CN203083892U - Stress-strain control type direct shear apparatus - Google Patents

Abstract

The utility model provides a stress-strain control type direct shear instrument. The direct shear instrument comprises upper and lower shear boxes to form a square shear box for accommodating rock and soil samples. The upper end of the upper shear box is provided with a One end of the lower shear box matches the horizontal shear loading mechanism used for stress-controlled direct shear tests, and the other end matches the horizontal shear loading mechanism used for strain-controlled direct shear tests. The horizontal load mechanism is matched, and the horizontal load mechanism includes a torque conversion box arranged on the test platform and a horizontal load tension pressure sensor connected to the torque conversion box and the lower shear box respectively. The direct shear instrument described in the utility model can be Strain-controlled direct shear test and stress-controlled direct shear test can be carried out, the structure is simple, the processing cost is low, and it is easy to popularize and apply in production and teaching.

Description

Stress-strain controlled direct shear instrument

technical field

The utility model belongs to the field of geotechnical engineering, in particular to a direct shear instrument, in particular to a stress-strain control multifunctional direct shear instrument.

Background technique

The direct shear instrument is the most conventional test equipment in geotechnical tests, and it is mainly used to measure the shear strength parameters of rock and soil under static load conditions. Most of the instability of rock and soil is caused by shear failure, and the instability and damage of geotechnical engineering are accompanied by the development of shear displacement. It is of great significance in the construction of geotechnical engineering to accurately measure the shear strength parameters of rock and soil, and the direct shear test is an important test method.

The direct shear test is the earliest and most direct test method for determining the shear strength of rock and soil developed on the basis of Coulomb's theory. The test can be divided into two types: stress control type and strain control type. The stress control type direct shear test is to put the soil sample into the shear box, apply a vertical pressure to the soil sample through the pressure plate, and apply a constant force to the sample. The horizontal shear force is used to measure the corresponding shear displacement, which is used in the creep test to determine the long-term strength of the soil; the strain-controlled direct shear test is to shear the soil sample at a constant rate while applying vertical pressure to measure its The corresponding horizontal shear stress is used to determine the normal shear strength of soil.

At present, one of the common direct shear instruments at home and abroad is the single-box direct shear instrument, and the other is the quadruple shear instrument. The vertical load of the two direct shear instruments both uses a lever mechanism. During the test, it was found that the lever tilted to a large extent after the weight was applied, and the greater the applied load, the greater the inclination angle, reaching a maximum of 30°, which greatly reduced the actual pressure acting on the sample. It can be seen that using the lever The loss of the loading force of the mechanism is relatively large. In addition, the shear box has a single specification, especially the circular shear box used in China, which is small in size and the stress concentration phenomenon is serious, so that the sample has been in a state of uneven stress distribution throughout the test process. With the generation of shear displacement, the inhomogeneity of stress distribution will increase, which will affect the test results.

Utility model content

The purpose of the utility model is to provide a stress-strain control type direct shear instrument.

The direct shear instrument includes a test platform and a lower shear box arranged on the test platform, an upper shear box is arranged on the lower shear box, and the upper and lower shear boxes form a square shear box for accommodating rock and soil samples. The upper shear box is provided with a vertical pressure loading mechanism for applying vertical loads to rock and soil samples, one end of the lower shear box is matched with the horizontal shear loading mechanism for stress-controlled direct shear tests, and the other One end is matched with the horizontal load mechanism used for the strain-controlled direct shear test. The horizontal load mechanism includes a torque conversion box arranged on the test platform and a horizontal load tension pressure sensor connected to the torque conversion box and the lower shear box respectively. , the torque conversion box includes a rack, a gear, a worm gear coaxially connected with the gear, and a worm matched with the worm gear. One end of the rack is matched with the gear, and the other end is connected with the lower shear box. The cutting servo motor.

The direct shear instrument also includes a support frame and a beam connected with the support frame, and the test platform is arranged on the support frame.

