CN110987642A - Rigid-flexible composite true triaxial loading device of rubber film outer wrapping loading plate - Google Patents

Abstract

The invention provides a rigid-flexible composite true triaxial loading device with a rubber film outsourcing a loading plate, comprising: a sliding loading component and a rubber film; the sliding loading component includes four rigid loading plates; the four rigid loading plates are respectively provided with loading Piston, the loading piston applies load to the rigid loading plate; the four rigid loading plates overlap each other in four directions to form a frame with a central accommodating space, and the central accommodating space of the frame is used for accommodating and holding the geotechnical test. The rubber film is wrapped around the frame and the outside of the geotechnical sample, and the flexible film applies load to the geotechnical sample along the direction perpendicular to both sides of the frame. In the invention, the rubber film is arranged outside the rigid loading plate, and the pore water pressure can be directly measured by applying the load through the loading piston connected with the rigid loading plate, and the pressure on the soil sample in this direction during shearing can be less than the surrounding pressure. The water pressure in the pressure chamber can perform any Lode angle test from 0 to 360 degrees.

Description

A rigid-flexible composite true triaxial loading device with a rubber film outer loading plate

technical field

The invention relates to the field of geotechnical mechanics testing, in particular to a rigid-flexible composite true triaxial loading device with a rubber film outer loading plate.

Background technique

Three-dimensional analysis problems are often encountered in geotechnical engineering. The design and experimental study of true triaxial instruments has always been an active and challenging research field. The measurement of the stress-strain strength characteristics of rock and soil generally adopts a true triaxial system. True triaxial testing means that a cube-shaped geotechnical sample is subjected to uniform pressure (or strain) in three directions (or three axes). True triaxial testing is of great significance for measuring the stress-strain behavior of rock and soil under loads in three main directions.

The existing loading devices for true triaxial tests can be divided into the following three types: (1) rigid loading; (2) flexible loading; (3) mixed boundary loading. At present, the most widely used is the hybrid boundary loading method, which solves many limitations in pure rigid and pure flexible loading, but this system also has some defects, such as interference at the corners, if there is a gap between the steel plates There is also the possibility of soil extrusion, stress and strain also being unevenly distributed.

In addition to the above problems, the rubber film used to seal the sample in the existing loading system does not wrap the loading plate, and the loading plate is not directly acting on the geotechnical sample, so the water in the soil hole cannot be directly measured. pressure.

After searching, it is found that the Chinese patent application number 2018116106201 discloses a true triaxial experimental system and method for intelligent identification of bulk material porosity, wherein, as shown in Figure 1, the first mechanical confining pressure loading component includes a first mechanical The confining pressure controller, the first mechanical confining pressure loading rod and the first mechanical confining pressure loading plate; the outer end of the first mechanical confining pressure loading rod is fixedly connected with the end of the piston rod of the first mechanical confining pressure controller, the first mechanical The inner end of the confining pressure loading rod is located inside the pressure chamber; the first mechanical confining pressure loading plate is vertically fixed on the inner end of the first mechanical confining pressure loading rod, and the inner surface of the first mechanical confining pressure loading plate is in contact with the bulk material test .

However, the above-mentioned patents have the following shortcomings: First, the loading method in the above-mentioned patents is non-sliding loading, so there is a gap between the loading plates, and the problems of soil extrusion and uneven stress distribution at the edge of the sample will occur during the loading process. In addition, the pore water pressure in the sample cannot be directly measured during the experiment through the above-mentioned patent, nor can the full Lord angle test be performed.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a rigid-flexible composite true triaxial loading device for testing the mechanical properties of rock and soil.

