A supercritical CO2 phase change energy testing method

Abstract

The invention discloses a supercritical CO 2 The phase change energy gathering test method comprises the following steps: assembling a test device, the test device comprising a sleeve, a clamp and an industrial camera; pasting a plurality of strain components on the sleeve wall, extending a fracturing tube into the sleeve, and fixing the fracturing tube; controlling the clamp to clamp the sleeve through a control module, and recording the clamping force of the clamp; detonating the fracturing tube, and using the strain component to collect and record the strain data of the sleeve in real time, and using the industrial camera to collect and record the deformation process of the sleeve; calculating the peak stress of the same sleeve at different parts according to the data collected by the strain component, and drawing a stress distribution diagram of the sleeve; replacing sleeves of different diameters, and conducting a plurality of groups of tests, and drawing a stress distribution diagram according to the stress distribution obtained from each group of tests. The present invention can improve the safety and accuracy of data collection, and is convenient for intuitively reflecting the energy gathering effect of supercritical CO2 phase change fracturing.

Description

Technical Field

[0001] The invention relates to the technical field of industrial automatic detection devices, and in particular to a supercritical CO2 phase change energy gathering test method. Background Art

[0002] Traditional blasting methods such as explosives often produce a large amount of toxic gases, dust and other pollutants during the blasting process, which pose a serious threat to the environment and human health. Supercritical CO2 phase change is a new type of blasting technology. This technology uses a heating tube (or fracturing tube) to quickly change the liquid-gas phase of liquid CO2 at a certain pressure and temperature, and the volume expands 600 times instantly, thereby generating a strong physical pressure (above 200MPa). In contrast, CO2 itself is non-toxic and harmless, and will not produce any harmful substances after blasting, and will not pollute the environment, which is completely in line with the modern society's pursuit of green environmental protection.

[0003] Supercritical CO2 phase change is now often used in a variety of projects such as foundation pit excavation, coal seam permeability enhancement, tunneling, and mining. This technology still has the following problems in blasting application and experimental research:

[0004] The fracturing pipe has an obvious energy gathering effect (hereinafter referred to as the energy gathering effect) due to its own structural reasons. According to current research, the supercritical CO2 phase change-induced shock wave is often regarded as a cylindrical shape, which cannot reflect its unique energy gathering state from an angle, and there is a lack of experimental equipment that can directly observe the rock strain caused by the energy gathering effect. Secondly, different borehole diameters will change the coupling coefficient of the blasting, thereby affecting the degree of energy gathering.

[0005] The existing technology has not yet explored the law of the energy-gathering effect, which has practical application significance. Limited by theoretical research, this technology often fails to consider the influence of energy-gathering characteristics in practical applications, resulting in the inability to improve blasting efficiency. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a supercritical CO2 phase change energy gathering test method, which solves the problem in the prior art that there is a lack of a test device that can intuitively observe the energy gathering effect strain and can consider the influence of the drilling depth.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A supercritical CO2 phase change energy testing method is provided, which comprises the following steps:

[0009] S1. Assemble a test device, the test device includes a sleeve and a clamp, and an industrial camera is placed on one side of the sleeve;

[0010] S2, affixing several strain components on the sleeve wall, inserting the fracturing tube into the sleeve, and fixing the fracturing tube;

[0011] S3, controlling the clamping sleeve of the clamp through the control module, and recording the clamping force of the clamp;

[0012] S4, detonating the cracking tube, and using a strain component to collect and record the strain data of the sleeve in real time, and using an industrial camera to collect and record the deformation process of the sleeve;

[0013] S5. Calculate the peak stress of the same sleeve at different positions according to the data collected by the strain component, and draw a stress distribution diagram of the sleeve;

[0014] S6. Replace sleeves with different diameters, repeat steps S2-S5, conduct several groups of tests, and draw stress distribution diagrams reflecting the degree of energy concentration under different coupling conditions based on the stress distribution obtained from each group of tests.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention replaces the blasting object rock commonly used by researchers with a metal sleeve, and transforms the problem of rock blasting into the problem of compression and deformation of a thin-walled cylinder, thereby establishing a research model. Due to the structural characteristics of the metal cylinder, its destruction process is slower than that of the rock, with a fairly long observation time, and more data about the blasting process can be recorded.

[0017] 2. The sleeve will not break into pieces like a rock, but will leave a clear failure mode. By collecting and recording the strain parameters of the blasting metal tube through the strain gauge, its stress distribution can be calculated, and then a stress distribution curve can be drawn to intuitively reflect the energy-gathering effect from an angle. Replacing sleeves of different diameters is equivalent to changing the coupling coefficient of the blasting. The degree of energy-gathering under different coupling coefficients can be explored through test data and calculations.

[0018] Preferably, the strain components are evenly arranged along the length direction of the sleeve, and one strain component includes a plurality of strain gauges evenly distributed circumferentially along the sleeve wall.

