CN115046848A - Unloading simulation test device and simulation test method for surrounding rock excavation of soil-rock mixture tunnel - Google Patents

Abstract

The invention discloses an unloading simulation test device and a simulation test method for surrounding rock excavation of a soil-rock mixture tunnel. The combined sample loading auxiliary system comprises a cavity assembly and a discharging assembly, wherein the discharging assembly can uniformly mix stones and soil with different particle sizes in the cavity assembly when the stones and the soil fall into a sample loading cavity, and the microcomputer-controlled electro-hydraulic servo loading system can apply external confining pressure, internal confining pressure, axial pressure and torsional shear force to a sample. The invention can prepare the saturated soil-rock mixture hollow cylinder sample with uniform distribution of the rock blocks and no excessive macropores; the excavation unloading effect of the surrounding rock of the soil-rock mixture tunnel is simulated and reproduced more truly; recording the change of each relevant mechanical parameter of the sample in real time, and reflecting the damage evolution process of the soil-rock mixture surrounding rock during tunnel excavation.

Description

A simulation test device and simulation test device for excavation and unloading of surrounding rock of earth-rock mixture tunnel experiment method

technical field

The invention relates to the field of geotechnical engineering tests, in particular to a simulation test device and a simulation test method for excavation and unloading of surrounding rock of an earth-rock mixture tunnel.

Background technique

With the continuous development of urban scale, my country's rail transit construction is in full swing. Due to the "high excavation and low fill" leveling method adopted in the construction process of Chongqing and other southwestern mountainous cities, there are a large number of deep soil-rock mixed backfill areas with loose structure, high porosity, low strength and poor engineering performance. Tunnel excavation will inevitably pass through these deep soil-rock mixture backfill areas. Different from tunnel excavation in ordinary consolidated soil, in the process of tunnel construction in backfill soil, due to the low soil strength, poor hole-forming conditions, complex stress on surrounding rock, poor self-stabilizing ability and short self-stabilizing time after excavation disturbance , Disasters such as landslides, large deformations, and excessive surface subsidence are prone to occur during the construction process. However, due to insufficient understanding of the engineering properties of the surrounding rock of the soil-rock mixture, the unloading effect and damage evolution mechanism of the tunnel excavation process are not clear. Excessive safety margin, resulting in waste, there are also certain security risks. In addition, the lack of control over the unloading and deformation of the surrounding rock of the soil-rock mixture will also affect the construction period and increase the cost.

Therefore, there are several problems to be further studied for the unloading effect and damage evolution mechanism of the surrounding rock during the tunnel excavation in the under-consolidated deep soil-rock mixed backfill area. However, most of the current research on the mechanical properties of soil-rock mixtures is carried out in the form of direct shear or triaxial compression tests, which cannot simulate the unloading effect and principal stress diversion produced by the internal excavation of the surrounding rock. The deformed equipment is mainly suitable for pure soil or pure stone, and it is difficult to apply to highly discrete and heterogeneous media such as soil-rock mixture. It is difficult to prepare samples, and the soil-rock mixture itself is greatly affected by the size effect. Further magnifying the extreme physical property differences between soils and rocks leads to large errors in the research results.

In view of this, it is necessary to invent a soil-rock mixture tunnel surrounding rock excavation and unloading simulation test device, equipped with a relatively mature sample preparation scheme, to prepare a saturated soil-rock mixture hollow cylindrical test device with uniform distribution of blocks and no excessively large pores. Simulate and reproduce the excavation unloading effect of the surrounding rock of the soil-rock mixture more realistically; record the changes of the relevant mechanical parameters of the sample in real time, and reflect the damage evolution process of the surrounding rock of the soil-rock mixture during the tunnel excavation.

SUMMARY OF THE INVENTION

In view of the above deficiencies of the prior art, the present invention proposes a simulation test device and a simulation test method for excavation and unloading of the surrounding rock of a soil-rock mixture tunnel, so as to solve the problem that the prior art mentioned in the above background technology is difficult to prepare the distribution of boulders It is a technical problem that it is difficult to simulate and reproduce the unloading effect of the excavation and unloading effect of the surrounding rock of the soil-rock mixture tunnel more realistically.