The invention provides a rigid-flexible composite true triaxial loading device with a rubber film outer loading plate, comprising: a sliding loading part and a rubber film; wherein,

The sliding loading member includes four rigid loading plates; the four rigid loading plates are respectively provided with loading pistons, the outer sides of the rigid loading plates are connected with the loading pistons, and the loading pistons load the rigid loading plates connected thereto. The four rigid loading plates overlap each other in four directions to form a frame with a central accommodating space, and the central accommodating space of the frame is used for accommodating and clamping the geotechnical samples; and The four rigid loading plates can slide relative to each other in the horizontal direction and the vertical direction under the action of each loading piston, so that after the geotechnical sample is strained under the action of the load, the central The accommodating space will also be reduced accordingly to ensure that the load is always applied to the geotechnical sample; the sliding loading component includes four fasteners, and the four fasteners are respectively arranged on each of the On the outer side of the rigid loading plate, a combined loading system is formed between the four rigid loading plates and the four fasteners;

The rubber film is wrapped on the outside of the frame and the geotechnical sample, and is located between the rigid loading plate and the fastener, and the rubber film is clamped by the fastener, so that the to seal the geotechnical specimen,

The flexible film applies a load to the geotechnical sample in a direction perpendicular to both sides of the frame.

Preferably, the sliding loading component further includes four connecting pieces and four sliding blocks;

The four connecting pieces are respectively fixed on the outer sides of the four rigidly loaded plates for transmitting loads to the rigidly loaded plates;

The four sliding blocks are respectively arranged between each rigid loading plate and the loading piston, one end of the sliding block is detachably connected with the connecting piece, and the other end is connected with the loading piston through a detachable connection. The sliding bearing realizes the sliding connection, so that the sliding loading plate can slide freely along the direction perpendicular to the connected loading piston;

It is realized that the four rigid loading plates can slide relative to each other in the horizontal direction and the vertical direction through the four sliding blocks respectively under the action of the loading piston.

Preferably, the fastener comprises a rectangular plate, and the rectangular plate is provided with two screws, and the inside of the rubber film is in a sealed state by tightening the screws;

The length of the rectangular plate matches the length of the rigid loading plate, and a hole of the same size as the connecting piece is provided in the center of the rectangular plate, and the connecting piece can pass through the hole so that the The fastener is sleeved on the connecting piece.

Preferably, the connector is provided with a guide hole, the guide hole is used for connecting a hose for drainage, one end of the hose is connected with the guide hole, and the other end is connected with the outside.

Preferably, the rigid loading plate is provided with a water seepage hole for draining the water in the geotechnical sample, so that the water in the geotechnical sample flows into the connecting piece through the water seepage hole , and then discharged to the outside through the guide hole.

Preferably, the loading device further comprises four stress sensors and four displacement sensors,

The four stress sensors are respectively fixed on the loading piston for sensing the magnitude of the load acting on the geotechnical sample by the loading device;

The displacement sensor is used for sensing the strain of the geotechnical sample under the action of the load.

Preferably, the loading device further includes a sample loading part, and the sample loading part includes a fixing plate and a sample loading rack;

The sample loading rack includes a first beam and a second beam, and the first beam and the second beam form a guide rail;

The bottom of the fixing plate is provided with a first groove and a second groove;

The fixing plate is provided with a U-shaped groove, and the U-shaped groove is used for clamping the sliding loading member;

The fixing plate is arranged on the sample loading rack, and the first groove and the second groove of the fixing plate are respectively clamped on the first beam and the second beam, so that the The fixing plate can slide in the direction of the guide rail.

Preferably, the loading piston is driven by a motor system.

Preferably, the geotechnical sample and the four rigid loading plates are encapsulated in the flexible rubber film to form a cube.

Compared with the prior art, the present invention has at least one of the following beneficial effects:

In the above structure of the present invention, four rigid sliding plates and flexible films are used to load the stress, thereby overcoming the defects of using only rigid loading plates and flexible films for loading.