The bottom two edges of the upper shear box are provided with the lower V-shaped grooves of the upper shear box consistent with the shear displacement direction, and the upper two edges of the lower shear box are provided with lower V-shaped grooves corresponding to the lower V-shaped grooves of the upper shear box. The V-shaped groove on the shear box, the V-shaped groove of the test platform that is consistent with the shear displacement direction is set on the test platform, and the lower V-shaped groove of the lower shear box that matches the V-shaped groove of the test platform is arranged on both sides of the bottom of the lower shear box. Groove.

There are more than two V-shaped grooves on the test platform.

The lower shear box includes a water storage box and an inner box fixed at one end of the water storage box. The V-shaped groove on the lower shear box is arranged on the upper edge of the inner box, and the height of the water storage box is greater than that of the inner box.

The vertical pressure loading mechanism includes a pressure cover opposite to the upper shear box, the upper end of the pressure cover is connected with the lower end of the vertical load tension pressure sensor, the upper end of the vertical load tension pressure sensor is connected with the upper end of the vertical load pressure cross bar The lower end of the vertical load press bar is connected with the vertical load pulley block set at the lower end of the test platform. The fixed pulley block of the vertical pressure loading mechanism is connected with the moving pulley block of the loading mechanism, and the vertical loading pulley block is connected with the vertical loading weight arranged at the lower end of the test platform.

The moving pulley block of the vertical pressure loading mechanism and the vertical load pressing cross bar adopt a point connection mode.

The horizontal shear loading mechanism includes a shear loading pulley set arranged at the lower end of the test platform and a horizontal loading weight connected to the shear loading pulley. The shear loading pulley includes a horizontal shear connecting to the lower shear box. The moving pulley block of the force loading mechanism and the fixed pulley block of the horizontal shearing force loading mechanism connected with the moving pulley block of the horizontal shearing force loading mechanism.

The direct shear instrument also includes a strain control electronic screen arranged on the test platform, the vertical load tension sensor and the horizontal load tension pressure sensor are respectively connected with the strain control electronic screen, and the strain control electronic screen is connected with the shear servo motor.

There are multiple sets of torque conversion boxes, and disengageable bearings for connecting adjacent worms are arranged between the torque conversion boxes.

The beneficial effects of the utility model are embodied in that the direct shear instrument described in the utility model is a multifunctional direct shear instrument, and the strain-controlled direct shear can be performed on one instrument by setting a horizontal load mechanism and a horizontal shear force loading mechanism. Shear test and stress-controlled direct shear test can also be carried out; all parts in the direct shear instrument described in the utility model are mechanically connected, with simple structure, low processing cost, convenient use, and particularly convenient maintenance and replacement of parts. Saving the cost of use provides convenience, and it is easy to popularize and apply in production and teaching.

The direct shear instrument described in the utility model can choose square shear boxes of different sizes for testing by setting up multiple V-shaped grooves of the test platform, and by using a square shear box with a larger size, it is very good to improve the shear capacity of small samples. The problem of shear stress concentration and uneven stress distribution, the measured test data can more truly reflect the shear strength of the soil sample; at the same time, it is also possible to carry out shear tests on multiple (such as two) samples under the same pressure, effectively It eliminates the error caused by the different instruments to the test results.

The lower shear box of the direct shear instrument described in the utility model includes a water storage box, which can be used as a water tank, which ensures that the shear surface of the saturated sample maintains a saturated state during the shear process, and effectively prevents the water from evaporating and the sample from becoming saturated. Increased shear strength due to dryness.

The vertical pressure loading system and the horizontal shear force loading system in the direct shear instrument of the utility model abandon the existing lever loading mechanism, and adopt a pulley block mechanism with more reliable working performance to apply the load, and are equipped with an S-type tension pressure sensor. The real pressure and shear force acting on the sample can be measured, effectively eliminating the loading loss caused by the tilt of the lever. Moreover, the principle of the pulley block mechanism is simple, and the structure is more flexible. During the test, the magnification can be selected according to the requirements, and it is easier to meet different engineering requirements.

