Rock Testing Triaxial Pressure Chamber

Abstract

The present invention discloses a triaxial pressure chamber for rock testing, comprising a pressure transmission cylinder and a base, wherein the top of the pressure transmission cylinder is used to be connected to the top of a loading frame, the bottom of the base is used to be connected to the bottom of the loading frame, and the base and the pressure transmission cylinder are coaxially arranged; a hollow portion for accommodating a piston of a loading oil cylinder is arranged inside the pressure transmission cylinder, and a space for placing a sample is reserved between the base and the pressure transmission cylinder; the pressure bearing cylinder is also included, wherein the upper part of the pressure bearing cylinder is sleeved on the pressure transmission cylinder, and the lower part is sleeved on the base, forming a test chamber for placing the sample, and the pressure bearing cylinder is slidably connected with the pressure transmission cylinder and the base to open or close the test chamber. The purpose of the present invention is to provide a triaxial pressure chamber for rock testing in view of the problem of low test efficiency of existing buckle-type and bolt-fastened triaxial pressure chambers. The triaxial pressure chamber uses an axially liftable pressure bearing cylinder to form a sample test chamber, thereby significantly improving the test efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of rock mechanical property testing equipment, and specifically relates to a triaxial pressure chamber for rock testing. Background Art

[0002] The more common rock high-pressure triaxial pressure chamber currently adopts a self-reaction self-balanced pressure chamber, that is, the pressure of the sample confining pressure on the pressure chamber base and the pressure cylinder is borne by the pressure chamber itself, and the confining pressure has no external force on the external loading frame. The pressure of the confining pressure on the piston is usually offset by a balanced piston structure, thereby eliminating the reaction force of the confining pressure on the loading cylinder. The load sensor is usually placed externally on the upper part of the balanced piston.

[0003] The main function of this self-reaction self-balancing pressure chamber is to serve as a high-pressure chamber for samples to complete rock triaxial tests and seepage and other related tests. Since the self-reaction structure requires the pressure tube to be connected to the base, the connection method is usually a buckle type ( Figure 1 ) and bolt-on type ( Figure 2 ).like Figure 1-2 As shown, its main structure includes a load sensor (external), a balance piston, an end cover, a pressure cylinder, an upper pressure head, a lower pressure head, a locking ring and a protective cover (only buckled type), a base, etc.

[0004] The balancing piston is installed on the pressure cylinder through the end cover, penetrates the pressure cylinder and can move up and down in it. The seals between the end cover and the balancing piston, and between the balancing piston and the pressure cylinder are designed to prevent the leakage of the surrounding pressure medium. The load sensor is fixed on the balancing piston or the loading cylinder piston to measure the axial load of the sample. The pressure cylinder is installed on the base through a locking ring or bolts. The lower pressure head below the sample is connected to the base, and the upper pressure head at the upper end cooperates with the balancing piston. When the external axial loading cylinder piston pushes the balancing piston to contact the lower pressure head, the sample begins to bear the axial load.

[0005] For the structural form that uses a locking ring to buckle the pressure cylinder and the base, since the locking ring only bears axial force but not radial force, in order to prevent the pressure cylinder from deforming to form a radial component force that causes the locking ring to fly out, a protective cover is also required to radially limit the locking ring.

[0006] The technical problems existing in the triaxial pressure chamber for the above rock test are as follows:

[0007] 1. The locking ring buckle installation structure has complicated operation steps, difficult operation, and high labor intensity for operators;

[0008] 2. Bolt-fastened installation structure: Since there are many bolts and the bolts are required to be evenly stressed, the operator's labor intensity is high and the test preparation time is long. Summary of the invention

