CN112816660A - Centrifugal model test device and method for researching underground continuous wall construction environmental effect - Google Patents
Centrifugal model test device and method for researching underground continuous wall construction environmental effect Download PDFInfo
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- CN112816660A CN112816660A CN202110048289.4A CN202110048289A CN112816660A CN 112816660 A CN112816660 A CN 112816660A CN 202110048289 A CN202110048289 A CN 202110048289A CN 112816660 A CN112816660 A CN 112816660A
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- 238000010276 construction Methods 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 57
- 230000007613 environmental effect Effects 0.000 title claims abstract description 43
- 238000012360 testing method Methods 0.000 title claims abstract description 27
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 136
- 239000002689 soil Substances 0.000 claims abstract description 128
- 239000007788 liquid Substances 0.000 claims abstract description 113
- 239000011780 sodium chloride Substances 0.000 claims abstract description 71
- 230000008569 process Effects 0.000 claims abstract description 34
- 230000000694 effects Effects 0.000 claims abstract description 28
- 230000001276 controlling effect Effects 0.000 claims abstract description 15
- 239000002002 slurry Substances 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims abstract description 11
- 230000001105 regulatory effect Effects 0.000 claims abstract description 9
- 238000010998 test method Methods 0.000 claims abstract description 5
- 239000003292 glue Substances 0.000 claims description 93
- 239000004816 latex Substances 0.000 claims description 86
- 229920000126 latex Polymers 0.000 claims description 86
- 239000002699 waste material Substances 0.000 claims description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 36
- 239000011148 porous material Substances 0.000 claims description 35
- 238000003860 storage Methods 0.000 claims description 32
- 238000006073 displacement reaction Methods 0.000 claims description 22
- 238000007599 discharging Methods 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 19
- 239000010935 stainless steel Substances 0.000 claims description 19
- 229910001220 stainless steel Inorganic materials 0.000 claims description 19
- 238000004088 simulation Methods 0.000 claims description 17
- 238000005259 measurement Methods 0.000 claims description 14
- 239000004576 sand Substances 0.000 claims description 13
- 239000002985 plastic film Substances 0.000 claims description 11
- 238000009412 basement excavation Methods 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 9
- 229910000838 Al alloy Inorganic materials 0.000 claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 7
- 238000005452 bending Methods 0.000 claims description 7
- 239000010959 steel Substances 0.000 claims description 7
- 239000004567 concrete Substances 0.000 claims description 5
- 230000005484 gravity Effects 0.000 claims description 4
- 239000012528 membrane Substances 0.000 claims description 4
- 239000004094 surface-active agent Substances 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 229920001971 elastomer Polymers 0.000 claims description 2
- 238000005429 filling process Methods 0.000 claims description 2
- 230000003068 static effect Effects 0.000 claims description 2
- 238000003466 welding Methods 0.000 claims description 2
- 238000003754 machining Methods 0.000 claims 1
- 239000002245 particle Substances 0.000 claims 1
- 239000004033 plastic Substances 0.000 claims 1
- 230000007246 mechanism Effects 0.000 abstract description 4
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 abstract description 4
- 239000011592 zinc chloride Substances 0.000 abstract description 2
- 235000005074 zinc chloride Nutrition 0.000 abstract description 2
- 238000011160 research Methods 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 239000011150 reinforced concrete Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
Abstract
The invention discloses a centrifugal model test device and a centrifugal model test method for researching the construction environmental effect of an underground continuous wall. The test device can be used for researching the influence effect of the underground continuous wall construction on the surrounding stratum and the mechanical behavior of the adjacent shallow buried pipeline or the shield tunnel and the internal mechanism thereof. The sodium chloride solution is adopted to simulate the slurry adopted in the grooving construction process of the underground diaphragm wall, so that the method has the advantages of easily available materials, low price, environmental protection, convenient heavy control, safety, harmlessness and the like, and effectively avoids the problem of strong corrosivity when the zinc chloride solution is used; the invention can conveniently and accurately reproduce the initial ground stress applied to the groove position of the underground continuous wall before the underground continuous wall is excavated or simulate the soil pressure unloading effect in the grooving construction process of the underground continuous wall by regulating and controlling the height of the liquid level of the sodium chloride solution exceeding the surface of the model soil or being flush with the surface of the model soil.
Description
Technical Field
The invention belongs to the field of deep foundation pit engineering, and particularly relates to a centrifugal model test device and method for researching the construction environmental effect of an underground continuous wall.
Background
The underground diaphragm wall technology has been widely applied and developed to a certain extent since the 20 th century and the 50 th century are introduced into the field of deep foundation pit engineering in China. The Chinese invention patent (granted publication No. CN110158575B) discloses a construction method of an underground diaphragm wall, which has the advantages of few construction joints and low leakage occurrence probability. Chinese utility model patent (granted publication No. CN211948373U) discloses a prefabricated underground continuous wall joint structure, which has the advantages of simple integral structure and convenient operation. The Chinese invention patent (application publication No. CN111827267A) discloses a construction method of an underground diaphragm wall, which has the advantages of short construction period, small adverse effect on construction and the like.
