CN113720995A - Centrifugal test device for reinforcing influence of side foundation pit excavation on periphery of existing tunnel hole - Google Patents
Centrifugal test device for reinforcing influence of side foundation pit excavation on periphery of existing tunnel hole Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 53
- 238000009412 basement excavation Methods 0.000 title claims abstract description 43
- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 7
- 238000004088 simulation Methods 0.000 claims abstract description 54
- 239000002689 soil Substances 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 21
- 230000002787 reinforcement Effects 0.000 claims abstract description 20
- 238000001514 detection method Methods 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims description 74
- 238000006073 displacement reaction Methods 0.000 claims description 20
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 20
- 238000005452 bending Methods 0.000 claims description 11
- 235000005074 zinc chloride Nutrition 0.000 claims description 10
- 239000011592 zinc chloride Substances 0.000 claims description 10
- 239000004576 sand Substances 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 7
- 239000011083 cement mortar Substances 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 claims description 3
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- 238000003466 welding Methods 0.000 claims description 3
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- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 4
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- 238000011161 development Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000005336 cracking Methods 0.000 description 1
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a centrifugal test device for the influence of side foundation pit excavation on the reinforcement of the periphery of an existing tunnel hole, which comprises a test box body, a tunnel hole periphery reinforcement simulation system, a foundation pit excavation simulation system and a centrifuge data acquisition system, wherein a sandy soil foundation is filled in the test box body, and the tunnel hole periphery reinforcement simulation system and the foundation pit excavation simulation system are both embedded in the sandy soil foundation; detecting instruments are arranged around the tunnel model and connected with a centrifuge data acquisition system; after the foundation pit excavation simulation system is started, detecting instruments around the tunnel hole reinforcing simulation system detect relevant data and send the data to the centrifuge data acquisition system, and the centrifuge data acquisition system acquires signals of all sensors. The invention has the beneficial effects that: the invention designs a simulation entity, obtains the stress information of the stratum and the side tunnel in the excavation process of the foundation pit through the field detection of the sensor, provides a beneficial reference for the existing tunnel grouting deformation control technology under the excavation condition of the side foundation pit, and has high accuracy.
Description
Technical Field
The invention relates to a tunnel construction technology, in particular to a centrifugal test device for the influence of side foundation pit excavation on the reinforcement of the periphery of an existing tunnel hole.
Background
With the rapid development of the traffic basic engineering in China, a large number of foundation pit projects are generated in the engineering construction process, the scale and the depth of the foundation pits are continuously increased, and meanwhile, the working condition of carrying out foundation pit excavation on the adjacent existing tunnel is also continuously increased. The unloading of the excavation of the foundation pit influences the internal force and the deformation of the adjacent subway tunnel. Under the influence of excavation of a deep and large foundation pit adjacent to a tunnel in a certain interval of a subway line in a certain city, tunnel segments are damaged by cracking, leakage and the like, and the structural safety and the service performance of the subway tunnel are seriously threatened. Therefore, the research on the deformation response rule of the excavation and unloading of the side foundation pit on the adjacent tunnel structure has important significance for evaluating the tunnel safety and providing effective control measures.
With the development of scientific technology and test means, physical model tests gradually become one of the important means of scientific research in the field of geotechnical engineering, and common methods include normal gravity scale tests, in-situ tests and super-gravity centrifugal model tests. The centrifugal model test provides a supergravity environment through centrifugal acceleration, restores a soil body in-situ stress field under a geometric scale reduction condition of the model, and is widely applied to the field of geotechnical engineering research at present. However, the dynamic process of geotechnical engineering cannot be simulated manually in the existing centrifuge test, and the design of related mechanical devices is expensive. Therefore, a method for simulating the dynamic process of excavation of a foundation pit, which is economical and practical, is needed.
The existing tunnel protection measures under the common excavation condition of the side foundation pit in engineering practice comprise grouting reinforcement around the tunnel, isolation piles, pit bottom stratum reinforcement and the like. However, the research on the effectiveness and action mechanism of the measures mainly focuses on numerical simulation, and the field monitoring data is very limited. Therefore, it is very necessary to develop a centrifugal test device and method for existing tunnel protection measures under the excavation condition of the side foundation pit.