In the above structure of the present invention, the rigid loading plate and the geotechnical sample are completely enclosed in the accommodating space by the rubber film, and sealed by fasteners, which changes the conventional structure (the conventional structure is that the rigid loading plate is arranged on the rubber outside the membrane), the full-scale stress path test is realized by changing the setting position of the rubber membrane. In contrast, in the prior art, the rubber film of the general composite true triaxial instrument can only wrap the soil sample, the rigid loading plate is outside the rubber film, and the stress exerted by the rigid plate on the soil sample in the horizontal direction is equal to the pressure. The sum of the chamber water pressure and the rigid loading plate pressure cannot be less than the water pressure in the confining chamber, so any Lode angle test from 0 to 360 degrees cannot be performed. The loading device designed in the present invention cleverly designs the rubber film outside the rigid loading plate, and applies the load through the loading piston connected to the rigid loading plate, so that the pore water pressure can be directly measured, and the soil sample can be directly measured in this area during shearing. The pressure in the direction is less than the water pressure in the confining pressure chamber, and any Lode angle test from 0 to 360 degrees can be carried out.

Further, in the present invention, by arranging a sliding block between the loading piston and the rigid loading plate, the piston can always be located in the central position of the deformed central accommodating space, and the load can be applied to the central position of the rock and soil sample to ensure that the uniform distribution of internal stress in the rock.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

1 is a vertical cross-sectional view of the structural principle of a rigid-flex composite true triaxial loading device according to an embodiment of the present invention;

2a is a front view of a second rigidly loaded plate in an embodiment of the present invention;

2b is a side view of a second rigidly loaded plate in an embodiment of the present invention;

2c is a top view of a second rigid loading plate in an embodiment of the present invention;

3a is a front view of a fixing plate in an embodiment of the present invention;

Fig. 3b is a side view of a fixing plate in an embodiment of the present invention;

3c is a bottom view of the fixing plate in an embodiment of the present invention;

Figure 4a is a front view of a sample loading rack in an embodiment of the present invention;

4b is a side view of the sample loading rack in an embodiment of the present invention;

4c is a top view of the sample loading rack in an embodiment of the present invention;

Fig. 5a is the front view of the sample loading part in one embodiment of the present invention;

Figure 5b is a side view of a sample loading part in an embodiment of the present invention;

Fig. 5c is a top view of the sample loading part in an embodiment of the present invention;

6a is a front view of the loading process of the sample loading part in an embodiment of the present invention;

Fig. 6b is a side view of the loading process of the sample loading part in an embodiment of the present invention;

Figure 6c is a bottom view of the loading process of the sample-loading component in an embodiment of the present invention;

7 is a perspective view of a sample loading component in an embodiment of the present invention;

FIG. 8 is a perspective view of the loading process of the sample-loading component in an embodiment of the present invention;

The symbols in the figure are respectively: geotechnical sample 10, test chamber 20, sliding loading member 30, first guide hole 41, second guide hole 42, first hose 43, second hose 44, first water seepage hole 45. Second water seepage hole 46, fixing plate 51, sample loading rack 52, first rigid loading plate 301, second rigid loading plate 302, third rigid loading plate 303, fourth rigid loading plate 304, first fastener 305, second fastener 306, third fastener 307, fourth fastener 308, first connector 309, second connector 310, third connector 311, fourth connector 312, first sliding block 313, second sliding block 314, third sliding block 315, fourth sliding block 316, first stress sensor 317, second stress sensor 318, third stress sensor 319, fourth stress sensor 320, first loading piston 321 , the second loading piston 322, the third loading piston 323, the fourth loading piston 324, the first screw 325, the second screw 326, the first groove 511, the second groove 512, the first U-shaped groove 513, the second The U-shaped groove 514 , the third U-shaped groove 515 , the first beam 521 , and the second beam 522 .