The underground continuous wall can be used as a deep foundation pit enclosure structure, and also can be used as a box foundation or a basement outer wall permanent structure bearing the vertical load of an upper structure. When the underground continuous wall is used as a deep foundation pit enclosure structure, compared with other types of enclosure structures, the underground continuous wall has the advantages of good integrity, high rigidity, high waterproof performance, wide applicable geological conditions and the like. Therefore, the underground continuous wall enclosure structure is widely applied to coastal soft soil areas in China. When the underground diaphragm wall is applied to deep foundation pit engineering in dense areas of urban buildings, the grooving construction and subsequent foundation pit excavation of the underground diaphragm wall can generate certain adverse effects on the safety and stability of buildings, underground pipelines, municipal roads, pile foundations, tunnels and other infrastructure at the periphery of a site. The accurate measurement of the influence effect is the basis for implementing protection measures and optimizing the design and construction process of the building envelope, and becomes one of the most important research subjects in the field of deep foundation pit engineering.
At present, the research on the influence effect of foundation pit excavation on the surrounding environment is sufficient. The Chinese invention patent (application publication No. CN110727985A) discloses a method for predicting the vertical deformation of an existing subway tunnel near a foundation pit project. The utility model discloses a chinese utility model patent (grant publication number CN211172116U) discloses a test device of simulation foundation ditch excavation to closing on building foundation pile bearing capacity influence. The Chinese invention patent (application publication number CN109555170A) discloses an indoor simulation device and method for influence of foundation pit excavation on deformation of a large-chassis multi-tower building. However, the research on the environmental effect of underground continuous wall construction is still relatively deficient, and the existing research mainly adopts numerical simulation or actual measurement and analysis means. The actual measurement results show that the stratum deformation caused in the grooving construction stage of the underground diaphragm wall can be as high as 40-50% of the total deformation of foundation pit excavation, and the building settlement can be caused to be not negligible. The existing numerical simulation results show that the length of the groove section of the underground continuous wall is the factor which has the greatest influence on the reduction of the formation displacement and the horizontal stress induced by the construction of the underground continuous wall.
Numerical simulation and actual measurement analysis are important means for researching the construction environmental effect of the underground continuous wall, but have certain defects. For example, numerical simulation often requires many assumptions and simplifications on the actual situation, and the results also require verification; the actual measurement analysis only aims at specific geological conditions or local areas generally, is lack of universality, and results of the actual measurement analysis are generated under the coupling of various factors, so that quantitative judgment can not be made on the mechanism of the construction environmental effect of the underground continuous wall. Therefore, it is necessary to develop a centrifugal model test study of the underground continuous wall construction environmental effect, and to further clarify the mechanism of the underground continuous wall construction environmental effect, so as to provide a theoretical basis for the structure optimization and the construction process optimization of the underground continuous wall and the protection of surrounding buildings. However, because the construction processes of underground continuous wall slurry retaining wall excavation, concrete pouring and the like are difficult to simulate in the centrifugal model test, the research of the underground continuous wall construction on the stratum displacement and the response of the adjacent shallow buried pipeline or the shield tunnel by adopting the centrifugal model test means is not reported temporarily.
Disclosure of Invention
The invention provides a centrifugal model test device and a centrifugal model test method for researching the construction environment effect of an underground continuous wall, which can be used for researching the influence effect of the underground continuous wall construction on the surrounding stratum and the mechanical behavior of an adjacent shallow buried pipeline or a shield tunnel and the internal mechanism of the effect.
The invention adopts the following technical scheme:
a centrifugal model test device and method for researching the construction environmental effect of an underground continuous wall comprise a model box, model soil, a model tunnel, an underground continuous wall construction simulation system and an environmental effect measurement system.
The model box comprises a box body and an auxiliary top plate; the box body is formed by welding high-strength aluminum alloy plates (the tensile strength is more than 500MPa), and stiffening plates are arranged on the outer surfaces of the aluminum alloy plates and used for reducing the thickness of the aluminum alloy plates and reducing the deformation of the box body in the test process; the bottom of the box body is provided with drain holes which are uniformly distributed and drain pipes which are communicated with the inside and the outside and are used for being connected with a bucket filled with water, so that the model soil is saturated by injecting water into the model soil; the auxiliary top plate is connected with the top surface of the box body through bolts and is used for providing a support carrier for the underground continuous wall construction simulation system and the environmental effect measurement system.
The model soil is filled in the model box, and the filling height is lower than the height of the box body; the model soil is saturated sandy soil, and the average grain diameter of the model soil is 80-160 mu m.
The model tunnel is embedded in model soil and is formed by processing an organic glass tube at one time; the axial direction of the model tunnel is parallel to the extending direction of the model underground continuous wall groove; the clear distance between the model tunnel and the inner wall of the box body parallel to the axial direction of the model tunnel is more than 2 times of the outer diameter of the model tunnel.
