CN100520345C - True three-dimensional test system for rock-soil mechanical property test - Google Patents

Abstract

A true three-dimensional testing system for testing the mechanical properties of rock and soil, comprising: a test chamber, which is a closed chamber filled with liquid; a loading device, which is arranged inside the test chamber and is used to apply a load to the rock and soil sample clamped by the loading device; a dynamometer, which is arranged inside the test chamber and is used to sense the magnitude of the load applied by the loading device; a displacement sensor, which is arranged outside the test chamber and is used to sense the strain of the rock and soil sample under the action of the load. The loading device is composed of four rigid sliding loading plates overlapped with each other to form a central accommodating space. The loading device also includes four loading pistons acting on the middle position of the sliding loading plate respectively, which are used to apply a load to the sliding loading plate. The sliding loading plates are overlapped in such a way that they can slide relative to each other in the horizontal direction and the vertical direction under the action of the loading pistons.

Description

True 3D Testing System for Rock and Soil Mechanical Performance Testing

technical field

The invention relates to a rock and soil mechanics testing system, which is used for testing the stress-strain strength characteristics of rock and soil samples under the action of three-dimensional stress.

Background technique

In municipal engineering construction, it is of great significance to determine the mechanical properties of rock and soil in advance for the prediction of building settlement, the determination of construction plan, and even the structural form of buildings. Generally speaking, the measurement of the stress-strain strength characteristics of rock and soil generally uses a true three-dimensional system (Truly Triaxial Systems: TTS). As shown in FIG. 1 , a true three-dimensional test means that a brick-shaped (or cube-shaped, with six planes) geotechnical sample 10 is subjected to uniform pressure (and/or strain) in three directions (or three axes). True three-dimensional testing is of great significance for measuring the stress-strain properties of rock and soil under loads in three main directions.

Existing true 3D systems (TTS) can be divided into three types:

1. Use of six rigid sliding loading plates (so-called British Cambridge type). This type of system applies loads on six surfaces of a geotechnical sample through rigid loading plates. However, it has the following disadvantages: although the displacement due to the movement of the loading plate is uniform, the stress and strain experienced by the cubic geotechnical sample are not uniform. Also, it is difficult to measure the water pressure in the soil hole.

2. Using a test chamber with six flexible rubber membranes to apply pressure to the cube-shaped soil sample (mainly used in Japan). This type of system applies loads on six surfaces of a geotechnical sample through a flexible rubber membrane. Its defect is that there is a concentration of stress and strain at the corner, and the stress and strain in the rock and soil are not uniform, and it is also very capable of measuring the water pressure in the rock and soil hole.

3. Use a combination of rigidly loaded plates, semi-rigid plates, and/or flexible plates. But the disadvantage of this system is that it is prone to interference at the corners; the stress and strain are also not uniform.

Contents of the invention

In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a true three-dimensional testing system for testing the mechanical properties of rock and soil, which can make rock and soil samples have uniform stress and strain, and at the same time facilitate the measurement of rock and soil pores water pressure in.

In order to achieve the above object, the present invention provides a true three-dimensional testing system for testing rock and soil mechanical properties, comprising: a testing chamber, which is a closed chamber filled with liquid; a loading device, which is arranged inside the testing chamber , for applying a load to the rock and soil sample clamped by the loading device; a load cell, arranged inside the test chamber, for sensing the magnitude of the load applied by the loading device; a displacement sensor, arranged outside the test chamber , used to sense the strain of the rock-soil sample under the load; wherein, the loading device includes four rigid sliding loading plates, overlapping each other to enclose a central accommodating space, held by the loading device The rock and soil sample is located in the central accommodating space, and one surface of the sliding loading plate is in contact with the rock and soil sample; the loading device also includes four loading pistons respectively acting on the middle positions of the sliding loading plate for The sliding loading plate applies a load to pressurize the rock and soil sample; and the loading piston is fixed with a sliding block (305, 306, 307 and 308) that can slide on the other surface of the sliding loading plate , the sliding block and the corresponding sliding loading plate can slide along the strain direction of the rock-soil sample, and after the rock-soil sample is strained and the sliding loading plate slides, by sliding the sliding block Make it correspond to the central position of the deformed central accommodating space; wherein, the four sliding loading plates are overlapped in such a way that they can slide relative to each other in the horizontal and vertical directions under the action of the loading piston.

