A confining pressure rating test device and test method

Abstract

The present invention discloses a confining pressure calibration test device and a test method, the test device comprises a confining pressure calibration cabin, a lifting component and a rubber sleeve component, the confining pressure calibration cabin is a hollow structure, a pressure chamber is arranged in the confining pressure calibration cabin, the rubber sleeve component and the pressure chamber are coaxially arranged, and the outer wall of the rubber sleeve component is connected with the pressure chamber, the cylindrical core is a cylindrical core with a strain gauge, and the lifting component comprises a circular ring positioning plate installed in the pressure chamber, and the circular ring positioning plate is lifted and lowered along the height direction of the rubber sleeve component; the test method comprises the following steps: 1. Adjustment of the lifting component; 2. Installation of the cylindrical core and the plunger rod; 3. Confining pressure test; 4. Mechanical parameter processing of the cylindrical core. The present invention is reasonably designed and low in cost, and effectively adapts to cylindrical cores of different lengths, so as to facilitate the subsequent analysis of the influence of the mechanical parameters of the cylindrical core under different height-to-diameter ratios.

Description

Technical Field

[0001] The invention belongs to the technical field of confining pressure calibration instruments for tunnel geostress testing, and in particular relates to a confining pressure calibration test device and a test method. Background Art

[0002] In-situ stress measurement is an important part of the evaluation of rock mass stability and the design of support structures for underground engineering. Among them, in-situ stress measurement using hollow inclusion strain gauges is widely used because of its advantages of easy use, simple installation, high efficiency and low cost. In the process of hollow inclusion strain gauge measurement test, confining pressure calibration is an important supporting test, which is used to indirectly obtain the mechanical parameters of the core, so as to facilitate the further derivation of the in-situ stress. For the surrounding rock with good integrity in the tunnel detection area, a cylindrical core of ideal length can generally be obtained to carry out the confining pressure calibration test. However, for the surrounding rock with relatively developed bedding, joints and fissures in the tunnel detection area, the length of the cylindrical core taken during the stress relief of the hollow inclusion is insufficient, and it is difficult to cover the pressurization range of the rubber sleeve of the calibration instrument, so the confining pressure calibration test cannot be carried out. To this end, it is necessary to break through the limitations of conventional confining pressure calibration instruments and develop a method for measuring the mechanical parameters of cylindrical cores according to the length of the cylindrical cores taken. In addition, it is convenient to analyze the influence of the mechanical parameters of cylindrical cores under different height-to-diameter ratios, improve the utilization rate of cylindrical core samples and the accuracy of the measured data.

[0003] At present, there are relatively few studies on confining pressure calibration instruments for hollow inclusion ground stress measurement at home and abroad. For example, the multi-caliber general high-pressure confining pressure calibration instrument can simulate the high ground stress environment of deep rock mass and obtain relevant deformation parameters, but it does not consider the deformation parameter testing of cores with different height-to-diameter ratios. Therefore, in order to obtain the mechanical parameters of cores with different height-to-diameter ratios and simulate the influence of size effect on rock mass deformation parameters, it is necessary to develop an adjustable confining pressure calibration test device and test method. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a confining pressure calibration test device in view of the deficiencies in the above-mentioned prior art, which has a reasonable design and low cost, and can effectively adapt to cylindrical rock cores of different lengths, thereby facilitating the subsequent analysis of the influence of the mechanical parameters of the cylindrical rock cores under different aspect ratios.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a confining pressure calibration test device, characterized in that it includes a confining pressure calibration cabin, a lifting component arranged in the confining pressure calibration cabin, and a rubber sleeve component arranged at the center of the confining pressure calibration cabin and for the cylindrical rock core to be installed, the confining pressure calibration cabin is a hollow structure, a pressure chamber is arranged in the confining pressure calibration cabin, the rubber sleeve component and the pressure chamber are coaxially arranged, and the outer side wall of the rubber sleeve component is connected to the pressure chamber, and the cylindrical rock core is a cylindrical rock core with a strain gauge;

[0006] The lifting component comprises a circular ring positioning plate installed in the pressure chamber, the circular ring positioning plate is sleeved outside the rubber sleeve component, and the circular ring positioning plate is lifted and lowered along the height direction of the rubber sleeve component.

[0007] The above-mentioned confining pressure calibration test device is characterized in that: the annular positioning plate is provided with an adjusting rod, the number of the adjusting rods is multiple, and the multiple adjusting rods are evenly distributed along the circumferential direction of the edge of the annular positioning plate;

[0008] A lower nut is provided on the top of the confining pressure rate cabin body, an adjusting nut is provided on the lower nut, the top end of the adjusting rod passes through the pressure chamber, the lower nut and the adjusting nut in sequence, the top end of the adjusting rod extends out of the adjusting nut, and the adjusting nut and the adjusting rod are threadedly connected.

[0009] The above-mentioned confining pressure rating test device is characterized in that: the confining pressure rating cabin comprises a bottom plate, a top plate and an intermediate cabin arranged between the bottom plate and the top plate, the intermediate cabin is a hollow structure, and the center positions of the bottom plate and the top plate are respectively provided with center through holes for installing the rubber sleeve component;

[0010] The pressure chamber is surrounded by an intermediate cabin body and an outer side wall of the rubber sleeve component, and an oil filling pipe communicating with the pressure chamber is arranged on the intermediate cabin body.

