Calculation method of damage factor of rock and soil specimens in freeze-thaw cycle test device with adjustable temperature change rate

Abstract

The present invention relates to a freeze-thaw cycle test device with adjustable temperature change rate and a damage factor calculation method. The device includes: a base, which is used to place a rock and soil sample when performing a freeze-thaw cycle test; a heating adjustment mechanism, which is arranged at the periphery of the base and is suitable for being at least partially thermally coupled to the rock and soil sample when performing a freeze-thaw cycle test, the heating adjustment mechanism includes a plurality of coupled heating plates and is suitable for forming a multi-stage heating rate adjustment for the rock and soil sample at least through the plurality of heating plates; a freezing adjustment mechanism, which is arranged outside the heating adjustment mechanism and is suitable for being at least partially thermally coupled to at least one of the rock and soil sample and the heating adjustment mechanism when performing a freeze-thaw cycle test, the freezing adjustment mechanism includes a plurality of coupled freezing tubes and is suitable for forming a multi-stage cooling rate adjustment for the rock and soil sample at least through the plurality of freezing tubes. In this way, the adjustment of the temperature change rate in the geotechnical mechanics freeze-thaw cycle test can be achieved, so that the device can simulate the actual engineering temperature change environment for testing, thereby improving the applicability of the device.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass testing, in particular to a rock and soil mechanics freeze-thaw cycle test, an acoustic emission test and damage detection, and specifically to a method for calculating a damage factor of a rock and soil sample in a freeze-thaw cycle test device with an adjustable temperature change rate. Background Art

[0002] In high altitude and high latitude areas, rocks contain abundant crystalline ice. With the increase of human activities in this area, the requirements for the bearing capacity of frozen rock mass are becoming higher and higher. In order to carry out engineering operations safely and efficiently in permafrost areas, it is of great engineering value to study the damage evolution law of ice rock under freeze-thaw cycle conditions.

[0003] In traditional freeze-thaw cycle test devices, the temperature change rate adjustment range is limited, and the entire sample is in the same temperature change environment, which is out of engineering practice. At the same time, the existing device cannot detect the crack extension of the sample during the freeze-thaw cycle, which is not conducive to analyzing the failure mechanism of the sample and hinders the laboratory results from guiding the design of engineering solutions.

[0004] In addition, how to calculate the damage factor of rock in a single freeze-thaw cycle is a difficulty in the current freeze-thaw damage analysis. In the current rock and soil freeze-thaw cycle test, the number of freeze-thaw cycles of the sample in the freeze-thaw chamber is first set; then a complete freeze-thaw cycle test is carried out; finally, the sample is taken out for damage detection. There are two disadvantages to such damage analysis: first, with the increase of the number of freeze-thaw cycles, the damage factor of a single cycle shows a nonlinear decreasing trend, and it is difficult for existing methods to calculate rock damage in the early stage of the freeze-thaw cycle; second, the existing method requires multiple samples to be tested with different numbers of cycles to obtain the expected damage evolution law, but the rock has a certain discreteness, which will produce a large error in the calculation of the damage factor.

[0005] Therefore, it is very important to study a new test device and damage factor calculation method. Summary of the invention

[0006] In view of the shortcomings of the prior art, the main purpose of the present invention is to provide a method for calculating the damage factor of rock and soil samples in a freeze-thaw cycle test device with an adjustable temperature change rate, so as to solve the problems in the prior art that the temperature change rate adjustment range of the equipment is low and the single freeze-thaw damage factor cannot be calculated.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention proposes a freeze-thaw cycle test device with adjustable temperature change rate, comprising: a base for placing a rock and soil sample when conducting the freeze-thaw cycle test; a heating adjustment mechanism, which is arranged on the periphery of the base and is suitable for being at least partially thermally coupled to the rock and soil sample when conducting the freeze-thaw cycle test, and the heating adjustment mechanism includes a plurality of heating plates coupled in sequence and is suitable for forming a multi-stage heating rate adjustment for the rock and soil sample at least through the plurality of heating plates; and a freezing adjustment mechanism, which is arranged outside the heating adjustment mechanism and is suitable for being at least partially thermally coupled to at least one of the rock and soil sample and the heating adjustment mechanism when conducting the freeze-thaw cycle test, and the freezing adjustment mechanism includes a plurality of freezing tubes coupled in sequence and is suitable for forming a multi-stage cooling rate adjustment for the rock and soil sample at least through the plurality of freezing tubes.

[0009] In some embodiments, at least one of the levels of the multi-stage temperature increase rate adjustment and the levels of the multi-stage temperature decrease rate adjustment is adjustable.

[0010] In some embodiments, the heating adjustment mechanism comprises:

[0011] A plurality of the heating plates are arranged in a circumferential direction on the periphery of the base;

[0012] a plurality of heater patch switches, wherein a switch in the plurality of heater patch switches matches a corresponding heater patch in the plurality of heater patches; and

[0013] The heating power supply is electrically coupled to the plurality of heating plates and the plurality of heating plate switches through wires to form the multi-stage heating rate regulation.

[0014] In some embodiments, the heating adjustment mechanism further comprises:

[0015] A heating patch is circumferentially arranged on the inner side of the plurality of heating plates and is at least partially attached to the outer surface of the geotechnical sample when the freeze-thaw cycle test is performed.

[0016] In some embodiments, the plurality of heating plates include heating plate No. 1, heating plate No. 2, heating plate No. 3, heating plate No. 4, heating plate No. 5 and heating plate No. 6, wherein heating plate No. 1, heating plate No. 2, heating plate No. 3, heating plate No. 4, heating plate No. 5 and heating plate No. 6 are arranged sequentially along the height direction.

[0017] In some embodiments, the plurality of heating plate switches include heating plate switch No. 1, heating plate switch No. 2, heating plate switch No. 3, heating plate switch No. 4, heating plate switch No. 5 and heating plate switch No. 6, wherein the heating plate switch No. 1, the heating plate switch No. 2, the heating plate switch No. 3, the heating plate switch No. 4, the heating plate switch No. 5 and the heating plate switch No. 6 are arranged sequentially along the height direction and are correspondingly coupled to the heating plate No. 1, the heating plate No. 2, the heating plate No. 3, the heating plate No. 4, the heating plate No. 5 and the heating plate No. 6 to form a three-stage heating rate adjustment.

[0018] In some embodiments, the cryo-regulation mechanism comprises:

[0019] A plurality of the freezing tubes are annularly arranged on the periphery of the plurality of the heating plates;

[0020] a plurality of cryotube valves, wherein valves in the plurality of cryotube valves match corresponding cryotubes in the plurality of cryotubes; and

[0021] The freezing pump is fluidically coupled to the plurality of freezing pipe valves via an inlet pipe, and is fluidically coupled to the plurality of freezing pipes via a return pipe, so as to form the multi-stage cooling rate regulation.

