A down-moving type geologic sample triaxial testing machine and testing method

Abstract

A lower-acting geological sample triaxial testing machine and testing method, relating to a rock mechanics testing technical field.The present application discards the traditional upper pressure operation form, drives the sample axial loading through the lower acting piston rod lifting, greatly widens the sample dismounting operation space, simplifies the clamping process, improves the testing efficiency, can be adapted to the large size geological sample testing scene at the same time, solves the disadvantages of small loading range of traditional equipment and only small sample testing, and simultaneously adopts a double servo valve parallel redundancy driving structure, compared with the traditional single valve control mode, effectively improves the oil supply flow and loading response speed of the hydraulic system, widens the loading rate adjustment range, can meet the rock axial loading test demand of high precision, large load and high speed, and the double valve redundancy layout can also effectively avoid the test interruption problem caused by single valve failure, and guarantees the continuous and stable development of the test.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, and more particularly to a downward-moving triaxial testing machine for geological samples and a testing method thereon. Background Technology

[0002] Rock mass engineering is an important research field in rock mechanics. Triaxial compression testing is an indispensable experimental method for fully understanding the mechanical properties of rocks and evaluating rock mass stability. Triaxial compression testing detects the load-bearing capacity of rocks under multi-directional stress conditions by simultaneously applying axial pressure and confining hydraulic pressure to the specimen. The axial pressure is provided by a compression testing machine, while the confining pressure is applied to the outer periphery of the specimen by independent ultra-high-pressure hydraulic oil. When conducting pore pressure testing, high-pressure fluid is introduced into the pores at both ends of the specimen to achieve pore pressure loading.

[0003] Most existing triaxial testing machines adopt an upward-moving loading structure, where the test load is applied downward by an upper loading cylinder, and the specimen is placed on a fixed base at the bottom. Traditional models have limited axial loading capacity, mostly only capable of performing confining pressure tests on small-sized geological specimens. Many devices are functionally limited and cannot perform pore pressure coupling tests, making it difficult to meet the comprehensive testing needs of large-sized geological specimens. Furthermore, this type of equipment has revealed several shortcomings in practical use:

[0004] Firstly, the core load components such as the upper hydraulic cylinder and force sensor are located above the sample for a long time, which limits the space for sample installation and disassembly and makes the sample loading process cumbersome.

[0005] Secondly, the axial displacement of the sample is measured by the stroke of the upper cylinder. The sensor arrangement is simple, making it difficult to directly obtain the true displacement of the lower end of the sample. The displacement measurement is easily affected by the deformation of the crossbeam and transmission mechanism, making it difficult to guarantee the accuracy of displacement detection.

[0006] Meanwhile, the servo drive circuits of existing triaxial testing machines mostly use a single servo valve to control the actuating cylinder. Under heavy load and high-speed reciprocating loading conditions, the single valve has limited flow output capacity, which cannot meet the requirements of high response and large flow. The adjustment range of the test loading rate is limited, making it difficult to meet the diverse test conditions of geological samples.

[0007] In addition, in traditional triaxial testing systems, when the specimen assembly is subjected to confining pressure and pore pressure coupled tests, the confining pressure medium and pore fluid are introduced into the specimen through corresponding flow channels. The pore fluid path and the confining pressure oil supply path are prone to mutual interference, which directly affects the reliability of the test data.

[0008] Therefore, there is an urgent need to develop a triaxial testing machine for geological samples with a reasonable structure, convenient sample loading, reliable displacement measurement, high-flow-rate high-speed loading, simultaneous confining pressure and pore pressure coupling tests, convenient circumferential strain detection of samples, and stable lifting and lowering operation of the high-pressure cylinder. Summary of the Invention

[0009] To address the above problems, this invention provides a triaxial testing machine and method for geological samples that enables high-flow-rate, high-speed loading, simultaneous confining pressure and pore pressure coupling tests, convenient circumferential strain detection of samples, and stable lifting and lowering operation of the high-pressure cylinder.

[0010] The technical solution of this invention is:

[0011] A downward-moving triaxial testing machine for geological samples, comprising:

[0012] The actuator assembly includes, from bottom to top, an actuator cylinder, a worktable, an actuation hydraulic servo module, and a displacement sensor, which are fixedly connected in sequence.

[0013] The actuating cylinder is equipped with an actuating piston rod, which reciprocates in the vertical direction;

[0014] The worktable is fixedly mounted on the top of the actuating cylinder; a guide sleeve is fixedly mounted in the middle of the worktable, and the top end of the actuating piston rod extends outward from the guide sleeve and slides and guides with the guide sleeve.

[0015] The displacement sensor is installed on the actuating cylinder to detect the extension displacement of the actuating piston rod in real time;

[0016] The actuation hydraulic servo module includes a first servo valve and a second servo valve; the first control port of the first servo valve and the first control port of the second servo valve are respectively connected to the rodless chamber port of the actuation cylinder; the second control port of the first servo valve and the second control port of the second servo valve are respectively connected to the rod chamber port of the actuation cylinder; the signal output terminal of the displacement sensor is connected to the displacement control unit, and the displacement control unit is electrically connected to the control input terminals of the first servo valve and the second servo valve to adjust the movement position and movement speed of the actuation piston rod.

[0017] A sample mounting base is disposed on the top surface of the actuating piston rod, and is raised and lowered by the actuating piston rod; the top surface of the sample mounting base is provided with a sample mounting position for placing the sample assembly; the sample mounting base is provided with a pore flow channel leading to the sample mounting position for pore testing of the sample assembly; the sample mounting base is provided with a confining pressure flow channel leading to the side of the sample mounting position for confining pressure testing of the sample assembly.

[0018] The sample assembly, disposed at the sample mounting position, includes an upper end cap, a rubber sleeve, and a lower end cap;

[0019] The sample is placed between the upper end cap and the lower end cap; the upper end cap and the lower end cap are respectively provided with fluid passage holes to allow fluid to enter the interior of the sample; the rubber sleeve is wrapped around the sample; multiple strain test rings are provided on the outside of the rubber sleeve;

[0020] A high-pressure cylinder includes a high-pressure cylinder body, a high-pressure piston rod, and a force sensor;

[0021] The force sensor is fixedly mounted on the bottom of the high-pressure piston rod;

[0022] The top of the high-pressure piston rod is fixedly connected to the crossbeam via a piston rod connecting plate; the piston rod connecting plate is provided with an upper inlet for the pore; the upper inlet for the pore passes through the piston rod connecting plate, the high-pressure piston rod and the drainage hole on the force sensor in sequence, so that the liquid used for pore testing enters the sample end face through the drainage hole;

[0023] The high-pressure cylinder moves up and down below the crossbeam via a lifting cylinder along the axial direction of the high-pressure piston rod; the side of the high-pressure cylinder is provided with a confining pressure upper inlet; ultra-high pressure hydraulic oil used for confining pressure testing flows into the high-pressure cylinder through the confining pressure upper inlet, thereby entering the vicinity of the sample assembly.

