Test device and method for simulating high-velocity penetration impact effect

Abstract

The application discloses a test device and method for simulating the impact effect of super-high-speed penetration into the ground, wherein a static load loading system is used to apply static load to the periphery of a sample to simulate the ground stress environment, and a dynamic load loading system is used to apply impact dynamic load to the top of the sample to simulate the ground impact, wherein in the dynamic load loading system, a phase change reaction kettle is used to heat liquid CO2 to a supercritical high-pressure state, a liquid charging module is used to charge the phase change reaction kettle with liquid CO2, a barrel is used to receive the high-pressure gas released by the phase change reaction kettle and form an approximately planar ground shock wave, a stress wave lens module is used to adjust the width of the ground shock wave through a stress wave lens combination and act on the sample, and a control module can control the peak pressure of the ground shock wave by regulating the heating power of the phase change reaction kettle and can control the duration of the ground shock wave by adjusting the aperture of the barrel. The application realizes controllable and high-fidelity simulation of the impact effect of super-high-speed penetration into the ground.

Description

Technical Field

[0001] This invention belongs to the field of deep earth protection engineering, specifically relating to a test device and method for simulating the impact effect of ultra-high-speed ground penetration. Background Technology

[0002] In the field of deep-earth defense engineering, with the development of kinetic energy weapons and the increasing requirements for space protection, the dynamic response, terminal effect, and secondary effects between objects under hypersonic action, as well as related offensive and defensive technologies, have become research hotspots. Unlike the instantaneous energy release of an explosion, the ground shock effect generated by a hypersonic missile after penetrating a protective structure is characterized by high peak value and long duration. The resulting ground shock wave can cause severe damage to deep rock masses, building structures, and protective engineering. In addition, deep rock masses are in a complex high-stress environment for a long time, and strong disturbances such as ground shocks can easily induce the failure of important protective engineering such as underground fortifications and ammunition depots, seriously threatening safety. Therefore, systematically revealing the interaction mechanism between ground shock and the stress environment, and gaining a deeper understanding of the response and failure mechanism of building structures and surrounding rock masses under their coupled action, has important scientific significance and engineering value for effectively controlling ground shock damage and optimizing the design of protective engineering.

[0003] As an indispensable tool for conducting research on such issues, physical model tests play a crucial role in revealing the mechanical response, failure evolution process, and disaster-causing mechanism of deep rock masses under the coupled action of strong dynamic and high static loads. However, due to limitations in experimental scale, loading methods, and experimental conditions, existing physical model tests have limited experience in realistically reproducing protective engineering and ground impact effects, and lack the equipment to conduct such experiments.

[0004] Currently, the simulation technology for ultra-high-speed ground-penetrating impact effects has the following limitations:

[0005] 1) Unable to generate shock wave curves that meet the requirements: At present, most shock waves are generated by direct detonation of explosives or activators, resulting in short-duration shock wave curves that cannot meet the long-duration characteristics of ultra-high-speed penetration shock effects.

[0006] 2) Limited dynamic load application: Most simulation devices use "gas-driven piston impact" to generate pressure pulses. Although this method has good safety and controllability, the generated pulse waveforms (such as triangular waves or rectangular waves) and spatial shapes (mostly broad plane waves) are relatively limited, making it difficult to realistically simulate the complex dynamic process of shock wave propagation and evolution in three-dimensional space.

[0007] 3) Insufficient wavefront shaping technology: There is currently a lack of efficient and controllable wavefront shaping methods. How to convert the planar ground shock waves that are easily generated under laboratory conditions into large-scale spherical or cylindrical converging waves with high efficiency and low energy loss to form a penetration effect remains a key scientific and technological challenge to improve the realism of physical simulation of ground shock disturbances.

[0008] Therefore, it is currently impossible to achieve a controllable and high-fidelity simulation of the impact effect of ultra-high-speed ground penetration. Summary of the Invention

[0009] The purpose of this invention is to provide a test apparatus for simulating the ultra-high-speed ground-penetrating impact effect, and a test method for simulating the ultra-high-speed ground-penetrating impact effect. This application achieves controllable and high-fidelity simulation of the ultra-high-speed ground-penetrating impact effect.

[0010] The technical solution adopted in this invention is:

[0011] An experimental apparatus for simulating the effects of ultra-high-speed ground-penetrating impacts includes:

[0012] The test chamber is used to place the test sample;

[0013] A static load system is used to apply a static load around the specimen to simulate a geostress environment.

[0014] A dynamic load system for applying a dynamic impact load to the top of a specimen to simulate ground impact includes:

[0015] A phase change reactor, equipped with a heating mechanism, a liquid inlet valve, and a gas outlet valve, is used to heat liquid CO2 to a supercritical high-pressure state.

[0016] The liquid filling module, connected to the liquid inlet valve, is used to fill the phase change reactor with liquid CO2;

[0017] The barrel, connected to the exhaust valve, has a variable orifice and is used to receive the high-pressure gas released from the phase change reactor and form an approximately planar ground shock wave.

[0018] The stress wave lens module is tightly installed between the end of the barrel and the top surface of the specimen. It is used to adjust the width of the shock wave through the stress wave lens combination and apply it to the specimen.