[0022] In some embodiments, the cryo-regulation mechanism further comprises:

[0023] The freezing patch is circumferentially arranged on the inner side of the plurality of freezing tubes and attached to the outer surface of the plurality of heating plates.

[0024] In some embodiments, the plurality of cryotubes include cryotube No. 1, cryotube No. 2, cryotube No. 3, cryotube No. 4, cryotube No. 5 and cryotube No. 6, wherein the cryotube No. 1, the cryotube No. 2, the cryotube No. 3, the cryotube No. 4, the cryotube No. 5 and the cryotube No. 6 are arranged sequentially along the height direction.

[0025] In some embodiments, the plurality of cryotube valves include cryotube valve No. 1, cryotube valve No. 2, cryotube valve No. 3, cryotube valve No. 4, cryotube valve No. 5 and cryotube valve No. 6, wherein the cryotube valve No. 1, the cryotube valve No. 2, the cryotube valve No. 3, the cryotube valve No. 4, the cryotube valve No. 5 and the cryotube valve No. 6 are arranged sequentially along the height direction and are correspondingly coupled to the cryotube No. 1, the cryotube No. 2, the cryotube No. 3, the cryotube No. 4, the cryotube No. 5 and the cryotube No. 6 to form a three-stage cooling rate regulation.

[0026] In some embodiments, at least one temperature sensor is further included, and at least one of the temperature sensors is mounted on the bottom of the base.

[0027] In some embodiments, a vertical notch is provided on the heating patch, and two fixing plates are provided at the position of the vertical notch. Both fixing plates have circular holes, which are suitable for a pre-tightening bolt to pass through the circular hole and be fixed by a pre-tightening nut.

[0028] In some embodiments, the test device further comprises at least one acoustic emission probe, one end of each of the at least one acoustic emission probe is connected and fixed to the heating adjustment mechanism, and the other end passes through the freezing adjustment mechanism and is arranged on the outside of the rock and soil sample.

[0029] In some embodiments, the liquid inlet pipe and the liquid return pipe are both connected with at least one conduit, one end of which is connected with the liquid inlet pipe or the liquid return pipe, and the other end of which passes through the freezing adjustment mechanism and is arranged on the outside of the geotechnical sample.

[0030] In some embodiments, it also includes a preload spring, a force gauge and a grating displacement meter, wherein the preload spring is arranged between the two fixing plates and is sleeved on the preload bolt, the force gauge is arranged on the outer side of one of the fixing plates and is fastened by the fastening nut, and the grating displacement meter is installed on one of the fixing plates.

[0031] The present invention also proposes a method for calculating the damage factor of a rock and soil sample based on the above-mentioned test device, comprising the following steps:

[0032] S10: Test measurement: including measuring the radius r and height h of the rock and soil sample;

[0033] S20: Test preparation: firstly, the heating patch is placed on the rock and soil sample, then the pre-tightening nut is screwed to fix it, and finally the value of the grating displacement meter is reset to zero and the value F0 of the dynamometer is recorded;

[0034] S30: performing a freeze-thaw cycle test, and recording the value S of the grating displacement meter, the value F of the dynamometer, and the time t during the test;

[0035] S40: Calculate the hoop stress of the rock and soil sample and hoop strain , where the hoop stress The expression is: , the hoop strain The expression is: ;

[0036] S50: hoop strain is the X-axis, hoop stress The Y axis is used to draw the freeze-thaw cycle loading and unloading curve, where the hoop strain The increasing curve is the heating curve, and the hoop strain The decreasing curve is the freezing curve;

[0037] S60: Calculate the dissipated energy density U of the rock and soil sample d : The dissipated energy density U d is the area of ​​the closed region formed by the heating curve, the freezing curve and the X-axis;

[0038] S70: Obtaining the elastic modulus E and damping coefficient C of the rock and soil sample by curve fitting, wherein the fitting formula of the freezing curve is: , the fitting formula of the heating curve is: ;

[0039] S80: Calculate the damping energy density U of the rock and soil sample c :Including hoop strain is the X-axis, damping stress As the Y axis, draw a curve, the closed area formed by the curve and the X axis is the damping energy density U c ,in is the strain rate;

[0040] S90: Calculate the damage factor of the rock and soil sample :

[0041]

[0042] Where i is the i-th freeze-thaw cycle, n is the total number of cycles, is the i-th dissipated energy density, is the i-th damping energy density, is the damage energy density of the ith time, expressed as .

[0043] The beneficial effects of the present invention relative to the prior art are:

[0044] The present invention proposes a method for calculating the damage factor of rock and soil samples of a freeze-thaw cycle test device with adjustable temperature change rate, wherein the device realizes the adjustment of the temperature change rate in the rock and soil mechanics freeze-thaw cycle test through the cooperation of a base, a heating adjustment mechanism, and a freezing adjustment mechanism, so that the device can simulate the actual engineering temperature change environment for testing, thereby improving the applicability of the device.

[0045] The heating adjustment mechanism proposed by the present invention has a simple structural design and can realize the adjustment of multi-stage heating rate, thereby reducing the workload of staff and improving work efficiency.

[0046] The refrigeration adjustment mechanism proposed by the present invention has a simple structural design and can realize multi-stage cooling rate adjustment, thereby reducing the workload of staff and improving work efficiency.

[0047] The present invention realizes the multi-stage heating rate adjustment of the device through the cooperation of the heating plate, the heating plate switch, the heating patch and the heating power supply. The heating power supply is started to transmit electricity to the heating plate through the wire. The heating plate heats the rock and soil sample through the heating patch. At the same time, the staff controls the multi-level heating rate adjustment by controlling the heating plate switch.

[0048] The present invention realizes the multi-stage cooling rate adjustment of the device through the cooperation of the freezing tube, the freezing tube valve, the freezing patch and the freezing pump. The freezing pump is started to allow the coolant to enter the freezing tube through the liquid inlet pipe. The freezing tube cools the rock and soil samples through the freezing patch. At the same time, the staff controls the multi-level cooling rate adjustment by controlling the freezing tube valve.

[0049] The present invention is combined with an acoustic emission probe for acoustic monitoring of rock and soil damage, and is integrated into an integrated arrangement. It can not only accurately control parameters such as temperature and humidity through freeze-thaw cycles, thereby simulating real natural environmental conditions and making the test results more accurate and reliable, but also can monitor the acoustic emission signals inside the rock and soil samples in real time through the probe, and obtain crack acoustic signals, so as to observe the development of internal cracks, and also can evaluate the damage of the rock and soil samples under freeze-thaw conditions. The two complement and verify each other, further improving the applicability of the device.

