CN115046848A - Unloading simulation test device and simulation test method for surrounding rock excavation of soil-rock mixture tunnel - Google Patents
Unloading simulation test device and simulation test method for surrounding rock excavation of soil-rock mixture tunnel Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 109
- 239000000203 mixture Substances 0.000 title claims abstract description 47
- 238000009412 basement excavation Methods 0.000 title claims abstract description 37
- 238000012360 testing method Methods 0.000 title claims abstract description 26
- 238000004088 simulation Methods 0.000 title claims abstract description 23
- 238000010998 test method Methods 0.000 title abstract description 6
- 239000002689 soil Substances 0.000 claims abstract description 26
- 239000004575 stone Substances 0.000 claims abstract description 25
- 238000007599 discharging Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 15
- 239000002245 particle Substances 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims description 35
- 238000007789 sealing Methods 0.000 claims description 33
- 229920001971 elastomer Polymers 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 23
- 239000012528 membrane Substances 0.000 claims description 18
- 238000005192 partition Methods 0.000 claims description 5
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 10
- 229920006395 saturated elastomer Polymers 0.000 abstract description 3
- 238000009827 uniform distribution Methods 0.000 abstract 1
- 238000010276 construction Methods 0.000 description 7
- 239000011148 porous material Substances 0.000 description 7
- 230000007547 defect Effects 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 238000011160 research Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
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- 238000012669 compression test Methods 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 230000005476 size effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/22—Investigating strength properties of solid materials by application of mechanical stress by applying steady torsional forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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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
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 unloading of surrounding rocks of a soil-rock mixture tunnel.
Background
With the continuous development of urban scale, the construction of rail transit in China is vigorous. Due to the fact that a leveling mode of 'high excavation and low filling' is adopted in the construction process of southwest mountain land cities of Chongqing and the like, a large number of deep and thick soil-rock mixed backfilling areas with loose structures, large porosity, low strength and poor engineering performance exist, tunnel excavation is carried out during rail transit construction, and the deep and thick soil-rock mixed body backfilling areas can inevitably pass through. Different from the tunnel excavation in common consolidated soil, in the tunnel construction process in backfill soil, due to the low soil strength, poor tunneling conditions and complex surrounding rock stress, the self-stabilizing capability is poor after excavation disturbance, the self-stabilizing time is short, and disasters such as collapse, large deformation, overlarge ground surface settlement and the like are easy to occur in the construction process. However, due to the fact that the cognition on the engineering properties of the earth-rock mixture surrounding rock is insufficient, the unloading effect and the damage evolution mechanism of the earth-rock mixture surrounding rock are unclear in the tunnel excavation process, supporting means adopted in construction are mostly based on the past engineering experience, too much safety margin is reserved, waste is caused, and meanwhile certain potential safety hazards exist. In addition, lack of control on unloading deformation of the soil-rock mixture surrounding rock can affect the construction period and increase the cost.
Therefore, a plurality of problems are to be further researched in terms of surrounding rock unloading effect and damage evolution mechanism in the process of excavating the tunnel in the underpass under-consolidation deep and thick soil-stone mixed backfilling soil area. However, the existing research on the mechanical properties of the earth-rock mixture is mostly carried out in the form of direct shear or triaxial compression tests, and the unloading effect and the main stress steering generated by the excavation inside the surrounding rock cannot be simulated; the existing equipment for researching the unloading deformation of the tunnel surrounding rock is mainly suitable for pure soil or pure stone, is difficult to be applied to highly discrete uneven media such as soil-stone mixtures, is difficult to prepare samples, and has the defects that the soil-stone mixtures are greatly influenced by size effects and the like, and the extreme physical property difference between the soil and the stone can be further amplified by directly developing research, so that the research result has larger errors.