To achieve the above object, the present invention provides the following technical solutions:

A simulation test device for excavation and unloading of surrounding rock of a soil-rock mixture tunnel, comprising a base assembly, a combined sample loading auxiliary system, a rubber membrane, a strain gauge, a computer-controlled electro-hydraulic servo loading system, a top pressure assembly and a water pressure gauge;

The combined sample loading auxiliary system includes a cavity assembly and a discharging assembly; the cavity assembly includes an inner sample loading sleeve, an outer sample loading sleeve and a permeable stone; the inner sample loading sleeve and the outer sample loading sleeve are coaxial is arranged on the base assembly, and a sample loading cavity is formed between the two, an inner pressure cavity is formed in the inner sample loading sleeve, and an outer pressure cavity is formed by the outer wall of the outer sample loading sleeve and the base assembly; The permeable stone is arranged on the base assembly, and is located between the inner sample-loading sleeve and the outer sample-loading sleeve;

There are two rubber films, one is detachably sleeved on the outer wall of the inner sample-loading sleeve, and the other is detachably sleeved on the inner wall of the outer sample-loading sleeve, and the strain gauge is provided on its outer surface;

The discharging assembly is detachably arranged in the sample loading cavity, and the discharging assembly can make the blocks of different particle sizes and soil mix uniformly when falling into the sample loading cavity;

After the sample loading in the sample loading chamber is completed, the discharging assembly is disassembled and the top pressure assembly is installed, so that the inner pressure chamber and the outer pressure chamber respectively form a closed space;

The water pressure gauge is provided with a plurality of and can measure the pressure of the outer space of the two rubber membranes respectively, and the top pressure component is also provided with a closable exhaust hole;

The microcomputer-controlled electro-hydraulic servo loading system is connected with the sample loading chamber and the two enclosed spaces outside the sample loading chamber, and the microcomputer-controlled electro-hydraulic servo loading system can simultaneously apply external confining pressure to the sample loading chamber, Internal confining pressure, axial pressure and torsional shear.

It can be seen from the above that in this application, when the rock and soil of different particle sizes fall into the sample-loading cavity, they can be evenly mixed in the sample-loading cavity. Excessive pore; after the sample loading, disassemble the combined sample loading auxiliary system, install the top pressure component and water pressure gauge after the sample in the rubber film is stable, and apply external pressure to the sample loading cavity through the microcomputer-controlled electro-hydraulic servo loading system Confining pressure, internal confining pressure, axial pressure and torsional shear force, so as to simulate and reproduce the excavation and unloading effect of the surrounding rock of the soil-rock mixture tunnel more realistically.

Further, the base assembly includes an instrument base, a bottom sealing disc, a rigid outer wall and a sample base; the bottom sealing disc is arranged on the instrument base, and the rigid outer wall is erected at the bottom of the bottom sealing disc On the sealing plate, the outer pressure cavity is formed between the rigid outer wall and the outer wall of the outer sample sleeve, and the top pressure component is detachably provided on the top of the rigid outer wall; the sample base is arranged at the On the bottom sealing disc, the inner sample-loading sleeve and the outer sample-loading sleeve are respectively coaxially arranged on the sample base, and a plurality of liquid passages are arranged on the bottom sealing disc. One end of the pipeline is connected to the microcomputer-controlled electro-hydraulic servo loading system, and the other end is connected to the external pressure chamber or to the internal pressure chamber through the sample base. The microcomputer-controlled electro-hydraulic servo loading system can control the The water intake of the inner pressure chamber and the outer pressure chamber.