[0050] The damage factor calculation method proposed in the present invention fully considers the influence of the damping effect on energy dissipation, and further decomposes the dissipated energy into the superposition of two energies, one is the damage energy that causes damage to the sample, and the other is the damping energy that does not cause damage, thereby improving the calculation accuracy of the damage factor.

[0051] The present invention can also calculate the damage factor under each freeze-thaw cycle condition, can accurately reflect the evolution law of the freeze-thaw cycle damage factor of the geotechnical specimens, and significantly reduce the number of geotechnical specimens in the test and reduce the systematic error of the damage factor calculation caused by the discreteness of the geotechnical specimens.

[0052] It should be understood that the implementation of any embodiment of the present invention does not mean that multiple or all of the above-mentioned beneficial effects must be possessed or achieved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0054] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment in size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0055] Figure 1 It is a schematic diagram of the three-dimensional structure of a freeze-thaw cycle test device with adjustable temperature change rate according to some embodiments of the present invention;

[0056] Figure 2 for Figure 1 A top view of

[0057] Figure 3 for Figure 1 A partial cross-sectional view of

[0058] Figure 4 A schematic diagram of three-stage heating rate adjustment of a heating adjustment mechanism in some embodiments of the present invention;

[0059] Figure 5 A schematic diagram of three-stage cooling rate adjustment of a freezing adjustment mechanism in some embodiments of the present invention;

[0060] Figure 6 It is a schematic diagram of the installation of the temperature sensor of some embodiments of the present invention;

[0061] Figure 7 A schematic diagram of overall force analysis of a heating patch according to some embodiments of the present invention;

[0062] Figure 8 It is a schematic diagram of the refrigeration stress analysis of the rock and soil sample of the present invention;

[0063] Fig. 9 It is a schematic diagram of the rock and soil sample heating stress analysis of the present invention;

[0064] Fig.10 The schematic diagram of energy partitioning for freeze-thaw cycle experiment using the test device of the present invention is shown in FIG.

[0065] Markings in the figure:

[0066] 1-base; 2-heating adjustment mechanism; 201-heating plate; 2011-No. 1 heating plate; 2012-No. 2 heating plate; 2013-No. 3 heating plate; 2014-No. 4 heating plate; 2015-No. 5 heating plate; 2016-No. 6 heating plate; 202-heating patch; 203-heating plate switch; 2031-No. 1 heating plate switch; 2032-No. 2 heating plate switch; 2033-No. 3 heating plate switch; 2034-No. 4 heating plate switch; 2035-No. 5 heating plate switch; 2036-No. 6 heating plate switch; 204-heating power supply; 205-fixed plate; 3-freezing adjustment mechanism; 301-freezing tube; 3011-No. 1 freezing tube; 3012-No. 2 freezing tube Freezing pipe; 3013-No. 3 freezing pipe; 3014-No. 4 freezing pipe; 3015-No. 5 freezing pipe; 3016-No. 6 freezing pipe; 302-freezing patch; 303-freezing pipe valve; 3031-No. 1 freezing pipe valve; 3032-No. 2 freezing pipe valve; 3033-No. 3 freezing pipe valve; 3034-No. 4 freezing pipe valve; 3035-No. 5 freezing pipe valve; 3036-No. 6 freezing pipe valve; 304-freezing pump; 4-temperature sensor; 5-acoustic emission probe; 6-wire; 7-conduit; 8-liquid inlet pipe; 9-liquid return pipe; 10-rock and soil sample; 11-pre-tightening bolt; 12-pre-tightening nut; 13-pre-tightening spring; 14-dynamometer; 15-grating displacement meter.

[0067] In the various drawings, the same or corresponding symbols indicate the same or corresponding parts. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with the embodiments and drawings. Here, the illustrative embodiments of the present invention and their description are used to explain the present invention, but are not intended to limit the present invention.

[0069] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "coupled", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] It should be understood that the terms "include / comprise", "consist of..." or any other variations are intended to cover non-exclusive inclusion, so that a product, device, process or method that includes a series of elements includes not only those elements, but also may include other elements not explicitly listed when necessary, or also includes elements inherent to such product, device, process or method. In the absence of more restrictions, the elements defined by the sentence "include / comprise...", "consist of..." do not exclude the presence of other identical elements in the product, device, process or method that includes the elements.

[0071] It is also necessary to understand that terms such as "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device, component or structure must have a specific direction, be constructed or operate in a specific direction, and should not be understood as a limitation on the present invention.

[0072] In addition, the terms "number one", "number two", "number three", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "number one", "number two", "number three" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0073] The implementation of the present invention is described in detail below in conjunction with preferred embodiments.

[0074] like Figures 1 to 6As shown, the present invention proposes a freeze-thaw cycle test device with adjustable temperature change rate, which includes a base 1, a heating adjustment mechanism 2 and a freezing adjustment mechanism 3. The base 1 is a circular base, which is suitable for placing a rock and soil sample 10 when performing a freeze-thaw cycle test; rock and soil can be divided into categories such as rock, gravel soil, sandy soil, silt, clay soil and special soil. Accordingly, the rock and soil sample 10 may include one or more of a rock sample and a soil sample. Among them, the rock sample may include hard (hard rock) and sub-hard (soft rock); the soil sample may include weakly connected, loose and unconnected soil and soil with special composition, structure, state and properties. The heating regulating mechanism 2 is arranged on the periphery of the base 1, and is suitable for being at least partially thermally coupled to the geotechnical sample 10 when performing a freeze-thaw cycle test. The heating regulating mechanism 2 includes a plurality of heating plates 201 coupled in sequence and is suitable for forming a multi-stage heating rate adjustment for the geotechnical sample 10 at least through the plurality of heating plates 201; the freezing regulating mechanism 3 is arranged on the outside of the heating regulating mechanism 2, and is suitable for being at least partially thermally coupled to at least one of the geotechnical sample 10 and the heating regulating mechanism 2 when performing a freeze-thaw cycle test. The freezing regulating mechanism 3 includes a plurality of freezing tubes 301 coupled in sequence and is suitable for forming a multi-stage cooling rate adjustment for the geotechnical sample 10 at least through the plurality of freezing tubes 301.

[0075] The present invention realizes the adjustment of the multi-stage temperature change rate of the rock and soil sample 10 in the rock and soil mechanics freeze-thaw cycle test through the mutual cooperation of the base 1, the heating adjustment mechanism 2 and the freezing adjustment mechanism 3, so that the device can simulate the temperature change environment in the actual engineering, which is helpful to more comprehensively explore the performance changes of the rock and soil samples under different freeze-thaw conditions.