[0019] Step S5 further comprises:

[0020] S51, strain data recorded by strain gauge is ε 1(1) ,ε 1(2) ,...,ε 2(1) ,...,ε i(n) ,...,ε I(N) , calculate the stress value of each part of the sleeve respectively:

[0021]

[0022] Where i is the i-th layer of the strain assembly; n is the n-th strain gauge in the strain assembly; I is the total number of layers of the strain assembly, and N is the total number of strain gauges in the strain assembly; ε i(n) is the strain data collected by the nth strain gauge in the i-th layer strain component; σ i(n) is the stress value at the corresponding position of the nth strain gauge in the i-th layer strain assembly on the sleeve wall;

[0023] S52, establishing a polar coordinate system with the center of the sleeve cross section as the origin;

[0024] Among them, the polar diameter represents the magnitude of the stress value, and the polar angle represents the angle passed by the line from the reference axis to the origin and a certain point in a counterclockwise rotation;

[0025] S53, drawing a stress distribution curve diagram on a polar coordinate system based on the distribution points of the strain gauges in the first layer strain assembly and the calculated stress values;

[0026] S54, according to the method of step S53, draw the stress distribution curve diagrams of the 2nd to 1st layers in sequence in the same polar coordinate system.

[0027] Step S6 further comprises:

[0028] S61, calculating the force exerted on the sleeve by the shock wave of the cracked pipe, establishing a polar coordinate system, and drawing a stress distribution diagram of the sleeve wall in the polar coordinate system according to the calculation results;

[0029] S62. Replace sleeves with different diameters to perform burst tests under different coupling conditions, and record strain data collected by the strain gauges;

[0030] S63. Based on the strain data collected by the strain gauge, the stress distribution diagrams of the sleeve wall under different coupling conditions are drawn on the polar coordinate system in S61.

[0031] Step S61 further includes:

[0032] S611. Calculate the theoretical pressure value of the blasting on the sleeve wall under the coupled blasting condition:

[0033]

[0034] Among them, P b is the theoretical bursting pressure of the fractured pipe; C p and D are the shock wave velocity and detonation velocity in the sleeve respectively; ρ and ρ0 are the density of the sleeve and carbon dioxide respectively; P2 is the theoretical pressure value of the explosion on the sleeve wall under coupling conditions;

[0035] S612. Calculate the theoretical pressure value of the blasting on the sleeve wall under uncoupled conditions:

[0036]

[0037] Among them, α is the decay exponent; is the proportional distance; P w is the theoretical pressure value of the blasting on the sleeve wall under uncoupled conditions;

[0038] S613. Calculate the theoretical pressure value on the sleeve wall:

[0039]

[0040] Among them, a r P is the radial clamping force of the clamp on the sleeve; e is the theoretical pressure value on the sleeve wall;

[0041] S614, based on the distribution points of the strain gauges in the i-th layer strain assembly and the calculated P e Based on the value, the stress distribution curve under different sleeve diameters is drawn on the polar coordinate system.

[0042] Furthermore, the test device also includes a test box, and the sleeve and the clamp are both arranged inside the test box; the test box includes a rectangular frame structure formed by angle steel, and a bottom plate and side panels fixed on the angle steel, and the top plate is detachably connected to the angle steel through a fixing piece; an industrial camera electrically connected to the control module is arranged on one side of the test box, and the side of the test box close to the industrial camera is a transparent plate; a fixing column with an external thread is fixedly connected to the bottom plate of the test box, the fixing column passes through the bottom plate of the sleeve and extends into the interior of the sleeve, and a threaded hole matching the fixing column is opened at the bottom of the fracturing tube, and the fixing column is threadedly connected to the fracturing tube during the test.

[0043] Furthermore, the clamp includes two clamping cylinders arranged opposite to each other, and a clamping hole penetrating the clamping cylinder is opened on the edge of the clamping cylinder, and the cross-section of the clamping hole is semi-elliptical; a push rod is fixedly connected to the side of the clamping cylinder away from the clamping hole, and the push rod is connected to the driver A, and the driver A is electrically connected to the control module.

[0044] Furthermore, two opposite sides of the clamping cylinder are open ends, and two sides of the open ends are covered with elastic diaphragms, which are sealed and connected to the clamping cylinder;

[0045] Furthermore, a piston is provided inside the clamping cylinder to divide the internal cavity into two independent chambers. The chamber close to the elastic diaphragm is a working chamber filled with liquid. A push rod fixedly connected to the piston extends out of the other chamber of the clamping cylinder and is connected to a driver B. The driver B is electrically connected to a control module. The strain gauges are all adhered to the inner wall of the sleeve, and the position where the strain gauges are adhered does not exceed the range of the elastic diaphragm wrapping the sleeve.

[0046] Furthermore, a pressure gauge is provided on the clamping cylinder. When the pressure gauge displays a reading When , the control module controls the driver B to close;

[0047] Among them, π is the pi; r is the outer radius of the sleeve; L is the length of the elastic diaphragm wrapped around the sleeve; P is the reading of the pressure gauge.