In view of the above, the invention is necessary to provide a test device for simulating the earth-rock mixture tunnel surrounding rock excavation unloading, and a mature sample preparation scheme is provided to prepare a saturated earth-rock mixture hollow cylindrical sample with uniform block-rock distribution and without too large pores; 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.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a simulation test device and a simulation test method for excavation unloading of a soil-rock mixture tunnel surrounding rock, and aims to solve the technical problems that in the prior art mentioned in the background art, a saturated soil-rock mixture hollow cylindrical sample with uniform block-rock distribution and no excessive large pore space is difficult to prepare, and the excavation unloading effect of the soil-rock mixture tunnel surrounding rock is difficult to simulate and reproduce really.
In order to achieve the purpose, the invention provides the following technical scheme:
a simulation test device for unloading of surrounding rock excavation of a soil-rock mixture tunnel comprises a base assembly, a combined sample loading auxiliary system, a rubber film, a strain gauge, a microcomputer-controlled electro-hydraulic servo loading system, a jacking assembly and a water pressure gauge;
the combined sample loading auxiliary system comprises a cavity assembly and a discharging assembly; the cavity assembly comprises an inner sample-containing sleeve, an outer sample-containing sleeve and a permeable stone; the inner sample sleeve and the outer sample sleeve are coaxially arranged on the base assembly, a sample loading cavity is formed between the inner sample sleeve and the outer sample sleeve, an inner pressure cavity is formed in the inner sample sleeve, and an outer pressure cavity is formed by the outer wall of the outer sample sleeve and the base assembly; the permeable stone is arranged on the base assembly and is positioned between the inner sample-containing sleeve and the outer sample-containing sleeve;
the two rubber membranes are arranged, one rubber membrane is detachably sleeved on the outer wall of the inner sample-containing sleeve, the other rubber membrane is detachably sleeved on the inner wall of the outer sample-containing sleeve, and the outer surface of the other rubber membrane is provided with the strain gauge;
the discharging assembly is detachably arranged in the sample loading cavity and can uniformly mix the rock lumps with different grain sizes and the soil when the rock lumps fall into the sample loading cavity;
after the sample is loaded in the sample loading cavity, the discharging assembly is disassembled and the jacking assembly is installed, so that the inner pressure cavity and the outer pressure cavity form a closed space respectively;
the water pressure meter is provided with a plurality of pressure sensors which can respectively measure the pressure of the space outside the two rubber films, and the jacking assembly is also provided with a closable exhaust hole;
the microcomputer control electro-hydraulic servo loading system is connected with the sample loading cavity and two closed spaces outside the sample loading cavity, and can simultaneously apply external confining pressure, internal confining pressure, axial pressure and torsional shear force to the sample loading cavity.
According to the method, the rock blocks and the soil with different particle sizes can be uniformly mixed in the sample loading cavity when falling into the sample loading cavity, namely, after the sample loading is finished, the rock of the sample in the sample loading cavity can be uniformly distributed without large pores; after the sample loading is finished, the combined sample loading auxiliary system is disassembled, the jacking assembly and the water pressure meter are installed after the sample in the rubber film is stable, and the microcomputer control electro-hydraulic servo loading system applies external confining pressure, internal confining pressure, axial pressure and torsional shearing force to the sample loading cavity, so that the excavation unloading effect of the soil-rock mixture tunnel surrounding rock is simulated and reproduced really.
Further, the base assembly comprises an instrument base, a bottom sealing disk, a rigid outer wall, and a sample base; the bottom sealing disc is arranged on the instrument base, the rigid outer wall is vertically arranged on the bottom sealing disc of the bottom sealing disc, the outer pressure cavity is formed between the rigid outer wall and the outer sample sleeve outer wall, and the top end of the rigid outer wall is detachably provided with the jacking assembly; the sample base is arranged on the bottom sealing disc, the inner sample sleeve and the outer sample sleeve are respectively coaxially arranged on the sample base, a plurality of liquid passing pipelines are arranged on the bottom sealing disc, one end of each liquid passing pipeline is connected with the microcomputer control electro-hydraulic servo loading system, the other end of each liquid passing pipeline is connected with the outer pressure cavity or penetrates through the sample base and the inner pressure cavity, and the microcomputer control electro-hydraulic servo loading system can control the water inflow of the inner pressure cavity and the outer pressure cavity.