[0009] The purpose of the present invention is to provide a rock testing triaxial pressure chamber to solve the problem of low test efficiency of existing buckle-type and bolt-fastened triaxial pressure chambers. The triaxial pressure chamber uses an axially liftable pressure-bearing cylinder to form a sample test chamber, thereby significantly improving the test efficiency.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A triaxial pressure chamber for rock testing includes a pressure transmission cylinder and a base, wherein the top of the pressure transmission cylinder is used to be interconnected with the top of a loading frame, and the bottom of the base is used to be interconnected with the bottom of the loading frame, and the base and the pressure transmission cylinder are coaxially arranged; a hollow portion for accommodating a loading cylinder piston is arranged inside the pressure transmission cylinder, and a space for placing a sample is reserved between the base and the pressure transmission cylinder; and a pressure bearing cylinder is also included, wherein the upper part of the pressure bearing cylinder is sleeved on the pressure transmission cylinder, and the lower part is sleeved on the base, forming a test chamber for placing the sample, and the pressure bearing cylinder is slidably connected with the pressure transmission cylinder and the base to open or close the test chamber. The pressure chamber or test chamber of this scheme acts on the bottom of the loading frame through the base below, and acts on the top of the loading frame through the bearing cylinder above, and the bearing cylinder is sleeved on the base and the pressure transmission cylinder, so that in the vertical axial direction, the pressure indirectly acts on the loading frame, and in the horizontal direction, the pressure directly acts on the bearing cylinder, without the need for additional connection structures such as buckling or bolting. In addition, the pressure-bearing cylinder is designed to slide up and down along the axis, which makes the placement and removal of the sample very convenient and greatly improves the test efficiency.

[0012] As a preferred solution, a balancing cylinder is provided below the pressure transmission cylinder, and a balancing piston is provided below the loading cylinder piston. The internal cavity of the balancing cylinder introduces confining pressure to make the force on the lower end face of the balancing piston consistent with the force on the upper step, thereby offsetting the reaction force on the external loading cylinder.

[0013] As a preferred solution, the load sensor is built into the pressure chamber and installed below the balancing piston. The built-in load sensor allows the load measurement to be performed directly on the specimen, thereby avoiding other errors and making the measurement data more accurate.

[0014] As a preferred solution, an upper pressure head is connected above the sample, and a lower pressure head is connected below the sample, and the lower pressure head is fixed on the base. This solution provides a solution for fixing the sample in the test, so that the sample is firmly fixed.

[0015] As a preferred solution, a sealing structure is provided between the pressure-bearing cylinder and the base, and between the pressure-bearing cylinder and the pressure-transmitting cylinder. The sealing structure of this solution ensures that the surrounding pressure of the pressure chamber does not leak out.

[0016] As a preferred solution, the pressure-bearing cylinder is positioned with the base and the pressure-transmitting cylinder by means of a stop structure. This solution provides a positioning solution, thereby ensuring accurate positioning of the pressure-bearing cylinder.

[0017] As a preferred solution, a pressure injection hole connected to the confining pressure and back pressure loading system is provided on the base. According to the test requirements for confining pressure and back pressure, this solution provides a pressure injection hole connected to the confining pressure and back pressure loading system on the base of the pressure chamber, thereby providing confining pressure and back pressure for the pressure chamber.

[0018] In summary, due to the adoption of the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. Before the test, you only need to lower the pressure chamber pressure cylinder to the pressure chamber base, and lower the loading cylinder piston until the pressure chamber piston contacts the sample to start the test. The test preparation time is short.

[0020] Second, the pressure chamber has a non-self-reaction structure, which is simple in structure and has a high safety factor. It does not need to buckle and connect the outer cylinder and the base with bolts. It can be operated quickly with one button, which is simple and fast.

[0021] 3. The stroke of the loading cylinder is determined according to the deformation of the specimen, and there is no need to reserve space for the outer cylinder to lift the height. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an existing buckle-type pressure chamber.

[0023] Figure 2 It is a structural schematic diagram of an existing bolt-fastened pressure chamber.

[0024] Figure 3 It is a schematic structural diagram of an embodiment.

[0025] Figure 4 The structure of the embodiment and the test system is shown in FIG. Figure 1 .