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Referring to FIG. 1, it is a schematic structural diagram of a rigid-flex composite true triaxial loading device with a rubber film outer loading plate according to an embodiment of the present invention, including a sliding loading member 30 and a rubber film; wherein, the sliding loading member 30 includes four rigid loading plate. The four rigid loading plates are respectively a first rigid loading plate 301, a second rigid loading plate 302, a third rigid loading plate 303 and a fourth rigid loading plate 304, and the four rigid loading plates overlap each other in a slidable manner relative to each other. A frame with a central accommodating space is formed, and the central accommodating space formed by the four rigid loading plates is used to accommodate the geotechnical sample 10, so that the geotechnical sample 10 is clamped between the four rigid loading plates. Specifically, the lower end of the third rigid loading plate 303 is located on the upper surface of the fourth rigid loading plate 304, and the other end is suspended, so that the third rigid loading plate 303 can move along the loading plate. The upper surface of 304 slides. The remaining rigidly loaded plates are lapped in sequence in the same manner. The four rigid loading plates include two vertical plates and two horizontal plates. The second rigid loading plate 302 and the fourth rigid loading plate 304 are vertical plates for applying vertical loads to the geotechnical sample 10. The first rigid loading plate The plate 301 and the third rigid loading plate 303 are horizontal plates, which are used to apply horizontal load to the geotechnical sample 10 .

Referring to FIG. 1 , the sliding loading member 30 further includes loading pistons acting on the four rigid loading plates respectively, and connecting the four loading pistons with the intermediate positions of the four rigid loading plates respectively, so that the loading pistons are directed toward the connected ones. A rigidly loaded plate applies the load. The four loading pistons are the first loading piston 321 , the second loading piston 322 , the third loading piston 323 and the fourth loading piston 324 respectively. As a preferred way, the four loading pistons can be driven by a motor system. The four rigid loading plates are respectively connected to a loading piston, that is, the first loading piston 321 is connected to the first rigid loading plate 301, the first loading piston 321 applies a load to the first rigid loading plate 301; the second loading piston 322 is connected to the second rigid loading plate 301. The rigid loading plate 302 is connected, and the second loading piston 322 applies a load to the second rigid loading plate 302; the third loading piston 323 is connected to the third rigid loading plate 303, and the third loading piston 323 applies a load to the third rigid loading plate 303; The fourth loading piston 324 is connected to the fourth rigid loading plate 304 , and the fourth loading piston 324 applies a load to the fourth rigid loading plate 304 .

Four rigid loading plates are overlapped with each other in four directions to form a frame with a central accommodating space, so that they can slide with each other in the horizontal and vertical directions under the action of the loading piston, so that the After the geotechnical sample 10 is strained under the action of the load, the central accommodating space also becomes smaller, so as to ensure that the load is always applied to the geotechnical sample 10 .

The sliding loading member 30 includes four fasteners, the four fasteners are a first fastener 305, a second fastener 306, a third fastener 307 and a fourth fastener 308, and the four fasteners are respectively The fasteners are respectively arranged on the outer side of each rigid loading plate and are fixedly connected with each rigid loading plate, and the four fasteners are located on the outer side of the rubber film. That is, the first fastener 305 is arranged on the outer side of the first rigid loading plate 301 , the second fastener 306 is arranged on the outer side of the second rigid loading plate 302 , and the third fastener 307 is arranged on the outer side of the third rigid loading plate 303 . On the outer side, the fourth fastener 308 is arranged on the outer side of the fourth rigid loading plate 304, and a combined loading system is formed between the four rigid loading plates and the four fasteners.

The rubber film is wrapped around the four rigid loading plates and the outside of the geotechnical sample 10, and the rubber film is located between the rigid loading plate and the fastener, and the rubber film is clamped by the fastener, so as to seal the geotechnical sample 10 role. Thus, the geotechnical sample 10 and the four rigid loading plates are encapsulated in a cube-shaped rubber film (not shown in the figure), thereby also forming a cube shape, so that the geotechnical sample 10 is clamped by the sliding loading member 30 hold. The flexible film applies a load to the geotechnical sample 10 in the direction perpendicular to both sides of the frame, so that in the other two directions where the rigid loading plate is not set, the load applied by the water pressure (flexible load), the water pressure acts directly on the other two directions. Above the rubber film in both directions. In the specific implementation process, the above-mentioned loading device is placed in the test chamber 20, and the experiment process is carried out in the test chamber 20. During the experiment process, the test chamber 20 will be filled with water for applying the other two The water pressure in each direction (that is, the flexible load).