Furthermore, the microcomputer control electro-hydraulic servo loading system comprises an external pressure servo controller, an internal pressure servo controller, a back pressure servo controller and a torsional shear controller; the external pressure servo controller is connected with the external pressure cavity through the liquid pipeline and can control the water inflow of the external pressure cavity; the internal pressure servo controller is connected with the internal pressure cavity through the liquid pipeline and can control the water inflow of the internal pressure cavity; the back pressure servo control machine penetrates through the sample base to be connected with the permeable stone and can give vertical pressure to the sample loading cavity; the torsional shear controller is connected with the sample base and can drive the sample base to rotate.
Further, the discharging assembly comprises a sample loading funnel and a material barrel; the material barrel is detachably arranged in the sample loading cavity, the plurality of hoppers are arranged and respectively arranged on the material barrel, and the hoppers are communicated with the material barrel.
Furthermore, the jacking assembly comprises a top sealing disc, a jacking plate and a counter-force frame; the top sealing disc is detachably arranged on the top end of the rigid outer wall and can abut against the top end of the sample loading cavity, and the top pressure plate is arranged on the top sealing disc and passes through the counter-force frame and the instrument base.
Furthermore, a funnel partition plate is arranged in the sample loading funnel.
Furthermore, a hoop sleeve is arranged outside the rigid outer wall.
Further, the bottom sealing disc and the sample base are respectively provided with a liquid collecting tank, and the liquid collecting tanks are communicated with the liquid through pipelines.
Furthermore, the sample loading sleeve is also provided with scales.
The invention has the beneficial effects that:
(1) according to the invention, by utilizing the combined sample loading auxiliary system and controlling the sample loading time, the rock blocks with different grain diameters and the soil are uniformly mixed when falling, no large pores exist, and the defects that the rock blocks in the sample are locally distributed and concentrated and the pores are too large in the soil-rock mixture body mechanical test are overcome.
(2) 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, the excavation unloading effect of the soil-rock mixture tunnel surrounding rock is simulated and reproduced more truly, and the damage evolution process of the soil-rock mixture surrounding rock during tunnel excavation is reflected.
(3) The invention can apply torque through a torsional shear control system to simulate the main stress steering generated in the excavation process.
(4) The invention can control the thickness of each sample loading through the scale on the sample loading sleeve when loading the sample so as to control the relative compactness of the sample.
(5) The invention can consciously adjust the particle size of the last layer of rock block filled with the sample to ensure that no large rock block is exposed on the surface and ensure the surface flatness of the sample.
(6) The invention has simple and easy-to-understand instrument principle and simple and convenient operation, can be used for conventional triaxial test after being slightly adjusted, and has higher cost performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings, which are required to be used in the embodiments, will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to actual scale.
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a schematic view of the overall structure of a combined sample loading auxiliary system;
FIG. 2 is a schematic diagram of a microcomputer controlled electro-hydraulic servo loading system and a top pressure assembly;
FIG. 3 is a schematic diagram of a combined sample loading assist system and a top view thereof;
FIG. 4 is a schematic and top plan view of the bottom sealing disk;
FIG. 5 is a schematic view of an outer sample sleeve;
FIG. 6 is a schematic view of an internal sample sleeve;
reference numerals:
1-a base assembly; 11-an instrument base; 12-bottom sealing disk; 13-a rigid outer wall; 14-a sample base; 15-liquid pipeline; 16-a sump; 17-a tightening sleeve;
2-a combined sample loading auxiliary system; 21-a cavity assembly; 211-internal sample sleeve; 212-outer sample sleeve; 213-permeable stone; 214-a sample loading chamber; 215-internal pressure chamber; 216-external pressure chamber; 22-a discharge assembly; 221-sample loading funnel; 222-a material cylinder; 223-a funnel partition;
3-rubber membrane;
4-strain gauge;
5-controlling an electro-hydraulic servo loading system by a microcomputer; 51-external pressure servo control machine; 52-internal pressure servo control machine; 53-back pressure servo control machine; 54-a torsional shear control machine;
6-a top pressing component; 61-top sealing disk; 611-exhaust holes; 62-a top pressing plate; 63-a counter-force frame;
7-water pressure meter.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
It is to be noted, however, that the appended drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention.