[0048] Furthermore, a through hole is provided on the top plate of the test box for the fracturing tube to extend into; the test device also includes a limit support, which is fixed to the outer wall of the fracturing tube and contacts the lower surface of the top plate when in use; the surface area of ​​the limit support is larger than the cross-sectional area of ​​the through hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the supercritical CO2 phase change energy testing method;

[0050] Figure 2 It is a top view when the clamp is not clamping the sleeve in the non-test state;

[0051] Figure 3 This is a top view of the cross section when the clamp is clamping the sleeve during the test;

[0052] Figure 4 This is a front cross-sectional view of the clamp clamping the sleeve during the test;

[0053] Figure 5 It is a schematic diagram of the arrangement of strain gauges on the inner wall of the sleeve;

[0054] Figure 6 A schematic diagram showing the fixed connection between the fracture-causing pipe and the limiting support;

[0055] Figure 7 It is the structural diagram of the test box;

[0056] Figure 8 This is a schematic diagram of the top of the clamping hole contacting the sleeve during the test;

[0057] Fig. 9 Flow chart of the test method;

[0058] Fig.10 Stress distribution diagram of monitoring points in different layers at different angles;

[0059] Fig.11 Stress distribution diagram of sleeves with different diameters.

[0060] Among them, 1. test box; 11. top plate; 12. through hole; 13. fixing part; 14. angle steel; 15. transparent plate; 2. cracking tube; 3. limit support; 4. sleeve; 5. strain gauge; 6. industrial camera; 7. clamp; 71. clamping cylinder; 72. clamping hole; 73. push rod; 74. piston; 75. elastic diaphragm; 76. push rod; 77. working chamber; 8. fixing column. DETAILED DESCRIPTION

[0061] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0062] like Fig. 9 As shown, the supercritical CO2 phase change energy testing method of this scheme includes:

[0063] S1. Assemble the test device, which includes a sleeve 4 and a clamp 7. The sleeve 4 is a metal cylinder with openings at both ends. An industrial camera 6 is placed on one side of the sleeve 4. The test device also includes a test box 1 with a hollow interior. The sleeve 4 and the clamp 7 for clamping the sleeve 4 are both arranged inside the test box 1.

[0064] S2, a plurality of strain assemblies are pasted on the wall of the sleeve 4, and the strain assemblies and the clamp 7 are electrically connected to the control module; the fracturing tube 2 is inserted into the sleeve 4 to fix the fracturing tube 2; the strain assemblies are evenly arranged along the length direction of the sleeve 4, and one strain assembly includes a plurality of strain gauges 5 evenly distributed along the circumferential direction of the wall of the sleeve 4;

[0065] S3, controlling the clamp 7 to clamp the sleeve 4 through the control module, and recording the clamping force of the clamp 7;

[0066] S4, detonating the cracking tube 2, during the test, the strain component collects and records the strain data of the sleeve 4 in real time, and the industrial camera 6 collects and records the deformation process of the sleeve 4;

[0067] S5. Calculate the peak stress of the same sleeve 4 at different positions according to the data collected by the strain assembly, and draw a stress distribution diagram of the sleeve 4 to intuitively reflect the energy accumulation degree of supercritical CO2 phase change cracking;

[0068] S6. Replace the sleeve 4 with a different diameter, repeat steps S2-S5, conduct several groups of tests, and draw a stress distribution diagram reflecting the degree of energy concentration under different coupling conditions according to the stress distribution obtained from each group of tests.

[0069] The traditional CO2 blasting test device is as follows: a strain gauge 5 is fixedly connected to the rock wall, and a hole is drilled in the rock to allow the fracturing tube 2 to be inserted. After the fracturing tube 2 is placed in the drill hole, the fracturing tube 2 is detonated to blast the rock. Strain data is collected through the strain gauge 5 to explore the stress field during the blasting. However, the strength of the rock is low, and the rock will break quickly under the action of the shock wave. Therefore, researchers can only use the strain data collected before the rock breaks as effective data.

[0070] This means that the time window for test data collection is extremely short, and the effective strain data that can be collected is very limited. This fast process may not be able to fully capture the strain data or other data of the entire process of rock from elastic deformation to plastic deformation and final fracture, thus limiting the in-depth analysis of the strain-stress relationship.

[0071] Secondly, since the rock will experience severe stress and deformation during the blasting process, the strain gauge 5 attached to the rock wall is likely to fall off or be damaged during the blasting process, resulting in data loss or distortion. This not only affects the integrity of the data, but may also introduce errors, making the analysis results unreliable.

[0072] The present invention replaces the blasting object rock commonly used by researchers with a metal sleeve 4 with two ends open, and transforms the problem of rock blasting into the problem of compression and deformation of a thin-walled cylinder, thereby establishing a research model. Due to the structural characteristics of the metal sleeve 4, its destruction process is slower than that of the rock, with a relatively long observation time, and more data about the blasting process can be recorded.