Disclosure of Invention
The invention aims to provide a centrifugal test device for the influence of excavation of a side foundation pit on reinforcement of the periphery of an existing tunnel, which is subjected to physical simulation and can be detected on site, aiming at the defects of the prior art.
The technical scheme adopted by the invention is as follows: a centrifugal test device for influencing the reinforcement of side foundation pit excavation on the periphery of an existing tunnel hole comprises a test box body, a tunnel hole periphery reinforcement simulation system, a foundation pit excavation simulation system and a centrifuge data acquisition system, wherein a sandy soil foundation is filled in the test box body, and the tunnel hole periphery reinforcement simulation system and the foundation pit excavation simulation system are both embedded in the sandy soil foundation; detecting instruments are arranged around the tunnel model and connected with a centrifuge data acquisition system; after the foundation pit excavation simulation system is started, the detection instruments around the tunnel hole reinforcing simulation system detect relevant data and send the data to the centrifuge data acquisition system, and the centrifuge data acquisition system acquires signals of the sensors and transmits the signals to the computer for subsequent analysis and calculation.
According to the scheme, the tunnel hole periphery reinforcement simulation system comprises a tunnel main body and a plurality of prefabricated cylinders, wherein the tunnel main body is made of aluminum pipes, the tunnel main body is horizontally embedded in a sandy soil foundation of the test box body, and the axis of the tunnel main body is parallel to one side edge of the test box body; a plurality of prefabricated cylinders are circumferentially arranged at intervals in the middle of the tunnel main body, and the distance between the prefabricated cylinders is adjusted according to working conditions.
According to the scheme, the prefabricated cylinder is prefabricated by cement mortar, a fixing bolt is embedded in the prefabricated cylinder along the axis direction, the end part of the fixing bolt extends out and is inserted into a preformed hole of the tunnel main body to be matched and connected with a nut on the inner side; and the axis of the tunnel main body is vertical to the axis of each embedded cylinder.
According to the scheme, a plurality of strain gauges are adhered to the outer wall of the tunnel main body, and part of the strain gauges and the prefabricated cylinder are alternately arranged; arranging a plurality of bending elements in the sandy soil foundation above the tunnel main body, wherein the bending elements are arranged at intervals in a direction vertical to the axis of the tunnel main body; the method comprises the following steps that a plurality of differential displacement sensors and a plurality of laser displacement sensors are arranged on the surface of a sandy soil foundation above a tunnel main body, wherein the differential displacement sensors are positioned right above the tunnel main body and are arranged at intervals along the axial direction of the tunnel main body; the laser displacement sensors are arranged at intervals along a direction perpendicular to the axis of the tunnel body; each strain gauge, each bending element and each displacement sensor are respectively connected with a centrifuge data acquisition system.
According to the scheme, the foundation pit excavation simulation system comprises a surrounding wall simulation body, a drainage pipe and a drainage box; the enclosure wall simulation body is fixedly installed in the sand foundation, and the elevation of the inner bottom of the enclosure wall simulation body is consistent with the elevation of the inner bottom of the tunnel main body; a rubber layer is arranged in the enclosure wall simulator body and encloses a heavy liquid cavity, heavy liquid with the same density as the soil body to be excavated in the foundation pit is poured in the heavy liquid cavity, and the height of the heavy liquid is consistent with the excavation depth; the bottom of the heavy liquid cavity is provided with a pore pressure meter connected with a centrifuge data acquisition system; the heavy liquid cavity is connected with a liquid discharge box through a liquid discharge pipe, and the liquid discharge pipe is provided with a valve, a solenoid valve and a flow rate control valve.
According to the scheme, the rubber bag enclosing the heavy liquid cavity is made of a rubber film with light weight, small rigidity and thin thickness; the bottom of the rubber bag is connected with the liquid discharge pipe through a waterproof joint, and the rubber bag is fixed with the enclosure wall simulation body through a clamp.
According to the scheme, the enclosure wall simulation body is of a rectangular structure, and one side edge of the enclosure wall simulation body is parallel to the axis of the tunnel main body.
