-stage hydraulic lifter 6, so that the fracture laser scanner 8 can scan the fracture.

[0040] The surrounding rock fracturing effect monitoring module includes a fracture laser scanner 8 installed in the visual test chamber 1 for monitoring fractures of the rock sample 31 on the fixed secondary test chamber 7, and a sliding guide rail 9 for installing the fracture laser scanner 8. The sliding guide rail 9 is installed in the middle of the inner wall of the visual test chamber 1 along the circumference of the visual test chamber 1. The sliding guide rail 9 is an annular guide rail and the outer side is fixed to the inner wall of the visual test chamber 1 by hot melt adhesive. The fracture laser scanner 8 is installed on the sliding guide rail 9, and the scanning lens faces the direction of the fixed secondary test chamber 7. It can scan the rock sample 31 in real time at 360° with the sliding guide rail 9 to accurately record the fracturing situation.

[0041] The environmental simulation module includes a temperature-controlled humidifier 20 for simulating environmental temperature and humidity and a confining pressure applying device for simulating environmental confining pressure. The temperature-controlled humidifier 20 is connected to the visual test cabin 1 through a first rubber tube 21, and a sealing joint 22 is provided at the edge of the disc end cover device 3. One end of the first rubber tube 21 connected to the visual test cabin 1 is connected to the disc end cover device 3 through the sealing joint 22. The confining pressure applying device is composed of a top plate 26 and a bottom plate fixed in the secondary test cabin 7, and a retractable hydraulic rod 28 arranged between the top plate 26 and the bottom plate. The top plate 26 presses down the rock sample 31 under the action of the retractable hydraulic rod 28 to apply confining pressure. A pressure pump 14, a hydraulic storage tank 18 connected to the pressure pump 14, a pressure display 16 for displaying the pressure value, and a second rubber tube 19 for connecting the hydraulic storage tank 18 and the visual test cabin 1 are also provided outside the visual test cabin 1. One end of the second rubber tube 19 extending into the visual test cabin 1 is respectively connected to the multi-stage hydraulic lifter 6 and the retractable hydraulic rod 28. The connection between the second rubber tube 19 and the visual test cabin 1 is provided with a bilge sealed joint 25 for transfer. The booster pump 14 is fixed by a fixed base 15 to maintain the stability of the equipment. When the booster pump 14 is running, the booster display 16 that displays the booster value can display the real-time booster status and booster value. The standby booster display 17 is used as a spare part to maintain the stability of the equipment operation. The hydraulic storage tank 18 is connected to the booster pump 14 at the upper part through the rear of the fixed three-way pipe and connected to the booster display 16. The hydraulic storage tank is used to drive and recover hydraulic oil. The booster pump 14 and the hydraulic storage tank are set to provide power for the retracting hydraulic rod 28 and the multi-stage hydraulic lifter 6 to drive the two to move.

[0042] The present invention further discloses a method for determining optimal parameters for carbon dioxide blasting cracking hard rock using the above-mentioned carbon dioxide blasting cracking hard rock test device, comprising the following steps:

[0043] Step 1: Drill multiple groups of rock samples 31 from the site and directly wax seal them. Some of the rock samples 31 are sent to the laboratory for physical and mechanical parameter testing, and the rest are stored at room temperature for subsequent laboratory processing;

[0044] Step 2: Combine multiple influencing factors, select multiple groups of carbon dioxide blasting parameters of different schemes, and combine the rock physical and mechanical properties obtained in step 1 to use numerical simulation software such as Flac3d and PFC to preliminarily obtain the optimal blasting parameter range through single factor analysis. Under normal conditions, the influencing factors that can be considered include hole diameter, hole spacing, hole depth, arrangement method, pressure relief method, ambient temperature, ambient humidity, pressure measurement coefficient, coal rock type, etc. In order to facilitate demonstration, this embodiment selects FLAC3D 7.0 as the single factor test software, selects hole spacing, hole depth, and hole diameter as the main influencing factors, and obtains the optimal parameter range according to the numerical simulation results as follows:

[0045] Table 1 Optimal parameter range

[0046]

[0047] On the basis of the preliminary acquisition of the optimal blasting parameter range, the response surface test scheme was designed using Design-Expert 13.0 software. According to the Box-Behnken central combination design principle, the hole diameter, hole spacing and hole depth were selected as the response factors, and the proportion of cracks in rock sample 31 was selected as the response value. A total of 17 test combinations with three factors and three levels were designed. The test settings are as follows:

[0048] Table 2 Factor level table

[0049]

[0050] Table 3 Box-Behnken response surface experimental design

[0051]

[0052]

[0053] Step 3: First, prepare the corresponding rock sample 31 specimen for the next test according to the Box-Behnken response surface test design scheme in step 2. Secondly, perform equipment parameter initialization calibration: start the booster pump 14 simulating the ambient pressure to apply equivalent ambient pressure, and simultaneously start the temperature-controlled humidifier 20 to make the temperature and humidity of the test chamber reach the specified values, turn on the rock fracture laser scanner 8, calibrate the determination coefficient, obtain the initial value, and turn off the instrument after the calibration is completed.