[0073] The sleeve 4 will not break into pieces like a rock, but will leave a clear failure mode. By collecting and recording the strain parameters of the blasting metal tube through the strain gauge 5, its stress distribution can be calculated, and then a stress distribution curve can be drawn to intuitively reflect the energy-gathering effect from an angle. Replacing the sleeve 4 with different diameters is equivalent to changing the coupling coefficient of the blasting. The degree of energy-gathering under different coupling coefficients can be explored through test data and calculation.

[0074] Step S3 includes the following steps:

[0075] S31, connecting the detonation wire to the two electrodes of the filling head of the fracturing tube 2, and connecting the signal wires of several strain components and the control module;

[0076] S32, the strain component transmits an electrical signal for collecting data to the control module in real time, and at the same time turns on the industrial camera 6 to record the deformation state of the sleeve 4;

[0077] The industrial camera 6 may be a Basler acA1600 industrial camera, the lens of which may be a TAWOV lens with a focal length of 25 mm, a resolution of 1624×1236 pixels, and a pixel size of 3.45 μm.

[0078] S33, connecting the detonator and the detonating wire, turning on the detonator and charging it to the detonation voltage, releasing the voltage to stimulate the fracture tube 2 to complete the detonation;

[0079] S34. Stop data collection.

[0080] Step S5 further comprises:

[0081] S51, strain data recorded by strain gauge 5 is ε 1(1) ,ε 1(2) ,...,ε 2(1) ,...,ε i(n) ,...,ε I(N) , calculate the stress values ​​of various parts of sleeve 4 respectively:

[0082]

[0083] Where i is the i-th layer of the strain assembly; n is the n-th strain gauge in the strain assembly; I is the total number of layers of the strain assembly, and N is the total number of strain gauges in the strain assembly; ε i(n) is the strain data collected by the nth strain gauge in the i-th layer strain component; σ i(n) is the stress value at the corresponding position of the nth strain gauge in the i-th layer strain assembly on the sleeve wall;

[0084] S52, establishing a polar coordinate system with the center of the cross section of the sleeve 4 as the origin;

[0085] Among them, the polar diameter represents the magnitude of the stress value, and the polar angle represents the angle passed by the line from the reference axis to the origin and a certain point in a counterclockwise rotation;

[0086] S53, drawing a stress distribution curve diagram on a polar coordinate system based on the distribution points of the strain gauges in the first layer strain assembly and the calculated stress values;

[0087] S54, in accordance with the method of step S53, the stress distribution curves of the 2nd to 1st layers are drawn in sequence in the same polar coordinate system, and the stress distribution curves are compared with each other to observe the energy concentration effect and degree of different layers.

[0088] In one embodiment, the fracturing tube 2 and the sleeve 4 are selected to start the test, and the peak strain and peak stress of the monitoring points of the 1st to 4th layers on the sleeve 4 (i.e., the points where the strain gauges 5 are attached) are counted, and the following can be plotted: Fig.10 The stress distribution curve shown is used to intuitively observe the stress concentration of each layer.

[0089] Fig.10The direction pointed by the red arrow is the jet direction of supercritical CO2. The interval between each concentric circle in the figure represents 50MPa. It can be seen from the figure that the stress values ​​of the 4-layer strain monitoring points at both ends of the jet direction are the largest, and the stress values ​​perpendicular to the jet direction are the smallest. Among them, the stress value of the third layer is the largest in the jet direction, about 225Mpa and 180Mpa at both ends. This is because the release head of the fracturing pipe 2 is facing the third layer. The farther the other monitoring points are from the injection point, the smaller the stress values.

[0090] Step S6 further comprises:

[0091] S61, calculating the force exerted by the shock wave of the fractured pipe 2 on the sleeve 4, establishing a polar coordinate system, and drawing a stress distribution diagram of the sleeve 4 wall in the polar coordinate system according to the calculation results;

[0092] S63, replacing sleeves 4 with different diameters to perform burst tests under different coupling conditions, and recording strain data collected by the strain gauge 5;

[0093] S64. Based on the strain data collected by the strain gauge 5, the stress distribution diagrams of the sleeve 4 wall under different coupling conditions are respectively drawn on the polar coordinate system in S61, and the energy concentration degrees under different coupling conditions are analyzed and compared by comparing the above-drawn stress distribution diagrams.

[0094] Step S61 further includes:

[0095] S611. Calculate the theoretical pressure value of the blasting on the 4 walls of the sleeve under the coupled blasting condition (the blasting condition where the fracturing tube 2 is in contact with the 4 walls of the sleeve):

[0096]

[0097] Among them, P b is the theoretical bursting pressure of the fractured pipe; C p and D are the shock wave velocity and detonation velocity in the sleeve respectively; ρ and ρ0 are the density of the sleeve and carbon dioxide respectively; P2 is the theoretical pressure value of the explosion on the sleeve wall under coupling conditions;

[0098] The theoretical bursting pressure P of the fracturing tube 2 can be calculated by using the thin-walled cylinder theory and combining the geometric conditions of the fracturing tube 2. b , is regarded as a known value, but this is not the innovation of this solution, so the calculation process is omitted.