[0019] The control module can control the opening and closing of the liquid inlet valve and the gas outlet valve, control the peak pressure of the shock wave by adjusting the heating power of the phase change reactor, and control the duration of the shock wave by adjusting the barrel diameter.

[0020] Preferably, the stress wave lens module is cylindrical, and its interior is provided with a convex stress wave lens that can focus the incident ground shock wave and a concave stress wave lens that can diverge the incident ground shock wave. The convex and concave stress wave lenses are separated from each other, and the area outside the convex and concave stress wave lenses is filled with a propagation medium. The combination of the convex and concave stress wave lenses can focus or diverge the ground shock wave, thereby adjusting the width of the ground shock wave.

[0021] Preferably, the stress wave lens module is detachably mounted on the top surface of the sample, and the barrel is mounted on the test chamber with its end tightly attached to the top surface of the stress wave lens module.

[0022] Preferably, the phase change reactor also has a monitoring and protection mechanism, which includes a safety valve for depressurization to prevent overpressure and sensors for monitoring the temperature and pressure inside the phase change reactor.

[0023] Preferably, the inner bore of the gun barrel is formed by multiple radially contracting plates along the line, and the contraction of the multiple radially contracting plates is controlled by hydraulic pipes.

[0024] Preferably, the liquid filling module, phase change reactor, and gun barrel are connected sequentially from top to bottom and installed on the top of the test chamber.

[0025] Preferably, the liquid filling module includes a CO2 storage chamber, a high-pressure pump, and a high-pressure liquid CO2 storage tank connected in sequence.

[0026] Preferably, the static load loading system includes hydraulic loading cylinders corresponding to the four sides of the specimen. The hydraulic loading cylinders are installed on the side of the test chamber and the test chamber provides the reaction force. The loading end of the hydraulic loading cylinder is provided with a pressure head, and the side of the specimen is provided with a pressure plate. The pressure head can extend into the test chamber and act on the corresponding pressure plate. All hydraulic loading cylinders can apply static load to the four sides of the specimen in a pairwise clamping manner.

[0027] Preferably, the test chamber is equipped with an internal guide rail, and the test chamber is equipped with a longitudinal guide rail in the front-to-back direction. The longitudinal guide rail is connected to the internal guide rail. The hydraulic loading cylinder on the side of the longitudinal guide rail is detachably installed on the test chamber through a reaction frame. After the reaction frame is disconnected from the test chamber, it can move back and forth along the longitudinal guide rail. A loading platform is provided on one side of the longitudinal guide rail, and the sample can be transferred between the loading platform and the longitudinal guide rail, as well as between the longitudinal guide rail and the internal guide rail.

[0028] A test method for simulating the effect of ultra-high-speed ground impact involves applying a static load around the specimen to simulate the ground stress environment and applying a dynamic impact load to the top of the specimen to simulate ground impact. The method for applying the dynamic impact load is as follows: first, liquid CO2 is quantitatively charged into a phase change reactor, then the liquid CO2 is heated to a supercritical high-pressure state, and the peak pressure of the ground impact wave is controlled by adjusting the heating power. When the phase change reactor reaches the preset peak pressure, the gas outlet valve of the phase change reactor is opened, allowing the high-pressure gas released from the phase change reactor to enter the barrel and form an approximately planar ground impact wave. After the ground impact wave width is adjusted by a stress wave lens combination, it acts on the specimen. The duration of the ground impact wave is controlled by pre-adjusting the barrel aperture.

[0029] Preferably, the method for controlling the peak pressure of the shock wave by adjusting the heating power is as follows:

[0030] While heating the phase change reactor to induce a phase change of liquid CO2, the temperature and pressure changes inside the phase change reactor are monitored in real time.

[0031] Helmholtz free energy of supercritical CO2 based on the Span-Wagner equation The calculation formula is

[0032] (1)

[0033] in, To reduce density, there are , This represents the actual density of CO2 inside the phase change reactor. This is the critical density of CO2; The ratio of the critical temperature to the actual temperature is given by: , This is the critical temperature for CO2. This represents the actual temperature of CO2 inside the phase change reactor. It is the gas constant; Let Helmholtz free energy be the dimensionless energy of a gas assuming it is perfectly ideal and free from intermolecular interactions. The dimensionless Helmholtz free energy is the residual portion produced during the CO2 phase transition process. For the Helmholtz free energy of an ideal gas, This refers to the residual Helmholtz free energy generated during the phase transition process;

[0034] According to formula (1), in the supercritical CO2 phase transition process, the pressure-related quantities The relationship between temperature and the equation is:

[0035] (2)

[0036] in, The residual dimensionless Helmholtz free energy pair The partial derivatives are expressed by the following formula.

[0037] (3)

[0038] in, ; The macroscopic volumetric properties of supercritical CO2 at low density or far from the critical state are characterized by the basic polynomial. Characterizing the fluid properties of supercritical CO2 in a high-density state, with high-density index correction; The Gaussian correction term characterizes the drastic property changes exhibited by supercritical CO2 near the critical point. Characterizes the nonanalytic singular behavior of supercritical CO2 near the critical point; , , , , , , , , , , , , , These are constants obtained experimentally under the supercritical state of CO2;

[0039] Considering the constant volume and gas mass within the phase change reactor, the relationship between the pressure increase rate and temperature is:

[0040] (4)

[0041] Combining formulas (2) to (4), the heating power is adjusted by PID control to change the temperature inside the phase change reactor, thereby achieving precise control of the CO2 pressure inside the phase change reactor.