Further, the microcomputer-controlled electro-hydraulic servo loading system includes an external pressure servo control machine, an internal pressure servo control machine, a back pressure servo control machine and a torsion shear control machine; The external pressure chamber is connected and can control the water intake of the external pressure chamber; the internal pressure servo control machine is connected with the internal pressure chamber through the liquid passage pipe, and can control the intake of the internal pressure chamber. The amount of water; the back pressure servo controller is connected to the permeable stone through the sample base, and can give vertical pressure to the sample loading cavity; the torsion shear controller is connected to the sample base, And can drive the sample base to rotate.

Further, the discharging assembly includes a sample loading funnel and a material barrel; the material barrel is detachably arranged in the sample loading cavity, and a plurality of the funnels are arranged on the material barrel respectively, The funnel is communicated with the material cylinder.

Further, the top pressing assembly includes a top sealing disc, a top pressing plate and a reaction force frame; the top sealing disc is detachably arranged on the top of the rigid outer wall, and can abut against the top of the sample loading cavity, and the top The pressing plate is arranged on the top sealing plate, and is connected with the instrument base through the reaction force frame.

Further, the sample loading funnel is also provided with a funnel partition.

Further, a tight hoop sleeve is also provided outside the rigid outer wall.

Further, the bottom sealing disc and the sample base are respectively provided with liquid collecting grooves, and the liquid collecting grooves are communicated with the liquid passage pipes.

Further, a scale is also provided on the sample loading sleeve.

The beneficial effects of the present invention are:

(1) In the present invention, the combined sample loading auxiliary system is used, and by controlling the sample loading time, the different particle sizes of the rock and the soil are uniformly mixed when falling, without excessive pores, which overcomes the problem of the internal rock in the sample in the mechanical test of the soil-rock mixture. The distribution is locally concentrated and the pores are too large.

(2) The present invention can control the stress state of the soil-rock mixture hollow cylinder sample through the external pressure servo control system, the internal pressure servo control system and the back pressure servo control system, and more realistically simulate and reproduce the surrounding rock of the soil-rock mixture tunnel. The excavation unloading effect reflects the damage evolution process of the surrounding rock of the soil-rock mixture during tunnel excavation.

(3) The present invention can apply torque through the torsional shear control system to simulate the principal stress turning generated during the excavation process.

(4) In the present invention, the thickness of each loading can be controlled by the scale on the loading sleeve during loading, so as to control the relative compactness of the sample.

(5) The present invention can consciously adjust the particle size of the boulders in the last layer of the loaded sample to ensure that no large boulders are exposed on the surface and to ensure the flatness of the sample surface.

(6) The principle of the instrument of the present invention is simple and easy to understand, the operation is simple, and it can be used for conventional triaxial tests after a little adjustment, and has high cost performance.

Description of drawings

In order to describe the specific embodiments of the present invention more clearly, the accompanying drawings required for the specific embodiments will be briefly introduced below. In all the drawings, elements or sections are not necessarily drawn to actual scale.

The present invention is further described below in conjunction with accompanying drawing and embodiment, wherein:

Figure 1 is a schematic diagram of the overall structure of the combined sample loading auxiliary system;

2 is a schematic diagram of a microcomputer-controlled electro-hydraulic servo loading system and a top pressure assembly;

Figure 3 is a schematic diagram and a top view of the combined sample loading auxiliary system;

4 is a schematic diagram and a top view of a bottom sealing disc;

Figure 5 is a schematic diagram of an external sample sleeve;

Fig. 6 is the schematic diagram of the inner sample sleeve;

Reference number:

1- base assembly; 11- instrument base; 12- bottom sealing plate; 13- rigid outer wall; 14- sample base; 15- liquid pipeline; 16- liquid collection tank; 17- tight cuff;

2-Combined sample loading auxiliary system; 21-Cavity assembly; 211-Inner sample loading sleeve; 212-External sample loading sleeve; 213-Water permeable stone; 214-Sampling cavity; 215-Internal pressure cavity; ; 22-Discharging component; 221-Sampling funnel; 222-Material barrel; 223-Funnel partition;

3- Rubber film;

4- strain gauge;

5-Microcomputer controlled electro-hydraulic servo loading system; 51-External pressure servo control machine; 52-Internal pressure servo control machine; 53-Back pressure servo control machine; 54-Torsion shear control machine;

6-Top pressure assembly; 61-Top sealing plate; 611-Vent hole; 62-Top pressure plate; 63-Reaction frame;

7- Water pressure gauge.