The true three-dimensional testing system as described above, wherein a sliding block is arranged between the loading piston and the sliding loading plate, and the sliding block is fixedly connected to the loading piston and is slidably connected to the sliding loading plate, so that the loading piston and the sliding loading plate are slidably connected. The slide loads the slide connection between the plates.

The true three-dimensional testing system as described above, wherein a dovetail-shaped guide groove is formed on the other surface of the sliding loading plate, the sliding block is formed in a wedge shape and has a rolling bearing, and the sliding block is fitted in the guide groove .

The true three-dimensional testing system as described above, wherein a V-shaped groove with a roller bearing is provided on both sides of one end of each sliding loading plate, and a V-shaped fitting is fixedly arranged on the other end on both sides of each sliding loading plate Parts, the V-shaped fitting of one loading plate is slidingly fitted with the V-shaped groove of the other adjacent loading plate.

The true three-dimensional testing system as described above, wherein the rock and soil sample is encapsulated in a flexible rubber film and formed into a cube.

In the true three-dimensional testing system as described above, holes may be respectively opened on the upper and lower parts of both sides of the rubber film encapsulating the rock-soil sample, and plastic hoses are respectively connected to the outside of the testing chamber through the two holes, It is convenient to measure the amount of water drained/into the soil sample or the water pressure in the soil hole.

In the true three-dimensional testing system described above, a threaded hole may be provided at the center of the sliding block, and the loading piston is fixed on the sliding block through the threaded hole.

The true three-dimensional testing system as described above, wherein the pressure sensor is a linear variable differential sensor.

The true three-dimensional testing system as described above, wherein the loading piston can be driven by a hydraulic system, a pneumatic system or an electromagnetic system.

The true three-dimensional testing system as described above, which also includes a computer connected to the testing room, receives the output signals of the dynamometer and the displacement sensor, and calculates and processes them, so as to obtain the mechanical properties of the rock and soil sample. Performance.

The beneficial effect of the present invention is that the test system of the present invention overcomes the defect of only using rigid plates and only flexible films to load stress because it uses four rigid sliding plates and two flexible films to load stress. In addition, by setting a sliding block between the loading piston and the sliding loading plate, the piston can always be located in the central position of the deformed central accommodation space, which can ensure that the load is applied to the central position of the rock and soil sample, ensuring that the rock Uniform distribution of stresses within the soil.

The system of the invention can be used to study the stress-strain characteristics of rock and soil under the state of three-dimensional stress, thereby facilitating municipal engineering construction.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a schematic diagram of a cube-shaped rock-soil sample subjected to axial pressure in three directions;

Fig. 2 is a vertical sectional view showing the structural principle of the true three-dimensional testing system of the present invention;

3 is a structural configuration diagram of sliding plates located in four directions inside the test chamber in the three-dimensional testing system according to an embodiment of the present invention;

Figure 4 is an exploded schematic view showing one of the rigid sliding plates and the wedge-shaped sliding block;

Fig. 5 is a schematic diagram showing the combination of one of the rigid sliding plates and the wedge-shaped sliding block;

Figure 6A is a side view showing one of the rigid slide plates;

Figure 6B is a front view showing one of the rigid slide plates;

Figure 6C is a top view showing one of the rigid slide plates;

7A, 7B and 7C are a front view, a side view and a top view showing the wedge-shaped sliding block, respectively.

Detailed ways

As shown in FIG. 2 , the true three-dimensional measurement system 1 of the present invention is mainly composed of a test room 20 and a computer (not shown) connected to the test room 20 . The test chamber 20 is a sealed rigid test chamber filled with water (or oil) from which air has been removed. The rock and soil sample 10 to be tested is packaged in a cube-shaped rubber film (not shown in the figure), thereby also forming a cube shape, then clamped by the sliding loading device 30 of the present invention, and arranged in the inside of the test chamber . The water (or oil) in the test chamber will exert a sealing pressure on the rock soil sample 10 . As shown in Figure 2, the sliding loading plate device 30 of the present invention is made of rigid sliding loading plates in four directions, including two vertical plates 301, 303 and two horizontal plates 302 and 304, while the remaining two directions are not provided. Instead of a rigid sliding load plate, the flexible film encasing the geotechnical sample applies loads in directions located on both sides perpendicular to the plane of the drawing. Thus, the true three-dimensional measurement system of the present invention is loaded by combining four rigid sliding plates and flexible films.