The underground continuous wall construction simulation system comprises a model underground continuous wall groove, a model guide wall, a latex film, a temporary template, a hopper, a connector, a fixing rod, a fixing block, a glue storage tank, a waste liquid collector, a first normally-closed electromagnetic valve, a first flow control valve, a second normally-closed electromagnetic valve, a third flow control valve, a ball valve, a glue discharge pipe, a waste liquid collection pipe, a discharge pipe, thread locking glue, an activated sand-stainless steel powder mixture, a sodium chloride solution and a groove bottom micro pore pressure meter;
embedding the model underground continuous wall groove into model soil, wherein the bottom surface of the model underground continuous wall groove is parallel to a horizontal plane, and the side surface of the model underground continuous wall groove is vertical to the horizontal plane;
the model guide wall is tightly attached to the side surface of the model underground continuous wall groove within the range from the top to the lower 20mm, and the model guide wall is made of an aluminum alloy plate;
the latex film is tightly attached to the inner wall of the groove of the model underground continuous wall; the plane size of the latex film is the same as that of the groove of the model underground continuous wall, and the height of the latex film is greater than the depth of the groove of the model underground continuous wall;
the temporary template is used for supporting the latex film in the model soil filling process and reserving a geometric space of the model underground continuous wall groove; the bottom of the temporary template is provided with a liquid discharge hole, and the top of the temporary template is connected with the connector;
the hopper is fixed on the auxiliary top plate of the model box at a position corresponding to the groove of the model underground continuous wall through a fixing block, and the bottom of the hopper is connected with the latex film through a connector;
the connector is a double-layer steel sheet with a hole, and the steel sheets are connected through a bolt;
the fixing rod is a threaded steel rod and is used for fixing the connector at a preset position on the auxiliary top plate of the model box;
the fixed blocks are positioned at two ends of the glue storage tank and the hopper and are used for preventing the glue storage tank and the hopper from shaking left and right in the rotation process of the centrifugal machine;
the glue storage box is fixed on the auxiliary top plate of the model box through bolts and is used for storing thread locking glue for simulating a cast-in-place concrete cementing material;
the waste liquid collector is a square steel container, is fixed at the bottom of the model box through bolts and is used for controlling the height of the liquid level in the latex film;
the first normally closed electromagnetic valve is positioned at the bottom of the glue storage tank and is used for controlling the start and the end of the discharge of the locking glue in the inner thread of the glue storage tank;
the first flow control valve is positioned on the glue discharge pipe and close to the first normally closed electromagnetic valve and is used for controlling the volume of the thread locking glue discharged into the latex film;
the second normally closed electromagnetic valve is positioned at the intersection of the waste liquid collecting pipe and the surface of the model soil and has the function of enabling the liquid level of the sodium chloride solution in the latex film to be flush with the surface of the model soil;
the third normally closed electromagnetic valve is positioned at the intersection of the waste liquid collecting pipe and the model underground continuous wall groove and is used for regulating and controlling the liquid level height of the sodium chloride solution in the latex film so as to simulate the phenomenon that the liquid level of mud in the underground continuous wall groove is reduced in actual construction;
the third flow control valve is positioned at the bottom of the third normally closed electromagnetic valve and is used for controlling the reduction amplitude of the liquid level height of the sodium chloride solution in the latex membrane;
the ball valve is arranged at the bottom opening of the hopper and is used for controlling the volume of the activated sand-stainless steel powder mixture flowing into the latex film;
the glue discharging pipe is a rubber hose, one end of the glue discharging pipe is connected with the first normally closed electromagnetic valve at the bottom of the glue storage box, the other end of the glue discharging pipe is freely arranged in the latex film, and the glue discharging pipe is used for providing a channel for discharging the thread locking glue in the glue storage box into the latex film;
the waste liquid collecting pipe is a PVC hard pipe, one end of the waste liquid collecting pipe is connected with the waste liquid collector, the other end of the waste liquid collecting pipe is connected with the bottom of the latex film and the position where the latex film is flush with the surface of the model soil, and the waste liquid collecting pipe is used for providing a channel for discharging redundant sodium chloride solution or thread locking glue in the latex film into the waste liquid collector;
the exhaust pipe is a PVC hard pipe, the bottom end of the exhaust pipe is connected with the waste liquid collector, and the top end of the exhaust pipe extends to the outside of the model soil, so that the exhaust pipe has the function of exhausting air in the waste liquid collector, and a space is reserved for a sodium chloride solution or a thread locking glue which is exhausted into the waste liquid collector;
the thread locking glue is stored in a glue storage box and used for simulating a cementing material of cast-in-place concrete of the underground continuous wall; the density of the thread locking glue is greater than that of the sodium chloride solution;
the activated sand-stainless steel powder mixture is filled in the hopper, consists of a proper amount of coarse sand, stainless steel powder and a surfactant (the specific components can be selected and adjusted automatically according to the gravity), and is used for simulating the coarse aggregate of the cast-in-place concrete of the underground continuous wall; the surface active agent has the functions of preventing the segregation phenomenon of the activated sand-stainless steel powder mixture in a supergravity state and accelerating the hardening reaction; the volume weight of the activated sand-stainless steel powder mixture is equivalent to that of reinforced concrete in actual engineering;