[0011] The above-mentioned confining pressure calibration test device is characterized in that: a lower bottom plate is provided at the bottom of the intermediate cabin, an upper top plate is provided at the top of the intermediate cabin, the upper top plate and the top plate are detachably connected, and the lower bottom plate and the bottom plate are detachably connected.

[0012] The above-mentioned confining pressure calibration test device is characterized in that: locking screws are arranged in the upper top plate, the top plate, the lower bottom plate and the bottom plate of the intermediate cabin, the number of the locking screws is multiple, and the multiple locking screws are evenly distributed along the circumferential direction of the outer side wall of the intermediate cabin, and the bottom of the locking screw is flush with the bottom of the bottom plate;

[0013] The outer side wall of the intermediate cabin is provided with an arc-shaped groove for the locking screw to be embedded in, and the distance between the bottom of the arc-shaped groove and the outer side wall of the intermediate cabin is smaller than the diameter of the locking screw.

[0014] The above-mentioned confining pressure calibration test device is characterized in that a plunger rod is inserted into the rubber sleeve component, and the outer side wall of the plunger rod is in contact with the inner side wall of the rubber sleeve component.

[0015] The above-mentioned confining pressure calibration test device is characterized in that: the rubber sleeve component includes a rubber sleeve, the bottom end of the rubber sleeve is flush with the bottom surface of the bottom plate in the confining pressure calibration cabin, the top end of the rubber sleeve is flush with the top surface of the top plate in the confining pressure calibration cabin, and the outer side wall of the rubber sleeve is connected to the pressure chamber.

[0016] The above-mentioned confining pressure calibration test device is characterized in that: a lower connecting plate is provided at the lower part of the rubber sleeve, an upper connecting plate is provided at the upper part of the rubber sleeve, and both the lower connecting plate and the upper connecting plate are circular ring plates;

[0017] The lower connecting plate is located between the bottom of the middle cabin and the bottom plate, and the upper connecting plate is located between the top of the middle cabin and the top plate.

[0018] The above-mentioned confining pressure calibration test device is characterized in that: a lower sealing ring is arranged between the bottom of the intermediate cabin and the bottom plate, an upper sealing ring is arranged between the top of the intermediate cabin and the top plate, the inner side wall of the lower sealing ring is in contact with the outer side wall of the lower connecting plate, and the inner side wall of the upper sealing ring is in contact with the outer side wall of the upper connecting plate.

[0019] At the same time, the present invention also discloses a confining pressure calibration test method with simple steps, reasonable design and convenient implementation, characterized in that the method comprises the following steps:

[0020] Step 1: Adjustment of lifting components:

[0021] Step 101, placing a cylindrical support at the bottom of the rubber sleeve in the rubber sleeve component;

[0022] Step 102: according to the height L of the cylindrical core, adjust the circular ring positioning plate to rise and fall along the height direction of the rubber sleeve until the distance between the bottom of the circular ring positioning plate and the top of the cylindrical support is equal to the height L of the cylindrical core; wherein the height L of the cylindrical core is less than the height of the rubber sleeve;

[0023] Step 2: Installation of cylindrical core and plunger rod:

[0024] Step 201, placing a cylindrical rock core in a rubber sleeve; wherein the bottom of the cylindrical rock core is fitted with the top of the cylindrical support, the cylindrical rock core is obtained by sending a hollow inclusion strain gauge into a tunnel detection area by using a casing stress relief method, and the cross section of the cylindrical rock core is a circular ring;

[0025] Step 202, inserting a plunger rod into the rubber sleeve until the bottom of the plunger rod fits with the top of the cylindrical rock core; wherein the outer wall of the plunger rod fits with the inner wall of the rubber sleeve;

[0026] Step 3: Confining pressure test:

[0027] Step 301, connecting the oil injection pipe on the confining pressure rate constant cabin to the oil injection pump;

[0028] Step 302, operate the oil injection pump to inject hydraulic oil into the pressure chamber through the oil injection pipe until the pressure in the pressure chamber reaches 1 MPa, and perform the first confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber in the first confining pressure calibration test on the cylindrical rock core is recorded as the first confining pressure value P1;

[0029] Step 303, repeating step 302 until the pressure in the pressure chamber reaches 2 MPa, and performing a second confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber during the second confining pressure calibration test on the cylindrical rock core is recorded as the second confining pressure value P2;

[0030] Step 304: Repeat step 303 multiple times to obtain the i-th confining pressure value P i and the i+1th confining pressure value P i+1 ; Among them, P i+1 -P i =1MPa;

[0031] Step 305: Repeat step 304 n times to obtain the nth confining pressure value P n ; Wherein, i and n are both positive integers, n≥5, 1≤i≤n;

[0032] Step 4: Mechanical parameter processing of cylindrical core:

[0033] Step 401: a first group of strain gauges, a second group of strain gauges and a third group of strain gauges are arranged in the cylindrical rock core, the first group of strain gauges, the second group of strain gauges and the third group of strain gauges are evenly distributed along the circumferential direction of the cylindrical rock core, and the first group of strain gauges, the second group of strain gauges and the third group of strain gauges each include two strain gauges, the two strain gauges are respectively a first strain gauge and a second strain gauge, the first strain gauge and the axis of the cylindrical rock core are at an angle of 90°, and the second strain gauge and the axis of the cylindrical rock core are parallel;

[0034] Step 402: During the i-th confining pressure calibration test on the cylindrical rock core, the first strain value detected by the first strain gauge in the j-th group of strain gauges is recorded as The second strain value detected by the second strain gauge in the jth set of strain gauges is recorded as The first strain value detected by the first strain gauge in the jth group of strain gauges and the second strain value detected by the second strain gauge in the jth group of strain gauges Send to the computer; where j is a positive integer and 1≤j≤3;

[0035] Step 403: The computer calculates the The average circumferential strain value of the cylindrical core during the i-th confining pressure calibration test is obtained

[0036] The computer uses the formula The average axial strain value of the cylindrical rock core during the i-th confining pressure calibration test is obtained

[0037] Step 404: The computer calculates the The elastic modulus E of the cylindrical rock core measured in the i-th confining pressure calibration test is obtained i ; Wherein, R represents the outer diameter of the cylindrical core, and r represents the inner diameter of the cylindrical core;

[0038] The computer uses the formula Get the Poisson's ratio μ of the cylindrical rock core measured in the i-th confining pressure calibration test i ;

[0039] Step 405: The computer records the ratio of the height L of the cylindrical core to the outer diameter R of the cylindrical core as the height-to-diameter ratio of the cylindrical core. Computer and according to the formula Get the elastic modulus value of the cylindrical core The computer uses the formula Get the Poisson's ratio of the cylindrical core

[0040] Step 406: Use a computer to calculate the height-to-diameter ratio of the cylindrical core and the elastic modulus of the cylindrical core. As the ordinate, the elastic modulus values ​​of the cylindrical cores under different height-to-diameter ratios are plotted to obtain the elastic modulus curves under different height-to-diameter ratios;

[0041] The height-to-diameter ratio of the cylindrical core is used as the horizontal coordinate, and the Poisson's ratio of the cylindrical core is used as the horizontal coordinate. With y as the ordinate, the Poisson's ratio of the cylindrical core under different height-to-diameter ratios is plotted to obtain the Poisson's ratio curves under different height-to-diameter ratios.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1. The confining pressure calibration test device of the present invention has a simple structure, reasonable design, easy installation and layout, and low investment cost.

[0044] 2. The annular positioning plate used in the confining pressure calibration test device of the present invention is raised and lowered along the height direction of the rubber sleeve component, thereby effectively adapting to the situation where the height of the cylindrical rock core is smaller than the height of the rubber sleeve, thereby improving the adaptability range.

[0045] 3. The present invention provides a circular ring positioning plate, which is adjusted to rise and fall along the height direction of the rubber sleeve until the distance between the bottom of the circular ring positioning plate and the top of the cylindrical support is equal to the height of the cylindrical core, thereby reducing local stress concentration and tearing of the rubber sleeve.

[0046] 4. The confining pressure calibration test device of the present invention can not only adapt to the confining pressure calibration test of the cylindrical rock core containing the strain gauge obtained by sending the hollow inclusion strain gauge into the tunnel detection area by the casing stress relief method, but also meet the needs of other cylindrical rock core samples.

[0047] 5. The rubber sleeve component of the confining pressure calibration test device of the present invention and the pressure chamber in the confining pressure calibration chamber are coaxially arranged, thereby ensuring that the confining pressure applied by the pressure chamber to the outer wall of the cylindrical core is the same, meeting the confining pressure calibration test requirements.

[0048] 6. The confining pressure calibration test device of the present invention is provided with a rubber sleeve component, which can avoid damage to the cylindrical rock core and facilitate the application of the confining pressure requirement; in addition, the top and bottom of the rubber sleeve component are both openings, on the one hand, for the installation of the cylindrical rock core, and on the other hand, for the insertion of the connecting line of the strain gauge in the cylindrical rock core.

[0049] 7. The adopted confining pressure calibration test method has simple steps, is easy to implement and simple to operate, and improves the accuracy of the test of the physical parameters of the cylindrical rock core.

[0050] 8. The adopted confining pressure calibration test method is easy to operate and has good use effect. The first step is to adjust the lifting components, followed by the installation of the cylindrical core and the plunger rod, and then the confining pressure test is carried out on the cylindrical core. Finally, the strain data detected by the cylindrical core is processed for the mechanical parameters of the cylindrical core to obtain the elastic modulus value and Poisson's ratio value of the cylindrical core, thereby obtaining the elastic modulus curve under different height-to-diameter ratios and the Poisson's ratio curve under different height-to-diameter ratios, which is convenient for the subsequent analysis of the influence of the mechanical parameters of the cylindrical core under different height-to-diameter ratios.

[0051] In summary, the present invention has a reasonable design and low cost, and can effectively adapt to cylindrical cores of different lengths, thereby facilitating the subsequent analysis of the influence of mechanical parameters of cylindrical cores under different aspect ratios.