The direct shear instrument described in the utility model adopts a servo motor to provide different shearing speeds, and introduces a strain control electronic screen to make the test operation more convenient. The torque conversion box is selected according to the requirements, and the unused shearing unit can stop working by disengaging the connection of the bearing, which minimizes the wear of the instrument.

Description of drawings

Fig. 1 is the structural representation of the stress-strain control type direct shear instrument described in the utility model;

Fig. 2 is the assembly diagram of the square shear box described in the utility model;

Fig. 3 is a detailed view of the lower shear box described in the utility model;

Fig. 4 is the connection diagram of the moving pulley block of the vertical pressure loading mechanism described in the utility model and the vertical load pressurizing cross bar;

Fig. 5 is a connection structure diagram of the detachable bearing of the utility model;

In the figure: 1-support frame; 2-beam; 3-test platform; 4-first fixed pulley, 5-second fixed pulley; 6-third fixed pulley; 7-first test platform V-shaped groove; 8- V-shaped groove of the second test platform; 9-V-shaped groove of the third test platform; 10-V-shaped groove of the fourth test platform; 11-V-shaped groove of the fifth test platform; 12-V-shaped groove of the sixth test platform; 13- Lower shear box; 14-upper shear box; 15-pressure cover; 16-vertical load tension pressure sensor; 17-vertical load pressurization bar; 18-first torque conversion box; 19-second torque conversion box ; 20-strain control electronic screen; 21-the third torque conversion box; 22-shear servo motor; 23-horizontal load tension pressure sensor; 24-moving pulley block of vertical pressure loading mechanism; ; 26-vertical loading weight; 27-horizontal loading weight; 28-fixed pulley block of horizontal shear loading mechanism; 29-moving pulley block of horizontal shear loading mechanism; 30-inner box; 31-water storage box; 32-pin; 33-disconnectable bearing.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Referring to Fig. 1-Fig. 3, this direct shear instrument comprises test platform 3 and is arranged on the lower shear box 13 on test platform 3, is provided with upper shear box 14 on the lower shear box 13, upper and lower shear box forms A square shear box for accommodating rock and soil samples; the bottom two edges of the upper shear box 14 are provided with V-shaped grooves on the bottom of the upper shear box consistent with the shear displacement direction, and the upper two edges of the lower shear box 13 are The upper V-shaped groove of the lower shear box corresponding to the lower V-shaped groove of the upper shear box is provided. The test platform 3 is provided with a V-shaped groove of the test platform consistent with the shear displacement direction. The bottom two edges of the lower shear box 13 The lower V-shaped groove of the lower shear box matched with the V-shaped groove of the test platform is provided with more than two V-shaped grooves of the test platform; the lower shear box 13 includes a water storage box 31 and is fixed to the water storage box 31. In the inner box 30 at one end, the V-shaped groove on the lower shear box is arranged on the upper edge of the inner box 30, and the height of the water storage box 31 is greater than the inner box 30; A vertical pressure loading mechanism for applying a vertical load, one end of the lower shear box 13 is matched with the horizontal shear loading mechanism for the stress-controlled direct shear test, and the other end is matched with the horizontal load for the strain-controlled direct shear test. Mechanism is matched, and described horizontal load mechanism comprises the torque conversion box that is arranged on the test platform 3 and the horizontal load tension pressure sensor 23 that links to each other with torque conversion box and lower shear box respectively, and torque conversion box includes rack, gear, and The worm gear connected coaxially with the gear and the worm screw matched with the worm gear, one end of the rack is matched with the gear, and the other end is connected with the lower shear box. The test platform 3 is provided with a shear servo motor 22 for driving the worm screw. The power of the motor is converted into the linear motion of the lower shear box through the worm gear assembly and the rack and pinion assembly; the direct shear instrument also includes a support frame 1 and a beam 2 connected to the support frame 1, and the test platform 3 is arranged on the support frame 1 superior.