According to the scheme, the liquid discharging box is formed by welding a plurality of aluminum plates in a surrounding mode, a liquid inlet and a gas outlet are formed in the liquid discharging box respectively, and the liquid inlet is connected with the heavy liquid cavity through a liquid discharging pipe; the air outlet extends to the outside of the test box body through a connected air pipe, so that the internal and external pressure difference is balanced, and heavy liquid is convenient to drain.
According to the scheme, the test box body is a rectangular box body and is made of rigid materials.
According to the scheme, the heavy liquid is a zinc chloride solution.
The invention has the beneficial effects that: the method comprises the steps of designing a simulation entity, and combining a tunnel model main body and a prefabricated cylinder into an integral simulation tunnel around-hole grouting; simulating a foundation pit excavation process in an excavation range by using a heavy liquid cavity and a heavy liquid drainage system, carrying out field detection by using sensors such as a strain gauge, a soil pressure gauge, a bending element, an LVDT (linear variable differential transformer), a laser displacement meter and the like, acquiring stress information of a stratum and a side tunnel in the foundation pit excavation process, calculating and analyzing a mechanical law, and providing a beneficial reference for an existing tunnel grouting deformation control technology under the excavation condition of the side foundation pit; compared with the pure numerical simulation, the entity simulation test can more dynamically and objectively reflect the specific construction process, and has high accuracy. The invention has simple structure, low design cost and simple and convenient operation process.
Drawings
Fig. 1 is a schematic layout of an embodiment of the present invention.
Fig. 2 is a top view of the present embodiment.
Fig. 3 is a cross-sectional view of the tunnel hole reinforcement simulation system in this embodiment.
In the figure: 1. a test box body; 2. a tunnel body; 3. prefabricating a cylinder; 4. a containment wall simulator; 5. a rubber bag; 6. an electromagnetic valve; 7. a flow rate control valve; 8. a liquid discharge tank; 9. a sandy soil foundation; 10. a liquid discharge pipe; 11. a waterproof joint; 12. heavy zinc chloride solution; 13. a strain gauge; 14. a soil pressure gauge; 15. a bending element; 16. a laser displacement sensor; 17. a differential displacement sensor; 18. a pore pressure meter; 19. centrifuge data acquisition system.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
The centrifugal test device for the influence of side foundation pit excavation on the existing tunnel hole periphery reinforcement shown in the figures 1-2 comprises a test box body 1, a tunnel hole periphery reinforcement simulation system, a foundation pit excavation simulation system and a centrifuge data acquisition system 19, wherein a sandy soil foundation 9 is filled in the test box body 1, and the tunnel hole periphery reinforcement simulation system and the foundation pit excavation simulation system are both buried in the sandy soil foundation; detecting instruments are arranged around the tunnel model and connected with a centrifuge data acquisition system 19; after the foundation pit excavation simulation system is started, the detection instruments around the tunnel hole reinforcing simulation system detect relevant data and send the data to the centrifuge data acquisition system 19, and the centrifuge data acquisition system 19 obtains signals of the sensors and transmits the signals to the computer for subsequent analysis and calculation.
Preferably, the test box 1 is a rectangular box and is made of rigid materials.
Preferably, as shown in fig. 3, the tunnel hole periphery reinforcement simulation system comprises a tunnel main body 2 made of thin-wall aluminum tubes and a plurality of prefabricated cylinders 3, wherein the tunnel main body 2 is horizontally embedded in a sandy soil foundation 9 of the test box body 1, and the axis of the tunnel main body 2 is parallel to one side edge of the test box body 1; a plurality of prefabricated cylinders 3 are circumferentially arranged on the tunnel main body 2 at intervals, and the distance between the prefabricated cylinders 3 can be adjusted according to working conditions; the prefabricated cylinder 3 is prefabricated by cement mortar, a fixing bolt is embedded in the prefabricated cylinder along the axis direction, the end part of the fixing bolt extends out and is inserted into a preformed hole of the tunnel main body 2 to be connected with a nut on the inner side in a matching mode. In this embodiment, the axis of the tunnel main body 2 is perpendicular to the axis of the embedded cylinder.