Detailed ways

Embodiments of the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

It should be noted that the accompanying drawings are only used for exemplary description, and are only schematic diagrams rather than actual drawings, and should not be construed as limiting the present invention.

This embodiment provides a simulation test device for excavation and unloading of surrounding rock of a soil-rock mixture tunnel, as shown in FIGS. 1 to 6 , including a base assembly 1 , a combined sample loading auxiliary system 2 , a rubber membrane 3 , and a strain gauge 4 , Microcomputer control electro-hydraulic servo loading system 5, top pressure component 6 and water pressure gauge 7.

This embodiment is mainly divided into two stages, one is the sample loading stage, and the other is the experimental stage. After the sample loading is completed, part of the structure is disassembled and other structures are installed to realize the experimental stage.

The base assembly 1 serves as the basis of the entire device. In other solutions, it may specifically include an instrument base 11, a bottom sealing disc 12, a rigid outer wall 13 and a sample base 14; the bottom sealing disc 12 is provided on the instrument base 11, and the rigid outer wall 13 is erected on the bottom sealing plate 12, an external pressure cavity 216 is formed between the rigid outer wall 13 and the outer wall of the outer sample sleeve 212, the top of the rigid outer wall 13 is detachably provided with a top pressure component 6; the sample base 14 is located at the bottom On the sealing disc 12, the inner sample-loading sleeve 211 and the outer sample-loading sleeve 212 are respectively coaxially arranged on the sample base 14, and a plurality of liquid passages 15 are arranged on the bottom sealing disc 12, and one end of the liquid passages 15 is controlled by the microcomputer. The electro-hydraulic servo loading system 5, the other end is connected with the external pressure chamber 216 or through the sample base 14 and the internal pressure chamber 215. The microcomputer-controlled electro-hydraulic servo loading system 5 can control the water intake of the internal pressure chamber 215 and the external pressure chamber 216 .

The first is the sample loading stage, please refer to Figure 1, Figure 3-Figure 6; the combined sample loading auxiliary system 2 includes a cavity assembly 21 and a discharging assembly 22; the cavity assembly 21 includes an inner sample loading sleeve 211 and an outer sample loading sleeve 212 and the permeable stone 213; the inner sample-loading sleeve 211 and the outer sample-loading sleeve 212 are coaxially arranged on the base assembly 1, and a sample-loading cavity 214 is formed between them, and an internal pressure chamber 215 is formed in the inner sample-loading sleeve 211 , the outer wall of the outer sample sleeve 212 and the base assembly 1 form an external pressure cavity 216 ; It should be understood that the sample loading cavity 214 is an elongated annular body, and is used for filling soil and boulders therein.

There are two rubber films 3, one rubber film 3 is detachably sleeved on the outer wall of the inner sample-loading sleeve 211, and the other rubber film 3 is detachably sleeved with the inner wall of the outer sample-loading sleeve 212, and is on its outer surface. A strain gauge 4 is provided. It should be understood that the outer surface of the rubber film 3 is the side away from the other rubber film 3, and after the sample loading is completed, the inner sample loading sleeve 211 and the outer sample loading sleeve 212 should be removed, and the sample should be left to stand. Its state is stable.

Specifically, the inner sample sleeve 211 and the outer sample sleeve 212 are assembled into a whole by four 90° flaps, and the top of the inner sample sleeve 211 and the outer sample sleeve 212 form an inverted trapezoidal cross-section groove. The cylinder 222 is connected to ensure that the rock and soil fall into the sample-loading cavity 214 between the inner sample-loading sleeve 211 and the outer sample-loading sleeve 212 during sample loading, and a hollow cylindrical sample is prepared. The rubber film 3 is covered on the outer side of the inner sample loading sleeve 211 , the rubber film 3 is covered on the inner side of the outer sample loading sleeve 212 , and the strain gauges 4 are arranged at the corresponding positions. It should be understood that the rubber film 3 is provided on the permeable stone 213 .