[0054] Step 4: Drill a hole on the corresponding rock sample 31 prepared in different test schemes and put in a carbon dioxide fracturing tube, then put the whole into the fixed secondary test chamber 7 inside the visual test chamber 1 to start the test, turn on the temperature control humidifier 20 to make the temperature and humidity in the visual test chamber 1 reach the specified value, turn on the confining pressure boosting pump 14 to reach the specified value, and at the same time turn on the rock fracture laser scanner to scan and record the number of fractures in the rock sample 31 after fracturing under different test schemes, and then normalize the number of fractures in the rock sample 31 after fracturing under different test schemes to obtain the fracture proportion LX under different test schemes. i (i is the experiment number).

[0055] Step 5: Based on the test results in step 4, the test result data is analyzed and the Box-Behnken response surface test results are determined as follows:

[0056] Table 4 Box-Behnken response surface test results

[0057]

[0058] Step six: Based on the experimental results in step five, use Design expert 13.0 software to perform response surface data analysis. The first step is to fit the multivariate quadratic response surface regression equation, analyze the variance of the response variable and analyze the significance of each factor. The second step is to perform residual diagnosis. When the residual is "S" shaped or "reverse S" shaped with respect to the independent variable, it means that the higher-order terms of x need to be added, otherwise it is not necessary. In addition, if there are insignificant terms, it is necessary to delete the terms and refit the model. The fourth step is to use Design expert 13.0 software again to draw and analyze the relationship between the independent variables and the dependent variables according to the above multivariate regression equation, and obtain the response surface diagram of the regression equation. Through the analysis of the response surface, the level combination of the optimal factors can be intuitively and clearly determined, that is, the optimal parameter combination for carbon dioxide blasting. The response surface diagram of the regression equation in this example is shown as follows. Figure 4-6 shown.

[0059] The above description of the disclosed embodiments enables those skilled in the art to implement and use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A carbon dioxide blasting cracking hard rock test device, characterized in that: It includes visual test chamber module, surrounding rock fracturing effect monitoring module and environmental simulation module; The visual test chamber module comprises a visual test chamber (1), the upper part of the visual test chamber (1) is provided with a disc end cover (3) for sealing, and the bottom is provided with a test operation table (13); a fixed secondary test chamber (7) for placing a rock sample (31) is provided inside the visual test chamber (1), and the fixed secondary test chamber (7) is a three-dimensional chamber body, and its four side panels (27) can be opened and closed; The surrounding rock fracture effect monitoring module comprises a fracture laser scanner (8) installed in the visual test chamber (1) and used for monitoring fractures of the rock sample (31) in the fixed secondary test chamber (7); The environmental simulation module comprises a temperature-controlled humidifier (20) for simulating environmental temperature and humidity, and a confining pressure applying device for simulating environmental confining pressure; the temperature-controlled humidifier (20) is connected to the visual test chamber (1) via a first rubber tube (21); the confining pressure applying device comprises a top plate (26) and a bottom plate fixed in the secondary test chamber (7), and a retractable hydraulic rod (28) arranged between the top plate (26) and the bottom plate, wherein at least two retractable hydraulic rods (28) are arranged diagonally, and the top plate (26) presses down the rock sample (31) under the action of the retractable hydraulic rods (28) to apply confining pressure.

2. A carbon dioxide blasting cracking hard rock test device according to claim 1, characterized in that: The visual test cabin (1) is also provided with a multi-stage hydraulic lifter (6) for adjusting the height of the fixed secondary test cabin (7); the visual test cabin (1) is also provided with a pressure pump (14), a hydraulic storage tank (18) connected to the pressure pump (14), a pressure display (16) for displaying a pressure value, and a second rubber tube (19) for connecting the hydraulic storage tank (18) and the visual test cabin (1); one end of the second rubber tube (19) extending into the visual test cabin (1) is respectively connected to the multi-stage hydraulic lifter (6) and the retractable hydraulic rod (28).