In other preferred embodiments, each fastener includes a rectangular plate, and the rectangular plate is provided with two screws, as shown in FIG. 3a, which are the first screw 325 and the second screw 326 respectively. The screw 325 and the second screw 326 keep the inside of the rubber film in a sealed state. The length of the rectangular plate matches the length of the rigid loading plate, and a hole of the same size as the connector is opened in the center of the rectangular plate, and the connector can pass through the hole, so that the fastener can fit over the connector.

In other preferred embodiments, in order to ensure that the loading pistons 321 , 322 , 323 , 324 still act on the center of the geotechnical sample 10 after the four rigid loading plates slide, so as to ensure the stress of the geotechnical sample 10 Evenly, sliding connection is achieved between the above four loading pistons and the four rigid loading plates through sliding blocks. The sliding loading member 30 further includes four connecting pieces and four sliding blocks, and the connecting pieces and the sliding blocks are detachably connected. In order to facilitate the connection between the sliding block and the rigid loading plate, threads can be provided on the other ends of the first connecting piece 309, the second connecting piece 310, the third connecting piece 311 and the fourth connecting piece 312 to connect with the first sliding piece 313 , the second sliding block 314 , the third sliding block 315 , and the fourth sliding block 316 are connected by nuts. In the process of sample loading, the connecting piece and the sliding block are separated. After the loading is completed, the screw between the sliding block and the connecting piece is tightened, so that the connecting piece and the sliding block are fixed together to transmit the load. Due to the existence of the sliding block, the sliding loading plates can slide relative to each other in the horizontal direction and the vertical direction under the action of the loading piston.

Referring to FIG. 1 , one end of the first connecting member 309 , the second connecting member 310 , the third connecting member 311 and the fourth connecting member 312 are respectively connected with the first rigid loading plate 301 , the second rigid loading plate 302 and the third rigid loading plate 301 , the second rigid loading plate 302 and the third rigid loading plate. The outer sides of the loading plate 303 and the fourth rigid loading plate 304 are fixedly connected to transmit loads to the rigid loading plates.

The first sliding block 313 is disposed between the first rigid loading plate 301 and the first loading piston 321 , the first loading piston 321 and the first sliding block 313 are slidably connected through a sliding bearing, and the first sliding block 313 is connected by a first connecting piece 309 is fixedly connected with the first rigid loading plate 301; with reference to Figures 2a, 2b and 2c, the second sliding block 314 is arranged between the second rigid loading plate 302 and the second loading piston 322, and the second loading piston 322 is connected to the first The two sliding blocks 314 are slidably connected through sliding bearings, the second sliding block 314 is fixedly connected to the second rigid loading plate 302 through the second connecting member 310 ; the third sliding block 315 is arranged on the third rigid loading plate 303 and the third loading piston Between 323, the third loading piston 323 and the third sliding block 315 are slidably connected through a sliding bearing, and the third sliding block 315 is fixedly connected to the third rigid loading plate 303 through the third connecting piece 311; the fourth sliding block 316 is arranged on the Between the fourth rigid loading plate 304 and the fourth loading piston 324, the fourth loading piston 324 and the fourth sliding block 316 are slidably connected through a sliding bearing, and the fourth sliding block 316 is connected to the fourth rigid loading plate through the fourth connecting member 312 304 is fixed. In the specific implementation process, each connecting piece and the sliding block are separated during the sample loading process. After the sample loading, the screws between the sliding block and the connecting piece are tightened, so that the connecting piece and the sliding block are fixedly connected to each other. transfer the load together.

In the above embodiment, the sliding connection is realized between the four loading pistons and the four rigid loading plates through sliding blocks, which can ensure that the four loading pistons still act on the geotechnical sample 10 after the four rigid loading plates slide. In order to ensure that the stress of the geotechnical sample 10 is uniform, each sliding block is fixedly connected to each rigid loading plate, and is slidably connected to the loading piston along the strain direction of the geotechnical sample 10 . In this way, after the geotechnical sample 10 is strained and the rigid loading plate slides, the sliding block drives the connecting piece and the rigid loading plate to slide, so that the force from the loading piston is always located in the center of the deformed central accommodating space The position can ensure that the load is applied to the central position of the geotechnical sample 10, ensuring a uniform distribution inside the geotechnical sample.