The rock and soil are put into the sample loading cavity 214 through the discharging assembly 22. The discharging assembly 22 is detachably arranged in the sample loading cavity 214. The discharging assembly 22 can make the blocks and soils of different particle sizes fall into the loading cavity. Mix evenly within 214 hours.

In other solutions, the discharging assembly 22 includes a sample loading funnel 221 and a material barrel 222; the material barrel 222 is detachably arranged in the sample loading cavity 214, and a plurality of funnels are arranged on the material barrel 222, respectively. The material cylinder 222 is communicated. It should be understood that, when loading samples, the loading funnels 221 with different heights are filled with rock and soil of different particle sizes, and the rock and soil reach the loading cavity 214 along the annular material cylinder 222. The funnel is filled with soil, the lower funnel is filled with boulders, and the size of the boulders gradually increases from top to bottom. When discharging, put the soil sample at the highest position first, and then fill in the different particle sizes according to the calculated particle gradation layer, so that the rock and soil are mixed evenly when falling. After each sample of a certain thickness is filled, it needs to be compacted and leveled, and the next filling will be carried out after the deformation is stable, and finally a uniform and dense sample will be obtained. In this embodiment, three sample loading funnels 221 are detachably provided.

After completing the sample loading, remove the inner sample loading sleeve 211 and the outer sample loading sleeve 212, let the sample stand for stability, and then install the top pressure assembly 6 so that the inner pressure chamber 215 and the outer pressure chamber 216 respectively form a closed space.

Please refer to FIG. 2 to FIG. 6 together. The water pressure gauge 7 is provided with a plurality of and can measure the pressure of the outer space of the two rubber membranes 3 respectively. The top pressure component 6 is also provided with a closable exhaust hole 611 . It should be understood that, by opening and closing the exhaust hole 611, the pressure of the outer space of the two rubber membranes 3 after water injection can be adjusted, that is, the internal pressure and external pressure of the sample, and the internal pressure of the sample can be read through the water pressure gauge 7. pressure and external pressure.

The microcomputer-controlled electro-hydraulic servo loading system 5 is connected to the sample loading chamber 214 and the two enclosed spaces outside the sample loading chamber 214 . The microcomputer-controlled electro-hydraulic servo loading system 5 can simultaneously apply external confining pressure, internal confining pressure, shaft compressive and torsional shear.

In other solutions, the microcomputer-controlled electro-hydraulic servo loading system 5 includes an external pressure servo control machine 51, an internal pressure servo control machine 52, a back pressure servo control machine 53 and a torsion shear control machine 54; The pipeline 15 is connected with the external pressure chamber 216, and can control the water intake of the external pressure chamber 216; the internal pressure servo controller 52 is connected with the internal pressure chamber 215 through the liquid passage 15, and can control the water intake of the internal pressure chamber 215; The pressure servo controller 53 is connected to the permeable stone 213 through the sample base 14, and can give and control the vertical pressure of the sample loading chamber 214 by controlling the liquid entering the sample through the permeable stone 213; the torsional shear controller 54 and The sample base 14 is connected and can drive the sample base 14 to rotate. It should be understood that the torsional shear control machine 54 can give the sample torsional shear force, and the axial pressure given by the back pressure servo control machine 53 can be read by the strain gauge 4 .

In other solutions, the top pressing assembly 6 includes a top sealing disc 61, a top pressing plate 62 and a reaction force frame 63; the top sealing disc 61 is detachably arranged on the top of the rigid outer wall 13, and can abut against the top of the sample loading chamber 214, and the top pressing plate 62 is arranged on the top sealing plate 61, and is connected with the instrument base through the reaction force frame 63. The vertical load can be transmitted to the reaction force frame 63 through the top pressure plate 62 . In this embodiment, the reaction force frame 63 includes a connecting rod arranged on the base of the instrument, a connecting plate slidably arranged on the connecting rod, and a limit block for limiting the height position of the connecting plate, and the bottom surface of the connecting plate is connected with the top pressure plate 62 .