The embodiment provides an unloading simulation test device for surrounding rock excavation of a soil-rock mixture tunnel, which comprises a base assembly 1, a combined sample loading auxiliary system 2, a rubber film 3, a strain gauge 4, a microcomputer control electro-hydraulic servo loading system 5, a top pressure assembly 6 and a water pressure gauge 7, and is shown in figures 1-6.
This embodiment mainly divide into two stages, and first dress appearance stage, second experimental stage dismantles partial structure and installs other structures after dress appearance is accomplished to realize the experiment stage.
The base assembly 1 serves as the basis of the entire device and may in other aspects comprise in particular an instrument base 11, a bottom sealing disk 12, a rigid outer wall 13 and a sample base 14; the bottom sealing disc 12 is arranged on the instrument base 11, the rigid outer wall 13 is vertically arranged on the bottom sealing disc 12, an external pressure cavity 216 is formed between the rigid outer wall 13 and the outer wall of the external sample sleeve 212, and the top end of the rigid outer wall 13 is detachably provided with the jacking assembly 6; the sample base 14 is arranged on the bottom sealing disc 12, the inner sample sleeve 211 and the outer sample sleeve 212 are respectively and coaxially arranged on the sample base 14, a plurality of liquid through pipelines 15 are arranged on the bottom sealing disc 12, one end of each liquid through pipeline 15 is communicated with the microcomputer control electro-hydraulic servo loading system 5, the other end of each liquid through pipeline is communicated with the outer pressure cavity 216 or penetrates through the sample base 14 to be communicated with the inner pressure cavity 215, and the microcomputer control electro-hydraulic servo loading system 5 can control the water inflow of the inner pressure cavity 215 and the outer pressure cavity 216.
Firstly, the sample loading stage, please refer to fig. 1, fig. 3-fig. 6; the combined sample loading auxiliary system 2 comprises a cavity assembly 21 and a discharging assembly 22; the cavity module 21 includes an inner sample sleeve 211, an outer sample sleeve 212, and a permeable stone 213; the inner sample sleeve 211 and the outer sample sleeve 212 are coaxially provided on the base unit 1, and a sample chamber 214 is formed between the inner sample sleeve 211 and the outer sample sleeve 212, an inner pressure chamber 215 is formed in the inner sample sleeve 211, and an outer pressure chamber 216 is formed by the outer wall of the outer sample sleeve 212 and the base unit 1; the water permeable stone 213 is provided on the base module 1 and is positioned between the inner sampling sleeve 211 and the outer sampling sleeve 212. It should be understood that the loading chamber 214 is an elongated annular body and is used for loading soil and rock lumps therein.
Two rubber membranes 3 are provided, one rubber membrane 3 is detachably fitted to the outer wall of the internal sampling sleeve 211, the other rubber membrane 3 is detachably fitted to the inner wall of the external sampling sleeve 212, and a strain gauge 4 is provided on the outer surface thereof. It should be understood that the outer surface of the rubber membrane 3 is the side thereof remote from the other rubber membrane 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 is left to stand to stabilize its state.
