CN210893952U - Precision measurement test device for poisson ratio of shallow soft sediment - Google Patents

Abstract

The utility model belongs to the technical field of geotechnical engineering tests, and relates to a precise measurement and test device for Poisson's ratio of shallow soft sediments. The device comprises a pressure controller, a hydraulic controller, a computer, a triaxial instrument and a volume compensation system and a high-precision deformation measurement system; the volume compensation system is placed inside the triaxial instrument and connected to the pressure controller; the high-precision deformation measurement system is placed outside the triaxial instrument and connected to the pressure controller and the hydraulic controller respectively; the computer is separately Connected to pressure controller and hydraulic controller. The utility model provides a shallow soft sediment Poisson which can measure the lateral deformation and longitudinal deformation of the sediment soil sample under the in-situ stress state and obtain the Poisson's ratio, less disturbance to the soil sample and high precision Ratio of precision measurement test equipment.

Description

A Precise Measurement Test Device for Poisson's Ratio of Shallow Soft Sediments

technical field

The utility model belongs to the technical field of geotechnical engineering tests, and relates to a precise measurement test device for Poisson's ratio of shallow soft sediments, in particular to a high-precision measurement test for obtaining the Poisson's ratio of shallow soft sediments on the seabed device.

Background technique

Poisson's ratio is an important parameter in geotechnical engineering. It is the absolute value of the ratio of the lateral strain to the longitudinal strain of the soil sample in the small elastic deformation range, and it is a constant that reflects the lateral deformation characteristics of the material. At present, there are many methods for measuring Poisson's ratio of soil, such as conventional strain gauge method, digital image technology method, CT scanning method and measured wave velocity method. However, the conventional strain gauge method is mainly aimed at objects with high rigidity. For the shallow bottom sediment soil with low rigidity, the strain gage cannot be effectively embedded and fixed on the measured sediment soil sample; digital image The technical method has the problems of the liquid refraction in the triaxial confining pressure chamber and the numerical correction of the three-dimensional to two-dimensional plane image; the CT scanning method is not only expensive, but also difficult to restore the sediment soil sample to the original stress state for measurement; the measured wave velocity In addition to the very high requirements for sample coupling, once the soil contains air bubbles, the air bubbles can significantly attenuate the wave propagation, resulting in inaccurate measurement. Submarine shallow sediments generally have the characteristics of soft structure, low strength, low stiffness, and force sensitivity. In the test, if the rubber film is used to wrap the sample, the rubber mold has a constraining effect on the lateral deformation of the sample, and this constraining effect cannot be ignored for the high-precision Poisson's ratio measurement. Therefore, for shallow soft sediments, the restraint effect of the rubber mold must be removed in the experiment to obtain the Poisson's ratio.

Utility model content

In order to solve the above-mentioned technical problems existing in the background technology, the utility model provides a method that can directly measure the lateral deformation and longitudinal deformation of the sediment soil sample under the in-situ stress state, and obtain its Poisson's ratio, so as to disturb the soil sample. Small and high precision shallow soft sediment Poisson's ratio precision measurement test device.

In order to achieve the above purpose, the utility model adopts the following technical solutions:

A precise measurement test device for Poisson's ratio of shallow soft sediments, characterized in that: the precise measurement test device for Poisson's ratio of shallow soft sediments includes a pressure controller, a hydraulic controller, a computer, a triaxial instrument, volume compensation system and high-precision deformation measurement system; the volume compensation system is placed inside the triaxial instrument and is connected with the pressure controller; the high-precision deformation measurement system is placed outside the triaxial instrument and is respectively connected with the pressure controller The computer is connected with the pressure controller and the hydraulic controller; the computer is respectively connected with the pressure controller and the hydraulic controller.

Preferably, the triaxial instrument used in the present invention includes a sample base, and the triaxial pressure chamber is made of transparent toughened materials (under constant temperature conditions, the pressure is less than or equal to 15MPa and the volume remains unchanged); the volume compensation system includes a base with the sample base. Connected compensator; the top of the compensator communicates with the pressure controller.