[0052] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a structural schematic diagram of the confining pressure calibration test device of the present invention.

[0054] Figure 2 for Figure 1 Top view of the .

[0055] Figure 3 for Figure 2 AA section view in.

[0056] Figure 4 It is a flowchart of the confining pressure calibration test method of the present invention.

[0057] Description of reference numerals:

[0058] 1—bottom plate; 2—lower sealing ring; 3—lower bottom plate;

[0059] 4—Oil filling pipe; 5—Locking screw; 6—Arc-shaped groove;

[0060] 7—upper top plate; 8—upper sealing ring; 9—top plate;

[0061] 10—plunger rod; 11—adjusting rod; 12—adjusting nut;

[0062] 13—lower nut; 14—rubber sleeve; 14-1—lower connecting plate;

[0063] 14-2—upper connecting plate; 17—middle cabin; 15—pressure chamber;

[0064] 16—Ring positioning plate. DETAILED DESCRIPTION

[0065] like Figures 1 to 3 A confining pressure calibration test device shown in the figure comprises a confining pressure calibration cabin, a lifting component arranged in the confining pressure calibration cabin, and a rubber sleeve component arranged at the center of the confining pressure calibration cabin and for mounting a cylindrical rock core, wherein the confining pressure calibration cabin is a hollow structure, a pressure chamber 15 is arranged in the confining pressure calibration cabin, the rubber sleeve component and the pressure chamber 15 are coaxially arranged, and the outer side wall of the rubber sleeve component is connected to the pressure chamber 15, and the cylindrical rock core is a cylindrical rock core with a strain gauge;

[0066] The lifting component includes a circular ring positioning plate 16 installed in the pressure chamber 15. The circular ring positioning plate 16 is sleeved outside the rubber sleeve component. The circular ring positioning plate 16 is lifted and lowered along the height direction of the rubber sleeve component.

[0067] In this embodiment, the circular ring positioning plate 16 is provided with an adjusting rod 11, and the number of the adjusting rod 11 is multiple, and the multiple adjusting rods 11 are evenly distributed along the circumferential direction of the edge of the circular ring positioning plate 16;

[0068] A lower nut 13 is provided on the top of the confining pressure rate cabin body, and an adjusting nut 12 is provided on the lower nut 13. The top end of the adjusting rod 11 passes through the pressure chamber 15, the lower nut 13 and the adjusting nut 12 in sequence, and the top end of the adjusting rod 11 extends out of the adjusting nut 12. The adjusting nut 12 and the adjusting rod 11 are threadedly connected.

[0069] In this embodiment, the confining pressure rating cabin comprises a bottom plate 1, a top plate 9 and an intermediate cabin 17 disposed between the bottom plate 1 and the top plate 9. The intermediate cabin 17 is a hollow structure. The center positions of the bottom plate 1 and the top plate 9 are respectively provided with central through holes for installing the rubber sleeve component.

[0070] The pressure chamber 15 is surrounded by an intermediate chamber 17 , an annular positioning plate 16 and an outer side wall of the rubber sleeve component. An oil filling pipe 4 communicating with the pressure chamber 15 is arranged on the intermediate chamber 17 .

[0071] In this embodiment, a lower bottom plate 3 is provided at the bottom of the intermediate cabin 17, an upper top plate 7 is provided at the top of the intermediate cabin 17, the upper top plate 7 and the top plate 9 are detachably connected, and the lower bottom plate 3 and the bottom plate 1 are detachably connected.

[0072] In this embodiment, the upper top plate 7, the top plate 9, the lower bottom plate 3 and the bottom plate 1 in the intermediate cabin 17 are provided with locking screws 5, and the number of the locking screws 5 is multiple, and the multiple locking screws 5 are evenly distributed along the circumferential direction of the outer wall of the intermediate cabin 17, and the bottom of the locking screws 5 is flush with the bottom of the bottom plate 1;

[0073] The outer side wall of the intermediate chamber 17 is provided with an arc-shaped groove 6 for the locking screw 5 to be inserted into, and the distance between the bottom of the arc-shaped groove 6 and the outer side wall of the intermediate chamber 17 is smaller than the diameter of the locking screw 5 .

[0074] In this embodiment, a plunger rod 10 is inserted into the rubber sleeve component, and the outer wall of the plunger rod 10 is in contact with the inner wall of the rubber sleeve component.

[0075] In this embodiment, the rubber sleeve component includes a rubber sleeve 14, the bottom end of the rubber sleeve 14 is flush with the bottom surface of the bottom plate 1 in the confining pressure rate cabin, the top end of the rubber sleeve 14 is flush with the top surface of the top plate 9 in the confining pressure rate cabin, and the outer side wall of the rubber sleeve 14 is connected to the pressure chamber 15.

[0076] In this embodiment, a lower connecting plate 14-1 is provided at the lower part of the rubber sleeve 14, and an upper connecting plate 14-2 is provided at the upper part of the rubber sleeve 14, and both the lower connecting plate 14-1 and the upper connecting plate 14-2 are circular ring plates;

[0077] The lower connecting plate 14 - 1 is located between the bottom of the middle cabin 17 and the bottom plate 1 , and the upper connecting plate 14 - 2 is located between the top of the middle cabin 17 and the top plate 9 .