Specifically, the inner sample sleeve 211 and the outer sample sleeve 212 are integrally assembled by four 90-degree petals, the tops of the inner sample sleeve 211 and the outer sample sleeve 212 form an inverted trapezoidal section groove, and are connected with the material barrel 222 through a connecting piece, so that rock blocks and soil fall into a sample assembling cavity 214 between the inner sample sleeve 211 and the outer sample sleeve 212 during sample assembling, and a hollow cylindrical sample is prepared. The rubber film 3 is sleeved on the outer side of the inner sample containing sleeve 211, the rubber film 3 is sleeved on the inner side of the outer sample containing sleeve 212, and the strain gauge 4 is arranged at the corresponding position. It should be understood that the rubber membrane 3 is provided on the permeable stone 213.
The discharging assembly 22 is used for placing the rock blocks and the soil into the sample loading cavity 214, the discharging assembly 22 is detachably arranged in the sample loading cavity 214, and the discharging assembly 22 can enable the rock blocks and the soil with different grain diameters to be uniformly mixed when the rock blocks and the soil fall into the sample loading cavity 214.
In other schemes, the emptying assembly 22 comprises a sample loading funnel 221 and a material barrel 222; the material cylinder 222 is detachably arranged in the sample accommodating cavity 214, a plurality of funnels are arranged on the material cylinder 222 respectively, and the funnels are communicated with the material cylinder 222. It should be understood that, during sample loading, the sample loading hoppers 221 with different heights are filled with stones and soil with different particle sizes, the stones and soil reach the sample loading cavity 214 along the annular material barrel 222, during sample loading, the upper sample loading hopper is filled with soil, the lower hopper is filled with stones, and the sizes of the stones gradually increase from top to bottom. When discharging, firstly, the soil sample at the highest position is discharged, and then the rock blocks with different grain diameters are filled in layers according to the calculated grain composition, so that the rock blocks and the soil are uniformly mixed when falling. And compacting and leveling are needed after a sample with a certain thickness is filled, and the next filling is carried out after the sample is deformed and stabilized, so that the uniform and compact sample is finally obtained. In this embodiment, three sample loading hoppers 221 are detachably provided.
After the sample loading is completed, the inner sample loading liner 211 and the outer sample loading liner 212 are removed, and after the sample is allowed to stand to stabilize, the pressing unit 6 is attached so that the inner pressure chamber 215 and the outer pressure chamber 216 form a closed space, respectively.
Referring to fig. 2-6, the water pressure gauge 7 is provided with a plurality of pressure gauges for measuring the pressure in the space outside the two rubber membranes 3, and the pressing member 6 is further provided with a closable vent hole 611. It is understood that by opening and closing the vent hole 611, the pressure of the space outside the two rubber membranes 3 after water injection, i.e., the internal and external pressures of the sample, can be adjusted, and the internal and external pressures of the sample can be read by the water pressure gauge 7.
The microcomputer control electro-hydraulic servo loading system 5 is connected with the sample loading cavity 214 and two closed spaces outside the sample loading cavity 214, and the microcomputer control electro-hydraulic servo loading system 5 can simultaneously apply external confining pressure, internal confining pressure, axial pressure and torsional shearing force to the sample loading cavity 214.
In other schemes, the microcomputer controlled electro-hydraulic servo loading system 5 comprises an external pressure servo controller 51, an internal pressure servo controller 52, a back pressure servo controller 53 and a torsional shear controller 54; the external pressure servo controller 51 is connected with the external pressure cavity 216 through the liquid pipeline 15 and can control the water inflow of the external pressure cavity 216; the internal pressure servo controller 52 is connected with the internal pressure cavity 215 through a liquid pipeline 15 and can control the water inflow of the internal pressure cavity 215; the back pressure servo control machine 53 penetrates through the sample base 14 to be connected with the permeable stone 213, and can give and control the vertical pressure of the sample containing cavity 214 by controlling the liquid entering the sample through the permeable stone 213; the torque shear control mechanism 54 is coupled to the sample base 14 and is capable of rotating the sample base 14. It will be appreciated that the torsional shear control 54 can impart a torsional shear to the sample and that the axial pressure imparted by the back pressure servo control 53 can be read through the strain gauge 4.