Preferably, the compensator used in the present invention includes a compensator valve, a compensator head, a compensator cavity, an O-ring, a shaft sleeve, a compensator rod and a bayonet; the shaft sleeve has a compensator cavity; The compensation rod is placed in the inner cavity of the compensator of the shaft sleeve and can move freely along the axial direction of the shaft sleeve; the bottom of the compensation rod is connected with the sample base through the bayonet and moves synchronously with the sample base; the compensator The valve communicates with the inner cavity of the compensator through the compensator head; the pressure controller communicates with the compensator valve; an O-ring is arranged between the compensating rod and the shaft sleeve.

Preferably, the high-precision deformation measurement system used in the present invention includes a soil sample longitudinal deformation measurement device and a soil sample lateral deformation measurement device; the soil sample longitudinal deformation measurement device is placed at the bottom of the sample base and connected to the sample base ; The hydraulic controller drives the sample base to move up and down along the axial direction of the triaxial instrument through the soil sample longitudinal deformation measurement device; the soil sample lateral deformation measurement device is placed outside the triaxial instrument; the pressure controller is connected to the soil sample. The lateral deformation measuring device is connected.

Preferably, the soil sample longitudinal deformation measurement device used in the present invention includes a lifting column, a displacement sensor and a hydraulic chamber; the hydraulic chamber is connected with the sample base through the lifting column; the hydraulic controller is communicated with the hydraulic chamber and is connected through the hydraulic chamber. The hydraulic chamber and the lifting column drive the sample base to move up and down along the axial direction of the triaxial instrument; the displacement sensor is connected to the lifting column and is parallel; the end of the displacement sensor rests on the upper surface of the hydraulic chamber.

Preferably, the cross-sectional area of the lifting column used in the present invention is the same as the cross-sectional area of the compensation rod.

Preferably, the soil sample lateral deformation measurement device used in the present invention includes a high-resolution CCD camera, a pressure-resistant transparent glass tube, a lift-type bracket and a pressure chamber body variable valve; the high-resolution CCD camera (pixels of the CCD camera) Point size ≤ 1 μm) is set on the top of the triaxial instrument through a lifting bracket; the pressure-resistant transparent glass tube is communicated with the interior of the triaxial instrument through the pressure chamber volume change valve; the pressure controller is communicated with the pressure-resistant transparent glass tube ; The interior of the triaxial instrument is filled with mineral oil during operation; the mineral oil overflows from the triaxial instrument and remains in a pressure-resistant transparent glass tube to form an oil-water interface; the lens of the high-resolution CCD camera is aligned oil-water interface.

Preferably, the triaxial instrument used in the present invention also includes a triaxial pressure chamber, a pressure chamber base, an oil inlet/discharge port, an exhaust hole, an axial stress sensor, a split die, a support column, a bearing platform and a nut The triaxial pressure chamber and the pressure chamber base are sequentially connected from top to bottom to form a cavity; the bottom of the pressure chamber base is provided with an oil inlet/outlet port; the top of the triaxial pressure chamber is provided with an exhaust hole; The exhaust hole is provided with a nut matching the structure of the end of the exhaust hole; the axial stress sensor is placed on the top of the triaxial pressure chamber; the sample base is placed on the triaxial pressure chamber and the pressure chamber base In the formed cavity; the split mold is placed on the sample base; the pressure chamber base is fixed on the bearing platform through the support column; the mineral oil is filled in the triaxial pressure chamber and the pressure chamber base. into the cavity and overflow from the cavity into a pressure-resistant transparent glass tube.

The advantages of the utility model are:

The utility model provides a precise measurement test device for Poisson's ratio of shallow soft sediments, which comprises a pressure controller, a hydraulic controller, a computer, a triaxial instrument, a volume compensation system and a high-precision deformation measurement system; The volume compensation system is placed inside the triaxial instrument and connected with the pressure controller; the high-precision deformation measurement system is placed outside the triaxial instrument and is connected with the pressure controller and the hydraulic controller respectively; the computer is respectively connected with the pressure controller and the hydraulic controller connected. The utility model adopts a volume compensation system, so that the volume change of the soil sample is equal to the volume change of the mineral oil in the triaxial pressure chamber; the triaxial pressure chamber is pressurized with mineral oil to remove the deformation constraint effect of the rubber film on the soil sample, The measured value can more truly reflect the real deformation state of the soft sediment soil sample; the utility model has little disturbance to the sediment soil sample, can restore the sediment soil sample to the original stress state for measurement, and removes the rubber film. impact, the results are more accurate.