[0042] Preferably, the weight of liquid CO2 charged into the phase change reactor is calculated. The method is:

[0043] Based on the peak shock wave pressure determined by the experimental design, and using the similarity criterion, the CO2 filling volume was established. Mapping relationship with peak pressure of ground shock wave

[0044] (5)

[0045] in, The energy conversion efficiency coefficient. To calculate the load scaling ratio based on the similarity criterion, This represents the actual density of CO2 inside the phase change reactor. This refers to the volume of the phase change reactor.

[0046] Preferably, the method for determining the bore diameter of the gun barrel is as follows:

[0047] The process of releasing high-pressure gas from the phase change reactor is considered an isentropic expansion process. The gas pressure inside the reactor gradually decreases over time. Based on the theory of compressible gas flow, the mass flow rate inside the phase change reactor is expressed as:

[0048] (6)

[0049] in, The mass flow rate of the gas released through the exhaust valve and the gun barrel. For flow coefficient, This is the effective cross-sectional area of ​​the gun barrel. For the local speed of sound, This is the specific heat ratio of CO2;

[0050] When the pressure inside the phase change reactor meets the critical flow condition, the high-pressure supercritical gas forms a confined jet flow within the outlet valve. The relationship between the gas release rate and the pressure evolution process can be obtained from mass conservation.

[0051] (7)

[0052] in, This represents the actual volume of supercritical CO2.

[0053] Combining formulas (6) and (7) with the isentropic relationship, the pressures on the phase change reactor and the gun barrel are obtained. The decay equation over time is:

[0054] (8)

[0055] in, The constants related to the volume of the phase change reactor, gas properties, and temperature are expressed as follows:

[0056] (9)

[0057] Under the condition that the volume of the phase change reactor is constant, the duration of the ground shock wave is positively correlated with the release rate of the high-pressure gas in the phase change reactor and negatively correlated with the effective cross-sectional area of ​​the gun barrel. Combining formulas (8) and (9) and the required duration of the ground shock wave, the diameter of the gun barrel is determined.

[0058] Preferably, the method for determining the relevant parameters of the stress wave lens is as follows:

[0059] A combination of a convex stress wave lens and a concave stress wave lens is used, with a propagation medium filling the space between and around the convex and concave stress wave lenses. Let the focal length of the convex stress wave lens be... The focal length of the stress wave concave lens is The convex stress wave lens and the concave stress wave lens are coaxial and spaced apart. For a collimated wave to remain collimated after passing through a convex stress wave lens and a concave stress wave lens, the following condition must be met:

[0060] (10)

[0061] Let the beamwidth of the input shock wave be... The output shock beam width is The wavefront curvature control factor of the stress wave lens in the straight wave range. Represented as

[0062] or (11)

[0063] Let the material density and impedance of the propagation medium be respectively... , The material density, curvature, and impedance of the stress wave convex lens are respectively... , , The material density, curvature, and impedance of the stress wave concave lens are respectively... , , The relationship between the focal lengths of the two lenses is expressed as follows:

[0064] (12)

[0065] (13)

[0066] The beam width of the input shock wave is determined by the bore diameter of the gun barrel. The output shock beam width is determined according to the experimental requirements. ,Compare and ,when > Then, the convex lens and concave lens of the stress wave are arranged vertically. < Then, the concave stress wave lens and the convex stress wave lens are arranged vertically, first according to the wavefront curvature control factor. Sure , And then according to and Determine the specific parameters of the propagation medium, the convex lens of the stress wave, and the concave lens of the stress wave.

[0067] The beneficial effects of this invention are:

[0068] This application overcomes the limitations of existing technologies that use explosives or traditional mechanical impact methods to precisely control parameters such as the peak value, duration, and wavefront shape of the shock wave, achieving controllable and high-fidelity simulation of ultra-high-speed penetrating ground impact effects. This application applies static and dynamic impact loads to the sample, realistically simulating the coupling effect of high ground stress and strong impact in deep rock masses. This application achieves controlled phase change and restricted release of liquid CO2, controlling the peak pressure of the shock wave by adjusting the heating power of the phase change reactor, and controlling the duration of the shock wave by adjusting the borehole diameter, thus obtaining shock waves with different peak loads and long durations. This application adjusts the width of the shock wave using a combination of stress wave lenses, converting planar shock waves into different ranges of impact loads, thereby expanding the controllable range of impact loading spatial morphology. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is an overall diagram of the experimental apparatus used in this application to simulate the effects of ultra-high-speed ground penetration.

[0071] Figure 2 This is a cross-sectional view of the experimental apparatus used in this application to simulate the effects of ultra-high-speed ground penetration.

[0072] Figure 3 This is a cross-sectional view of the stress wave lens module in this application.

[0073] Figure 4 This is a schematic diagram of the process of applying an impact dynamic load to the top of the specimen to simulate ground impact in this application.

[0074] Figure 5 This is a schematic diagram of the process for adjusting the width of the ground shock wave using a combination of stress wave lenses in this application.