In other aspects, the top pressure assembly 6 comprises a top sealing disk 61, a top pressure plate 62 and a counter force frame 63; the top sealing disk 61 is detachably arranged on the top end of the rigid outer wall 13 and can abut against the top end of the sample loading cavity 214, and the top pressure plate 62 is arranged on the top sealing disk 61 and is connected with the instrument base through the counter-force frame 63. Vertical loads can be transferred to the counter frame 63 by the top plate 62. The counterforce frame 63 in this embodiment comprises a connecting rod disposed on the instrument base, a connecting plate slidably disposed on the connecting rod, and a limiting block for limiting the height position of the connecting plate, and the bottom surface of the connecting plate is connected to the top pressure plate 62.
In other schemes, a funnel partition 223 is also arranged in the sample loading funnel 221. The funnel partition 223 can ensure that the filled rock blocks and soil are uniformly distributed on the horizontal plane.
In other schemes, a tight sleeve 17 is arranged outside the rigid outer wall 13, and the deformation effect of the liquid in the outer pressure cavity 216 on the rigid outer wall can be reduced by arranging the tight sleeve 17.
In other schemes, a liquid collecting groove 16 is further respectively arranged on the bottom sealing disc 12 and the sample base 14, and the liquid collecting groove 16 is communicated with the liquid through pipeline 15.
In other schemes, scales are also arranged on the sample-loading sleeve. The thickness of each sample loading can be controlled through the scales so as to control the relative compactness of the sample.
The simulation test method of the embodiment comprises the following specific steps:
(1) assembling and combining the sample loading auxiliary system 2, firstly disassembling the reaction frame 63, installing an inner sample loading sleeve 211 and an outer sample loading sleeve 212 above the sample base 14, and placing an annular permeable stone 213 between the two sleeves;
(2) sleeving a rubber film 3 on the outer side of the internal sample-loading sleeve 211, sleeving the rubber film 3 on the inner side of the external sample-loading sleeve 212, and arranging a strain gauge 4 at a corresponding position;
(3) a material cylinder 222 and a sample loading funnel 221 are arranged above the sample loading sleeve, the outer wall of the material cylinder 222 is connected with the sample loading funnel 221, the outer wall of the material cylinder 222 is connected with the outer sample loading sleeve 212, and the inner container of the material cylinder 222 is connected with the inner sample loading sleeve 211 through a connecting piece;
(4) filling samples, namely filling different-particle-size rock blocks in sample filling hoppers 221 with different heights, wherein the rock blocks reach a sample filling cavity 214 along an annular sample filling channel, uniformly mixing the rock blocks with different particle sizes and soil during falling by controlling the sample filling time, compacting and leveling after filling a sample with a certain thickness, and filling the next time after the sample is deformed and stabilized;
(5) after the sample loading is finished, the combined sample loading auxiliary system 2 is dismantled, the internal sample loading sleeve 211 and the external sample loading sleeve 212 are dismantled, and the sample is placed still until the state of the sample is stable;
(6) installing a counter-force frame 63 and a top sealing disc 61, and calibrating the readings of the inner cavity water pressure meter 7 and the outer cavity water pressure meter 7;
(7) opening the exhaust hole 611, starting to inject liquid into the internal pressure cavity 215 and the external pressure cavity 216 through the liquid through pipeline 15, applying vertical pressure, monitoring the readings of the internal pressure, the external pressure and the axial pressure in real time in the process, stopping pressurizing after the sample reaches an initial state, closing exhaust air, and waiting for the reading to be stable;
(8) according to a pre-designed stress path, a microcomputer control electro-hydraulic servo loading system 5 is adopted to adjust the stress state of the sample to carry out a test, observe the state of the sample and record a reading;
(9) after the test is finished, the liquid in the inner pressure cavity 215 and the liquid in the outer pressure cavity 216 are completely removed through the liquid passing pipeline 15, the vertical pressure and the torque are removed, the counter-force frame 63 and the top sealing disc 61 are disassembled, the sample is removed, and the instrument is cleaned.