Preferably, a plurality of strain gauges 13 are adhered to the outer wall of the tunnel body 2, and part of the strain gauges 13 are alternately arranged with the prefabricated cylinder 3. A plurality of bending elements 15 are arranged in the sandy soil foundation 9 above the tunnel main body 2, and the plurality of bending elements 15 are arranged at intervals along the direction vertical to the axis of the tunnel main body 2. A plurality of differential displacement sensors (LVDT)17 and a plurality of laser displacement sensors 16 are arranged on the surface of the sand foundation 9 above the tunnel main body 2, wherein the differential displacement sensors 17 are positioned right above the tunnel main body 2 and are arranged at intervals along the axial direction of the tunnel main body 2; the laser displacement sensors 16 are arranged at intervals along the direction vertical to the axis of the tunnel body 2; each strain gauge 13, flexure element 15 and each displacement sensor are connected to a centrifuge data acquisition system 19.
Preferably, the foundation pit excavation simulation system comprises a containment wall simulation body 4, a drainage pipe 10 and a drainage box 8; the enclosure wall simulator 4 is fixedly installed in a sandy soil foundation 9, and the elevation of the inner bottom of the enclosure wall simulator is consistent with the elevation of the inner bottom of the tunnel main body 2; a rubber layer is arranged in the enclosure wall simulator 4 and encloses a heavy liquid cavity, heavy liquid with the same density as the soil body to be excavated in the foundation pit is poured in the heavy liquid cavity, and the height of the heavy liquid is consistent with the excavation depth (the height of the heavy liquid is consistent with the height of foundation soil outside the foundation pit); the bottom of the heavy liquid cavity is provided with a pore pressure meter 18 connected with a centrifuge data acquisition system 19; the heavy liquid cavity is connected with a liquid discharge box 8 through a liquid discharge pipe 10, and the liquid discharge pipe 10 is provided with a valve, specifically an electromagnetic valve 6 and a flow rate control valve 7; the heavy liquid is zinc chloride (ZnCl)2) And (3) solution. After the electromagnetic valve 6 on the drainage pipe 10 is powered on and opened, the heavy zinc chloride solution 12 finally enters the drainage box 8 through the electromagnetic valve 6 and the flow rate control valve 7 on the drainage pipe 10, and after all the heavy zinc chloride solution 12 is collected in the drainage box 8, the foundation pit excavation process is simulated and completed. The invention discharges heavy liquid based on pressure difference, and requires that the height of a valve opening is lower than the lowest height of the heavy liquid.
In the embodiment, the rubber bag 5 enclosing the heavy liquid cavity is made of a rubber film with light weight, small rigidity and thin thickness, so that the influence of the rubber bag on the foundation soil is reduced as much as possible on the premise of ensuring waterproofness; the bottom of the rubber bag 5 is communicated withThe waterproof joint 11 is connected with the liquid discharge pipe 10, and the rubber bag 5 and the enclosure wall simulation body 4 are fixed through a clamp. The enclosure wall simulation body 4 is of a rectangular structure, and one side edge of the enclosure wall simulation body is parallel to the axis of the tunnel main body 2. The heavy liquid is zinc chloride (ZnCl)2) The solution and zinc chloride powder are very soluble in water at normal temperature, and the density of the solution is greatly changed along with the change of the mass of the solute, so that different foundation soil densities can be conveniently simulated; zinc chloride (ZnCl)2) Has strong corrosivity, and is ventilated and protected in the preparation process. The electromagnetic valve 6 is an electrified ball valve, and functions of opening and closing the valve, feeding back information and the like can be realized according to different wiring schemes. The flow rate control valve 7 is used for controlling the flow rate of liquid in the pipeline, and the construction progress of the foundation pit soil body on site is simulated by combining the size of the foundation pit model and the design of centrifugal acceleration. The liquid discharge box 8 is formed by welding a plurality of aluminum plates in an enclosing manner, a liquid inlet and a gas outlet are respectively formed in the liquid discharge box 8, the liquid inlet is connected with a single through after being tapped, a raw material belt is wound, and the outer side of the liquid discharge box is subjected to oil sludge leakage stoppage; the liquid inlet is connected with the heavy liquid cavity through a liquid discharge pipe 10; the air outlet is connected with the single-way pipe after being tapped, the thread seal strip is wound, oil sludge is leaked outside, the air outlet extends to the outside of the test box body 1 through the connected air pipe, the internal and external pressure difference is balanced, and heavy liquid drainage is facilitated.