[0076] In some embodiments, see Figures 1 to 4 The multiple heating plates 201 are all in annular shape, annularly arranged on the periphery of the base 1, and are suitable for being sleeved on the periphery of the rock and soil sample 10 during the freeze-thaw cycle test, and are used to perform multi-level temperature increase heating on the rock and soil sample 10.

[0077] In some embodiments, the heating adjustment mechanism 2 further includes a plurality of heating plate switches 203 and a heating power source 204. The switches in the plurality of heating plate switches 203 match the corresponding heating plates in the plurality of heating plates 201, so as to control the on and off of the corresponding heating plates 201 by turning the heating plate switches 203 off or on, thereby adjusting the working states of the plurality of heating plates 201. The heating power source 204 is electrically coupled to the plurality of heating plates 201 and the plurality of heating plate switches 203 through the wire 6, so as to form a multi-stage heating rate adjustment.

[0078] In some embodiments, see Figures 1 to 4The heating adjustment mechanism 2 further includes a heating patch 202, which is annular and annularly arranged inside the plurality of heating patches 201, and at least partially attached to the outer surface of the geotechnical sample 10 during the freeze-thaw cycle test. The heating patch 202 is arranged to expand its contact area with the geotechnical sample 10, so that heat can be transferred from the heating patch 202 to the surface of the geotechnical sample 10 by heat conduction, and gradually penetrate into the sample.

[0079] The present invention can directly heat the rock and soil sample 10 through the heating plate 201, and can also further perform thermal conduction heating by setting a heating patch 202, or heat it through other media except the heating patch 202. The present invention does not limit the specific heating method.

[0080] It should be understood that the present invention does not specifically limit the models of the heating plate 201, the heating patch 202, the heating plate switch 203, the heating power supply 204 and the wire 6, as long as they meet the actual use requirements.

[0081] The present invention realizes the multi-stage heating rate adjustment of the device by cooperating multiple heating plates 201, heating patches 202, multiple heating plate switches 203 and a heating power supply 204. The staff starts the heating power supply 204 so that the electricity is transmitted to the heating plate 201 through the wire 6. The heating plate 201 transmits the heat to the heating patch 202, so that the heating patch 202 heats the rock and soil sample 10 on the base 1. At the same time, the staff adjusts the multi-stage heating rate by controlling the opening or closing of multiple heating plate switches 203.

[0082] In some embodiments, see Figure 1 , Figure 2 , Figure 3 as well as Figure 5 The multiple freezing tubes 301 are all in a circular shape and are annularly arranged on the outside of the heating regulating mechanism 2, such as the outside of multiple heating plates 201, and are suitable for thermally coupling to the geotechnical sample 10 and / or the heating regulating mechanism 2 during the freeze-thaw cycle test, so as to directly or indirectly perform multi-level cooling of the geotechnical sample 10.

[0083] In some embodiments, the freezing adjustment mechanism 3 further includes a plurality of freezing pipe valves 303 and a freezing pump 304. The valves in the plurality of freezing pipe valves 303 match the corresponding freezing pipes in the plurality of freezing pipes 301, so as to control the opening and closing of the corresponding freezing pipes 301 by turning the freezing pipe valves 303 on or off, thereby adjusting the working state of the plurality of freezing pipes 301. The freezing pump 304 is fluidically coupled to the plurality of freezing pipe valves 303 via the liquid inlet pipe 8, and is fluidically coupled to the plurality of freezing pipes 301 via the liquid return pipe 9, so as to form a multi-stage cooling rate adjustment.

[0084] In some embodiments, see Figure 1 , Figure 2 , Figure 3 as well as Figure 5 The freezing adjustment mechanism 3 further includes a freezing patch 302, which is in a circular ring shape and is annularly arranged on the inner side of the plurality of freezing tubes 301, such as the outer surface of the plurality of heating plates 201 or the outer surface of the geotechnical sample 10. The freezing patch 302 is arranged to expand its contact area with the geotechnical sample 10, so that low heat or cold can be directly or indirectly transferred from the freezing patch 302 to the surface of the geotechnical sample 10 by heat conduction, and gradually extend into the interior of the sample.

[0085] The present invention can directly cool the rock and soil sample 10 through the freezing tube 301, and can also further perform heat conduction cooling by setting a freezing patch 302, or cool it through other media except the freezing patch 302. The present invention does not limit the specific cooling method.

[0086] It should be understood that the present invention does not make any specific restrictions on the models of the freezing tube 301, freezing patch 302, freezing tube valve 303, freezing pump 304, liquid inlet pipe 8 and liquid return pipe 9, as long as they meet actual usage requirements.

[0087] The present invention realizes the adjustment of the multi-stage cooling rate of the device through the cooperation of multiple freezing tubes 301, freezing patches 302, multiple freezing tube valves 303 and freezing pumps 304. The staff starts the freezing pump 304 to allow the coolant to enter the freezing tube 301 through the liquid inlet pipe 8. The freezing tube 301 transfers low heat or coldness to the freezing patch 302, so that the freezing patch 302 cools the rock and soil sample 10 on the base 1. At the same time, the staff adjusts the multi-stage cooling rate by controlling the opening or closing of multiple freezing tube valves 303.

[0088] In the present invention, at least one of the levels of the multi-stage heating rate regulation and the multi-stage cooling rate regulation is adjustable. For example, the levels of the multi-stage heating rate regulation are two-level, three-level or other levels, and / or the levels of the multi-stage cooling rate regulation are two-level, three-level or other levels. The multi-stage temperature change rate regulation formed by the present invention helps to more comprehensively understand the thermal properties of rock and soil, improve test efficiency, and provide strong support for engineering design. This embodiment is preferably three-level heating rate regulation and three-level cooling rate regulation, and the three-level heating rate regulation and three-level cooling rate regulation are described in detail below.

[0089] In one exemplary embodiment, see Figure 3 , Figure 4The plurality of heating plates 201 include a first heating plate 2011, a second heating plate 2012, a third heating plate 2013, a fourth heating plate 2014, a fifth heating plate 2015 and a sixth heating plate 2016, wherein the first heating plate 2011, the second heating plate 2012, the third heating plate 2013, the fourth heating plate 2014, the fifth heating plate 2015 and the sixth heating plate 2016 are arranged in sequence along the height direction. The plurality of heating plates 201 can be directly arranged on the outer surface of the geotechnical sample 10, or can be arranged on the outer surface of the heating patch 202, so as to heat the geotechnical sample 10 at different levels.

[0090] Continue to see Figure 4 , the plurality of heating plate switches 203 include a first heating plate switch 2031, a second heating plate switch 2032, a third heating plate switch 2033, a fourth heating plate switch 2034, a fifth heating plate switch 2035 and a sixth heating plate switch 2036, wherein the first heating plate switch 2031, the second heating plate switch 2032, the third heating plate switch 2033, the fourth heating plate switch 2034, the fifth heating plate switch 2035 and the sixth heating plate switch 2036 are arranged in sequence along the height direction, and are correspondingly coupled to the first heating plate 2011, the second heating plate 2012, the third heating plate 2013, the fourth heating plate 2014, the fifth heating plate 2015 and the sixth heating plate 2016 to form a three-stage heating rate adjustment.