[0024] Specifically, the workbench is equipped with a pair of fixed guide rails;

[0025] The slider on the guide rail is fixedly connected to the side of the mounting connection plate. The mounting connection plate is slid out of the worktable by a pair of guide rails, which facilitates the installation of the sample assembly.

[0026] Specifically, the lifting cylinder includes an electric lifting cylinder, a pneumatic lifting cylinder, or a hydraulic lifting cylinder;

[0027] The cylinder body of the lifting cylinder is fixedly connected to the crossbeam, and the piston rod end is fixedly connected to the high-pressure cylinder body.

[0028] Specifically, the cylinder body of the lifting cylinder is fixedly mounted on the side of the crossbeam (160) via an upper mounting seat and a stationary limiting seat, and the piston rod end is fixedly connected to the high-pressure cylinder body via a fixedly connected cylinder connecting block;

[0029] The side of the stationary limiting seat is provided with a first insertion hole;

[0030] The side of the cylinder connecting block is provided with a second insertion hole that is adapted to the first insertion hole; after the first insertion hole and the second insertion hole are aligned, the cylinder connecting block is fixed to the stationary limiting seat by a pin.

[0031] Specifically, the lifting cylinder is connected to the lifting cylinder valve block, and the lifting cylinder valve block controls the rise or fall of the high-pressure cylinder body;

[0032] The lifting cylinder valve block is equipped with an inlet throttle valve, a manual directional valve, a hydraulic check valve, a one-way throttle valve, an overflow valve, and an emergency stop valve.

[0033] The inlet end of the inlet throttle valve is connected to the inlet port P of the lifting cylinder valve block, and the outlet end is connected to the main oil supply channel of the manual reversing valve.

[0034] The manual directional valve is provided with a main oil supply port and a hydraulic control oil supply port at its outlet end. The main oil supply port is connected to the main oil inlet of the hydraulic control check valve, and the hydraulic control oil supply port is connected to the control oil port of the hydraulic control check valve.

[0035] The oil outlet of the hydraulic control check valve is connected to the oil inlet of the check throttle valve.

[0036] The overflow valve and the emergency stop valve are connected in parallel, and the two ends of the parallel branch are respectively connected to the oil outlet of the one-way throttle valve and the oil return passage.

[0037] The oil outlet of the one-way throttle valve and the oil inlet of the overflow valve are connected to the rod chamber of the lifting cylinder.

[0038] Specifically, the displacement sensor is a magnetostrictive displacement sensor, with its electronic housing fixedly installed at the bottom of the actuating cylinder. The probe extends into the inner cavity of the actuating cylinder and is located inside the actuating piston rod, detecting the extension displacement of the actuating piston rod in real time.

[0039] Specifically, the sample mounting base includes a mounting connection plate, a sample mounting plate, and a strain testing transition plate that are fixedly connected in sequence;

[0040] The mounting plate has a lower inlet on its side; the top surface of the sample mounting plate has a pore outlet adapted to the sample assembly, and the pore outlet is connected to the lower inlet so that fluid can enter the pores of the sample during pore testing.

[0041] Specifically, the sample mounting plate has a confining pressure inlet on its side, and the strain test transition plate has a confining pressure outlet that communicates with the confining pressure inlet. The confining pressure outlet is located on the side of the sample mounting position and is used to allow hydraulic oil to enter around the sample assembly during the confining pressure test.

[0042] A test method for a downward-moving triaxial testing machine for geological samples, comprising the following steps:

[0043] Step 1: Drive the lifting cylinder to raise the high-pressure cylinder to the highest point of its stroke; the cylinder connecting block is rigidly locked to the stationary limit seat (520), and the force sensor is assembled to the lower end of the high-pressure piston rod;

[0044] Step 2: Install the component to be tested into the sample mounting position of the sample mounting base;

[0045] Step 3: Complete the electrical connection of the strain test ring and force sensor.

[0046] Step 4: The actuating piston rod of the actuating cylinder moves upward until the upper end cover of the sample assembly is in contact with the force sensor. When the load feedback from the force sensor reaches 1% of the rated working range, the actuating piston rod stops feeding.

[0047] Step 5: Release the rigid lock between the cylinder connecting block and the stationary limit seat, drive the lifting cylinder downward, and drive the lower end of the high-pressure cylinder to close with the sample mounting plate to form a sealed pressure chamber;

[0048] After the high-pressure cylinder is pressed down to the position, the upper inlet of the high-pressure cylinder is connected to the lower inlet of the sample mounting plate through the inner cavity of the high-pressure cylinder.

[0049] The piston rod connecting plate is provided with an upper inlet of the orifice. The upper inlet of the orifice passes through the piston rod connecting plate, the high-pressure piston rod and the drainage hole on the force sensor in sequence, and is connected to the lower inlet of the orifice.

[0050] Step 6, Confining pressure test

[0051] High-pressure hydraulic oil is introduced into the sealed cavity of the high-pressure cylinder through the upper and lower confining pressure inlets to establish a confining pressure environment around the sample; the emergency stop valve is switched to the right-hand position, and the manual directional valve is kept in the reset right-hand position.

[0052] By gradually increasing the loading pressure of the actuating piston rod, the load signal of the force sensor and the strain test ring data under the corresponding loading pressure are collected to obtain the compressive stress performance parameters of the sample.

[0053] Step 7, Porosity Testing

[0054] Confining hydraulic oil maintaining a certain pressure on the outside of the sample;

[0055] Test fluid is introduced into the upper and lower inlets of the pores and enters the upper and lower ends of the sample; the loading pressure of the actuating piston rod is gradually increased, and the load signal of the force sensor and the strain test annular variable data are collected simultaneously to detect the stress bearing capacity of the sample under the coupled conditions of pore fluid and confining pressure.