In other embodiments, the loading device further includes a stress sensor and a displacement sensor. The stress sensor is used to sense the magnitude of the load acting on the geotechnical sample 10 by the loading device. The displacement sensor is used to sense the strain of the geotechnical sample 10 under the action of the load.

In order to measure the first loading piston 321, the second loading piston 322, the third loading piston 323 and the fourth loading piston 324 applied to each of the first rigid loading plate 301, the second rigid loading plate 302, the third rigid loading plate 303, the The load on the four rigid loading plates 304, the first stress sensor 317, the second stress sensor 318, the third stress sensor 319 and the fourth stress sensor 320 are provided inside the test chamber 20, the first stress sensor 317, the second stress sensor 318, the third stress sensor 319, and the fourth stress sensor 320 are all annular, and are respectively fixed on the first loading piston 321, the second loading piston 322, the third loading piston 323, and the fourth stress sensor 320. The loading piston is fixed to the horizontal load direction, and the other two load pistons are located in the vertical load direction.

In addition, in order to measure the strain of the geotechnical sample 10 under load, displacement sensors (not shown in the figure) are respectively provided on the second loading piston 322 and the fourth loading piston 324 for measuring displacement in the vertical direction. In the other two horizontal directions, the first loading piston 321 and the third loading piston 323 are used for applying pressure in the horizontal direction, and a displacement sensor (not shown in the figure) is also provided for measuring the displacement in the horizontal direction.

In other preferred embodiments, the slip-loading member 30 may be adjusted appropriately for a particular test scenario. For example, on the rigid loading plate acting on the closed geotechnical sample 10 in the upper and lower directions (the vertical load direction), that is, the second rigid loading plate 302 and the fourth rigid loading plate 304 are respectively provided with first water seepage holes 45, In the second water seepage hole 46 , the water in the geotechnical sample 10 is discharged into the second connecting piece 310 and the fourth connecting piece 312 through the first water seepage hole 45 and the second water seepage hole 46 . The second connecting member 310 and the fourth connecting member 312 are respectively provided with a conduit for connecting the water seepage hole and the guide hole. The hole 41 , the second guide hole 42 and the plastic first hose 43 and the second hose 44 connected with the first guide hole 41 and the second guide hole 42 are connected to the outside of the test chamber 20 . The plastic first hose 43 and the second hose 44 can be used to measure drainage in a drainage shear test, or to measure water pressure in an undrained test.

In other preferred embodiments, as shown in FIG. 5a, FIG. 5b, FIG. 5c and FIG. 7, the loading device further includes a sample loading part, the sample loading part includes a fixing plate 51 and a sample loading rack 52, and the fixing plate 51 is arranged on the sample loading rack 52 , the bottom of the fixing plate 51 is provided with two grooves, namely a first groove 511 and a second groove 512 , which are used for clamping the sample rack 52 .

4a, 4b and 4c, the sample loading frame 52 includes a first beam 521 and a second beam 522, and the two beams form a guide rail; the fixing plate 51 is placed on the sample loading frame 52, and the fixing plate 51 The first groove 511 and the second groove 512 are respectively clamped on the first beam 521 and the second beam 522, so that the fixing plate 51 can slide along the direction of the guide rail, and the bottom end of the sample loading rack 52 is straightened for three axes indoor.

3a, 3b and 3c, there are three U-shaped grooves on the fixing plate 51, which are a first U-shaped groove 513, a second U-shaped groove 514 and a third U-shaped groove 515, respectively. The groove is used for snapping the sliding loading member 30 . In the specific implementation, referring to FIGS. 6a, 6b, 6c and 8, during sample loading, the fourth rigid loading plate 304 at the lower part is placed on the fixing plate 51, and the fourth rigid loading plate at the lower part is placed on the fixing plate 51. The fourth connector 312 connected to 304 is clamped to the fixing plate 51 through the first U-shaped groove 513 on the fixing plate 51, and the first screw 325 and the second screw 326 are respectively clamped to the second U-shaped groove 514, inside the third U-shaped groove 515 . The first rigid loading plate 301 , the second rigid loading plate 302 , the third rigid loading plate 303 and the fourth rigid loading plate 304 in the four directions and the geotechnical sample 10 are overlapped and installed on the fixing plate 51 . . The geotechnical sample 10 and the loading plate are sent into the triaxial chamber by sliding the fixing plate 51, and then the sample loading is completed by tightening the screws on the connecting piece and the sliding block.