[0075] Figure 6 This is a schematic diagram illustrating the principle of focusing shock waves using a combination of stress wave lenses in this application.

[0076] Figure 7 This is a schematic diagram illustrating the principle of the shock wave generated by the combination of stress wave lenses in this application.

[0077] Figure 8 This is a comparison of the Pt curves of the high-speed ground-penetrating shock wave generated by this application and the conventional explosive shock.

[0078] In the diagram: 1-Longitudinal guide rail; 2-Base; 3-Test chamber; 4-Hydraulic loading cylinder; 5-Dynamic loading system; 6-Reaction frame; 7-Platform; 8-Indenter; 9-Sample; 10-Stress wave lens module; 11-Hydraulic pipeline; 12-Outlet valve; 13-Phase change reactor; 14-Filling module; 15-Inlet valve; 16-Heating mechanism; 17-Multi-lobed radial shrinkage plate; 18-Barrel; 19-Pressure plate; 20-Internal guide rail; 21-Stress wave convex lens; 22-Propagation medium; 23-Stress wave concave lens. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0080] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0081] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0082] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0083] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0084] Example 1

[0085] This embodiment discloses an experimental apparatus for simulating the effects of ultra-high-speed ground-penetrating impacts, such as... Figure 1 and Figure 2 As shown, it includes a test chamber 3, a static load loading system, and a dynamic load loading system 5. Wherein: as... Figure 1 and Figure 2 As shown, test chamber 3 is used to place sample 9. Figure 1 and Figure 2 As shown, the static load system is used to apply a static load to the perimeter of specimen 9 to simulate a geostress environment. Figure 1 and Figure 2 As shown, the dynamic load system 5 is used to apply an impact dynamic load to the top of the sample 9 to simulate ground impact. The dynamic load system 5 includes a phase change reactor 13, a liquid filling module 14, a barrel 18, a stress wave lens module 10, and a control module. The phase change reactor 13 has a heating mechanism 16, a liquid inlet valve 15, and a gas outlet valve 12. The phase change reactor 13 is used to heat liquid CO2 to a supercritical high-pressure state. The liquid filling module 14 is connected to the liquid inlet valve 15 and is used to fill the phase change reactor 13 with liquid CO2. The barrel 18 is connected to the gas outlet valve 12. The aperture of the barrel 18 is variable. The barrel 18 is used to receive the high-pressure gas released from the phase change reactor 13 and form an approximately planar ground shock wave. The stress wave lens module 10 is tightly installed between the end of the barrel 18 and the top surface of the sample 9. The stress wave lens module 10 is used to adjust the width of the ground shock wave through the stress wave lens combination and act on the sample 9. The control module can control the opening and closing of the liquid inlet valve 15 and the gas outlet valve 12, can control the peak pressure of the ground shock wave by adjusting the heating power of the phase change reactor 13, and can control the duration of the ground shock wave by adjusting the aperture of the barrel 18.

[0086] Regarding static load systems:

[0087] like Figure 1 and Figure 2 As shown, the static load loading system includes hydraulic loading cylinders 4 corresponding to the four sides of the specimen 9. The hydraulic loading cylinders 4 are installed on the side of the test chamber 3 and the test chamber 3 provides the reaction force. The loading end of the hydraulic loading cylinder 4 is provided with a pressure head 8. The side of the specimen 9 is provided with a pressure plate 19. The pressure head 8 can extend into the test chamber 3 and act on the corresponding pressure plate 19. All hydraulic loading cylinders 4 can apply static load to the four sides of the specimen 9 in a pair-by-pair manner. The static load loading system adopts a multi-axis loading structure. During operation, it is only necessary to control the loading force of each axis.

[0088] And, as Figure 1 and Figure 2As shown, the test chamber 3 is equipped with an internal guide rail 20, and the test chamber 3 is equipped with a longitudinal guide rail 1 in the front-to-back direction. The longitudinal guide rail 1 is connected to the internal guide rail 20. The hydraulic loading cylinder 4 on the side of the longitudinal guide rail 1 is detachably mounted on the test chamber 3 via a reaction frame 6. After the reaction frame 6 is disconnected from the test chamber 3, it can move back and forth along the longitudinal guide rail 1. A platform 7 is provided on one side of the longitudinal guide rail 1, and the sample 9 can be transferred between the platform 7 and the longitudinal guide rail 1, and between the longitudinal guide rail 1 and the internal guide rail 20. This arrangement facilitates the entry and exit of the sample 9 from the test chamber 3. During the process of the sample 9 entering and exiting the test chamber 3, the hydraulic loading cylinder 4 and its reaction frame 6 on one side can be allowed to leave the test chamber 3 along the longitudinal guide rail 1 to avoid obstructing the entry and exit of the sample 9. After the sample 9 enters the test chamber 3 and is positioned, the hydraulic loading cylinder 4 and its reaction frame 6 on one side can then be allowed to move closer to the test chamber 3 along the longitudinal guide rail 1 and be mounted on the test chamber 3.

[0089] like Figure 1 and Figure 2 As shown, in this embodiment, the test chamber 3 is mounted on the base 2.