Fig. 2 exemplarily shows the structure and working principle of the sliding loading device 30 of the present invention. Wherein, four rigid sliding loading plates 301 , 302 , 303 and 304 are overlapped with each other to enclose a central accommodating space for accommodating the rock soil sample 10 . The slide loading device 30 also includes four loading pistons 309 , 310 , 311 and 312 respectively acting on the middle positions of the slide loading plate for applying load to the slide loading plate. The four sliding loading plates 301, 302, 303, and 304 are overlapped in such a way that they can slide against each other horizontally and vertically under the action of the loading piston, so that as the soil sample is loaded After the strain occurs under action, the central accommodating space will also become smaller, so as to ensure that the load is always applied to the rock-soil sample 10 .

In order to ensure that after the sliding loading plates 301, 302, 303 and 304 slide, the loading pistons 309, 310, 311 and 312 still act on the center position of the sliding loading plates, so as to ensure that the stress of the rock and soil sample is uniform, the above loading Slide blocks 305 , 306 , 307 and 308 are arranged between the pistons 309 , 310 , 311 and 312 and the slide loading plates 301 , 302 , 303 and 304 respectively. The above-mentioned sliding blocks are respectively fixed with the loading piston, and are slidably connected with the sliding loading plate along the strain direction of the rock-soil sample 10 . In this way, after the rock-soil sample is strained and the sliding loading plate slides, by sliding the sliding block to make it located in the central position of the deformed central accommodating space, it can be ensured that the load is applied to the central position of the rock-soil sample 10, ensuring Uniform distribution of internal stress in the rock.

The loading piston in the present invention can be driven by a hydraulic system, or by a pneumatic system or an electromagnetic system.

In order to measure the load applied by each loading piston 309, 310, 311 and 312 to each sliding loading plate 301, 302, 303 and 304, three load cells (Loadcell) 313, 314 and 315 are also arranged inside the test chamber 20. , two of which are horizontal and one vertical.

In addition, in order to measure the strain of the soil sample 10 under load, the top piston 310 has a linear variable differential transducer (LVDT) (not shown in the figure) for measuring the displacement in the vertical direction. The bottom piston 312 is fixed. The two horizontal pistons 309, 311 are used to apply pressure in the horizontal direction, and also each have a linear variable differential transducer (LVDT) (not shown) for measuring the displacement in the horizontal direction. The signals from the force gauge and the differential sensor are transmitted to the computer connected to the testing room 20 for subsequent analysis and calculation.

For specific testing schemes, the testing system of the present invention can be adjusted appropriately. For example, holes 41, 42 can be respectively provided on the upper and lower sides of the rubber film of the closed rock and soil sample 10, and plastic hoses 43, 44 are connected to the test chamber 20 from the two holes 41, 42 respectively. external. The plastic hoses 43, 44 can be used to measure drainage in a drained shear test, or to measure water pressure in an undrained test.

By measuring the volume change of the liquid inside the test chamber 20 and the vertical and horizontal displacement values output by the sensor, the average displacement of the cube-shaped rock-soil sample 10 on the two flexible sides is calculated. The stress-strain strength characteristics of rock and soil samples are thus calculated.

An embodiment of the sliding loading device 30 in the present invention will be discussed in detail below with reference to FIGS. 3 , 4 , 5 , 6A-6C and 7A-7C.

FIG. 3 shows a structural combination diagram of an embodiment of the sliding loading device 30 of the present invention. Figure 4 shows an exploded schematic diagram of the sliding loading plate and the wedge-shaped sliding block. Fig. 5 shows a schematic diagram of the combination of the sliding loading plate and the wedge-shaped sliding block. 6A-6C and 7A-7C are plan views of the slide loading plate and the wedge-shaped slide block, respectively.

As shown in FIG. 2 and FIG. 3 , the sliding loading plates 301 , 302 , 303 and 304 overlap each other in a slidable manner. Specifically, the lower end 3031 of the sliding loading plate 303 is positioned above the upper surface of the loading plate 304 , while the other end 3032 is suspended so that the loading plate 303 can slide along the upper surface of the loading plate 304 . The other loading plates are overlapped successively in the same way.

As shown in Figures 2 and 3, in order to facilitate sliding, a V-shaped groove 50 with a roller bearing is provided at one end on both sides of each loading plate, and a V-shaped groove 50 is fixed at the other end on both sides of each loading plate. As for the fitting 60, it can be seen from FIG. 3 that the V-shaped fitting 60 of one loading plate is slidingly fitted with the V-shaped groove 50 of another adjacent loading plate. The cooperation between the above-mentioned V-shaped fitting and the V-shaped groove defines that the loading plate can only slide in one direction, and at the same time maintains a right angle between two adjacent loading plates, and also reduces the distance between the loading plates. friction.