[0056] Step 8: After all tests are completed, first completely depressurize the hydraulic pressure in the high-pressure cylinder cavity to zero. After confirming that there is no residual high pressure, drive the lifting cylinder to raise the high-pressure cylinder body to reset.

[0057] Specifically, the lifting cylinder control method includes:

[0058] S100, the lifting cylinder performs an upward movement, the emergency stop valve switches to the working conduction position, and the oil supply passage of the rod chamber of the lifting cylinder is opened; then the reversing valve switches to the upward working position, and the system pressure oil is delivered to the rod chamber of the lifting cylinder through the inlet throttle valve and the A oil port of the manual reversing valve in sequence, driving the lifting cylinder to move upward; among them, the inlet throttle valve is connected in series in the main oil inlet of the system, and regulates the upward speed of the lifting cylinder by limiting the oil inlet flow; the relief valve connected in parallel in the oil circuit of the rod chamber of the lifting cylinder opens to overflow when the circuit pressure exceeds the set threshold, limiting the maximum pressure of the circuit and realizing overload protection;

[0059] S200, the lifting cylinder performs a descent action, and the manual directional valve switches to the downward working position; the pressure oil is output from the B port of the manual directional valve and sent to the control port of the hydraulic check valve to unlock the hydraulic check valve; the lifting cylinder is driven to descend by its own load gravity, and the oil discharged from the lifting cylinder flows back through the one-way throttle valve. The return flow area of ​​the one-way throttle valve is adjusted to control the descent speed of the lifting cylinder;

[0060] S300: When the lifting cylinder descends to its designated position and stops, the manual directional valve resets to its normal spring position, and the emergency stop valve remains in its original normal shut-off position, thus locking the lifting cylinder at its stop.

[0061] This invention abandons the traditional top-pressure operation method, driving the axial loading of the sample through the lifting and lowering of the lower-acting piston rod. This significantly expands the sample assembly and disassembly space, simplifies the clamping process, and improves testing efficiency. It is also suitable for testing large-size geological samples, overcoming the shortcomings of traditional equipment with limited loading range and the ability to test only small samples. Furthermore, it employs a dual-servo valve parallel redundant drive structure, which, compared to the traditional single-valve control method, effectively improves the hydraulic system's oil supply flow and loading response speed, and widens the loading rate adjustment range. This meets the requirements of high-precision, high-load, and high-speed rock axial loading tests. The dual-valve redundancy layout also effectively avoids test interruptions caused by single-valve failure, ensuring continuous and stable testing. Combined with the precise limiting structure of the worktable guide sleeve, it suppresses radial sway and offset of the piston rod, reducing mechanical motion errors. Combined with real-time closed-loop detection by a displacement sensor, it significantly improves the axial displacement control accuracy of the equipment.

[0062] Independent pore flow channels and confining pressure flow channels, with a rational layout and no interference between the two channels, overcome the technical shortcomings of traditional triaxial testing machines that are limited in function and unable to conduct pore pressure coupling tests. It can simultaneously complete ultra-high pressure confining loading and pore fluid injection tests on the sample, realistically simulating the stress state of rock masses under complex stress and pore fluid coupling environments in the formation, enriching test conditions and adapting to various geotechnical mechanics research and testing needs. Simultaneously, the sample adopts an assembly structure with an upper and lower end cap and a sealed rubber sleeve, and multiple strain test rings are arranged on the outside of the rubber sleeve, replacing the traditional manual single-point sensor pasting method. This enables multi-point synchronous acquisition of circumferential strain on the sample, avoiding the problems of cumbersome installation, poor consistency, and large data errors of traditional testing methods, comprehensively improving the accuracy and comprehensiveness of sample deformation detection. Attached Figure Description

[0063] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0064] Figure 2 This is a schematic diagram of the three-dimensional structure of the actuating cylinder;

[0065] Figure 3 This is a schematic diagram of the cross-sectional structure of the actuator cylinder;

[0066] Figure 4 This is the hydraulic schematic diagram of the actuator cylinder;

[0067] Figure 5 This is a schematic diagram of the three-dimensional structure of the sample mounting base;

[0068] Figure 6 This is a schematic diagram of the side structure of the sample mounting base;

[0069] Figure 7 This is a schematic diagram of the cross-sectional structure of the sample mounting base;

[0070] Figure 8 This is a schematic diagram of the three-dimensional structure of the sample mounting plate. Figure 1 ;

[0071] Figure 9 This is a schematic diagram of the three-dimensional structure of the sample mounting plate. Figure 2 ;

[0072] Figure 10 This is a schematic diagram of the three-dimensional structure of the sample assembly;

[0073] Figure 11 This is a schematic diagram of the cross-sectional structure of the sample assembly;

[0074] Figure 12 This is a schematic diagram of the cross-sectional structure of the high-pressure cylinder;

[0075] Figure 13 This is a schematic diagram of the three-dimensional structure of the lifting cylinder;

[0076] Figure 14 This is a schematic diagram of a pair of guide rails.

[0077] Figure 15 This is a schematic diagram of the three-dimensional structure of the lifting cylinder valve block. Figure 1 ;

[0078] Figure 16 This is a schematic diagram of the three-dimensional structure of the lifting cylinder valve block. Figure 2 ;

[0079] Figure 17 This is the hydraulic schematic diagram of the lifting cylinder valve;

[0080] Figure 18 This is a schematic diagram of the installation of test components in the experimental method;

[0081] Figure 19 This is a schematic diagram of the upward structure of the actuator cylinder in the test method;

[0082] Figure 20 This is a schematic diagram of the downward structure of the high-pressure cylinder in the test method;

[0083] Figure 21 This is a schematic diagram of the confining pressure test state structure in the test method;

[0084] Figure 22 This is a schematic diagram of the pore testing state structure in the experimental method;

[0085] In the diagram, 100 is the actuator assembly, 110 is the base, 120 is the actuator cylinder, 121 is the actuator piston rod, 1211 is the locating pin, 130 is the worktable, 131 is the guide sleeve, 140 is the actuator hydraulic servo module, 150 is the displacement sensor, and 160 is the crossbeam.

[0086] 200 is the sample mounting base, 210 is the mounting connection plate, 211 is the lower pore inlet, 220 is the sample mounting plate, 221 is the lower confining pressure inlet, 222 is the cylinder positioning pin, 223 is the pore outlet, 230 is the strain test transition plate, and 231 is the confining pressure outlet.

[0087] 300 is the sample assembly, 310 is the upper end cap, 320 is the rubber sleeve, 330 is the lower end cap, 340 is the sample, and 350 is the strain test ring.