Described vertical pressure loading mechanism comprises the relative pressure cover 15 with upper shear box 14, and the upper end of pressure cover 15 links to each other with the lower end of vertical load tension pressure sensor 16, and the upper end of vertical load tension pressure sensor 16 is connected with vertical load pressure sensor 16. The upper end of the pressing cross bar 17 is connected, and the lower end of the vertical load pressing cross bar 17 is connected with the vertical loading pulley block arranged at the lower end of the test platform 3. Loading mechanism moving pulley block 24 and the vertical pressure loading mechanism fixed pulley block 25 that links to each other with vertical pressure loading mechanism moving pulley block 24, vertical loading pulley block links to each other with the vertical loading weight 26 that is arranged on the lower end of test platform 3; The moving pulley block 24 of the pressure loading mechanism and the vertical load pressing cross bar 17 adopt a point connection mode (referring to FIG. 4 ).

The horizontal shear loading mechanism includes a shear loading pulley set arranged on the lower end of the test platform 3 and a horizontal loading weight 27 connected with the shear loading pulley. The shear loading pulley includes a shear loading pulley connected to the lower shear box 13 Horizontal shear force loading mechanism moving pulley block 29 and the horizontal shear force loading mechanism fixed pulley block 28 linking to each other with horizontal shear force loading mechanism moving pulley block 29; Described direct shear instrument also includes the strain control electronics that is arranged on the test platform 3 The screen 20, the vertical load tension sensor 16 and the horizontal load tension pressure sensor 23 are respectively connected with the signal acquisition card in the strain control electronic screen 20 to complete signal transmission, and complete data processing and display through the built-in data processing software. The strain control electronic screen 20 is connected with the shearing servo motor 22; the torque conversion boxes are in multiple groups, and the disengageable bearings 33 for connecting adjacent worms are arranged between the torque conversion boxes (see FIG. 5 ).

working principle

Before the test, first place the shear box on the corresponding V-shaped groove of the test platform according to the requirements, and then put the prepared sample into the square shear box. The contact edges of the upper and lower shear boxes are aligned with the shear displacement direction The two consistent sides are provided with V-shaped grooves, and balls are installed in the grooves. After the sample loading is completed, the vertical load is applied to the sample. Firstly, the pressure cover is aligned and placed on the sample, and the vertical load pressure bar 17 is aligned and placed on the pressure cover 15. The force transmission device is installed, and the pressure loading is mainly completed by the pulley block, that is, vertical pressure loading Mechanism moving pulley block 24 and vertical pressure loading mechanism fixed pulley block 25. After the vertical pressure is completed, if the stress-controlled direct shear test is carried out, the principle of the vertical pressure system is the same, and the pulley block mechanism is also used to amplify the gravity of the weight several times, and then apply it to the lower shear box to record the shear. The shear displacement of the box under the action of each level of horizontal shear force until the soil sample reaches shear failure. If the strain control type direct shear test is carried out, open the strain control electronic screen 20, select the required shearing speed on the screen and click start, the shearing servo motor drives the worm to rotate, and the power is transmitted to the worm coaxial with the worm through the worm gear. The gear in the connected rack and pinion assembly, the gear and the rack are meshed to push the lower shear box, and the readings measured by the horizontal load tension pressure sensor 23 are recorded, and the test ends after the soil sample is sheared and damaged.