[0090] Regarding dynamic load loading system 5:

[0091] In this embodiment, preferably: Figure 1 and Figure 2 As shown, the liquid filling module 14, the phase change reactor 13, and the gun barrel 18 are connected sequentially from top to bottom and installed on the top of the test chamber 3.

[0092] In this embodiment, preferably, the liquid filling module 14 includes a CO2 storage chamber, a high-pressure pump, and a high-pressure liquid CO2 storage tank connected in sequence.

[0093] In this embodiment, the heating mechanism 16 includes a heating rod and a high-power power supply.

[0094] In this embodiment, preferably, both the liquid inlet valve 15 and the air outlet valve 12 are one-way valves to prevent backflow.

[0095] In this embodiment, preferably, the phase change reactor 13 also has a monitoring and protection mechanism, which includes a safety valve for depressurization to prevent overpressure and a sensor for monitoring the temperature and pressure inside the phase change reactor 13.

[0096] In this embodiment, preferably: Figure 2 As shown, the inner bore of the gun barrel 18 is formed by a multi-lobed radial contraction plate 17 along the line, and the contraction of the multi-lobed radial contraction plate 17 is controlled by a hydraulic pipe 11. By adopting a structure similar to that of an expansion wave artillery, the inner diameter of the gun barrel 18 can be continuously adjusted.

[0097] In this embodiment, preferably, the barrel 18 is equipped with a sensor for real-time monitoring of pressure changes inside the barrel 18.

[0098] In this embodiment, preferably: Figure 3 As shown, the stress wave lens module 10 is cylindrical, and its interior is provided with a stress wave convex lens 21 that can focus the incident ground shock wave and a stress wave concave lens 23 that can diverge the incident ground shock wave. The stress wave convex lens 21 and the stress wave concave lens 23 are separated from each other, and the area outside the stress wave convex lens 21 and the stress wave concave lens 23 is filled with a propagation medium 22. The combination of the stress wave convex lens 21 and the stress wave concave lens 23 can focus or diverge the ground shock wave, thereby adjusting the width of the ground shock wave.

[0099] Furthermore, the stress wave convex lens 21, stress wave concave lens 23, and propagation medium 22 are made of materials with similar wave impedance, which can reduce interface reflection loss, achieve precise control of the stress wave energy density distribution, and improve the transmittance of the stress wave. The stress wave convex lens 21, stress wave concave lens 23, and propagation medium 22 can be made of materials such as pure steel, aluminum alloy, and pure copper, depending on the experimental requirements; however, the three materials cannot be the same.

[0100] In this embodiment, preferably, the stress wave lens module 10 is detachably mounted on the top surface of the sample 9, and the barrel 18 is mounted on the test chamber 3 with its end tightly attached to the top surface of the stress wave lens module 10, making installation convenient.

[0101] Example 2

[0102] This embodiment discloses a test method for simulating the effect of ultra-high-speed ground penetration impact. A static load is applied to the perimeter of the specimen 9 to simulate the ground stress environment, and a dynamic impact load is applied to the top of the specimen 9 to simulate ground impact. The method for applying the dynamic impact load is as follows: Figure 4 As shown: First, liquid CO2 is quantitatively charged into the phase change reactor 13. Then, the liquid CO2 is heated to a supercritical high-pressure state, and the peak pressure of the shock wave is controlled by adjusting the heating power. When the phase change reactor 13 reaches the preset peak pressure, the gas outlet valve 12 of the phase change reactor 13 is opened, so that the high-pressure gas released by the phase change reactor 13 enters the barrel 18 and forms an approximately planar shock wave. After the shock wave width is adjusted by the stress wave lens combination, it acts on the sample 9. The duration of the shock wave is controlled by pre-adjusting the orifice diameter of the barrel 18.

[0103] In this embodiment, preferably, the method of controlling the peak pressure of the shock wave by adjusting the heating power is as follows:

[0104] While heating the phase change reactor 13 to induce a phase change of liquid CO2, the temperature and pressure changes inside the phase change reactor 13 are monitored in real time.

[0105] Helmholtz free energy of supercritical CO2 based on the Span-Wagner equation The calculation formula is

[0106] (1)

[0107] in, To reduce density, there are , This represents the actual density of CO2 inside phase change reactor 13. This is the critical density of CO2; The ratio of the critical temperature to the actual temperature is given by: , This is the critical temperature for CO2. This represents the actual temperature of CO2 inside phase change reactor 13. It is the gas constant; Let Helmholtz free energy be the dimensionless energy of a gas assuming it is perfectly ideal and free from intermolecular interactions. The dimensionless Helmholtz free energy is the residual portion produced during the CO2 phase transition process. For the Helmholtz free energy of an ideal gas, This refers to the residual Helmholtz free energy generated during the phase transition process;

[0108] According to formula (1), in the supercritical CO2 phase transition process, the pressure-related quantities The relationship between temperature and the equation is:

[0109] (2)

[0110] in, The residual dimensionless Helmholtz free energy pair The partial derivatives are expressed by the following formula.