As shown in Figure 4 and Figure 5, a dovetail-shaped guide groove 70 is formed on one surface of each rigid sliding loading plate, and wedge-shaped sliding blocks 305, 306, 307 and 308 are respectively arranged in the guide groove of each loading plate . The above-mentioned wedge sliders also each have a roller bearing. Therefore, the above-mentioned sliding block can only slide in one direction, and maintain a right angle of 90 degrees between the loading plate and the loading piston, while reducing the sliding friction force.

In order to facilitate the connection between the sliding block and the loading piston, a threaded hole 80 may be provided at the central position of the sliding block.

The test system of the present invention overcomes the defect of only using rigid plates and flexible films for loading because it uses four rigid sliding loading plates and two flexible films to load stress. Since the sliding blocks are respectively consolidated with the loading piston, and are slidingly connected with the sliding loading plate along the strain direction of the rock-soil sample, in this way, after the rock-soil sample is strained and the sliding loading plate slides, by sliding the sliding block to make it Located in the central position of the deformed central accommodation space, it can ensure that the load is applied to the central position of the rock and soil sample, ensuring the uniform distribution of the internal stress of the rock and soil.

The system of the invention can be used to study the stress-strain characteristics of rock and soil under the state of three-dimensional stress, thereby facilitating municipal engineering construction.

The above describes the present invention by way of example only, but the present invention is not limited thereto, for example, any connection structure that can realize sliding of the sliding block on the loading plate can be used in the present invention. Accordingly, the protection scope of the present invention is determined by the appended claims.

Claims (6)

1. A true three-dimensional testing system for testing rock and soil mechanical properties, including: A test chamber (20), which is a closed chamber filled with liquid; A loading device (30), which is arranged inside the test chamber, is used to apply a load to the rock and soil sample (10) clamped by the loading device; Dynamometers (313, 314 and 315) are arranged inside the test chamber for sensing the magnitude of the load applied by the loading device; displacement sensors are arranged outside the test chamber for sensing the rock soil sample in the strain under load; It is characterized in that the loading device (30) includes four rigid sliding loading plates (301, 302, 303 and 304), which are overlapped with each other to form a central accommodation space, and the rock and soil samples clamped by the loading device Located in the central accommodating space, one surface of the sliding loading plate is in contact with the rock-soil sample; The loading device (30) also includes four loading pistons (309, 310, 311 and 312) respectively acting on the middle positions of the sliding loading plates, for applying loads to the four sliding loading plates, thereby Pressurize the sample; and the loading piston is fixed with sliding blocks (305, 306, 307 and 308) that can slide on the other surface of the sliding loading plate, and the sliding blocks can be connected with the corresponding sliding blocks. The loading plate slides along the strain direction of the rock-soil sample, and after the rock-soil sample is strained and the sliding loading plate slides, slide the sliding block so that it is located in the deformed central accommodation space central location; Wherein, the four sliding loading plates are overlapped in such a way that they can slide relative to each other in the horizontal and vertical directions under the action of the loading piston. 2. The true three-dimensional testing system according to claim 1, wherein a dovetail-shaped guide groove is formed on the other surface of the sliding loading plate, the sliding block is formed in a wedge shape and has a rolling bearing, and the sliding block Fit into the guide groove. 3. The true three-dimensional testing system according to claim 1, characterized in that a V-shaped groove (50) with a roller bearing is provided on one end of each side surface of each sliding loading plate, and on each sliding loading plate The other end of the two side surfaces is fixedly provided with a V-shaped fitting (60), and the V-shaped fitting of one sliding loading plate is slidably matched with the V-shaped groove of the other adjacent sliding loading plate. 4. The true three-dimensional testing system according to claim 3, characterized in that, the V-shaped fitting fits with the V-shaped groove to keep two adjacent sliding loading plates at right angles, so as to reduce the Frictional resistance between two slide-loaded plates. 5. The true three-dimensional testing system according to claim 1, characterized in that the rock and soil sample is packaged in a flexible rubber film and formed into a cube. 6. The true three-dimensional testing system according to claim 5, characterized in that holes (41, 42) are respectively opened on the upper and lower parts of the two sides of the rubber film encapsulating the geotechnical sample (10), and the plastic soft Pipes (43, 44) are respectively connected to the outside of the test chamber (20) from the two holes (41, 42).

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