Description of drawings

Fig. 1 is the structural representation of the measuring device of Poisson's ratio of shallow soft sediment provided by the utility model;

Fig. 2 is the overall structure schematic diagram of the device provided by the present utility model;

Wherein, the names corresponding to the drawing numbers in the accompanying drawings are:

1-compensator; 11-compensator valve; 12-compensator head; 13-compensator cavity; 14-O-ring; 15-shaft sleeve; 16-compensation rod; 17-bayonet; 2-high resolution CCD camera; 21-pressure-resistant transparent glass tube; 22-oil-water interface; 23-lifting bracket; 24-pressure chamber body variable valve; 25-lifting column; 26-displacement sensor; 27-hydraulic chamber; 3-soil sample 31-Triaxial pressure chamber; 32-Axial stress sensor; 33-Mineral oil; 34-Split mold; 35-Sample base; 36-Pressure chamber base; ; 39-cap; 40-nut; 41-vent; 42-triaxial instrument; 43-pressure controller; 44-hydraulic controller; 45-computer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the embodiments and operation process of the present invention will be described in detail below with reference to the examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention. Hereinafter, the structural composition, working principle and application method of the present invention will be described with reference to the accompanying drawings and specific embodiments.

Referring to FIG. 1 and FIG. 2 , the present invention provides a precise measuring device for Poisson’s ratio of shallow soft sediments, including a pressure controller 43 , a hydraulic controller 44 , a computer 45 , a triaxial instrument 42 , a volume compensation system and The high-precision deformation measurement system; the volume compensation system is placed inside the triaxial instrument 42 and connected to the pressure controller 43; the high-precision deformation measurement system is placed outside the triaxial instrument 42 and is respectively connected with the pressure controller 43 and the hydraulic controller 44 connected; the computer 45 is connected to the pressure controller 43 and the hydraulic controller 44 respectively.

The volume compensation system consists of the compensator 1 , the compensator valve 11 , and the bayonet 17 to form an independent volume compensation system. The compensator 1 includes a compensator valve 11 , a compensator head 12 , a compensator inner cavity 13 , an O-ring 14 , a shaft sleeve 15 and a compensator rod 16 . The shaft sleeve 15 of the compensator 1 is installed inside the triaxial pressure chamber 31, the O-ring 14 is installed in the shaft sleeve 15, and the compensation rod 16 is located in the shaft sleeve 15; the compensator valve 11 is installed on the top of the triaxial pressure chamber 31, and the The compensator valve 11 communicates with the compensator head 12 ; the bayonet 17 is installed on the compensator rod 16 . The O-ring 14 seals the inner cavity 13 of the compensator, so that the inner cavity 13 of the compensator and the triaxial pressure chamber 31 are not connected to each other. During the test, the pressure in the inner cavity 13 of the compensator and the triaxial pressure chamber 31 can be controlled by the The controllers 43 are independently controlled respectively, so that the compensation rod 16 and the bayonet 17 are always in close contact; the cross-sectional area of the compensation rod 16 is the same as the cross-sectional area of the lifting column 25. When the pressure of the hydraulic chamber 27 pushes the lifting column 25 When moving upward, the fixed bayonet 17 on the sample base 35 can synchronously push the compensation rod 16 to move, eliminating the volume change of the mineral oil 33 caused by the entry and exit of the lifting column 25 into the triaxial pressure chamber 31, that is, V _row =V _complement , so that the three The volume change of the mineral oil 33 in the axial pressure chamber 31 is only related to the volume change of the sediment soil sample 3, and has nothing to do with the instrument itself. The triaxial pressure chamber 31 is filled with mineral oil 33, which is preferably transparent and incompressible mineral oil.

The high-precision deformation measurement system uses the displacement sensor 26 and the high-resolution CCD camera 2 as measurement means, and can directly measure the longitudinal deformation and lateral deformation of the sediment soil sample 3 with high precision. The longitudinal deformation of the sediment sample is measured by the lifting column 25, the displacement sensor 26, and the hydraulic chamber 27; the lateral deformation of the sediment sample is measured by the high-resolution CCD camera 2, the pressure-resistant transparent glass tube 21, the oil-water interface 22, and the lifting bracket 23. Measurement of pressure chamber body variable valve 24.