[0099] S612. According to the relationship between the change in the peak pressure of the shock wave and the attenuation of the distance, the theoretical pressure value of the explosion on the wall of the sleeve 4 under the uncoupled condition (the explosion condition when the inner diameter of the sleeve 4 is larger than the diameter of the fracturing tube 2) is calculated:

[0100]

[0101] Among them, α is the attenuation exponent, which can be taken as α = 0.72; is the proportional distance; P w is the theoretical pressure value of the blasting on the sleeve wall under uncoupled conditions;

[0102] Specifically, The calculation process is:

[0103]

[0104] Among them, r b is the inner diameter of the sleeve, Q is the TNT equivalent of CO2, Q TNT is the explosion energy of 1kgTNT, take 4250kJ / kg; E g is the supercritical CO2 phase change pulse energy.

[0105] The calculation formula of explosion energy when the medium is compressed gas and water vapor:

[0106]

[0107] Where V is the volume of the fracturing tube. The test can use a 85-type fracturing tube with a volume of 0.0008516m 3 ; k is the adiabatic index of the gas, which can be taken as 1.3.

[0108] S613. Calculate the theoretical pressure value on the four walls of the sleeve:

[0109]

[0110] Among them, a r P is the radial clamping force of the clamp on the sleeve; e is the theoretical pressure value on the sleeve wall.

[0111] Will Substitute P e From the expression of e is a linear function related only to the inner diameter of the sleeve 4. When the inner diameter of the sleeve 4 is the same, the stress on the circumference of the sleeve 4 wall is theoretically equal everywhere, but it obviously cannot reflect the energy accumulation of the monitoring points at different angles. That is, in actual working conditions, the supercritical CO2 phase change fracturing pressure will change with the aperture of the fracturing hole 2.

[0112] S614, based on the distribution point position of the strain gauge 5 in the i-th layer strain assembly and the calculated P e The stress distribution curves under different sleeve 4 diameters are drawn on the polar coordinate system.

[0113] In one embodiment, sleeves 4 with outer diameters of 112 mm, 132 mm, and 140 mm are selected to start the test.

[0114] The strain component of the layer corresponding to the jet position is selected as the research object, and the peak strain and peak stress of the monitoring points of this layer are counted, and the following can be drawn: Fig.11 The stress distribution curve diagram shown is used to intuitively observe the stress concentration conditions under different coupling conditions (i.e., different diameters of the sleeve 4).

[0115] Fig.11 Only the theoretical curves of the sleeve 4 with outer diameters of 112 mm and 132 mm are shown, namely the red dotted line and the brown dotted line in the figure, which are two concentric circles.

[0116] It can be seen that the stress values ​​calculated theoretically are distributed in the form of concentric circles. Although the stress peak decreases with increasing radius, there is no obvious energy-gathering effect. On the contrary, the energy-gathering effect of the test value on the sleeve 4 of different radii is very obvious, among which the stress peak appears in the jet direction of the fracturing tube 2, and the minimum stress value is perpendicular to the jet direction. As the diameter of the sleeve 4 increases, the stress value of the sleeve 4 decays accordingly. In addition, the energy-gathering effect of the sleeve 4 gradually decreases, and even no longer appears when the diameter is 140 mm, indicating that the coupling state of the fracturing tube 2 and the borehole also has a great influence on the energy-gathering effect.

[0117] Preferably, the industrial camera 6 is arranged on one side of the test box 1, and the side of the test box 1 close to the industrial camera 6 is a transparent plate 15. The industrial camera 6 can collect images of the situation in the test box 1 in real time and upload them to the computer, so that the test personnel can observe the test situation. After the blasting, three-dimensional scanning can be used to measure the deformation amount, damage area and other parameters of the sleeve 4, which can more accurately evaluate the influence of the energy gathering effect on the stress field, and provide strong support for the subsequent blasting design and optimization.

[0118] In addition, in actual blasting projects, the fracturing tube 2 will be buried several meters or even hundreds of meters underground depending on the actual working conditions. The rock mass is subjected to various ground stresses underground. Different drilling depths will directly affect the stress field of the rock mass hole wall after blasting, which will greatly vary the blasting effect. Therefore, in order to make this test closer to the actual working conditions, a clamp 7 is also provided on the sleeve 4. When the clamp 7 clamps the sleeve 4, on the one hand, it can prevent the sleeve 4 from moving under force, and on the other hand, it can provide radial pressure for the sleeve 4 to simulate radial ground stress.

[0119] like Figure 2 As shown, the clamp 7 includes two clamping cylinders 71 arranged opposite to each other, and a clamping hole 72 penetrating the clamping cylinder 71 is provided at the edge of the clamping cylinder 71. When the two clamping cylinders 71 are pressed against each other, the two clamping holes 72 can be enclosed to form a columnar structure; a push rod 73 is fixedly connected to the side of the clamping cylinder 71 away from the clamping hole 72, and the push rod 73 is connected to the driver A, and the driver A is electrically connected to the control module.