[0026] Figure 5 The structure of the embodiment and the test system is shown in FIG. Figure 1 .

[0027] The corresponding marks of the components in the accompanying drawings are: 1-loading cylinder, 2-upper beam of loading frame, 3-pressure transmission cylinder, 4-piston, 5-load sensor, 6-pressure bearing cylinder, 7-base, 8-lower beam of loading frame, 9-hoisting mechanism, 10 trolley mechanism, 11-base, 12-balancing cylinder, 13-balancing piston, 14-load sensor, 15-upper pressure head, 16-sample, 17-lower pressure head. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Example 1

[0030] This embodiment discloses a triaxial pressure chamber for rock testing, which is a key tool for completing triaxial and related tests of rock. The basic functions of the high-pressure triaxial pressure chamber for rock testing include uniaxial compression full stress strain test / dynamic cycle test, triaxial compression full stress strain test / dynamic cycle test, hydraulic fracturing test, seepage test, triaxial high and low temperature test, etc.

[0031] like Figure 3-5 As shown, this embodiment includes a pressure transmission cylinder and a base, the top of the pressure transmission cylinder is used to be interconnected with the top of the loading frame, the bottom of the base is used to be interconnected with the bottom of the loading frame, and the base and the pressure transmission cylinder are coaxially arranged to transmit the axial force generated by the confining pressure to the external loading frame; a hollow portion for accommodating the loading cylinder piston is arranged inside the pressure transmission cylinder, and a gap for placing a sample is reserved between the base and the pressure transmission cylinder; it also includes a pressure-bearing cylinder, the upper part of the pressure-bearing cylinder is sleeved on the pressure transmission cylinder, and the lower part is sleeved on the base to form a test chamber for placing the sample, and the pressure-bearing cylinder is slidably connected to the pressure transmission cylinder and the base to open or close the test chamber.

[0032] In this device, except for the pressure-bearing cylinder that can move up and down along the axis and the external loading cylinder that moves up and down, all other parts are fixed in position. This device adopts a non-self-reacting self-balancing structure. The pressure-bearing cylinder only bears radial pressure, and the axial force generated by the confining pressure on the device is borne by the external loading frame.

[0033] The pressure chamber adopts a column piston type structure. There is no need to connect the bearing cylinder and the base together. The pressure of the confining pressure on the upper and lower parts is transmitted to the loading frame by the pressure transmission cylinder and the pressure chamber base respectively. When the pressure chamber pressure cylinder is lifted to a certain height, the sample can be installed and removed. When the pressure chamber pressure cylinder drops to the pressure chamber base, the test can be started. Based on this scheme, before the test, it is only necessary to lower the pressure chamber pressure cylinder to the pressure chamber base, and the loading cylinder piston drops until the pressure chamber piston contacts the sample to start the test, and the test preparation time is short. In addition, compared with the traditional pressure chamber that needs to be buckled and protected, the test preparation time is long, and the test efficiency is low, the pressure chamber of this scheme is a non-self-reaction force structure with a simple structure and a high safety factor, and there is no need to buckle the pressure cylinder and the base or connect them with bolts.

[0034] This pressure chamber has a quick sealing function. Compared with the traditional method of assembling an independent cover body to the pressure chamber by bolts, it is easy to operate and only requires one person to operate, which significantly improves work efficiency. In addition, in view of the problem that the traditional test system can only perform rock triaxial tests, has a single test function, and has low equipment utilization, this solution has better later scalability.

[0035] The technical effects of this embodiment are as follows:

[0036] 1. Before the test, you only need to lower the pressure chamber pressure cylinder to the pressure chamber base, and lower the loading cylinder piston until the pressure chamber piston contacts the sample to start the test. The test preparation time is short.

[0037] Second, the pressure chamber has a non-self-reaction structure, which is simple in structure and has a high safety factor. It does not need to buckle and connect the outer cylinder and the base with bolts. It can be operated quickly with one button, which is simple and fast.