[0091] In this embodiment, the three-level temperature rise rate regulation has three adjustable levels, namely, the first level temperature rise rate regulation, the second level temperature rise rate regulation and the third level temperature rise rate, wherein every two heating plates 201 and their corresponding heating plate switches 203 are one level, and the level increases by one level for every two additional heating plates 201 and their corresponding heating plate switches 203. For example, the third heating plate switch 2033, the third heating plate 2013, the fourth heating plate switch 2034 and the fourth heating plate 2014 form the first level temperature rise rate regulation; the second heating plate switch 2032, the second heating plate 2012, the fifth heating plate switch 2035 and the fifth heating plate 2015 form the second level temperature rise rate regulation; the first heating plate switch 2031, the first heating plate 2011, the sixth heating plate switch 2036 and the sixth heating plate 2016 form the third level temperature rise rate regulation.

[0092] In this embodiment, the levels of the first-level heating rate adjustment, the second-level heating rate adjustment and the third-level heating rate adjustment are increased step by step, that is, the heating rate is accelerated step by step. The staff can manually operate the switch or automatically control the switch according to actual needs, such as using a wireless or wired connection controller for automatic control to perform different levels of heating rate adjustment. It is applicable to many scenarios, and at the same time, in conjunction with the freezing adjustment mechanism 3, the rock and soil sample 10 can be placed in different temperature change environments.

[0093] It should be understood that in the specific implementation process, the staff can add heating plates 201 and heating plate switches 203 according to actual use needs to further improve the level of temperature increase rate regulation. The present invention includes but is not limited to three-level temperature increase rate regulation.

[0094] Continue to see Figure 3 , Figure 5 The plurality of freezing tubes 301 include a first freezing tube 3011, a second freezing tube 3012, a third freezing tube 3013, a fourth freezing tube 3014, a fifth freezing tube 3015 and a sixth freezing tube 3016, wherein the first freezing tube 3011, the second freezing tube 3012, the third freezing tube 3013, the fourth freezing tube 3014, the fifth freezing tube 3015 and the sixth freezing tube 3016 are arranged in sequence along the height direction. The plurality of freezing tubes 301 can be arranged on the outer surface of the geotechnical sample 10, or on the outer surface of the freezing patch 302, so as to cool the geotechnical sample 10 at different levels.

[0095] Continue to see Figure 5 , multiple cryotube valves 303 include cryotube valve No. 1 3031, cryotube valve No. 2 3032, cryotube valve No. 3 3033, cryotube valve No. 4 3034, cryotube valve No. 5 3035 and cryotube valve No. 6 3036, wherein the cryotube valve No. 1 3031, the cryotube valve No. 2 3032, the cryotube valve No. 3 3033, the cryotube valve No. 4 3034, the cryotube valve No. 5 3035 and the cryotube valve No. 6 3036 are arranged sequentially along the height direction, and are correspondingly coupled to the cryotube No. 1 3011, the cryotube No. 2 3012, the cryotube No. 3 3013, the cryotube No. 4 3014, the cryotube No. 5 3015 and the cryotube No. 6 3016 to form a three-stage cooling rate regulation.

[0096] In this embodiment, the three-stage cooling rate regulation has three adjustable levels, namely, the first stage cooling rate regulation, the second stage cooling rate regulation and the third stage cooling rate regulation, wherein every two freezing pipes 301 and their corresponding freezing pipe valves 303 form one level, and the level increases by one level for every two additional freezing pipes 301 and their corresponding freezing pipe valves 303. For example, the third freezing pipe valve 3033, the third freezing pipe 3013, the fourth freezing pipe valve 3034 and the fourth freezing pipe 3014 form the first stage cooling rate regulation; the second freezing pipe valve 3032, the second freezing pipe 3012, the fifth freezing pipe valve 3035 and the fifth freezing pipe 3015 form the second stage cooling rate regulation; the first freezing pipe valve 3031, the first freezing pipe 3011, the sixth freezing pipe valve 3036 and the sixth freezing pipe 3016 form the third stage cooling rate regulation.

[0097] In this embodiment, the levels of the first-level cooling rate adjustment, the second-level cooling rate adjustment and the third-level cooling rate adjustment are increased step by step, that is, the cooling rate is accelerated step by step, and the staff can manually operate the switch or automatically control the switch according to actual needs, such as using a wireless or wired connection controller for automatic control to perform different levels of cooling rate adjustment, which is applicable to many scenarios. At the same time, different levels of heating rate adjustment are combined to realize the adjustment of the temperature change rate in the geotechnical mechanics freeze-thaw cycle test, so that the device can simulate the actual engineering temperature change environment for testing, thereby improving the applicability of the device.

[0098] It should be understood that in the specific implementation process, the staff can add freezing pipes 301 and freezing pipe valves 303 according to actual use needs to further improve the level of cooling rate regulation. The present invention includes but is not limited to three-level cooling rate regulation.

[0099] In some embodiments, the test device further includes at least one acoustic emission probe 5, which can non-destructively evaluate the damage state of the rock and soil based on the acoustic emission detection technology, using the elastic waves (i.e., acoustic emission signals) generated when the rock and soil are damaged or destroyed. Specifically, in geotechnical engineering, when the rock and soil body is subjected to external loads or internal stress changes, microcracks, deformations, or damage may occur inside it. These processes are accompanied by the release of energy and propagate in the form of elastic waves. The acoustic emission probe is placed on the surface or inside the rock and soil body to receive these elastic wave signals. After receiving the elastic wave signal, the acoustic emission probe can convert it into an electrical signal and record it through a corresponding data acquisition system. Subsequently, these electrical signals are processed and analyzed to extract information related to the damage of the rock and soil body. This information includes the amplitude, frequency, waveform characteristics, etc. of the signal, thereby reflecting the location, degree, and type of damage inside the rock and soil body. By analyzing the acoustic emission signal, the damage state of the rock and soil body, such as the extension of cracks, the distribution of damaged areas, etc., can be evaluated, which helps to timely discover potential safety hazards and provide an important basis for the design, construction, and monitoring of geotechnical engineering.