[0120] The control module includes an electrically connected single chip microcomputer and a computer, and the data collected by the strain gauge 5 is transmitted to the computer for subsequent processing. The driver A is electrically connected to the single chip microcomputer and can output instructions for opening and closing the drive module of the clamp 7 through the computer terminal.

[0121] The clamping hole 72 is provided to fit the curved surface of the sleeve 4 . During the test, the clamping hole 72 can be in close contact with the sleeve 4 . The control module drives the push rod 73 to move by starting the driver, thereby controlling the distance between the two clamping cylinders 71 .

[0122] like Figure 3-4 As shown, the two opposite sides of the clamping cylinder 71 are open ends, and the two sides of the open ends are covered with elastic diaphragms 75, and the elastic diaphragm 75 is sealed and connected to the clamping cylinder 71; the interior of the clamping cylinder 71 is provided with a piston 74 that divides the internal cavity into two independent chambers, and the chamber close to the elastic diaphragm 75 is a working chamber 77 filled with liquid, and a push rod 76 fixedly connected to the piston 74 extends out of the other chamber of the clamping cylinder 71 and is connected to the driver B, and the driver B is electrically connected to the control module.

[0123] Driver A and driver B can be any driving mechanism capable of driving an object to perform linear motion, such as hydraulic driving or electric push rod driving. The connection node where the push rod 76 passes through the clamping cylinder 71 and the piston 74 and the inner wall of the clamping cylinder 71 are sealed.

[0124] First, the clamping cylinder 71 is pushed by the push rod 73 to move so that the elastic diaphragm 75 can contact the curved surface of the sleeve 4, and then the driver B is controlled to start to move the push rod 76, thereby pushing the piston 74, so that the volume of the working chamber 77 is reduced, and the liquid in the chamber is squeezed and moves toward the elastic diaphragm 75, squeezing the elastic diaphragm 75. The size of the clamping force on the sleeve 4 can be controlled by controlling the displacement of the push rod 76.

[0125] The elastic diaphragm 75 under pressure will produce elastic deformation and tightly wrap the sleeve 4, which can not only clamp the sleeve 4 to prevent the sleeve 4 from being displaced by the shock wave, but also simulate the confining pressure effect in the ground stress, so that the sleeve 4 is subjected to uniform or non-uniform radial pressure, making the test closer to the working conditions during the actual blasting. Compared with the hard contact clamping, this flexible contact clamping method does not affect the deformation of the sleeve 4 during blasting.

[0126] refer to Figure 8 The clamping hole 72 is a cylindrical structure with a semi-elliptical cross section, and the push rod 73 and the push rod 76 both extend out of the test box 1. The cross section of the clamping hole 72 is set to be semi-elliptical instead of circular because it can improve the adaptability and facilitate clamping of sleeves 4 with different diameters, so as to study the influence factors of sleeves 4 with different diameters on the energy-gathering effect.

[0127] After the clamping cylinder 71 clamps the sleeve 4, the elastic diaphragm 75 at the middle position can still tightly wrap the sleeve 4. The elastic diaphragms 75 at the top and bottom positions, due to the shape of the clamping cylinder 71, can be approximately regarded as point contact with the sleeve 4. The contact point a between the sleeve 4 and the top of the elastic diaphragm 75 is as shown in FIG. Figure 8 shown.

[0128] Preferably, a pressure gauge is provided on the clamping cylinder 71. When , the control module controls driver B to close.

[0129] Among them, a r is the preset radial clamping force of the clamp on the sleeve; π is the pi ratio; r is the outer radius of the sleeve; L is the length of the elastic diaphragm wrapped around the sleeve; P is the reading of the pressure gauge.

[0130] refer to Figure 5 Several strain components are evenly arranged along the length direction of the sleeve 4. One strain component includes several strain gauges 5 evenly distributed along the circumferential direction of the sleeve 4. The strain gauges 5 are all pasted to the inner wall of the sleeve 4, and the position where the strain gauges 5 are pasted does not exceed the range of the elastic diaphragm 75 wrapping the sleeve 4.

[0131] The strain gauge 5 is attached to the inner wall of the sleeve 4 to prevent the clamp 7 from touching the strain gauge 5 during clamping, causing damage or falling off of the strain gauge 5, which would result in data acquisition failure. The installation position of the strain gauge 5 can ensure that the strain acquisition point coincides with the ground stress simulation point. Since the strain gauge 5 on the inner wall will be directly affected by the blasting shock wave, the blasting force in the test can be appropriately reduced to avoid excessive blasting force affecting data acquisition and remove instantaneous large fluctuation data.

[0132] More specifically, refer to Figure 4 and Figure 6 A fixing column 8 with a threaded outer wall is fixedly connected to the bottom plate of the test box 1. The fixing column 8 passes through the bottom plate of the sleeve 4 and extends into the sleeve 4. A threaded hole matching the fixing column 8 is provided at the bottom of the fracturing tube 2. During the test, the fixing column 8 is threadedly connected to the fracturing tube 2.