the sodium chloride solution is filled in the latex film before the centrifuge rotates, and the initial liquid level of the sodium chloride solution is higher than the surface of the model soil; the effect of the sodium chloride solution includes two aspects, one is to simulate the underground connectionThe method is characterized in that the method comprises the following steps of (1) acting on initial ground stress on the inner wall of a groove before wall-following construction, and (2) acting on an unloading effect of soil pressure around the inner wall of the groove in the process of excavating the slurry retaining wall of the underground continuous wall; for action 1, the amount h of the sodium chloride solution above the surface of the model soil should satisfy one of the following equations as much as possible: h ═ y (γ)soil-γNaCl)H/γNaCl、K0z＝(hγNaCl-z(γNaCl-γw))/(z(γsoil-γw) In the formula of gamma)soil、γNaCl、γwRespectively the gravities of model soil, sodium chloride solution and underground water, z is the depth below the surface of the model soil, H is the depth of a trench of the model underground diaphragm wall, K0zIs the coefficient of static soil pressure at the z position; for the action 2, the height of the liquid level of the sodium chloride solution is reduced to be flush with the surface of the model soil by regulating and controlling a second normally closed electromagnetic valve and a third normally closed electromagnetic valve;
the tank bottom micro pore pressure meter is arranged at the bottom of the latex film and used for monitoring the liquid level height of the sodium chloride solution in the latex film so as to feed back and adjust the volume of the second normally closed electromagnetic valve, the third normally closed electromagnetic valve or the sodium chloride solution injected into the latex film;
the environment effect measuring system comprises a differential displacement meter, a laser displacement meter, a micro soil pressure sensor, a micro pore water pressure sensor, a strain gauge, a hollow sleeve and a plastic sheet;
the differential displacement meter is fixed at a preset position on the auxiliary top plate of the model box and is used for measuring the surface subsidence or uplift condition in the underground continuous wall construction process; the differential displacement meter is arranged more closely near the model underground continuous wall groove and is arranged more sparsely far away from the model underground continuous wall groove;
the laser displacement meter is fixed at a position, corresponding to the axis of the model tunnel, on the model box auxiliary top plate and used for measuring vault settlement of the model tunnel;
the miniature soil pressure sensor is embedded in the model soil and used for quantitatively measuring the influence effect of the underground continuous wall construction on the stratum soil pressure;
the micro pore water pressure sensors are embedded near the micro soil pressure sensors in the model soil, the number of the micro pore water pressure sensors is equal to that of the micro soil pressure sensors, and the elevations of the micro pore water pressure sensors correspond to the elevations of the micro soil pressure sensors one by one; the micro pore water pressure sensor is used for quantitatively measuring the influence effect of the underground continuous wall construction on the formation pore water pressure;
the strain gauge is adhered to the inner surface and the outer surface of the model tunnel and used for measuring the bending moment change condition of the model tunnel in the underground continuous wall construction process; the conversion formula between the reading of the strain gauge and the bending moment is
Wherein M is a bending moment, E is an elastic modulus of the model tunnel, epsiloni、εeRespectively the readings of the strain gauges on the inner surface and the outer surface of the model tunnel, b is unit length and htunnelThe thickness of the model tunnel;
the hollow sleeve is vertically buried in the model soil, one end of the hollow sleeve is connected with the outer surface of the arch crown of the model tunnel through a high-strength adhesive, and the other end of the hollow sleeve extends out of the surface of the model soil for a certain distance; the hollow sleeve has the function of cooperatively deforming with the arch crown of the model tunnel, so that convenience is provided for measuring the deformation of the arch crown of the model tunnel;
the plastic sheet is a rectangular sheet (the thickness is not more than 2cm), has a smooth surface, is connected with the top end of the hollow sleeve through a high-strength adhesive and is used for reflecting signals of the laser displacement meter;
the invention also provides a centrifugal model test method for researching the construction environment effect of the underground diaphragm wall, which is realized based on the device and comprises the following steps:
(1) preparing materials and devices required by the test, and calibrating various components included in the environmental effect measuring system;
(2) marking the positions of various models and components needing to be subsequently installed on the inner wall of the model box by using a mark pen;
(3) installing a waste liquid collector at a corresponding position at the bottom of a model box, installing an exhaust pipe and a waste liquid collecting pipe on the waste liquid collector, and installing a second normally closed electromagnetic valve, a third normally closed electromagnetic valve and a third flow control valve at preset positions on the waste liquid collecting pipe;
(4) pouring model soil into the model box by adopting a sand rain method until the elevation of the bottom surface of the trench of the model underground continuous wall is reached according to the drop height required for reaching the preset dry density, and timely installing a micro soil pressure sensor and a micro pore water pressure sensor which are positioned below the trench of the model underground continuous wall at the preset position in the model soil in the process;
(5) sleeving a latex film on a temporary template, mounting a groove bottom micro pore pressure meter on the inner surface of the latex film near a liquid discharge hole at the bottom of the temporary template, and fixing the temporary template sleeved with the latex film at a preset position of an auxiliary top plate of a model box by adopting a connector and a fixed rod;
(6) continuously adopting a sand rain method to pour model soil until the arch bottom elevation of the model tunnel is reached, in the process, installing corresponding micro soil pressure sensors and micro pore water pressure sensors at preset positions timely, and then installing the model tunnel which is attached with the strain gauge and is connected with the hollow sleeve and the plastic sheet at the preset positions;
(7) continuously adopting a sand rain method to pour the model soil until the elevation of the bottom surface of the model guide wall is reached, timely installing corresponding micro soil pressure sensors and micro pore water pressure sensors at preset positions in the process, then installing the model guide wall at the preset positions, continuously adopting the sand rain method to pour the model soil until the elevation of the surface of the model soil is reached, and utilizing water to saturate the model soil;
(8) fixing the differential displacement meter and the hopper on an auxiliary top plate of the model box, injecting a sodium chloride solution with a preset weight into the latex film through the hopper while pulling out the edge of the temporary template until the liquid level of the sodium chloride solution reaches a preset height, and then closing a ball valve at an opening at the bottom of the hopper;