In other solutions, the sample loading funnel 221 is further provided with a funnel partition 223 . The funnel partition 223 can ensure that the filled rock and soil are evenly distributed on the horizontal plane.

In other solutions, the rigid outer wall 13 is further provided with a tight cuff 17 , and by providing the tight cuff 17 , the deformation effect of the liquid in the external pressure chamber 216 on the rigid outer wall can be reduced.

In other solutions, the bottom sealing disc 12 and the sample base 14 are respectively provided with liquid collecting grooves 16 , and the liquid collecting grooves 16 are communicated with the liquid passage 15 .

In other solutions, scales are also provided on the sample-loading sleeve. The thickness of each sample can be controlled by the scale to control the relative compactness of the sample.

The specific steps of the simulation test method of the embodiment are as follows:

(1) Assemble the combined sample loading auxiliary system 2, first disassemble the reaction force frame 63, install the inner sample loading sleeve 211 and the outer sample loading sleeve 212 above the sample base 14, and place the annular permeable stone 213 between the two sleeves. ;

(2) Put the rubber film 3 on the outer side of the inner sample loading sleeve 211, cover the rubber film 3 on the inner side of the outer sample loading sleeve 212, and set the strain gauge 4 at the corresponding position;

(3) Install the material barrel 222 and the sample loading funnel 221 above the sample loading sleeve, the outer wall of the material barrel 222 is connected with the sample loading funnel 221, the outer wall of the material barrel 222 is connected with the outer sample loading sleeve 212, and the inner liner of the material barrel 222 is connected through the connecting piece Connect with the inner sample sleeve 211;

(4) Filling the sample, filling the different size of rock in the loading funnel 221 of different heights, the rock arrives at the sample loading cavity 214 along the annular sample loading channel, and by controlling the sample loading time, the different particle size blocks The stone and soil are evenly mixed when falling, and each sample of a certain thickness needs to be compacted and leveled, and the next filling will be performed after the deformation is stable;

(5) After the sample loading is completed, remove the combined sample loading auxiliary system 2, remove the inner sample loading sleeve 211 and the outer sample loading sleeve 212, and leave the sample to stand until its state is stable;

(6) Install the reaction force frame 63 and the top sealing disc 61, and calibrate the readings of the inner cavity water pressure gauge 7 and the outer cavity water pressure gauge 7;

(7) Open the exhaust hole 611, start injecting liquid into the inner pressure chamber 215 and the outer pressure chamber 216 through the liquid passage 15, and apply vertical pressure, and monitor the internal pressure, external pressure, and axial pressure readings in real time during this process. , stop the pressurization after the sample reaches the initial state, close the exhaust air, and wait for the reading to stabilize;

(8) According to the pre-designed stress path, use the microcomputer-controlled electro-hydraulic servo loading system 5 to adjust the stress state of the sample to carry out the test, observe the state of the sample and record the reading;

(9) After the test is completed, the liquid in the inner pressure chamber 215 and the outer pressure chamber 216 is removed as much as possible through the liquid passage 15, the vertical pressure and torque are removed, the reaction force frame 63 and the top sealing disc 61 are removed, the sample is removed and the Clean the instrument.

In the above-mentioned simulation test device and simulation test method for excavation and unloading of surrounding rock of a soil-rock mixture tunnel, the combined sample loading auxiliary system is used to control the timing of loading the sample, so that the blocks of different particle sizes and the soil are evenly mixed when falling, There is no excessively large pores, which overcomes the defects of local concentration of the distribution of the stones inside the sample and the excessively large pores in the mechanical test of the soil-rock mixture. At the same time, the stress state of the soil-rock mixture hollow cylinder sample can be controlled by the external pressure servo control system, the internal pressure servo control system and the back pressure servo control system, and the excavation and unloading of the surrounding rock of the soil-rock mixture tunnel can be simulated and reproduced more realistically. It reflects the damage evolution process of the surrounding rock of the soil-rock mixture during tunnel excavation.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that the foregoing embodiments can still be used for The recorded technical solutions are modified, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention, and should be included in the The invention is within the scope of the claims and description.