[0088] 400 is the high-pressure cylinder, 410 is the high-pressure cylinder body, 411 is the confining pressure upper inlet, 412 is the dust cover, 413 is the leakage detection port, 420 is the high-pressure piston rod, 421 is the piston rod connecting plate, 4211 is the orifice upper inlet, and 430 is the force sensor.

[0089] 500 is the lifting cylinder, 510 is the upper mounting base, 520 is the stationary limit seat, and 530 is the cylinder connecting block.

[0090] 600 is the lifting cylinder valve block, 610 is the inlet throttle valve, 620 is the manual directional valve, 630 is the hydraulic check valve, 640 is the one-way throttle valve, 650 is the relief valve, and 660 is the emergency stop valve.

[0091] 700 refers to the guide rail. Detailed Implementation

[0092] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0093] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0094] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0095] The following is for reference. Figure 1-22 Describe embodiments of the present invention;

[0096] A type of down-moving triaxial testing machine for geological samples, such as Figure 1 As shown, it includes:

[0097] Actuator assembly 100 includes, from bottom to top, a base 110, an actuating cylinder 120, a worktable 130, an actuating hydraulic servo module 140, and a displacement sensor 150, which are fixedly connected in sequence; such as Figure 2-3 As shown,

[0098] The base 110 has a flat bottom surface and is fixedly connected to the bottom surface of the actuating cylinder 120.

[0099] The actuating cylinder 120 is equipped with an actuating piston rod 121, which reciprocates in the vertical direction.

[0100] The worktable 130 is fixedly mounted on the top of the actuating cylinder 120; a guide sleeve 131 is fixedly mounted in the middle of the worktable 130, and the top end of the actuating piston rod 121 extends outward from the guide sleeve 131 and slides and guides the guide sleeve 131.

[0101] The piston rod 121 of this invention has a positioning pin 1211 in the middle of the top surface. The positioning pin 1211 is fixedly connected to the receiving groove in the middle of the top surface of the piston rod 121 by thread. The top of the positioning pin 1211 extends out of the receiving groove and is adapted to the positioning hole at the bottom of the mounting plate 210.

[0102] The displacement sensor 150 is mounted on the actuating cylinder 120 to detect the extension displacement of the actuating piston rod 121 in real time.

[0103] Specifically, the displacement sensor 150 in this case is a magnetostrictive displacement sensor. The electronic compartment is fixedly installed at the bottom of the actuating cylinder 120. The probe extends into the inner cavity of the actuating cylinder 120 and is located inside the actuating piston rod 121. The sensor magnetic ring is fixedly installed at the bottom of the actuating piston rod 121. The probe extends into the sensor magnetic ring and is arranged along the axial direction of the actuating piston rod 121 to detect the extension displacement of the actuating piston rod 121 in real time.

[0104] The actuation hydraulic servo module 140, as shown Figure 4 As shown, the actuator includes a first servo valve and a second servo valve. The first control port of the first servo valve and the first control port of the second servo valve are respectively connected to the rodless chamber port of the actuator cylinder 120. The second control ports of the first servo valve and the second control ports of the second servo valve are respectively connected to the rod chamber port of the actuator cylinder 120. The signal output terminal of the displacement sensor 150 is connected to the displacement control unit, which is electrically connected to the control input terminals of the first servo valve and the second servo valve. The displacement control unit receives the displacement signal fed back from the displacement sensor, forms a closed-loop displacement control, and outputs a control signal to drive the first servo valve and / or the second servo valve to operate, thereby controlling the flow rate of hydraulic oil into and out of the two chambers of the actuator cylinder, and adjusting the movement position and speed of the actuated piston rod 121. Both the first servo valve and the second servo valve are equipped with a pressure port P and a return port T.

[0105] A sample mounting base 200 is disposed on the top surface of the actuating piston rod 121, and is raised and lowered by the actuating piston rod 121. The top surface of the sample mounting base 200 is provided with a sample mounting position for placing the sample assembly 300. The sample mounting base 200 is provided with a pore flow channel leading to the sample mounting position for pore testing of the sample assembly 300. The sample mounting base 200 is provided with a confining pressure flow channel leading to the side of the sample mounting position for confining pressure testing of the sample assembly 300.

[0106] Specifically, the sample mounting base 200 includes a mounting connection plate 210, a sample mounting plate 220, and a strain test transition plate 230 that are fixedly connected in sequence; wherein, the sample mounting plate 220 and the mounting connection plate 210 are positioned by multiple connecting plate positioning pins and then fastened together by screws.

[0107] The mounting plate 210 has a lower inlet 211 on its side; the top surface of the sample mounting plate 220 has a pore outlet 223 adapted to the sample assembly 300. The pore outlet 223 is connected to the lower inlet 211 and is used to allow fluids such as ultra-high pressure water to enter the pores of the sample 340 during pore testing.

[0108] Further optimization involves providing an annular groove on the top surface of the sample mounting plate 220, with the pore outlet 223 located on the annular groove. The fluid flowing out of the pore outlet 223 is located in the annular groove, and then the fluid enters the sample 340. Thus, the sample 340 only needs to be placed on the annular groove, without the need for the pore outlet 223 to correspond with the hole on the sample assembly 300, further improving placement efficiency and test stability.

[0109] The sample mounting plate 220 is provided with a confining pressure inlet 221 on its side, and the strain test transition plate 230 is provided with a confining pressure outlet 231 that communicates with the confining pressure inlet 221. The confining pressure outlet 231 is located on the side of the sample mounting position and is used to allow ultra-high pressure hydraulic oil to enter around the sample assembly 300 during the confining pressure test.

[0110] Further optimization, such as Figure 5 , 8 As shown in Figure 9, the strain test transition plate 230 has a ring-shaped structure and is sealed and fixedly sleeved in the middle of the sample mounting plate 220. Its top surface is provided with multiple electrical connection terminals located on the side of the sample mounting position. The bottom of the sample mounting plate 220 is provided with multiple wire grooves. One end of the corresponding test wire is connected to the electrical connection terminal, and the other end passes through the corresponding through hole of the strain test transition plate 230 into the wire groove and out to connect with external equipment.