[0100] In one embodiment, the number of acoustic emission probes 5 may be, for example, Figure 1 , Figure 2 The four shown may also be any other suitable number. Figure 1 and Figure 2In the embodiment shown, four acoustic emission probes 5 are evenly arranged on the periphery of the test device, one end of the four acoustic emission probes 5 is connected and fixed to the heating adjustment mechanism 2, and the other end is arranged on the outside of the rock and soil sample 10 through the freezing adjustment mechanism 3, so as to monitor the acoustic emission signal inside the rock and soil sample in real time, obtain the acoustic damage parameters, and then evaluate the damage of the rock and soil sample under the freeze-thaw condition. In addition, the four acoustic emission probes 5 monitor simultaneously along different directions, so as to improve the monitoring accuracy, and when one acoustic emission probe 5 fails or fails, the other acoustic emission probes 5 can still continue to work, so as to ensure the continuity and stability of the device.

[0101] In a preferred embodiment, the heating regulating mechanism 2 and the freezing regulating mechanism 3 for freeze-thaw cycle test can be combined with the acoustic emission probe 5 for acoustic monitoring of rock and soil damage. Specifically, in the freeze-thaw cycle test, the multi-stage heating regulating mechanism 2 and the multi-stage freezing regulating mechanism 3 can simulate the freeze-thaw process under different natural environments, so that the rock and soil samples experience temperature changes similar to those in the actual environment. By accurately controlling parameters such as temperature and humidity, a variety of freeze-thaw conditions can be simulated, so as to comprehensively evaluate the damage of rock and soil samples under different conditions. At the same time, the acoustic emission probe 5 can monitor the acoustic emission signals of rock and soil samples in the freeze-thaw process in real time. These signals contain important information about the degree of damage, location and development trend of damage inside the sample. By analyzing these signals, acoustic damage parameters such as the frequency, amplitude, and duration of acoustic emission events can be obtained, so as to further understand the damage characteristics of rock and soil samples under freeze-thaw conditions.

[0102] The advantage of this integrated design is that it can combine environmental simulation with acoustic monitoring to achieve a comprehensive assessment of the damage of rock and soil samples. On the one hand, by simulating real natural environmental conditions, more accurate and reliable test results can be obtained; on the other hand, through real-time monitoring of the acoustic emission probe, real-time acoustic damage parameters can be obtained, providing an important basis for damage evaluation.

[0103] In this way, the test device has a high degree of applicability and flexibility. It can be used not only for freeze-thaw damage research of geotechnical samples, but also for monitoring geotechnical damage under other environmental conditions. At the same time, by adjusting parameters and configurations, it can adapt to geotechnical samples of different sizes and types to meet different research needs. Moreover, the measured data of the two can complement each other and verify each other, further improving the applicability of this device.

[0104] In some embodiments, the test device further includes a fixing plate 205, which is provided with two pieces and symmetrically mounted on the heating plate 201 or the heating patch 202, and is used to place the heating plate 201 or the heating patch 202 in close contact with the rock and soil sample 10. This embodiment is preferably installed on the heating patch 202, see Figure 1, Figure 2 The circular ring of the heating patch 202 is not closed, and a certain gap is reserved, that is, there is a vertical notch on the heating patch 202. The heating patch 202 is provided with a fixing plate 205 extending outward along both ends of the gap (notch). One end of the fixing plate 205 is connected and fixed to the heating patch 202, and the other end passes through the freezing adjustment mechanism 3 and is arranged on the outside of the rock and soil sample 10.

[0105] Preferably, both fixing plates 205 are provided with circular holes. In the present invention, the fixing plates 205 are tightened by the pre-tightening bolts 11 through the circular holes and the pre-tightening nuts 12, so that the geotechnical sample 10 and the heating patch 202 are closely fitted together. In this embodiment, the pre-tightening bolts 11 and the pre-tightening nuts 12 serve the purpose of applying initial stress.

[0106] In some embodiments, the present invention further includes at least one temperature sensor 4, so as to monitor the temperature of the rock sample 10 placed on the base 1 in real time, and to provide feedback of temperature information at any time, and to operate the switch immediately if an abnormality is encountered. For example, when the value displayed by the temperature sensor 4 reaches the expected value of temperature rise or temperature drop, the heating plate switch 203 corresponding to the heating plate 201 or the freezing pipe valve 303 corresponding to the freezing pipe 301 is turned off.

[0107] In one embodiment, the number of temperature sensors 4 can be, for example, Figure 6 As shown, the five temperature sensors 4 are radially arranged in the same row at the bottom of the base 1. The five temperature sensors 4 are monitored simultaneously to improve the measurement accuracy. When one temperature sensor 4 fails or fails, the other temperature sensors 4 can continue to work, thereby ensuring the continuity and stability of the device.

[0108] In some embodiments, see Figure 1 , Figure 2 At least one conduit 7 is connected to the liquid inlet pipe 8 and the liquid return pipe 9. One end of the conduit 7 is connected to the liquid inlet pipe 8 or the liquid return pipe 9, and the other end passes through the freezing adjustment mechanism 3 and is arranged on the outside of the rock and soil sample 10 to facilitate the external cooling liquid to enter the freezing adjustment mechanism 3 through the conduit 7.

[0109] In some embodiments, see Figure 7 The test device also includes a preload spring 13, a dynamometer 14 and a grating displacement meter 15, wherein the preload spring 13 is arranged between two fixing plates 205 and sleeved on the preload bolt 11. The arrangement of the preload spring 13 can enhance the strain recovery ability of the heating patch 202 and reduce the system error. The dynamometer 14 is arranged on the outside of one of the fixing plates 205 and is fastened by the preload nut 12 to monitor the deformation force generated by the geotechnical sample 10 at different temperatures. The grating displacement meter 15 is installed on one of the fixing plates 205 to measure the circumference change caused by the deformation of the geotechnical sample 10.

[0110] See also Figures 7 to 10 The present invention also proposes a method for calculating the damage factor of a rock and soil sample based on the above-mentioned test device, comprising the following steps:

[0111] S10: Test measurement: including measuring the radius r and height h of the geotechnical sample 10;

[0112] S20: Test preparation: firstly, the heating patch 202 is placed on the rock and soil sample 10, and then the pre-tightening nut 12 is screwed to fix it, and finally the value of the grating displacement meter 15 is reset to zero and the value F0 of the dynamometer 14 is recorded;

[0113] S30: Perform freeze-thaw cycle test, for example, alternately turn on the freezing pump 304 and the heating power supply 204, so that the freezing pipe 301 and the heating plate 201 work alternately, ensure that the rock and soil sample 10 is in a freeze-thaw cycle condition, and record the value S of the grating displacement meter 15, the value F of the dynamometer 14 and the time t during the test;

[0114] S40: Calculation of hoop stress of soil specimen 10 and hoop strain ; See Figure 7 , where the hoop stress The expression is: , hoop strain The expression is: ;

[0115] S50: See Fig.10 , with hoop strain is the X-axis, hoop stress The Y axis is used to draw the freeze-thaw cycle loading and unloading curves, where the curve with increasing hoop strain is the heating curve, and the curve with decreasing hoop strain is the freezing curve;

[0116] S60: Calculate the dissipated energy density U of the soil sample 10 d , see Fig.10 , whose size is equal to the area of ​​the closed region formed by the heating curve, the freezing curve and the X-axis;

[0117] S70: The elastic modulus E and damping coefficient C of the soil sample 10 are obtained by curve fitting, see Figure 8 , Fig. 9 , where the fitting formula of the freezing curve is: , the fitting formula of the heating curve is: ;

[0118] Specifically, during the freezing process: ,in Effective stress, Substituting damping stress into the formula, the fitting formula of the freezing curve is: .