3. A carbon dioxide blasting cracking hard rock test device according to claim 1, characterized in that: Electromagnetic inductors (30) are arranged on the four side edges of the top plate (26) in the fixed secondary test cabin (7); electromagnetic sliding locks (29) are arranged on the inner walls of the four side plates (27) along the moving direction of the top plate (26); the electromagnetic inductors (30) cooperate with the electromagnetic sliding locks (29) to realize the opening and closing of the side plates (27); the top plate (26) and the four side plates (27) in the fixed secondary test cabin (7) are all made of fine-pored polyurethane.

4. A carbon dioxide blasting cracking hard rock test device according to claim 1, characterized in that: A fixing device is arranged outside the visual test chamber (1), the fixing device comprising a first rectangular fixing plate (2), a second rectangular fixing plate (12) and a fixing frame (4) for connecting the first rectangular fixing plate (2) and the second rectangular fixing plate (12), and the visual test chamber (1) is fixedly installed in the fixing device; the disc end cover device (3) comprises a base and an openable and closable end cover, the base is fixedly connected to the first rectangular fixing plate (2), and the openable and closable end cover is fixedly connected to the base via a fixing buckle (23).

5. A carbon dioxide blasting cracking hard rock test device according to claim 1, characterized in that: A sealing joint (22) is provided at the edge of the disc end cover device (3), and one end of the first rubber tube (21) connected to the visual test chamber (1) is connected to the disc end cover device (3) through the sealing joint (22).

6. A carbon dioxide blasting cracking hard rock test device according to claim 1, characterized in that: The surrounding rock fracture effect monitoring module further comprises a sliding guide rail (9), wherein the sliding guide rail (9) is installed on the inner wall of the visual test chamber (1) along the circumference of the visual test chamber (1), and the crack laser scanner (8) is installed on the sliding guide rail (9).

7. A method for determining optimal parameters for carbon dioxide blasting hard rock cracking using the carbon dioxide blasting hard rock cracking test device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Drill multiple groups of rock samples (31) on site and directly seal and store them, some of the rock samples (31) are used for physical and mechanical parameter testing, and the rest are stored at room temperature for subsequent processing; Step 2: Combine multiple influencing factors to select multiple groups of different CO2 blasting parameters, and use numerical simulation software to perform single factor analysis based on the rock physical and mechanical properties obtained in step 1, preliminarily determine the range of blasting parameters, and design a response surface test plan; Step 3: Connect the test device, start the pressure pump (14) to apply equivalent confining pressure, and start the temperature-controlled humidifier (20) to adjust the temperature and humidity in the visual test chamber (1). Turn on the crack laser scanner (8) to calibrate and obtain initial data, perform overall calibration of the instrument, and turn off the instrument after calibration. Step 4: Drill holes of specified specifications on the rock samples (31) prepared in different test schemes, insert the carbon dioxide fracturing tube, place the rock sample (31) on the fixed secondary test chamber (7) in the visual test chamber (1), adjust the position and start the equipment, control the temperature, humidity and confining pressure, and record the number of fracturing cracks in the rock sample (31); Step 5: Based on the test results in step 4, analyze the test result data; Step 6: Based on the analysis results of step 5, a response surface analysis is performed to determine the optimal parameter combination through multiple regression equations and response surface plots, and finally determine the optimal parameters for carbon dioxide explosion.

8. The method according to claim 7, characterized in that In step six, the response surface analysis method is: first, fit the multivariate quadratic response surface regression equation, analyze the variance of the response variable and analyze the significance of each factor; then, perform residual diagnosis. When the residual is "S"-shaped or "reverse S"-shaped with respect to the independent variable, it means that the higher-order terms of x need to be added, otherwise it is not necessary; if there are insignificant terms, the terms need to be deleted and the model needs to be refitted; finally, according to the above multivariate regression equation, draw a graph to analyze the relationship between the independent variable and the dependent variable, and obtain the response surface diagram of the regression equation. Through the analysis of the response surface, the level combination of the optimal factors, that is, the optimal parameter combination of carbon dioxide blasting, can be intuitively and clearly determined.

9. The method according to claim 7, characterized in that: In step 2, the various influencing factors include the borehole diameter, hole spacing, hole depth, arrangement method, pressure relief method, ambient temperature, ambient humidity, pressure measurement coefficient, and coal rock type in the rock sample (31).

10. The method according to claim 7, characterized in that Design-Expert 13.0 software was used for both response surface experimental design and response surface data analysis.

Images