(9) fixing a glue storage tank filled with thread locking glue at a preset position of an auxiliary top plate of a model box by using a fixing block, mounting a first normally closed electromagnetic valve at the bottom of the glue storage tank, connecting a glue discharge pipe, mounting a first flow control valve on the glue discharge pipe, and placing the other end of the glue discharge pipe at the bottom of a latex film;
(10) filling the prepared activated sand-stainless steel powder mixture into a hopper, hanging a model box into a centrifuge basket, closing an armored door of a centrifuge chamber, debugging an environmental effect measuring system, starting the centrifuge, and turning the centrifuge to a preset hypergravity level;
(11) opening a second normally closed electromagnetic valve, keeping the other electromagnetic valves in a closed state, discharging the sodium chloride solution in the latex membrane into a waste liquid collector until the liquid level of the sodium chloride solution is lowered to be flush with the surface of the model soil, and in the state, turning the machine for a certain time to read the reading of the environmental effect measurement system so as to simulate the slurry retaining wall excavation process of the underground continuous wall;
(12) if the influence effect of slurry liquid level reduction in the groove on the surrounding environment in the underground continuous wall construction process needs to be researched, the operation in the step can be executed, namely, a third normally closed electromagnetic valve is opened, the sodium chloride solution in the latex film is continuously discharged into a waste liquid collector, so that the liquid level of the sodium chloride solution is reduced to be below the surface of the model soil, and the amplitude of the liquid level reduction is regulated and controlled through a third flow control valve;
(13) opening a first normally closed electromagnetic valve and a second normally closed electromagnetic valve, discharging the thread locking glue in the glue storage tank into a latex film at a certain flow rate, gradually extruding and lifting the liquid surface of the sodium chloride solution in the latex film due to the fact that the weight of the sodium chloride solution is lower than that of the thread locking glue, then discharging the sodium chloride solution into a waste liquid collector through a waste liquid collecting pipe, continuing the process until the liquid surface of the thread locking glue in the latex film is flush with the surface of the model soil, and closing the first normally closed electromagnetic valve;
(14) opening a ball valve, filling an activated sand-stainless steel powder mixture with a preset volume in a hopper into a latex film, discharging redundant thread locking glue in the latex film into a waste liquid collector through a second normally closed electromagnetic valve and a waste liquid collecting pipe, continuously rotating the machine for a certain time, and collecting the reading of an environmental effect measuring system after the reading of the environmental effect measuring system is stable;
(15) and stopping the machine, hanging out the model box, disassembling and cleaning the model box, and finishing the test.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method adopts the specific severe sodium chloride solution (the severe degree of which is lower than that of the thread locking glue) to simulate the slurry adopted in the grooving construction process of the underground diaphragm wall, has the advantages of easily available materials, low price, environmental protection, convenient severe control, safety, harmlessness and the like, and effectively avoids the problem of strong corrosivity when the zinc chloride solution is used;
(2) the initial ground stress acting on the groove position of the underground continuous wall before the underground continuous wall is excavated can be conveniently and accurately reproduced by regulating the height of the liquid level of the sodium chloride solution exceeding the surface of the model soil;
(3) the invention can better simulate the soil pressure unloading effect in the grooving construction process of the underground diaphragm wall by reducing the liquid level of the sodium chloride solution to the position flush with the soil surface of the model;
(4) the bottom of the latex film is provided with a groove bottom micro pore pressure meter, a third normally closed electromagnetic valve, a third flow control valve and a waste liquid collecting pipe, so that the amplitude of the sodium chloride solution lower than the surface of the model soil can be controlled quantitatively, and an effective simulation means is provided for researching the influence effect of slurry loss in the groove of the underground continuous wall on the stability of the groove wall and surrounding strata and structures;
(5) the method adopts the mixture of the coarse sand, the stainless steel powder, the surface active agent and the thread locking glue to simulate the cast-in-place reinforced concrete of the underground continuous wall, and the material weight of the mixture is approximately equal to that of the reinforced concrete material used in the actual engineering, so that the method is more in line with the actual situation; in addition, the mixture material is not easy to separate under a high-hypergravity environment, the initial setting time is less than 2 minutes, the final setting time is within 15 minutes, and better similarity between a model and a prototype is powerfully ensured.
Drawings
FIG. 1 is a front view of a mold apparatus;
FIG. 2 is a top view of the mold apparatus;
FIG. 3 is a schematic diagram of arrangement of strain gauges in the axial direction of a model tunnel;
FIG. 4 is a schematic diagram of a full bridge circuit of the strain gauge;
FIG. 5 is a process of preparing cast-in-place reinforced concrete models;
in the figure: the device comprises a model box 1, model soil 2, a model tunnel 3, an underground continuous wall construction simulation system 4, an environmental effect measurement system 5, a box body 1-1, an auxiliary top plate 1-2, a model underground continuous wall groove 4-1, a model guide wall 4-2, a latex film 4-3, a temporary template 4-4, a hopper 4-5, a connector 4-6, a fixing rod 4-7, a fixing block 4-8, a glue storage tank 4-9, a waste liquid collector 4-10, a first normally closed electromagnetic valve 4-11, a first flow control valve 4-12, a second normally closed electromagnetic valve 4-13, a third normally closed electromagnetic valve 4-14, a third flow control valve 4-15, a ball valve 4-16, a glue discharge pipe 4-17, a waste liquid collection pipe 4-18, an exhaust pipe 4-19, a glue discharge pipe 4-17, a glue discharge pipe 4, 4-20 parts of thread locking glue, 4-21 parts of activated sand-stainless steel powder mixture, 4-22 parts of sodium chloride solution, 4-23 parts of groove bottom micro pore pressure gauge, 5-1 parts of differential displacement gauge, 5-2 parts of laser displacement gauge, 5-3 parts of micro soil pressure sensor, 5-4 parts of micro pore water pressure sensor, 5-5 parts of strain gauge, 5-6 parts of hollow sleeve and 5-7 parts of plastic sheet.