[0078] In this embodiment, a lower sealing ring 2 is provided between the bottom of the intermediate cabin 17 and the bottom plate 1, and an upper sealing ring 8 is provided between the top of the intermediate cabin 17 and the top plate 9. The inner wall of the lower sealing ring 2 fits with the outer wall of the lower connecting plate 14-1, and the inner wall of the upper sealing ring 8 fits with the outer wall of the upper connecting plate 14-2.

[0079] In this embodiment, in actual use, the outer wall of the rubber sleeve 14 fits with the inner wall of the annular positioning plate 16 .

[0080] In this embodiment, in actual use, a sealing ring is provided at the connection between the rubber sleeve 14 and the annular positioning plate 16 .

[0081] In this embodiment, the annular positioning plate 16 is arranged to be lifted and lowered along the height direction of the rubber sleeve 14, thereby effectively adapting to the situation that the height of the cylindrical rock core is smaller than the height of the rubber sleeve, thereby improving the adaptability range.

[0082] In this embodiment, the confining pressure calibration test device can adapt to the confining pressure calibration test of cylindrical rock cores containing strain gauges, and can also meet the needs of other cylindrical rock core samples.

[0083] In this embodiment, the rubber sleeve 14 is provided to avoid damage to the cylindrical rock core and facilitate the application of confining pressure. In addition, the top and bottom of the rubber sleeve component are both openings, which are for the installation of the cylindrical rock core on the one hand and for the insertion of the connecting wire of the strain gauge in the cylindrical rock core on the other hand.

[0084] In this embodiment, the rubber sleeve 14 and the pressure chamber 15 are coaxially arranged to ensure that the confining pressure applied by the pressure chamber 15 to the outer wall of the cylindrical core is the same, meet the confining pressure calibration test requirements, and improve the accuracy of the test.

[0085] In this embodiment, the rubber sleeve 14 is located at the central through hole.

[0086] In this embodiment, the lower nut 13 is provided to limit the adjusting nut 12, so that during the screwing process of the adjusting nut 12, the rotation of the adjusting nut 12 is converted into the vertical linear motion of the adjusting rod 11, so that the adjusting rod 11 is adjusted to be lifted and lowered along the height direction of the rubber sleeve 14, and then the annular positioning plate 16 is lifted and lowered along the height direction of the rubber sleeve 14, so as to adapt to the confining pressure calibration test of cylindrical rock cores of different heights.

[0087] In this embodiment, the annular positioning plate 16 and the plunger rod 10 are arranged to cooperate with each other so that the bottom of the annular positioning plate 16 and the plunger rod 10 are flush with the top of the cylindrical rock core. This is to avoid tearing of the rubber sleeve 14 due to local stress concentration during the process of introducing hydraulic oil into the pressure chamber 15 through the oil filling pipe 4.

[0088] In this embodiment, a lower sealing ring 2 is provided, and the inner wall of the lower sealing ring 2 fits with the outer wall of the lower connecting plate 14-1, thereby realizing a sealed connection between the bottom plate 1 and the lower bottom plate 3; an upper sealing ring 8 is provided, and the inner wall of the upper sealing ring 8 fits with the outer wall of the upper connecting plate 14-2, thereby realizing a sealed connection between the top plate 9 and the upper top plate 7, thereby ensuring the sealing of the pressure chamber 15.

[0089] In this embodiment, locking screws 5 are provided in the upper top plate 7, the top plate 9, the lower bottom plate 3 and the bottom plate 1. The upper top plate 7, the top plate 9, the lower bottom plate 3 and the bottom plate 1 are connected as a whole through the locking screws 5, thereby improving the stability of the overall installation and avoiding the complexity of the installation.

[0090] In this embodiment, an arc-shaped groove 6 is provided to embed the locking screw 5. On the one hand, this is to allow the locking screw 5 to fit the outer surface of the intermediate cabin 17, thereby effectively limiting the radial movement of the intermediate cabin 17 and improving the overall stability. On the other hand, this is to reduce the entire cross-section of the device and facilitate its installation in other mechanical parameter equipment.

[0091] like Figure 4 A confining pressure rating test method as shown includes the following steps:

[0092] Step 1: Adjustment of lifting components:

[0093] Step 101, placing a cylindrical support at the bottom of the rubber sleeve 14 in the rubber sleeve component;

[0094] Step 102, according to the height L of the cylindrical core, adjust the annular positioning plate 16 to rise and fall along the height direction of the rubber sleeve 14 until the distance between the bottom of the annular positioning plate 16 and the top of the cylindrical support is equal to the height L of the cylindrical core; wherein the height L of the cylindrical core is less than the height of the rubber sleeve 14;

[0095] Step 2: Installation of cylindrical core and plunger rod:

[0096] Step 201, placing a cylindrical rock core in the rubber sleeve 14; wherein the bottom of the cylindrical rock core is in contact with the top of the cylindrical support, and the cylindrical rock core is obtained by sending a hollow inclusion strain gauge into the tunnel detection area by using a casing stress relief method, and the cross section of the cylindrical rock core is a circular ring;