Claims (10)

1. a simulation test device for excavation and unloading of surrounding rock of earth-rock mixture tunnel, is characterized in that, comprises base assembly, combined sample loading auxiliary system, rubber membrane, strain gauge, microcomputer-controlled electro-hydraulic servo loading system, top pressure components and water pressure gauges; The combined sample loading auxiliary system includes a cavity assembly and a discharging assembly; the cavity assembly includes an inner sample loading sleeve, an outer sample loading sleeve and a permeable stone; the inner sample loading sleeve and the outer sample loading sleeve are coaxial is arranged on the base assembly, and a sample loading cavity is formed between the two, an inner pressure cavity is formed in the inner sample loading sleeve, and an outer pressure cavity is formed by the outer wall of the outer sample loading sleeve and the base assembly; The permeable stone is arranged on the base assembly, and is located between the inner sample-loading sleeve and the outer sample-loading sleeve; There are two rubber films, one is detachably sleeved on the outer wall of the inner sample-loading sleeve, and the other is detachably sleeved on the inner wall of the outer sample-loading sleeve, and the strain gauge is provided on its outer surface; The discharging assembly is detachably arranged in the sample loading cavity, and the discharging assembly can make the blocks of different particle sizes and soil mix uniformly when falling into the sample loading cavity; After the sample loading in the sample loading chamber is completed, the discharging assembly is disassembled and the top pressure assembly is installed, so that the inner pressure chamber and the outer pressure chamber respectively form a closed space; The water pressure gauge is provided with a plurality of and can measure the pressure of the outer space of the two rubber membranes respectively, and the top pressure component is also provided with a closable exhaust hole; The microcomputer-controlled electro-hydraulic servo loading system is connected with the sample loading chamber and the two enclosed spaces outside the sample loading chamber, and the microcomputer-controlled electro-hydraulic servo loading system can simultaneously apply external confining pressure to the sample loading chamber, Internal confining pressure, axial pressure and torsional shear. 2. A kind of simulation test device for excavation and unloading of surrounding rock of a soil-rock mixture tunnel according to claim 1, wherein the base assembly comprises an instrument base, a bottom sealing disc, a rigid outer wall and a sample base ; The bottom sealing disc is arranged on the instrument base, the rigid outer wall is erected on the bottom sealing disc, and the outer pressure cavity is formed between the rigid outer wall and the outer wall of the outer sample sleeve, The top end of the rigid outer wall is detachably provided with the pressing component; the sample base is provided on the bottom sealing disc, and the inner sample-loading sleeve and the outer sample-loading sleeve are respectively coaxially arranged on the bottom. The sample base and the bottom sealing plate are provided with a plurality of liquid-passing pipes, one end of the liquid-passing pipes is connected to the microcomputer-controlled electro-hydraulic servo loading system, and the other end is connected to the external pressure chamber or passes through the The sample base is communicated with the inner pressure chamber, and the microcomputer-controlled electro-hydraulic servo loading system can control the water inflow volume of the inner pressure chamber and the outer pressure chamber. 3. A simulation test device for excavation and unloading of surrounding rock of soil-rock mixture tunnel according to claim 2, characterized in that, the microcomputer-controlled electro-hydraulic servo loading system comprises an external pressure servo controller, an internal pressure servo control machine, back pressure servo control machine and torsion shear control machine; the external pressure servo control machine is connected with the external pressure chamber through the liquid passage pipe, and can control the water intake of the external pressure chamber; the internal pressure The pressure servo control machine is connected to the inner pressure chamber through the liquid passage, and can control the water inflow of the inner pressure cavity; the back pressure servo control machine is connected to the permeable stone through the sample base , and can give vertical pressure to the sample loading cavity; the torsion shear controller is connected with the sample base, and can drive the sample base to rotate. 