[0111] Sample assembly 300, such as Figure 10-11 As shown;

[0112] The sample assembly 300 is set on the sample mounting position and includes an upper end cover 310, a rubber sleeve 320 and a lower end cover 330. Whether the lower end cover 330 needs to be fixedly installed with the strain test transition plate 230 depends on the compatibility selection based on the sample diameter and test requirements. If fixing is required, a threaded hole can be added to the corresponding position on the lower end cover 330, and the bottom of the lower end cover 330 is provided with an external thread that matches the threaded hole.

[0113] The sample 340 is disposed between the upper end cap 310 and the lower end cap 330; the upper end cap 310 and the lower end cap 330 are respectively provided with fluid through holes to allow fluid to enter the interior of the sample 340; the rubber sleeve 320 is wrapped around the sample 340; a plurality of strain test rings 350 are provided on the outside of the rubber sleeve 320.

[0114] Specifically, the upper end cap 310 is connected and fixed to the sample 340 and the lower end cap 330 is connected and fixed to the sample 340 by tape. After fixing, the sample 340 is wrapped by a rubber sleeve 320 to isolate it from the outside. The porosity test is only performed through the fluid passage holes on the upper end cap 310 and the lower end cap 330.

[0115] The structure of the high-pressure cylinder 400 is as follows: Figure 12 As shown;

[0116] The high-pressure cylinder 400 includes a high-pressure cylinder body 410, a high-pressure piston rod 420, and a force sensor 430.

[0117] The force sensor 430 is fixedly mounted on the bottom of the high-pressure piston rod 420;

[0118] The top of the high-pressure piston rod 420 is fixedly connected to the crossbeam 160 via the piston rod connecting plate 421; the piston rod connecting plate 421 is provided with an upper inlet 4211; the upper inlet 4211 passes through the piston rod connecting plate 421, the high-pressure piston rod 420 and the drainage hole on the force sensor 430 in sequence, so that liquids such as ultra-high pressure water used for porosity testing can enter the sample 340 through the drainage hole;

[0119] The high-pressure cylinder 410 reciprocates up and down below the crossbeam 160 via a vertically arranged lifting cylinder 500 along the axial direction of the high-pressure piston rod 420; the side of the high-pressure cylinder 410 is provided with a confining pressure upper inlet 411; the ultra-high pressure hydraulic oil used for the confining pressure test flows into the high-pressure cylinder 410 through the confining pressure upper inlet 411, thereby entering the surrounding area of ​​the sample assembly.

[0120] The top surface of the sample mounting plate 220 near the edge is provided with multiple fixed cylinder positioning pins 222. The top section of the cylinder positioning pin 222 is tapered, used for alignment when the high-pressure cylinder 400 descends onto the sample mounting plate 220. The bottom of the high-pressure cylinder body 410 is provided with multiple pin holes corresponding to the cylinder positioning pins 222. When the high-pressure cylinder body 410 descends, the pin holes are positioned by the corresponding cylinder positioning pins 222. The connection between the high-pressure cylinder body 410 and the high-pressure piston rod 420 is sealed at the top by multiple ultra-high pressure seals adapted to its pressure.

[0121] To further improve the dustproof effect between the top of the high-pressure cylinder 410 and the high-pressure piston rod 420, a fixed dustproof cover 412 is provided on the top of the high-pressure cylinder 410. The dustproof cover 412 is sleeved on the high-pressure piston rod 420, and dustproof rings are used to prevent dust between the dustproof cover 412 and the outer surface of the high-pressure piston rod 420.

[0122] Further improve the ease of placing large-diameter samples:

[0123] The worktable 130 is equipped with a pair of fixed guide rails 700;

[0124] The slider on the guide rail 700 is fixedly connected to the side of the mounting connecting plate 210. The mounting connecting plate 210 is slid out of the worktable 130 via a pair of guide rails 700, facilitating the installation of larger sample assemblies 300. Figure 1 , 14 As shown.

[0125] The lifting cylinder 500 in this case includes an electric lifting cylinder, a pneumatic lifting cylinder, or a hydraulic lifting cylinder; the cylinder body of the lifting cylinder 500 is fixedly connected to the crossbeam 160, and the piston rod end is fixedly connected to the high-pressure cylinder body 410.

[0126] This case favors a hydraulic lifting cylinder:

[0127] Specifically, such as Figure 13 As shown, the cylinder body of the lifting cylinder 500 is fixedly mounted on the side of the crossbeam 160 via the upper mounting seat 510 and the stationary limit seat 520, and the piston rod end is fixedly connected to the high pressure cylinder body 410 via the fixedly connected cylinder connecting block 530.

[0128] The side of the stationary limiting seat 520 is provided with a first insertion hole;

[0129] The cylinder connecting block 530 has a second insertion hole on its side that matches the first insertion hole; after the first insertion hole and the second insertion hole are aligned, the cylinder connecting block 530 is fixed to the stationary limiting seat 520 by a pin. In this invention, the lifting cylinder 500 piston rod rises or falls to achieve the lifting or lowering of the high-pressure cylinder body 410. After the high-pressure cylinder body 410 is lifted into position, the limiting hole on the cylinder connecting block 530 is aligned with the hole on the stationary limiting seat 520 and fixed with a pin; when lowering, the pin must be removed before it can fall.

[0130] The lifting cylinder 500 is connected to the lifting cylinder valve block 600, which controls the raising or lowering of the high-pressure cylinder body 410. Figure 15-17 As shown;

[0131] The lifting cylinder valve block 600 integrates an inlet throttle valve 610, a manual directional valve 620, a hydraulic check valve 630, a one-way throttle valve 640, an overflow valve 650, and an emergency stop valve 660.

[0132] The oil inlet of the inlet throttle valve 610 is connected to the oil inlet P of the lifting cylinder valve block 600, and the oil outlet is connected to the main oil supply channel of the manual reversing valve 620.

[0133] The manual directional valve 620 has a main oil supply port and a hydraulic control oil supply port at its outlet end. The main oil supply port is connected to the main oil inlet of the hydraulic control check valve 630, and the hydraulic control oil supply port is connected to the control oil port of the hydraulic control check valve 630.

[0134] The oil outlet of the hydraulic control check valve 630 is connected to the oil inlet of the one-way throttle valve 640.

[0135] The overflow valve 650 and the emergency stop valve 660 are connected in parallel, and the two ends of the parallel branch are respectively connected to the oil outlet of the one-way throttle valve 640 and the oil return passage.

[0136] The oil outlet of the one-way throttle valve 640 and the oil inlet of the overflow valve 650 are connected to the rod chamber of the lifting cylinder.