In this example, the sample loading process needs to be carried out with an external sample loading device as a support. The sample is loaded on the external sample loading device. After the sample is sealed, it is sent into the test chamber through the sample loading device, and then Connect with the sliding device in four directions. It can make the whole composed of rigid loading plate, connecting piece and fastener can enter the test chamber accurately, and can accurately connect with the sliding device.

The loading device of the above embodiment uses four rigid loading plates and flexible films to load stress, thereby overcoming the defects of only using rigid plates and flexible films for loading. At the same time, the loading device designed in the present invention cleverly designs the rubber film and the rigid loading plate, and applies the load through the loading piston connected to the rigid loading plate, so that the pore water pressure can be directly measured, and the soil sample can be directly measured during shearing. The pressure in this direction is less than the water pressure in the confining pressure chamber, and any Lode angle test from 0 to 360 degrees can be performed. In the shearing process, when the Lord angle takes different values from 0 to 360, Sig1(σ ₁ ) refers to the vertical rigid plate pressure, sig2(σ ₂ ) refers to the water pressure in the confining pressure chamber, Sig3(σ 1 ) ₃ ) refers to the horizontal rigid plate pressure, the changes of sig2(σ ₂ ) and sig3(σ ₃ ) are related to the changes of sig1(σ ₁ ), sig2(σ ₂ ) and sig3(σ ₃ ) are both It varies with the change of sig1(σ ₁ ), but the variation laws corresponding to different Lord angles are different. For example, if the stress in each direction at the initial stage of shearing is 100kPa, then the stress during shearing at different Lord angles is The change is: when taking 0 degree Lord angle: Sig1(σ ₁ ) if +50kPa, Sig2(σ ₂ ) then -25kPa, Sig3(σ ₃ ) then -25kPa; when taking 30 degree Lord angle: Sig1(σ ₁ ) if +50kPa, Sig2(σ ₂ ) is unchanged, Sig3(σ ₃ ) is -50kPa; when taking the Lord angle of 60 degrees: Sig1(σ ₁ ), if +50kPa, Sig2(σ ₂ ), then +50kPa, Sig3(σ ₃ ) is -100kPa; it can be obtained that under some Lord angles (such as 60 degrees), the water pressure in the confining pressure chamber (sig2(σ ₂ )=100+50=150kPa) is higher than the horizontal rigid plate pressure ( sig3(σ ₃ )=100-100=0kPa) is much larger. Like the general composite true triaxial instrument, the rubber membrane can only wrap the soil sample, and the rigid plate is outside the rubber membrane. In this way, the stress exerted by the rigid plate on the soil sample in the horizontal direction is equal to the sum of the water pressure in the pressure chamber and the pressure of the rigid plate. Therefore, it cannot be less than the water pressure in the confining chamber. However, in this embodiment, the loading device wraps the rigid loading plate in the rubber membrane, which can realize that the pressure on the soil sample in this direction during shearing is less than the water pressure value in the confining pressure chamber, so that any Lord can be carried out from 0 to 360 degrees. angle test.

In the above, the present invention has been described by way of example only, but the present invention is not limited thereto. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various variations or modifications within the scope of the claims, which do not affect the essential content of the present invention.