In the device and the method for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test, the combined sample loading auxiliary system is utilized, and the sample loading time is controlled, so that the rock blocks with different particle sizes and the soil are uniformly mixed when falling, no large pore exists, and the defects of local concentration of the rock block distribution and overlarge pore in the sample in the soil-rock mixture mechanical test are overcome. Meanwhile, the stress state of the soil-rock mixture hollow cylinder sample can be controlled through the external pressure servo control system, the internal pressure servo control system and the back pressure servo control system, the excavation unloading effect of the soil-rock mixture tunnel surrounding rock is simulated and reproduced more truly, and the damage evolution process of the soil-rock mixture surrounding rock during tunnel excavation is reflected.
The above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (10)
1. A simulation test device for unloading of surrounding rock excavation of a soil-rock mixture tunnel is characterized by comprising a base assembly, a combined sample loading auxiliary system, a rubber membrane, a strain gauge, a microcomputer-controlled electro-hydraulic servo loading system, a jacking assembly and a water pressure gauge;
the combined sample loading auxiliary system comprises a cavity assembly and a discharging assembly; the cavity assembly comprises an inner sample-containing sleeve, an outer sample-containing sleeve and a permeable stone; the inner sample sleeve and the outer sample sleeve are coaxially arranged on the base assembly, a sample loading cavity is formed between the inner sample sleeve and the outer sample sleeve, an inner pressure cavity is formed in the inner sample sleeve, and an outer pressure cavity is formed by the outer wall of the outer sample sleeve and the base assembly; the permeable stone is arranged on the base assembly and is positioned between the inner sample-containing sleeve and the outer sample-containing sleeve;
two rubber membranes are arranged, one rubber membrane is detachably sleeved on the outer wall of the inner sample-containing sleeve, the other rubber membrane is detachably sleeved on the inner wall of the outer sample-containing sleeve, and the outer surface of the other rubber membrane is provided with the strain gauge;
the discharging assembly is detachably arranged in the sample loading cavity and can uniformly mix the rock lumps with different grain sizes and the soil when the rock lumps fall into the sample loading cavity;
after the sample is filled in the sample filling cavity, disassembling the discharging assembly and installing the jacking assembly to enable the inner pressure cavity and the outer pressure cavity to form closed spaces respectively;
the water pressure meter is provided with a plurality of pressure sensors which can respectively measure the pressure of the space outside the two rubber films, and the jacking assembly is also provided with a closable exhaust hole;
the microcomputer control electro-hydraulic servo loading system is connected with the sample loading cavity and two closed spaces outside the sample loading cavity, and can simultaneously apply external confining pressure, internal confining pressure, axial pressure and torsional shear force to the sample loading cavity.
2. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test of 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 vertically arranged on the bottom sealing disc, the outer pressure cavity is formed between the rigid outer wall and the outer wall of the outer sample sleeve, and the top end of the rigid outer wall is detachably provided with the jacking assembly; the sample base is arranged on the bottom sealing disc, the inner sample sleeve and the outer sample sleeve are coaxially arranged on the sample base respectively, a plurality of liquid passing pipelines are arranged on the bottom sealing disc, one end of each liquid passing pipeline is communicated with the microcomputer control electro-hydraulic servo loading system, the other end of each liquid passing pipeline is communicated with the outer pressure cavity or penetrates through the sample base and the inner pressure cavity, and the microcomputer control electro-hydraulic servo loading system can control the water inflow of the inner pressure cavity and the outer pressure cavity.