[0137] The relief valve 650 is connected in parallel to the load oil circuit of the lifting cylinder 500 to achieve system pressure limiting; the emergency stop valve 660 can quickly unload and cut off the load pressure.

[0138] Before the lifting cylinder performs its upward movement, the emergency stop valve 660 must be switched to the right position to open the oil supply passage of the rod chamber of the lifting cylinder 500; then the manual directional valve 620 is pulled to the left position, and the system pressure oil is output to the rod chamber of the lifting cylinder 500 through the inlet throttle valve 610 and the manual directional valve 620A port, driving the lifting cylinder 500 to move upward.

[0139] When the lifting cylinder 500 descends, the manual directional valve 620 is in the right position: at this time, the pressure oil is output from port B of the manual directional valve 620 and enters the control port of the hydraulic check valve 630 to unlock the hydraulic check valve 630; the lifting cylinder 500 is driven to descend by its own load gravity, and the oil in the cylinder flows back through the one-way throttle valve 640. The one-way throttle valve 640 adjusts the return oil flow area to achieve controllable descent speed.

[0140] When the lifting cylinder 500 stops at the end position of the descent, the manual reversing valve 620 remains in the right position with the spring reset, and the emergency stop valve is in the normal left position.

[0141] The imported throttle valve 610 is connected in series in the main oil inlet of the system to regulate the upward speed of the lifting cylinder by limiting the oil inlet flow; the relief valve 650 is connected in parallel in the rod chamber oil circuit of the lifting cylinder 500. When the system pressure exceeds the limit, it automatically overflows to relieve pressure, limits the maximum pressure of the circuit, and provides overload protection for the lifting cylinder 500 and valve block components.

[0142] This design utilizes a lifting cylinder 500 to drive the high-pressure cylinder 410 in axial reciprocating motion, eliminating the need to move the heavy-duty crossbeam 160 to complete the opening and closing clamping of the sample 340. This significantly reduces the equipment's drive load and operating energy consumption, and the structural design better suits actual experimental operation requirements. The high-pressure piston rod 420 integrates a force sensor 430 at its bottom, featuring a short force detection path and minimal mechanical interference. This allows for direct and accurate acquisition of the axial loading pressure data of the sample 340. Combined with the precise liquid guiding structure of the top pore inlet 4211 and the confining pressure inlet 411, this ensures the smooth and orderly conduct of pore pressure tests and ultra-high pressure confining pressure tests, further enhancing the overall operational stability and experimental reliability of the equipment.

[0143] A test method for a downward-moving triaxial testing machine for geological samples, comprising the following steps:

[0144] Step 1, as follows Figure 18 As shown, the drive lifting cylinder 500 is activated to lift the high-pressure cylinder 400 to the highest point of its stroke; the cylinder connecting block 530 is rigidly locked to the stationary limit seat 520, and the force sensor 430 is assembled to the lower end of the high-pressure piston rod 420;

[0145] Step 2: Insert the test sample component 300 into the sample mounting position of the sample mounting base 200;

[0146] Step 3: Complete the electrical connection between the strain test ring 350, the force sensor 430, and the strain test transition plate 230;

[0147] Step four: The actuating piston rod 121 of the actuating cylinder 120 moves upward until the upper end cover 310 of the sample assembly 300 is in contact with the force sensor 430. When the feedback load of the force sensor 430 reaches 1% of the rated working range (for example, the rated pressure is 1000kN and the feedback pressure reaches 10kN), the actuating piston rod 121 stops feeding. Figure 19 As shown;

[0148] Step 5: Release the rigid lock between the cylinder connecting block 530 and the stationary limit seat 520, drive the lifting cylinder 500 downward, causing the lower end of the high-pressure cylinder body 410 to close with the sample mounting plate 220, forming a sealed pressure chamber. Figure 20 As shown; the high-pressure cylinder body 410 and the sample mounting plate 220 are fastened together by a connector and sealed by a sealing ring;

[0149] After the high-pressure cylinder 410 is pressed down to the position, the high-pressure cylinder 410's confining inlet 411 is connected to the confining inlet 221 of the sample mounting plate 220 through the inner cavity of the high-pressure cylinder 410.

[0150] The piston rod connecting plate 421 is provided with an upper inlet 4211. The upper inlet 4211 is connected to the lower inlet 211 via the drain holes on the piston rod connecting plate 421, the high-pressure piston rod 420 and the force sensor 430 in sequence. All components are sealed by ultra-high pressure seals.

[0151] The high-pressure cylinder body 410 and the sample mounting base 200 can be further locked together by a connector;

[0152] Step 6, confining pressure test, such as Figure 21 As shown;

[0153] High-pressure hydraulic oil is introduced into the sealed cavity of the high-pressure cylinder 410 through the upper confining pressure inlet 411 and the lower confining pressure inlet 221 to establish the confining pressure environment around the sample; the emergency stop valve 660 is switched to the right-hand position, and the manual directional valve 620 is kept in the reset right position.

[0154] By gradually increasing the loading pressure of the actuating piston rod 121, the load signal of the force sensor 430 and the deformation data of the strain test ring 350 under the corresponding loading pressure are collected to obtain the pressure stress performance parameters of the sample; the reserved leakage detection hole 413 in this case is equipped with a pressure sensor or pressure gauge, and the sealing status of the cavity is monitored in real time through the reserved leakage detection hole 413 near the top of the high pressure cylinder 410.

[0155] Step 7, porosity testing, such as Figure 22 As shown;

[0156] Throughout the porosity test, a certain pressure of confining hydraulic oil is maintained on the outside of the sample to prevent damage to the outer sealing sleeve of the sample due to pressure difference.

[0157] High-pressure water or other test fluids are introduced through the upper inlet 4211 and the lower inlet 211 of the pore, and enter the upper and lower ends of the sample.

[0158] Gradually increase the loading pressure of the actuating piston rod 121, and simultaneously collect the load signal of the force sensor 430 and the deformation data of the strain test ring 350 to detect the stress bearing capacity of the sample under the coupled conditions of pore fluid and confining pressure.

[0159] Step 8: After all tests are completed, first completely depressurize the hydraulic pressure in the high-pressure cylinder 410 chamber to zero. After confirming that there is no residual high pressure, drive the lifting cylinder 500 to lift the high-pressure cylinder and reset it.