4. A kind of simulation test device for excavation and unloading of surrounding rock of earth-rock mixture tunnel according to claim 3, characterized in that, the discharging assembly comprises a sample loading funnel and a material barrel; the material barrel is detachable The funnel is arranged in the sample loading cavity, and the funnel is provided with a plurality of them, which are respectively arranged on the material barrel, and the funnel is communicated with the material barrel. 5. A simulation test device for excavation and unloading of surrounding rock of a soil-rock mixture tunnel according to claim 4, wherein the top pressure assembly comprises a top sealing disc, a top pressure plate and a reaction force frame; the The top sealing plate is detachably arranged on the top of the rigid outer wall and can abut against the top of the sample loading chamber. The top pressing plate is arranged on the top sealing plate and passes through the reaction force frame and the instrument base. connected. 6 . A simulation test device for excavation and unloading of surrounding rock of an earth-rock mixture tunnel according to claim 5 , wherein a funnel baffle is also provided in the sample loading funnel. 7 . 7. A simulation test device for excavation and unloading of surrounding rock of an earth-rock mixture tunnel according to claim 6, characterized in that, the rigid outer wall is further provided with a hoop sleeve. 8. A simulation test device for excavation and unloading of surrounding rock of soil-rock mixture tunnel according to claim 7, characterized in that, a liquid collecting tank is respectively provided on the bottom sealing disc and the sample base , the liquid collecting tank is communicated with the liquid communication pipeline. 9 . A simulation test device for excavation and unloading of surrounding rock of an earth-rock mixture tunnel according to claim 8 , wherein a scale is also provided on the sample loading sleeve. 10 . 10. A simulation test method for excavation and unloading of surrounding rock of an earth-rock mixture tunnel, using the simulation test device for excavation and unloading of surrounding rock of an earth-rock mixture tunnel as described in any one of claims 1-9, wherein It is characterized in that, the simulation test method comprises the following steps: (1) To assemble the combined sample loading auxiliary system, first disassemble the top pressure assembly, install the inner sample loading sleeve and the outer sample loading sleeve above the sample base assembly, and place a ring-shaped permeable stone between the two sleeves; (2) Cover the outer side of the inner sample sleeve with a rubber film, cover the inner side of the outer sample sleeve with a rubber film, and set strain gauges at the corresponding positions; (3) Install the discharging assembly above the inner sample loading sleeve to make the two communicate; (4) Fill the sample, and fill the different heights of the unloading assembly with stones of different sizes, and the blocks arrive at the sample loading cavity along the unloading assembly 22. Mix evenly when falling, and compact and level the sample after each filling of a certain thickness, and then carry out the next filling after the deformation is stable; (5) After the sample loading is completed, remove the combined sample loading auxiliary system, remove the inner sample loading sleeve and the outer sample loading sleeve 212, and leave the sample to stand until its state is stable; (6) Install the top pressure component, and calibrate the readings of the inner cavity water pressure gauge and the outer cavity water pressure gauge; (7) Open the exhaust hole, and inject liquid into the inner pressure cavity and the outer pressure cavity through the microcomputer-controlled electro-hydraulic servo loading system, and apply vertical pressure, and monitor the internal pressure, external pressure, and axial pressure readings in real time during this process. , stop the pressurization after the sample reaches the initial state, close the exhaust air, and wait for the reading to stabilize; (8) According to the pre-designed stress path, the microcomputer-controlled electro-hydraulic servo loading system is used to adjust the stress state of the sample to carry out the test, observe the state of the sample and record the reading; (9) After the test is completed, remove all the liquid in the inner pressure chamber and the outer pressure chamber, remove the vertical pressure and torque, remove the top pressure component, remove the sample and clean the instrument.

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