[0111] (3)

[0112] in, ; The macroscopic volumetric properties of supercritical CO2 at low density or far from the critical state are characterized by the basic polynomial. Characterizing the fluid properties of supercritical CO2 in a high-density state, with high-density index correction; The Gaussian correction term characterizes the drastic property changes exhibited by supercritical CO2 near the critical point. Characterizes the nonanalytic singular behavior of supercritical CO2 near the critical point; , , , , , , , , , , , , , This is a constant obtained experimentally under the supercritical state of CO2; see Span, R., & Wagner, W. (1996). A new equation of state for carbon dioxide covering the fluid region from the triple-point temperature to 1100 K at pressures up to 800 MPa. Journal of Physical and Chemical Reference Data, 25(6), 1509–1596.

[0113] Considering that the volume of the phase change reactor 13 is constant and the gas mass is constant, the relationship between the pressure increase rate and temperature is:

[0114] (4)

[0115] Combining formulas (2) to (4), the heating power is adjusted by PID control to change the temperature inside the phase change reactor 13, thereby achieving precise control of the CO2 pressure inside the phase change reactor 13.

[0116] In this embodiment, preferably, the weight of liquid CO2 filled into the phase change reactor 13 is calculated. The method is:

[0117] Based on the peak shock wave pressure determined by the experimental design, and using the similarity criterion, the CO2 filling volume was established. Mapping relationship with peak pressure of ground shock wave

[0118] (5)

[0119] in, The energy conversion efficiency coefficient. To calculate the load scaling ratio based on the similarity criterion, This represents the actual density of CO2 inside phase change reactor 13. The volume of phase change reactor 13.

[0120] In this embodiment, preferably, the method for determining the bore diameter of the gun barrel is as follows:

[0121] The process of releasing high-pressure gas from the phase change reactor 13 is considered as an isentropic expansion process. The gas pressure inside the phase change reactor 13 gradually decreases over time. Based on the theory of compressible gas flow, the mass flow rate inside the phase change reactor 13 is expressed as:

[0122] (6)

[0123] in, The mass flow rate of the gas released through the exhaust valve 12 and the gun barrel 18. This is the flow coefficient (typically 0.6~0.8). This is the effective cross-sectional area of ​​the gun barrel 18. For the local speed of sound, This is the specific heat ratio of CO2;

[0124] When the pressure inside the phase change reactor 13 meets the critical flow condition, the high-pressure supercritical gas forms a confined jet flow within the outlet valve 12. The relationship between the gas release rate and the pressure evolution process can be obtained from the law of mass conservation.

[0125] (7)

[0126] in, This represents the actual volume of supercritical CO2.

[0127] Combining formulas (6) and (7) with the isentropic relationship, the pressures on the phase change reactor 13 and the barrel 18 are obtained. The decay equation over time is:

[0128] (8)

[0129] in, The constants related to the volume, gas properties, and temperature of phase change reactor 13 are expressed as follows:

[0130] (9)

[0131] Under the condition that the volume of the phase change reactor 13 is constant, the duration of the ground shock wave is positively correlated with the release rate of the high-pressure gas in the phase change reactor 13 and negatively correlated with the effective cross-sectional area of ​​the gun barrel 18. Combining formulas (8) and (9) and the required duration of the ground shock wave, the aperture of the gun barrel 18 is determined.

[0132] In this embodiment, preferably, the method for determining the relevant parameters of the stress wave lens is as follows: Figures 5 to 7 As shown:

[0133] A combination of a convex stress wave lens 21 and a concave stress wave lens 23 is used, with a propagation medium 22 filling the space between and on the outer side of the convex stress wave lens 21 and the concave stress wave lens 23. Let the focal length of the convex stress wave lens 21 be... The focal length of the 23-cell concave lens with stress wave is The convex stress wave lens 21 and the concave stress wave lens 23 are coaxial and spaced apart. For a collimated wave to remain collimated after passing through the convex stress wave lens 21 and the concave stress wave lens 23, the following condition must be met:

[0134] (10)

[0135] Let the beamwidth of the input shock wave be... The output shock beam width is The wavefront curvature control factor of the stress wave lens in the straight wave range. Represented as

[0136] or (11)

[0137] Let the material density and impedance of the propagation medium 22 be respectively... , The material density, curvature, and impedance of the stress wave convex lens 21 are respectively... , , The material density, curvature, and impedance of the stress wave concave lens 23 are respectively... , , The relationship between the focal lengths of the two lenses is expressed as follows:

[0138] (12)

[0139] (13)

[0140] The beam width of the input shock wave is determined by the aperture of the gun barrel 18. The output shock beam width is determined according to the experimental requirements. ,Compare and ,when > Then, the stress wave convex lens 21 and the stress wave concave lens 23 are arranged vertically. < Then, the concave stress wave lens 23 and the convex stress wave lens 21 are arranged vertically, first according to the wavefront curvature control factor. Sure , And then according to and Determine the specific parameters of the propagation medium 22, the stress wave convex lens 21, and the stress wave concave lens 23.

[0141] like Figure 8As shown, this application overcomes the limitations of existing technologies that use explosives or traditional mechanical impact methods, which make it difficult to precisely control parameters such as the peak dynamic load, duration of action, and wavefront shape of the shock wave, achieving controllable and high-fidelity simulation of the ultra-high-speed ground-penetrating impact effect:

[0142] First, this application applies static load and impact dynamic load to sample 9, which can realistically simulate the coupling effect of high ground stress and strong impact in deep rock mass.