[0097] Step 202, inserting the plunger rod 10 into the rubber sleeve 14 until the bottom of the plunger rod 10 fits with the top of the cylindrical rock core; wherein the outer wall of the plunger rod 10 fits with the inner wall of the rubber sleeve 14;

[0098] Step 3: Confining pressure test:

[0099] Step 301, connecting the oil injection pipe 4 on the confining pressure rate constant cabin to the oil injection pump;

[0100] Step 302, operate the oil injection pump to inject hydraulic oil into the pressure chamber 15 through the oil injection pipe 4 until the pressure in the pressure chamber 15 reaches 1 MPa, and perform the first confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber 15 in the first confining pressure calibration test on the cylindrical rock core is recorded as the first confining pressure value P1;

[0101] Step 303, repeating step 302 until the pressure in the pressure chamber 15 reaches 2 MPa, and performing a second confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber 15 in the second confining pressure calibration test on the cylindrical rock core is recorded as the second confining pressure value P2;

[0102] Step 304: Repeat step 303 multiple times to obtain the i-th confining pressure value P i and the i+1th confining pressure value P i+1 ; Among them, P i+1 -P i =1MPa;

[0103] Step 305: Repeat step 304 n times to obtain the nth confining pressure value P n ; Wherein, i and n are both positive integers, n≥5, 1≤i≤n;

[0104] Step 4: Mechanical parameter processing of cylindrical core:

[0105] Step 401: a first group of strain gauges, a second group of strain gauges and a third group of strain gauges are arranged in the cylindrical rock core, the first group of strain gauges, the second group of strain gauges and the third group of strain gauges are evenly distributed along the circumferential direction of the cylindrical rock core, and the first group of strain gauges, the second group of strain gauges and the third group of strain gauges each include two strain gauges, the two strain gauges are respectively a first strain gauge and a second strain gauge, the first strain gauge and the axis of the cylindrical rock core are at an angle of 90°, and the second strain gauge and the axis of the cylindrical rock core are parallel;

[0106] Step 402: During the i-th confining pressure calibration test on the cylindrical rock core, the first strain value detected by the first strain gauge in the j-th group of strain gauges is recorded as The second strain value detected by the second strain gauge in the jth set of strain gauges is recorded as The first strain value detected by the first strain gauge in the jth group of strain gauges and the second strain value detected by the second strain gauge in the jth group of strain gauges Send to the computer; where j is a positive integer and 1≤j≤3;

[0107] Step 403: The computer calculates the The average circumferential strain value of the cylindrical core during the i-th confining pressure calibration test is obtained

[0108] The computer uses the formula The average axial strain value of the cylindrical rock core during the i-th confining pressure calibration test is obtained

[0109] Step 404: The computer calculates the The elastic modulus E of the cylindrical rock core measured in the i-th confining pressure calibration test is obtained i ; Wherein, R represents the outer diameter of the cylindrical core, and r represents the inner diameter of the cylindrical core;

[0110] The computer uses the formula Get the Poisson's ratio μ of the cylindrical rock core measured in the i-th confining pressure calibration test i ;

[0111] Step 405: The computer records the ratio of the height L of the cylindrical core to the outer diameter R of the cylindrical core as the height-to-diameter ratio of the cylindrical core. Computer and according to the formula Get the elastic modulus value of the cylindrical core The computer uses the formula Get the Poisson's ratio of the cylindrical core

[0112] Step 406: Use a computer to calculate the height-to-diameter ratio of the cylindrical core and the elastic modulus of the cylindrical core. As the ordinate, the elastic modulus values ​​of the cylindrical cores under different height-to-diameter ratios are plotted to obtain the elastic modulus curves under different height-to-diameter ratios;

[0113] The height-to-diameter ratio of the cylindrical core is used as the horizontal coordinate, and the Poisson's ratio of the cylindrical core is used as the horizontal coordinate. With y as the ordinate, the Poisson's ratio of the cylindrical core under different height-to-diameter ratios is plotted to obtain the Poisson's ratio curves under different height-to-diameter ratios.

[0114] In this embodiment, the confining pressure calibration test method has simple steps, is easy to implement and simple to operate, and improves the accuracy of testing the physical parameters of the cylindrical rock core.

[0115] In this embodiment, the confining pressure calibration test method is easy to operate and has good use effect. First, the lifting component is adjusted, followed by the installation of the cylindrical core and the plunger rod, and then the confining pressure test is carried out on the cylindrical core. Finally, the strain data detected by the cylindrical core is processed for the mechanical parameters of the cylindrical core to obtain the elastic modulus value and Poisson's ratio value of the cylindrical core, thereby obtaining the elastic modulus curve under different height-to-diameter ratios and the Poisson's ratio curve under different height-to-diameter ratios, which is convenient for subsequent analysis of the influence of the mechanical parameters of the cylindrical core under different height-to-diameter ratios.

[0116] In summary, the present invention has a reasonable design and low cost, and can effectively adapt to cylindrical cores of different lengths, thereby facilitating the subsequent analysis of the influence of mechanical parameters of cylindrical cores under different aspect ratios.