Example

A stress-strain control multifunctional direct shear instrument is mainly composed of a test bench, a strain control system, a vertical pressure loading system, a horizontal shear loading system and a measurement system. As shown in Figure 1, it includes support frame 1, which is used to support the test bench and keep the stability of the whole instrument; beam 2, which mainly plays a role of reinforcement, and provides an installation position for the fixed pulley in the pulley block loading system; The installation of cutting box and the carrying out of test provide platform; The first fixed pulley 4, the second fixed pulley 5 and the third fixed pulley 6 are used to change the direction of shear force, wherein the first fixed pulley 4 and the third fixed pulley 6 are used for 10cm×10cm square shear box, the second fixed pulley 5 is used for 20cm×20cm square shear box; the first test platform V-shaped groove 7, the second test platform V-shaped groove 8, the third test platform V-shaped groove 9. The V-shaped groove 10 of the fourth test platform, the V-shaped groove 11 of the fifth test platform and the V-shaped groove 12 of the sixth test platform are used to place the shear box, and balls are placed in the groove during the test, which not only acts as a guide rail, The friction between the lower shear box and the test platform is also reduced, wherein the first test platform V-shaped groove 7, the third test platform V-shaped groove 9, the fourth test platform V-shaped groove 10, and the sixth test platform V-shaped groove 12 For a square shear box of 10cm×10cm, the second test platform V-shaped groove 8, the fifth test platform V-shaped groove 11 is used for a square shear box of 20cm×20cm; the lower shear box 13 and the upper shear box 14 , used to install the sample; the pressure cover 15 is used to transmit the vertical pressure to the sample; the vertical load tension sensor 16 is used to measure the actual vertical pressure acting on the sample during the test; the vertical load pressurizes the bar 17. The cross bar here mainly transmits the amplified vertical pressure of the pulley block to the pressure cover; the first torque conversion box 18, the second torque conversion box 19 and the third torque conversion box 21 have built-in worm and gear mechanisms for The rotational speed output by the shearing servo motor 22 changes direction and is transmitted to the lower shear box, wherein the first torque conversion box 18 and the third torque conversion box 21 are used for the square shear box of 10cm * 10cm, and the second torque conversion box 19 is used In the square shearing box of 20cm * 20cm; Strain control electronic screen 20, can set shearing speed and shearing displacement on this electronic screen when carrying out test; Cutting servo motor 22, provide power source for the system, control shearing Velocity; Horizontal load tension sensor 23, is used to measure the shear force that acts on sample in the test process; Vertical pressure loading mechanism moving pulley block 24 and vertical pressure loading mechanism fixed pulley block 25 have jointly formed vertical pressure loading system, can The gravity of the vertical loading weight 26 is amplified by five to fifteen times; the fixed pulley block 28 of the horizontal shear loading mechanism and the moving pulley block 29 of the horizontal shear loading mechanism jointly form a shear loading system, and the horizontal loading weight can be The gravity of yard 27 is magnified five times.

The instrument can use the undisturbed soil samples and remodeled soil samples taken from the field to carry out stress-controlled direct shear tests and strain-controlled direct shear tests, and before the test, a 10cm×10cm or 20cm×20cm can be selected according to the test design requirements. The square shear box is used for the test, and two 10cm×10cm square shear boxes can also be selected for parallel pressure tests at the same level in order to obtain more accurate test data.

Before the test, first place the shear box according to the requirements. If a 10cm×10cm square shear box is selected for the test, it can be placed in the V-shaped groove 7 of the first test platform and the V-shaped groove 9 of the third test platform; The 20cm square shear box should be placed in the V-shaped groove 8 of the second test platform and the V-shaped groove 11 of the fifth test platform; if two 10cm×10cm square shear boxes are selected, they should be placed in the first test platform of the groove In the V-shaped groove 7, the third test platform V-shaped groove 9, the fourth test platform V-shaped groove 10, and the sixth test platform V-shaped groove 12, each groove is equipped with balls, and then the prepared sample is loaded in a square cutout box. The square shearing box is composed of a lower shearing box 13 and an upper shearing box 14. Among the contact edges of the upper and lower shearing boxes, the two sides that are consistent with the direction of shear displacement are provided with V-shaped grooves, and balls are installed in the grooves. , the square shear box assembly is shown in Figure 2. For the lower shear box 13, a rectangular stainless steel box was added outside the single shear box. This stainless steel box is about 1 cm higher than the inner shear box. It is mainly used for adding water when measuring the shear strength parameters of saturated soil samples. , keep the water content of the soil sample on the shear plane between the upper and lower shear boxes, so that the measured result is the true shear strength of the saturated soil sample. Considering that the upper and lower shear boxes will produce a relative displacement during the shearing process, the stainless steel box set outside the lower shear box has a distance between the side opposite to the shear displacement direction and the same side of the lower shear box. The distance is relatively large, about twice the general shear failure displacement, and the details of the lower shear box are shown in Fig. 3.