[0160] In summary, the present invention has a scientific and reasonable structural layout, taking into account the ease of operation, loading stability and testing accuracy. It can efficiently complete a variety of tests such as axial pressure test, ultra-high pressure confining pressure test, pore pressure test and circumferential strain detection of large-size geological samples, accurately simulate the stress environment of complex rock strata, and has strong adaptability to geotechnical research and engineering promotion value.

[0161] Regarding the information disclosed in this case, the following points need to be clarified:

[0162] (1) The accompanying drawings of the embodiments disclosed in this case only involve the structures involved in the embodiments disclosed in this case. Other structures can refer to the general design.

[0163] (2) Where there is no conflict, the embodiments and features disclosed in this case can be combined with each other to obtain new embodiments;

[0164] The above are merely specific embodiments disclosed in this case, but the scope of protection of this disclosure is not limited thereto. The scope of protection disclosed in this case shall be determined by the scope of protection of the claims.

Claims

1. A downward-moving triaxial testing machine for geological samples, characterized in that, include: The actuator assembly (100) includes an actuator cylinder (120), a worktable (130), an actuation hydraulic servo module (140), and a displacement sensor (150) that are fixedly connected from bottom to top. The actuating cylinder (120) is equipped with an actuating piston rod (121) that reciprocates in the vertical direction. The worktable (130) is fixedly installed on the top of the actuating cylinder (120); a guide sleeve (131) is fixedly installed in the middle of the worktable (130), and the top end of the actuating piston rod (121) extends outward from the inside of the guide sleeve (131) and slides and guides the guide sleeve (131). The displacement sensor (150) is installed on the actuating cylinder (120) to detect the extension displacement of the actuating piston rod (121) in real time; The actuation hydraulic servo module (140) includes a first servo valve and a second servo valve; the first control port of the first servo valve and the first control port of the second servo valve are respectively connected to the rodless chamber port of the actuation cylinder (120); the second control port of the first servo valve and the second control port of the second servo valve are respectively connected to the rod chamber port of the actuation cylinder (120); the signal output terminal of the displacement sensor (150) is connected to the displacement control unit, and the displacement control unit is electrically connected to the control input terminals of the first servo valve and the second servo valve respectively to adjust the movement position and movement speed of the actuation piston rod (121); A sample mounting base (200) is disposed on the top surface of the actuating piston rod (121) and is raised and lowered by the actuating piston rod (121). The top surface of the sample mounting base (200) is provided with a sample mounting position for placing the sample assembly (300). The sample mounting base (200) is provided with a pore flow channel leading to the sample mounting position for pore testing of the sample assembly (300). The sample mounting base (200) is provided with a confining pressure flow channel leading to the side of the sample mounting position for confining pressure testing of the sample assembly (300). The sample assembly (300) is disposed on the sample mounting position and includes an upper end cap (310), a rubber sleeve (320) and a lower end cap (330). The sample (340) is disposed between the upper end cap (310) and the lower end cap (330); the upper end cap (310) and the lower end cap (330) are respectively provided with fluid through holes to allow fluid to enter the interior of the sample (340); the rubber sleeve (320) is wrapped around the sample (340); the rubber sleeve (320) is provided with multiple strain test rings (350) on the outside. The high-pressure cylinder (400) includes a high-pressure cylinder body (410), a high-pressure piston rod (420), and a force sensor (430). The force sensor (430) is fixedly mounted on the bottom of the high-pressure piston rod (420); The top of the high-pressure piston rod (420) is fixedly connected to the crossbeam (160) through the piston rod connecting plate (421); the piston rod connecting plate (421) is provided with an upper inlet (4211); the upper inlet (4211) passes through the piston rod connecting plate (421), the high-pressure piston rod (420) and the drainage hole on the force sensor (430) in sequence, so that when the pore test is used, the liquid enters the end face of the sample (340) through the drainage hole; The high-pressure cylinder (410) moves up and down below the crossbeam (160) via the lifting cylinder (500) along the axial direction of the high-pressure piston rod (420); the side of the high-pressure cylinder (410) is provided with a confining pressure upper inlet (411); the ultra-high pressure hydraulic oil used for the confining pressure test flows into the high-pressure cylinder (410) through the confining pressure upper inlet (411), thereby entering the surrounding area of ​​the sample assembly.

2. The triaxial testing machine for downward-moving geological samples according to claim 1, characterized in that, The workbench (130) is provided with a pair of fixed guide rails (700); The slider on the guide rail (700) is fixedly connected to the side of the mounting connection plate (210) in the sample mounting base (200). The mounting connection plate (210) is slid out from the worktable (130) by a pair of guide rails (700) to facilitate the installation of the sample assembly (300).

3. The triaxial testing machine for downward-moving geological samples according to claim 1, characterized in that, The lifting cylinder (500) includes an electric lifting cylinder, a pneumatic lifting cylinder, or a hydraulic lifting cylinder; The cylinder body of the lifting cylinder (500) is fixedly connected to the crossbeam (160), and the piston rod end is fixedly connected to the high-pressure cylinder body (410).

4. The triaxial testing machine for downward-moving geological samples according to claim 3, characterized in that, The cylinder body of the lifting cylinder (500) is fixedly mounted on the side of the crossbeam (160) via an upper mounting seat (510) and a stationary limiting seat (520), and the piston rod end is fixedly connected to the high-pressure cylinder body (410) via a fixedly connected cylinder connecting block (530). The side of the stationary limiting seat (520) is provided with a first insertion hole; The cylinder connecting block (530) has a second socket on its side that is adapted to the first socket; after the first socket and the second socket are aligned, the cylinder connecting block (530) is fixed to the stationary limiting seat (520) by a pin.

5. The triaxial testing machine for downward-moving geological samples according to claim 1, characterized in that, The lifting cylinder (500) is connected to the lifting cylinder valve block (600), and the lifting cylinder valve block (600) controls the rise or fall of the high-pressure cylinder body (410); The lifting cylinder valve block (600) is equipped with an inlet throttle valve (610), a manual reversing valve (620), a hydraulic check valve (630), a one-way throttle valve (640), an overflow valve (650), and an emergency stop valve (660). The inlet end of the inlet throttle valve (610) is connected to the inlet port P of the lifting cylinder valve block (600), and the outlet end is connected to the main oil supply channel of the manual reversing valve (620). The manual directional valve (620) is provided with a main oil supply port and a hydraulic control oil supply port at its outlet end. The main oil supply port is connected to the main oil inlet of the hydraulic control check valve (630), and the hydraulic control oil supply port is connected to the control oil port of the hydraulic control check valve (630). The oil outlet of the hydraulic control check valve (630) is connected to the oil inlet of the check valve (640); The overflow valve (650) and the emergency stop valve (660) are connected in parallel, and the two ends of the parallel branch are respectively connected to the oil outlet of the one-way throttle valve (640) and the oil return passage. The oil outlet of the one-way throttle valve (640) and the oil inlet of the overflow valve (650) are connected to the rod chamber of the lifting cylinder.