In measuring the longitudinal deformation of the sediment soil sample, the displacement sensor 26 is fixed in parallel with the lifting column 25, and at the same time, the bottom probe of the displacement sensor 26 is in close contact with the convex point on the top of the hydraulic chamber 27; The column 25 moves upward, and the bottom probe of the displacement sensor 26 measures the displacement of the lifting column 25, thereby obtaining the displacement of the soil sample 3, that is, the longitudinal deformation Δl. In measuring the lateral deformation of soil samples, it is necessary to adjust the height of the high-resolution CCD camera 2 on the lifting bracket 23 to the oil-water interface 22 in the pressure-resistant transparent glass tube 21; the pressure chamber variable valve 24 is installed on the three-axis The top of the pressure chamber 31 is connected to each other; the pressure-resistant transparent glass 21 is vertically fixed on the top of the pressure chamber variable valve 24; change, so as to measure the total volume change of soil sample 3, that is, the volume deformation ΔV. Among them, high-resolution CCD camera 2; pressure-resistant transparent glass tube 21 (quartz transparent pressure-resistant glass tube, inner diameter 2-5mm, pressure resistance ≥15MPa) should have the characteristics of high rigidity, high pressure resistance and small inner diameter. Finally, the measured longitudinal deformation and transverse deformation of the soil sample are converted into longitudinal strain and transverse strain, where the strain is the ratio of the deformation amount Δl to the original size l, which is represented by ε, namely:

Where ε is dimensionless, usually expressed as a percentage. Thus there are:

in:

Δl——Axial deformation of sediment soil sample in mm;

l——initial length of sediment sample in mm;

_Initial V - volume change of sediment soil sample mm ³ ;

ΔV——initial volume of sediment soil sample mm ³ ;

ε ₁ — longitudinal strain of sediment soil sample;

ε _v ——the volume change of sediment soil sample;

ε ₂ — lateral strain of sediment soil sample;

ν—Poisson’s ratio of sediment samples.

The triaxial pressure chamber system is similar to the conventional geotechnical triaxial pressure chamber, and consists of a triaxial instrument 42 , an external pressure controller 43 and an external hydraulic controller 44 . The triaxial instrument 42 includes a triaxial pressure chamber 31 , an axial stress sensor 32 , a sample base 35 , a pressure chamber base 36 , an oil inlet/outlet 37 , a support column 38 , a bearing platform 39 , a nut 40 , and an exhaust hole 41 . The pressure chamber base 36 is fixed on the platform 39 by three support columns 38; the oil inlet/outlet 37 is installed at the lower part of the pressure chamber base 36; the split mold 34 is fixed on the sample base 35 to form a cylindrical cavity, which is Prepare the sediment soil sample 3 in the cylindrical cavity or directly put the processed sediment soil sample 3 into the cylindrical cavity; the triaxial pressure chamber 31 is connected with the pressure chamber base 36; the axial stress sensor 32 is installed on the triaxial The upper part of the pressure chamber 31; the nozzle on the pressure controller 43 is connected to the pressure-resistant transparent glass tube 21; the mineral oil 33 fills the entire interior of the triaxial pressure chamber 31, and its highest oil-water interface 22 reaches the scale on the pressure-resistant transparent glass tube 21 The line is 200mm to 300mm from the bottom end of the glass tube; the nut 40 is installed on the upper part of the triaxial pressure chamber 31 . Among them, mineral oil 33 belongs to the non-wetting phase fluid, and has the characteristics that water and gas are incompatible, which can effectively protect the original state of sediment soil sample 3, and its compressibility is much lower than that of water, and its own volume under high pressure conditions The change is small and negligible, thus satisfying the measurement of the high-precision volume-variant Poisson's ratio of soil sample 3; wherein the nut 40 is matched with the vent hole 41 .

The utility model proposes a precise measurement test device for Poisson's ratio of shallow soft sediments. The particle size of the seabed clay is less than 0.075mm and the moisture content of the dry soil is 2.5%, using the Chinese patent No. ZL201310752757.1 titled "Pressure controllable gas replacement reaction device and its application in the preparation of air-containing soil samples" disclosed in A method for preparing air-bearing soil samples by means of zeolite to prepare remodeled air-bearing sediment soil samples, the diameter d is 50mm, the height h is 100mm, and the air content is 1%. The Poisson's ratio is measured according to the following steps. The experiments were carried out under constant temperature conditions:

1) The pressure chamber base 36 is horizontally fixed on the platform 39 with the support column 38; then the hydraulic pressure chamber 27 is depressurized by the hydraulic controller 44, and the lifting column 25 is lowered to the bottom; and then the displacement sensor 26 and the hydraulic chamber 27 are adjusted. The bumps on the top are in close contact.