[0143] Second, this application controls the phase change of liquid CO2 and releases it in a limited manner. By adjusting the heating power of the phase change reactor 13, the peak pressure of the shock wave is controlled, and the duration of the shock wave is controlled by adjusting the aperture of the barrel 18. Shock waves with different peak loads and long durations can be obtained.

[0144] Third, this application adjusts the width of the ground shock wave by combining stress wave lenses, which can convert the planar ground shock wave into ground impact loads of different ranges, thereby expanding the controllable range of the impact loading spatial form.

[0145] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A test apparatus for simulating the effects of ultra-high-speed ground-penetrating impacts, characterized in that, include: The test chamber is used to place the test sample; A static load system is used to apply a static load around the specimen to simulate a geostress environment. A dynamic load system for applying a dynamic impact load to the top of a specimen to simulate ground impact includes: A phase change reactor, equipped with a heating mechanism, a liquid inlet valve, and a gas outlet valve, is used to heat liquid CO2 to a supercritical high-pressure state. The liquid filling module, connected to the liquid inlet valve, is used to fill the phase change reactor with liquid CO2; The barrel, connected to the exhaust valve, has a variable orifice and is used to receive the high-pressure gas released from the phase change reactor and form an approximately planar ground shock wave. The stress wave lens module is tightly installed between the end of the barrel and the top surface of the specimen. It is used to adjust the width of the shock wave through the stress wave lens combination and apply it to the specimen. The control module can control the opening and closing of the liquid inlet valve and the gas outlet valve, can control the peak pressure of the shock wave by adjusting the heating power of the phase change reactor, and can control the duration of the shock wave by adjusting the barrel diameter. The stress wave lens module is cylindrical, and inside it is a convex stress wave lens that can focus the incident ground shock wave and a concave stress wave lens that can diverge the incident ground shock wave. The convex and concave stress wave lenses are separated from each other, and the area outside the convex and concave stress wave lenses is filled with a propagation medium. The combination of the convex and concave stress wave lenses can focus or diverge the ground shock wave, thereby adjusting the width of the ground shock wave.

2. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The stress wave lens module is detachably mounted on the top surface of the sample, and the barrel is mounted on the test chamber with its end tightly attached to the top surface of the stress wave lens module.

3. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The phase change reactor also has monitoring and protection mechanisms, including a safety valve for pressure relief to prevent overpressure and sensors for monitoring the temperature and pressure inside the phase change reactor.

4. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The inner bore of the gun barrel is formed by multiple radially contracting plates along the line, and the contraction of the multiple radially contracting plates is controlled by hydraulic pipes.

5. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The liquid filling module, phase change reactor, and gun barrel are connected sequentially from top to bottom and installed on the top of the test chamber.

6. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The liquid filling module includes a CO2 storage chamber, a high-pressure pump, and a high-pressure liquid CO2 storage tank connected in sequence.

7. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 1, characterized in that: The static load loading system includes hydraulic loading cylinders corresponding to the four sides of the specimen. The hydraulic loading cylinders are installed on the side of the test chamber and the test chamber provides the reaction force. The loading end of the hydraulic loading cylinder is equipped with a pressure head, and the side of the specimen is equipped with a pressure plate. The pressure head can extend into the test chamber and act on the corresponding pressure plate. All hydraulic loading cylinders can apply static load to the four sides of the specimen in a pair-by-pair manner.

8. The experimental apparatus for simulating the effects of ultra-high-speed ground penetration as described in claim 7, characterized in that: The test chamber is equipped with an internal guide rail and a longitudinal guide rail in the front-to-back direction outside the test chamber. The longitudinal guide rail is connected to the internal guide rail. The hydraulic loading cylinder on the side of the longitudinal guide rail is detachably installed on the test chamber through a reaction frame. After the reaction frame is disconnected from the test chamber, it can move back and forth along the longitudinal guide rail. A loading platform is provided on one side of the longitudinal guide rail. The sample can be transferred between the loading platform and the longitudinal guide rail, as well as between the longitudinal guide rail and the internal guide rail.

9. A test method for simulating the effects of ultra-high-speed ground-penetrating impacts, characterized in that, Based on the test apparatus for simulating ultra-high-speed penetration ground impact effect as described in any one of claims 1 to 8, a static load is applied around the specimen to simulate the ground stress environment, and a dynamic impact load is applied to the top of the specimen to simulate ground impact. The method of applying the dynamic impact load is as follows: first, liquid CO2 is quantitatively charged into the phase change reactor, then the liquid CO2 is heated to a supercritical high-pressure state and the peak pressure of the ground impact wave is controlled by adjusting the heating power. When the phase change reactor reaches the preset peak pressure, the gas outlet valve of the phase change reactor is opened, so that the high-pressure gas released by the phase change reactor enters the gun barrel and forms an approximately planar ground impact wave. After the ground impact wave width is adjusted by the stress wave lens combination, it acts on the specimen. The duration of the ground impact wave is controlled by pre-adjusting the gun barrel aperture.