[0119] During heating: , substituting into the formula, the fitting formula of the heating curve is: .

[0120] S80: Calculate the damping energy density U of the soil sample 10 c , see Fig.10 , with hoop strain is the X-axis, damping stress As the Y axis, draw a curve. The area enclosed by the curve and the X axis is the damping energy density U c ,in is the strain rate (first order of strain with respect to time);

[0121] S90: Calculate the damage factor of geotechnical specimen 10 , the damage factor calculation formula is:

[0122] Where i is the i-th freeze-thaw cycle, n is the total number of cycles, is the i-th dissipated energy density, is the i-th damping energy density, is the damage energy density of the ith time, expressed as .

[0123] The damage factor calculation method proposed in the present invention fully considers the influence of the damping effect on energy dissipation, and further decomposes the dissipated energy into the superposition of two energies, one is the damage energy that causes damage to the sample, and the other is the damping energy that does not cause damage, thereby improving the calculation accuracy of the damage factor.

[0124] The present invention also provides a method for using the above-mentioned freeze-thaw cycle test device with adjustable temperature change rate, comprising:

[0125] Step 1: Installation: Place the geotechnical sample 10 on the base 1 and tighten the fixing sheet 205 with bolts so that the geotechnical sample 10 and the heating patch 202 are closely attached to each other;

[0126] Step 2: Cooling, turning on the freezing pump 304, and opening the corresponding freezing pipe valve 303 according to the expected cooling rate to form the first-level cooling rate adjustment, the second-level cooling rate adjustment, and the third-level cooling rate adjustment, so as to facilitate the three-level cooling rate adjustment of the rock and soil sample 10.

[0127] In this step, when the first stage cooling rate is adjusted, the third freezing pipe valve 3033 and the fourth freezing pipe valve 3034 are opened, and the cooling liquid can flow through the third freezing pipe 3013 and the fourth freezing pipe 3014. When the second stage cooling rate is adjusted, the second freezing pipe valve 3032 and the fifth freezing pipe valve 3035 are opened on the basis of the first stage, and the cooling liquid can flow through the second freezing pipe 3012 and the fifth freezing pipe 3015. When the third stage cooling rate is adjusted, the first freezing pipe valve 3031 and the sixth freezing pipe valve 3036 are opened on the basis of the second stage, and the cooling liquid can flow through the first freezing pipe 3011 and the sixth freezing pipe 3016.

[0128] In this step, when the value displayed by the temperature sensor 4 reaches the expected value, the valves in the multiple freezing pipe valves 303 corresponding to the corresponding freezing pipes in the multiple freezing pipes 301 are closed, and when all the coolant in the freezing pipes flows back to the freezing pump 304, the freezing pump 304 is turned off.

[0129] Step 3: Heating, turn on the heating power supply 204, and turn on the corresponding heating plate switch 203 according to the expected heating rate to form the first level heating rate adjustment, the second level heating rate adjustment and the third level heating rate adjustment, so as to facilitate the three-level heating rate adjustment of the rock and soil sample 10.

[0130] In this step, when adjusting the first level of heating rate, the switch 2033 of the third heating plate and the switch 2034 of the fourth heating plate are turned on, and the third heating plate 2013 and the fourth heating plate 2014 are working. When adjusting the second level of heating rate, the switch 2032 of the second heating plate and the switch 2035 of the fifth heating plate are turned on on the basis of the first level, and the second heating plate 2012 and the fifth heating plate 2015 are working. When adjusting the third level of heating rate, the switch 2031 of the first heating plate and the switch 2036 of the sixth heating plate are turned on on the basis of the second level, and the first heating plate 2011 and the sixth heating plate 2016 are working.

[0131] In this step, when the value displayed by the temperature sensor 4 reaches the expected value, the heating power supply 204 is turned off.

[0132] Step 4: Cycle, cycle the test according to the expected test, repeat steps 2 and 3, and record the value of temperature sensor 4 in real time.

[0133] In this step, when an acoustic emission probe 5 is installed on the device, the values ​​of the temperature sensor 4 and the acoustic emission probe 5 need to be recorded simultaneously.

[0134] This method not only improves the flexibility and accuracy of the test, but also improves the test efficiency, repeatability and safety.