The specific construction process of the embodiment is as follows: prefabricating the prefabricated cylinder 3 by using cement mortar, and embedding a fixing screw rod in the prefabricated cylinder 3; designing a tunnel main body 2 by using a thin-wall aluminum pipe, adhering a strain gauge 13 on the surface of the tunnel main body 2, drilling a reserved hole, and connecting and fixing a fixing screw rod in a prefabricated cylinder 3 through an inner nut; calibrating sensors required by relevant tests, such as a bending element 15, a pore pressure gauge 18, a soil pressure gauge 14 and the like, pre-buried at relevant positions and installing; the liquid discharge box 8 is connected with a liquid discharge pipe 10 and then embedded at the bottom of the test box body 1; preparing a sandy soil foundation 9 model by a sand rain method, and setting a reasonable height to control the density of the sandy soil model; laying the sand foundation 9 to a corresponding height, and placing the tunnel main body 2, the enclosure wall simulation body 4 and the sensors; continuing the sand rain method to prepare the sand foundation 9 to a preset stratum height (the upper opening of the model enclosure wall is higher than the upper surface of the sand foundation 9); a rubber bag 5 is fixed in the enclosure wall simulation body 4, and the bottom opening is connected with a liquid discharge pipe 10 through a waterproof joint 11; preparing heavy zinc chloride solution 12 to make the density of the heavy solution consistent with that of the soil body excavated in the foundation pit; and (3) filling heavy liquid into the rubber bag 5, wherein the height of the heavy liquid is consistent with that of the foundation soil outside the foundation pit.
According to the method, relevant parts of the tunnel hole periphery grouting reinforcement system and the foundation pit excavation simulation system are subjected to test design according to actual engineering design parameters and a model scaling scale. After the whole centrifugal test device is assembled, the centrifugal test device is placed into a centrifuge for testing. After the centrifuge is operated, the rotating speed is stably increased, and the sensor can be obviously changed at the moment, wherein the change is caused by gradual acceleration of the centrifuge. After a predetermined acceleration is reached, the sensor readings will gradually stabilize. The actual foundation pit excavation process is simulated by controlling the electromagnetic valve to discharge liquid, in the process, the structure and the surrounding soil body can change along with the change, and the sensors are arranged to monitor the dynamic changes of the physical and mechanical parameters in real time, such as the soil pressure gauge 14 for monitoring the soil pressure change, the pore pressure gauge 18 for monitoring the pore water pressure change, the differential displacement sensor 17 and the laser displacement sensor 16 for monitoring the structure deformation and the surface subsidence, and the strain gauge for monitoring the structure model deformation. Through the combined action of the sensors, the influence of the foundation pit excavation engineering on surrounding soil bodies and structures is analyzed. The maximum settlement point and the structural deformation are predicted, so that protective measures can be made pertinently and safety construction is guided.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the embodiments, it will be apparent to those skilled in the art that modifications can be made to the technical solutions described in the above-mentioned embodiments, or equivalent substitutions of some technical features, but any modifications, equivalents, improvements and the like within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims (10)
1. A centrifugal test device for influencing the reinforcement of side foundation pit excavation on the periphery of an existing tunnel hole is characterized by comprising a test box body, a tunnel hole periphery reinforcement simulation system, a foundation pit excavation simulation system and a centrifuge data acquisition system, wherein a sandy soil foundation is filled in the test box body, and the tunnel hole periphery reinforcement simulation system and the foundation pit excavation simulation system are both embedded in the sandy soil foundation; detecting instruments are arranged around the tunnel model and connected with a centrifuge data acquisition system; after the foundation pit excavation simulation system is started, the detection instruments around the tunnel hole reinforcing simulation system detect relevant data and send the data to the centrifuge data acquisition system, and the centrifuge data acquisition system acquires signals of the sensors and transmits the signals to the computer for subsequent analysis and calculation.