3. The device for the unloading simulation test of the surrounding rock excavation of the soil-rock mixture tunnel according to claim 2, wherein the microcomputer-controlled electro-hydraulic servo loading system comprises an external pressure servo controller, an internal pressure servo controller, a back pressure servo controller and a torsional shear controller; the external pressure servo controller is connected with the external pressure cavity through the liquid pipeline and can control the water inflow of the external pressure cavity; the internal pressure servo controller is connected with the internal pressure cavity through the liquid pipeline and can control the water inflow of the internal pressure cavity; the back pressure servo control machine penetrates through the sample base to be connected with the permeable stone and can give vertical pressure to the sample loading cavity; the torsional shear controller is connected with the sample base and can drive the sample base to rotate.
4. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test according to claim 3, wherein the discharging assembly comprises a sample loading hopper and a material barrel; the material barrel is detachably arranged in the sample loading cavity, the plurality of hoppers are arranged on the material barrel and are respectively arranged on the material barrel, and the hoppers are communicated with the material barrel.
5. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test of claim 4, wherein the top pressure assembly comprises a top sealing disc, a top pressure plate and a counterforce frame; the top sealing disc is detachably arranged on the top end of the rigid outer wall and can abut against the top end of the sample loading cavity, and the top pressure plate is arranged on the top sealing disc and passes through the counter-force frame and the instrument base.
6. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test as claimed in claim 5, wherein a funnel partition plate is further arranged in the sample loading funnel.
7. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test as claimed in claim 6, wherein a hoop sleeve is further arranged outside the rigid outer wall.
8. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test as claimed in claim 7, wherein a liquid collecting groove is further respectively arranged on the bottom sealing disc and the sample base, and the liquid collecting groove is communicated with the liquid through pipeline.
9. The device for the soil-rock mixture tunnel surrounding rock excavation unloading simulation test as claimed in claim 8, wherein the sample loading sleeve is further provided with scales.
10. The method for simulating the unloading of the surrounding rock excavation of the soil-rock mixture tunnel utilizes the device for simulating the unloading of the surrounding rock excavation of the soil-rock mixture tunnel as claimed in any one of claims 1 to 9, and is characterized by comprising the following steps:
(1) assembling and combining the sample assembling auxiliary system, firstly disassembling the jacking assembly, installing an internal sample assembling sleeve and an external sample assembling sleeve above the sample base assembly, and placing a circular permeable stone between the two sleeves;
(2) sleeving a rubber film on the outer side of the internal sample-loading sleeve, sleeving a rubber film on the inner side of the external sample-loading sleeve, and arranging strain gauges at corresponding positions;
(3) a material discharging assembly is arranged above the internal sample loading sleeve and communicated with the internal sample loading sleeve;
(4) filling samples, namely filling different-particle-size rock blocks at different heights of the material discharging assembly, enabling the rock blocks to reach the sample filling cavity along the material discharging assembly 22, enabling the rock blocks and soil with different particle sizes to be uniformly mixed when falling through controlling the sample filling time, compacting and leveling after filling a sample with a certain thickness, and filling the next time after deformation is stable;
(5) after the sample is loaded, the combined sample loading auxiliary system is dismantled, the internal sample loading sleeve and the external sample loading sleeve 212 are dismantled, and the sample is kept still until the state of the sample is stable;
(6) installing a jacking assembly, and calibrating the readings of the inner cavity water pressure meter and the outer cavity water pressure meter;
(7) opening an exhaust hole, injecting liquid into the internal pressure cavity and the external pressure cavity through the microcomputer control electro-hydraulic servo loading system, applying vertical pressure, monitoring the internal pressure, external pressure and axial pressure reading in real time in the process, stopping pressurizing after the sample reaches an initial state, closing exhaust air, and waiting for the reading to be stable;
(8) according to a pre-designed stress path, a microcomputer control electro-hydraulic servo loading system is adopted to adjust the stress state of the sample to carry out a test, observe the state of the sample and record a reading;
(9) after the test is finished, the liquid in the inner pressure cavity and the liquid in the outer pressure cavity are completely removed, the vertical pressure and the torque are removed, the jacking assembly is disassembled, the sample is disassembled, and the instrument is cleaned.
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