Detailed Description
The invention will be further described with reference to the following drawings and specific embodiments.
As shown in fig. 1-5, the present invention provides a schematic diagram of a centrifugal model testing apparatus and method for studying the environmental effect of underground continuous wall construction, the apparatus includes a model box 1, model soil 2, a model tunnel 3, an underground continuous wall construction simulation system 4, and an environmental effect measurement system 5;
the model box 1 consists of a box body 1-1 and an auxiliary top plate 1-2; the model soil 2 is filled in the model box 1, and the filling height is lower than the height of the box body; the model tunnel 3 is embedded in the model soil 2 and is formed by processing an organic glass tube at one time; the axial direction of the model tunnel 3 is parallel to the extending direction of the model underground continuous wall groove 4-1; the underground continuous wall construction simulation system 4 comprises a model underground continuous wall groove 4-1, a model guide wall 4-2, a latex film 4-3, a temporary template 4-4, a hopper 4-5, a connector 4-6, a fixing rod 4-7, a fixing block 4-8, a glue storage tank 4-9, a waste liquid collector 4-10, a first normally closed electromagnetic valve 4-11, a first flow control valve 4-12, a second normally closed electromagnetic valve 4-13, a third normally closed electromagnetic valve 4-14, a third flow control valve 4-15, a ball valve 4-16, a glue discharge pipe 4-17, a waste liquid collection pipe 4-18, an exhaust pipe 4-19, a thread locking glue 4-20, an activated sand-stainless steel powder mixture 4-21, a sodium chloride solution 4-22, a rust-removing agent, 4-23 of a groove bottom micro pore pressure meter;
embedding the model underground continuous wall groove 4-1 into the model soil 2; the model guide wall 4-2 is tightly attached to the side face of the model underground continuous wall groove 4-1 within the range from the top to the lower 20 mm; the latex film 4-3 is tightly attached to the inner wall of the groove 4-1 of the model underground continuous wall; the top of the temporary template 4-4 is connected with a connector 4-6; the hopper 4-5 is fixed on the auxiliary top plate 1-2 of the model box through a fixing block 4-8 at a position corresponding to the groove 4-1 of the model underground continuous wall, and the bottom of the hopper 4-5 is connected with the latex film 4-3 through a connector 4-6; the fixed blocks 4-8 are positioned at two ends of the glue storage tank 4-9 and the hopper 4-5; the glue storage tank 4-9 is fixed on the auxiliary top plate 1-2 of the model box through bolts; the waste liquid collector 4-10 is fixed at the bottom of the model box 1 through bolts; the first normally closed electromagnetic valve 4-11 is positioned at the bottom of the glue storage tank 4-9; the first flow control valve 4-12 is positioned on the glue discharge pipe 4-17 and close to the first normally closed electromagnetic valve 4-11; the second normally closed electromagnetic valve 4-13 is positioned at the intersection part of the waste liquid collecting pipe 4-18 and the surface of the model soil 2; the third normally closed electromagnetic valve 4-14 is positioned at the intersection of the waste liquid collecting pipe 4-18 and the model underground continuous wall groove 4-1; the third flow control valve 4-15 is positioned at the bottom of the third normally closed electromagnetic valve 4-14; the ball valve 4-16 is arranged at the bottom opening of the hopper 4-5; one end of the glue discharge pipe 4-17 is connected with a first normally closed electromagnetic valve 4-11 at the bottom of the glue storage tank 4-9, and the other end is freely arranged in the latex film 4-3; one end of the waste liquid collecting pipe 4-18 is connected with the waste liquid collector 4-10, and the other end is connected with the bottom of the latex film 4-3 and the position where the latex film 4-3 is flush with the surface of the model soil 2; the bottom end of the exhaust pipe 4-19 is connected with the waste liquid collector 4-10, and the top end extends to the outside of the model soil 2; the thread locking glue 4-20 is stored in the glue storage tank 4-9; activated sand-stainless steel powder mixture 4-21 is filled in hopper 4-5; sodium chloride solution 4-22 is filled in the latex film 4-3 before the centrifuge rotates, and the initial liquid level is higher than the surface of the model soil 2; the groove bottom micro pore pressure meter 4-23 is arranged at the bottom of the latex film 4-3 and is used for monitoring the liquid level height of the sodium chloride solution 4-22 in the latex film 4-3;
the environmental effect measuring system 5 comprises a differential type displacement meter 5-1, a laser displacement meter 5-2, a micro soil pressure sensor 5-3, a micro pore water pressure sensor 5-4, a strain gauge 5-5, a hollow sleeve 5-6 and a plastic sheet 5-7; the differential displacement meter 5-1 is fixed at a preset position on the auxiliary top plate 1-2 of the model box; the laser displacement meter 5-2 is fixed on the model box auxiliary top plate 1-2 at a position corresponding to the axis of the model tunnel 3; the miniature soil pressure sensor 5-3 is embedded in the model soil 2; the micro pore water pressure sensor 5-4 is embedded in the model soil 2 near the micro soil pressure sensor 5-3; the strain gauges 5-5 are adhered to the inner surface and the outer surface of the model tunnel 3; the hollow casing pipes 5-6 are vertically buried in the model soil 2, one end of the hollow casing pipe is connected with the outer surface of the arch crown of the model tunnel 3 through a high-strength adhesive, and the other end of the hollow casing pipe extends out of the surface of the model soil 2 for a certain distance; the plastic sheet 5-7 is attached to the top end of the hollow cannula 5-6 by a high strength adhesive.