10. The test method for simulating the effects of ultra-high-speed ground penetration as described in claim 9, characterized in that, The method of controlling the peak pressure of the shock wave by adjusting the heating power is as follows: While heating the phase change reactor to induce a phase change of liquid CO2, the temperature and pressure changes inside the phase change reactor are monitored in real time. Helmholtz free energy of supercritical CO2 based on the Span-Wagner equation The calculation formula is （1） in, To reduce density, there are , This represents the actual density of CO2 inside the phase change reactor. This is the critical density of CO2; The ratio of the critical temperature to the actual temperature is given by: , This is the critical temperature for CO2. This represents the actual temperature of CO2 inside the phase change reactor. It is the gas constant; Let Helmholtz free energy be the dimensionless energy of a gas assuming it is perfectly ideal and free from intermolecular interactions. The dimensionless Helmholtz free energy is the residual portion produced during the CO2 phase transition process. For the Helmholtz free energy of an ideal gas, This refers to the residual Helmholtz free energy generated during the phase transition process; According to formula (1), in the supercritical CO2 phase transition process, the pressure-related quantities The relationship between temperature and the equation is: （2） in, The residual dimensionless Helmholtz free energy pair The partial derivatives are expressed by the following formula. （3） in, ; The macroscopic volumetric properties of supercritical CO2 at low density or far from the critical state are characterized by the basic polynomial. Characterizing the fluid properties of supercritical CO2 in a high-density state, with high-density index correction; The Gaussian correction term characterizes the drastic property changes exhibited by supercritical CO2 near the critical point. Characterizes the nonanalytic singular behavior of supercritical CO2 near the critical point; , , , , , , , , , , , , , These are constants obtained experimentally under the supercritical state of CO2; Considering the constant volume and gas mass within the phase change reactor, the relationship between the pressure increase rate and temperature is: （4） Combining formulas (2) to (4), the heating power is adjusted by PID control to change the temperature inside the phase change reactor, thereby achieving precise control of the CO2 pressure inside the phase change reactor.

11. The test method for simulating the effects of ultra-high-speed ground penetration as described in claim 10, characterized in that, Calculate the weight of liquid CO2 charged into the phase change reactor. The method is: Based on the peak shock wave pressure determined by the experimental design, and using the similarity criterion, the CO2 filling volume was established. Mapping relationship with peak pressure of ground shock wave （5） in, The energy conversion efficiency coefficient. To calculate the load scaling ratio based on the similarity criterion, This represents the actual density of CO2 inside the phase change reactor. This refers to the volume of the phase change reactor.

12. The test method for simulating the impact effect of ultra-high-speed ground penetration as described in claim 9, characterized in that, The method for determining the bore diameter of a gun barrel is as follows: The process of releasing high-pressure gas from the phase change reactor is considered an isentropic expansion process. The gas pressure inside the reactor gradually decreases over time. Based on the theory of compressible gas flow, the mass flow rate inside the phase change reactor is expressed as: （6） in, The mass flow rate of the gas released through the exhaust valve and the gun barrel. For flow coefficient, This is the effective cross-sectional area of ​​the gun barrel. For the local speed of sound, This is the specific heat ratio of CO2; When the pressure inside the phase change reactor meets the critical flow condition, the high-pressure supercritical gas forms a confined jet flow within the outlet valve. The relationship between the gas release rate and the pressure evolution process can be obtained from mass conservation. （7） in, This represents the actual volume of supercritical CO2. Combining formulas (6) and (7) with the isentropic relationship, the pressures on the phase change reactor and the gun barrel are obtained. The decay equation over time is: （8） in, The constants related to the volume of the phase change reactor, gas properties, and temperature are expressed as follows: （9） Under the condition that the volume of the phase change reactor is constant, the duration of the ground shock wave is positively correlated with the release rate of the high-pressure gas in the phase change reactor and negatively correlated with the effective cross-sectional area of ​​the gun barrel. Combining formulas (8) and (9) and the required duration of the ground shock wave, the diameter of the gun barrel is determined.

13. The test method for simulating the impact effect of ultra-high-speed ground penetration as described in claim 9, characterized in that, The method for determining the relevant parameters of a stress wave lens is as follows: A combination of a convex stress wave lens and a concave stress wave lens is used, with a propagation medium filling the space between and around the convex and concave stress wave lenses. Let the focal length of the convex stress wave lens be... The focal length of the stress wave concave lens is The convex stress wave lens and the concave stress wave lens are coaxial and spaced apart. For a collimated wave to remain collimated after passing through a convex stress wave lens and a concave stress wave lens, the following condition must be met: （10） Let the beamwidth of the input shock wave be... The output shock beam width is The wavefront curvature control factor of the stress wave lens in the straight wave range. Represented as or (11) Let the material density and impedance of the propagation medium be respectively... , The material density, curvature, and impedance of the stress wave convex lens are respectively... , , The material density, curvature, and impedance of the stress wave concave lens are respectively... , , The relationship between the focal lengths of the two lenses is expressed as follows: （12） （13） The beam width of the input shock wave is determined by the bore diameter of the gun barrel. The output shock beam width is determined according to the experimental requirements. ,Compare and ,when > Then, the convex lens and concave lens of the stress wave are arranged vertically. < Then, the concave stress wave lens and the convex stress wave lens are arranged vertically, first according to the wavefront curvature control factor. Sure , And then according to and Determine the specific parameters of the propagation medium, the convex lens of the stress wave, and the concave lens of the stress wave.

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