[0038] 3. The stroke of the loading cylinder is determined according to the deformation of the specimen, and there is no need to reserve space for the outer cylinder to lift the height.

[0039] Example 2

[0040] Based on Example 1, this example is further optimized, specifically including the following aspects. Figure 3 As shown, a balancing cylinder is provided below the pressure transmission cylinder, and a balancing piston is provided below the loading cylinder piston. The internal cavity of the balancing cylinder introduces a confining pressure to make the force on the lower end face of the balancing piston consistent with the force on the upper step, thereby offsetting the reaction force on the external loading cylinder. The balancing piston connected to the load sensor in this device can move up and down under the action of the external loading cylinder, and the other components are fixed in position.

[0041] like Figure 3 As shown, the load sensor is built into the pressure chamber, and the load sensor is installed below the balancing piston. In order to solve the problem that the traditional load sensor is placed outside the pressure chamber, the axial load on the sample is measured with error, and the error is related to the resistance between the balancing piston and the pressure cylinder, the load sensor of this embodiment is built into the pressure chamber, and the axial load on the sample is measured to eliminate the resistance between the piston rod and the piston of the pressure chamber, and the value truly reflects the axial load of the sample.

[0042] like Figure 3 As shown, an upper pressure head is connected above the sample, and a lower pressure head is connected below the sample, and the lower pressure head is fixed on the base.

[0043] In addition, in this embodiment, a sealing structure is provided between the pressure-bearing cylinder and the base, and between the pressure-bearing cylinder and the pressure-transmitting cylinder. The pressure-bearing cylinder is positioned with the base and the pressure-transmitting cylinder (or the balancing cylinder) by a stop structure, and can rise and fall along the axis. The base is provided with a pressure injection hole connected to the surrounding pressure and the counter-pressure loading system. The pressure-bearing cylinder and the base are sealed, the pressure-bearing cylinder and the balancing cylinder are sealed, the balancing cylinder and the balancing piston are sealed, the balancing cylinder and the pressure-transmitting cylinder are sealed, and the pressure-transmitting cylinder and the balancing piston are sealed, so that the surrounding pressure does not leak out.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A triaxial pressure chamber for rock testing, characterized in that: It includes a pressure transmission cylinder and a base, the top of the pressure transmission cylinder is used to be interconnected with the top of the loading frame, the bottom of the base is used to be interconnected with the bottom of the loading frame, and the base and the pressure transmission cylinder are coaxially arranged; a hollow part for accommodating the loading cylinder piston is arranged inside the pressure transmission cylinder, and a gap for placing the sample is reserved between the base and the pressure transmission cylinder; it also includes a pressure-bearing cylinder, the upper part of the pressure-bearing cylinder is sleeved on the pressure transmission cylinder, and the lower part is sleeved on the base, forming a test chamber for placing the sample, and the pressure-bearing cylinder is slidably connected with the pressure transmission cylinder and the base to open or close the test chamber, the pressure-bearing cylinder is positioned with the base and the pressure transmission cylinder by a stop structure, and can rise and fall along the axis; a pressure injection hole connected to the confining pressure and back pressure loading system is arranged on the base.

2. The rock testing triaxial pressure chamber according to claim 1, characterized in that: A balancing cylinder body is arranged below the pressure transmission cylinder, and a balancing piston is arranged below the loading oil cylinder piston.

3. The rock testing triaxial pressure chamber according to claim 2, characterized in that: The load sensor is built into the pressure chamber and is installed below the balancing piston.

4. The rock testing triaxial pressure chamber according to claim 2, characterized in that: An upper pressure head is connected above the sample, and a lower pressure head is connected below the sample, and the lower pressure head is fixed on the base.

5. The rock testing triaxial pressure chamber according to claim 1, characterized in that: A sealing structure is arranged between the pressure-bearing cylinder and the base, and between the pressure-bearing cylinder and the pressure-transmitting cylinder.

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