[0117] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A confining pressure rating test device, characterized in that: It comprises a confining pressure rating cabin, a lifting component arranged in the confining pressure rating cabin, and a rubber sleeve component arranged at the center of the confining pressure rating cabin and for mounting a cylindrical rock core, the confining pressure rating cabin is a hollow structure, a pressure chamber (15) is arranged in the confining pressure rating cabin, the rubber sleeve component and the pressure chamber (15) are coaxially arranged, the outer side wall of the rubber sleeve component is in communication with the pressure chamber (15), and the cylindrical rock core is a cylindrical rock core with a strain gauge; The lifting component comprises a circular ring positioning plate (16) installed in the pressure chamber (15), the circular ring positioning plate (16) is sleeved outside the rubber sleeve component, and the circular ring positioning plate (16) is lifted and lowered along the height direction of the rubber sleeve component; The confining pressure rating cabin comprises a bottom plate (1), a top plate (9) and an intermediate cabin (17) arranged between the bottom plate (1) and the top plate (9); the intermediate cabin (17) is a hollow structure; the bottom plate (1) and the top plate (9) are respectively provided with central through holes for installing the rubber sleeve component at their central positions; The pressure chamber (15) is surrounded by an intermediate chamber (17), a circular ring positioning plate (16) and an outer side wall of the rubber sleeve component, and an oil injection pipe (4) communicating with the pressure chamber (15) is provided on the intermediate chamber (17); A plunger rod (10) is inserted into the rubber sleeve component, and the outer wall of the plunger rod (10) is in contact with the inner wall of the rubber sleeve component; The rubber sleeve component comprises a rubber sleeve (14), the bottom end of the rubber sleeve (14) is flush with the bottom surface of the bottom plate (1) in the confining pressure rate cabin, the top end of the rubber sleeve (14) is flush with the top surface of the top plate (9) in the confining pressure rate cabin, and the outer side wall of the rubber sleeve (14) is connected to the pressure chamber (15); A first group of strain gauges, a second group of strain gauges and a third group of strain gauges are arranged in the cylindrical rock core. The first group of strain gauges, the second group of strain gauges and the third group of strain gauges are evenly distributed along the circumferential direction of the cylindrical rock core, and the first group of strain gauges, the second group of strain gauges and the third group of strain gauges each include two strain gauges, the two strain gauges are respectively a first strain gauge and a second strain gauge, the angle between the first strain gauge and the axis of the cylindrical rock core is 90°, and the second strain gauge is parallel to the axis of the cylindrical rock core.

2. A confining pressure calibration test device according to claim 1, characterized in that: The annular positioning plate (16) is provided with an adjusting rod (11), the number of the adjusting rods (11) is multiple, and the multiple adjusting rods (11) are evenly distributed along the circumferential direction of the edge of the annular positioning plate (16); A lower nut (13) is arranged on the top of the confining pressure rate cabin body, and an adjusting nut (12) is arranged on the lower nut (13); the top end of the adjusting rod (11) passes through the pressure chamber (15), the lower nut (13) and the adjusting nut (12) in sequence; the top end of the adjusting rod (11) extends out of the adjusting nut (12); and the adjusting nut (12) and the adjusting rod (11) are threadedly connected.

3. A confining pressure calibration test device according to claim 1, characterized in that: The bottom of the intermediate cabin (17) is provided with a lower bottom plate (3), and the top of the intermediate cabin (17) is provided with an upper top plate (7). The upper top plate (7) and the top plate (9) are detachably connected, and the lower bottom plate (3) and the bottom plate (1) are detachably connected.

4. A confining pressure calibration test device according to claim 1, characterized in that: The upper top plate (7), the top plate (9), the lower bottom plate (3) and the bottom plate (1) in the intermediate cabin (17) are provided with locking screws (5), the number of the locking screws (5) is multiple, and the multiple locking screws (5) are evenly distributed along the circumferential direction of the outer wall of the intermediate cabin (17), and the bottom of the locking screws (5) is flush with the bottom of the bottom plate (1); The outer side wall of the intermediate cabin (17) is provided with an arc-shaped groove (6) for the locking screw (5) to be embedded, and the distance between the bottom of the arc-shaped groove (6) and the outer side wall of the intermediate cabin (17) is smaller than the diameter of the locking screw (5).

5. A confining pressure calibration test device according to claim 1, characterized in that: A lower connecting plate (14-1) is provided at the lower part of the rubber sleeve (14), and an upper connecting plate (14-2) is provided at the upper part of the rubber sleeve (14); both the lower connecting plate (14-1) and the upper connecting plate (14-2) are circular ring plates; The lower connecting plate (14-1) is located between the bottom of the middle cabin (17) and the bottom plate (1), and the upper connecting plate (14-2) is located between the top of the middle cabin (17) and the top plate (9).

6. A confining pressure calibration test device according to claim 5, characterized in that: A lower sealing ring (2) is arranged between the bottom of the intermediate cabin (17) and the bottom plate (1), and an upper sealing ring (8) is arranged between the top of the intermediate cabin (17) and the top plate (9). The inner wall of the lower sealing ring (2) is in contact with the outer wall of the lower connecting plate (14-1), and the inner wall of the upper sealing ring (8) is in contact with the outer wall of the upper connecting plate (14-2).