[0133] The fixing column 8 can be welded at the center of the bottom plate of the test box 1. Connecting the fracturing tube 2 to the fixing column 8 can limit the displacement of the fracturing tube 2. Firstly, the impact force of the fracturing tube 2 can be prevented from causing the fracturing tube 2 to escape from the test box 1 and fly away, thereby affecting the test results or causing safety accidents. Secondly, the installation position of the fracturing tube 2 can be adjusted so that the jet port of the fracturing tube 2 is located in the area where the elastic diaphragm 75 wraps the sleeve 4.

[0134] refer to Figure 7The test box 1 includes a rectangular parallelepiped frame structure formed by angle steel 14, a bottom plate and a side plate fixed on the angle steel 14, and a top plate 11 is detachably connected to the angle steel 14 through a fixing member 13. The top plate 11 of the test box 1 is provided with a through hole 12 for the fracturing tube 2 to extend into; the test device also includes a limit support 3, which is fixed to the outer wall of the fracturing tube 2 and contacts the lower surface of the top plate 11 when in use; the surface area of ​​the limit support 3 is larger than the cross-sectional area of ​​the through hole 12 to further prevent the fracturing tube 2 from moving upward.

[0135] The assembly steps of the test box 1 are roughly as follows: first, the angle steel 14 is fixed into a rectangular frame by welding or other fixing connection methods, and then the bottom plate and four side panels of the rectangular parallelepiped are fixed respectively. Before fixing the top plate 11, the fixed fracturing tube 2 is first placed in the sleeve 4 and fixedly connected with the fixing column 8, and the installation position of the limit support 3 is measured so that the limit support 3 can just abut against the top plate 11, and then the limit support is fixed to the outside of the fracturing tube 2 by welding or other fixing methods.

[0136] Then the top plate 11 is fixedly connected to the angle steel 14 through the fixing piece 13. The top of the fracturing tube 2 is extended out of the top plate 11 from the through hole 12. After the test is completed, the top plate 11 can be disassembled by disassembling the fixing piece 13, and the fracturing tube 2 can be taken out. Among them, the transparent plate 15 is preferably a tempered glass plate, and the other side plates are preferably steel plates.

[0137] In addition, the sleeve 4 will not break into pieces like the rock mass in traditional tests, and the blasting process of this test is carried out in the test box 1, and the deformation process of the sleeve 4 is recorded by the industrial camera 6, so that the test personnel can remotely observe the test progress. Therefore, the test scheme in the present invention can significantly improve the test safety compared with the traditional test scheme.

[0138] In summary, the present invention can prolong the observation time and can intuitively observe the energy concentration state of the monitoring point at different angles and the energy concentration degree under different coupling conditions. In addition, the clamping force of the clamp 7 can be adjusted according to actual needs to simulate the initial ground stress on the wall of the sleeve 4 at different depths, so that the collected test data is closer to the actual working conditions.

Claims

1. A supercritical CO2 phase change energy testing method, characterized in that: The following steps are involved: S1. Assembling a test device, the test device comprising a sleeve (4) and a clamp (7), and an industrial camera (6) is placed on one side of the sleeve (4); S2, affixing a plurality of strain components to the wall of the sleeve (4), inserting the fracturing tube (2) into the sleeve (4), and fixing the fracturing tube (2); S3, controlling the clamp (7) to clamp the sleeve (4) through the control module, and recording the clamping force of the clamp (7); S4, detonating the fracturing tube (2), and using a strain component to collect and record strain data of the sleeve (4) in real time, and using an industrial camera (6) to collect and record the deformation process of the sleeve (4); S5. Calculate the peak stress of the same sleeve (4) at different locations based on the data collected by the strain component, and draw a stress distribution diagram of the sleeve (4); S6, replacing a sleeve (4) with a different diameter, repeating steps S2-S5, and performing several groups of tests, and drawing a stress distribution diagram reflecting the degree of energy concentration under different coupling conditions according to the stress distribution obtained in each group of tests; In step S5, further comprising: S51, the strain data recorded by the strain gauge (5) is , calculate the stress values ​​of various parts of the sleeve (4) respectively: in, For the Layer strain components; is the first strain gauges; I is the total number of layers of the strain component, N is the total number of strain gauges in the strain assembly; For the Layer strain component Strain data collected by strain gauges; The first Layer strain component The stress value at the corresponding position of each strain gauge; S52, establishing a polar coordinate system with the center of the sleeve cross section as the origin, in which the polar diameter is the magnitude of the stress value, and the polar angle is the angle passed by the line from the reference axis to the origin and a certain point in a counterclockwise rotation; S53, drawing a stress distribution curve diagram on a polar coordinate system based on the distribution points of the strain gauges in the first layer strain assembly and the calculated stress values; S54, according to the method of step S53, draw the second to the third polar coordinates in the same polar coordinate system. I Stress distribution curve of the layer; In step S6, the steps further include: S61, calculating the force exerted on the sleeve (4) by the shock wave of the fractured pipe (2), establishing a polar coordinate system, and drawing a stress distribution diagram of the sleeve (4) wall in the polar coordinate system according to the calculation results; S62, replacing sleeves (4) with different diameters to perform burst tests under different coupling conditions, and recording strain data collected by the strain gauge (5); S63, based on the strain data collected by the strain gauge (5), respectively draw stress distribution diagrams of the sleeve (4) wall under different coupling conditions on the polar coordinate system in step S61; Step S61 further includes: S611. Calculate the theoretical pressure value of the explosion on the wall of the sleeve (4) under the coupled explosion condition: in, is the theoretical bursting pressure of the fractured pipe; and are the shock wave velocity and detonation velocity in the sleeve respectively; and are the densities of the sleeve and carbon dioxide, respectively; is the theoretical pressure value of explosion on the sleeve wall under coupling conditions; S612. Calculate the theoretical pressure value of the explosion on the wall of the sleeve (4) under uncoupled conditions: in, is the decay index; is the proportional distance; is the theoretical pressure value of the blasting on the sleeve wall under uncoupled conditions; S613. Calculate the theoretical pressure value on the wall of the sleeve (4): in, is the radial clamping force of the clamp on the sleeve; is the theoretical pressure value on the sleeve wall; S614, The distribution points of the strain gauges (5) in the layer strain assembly and the calculated Based on the value, a stress distribution curve diagram under different sleeve (4) diameters is drawn on the polar coordinate system.