[0135] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the damage factor of rock and soil samples in a freeze-thaw cycle test device with adjustable temperature change rate, characterized in that: The freeze-thaw cycle test device comprises: A base (1) for placing a rock and soil sample (10) when performing the freeze-thaw cycle test; a heating adjustment mechanism (2), arranged at the periphery of the base (1) and adapted to be at least partially thermally coupled to the geotechnical sample (10) when the freeze-thaw cycle test is performed, the heating adjustment mechanism (2) comprising a plurality of sequentially coupled heating plates (201) and adapted to form a multi-stage heating rate adjustment for the geotechnical sample (10) at least via the plurality of heating plates (201); and A freezing regulating mechanism (3) is arranged outside the heating regulating mechanism (2) and is adapted to be at least partially thermally coupled to at least one of the geotechnical sample (10) and the heating regulating mechanism (2) when performing the freeze-thaw cycle test, wherein the freezing regulating mechanism (3) comprises a plurality of sequentially coupled freezing tubes (301) and is adapted to form a multi-stage cooling rate regulation for the geotechnical sample (10) at least via the plurality of freezing tubes (301); wherein the heating regulating mechanism (2) comprises: A plurality of heating plates (201) are arranged in a circular manner on the periphery of the base (1); A plurality of heating plate switches (203), wherein the switches of the plurality of heating plate switches (203) match the plurality of heating plates (201); A heating power source (204) is electrically coupled to the plurality of heating plates (201) and the plurality of heating plate switches (203) via a wire (6) to form the multi-stage heating rate adjustment; and A heating patch (202) is circumferentially arranged on the inner side of the plurality of heating patches (201) and is at least partially attached to the outer surface of the rock and soil sample (10) when the freeze-thaw cycle test is performed; a vertical notch is provided on the heating patch (202), two fixing plates (205) are provided at the position of the vertical notch, and circular holes are provided on the two fixing plates (205), suitable for a pre-tightening bolt (11) to pass through the circular hole and be fixed by a pre-tightening nut (12); The freeze-thaw cycle test device further comprises a preload spring (13), a dynamometer (14) and a grating displacement meter (15), wherein the preload spring (13) is arranged between two of the fixing plates (205) and sleeved on the preload bolt (11), the dynamometer (14) is arranged on the outside of one of the fixing plates (205) and is fastened by the preload nut (12), and the grating displacement meter (15) is mounted on one of the fixing plates (205); The method for calculating the damage factor of a rock and soil sample in the freeze-thaw cycle test device with adjustable temperature change rate comprises the following steps: S10: Test measurement: including measuring the radius r and height h of the rock and soil sample (10); S20: Test preparation: first, the heating patch (202) is placed on the rock and soil sample (10), and then the pre-tightening nut (12) is screwed to fix it, and finally the value of the grating displacement meter (15) is reset to zero and the value F0 of the dynamometer (14) is recorded; S30: performing a freeze-thaw cycle test, and recording the value S of the grating displacement meter (15), the value F of the dynamometer (14), and the time t during the test; S40: Calculation of hoop stress in soil specimen (10) and hoop strain , where the hoop stress The expression is: , hoop strain The expression is: ; S50: hoop strain is the X-axis, hoop stress The Y axis is used to draw the freeze-thaw cycle loading and unloading curve, where the hoop strain The increasing curve is the heating curve, and the hoop strain The decreasing curve is the freezing curve; S60: Calculate the dissipated energy density U of the soil specimen (10) d : Dissipated energy density U d The area of ​​the enclosed region formed by the heating curve, the freezing curve and the X-axis; S70: The elastic modulus E and damping coefficient C of the rock and soil sample (10) are obtained by curve fitting, wherein the fitting formula of the freezing curve is: , the fitting formula of the heating curve is: ; S80: Calculate the damping energy density U of the soil specimen (10) c :Including hoop strain is the X-axis, damping stress As the Y axis, draw a curve, the closed area formed by the curve and the X axis is the damping energy density U c ,in is the strain rate; S90: Calculation of damage factors for geotechnical specimens (10) : ； Where i is the i-th freeze-thaw cycle, n is the total number of cycles, is the i-th dissipated energy density, is the i-th damping energy density, is the damage energy density of the ith time, expressed as .

2. The method for calculating the damage factor of rock and soil samples of the freeze-thaw cycle test device with adjustable temperature change rate according to claim 1, characterized in that: At least one of the levels of the multi-stage temperature increase rate adjustment and the levels of the multi-stage temperature decrease rate adjustment is adjustable.

3. The method for calculating the damage factor of rock and soil samples of the freeze-thaw cycle test device with adjustable temperature change rate according to claim 1 is characterized in that: The plurality of heating plates (201) include a first heating plate (2011), a second heating plate (2012), a third heating plate (2013), a fourth heating plate (2014), a fifth heating plate (2015) and a sixth heating plate (2016), wherein the first heating plate (2011), the second heating plate (2012), the third heating plate (2013), the fourth heating plate (2014), the fifth heating plate (2015) and the sixth heating plate (2016) are arranged in sequence along a height direction; and The plurality of heating plate switches (203) include a first heating plate switch (2031), a second heating plate switch (2032), a third heating plate switch (2033), a fourth heating plate switch (2034), a fifth heating plate switch (2035) and a sixth heating plate switch (2036), wherein the first heating plate switch (2031), the second heating plate switch (2032), the third heating plate switch (2033), the fourth heating plate switch (2034), the fifth heating plate switch (2035) and the sixth heating plate switch (2036) are arranged in sequence along a height direction and are correspondingly coupled to the first heating plate (2011), the second heating plate (2012), the third heating plate (2013), the fourth heating plate (2014), the fifth heating plate (2015) and the sixth heating plate (2016) to form a three-stage temperature rise rate adjustment.

4. The method for calculating the damage factor of rock and soil samples of the freeze-thaw cycle test device with adjustable temperature change rate according to claim 1 is characterized in that: The freezing adjustment mechanism (3) comprises: The plurality of freezing tubes (301) are arranged in an annular direction on the periphery of the plurality of heating plates (201); A plurality of freezing pipe valves (303), wherein the plurality of freezing pipe valves (303) match the plurality of freezing pipes (301); A freezing pump (304) is fluidically coupled to the plurality of freezing pipe valves (303) via a liquid inlet pipe (8), and is fluidically coupled to the plurality of freezing pipes (301) via a liquid return pipe (9), so as to form the multi-stage cooling rate regulation; and The freezing patch (302) is circumferentially arranged on the inner side of the plurality of freezing tubes (301) and is attached to the outer surface of the plurality of heating plates (201).

5. The method for calculating the damage factor of rock and soil samples of the freeze-thaw cycle test device with adjustable temperature change rate according to claim 4 is characterized in that: The plurality of freezing tubes (301) include a first freezing tube (3011), a second freezing tube (3012), a third freezing tube (3013), a fourth freezing tube (3014), a fifth freezing tube (3015) and a sixth freezing tube (3016), wherein the first freezing tube (3011), the second freezing tube (3012), the third freezing tube (3013), the fourth freezing tube (3014), the fifth freezing tube (3015) and the sixth freezing tube (3016) are arranged in sequence along a height direction; and The plurality of cryotube valves (303) include a first cryotube valve (3031), a second cryotube valve (3032), a third cryotube valve (3033), a fourth cryotube valve (3034), a fifth cryotube valve (3035) and a sixth cryotube valve (3036), wherein the first cryotube valve (3031), the second cryotube valve (3032), the third cryotube valve (3033), the fourth cryotube valve (3034), the fifth cryotube valve (3035) and the sixth cryotube valve (3036) are arranged sequentially along the height direction and are correspondingly coupled to the first cryotube (3011), the second cryotube (3012), the third cryotube (3013), the fourth cryotube (3014), the fifth cryotube (3015) and the sixth cryotube (3016) to form a three-stage cooling rate regulation.

6. The method for calculating the damage factor of rock and soil samples of the freeze-thaw cycle test device with adjustable temperature change rate according to claim 1 is characterized in that: It also comprises at least one temperature sensor (4), wherein at least one of the temperature sensors (4) is mounted on the bottom of the base (1).

7. The method for calculating the damage factor of rock and soil samples in a freeze-thaw cycle test device with adjustable temperature change rate according to any one of claims 1 to 6, characterized in that: The test device further comprises at least one acoustic emission probe (5), wherein one end of each of the at least one acoustic emission probe (5) is connected and fixed to the heating adjustment mechanism (2), and the other end passes through the freezing adjustment mechanism (3) and is arranged outside the rock and soil sample (10).

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