2. The centrifugal test device according to claim 1, wherein the tunnel hole periphery reinforcing simulation system comprises a tunnel main body made of aluminum pipes and a plurality of prefabricated cylinders, the tunnel main body is horizontally embedded in a sandy soil foundation of the test box body, and the axis of the tunnel main body is parallel to one side edge of the test box body; a plurality of prefabricated cylinders are circumferentially arranged at intervals in the middle of the tunnel main body, and the distance between the prefabricated cylinders is adjusted according to working conditions.
3. The centrifugal test device according to claim 2, wherein the prefabricated cylinder is prefabricated by cement mortar, a fixing bolt is embedded in the prefabricated cylinder along the axial direction, the end of the fixing bolt extends out, and the fixing bolt is inserted into a preformed hole of the tunnel main body and is matched and connected with a nut on the inner side; and the axis of the tunnel main body is vertical to the axis of each embedded cylinder.
4. A centrifugal test apparatus according to claim 2, wherein a plurality of strain gauges are adhered to the outer wall of the tunnel body, and part of the strain gauges are alternately arranged with the prefabricated cylinder; arranging a plurality of bending elements in the sandy soil foundation above the tunnel main body, wherein the bending elements are arranged at intervals in a direction vertical to the axis of the tunnel main body; the method comprises the following steps that a plurality of differential displacement sensors and a plurality of laser displacement sensors are arranged on the surface of a sandy soil foundation above a tunnel main body, wherein the differential displacement sensors are positioned right above the tunnel main body and are arranged at intervals along the axial direction of the tunnel main body; the laser displacement sensors are arranged at intervals along a direction perpendicular to the axis of the tunnel body; each strain gauge, each bending element and each displacement sensor are respectively connected with a centrifuge data acquisition system.
5. The centrifugal test apparatus according to claim 1, wherein the foundation pit excavation simulation system includes a containment wall simulator, a drain pipe, and a drain tank; the enclosure wall simulation body is fixedly installed in the sand foundation, and the elevation of the inner bottom of the enclosure wall simulation body is consistent with the elevation of the inner bottom of the tunnel main body; a rubber layer is arranged in the enclosure wall simulator body and encloses a heavy liquid cavity, heavy liquid with the same density as the soil body to be excavated in the foundation pit is poured in the heavy liquid cavity, and the height of the heavy liquid is consistent with the excavation depth; the bottom of the heavy liquid cavity is provided with a pore pressure meter connected with a centrifuge data acquisition system; the heavy liquid cavity is connected with a liquid discharge box through a liquid discharge pipe, and the liquid discharge pipe is provided with a valve, a solenoid valve and a flow rate control valve.
6. A centrifugal test device according to claim 5, wherein the rubber bag enclosing the heavy liquid chamber is made of a rubber film having light weight, low rigidity and thin thickness; the bottom of the rubber bag is connected with the liquid discharge pipe through a waterproof joint, and the rubber bag is fixed with the enclosure wall simulation body through a clamp.
7. A centrifugal test device according to claim 5, wherein the enclosure wall analogue body is of a rectangular configuration with one side parallel to the axis of the tunnel body.
8. The centrifugal test device according to claim 5, wherein the liquid discharge box is formed by welding a plurality of aluminum plates in an enclosing manner, a liquid inlet and a gas outlet are respectively formed in the liquid discharge box, and the liquid inlet is connected with the heavy liquid cavity through a liquid discharge pipe; the air outlet extends to the outside of the test box body through a connected air pipe, so that the internal and external pressure difference is balanced, and heavy liquid is convenient to drain.
9. A centrifugal test apparatus according to claim 1, wherein the test chamber is a rectangular chamber made of a rigid material.
10. A centrifugal test device according to claim 5, wherein the heavy liquid is a zinc chloride solution.
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| CN202110930884.0A CN113720995B (en) | 2021-08-13 | 2021-08-13 | Centrifugal test device for reinforcing influence of side pit excavation on circumference of existing tunnel |
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| CN202110930884.0A CN113720995B (en) | 2021-08-13 | 2021-08-13 | Centrifugal test device for reinforcing influence of side pit excavation on circumference of existing tunnel |
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| CN114482150A (en) * | 2022-01-25 | 2022-05-13 | 浙江工业大学 | Test device for simulating influence and active control of foundation pit excavation adopting supporting servo system on tunnel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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