2) Fix the split mold 34 on the sample base 35, and put the prepared sediment soil sample 3 into the split mold 34; then fix the bayonet 17 and the sample base 35 horizontally.

3) Pass the mineral oil 33 through the oil inlet/outlet port 37. When the mineral oil 33 submerges the soil sample 3, close the oil inlet/outlet port 37, then release the split mold 34 and take it out slowly to make the soil sample 3 soft able to maintain the original state.

4) Open the compensator valve 11 and communicate with the compensator head 12; install the O-ring 14 in the shaft sleeve 15, push the compensating rod 16 to the bottom of the shaft sleeve 15, close the compensator valve 11; put the axial stress sensor 32 is adjusted to the highest position, and the triaxial pressure chamber 31 is screwed on the pressure chamber base 36; adjust the axial stress sensor 32 to contact the top of the soil sample 3, and then slowly open the compensator valve 11, lower the compensator 1 in the compensator rod 16 and The bayonet 17 contacts.

5) Open the oil inlet/discharge port 37 and continue to feed the mineral oil 33 into the triaxial pressure chamber 31. When the mineral oil 33 is approaching the top of the triaxial pressure chamber 31, tilt the device 1-3o so that the exhaust hole 41 is at the top of the triaxial pressure chamber 31. At the highest point, after the air in the triaxial pressure chamber 31 is exhausted, close the oil inlet/discharge port 37, seal the exhaust hole 41 with the nut 40, and then level the device; then slowly open the oil inlet/discharge port 37 to continue Pour in the mineral oil 33, make the mineral oil 33 reach the scale line marked on the side wall of the pressure-resistant transparent glass tube 21, close the oil inlet/outlet port 37; adjust the height of the high-resolution CCD camera 2 on the lift bracket 23, The lens of the high-resolution CCD camera 2 is aimed at the oil-water interface 22 in the pressure-resistant transparent glass tube 21 .

6) Connect the compensator valve 11 and the pressure-resistant transparent glass tube 21 to the corresponding interfaces of the pressure controller 43, and open the compensator valve 11 and the pressure chamber body change valve 24.

7) The computer 45 sets the pressure value of the pressure controller 43 to 50kPa to pressurize the mineral oil 33 in the triaxial pressure chamber 31 (the control software is all a mature software operating system), and the soil sample 3 is made by the confining pressure of the mineral oil 33. The stress state when it is restored to its original position (surface deposits at a water depth of 5m); record the scale value at the oil-water interface 22 in the pressure-resistant transparent glass tube 21 at this time as the volume zero value; then set the hydraulic controller by the computer 45 44 Adjust the lift height of the lift column 25 .

8) The height change of the lifting column 25 recorded by the displacement sensor 26 is 0.0095mm; the volume change of the oil-water interface 22 in the pressure-resistant transparent glass tube 21 after the elevation is observed by the high-resolution CCD camera 2 is -1883.862mm ^3. Substituting into formulas ② and ③, the longitudinal strain and volumetric strain of soil sample 3 are obtained as:

Substitute into formulas ④ and ⑤ to have:

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection of the utility model.

Claims (7)

1. The utility model provides a shallow layer soft deposit poisson's ratio's precision measurement test device which characterized in that: the device for precisely measuring the Poisson's ratio of the shallow soft sediment comprises a pressure controller (43), a hydraulic controller (44), a computer (45), a triaxial apparatus (42), a volume compensation system and a high-precision deformation measurement system; the volume compensation system is arranged inside the triaxial apparatus (42) and is connected with the pressure controller (43); the high-precision deformation measuring system is arranged outside the triaxial apparatus (42) and is respectively connected with the pressure controller (43) and the hydraulic controller (44); the computer (45) is respectively connected with the pressure controller (43) and the hydraulic controller (44).

2. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 1, wherein: the triaxial apparatus (42) comprises a sample base (35), and the volume compensation system comprises a compensator (1) connected with the sample base (35); the top of the compensator (1) is communicated with a pressure controller (43).

3. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 2, wherein: the compensator (1) comprises a compensator valve (11), a compensator head (12), a compensator inner cavity (13), an O-shaped ring (14), a shaft sleeve (15), a compensating rod (16) and a bayonet (17); a compensator inner cavity (13) is arranged in the shaft sleeve (15); the compensation rod (16) is arranged in a compensator inner cavity (13) of the shaft sleeve (15) and can freely move along the axial direction of the shaft sleeve (15); the bottom of the compensating rod (16) is connected with the sample base (35) through a bayonet (17) and moves synchronously with the sample base (35); the compensator valve (11) is communicated with the compensator inner cavity (13) through a compensator head (12); the pressure controller (43) is communicated with the compensator valve (11); an O-shaped ring (14) is arranged between the compensation rod (16) and the shaft sleeve (15).

4. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 3, wherein: the high-precision deformation measuring system comprises a soil sample longitudinal deformation measuring device and a soil sample transverse deformation measuring device; the soil sample longitudinal deformation measuring device is arranged at the bottom of the sample base (35) and connected with the sample base (35); the hydraulic controller (44) drives the sample base (35) to move up and down along the axial direction of the triaxial apparatus (42) through the soil sample longitudinal deformation measuring device; the soil sample transverse deformation measuring device is arranged outside the triaxial apparatus (42); the pressure controller (43) is communicated with the soil sample transverse deformation measuring device; the soil sample longitudinal deformation measuring device comprises a lifting column (25), and the cross sectional area of the lifting column (25) is the same as that of the compensating rod (16).

5. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 4, wherein: the soil sample longitudinal deformation measuring device further comprises a displacement sensor (26) and a hydraulic chamber (27); the hydraulic chamber (27) is connected with a sample base (35) through a lifting column (25); the hydraulic controller (44) is communicated with the hydraulic chamber (27) and drives the sample base (35) to move up and down along the axial direction of the triaxial apparatus (42) through the hydraulic chamber (27) and the lifting column (25); the displacement sensor (26) is connected with the lifting column (25) and is parallel to the lifting column; the end of the displacement sensor (26) rests against the upper surface of the hydraulic chamber (27).

6. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 5, wherein: the soil sample transverse deformation measuring device comprises a high-resolution CCD camera (2), a pressure-resistant transparent glass tube (21), a lifting support (23) and a pressure chamber body variable valve (24); the high-resolution CCD camera (2) is arranged at the top of the triaxial apparatus (42) through a lifting support (23); the pressure-resistant transparent glass tube (21) is communicated with the inside of the triaxial apparatus (42) through a pressure chamber body variable valve (24); the pressure controller (43) is communicated with the pressure-resistant transparent glass tube (21); the interior of the triaxial apparatus (42) is filled with mineral oil (33) during operation; the mineral oil (33) overflows from the inside of the triaxial apparatus (42) and is kept in the pressure-resistant transparent glass tube (21) and forms an oil-water interface (22); the lens of the high-resolution CCD camera (2) is aligned to an oil-water interface (22).

7. The apparatus for precisely measuring the poisson's ratio of shallow soft sediment as claimed in claim 6, wherein: the triaxial apparatus (42) further comprises a triaxial pressure chamber (31), a pressure chamber base (36), an oil inlet/outlet (37), an exhaust hole (41), an axial stress sensor (32), a split mold (34), a support column (38), a bearing platform (39) and a screw cap (40); the three-axis pressure chamber (31) and the pressure chamber base (36) are sequentially connected from top to bottom to form a cavity; an oil inlet/outlet (37) is arranged at the bottom of the pressure chamber base (36); the top of the triaxial pressure chamber (31) is provided with an exhaust hole (41); the exhaust hole (41) is provided with a screw cap (40) matched with the end structure of the exhaust hole (41); the axial stress sensor (32) is arranged at the top of the triaxial pressure chamber (31); the sample base (35) is arranged in a cavity formed by the triaxial pressure chamber (31) and the pressure chamber base (36); the split mold (34) is arranged on a sample base (35); the pressure chamber base (36) is fixed on a bearing platform (39) through a supporting column (38); the mineral oil (33) fills the cavity formed by the triaxial pressure chamber (31) and the pressure chamber base (36) and overflows from the cavity into the pressure-resistant transparent glass tube (21).

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