After the sample loading is completed, the vertical load is applied to the sample. The application of the vertical load mainly involves the pressure cover 15, the vertical load tension pressure sensor 16, the vertical load pressure bar 17, the vertical pressure loading mechanism moving pulley block 24, the vertical pressure loading mechanism fixed pulley block 25 and the vertical loading weight 26 . Firstly, place the pressure cover 15 on the sample in an aligned manner, and do not contact with the wall of the square shear box. The vertical load tension pressure sensor 16 is integrated with the vertical load pressure bar 17, and the vertical load pressure bar 17 is aligned. Place it on the pressure cover 15, the force transmission device is installed, and then the loading device is installed. The loading of pressure is mainly completed by the pulley block, that is, the moving pulley block 24 of the vertical pressure loading mechanism and the fixed pulley block 25 of the vertical pressure loading mechanism. Different from the traditional pulley block mechanism, the utility model puts the movable pulley on the fixed pulley, which can make the applied load doubled, and considering the convenience of the test operation, the vertical pressure loading mechanism movable pulley block 24 and the vertical load press horizontal The rod 17 adopts a point connection method, as shown in FIG. 4 , this design is conducive to the balance of the vertical load pressurizing the cross rod 17 . Compared with the loading of the lever mechanism, the loading of the pulley block is more reliable, and the magnification of the force can be adjusted according to the demand, so it has better flexibility.

After the vertical pressurization is completed, if the stress-controlled direct shear test is carried out, the horizontal shear loading system will be used next, involving the horizontal loading weight 27, the fixed pulley block 28 of the horizontal shear loading mechanism and the horizontal shear loading system. Loading mechanism moving pulley block 29. Similar to the principle of the vertical pressurization system, the horizontal shear load system also uses a pulley block mechanism to amplify the gravity of the weight several times, and then applies it to the lower shear box. At the same time, a dial indicator is equipped to record the shear displacement of the shear box under the action of each level of horizontal shear until the soil sample reaches shear failure.

After the vertical pressurization is completed, if the strain-controlled direct shear test is carried out, the strain control system is used, involving the first torque conversion box 18, the second torque conversion box 19, the third torque conversion box 21, Strain control electronic screen 20, shear servo motor 22, horizontal load tension pressure sensor 23. When carrying out the test, it is only necessary to turn on the strain control electronic screen 20 after connecting the power supply, select the required shearing speed on the screen, and then click start. Here, the connection between the first torque conversion box 18, the second torque conversion box 19 and the third torque conversion box 21 has selected a disengageable bearing connection, and the torque conversion box can be connected or separated according to the requirements during the test. The connection structure As shown in Figure 5. Simultaneously, the readings measured by the horizontal load tension pressure sensor 23 are recorded, and the test ends after the shear failure of the soil sample occurs.