Claims (9)

1. The utility model provides a real triaxial loading device of just gentle complex of rubber film outsourcing loading plate which characterized in that: the method comprises the following steps: a slide loading member and a rubber film; wherein,

the sliding load member comprises four rigid load plates; the four rigid loading plates are respectively provided with a loading piston, the outer sides of the rigid loading plates are connected with the loading pistons, and the loading pistons apply loads to the rigid loading plates connected with the loading pistons; the four rigid loading plates are respectively overlapped in four directions to form a frame with a central accommodating space, and the central accommodating space of the frame is used for accommodating and clamping rock-soil samples; the four rigid loading plates can slide relative to each other in the horizontal direction and the vertical direction under the action of each loading piston, so that the central accommodating space is reduced after the rock-soil sample is subjected to strain under the action of a load, and the load is ensured to be applied to the rock-soil sample all the time; the sliding loading component comprises four fasteners, the four fasteners are respectively and correspondingly arranged on the outer side of each rigid loading plate, and a combined loading system is formed between the four rigid loading plates and the four fasteners;

the rubber film is wrapped outside the frame and the rock-soil sample and is positioned between the rigid loading plate and the fastening piece, the rubber film is clamped through the fastening piece, so that the rock-soil sample is sealed, and the flexible film applies loads to the rock-soil sample along the direction perpendicular to the two sides of the frame.

2. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 1, wherein: the sliding loading part also comprises four connecting pieces and four sliding blocks;

the four connecting pieces are fixedly connected to the outer sides of the four rigid loading plates respectively and used for transferring load to the rigid loading plates;

the four sliding blocks are respectively arranged between each rigid loading plate and the loading piston, one end of each sliding block is detachably connected with the connecting piece, and the other end of each sliding block is in sliding connection with the loading piston through a sliding bearing, so that the sliding loading plates can freely slide along the direction perpendicular to the connected loading pistons;

it is realized that the four rigid loading plates can slide relative to each other in the horizontal direction and the vertical direction through the four sliding blocks under the action of the loading pistons respectively.

3. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 2, wherein: the fastener comprises a rectangular plate, two screws are arranged on the rectangular plate, and the interior of the rubber film is in a sealed state by screwing the screws tightly;

the length of the rectangular plate is matched with that of the rigid loading plate, a hole with the same size as the connecting piece is formed in the center of the rectangular plate, and the connecting piece can penetrate through the hole to enable the fastening piece to be sleeved on the connecting piece.

4. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 2, wherein: the connecting piece is provided with a guide hole, the guide hole is used for connecting a hose for drainage, one end of the hose is connected with the guide hole, and the other end of the hose is connected with the outside.

5. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 4, wherein: and the rigid loading plate is provided with water seepage holes for discharging water in the rock-soil sample, so that the water in the rock-soil sample flows into the connecting piece through the water seepage holes and then is discharged to the outside through the guide holes.

6. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 1, wherein: the loading device further comprises four stress sensors and four displacement sensors,

the four stress sensors are respectively fixedly connected to the loading piston and used for sensing the load of the loading device acting on the rock-soil sample;

and the displacement sensor is used for sensing the strain of the rock-soil sample under the action of the load.

7. The rigid-flexible composite true triaxial loading device of a rubber film outer wrapping loading plate according to claim 1, wherein: the loading device also comprises a sample loading component, and the sample loading component comprises a fixing plate and a sample loading frame;

the sample loading frame comprises a first cross beam and a second cross beam, and a guide rail is formed by the first cross beam and the second cross beam;

the bottom of the fixing plate is provided with a first groove and a second groove;

the fixed plate is provided with a U-shaped groove which is used for clamping the sliding loading part;

the fixing plate is arranged on the sample loading frame, and the first groove and the second groove of the fixing plate are respectively clamped on the first cross beam and the second cross beam, so that the fixing plate can slide along the direction of the guide rail.

8. The rigid-flexible composite true triaxial loading device of a rubber film overwrap loading plate according to any one of claims 1 to 7, wherein: the loading piston is driven by a motor system.

9. The rigid-flexible composite true triaxial loading device of a rubber film overwrap loading plate according to any one of claims 1 to 7, wherein: the rock-soil sample and the four rigid loading plates are packaged in the flexible rubber film to form a cube.

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