6. The triaxial testing machine for downward-moving geological samples according to claim 1, characterized in that, The displacement sensor (150) is a magnetostrictive displacement sensor. Its electronic compartment is fixedly installed at the bottom of the actuating cylinder (120). The probe extends into the inner cavity of the actuating cylinder (120) and is located inside the actuating piston rod (121) to detect the extension displacement of the actuating piston rod (121) in real time.

7. The triaxial testing machine for downward-moving geological samples according to claim 1, characterized in that, The sample mounting base (200) includes a mounting connection plate (210), a sample mounting plate (220), and a strain test transition plate (230) that are fixedly connected in sequence. The mounting plate (210) has a pore inlet (211) on its side; the top surface of the sample mounting plate (220) has a pore outlet (223) adapted to the sample assembly (300), and the pore outlet (223) is connected to the pore inlet (211) so that fluid can enter the pores of the sample (340) during pore testing.

8. A downward-moving triaxial testing machine for geological samples according to claim 7, characterized in that, The sample mounting plate (220) is provided with a confining pressure inlet (221) on its side, and the strain test transition plate (230) is provided with a confining pressure outlet (231) that communicates with the confining pressure inlet (221). The confining pressure outlet (231) is located on the side of the sample mounting position and is used to allow hydraulic oil to enter around the sample assembly (300) during the confining pressure test.

9. A test method for a downward-moving triaxial testing machine for geological samples, using the downward-moving triaxial testing machine for geological samples as described in claim 1, characterized in that, The steps are as follows: Step 1: Drive the lifting cylinder (500) to lift the high-pressure cylinder (400) to the highest point of its stroke; the cylinder connecting block (530) is rigidly locked to the stationary limit seat (520), and the force sensor (430) is assembled to the lower end of the high-pressure piston rod (420); Step 2: Insert the sample component (300) to be tested into the sample mounting position of the sample mounting base (200); Step 3: Complete the signal electrical connection of the strain test ring (350) and the force sensor (430); Step 4: The actuating piston rod (121) of the actuating cylinder (120) moves upward until the upper end cover (310) of the sample assembly (300) is in contact with the force sensor (430). When the load fed back by the force sensor (430) reaches 1% of the rated working range, the actuating piston rod (121) stops feeding. Step 5: Release the rigid lock between the cylinder connecting block (530) and the stationary limit seat (520), drive the lifting cylinder (500) to move downward, and drive the lower end of the high pressure cylinder body (410) to close with the sample mounting plate (220) to form a closed pressure chamber; After the high-pressure cylinder (410) is pressed down to the position, the upper inlet (411) of the high-pressure cylinder (410) is connected to the lower inlet (221) of the sample mounting plate (220) through the inner cavity of the high-pressure cylinder (410); The piston rod connecting plate (421) is provided with an upper inlet (4211), which passes through the piston rod connecting plate (421), the high pressure piston rod (420) and the drainage hole on the force sensor (430) in sequence, and is connected to the lower inlet (211). Step 6, Confining pressure test High-pressure hydraulic oil is introduced into the sealed cavity of the high-pressure cylinder (410) through the upper confining pressure inlet (411) and the lower confining pressure inlet (221) to establish the confining pressure environment around the sample; the emergency stop valve (660) is switched to the right-hand position, and the manual directional valve (620) is kept in the reset right-hand position; By gradually increasing the loading pressure of the actuating piston rod (121), the load signal of the force sensor (430) and the deformation data of the strain test ring (350) under the corresponding loading pressure are collected to obtain the compressive stress performance parameters of the sample. Step 7, Porosity Testing Confining hydraulic oil maintaining a certain pressure on the outside of the sample; Test fluid is introduced into the upper and lower ends of the sample through the upper inlet (4211) and the lower inlet (211) of the pore; the loading pressure of the actuating piston rod (121) is gradually increased, and the load signal of the force sensor (430) and the deformation data of the strain test ring (350) are collected simultaneously to detect the stress bearing capacity of the sample under the coupled conditions of pore fluid and confining pressure. Step 8: After all tests are completed, first completely depressurize the hydraulic pressure in the high-pressure cylinder (410) cavity to zero. After confirming that there is no residual high pressure, drive the lifting cylinder (500) to lift the high-pressure cylinder and reset it.

10. The test method of a downward-moving triaxial testing machine for geological samples according to claim 9, characterized in that, The control method for the lifting cylinder (500) includes: S100, the lifting cylinder (500) performs an upward movement, the emergency stop valve (660) switches to the working conduction position, and the oil supply passage of the rod chamber of the lifting cylinder (500) is opened; then the manual reversing valve (620) is switched to the upward working position, and the system pressure oil is delivered to the rod chamber of the lifting cylinder (500) through the inlet throttle valve (610) and the A oil port of the manual reversing valve (620) in sequence, driving the lifting cylinder (500) to move upward; among them, the inlet throttle valve (610) is connected in series in the main oil inlet of the system, and the upward speed of the lifting cylinder (500) is adjusted by limiting the oil inlet flow; the overflow valve (650) connected in parallel in the oil circuit of the rod chamber of the lifting cylinder (500) opens the overflow when the circuit pressure exceeds the set threshold, limiting the maximum pressure of the circuit and realizing overload protection; S200, the lifting cylinder (500) performs a descent action, and the manual directional valve (620) switches to the downward working position; the pressure oil is output from the B port of the manual directional valve (620) and delivered to the control port of the hydraulic control check valve (630) to unlock the hydraulic control check valve (630); the lifting cylinder (500) is driven to descend by its own load gravity, and the oil discharged from the lifting cylinder (500) flows through the one-way throttle valve (640) to return oil. The return oil flow area of ​​the one-way throttle valve (640) is adjusted to control the descent speed of the lifting cylinder (500); S300, the lifting cylinder (500) descends to its position and stops, the manual directional valve (620) resets to the spring normal position, and the emergency stop valve (660) remains in its original normal stop position, thus stopping and locking the lifting cylinder (500).

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