7. A method for conducting a confining pressure calibration test on a cylindrical rock core using the device as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1: Adjustment of lifting components: Step 101, placing a cylindrical support at the bottom of the rubber sleeve (14) in the rubber sleeve component; Step 102, according to the height L of the cylindrical rock core, adjusting the circular ring positioning plate (16) to rise and fall along the height direction of the rubber sleeve (14) until the distance between the bottom of the circular ring positioning plate (16) and the top of the cylindrical support is equal to the height L of the cylindrical rock core; wherein the height L of the cylindrical rock core is less than the height of the rubber sleeve (14); Step 2: Installation of cylindrical core and plunger rod: Step 201, placing a cylindrical rock core in the rubber sleeve (14); wherein the bottom of the cylindrical rock core is in contact with the top of the cylindrical support, the cylindrical rock core is a cylindrical rock core containing a strain gauge obtained by sending a hollow inclusion strain gauge into a tunnel detection area using a casing stress relief method, and the cross section of the cylindrical rock core is a circular ring; Step 202, inserting the plunger rod (10) into the rubber sleeve (14) until the bottom of the plunger rod (10) fits with the top of the cylindrical rock core; wherein the outer wall of the plunger rod (10) fits with the inner wall of the rubber sleeve (14); Step 3: Confining pressure test: Step 301, connecting the oil injection pipe (4) on the confining pressure rate setting cabin to the oil injection pump; Step 302, operate the oil injection pump to inject hydraulic oil into the pressure chamber (15) through the oil injection pipe (4) until the pressure in the pressure chamber (15) reaches 1 MPa, and perform a first confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber (15) in the first confining pressure calibration test on the cylindrical rock core is recorded as the first confining pressure value P1; Step 303, repeating step 302 until the pressure in the pressure chamber (15) is 2 MPa, and performing a second confining pressure calibration test on the cylindrical rock core; wherein the pressure in the pressure chamber (15) in the second confining pressure calibration test on the cylindrical rock core is recorded as the second confining pressure value P2; Step 304: Repeat step 303 multiple times to obtain the i-th confining pressure value P i and the i+1th confining pressure value P i+1 ; Among them, P i+1 -P i =1MPa; Step 305: Repeat step 304 n times to obtain the nth confining pressure value P n ; Wherein, i and n are both positive integers, n≥5, 1≤i≤n; Step 4: Mechanical parameter processing of cylindrical core: Step 401: a first group of strain gauges, a second group of strain gauges and a third group of strain gauges are arranged in the cylindrical rock core, the first group of strain gauges, the second group of strain gauges and the third group of strain gauges are evenly distributed along the circumferential direction of the cylindrical rock core, and the first group of strain gauges, the second group of strain gauges and the third group of strain gauges each include two strain gauges, the two strain gauges are respectively a first strain gauge and a second strain gauge, the first strain gauge and the axis of the cylindrical rock core are at an angle of 90°, and the second strain gauge and the axis of the cylindrical rock core are parallel; Step 402: During the i-th confining pressure calibration test on the cylindrical rock core, the first strain value detected by the first strain gauge in the j-th group of strain gauges is recorded as The second strain value detected by the second strain gauge in the jth set of strain gauges is recorded as The first strain value detected by the first strain gauge in the jth group of strain gauges and the second strain value detected by the second strain gauge in the jth group of strain gauges Send to the computer; where j is a positive integer and 1≤j≤3; Step 403: The computer calculates the The average circumferential strain value of the cylindrical core during the i-th confining pressure calibration test is obtained The computer uses the formula The average axial strain value of the cylindrical rock core during the i-th confining pressure calibration test is obtained Step 404: The computer calculates the The elastic modulus E of the cylindrical rock core measured in the i-th confining pressure calibration test is obtained i ; Wherein, R represents the outer diameter of the cylindrical core, and r represents the inner diameter of the cylindrical core; The computer uses the formula Get the Poisson's ratio μ of the cylindrical rock core measured in the i-th confining pressure calibration test i ; Step 405: The computer records the ratio of the height L of the cylindrical core to the outer diameter R of the cylindrical core as the height-to-diameter ratio of the cylindrical core. Computer and according to the formula Get the elastic modulus value of the cylindrical core The computer uses the formula Get the Poisson's ratio of the cylindrical core Step 406: Use a computer to calculate the height-to-diameter ratio of the cylindrical core and the elastic modulus of the cylindrical core. As the ordinate, the elastic modulus values ​​of the cylindrical cores under different height-to-diameter ratios are plotted to obtain the elastic modulus curves under different height-to-diameter ratios; The height-to-diameter ratio of the cylindrical core is used as the horizontal coordinate, and the Poisson's ratio of the cylindrical core is used as the horizontal coordinate. With y as the ordinate, the Poisson's ratio of the cylindrical core under different height-to-diameter ratios is plotted to obtain the Poisson's ratio curves under different height-to-diameter ratios.

Images