2. The supercritical CO2 phase change energy testing method according to claim 1 is characterized in that: The strain components are evenly arranged along the length direction of the sleeve (4), and one strain component comprises a plurality of strain gauges (5) evenly distributed in the circumferential direction along the wall of the sleeve (4).

3. The supercritical CO2 phase change energy testing method according to claim 1 is characterized in that: The test device also includes a test box (1), wherein the sleeve (4) and the clamp (7) are both arranged inside the test box (1); The test box (1) comprises a rectangular parallelepiped frame structure formed by angle steel (14), and a bottom plate and side panels fixed to the angle steel (14); the top plate (11) is detachably connected to the angle steel (14) via a fixing member (13); An industrial camera (6) electrically connected to the control module is provided on one side of the test box (1), and a transparent plate (15) is provided on the side of the test box (1) close to the industrial camera (6); A fixing column (8) provided with an external thread is fixedly connected to the bottom plate of the test box (1); the fixing column (8) passes through the bottom plate of the sleeve (4) and extends into the interior of the sleeve (4); a threaded hole matching the fixing column (8) is provided at the bottom of the fracturing tube (2); during the test, the fixing column (8) is threadedly connected to the fracturing tube (2).

4. The supercritical CO2 phase change energy testing method according to claim 3 is characterized in that: The clamp (7) comprises two clamping cylinders (71) arranged opposite to each other, the edges of the clamping cylinders (71) are provided with clamping holes (72) penetrating the clamping cylinders (71), and the cross-section of the clamping holes (72) is semi-elliptical; a push rod (73) is fixedly connected to the side of the clamping cylinders (71) away from the clamping holes (72), and the push rod (73) is connected to a driver A, and the driver A is electrically connected to a control module.

5. The supercritical CO2 phase change energy testing method according to claim 4 is characterized in that: Two opposite sides of the clamping cylinder (71) are open ends, and two sides of the open ends are covered with elastic diaphragms (75), and the elastic diaphragms (75) are sealed and connected to the clamping cylinder (71); A piston (74) is arranged inside the clamping cylinder (71) to divide the internal cavity into two independent chambers. The chamber close to the elastic diaphragm (75) is a working chamber (77) filled with liquid. A push rod (76) fixedly connected to the piston (74) extends out of the other chamber of the clamping cylinder (71) and is connected to a driver B. The driver B is electrically connected to a control module. The strain gauges (5) are all adhered to the inner wall of the sleeve (4), and the position where the strain gauges (5) are adhered does not exceed the range where the elastic diaphragm (75) wraps around the sleeve (4).

6. The supercritical CO2 phase change energy testing method according to claim 4 is characterized in that: A pressure gauge is provided on the clamping cylinder (71). When the pressure gauge displays When , the control module controls the driver B to close; in, is the ratio of pi; is the outer radius of the sleeve; The length of the sleeve wrapped by the elastic diaphragm; is the pressure gauge reading.

7. The supercritical CO2 phase change energy testing method according to claim 3 is characterized in that: The top plate (11) of the test box (1) is provided with a through hole (12) for the fracturing tube (2) to extend into; the test device also includes a limit support (3) which, when in use, is fixed to the outer wall of the fracturing tube (2) and contacts the lower surface of the top plate (11); the surface area of ​​the limit support (3) is greater than the cross-sectional area of ​​the through hole (12).

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