The invention provides a centrifugal model test method for researching the environmental effect of an underground diaphragm wall, which comprises the following steps:
step 1, preparing materials, devices and calibrating components;
marking the positions of various models and components on the inner wall of the model box 1;
step 4, pouring model soil 2 into the model box 1 by adopting a sand rain method until the elevation of the bottom surface of the trench 4-1 of the model underground continuous wall, and timely installing a micro soil pressure sensor 5-3 and a micro pore water pressure sensor 5-4 in the process;
step 5, sleeving a latex film 4-3 on a temporary template 4-4, mounting a groove bottom micro pore pressure meter 4-23 on the inner surface of the latex film 4-3 near a liquid discharge hole at the bottom of the temporary template 4-4, and fixing the temporary template 4-4 sleeved with the latex film 4-3 at a preset position of an auxiliary top plate 1-2 of the model box by adopting a connector 4-6 and a fixing rod 4-7;
step 6, continuously adopting a sand rain method to pour model soil 2 until the arch bottom elevation of the model tunnel 3, in the process, installing a miniature soil pressure sensor 5-3 and a miniature pore water pressure sensor 5-4 in due time, and then installing the model tunnel 3 which is attached with a strain gauge 5-5 and is connected with a hollow sleeve 5-6 and a plastic sheet 5-7 at a preset position;
step 7, continuing to pour the model soil 2 until the elevation of the bottom surface of the model guide wall 4-2 is reached, timely installing a micro soil pressure sensor 5-3 and a micro pore water pressure sensor 5-4 in the process, then installing the model guide wall 4-2 at a preset position, pouring the model soil 2 until the surface elevation of the model soil 2, and saturating the model soil 2 with water (a water bucket filled with water can be used for injecting water into the model soil through a water pipe to saturate the model soil);
step 8, fixing a differential displacement meter 5-1 and a hopper 4-5 on an auxiliary top plate 1-2 of a model box 1, pouring a sodium chloride solution 4-22 with a preset weight into a latex film 4-3 through the hopper 4-5 while pulling out the temporary template 4-4 until the liquid level of the sodium chloride solution 4-22 reaches a preset height, and then closing a ball valve 4-16 at an opening at the bottom of the hopper 4-5;
step 9, fixing a glue storage tank 4-9 filled with thread locking glue 4-20 at a preset position of an auxiliary top plate 1-2 of the model box by using a fixing block 4-8, installing a first normally closed electromagnetic valve 4-11 at the bottom of the glue storage tank 4-9, connecting a glue discharge pipe 4-17, installing a first flow control valve 4-12 on the glue discharge pipe 4-17, and placing the other end of the glue discharge pipe 4-17 at the bottom of the latex film 4-3;
step 10, filling a prepared activated sand-stainless steel powder mixture 4-21 into a hopper 4-5, hanging a model box 1 into a basket of a centrifuge, closing an armored door of a centrifuge chamber, debugging an environmental effect measuring system 5, starting the centrifuge, and turning the centrifuge to a preset hypergravity level;
step 11, opening a second normally closed electromagnetic valve 4-13, keeping the other electromagnetic valves in a closed state, discharging the sodium chloride solution 4-22 in the latex film 4-3 into a waste liquid collector 4-10 until the liquid level of the sodium chloride solution 4-22 is lowered to be flush with the surface of the model soil 2, and in the state, turning the machine for a period of time to read the reading of the environmental effect measuring system 5 so as to simulate the slurry retaining wall excavation process of the underground continuous wall;
step 12, if the influence effect of slurry liquid level reduction in the groove on the surrounding environment in the underground continuous wall construction process needs to be researched, the operation in the step can be executed, namely, a third normally closed electromagnetic valve 4-14 is opened, sodium chloride solution 4-22 in a latex film 4-3 is continuously discharged into a waste liquid collector 4-10, so that the liquid level of the sodium chloride solution 4-22 is reduced to be below the surface of the model soil 2, and the amplitude of the liquid level reduction is regulated and controlled through a third flow control valve 4-15;
step 13, opening a first normally closed electromagnetic valve 4-11 and a second normally closed electromagnetic valve 4-13, discharging the thread locking glue 4-20 in the glue storage tank 4-9 into the latex film 4-3 according to a certain flow rate (10-30 ml/s), gradually extruding and lifting the liquid level of the sodium chloride solution 4-22 in the latex film 4-3 due to the fact that the weight of the sodium chloride solution is lower than that of the thread locking glue 4-20, then discharging the sodium chloride solution into a waste liquid collector 4-10 through a waste liquid collecting pipe 4-18, continuing the process until the liquid level of the thread locking glue 4-20 in the latex film 4-3 is flush with the surface of the model soil 2, and closing the first normally closed electromagnetic valve 4-11;
14, opening a ball valve 4-16, filling activated sand-stainless steel powder mixture 4-21 with a preset volume in a hopper 4-5 into a latex film 4-3, discharging redundant thread locking glue 4-20 in the latex film 4-3 into a waste liquid collector 4-18 through a second normally closed electromagnetic valve 4-13 and a waste liquid collecting pipe 4-18, continuing to rotate for a certain time, and collecting the reading of the environmental effect measuring system 5 after the reading of the environmental effect measuring system 5 is stable;
and step 15, stopping the machine, hanging out the model box 1, disassembling and cleaning the model box, and finishing the test.