Claims (10)

1. A stress-strain control type direct shear instrument is characterized in that: this direct shear instrument comprises a test platform (3) and a lower shear box (13) arranged on the test platform (3), a lower shear box (13) ) is provided with an upper shearing box (14), the upper and lower shearing boxes form a square shearing box for containing rock and soil samples, and the upper shearing box (14) is provided with a The vertical pressure loading mechanism of the load, one end of the lower shear box (13) cooperates with the horizontal shear loading mechanism, and the other end cooperates with the horizontal loading mechanism, and the horizontal loading mechanism includes The torque conversion box and the horizontal load tension pressure sensor (23) respectively connected with the torque conversion box and the lower shear box (13), the torque conversion box includes a rack, a gear, a worm gear coaxially connected with the gear, and a As for the worm, one end of the rack is matched with the gear, and the other end is connected with the lower shear box. The test platform (3) is provided with a shearing servo motor (22) for driving the worm. 2. A stress-strain controlled direct shear instrument according to claim 1, characterized in that: the direct shear instrument also includes a support frame (1) and a beam (2) connected to the support frame (1), a test platform (3) Set on the support frame (1). 3. A stress-strain controlled direct shear instrument according to claim 1, characterized in that: the two edges of the bottom of the upper shear box (14) are provided with the lower V of the upper shear box that is consistent with the shear displacement direction. V-shaped grooves on the upper two edges of the lower shear box (13) are provided with V-shaped grooves on the lower shear box corresponding to the lower V-shaped grooves of the upper shear box, and the test platform (3) is provided with The V-shaped groove of the test platform, the bottom two edges of the lower shear box (13) are provided with the lower V-shaped groove of the lower shear box matched with the V-shaped groove of the test platform. 4. A stress-strain control type direct shear instrument according to claim 3, characterized in that: there are more than two V-shaped grooves on the test platform. 5. A stress-strain controlled direct shear instrument according to claim 3, characterized in that: the lower shear box (13) includes a water storage box (31) and a water storage box (31) fixed at one end of the water storage box (31) In the inner box (30), the V-shaped groove on the lower shear box is arranged on the upper edge of the inner box (30), and the height of the water storage box (31) is greater than that of the inner box (30). 6. A stress-strain controlled direct shear instrument according to claim 1, characterized in that: the vertical pressure loading mechanism includes a pressure cover (15) opposite to the upper shear box (14), and the pressure cover The upper end of (15) links to each other with the lower end of the vertical load tension pressure sensor (16), the upper end of the vertical load tension pressure sensor (16) links to each other with the upper end of the vertical load pressurization cross bar (17), and the vertical load pressurization cross bar (17) ) is connected to the vertical loading pulley block arranged at the lower end of the test platform (3), and the vertical loading pulley block includes a vertical pressure loading mechanism moving pulley block (24) connected to the lower end of the vertical load pressing bar (17) and The fixed pulley block (25) of the vertical pressure loading mechanism connected to the moving pulley block (24) of the vertical pressure loading mechanism, and the vertical loading pulley block is connected to the vertical loading weight (26) arranged at the lower end of the test platform. 7 . The stress-strain controlled direct shear instrument according to claim 6 , characterized in that: the moving pulley block ( 24 ) of the vertical pressure loading mechanism and the vertical load pressing crossbar ( 17 ) are connected by points. 8. A stress-strain control type direct shear instrument according to claim 6, characterized in that: the horizontal shear loading mechanism includes a shear loading pulley block arranged at the lower end of the test platform (3) and a The horizontal loading weight (27) connected to the loading pulley block, the shear force loading pulley block includes the horizontal shear force loading mechanism moving pulley block (29) connected with the lower shear box (13) and the horizontal shear force loading mechanism moving pulley block (29) fixed pulley block (28) of the horizontal shear loading mechanism connected. 9. A stress-strain control type direct shear instrument according to claim 8, characterized in that: the direct shear instrument also includes a strain control electronic screen (20) arranged on the test platform (3), vertical load tension pressure The sensor (16) and the horizontal load tension pressure sensor (23) are respectively connected with the strain control electronic screen (20), and the strain control electronic screen (20) is connected with the shearing servo motor (22). 10. A kind of stress-strain control type direct shear instrument according to claim 1, characterized in that: the torque conversion boxes are in multiple groups, and there are disengageable bearings (33 for connecting adjacent worms) between the torque conversion boxes. ).

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