Claims (10)
1. A centrifugal model test device for researching the construction environmental effect of an underground continuous wall is characterized by comprising a model box, model soil, a model tunnel, an underground continuous wall construction simulation system and an environmental effect measurement system;
the model box comprises a box body and an auxiliary top plate; the bottom of the box body is provided with uniformly distributed drain holes and drain pipes communicated with the inside and the outside, model soil is filled in the model box, and water is injected into the model soil through the drain pipes to saturate the model soil; the auxiliary top plate is arranged at the top of the box body and used for providing support for an underground continuous wall construction simulation system and an environmental effect measurement system;
the underground continuous wall construction simulation system comprises a model underground continuous wall groove, a model guide wall, a latex film, a temporary template, a hopper, a connector, a fixing rod, a glue storage tank, a waste liquid collector, a glue discharge pipe, a waste liquid collection pipe, an exhaust pipe and a tank bottom micro pore pressure meter; the model underground continuous wall groove is embedded into model soil, the bottom surface of the model underground continuous wall groove is parallel to a horizontal plane, and the side surface of the model underground continuous wall groove is vertical to the horizontal plane; the model guide wall is tightly attached to the side surface of the model underground continuous wall groove within the range from the top to the lower 20 mm; the latex film is tightly attached to the inner wall of the groove of the model underground continuous wall, the plane size of the latex film is the same as that of the groove of the model underground continuous wall, the height of the latex film is larger than the depth of the groove of the model underground continuous wall, and sodium chloride solution is initially filled in the latex film; the temporary template is used for supporting the latex film in the model soil filling process and reserving a geometric space of the model underground continuous wall groove, the bottom of the temporary template is provided with a liquid discharge hole, and the top of the temporary template is connected with the connector; the hopper is fixedly arranged on the auxiliary top plate at a position corresponding to the groove of the model underground continuous wall, the bottom of the hopper is connected with the latex film through a connector, and the activated sand-stainless steel powder mixture is filled in the hopper and consists of coarse sand, stainless steel powder and a surfactant; the connector is a double-layer steel sheet with a hole, and the steel sheets are connected through a bolt; the fixing rod is a threaded steel rod and is used for fixing the connector at a preset position on the auxiliary top plate; the glue storage tank is fixed on the auxiliary top plate and stores thread locking glue for simulating a cast-in-place concrete cementing material, and the gravity of the thread locking glue is greater than that of a sodium chloride solution; the waste liquid collector is fixed at the bottom of the model box and is used for controlling the height of the liquid level in the latex film; the glue discharge pipe is used for discharging the thread locking glue in the glue storage tank into the latex film; the waste liquid collecting pipe is used for discharging redundant sodium chloride solution or thread locking glue in the latex film into the waste liquid collector; the exhaust pipe is used for exhausting air in the waste liquid collector, so that a space is reserved for the sodium chloride solution or the thread locking glue which is exhausted into the waste liquid collector; the tank bottom micro pore pressure meter is arranged at the bottom of the latex film and is used for monitoring the liquid level height of the sodium chloride solution in the latex film;
the model tunnel is buried in model soil, the axial direction of the model tunnel is parallel to the extending direction of the groove of the model underground connecting wall, and the clear distance between the model tunnel and the inner wall of the box body parallel to the axial direction of the model tunnel is more than the times of the outer diameter of the model tunnel;
the environmental effect measuring system is used for measuring the surface subsidence or uplift condition in the underground continuous wall construction process, the vault subsidence and bending moment change condition of the model tunnel and the influence of the underground continuous wall construction on the stratum soil pressure and the pore water pressure.
2. The centrifugal model test device for studying the environmental effect of underground diaphragm wall construction according to claim 1, wherein the glue storage tank and the hopper are fixed on the auxiliary top plate through fixing blocks for preventing the glue storage tank and the hopper from shaking left and right during the rotation of the centrifuge.
3. The centrifugal model test device for researching the environmental effect of the underground continuous wall construction according to claim 1, wherein the underground continuous wall construction simulation system further comprises a first normally closed type electromagnetic valve, a first flow control valve, a second normally closed type electromagnetic valve, a third flow control valve and a ball valve;
the first normally closed electromagnetic valve is positioned at the bottom of the glue storage tank and used for controlling the start and the end of the discharge of the locking glue in the inner thread of the glue storage tank; the first flow control valve is positioned on the glue discharge pipe and close to the first normally closed electromagnetic valve and is used for controlling the volume of the thread locking glue discharged into the latex film;
the second normally closed electromagnetic valve is positioned at the intersection of the waste liquid collecting pipe and the surface of the model soil and is used for enabling the liquid level of the sodium chloride solution in the latex film to be flush with the surface of the model soil;
the third normally closed electromagnetic valve is positioned at the intersection of the waste liquid collecting pipe and the model underground continuous wall groove and is used for regulating and controlling the liquid level height of the sodium chloride solution in the latex film so as to simulate the phenomenon that the liquid level of mud in the underground continuous wall groove is reduced in actual construction; the third flow control valve is positioned at the bottom of the third normally closed electromagnetic valve and is used for controlling the reduction amplitude of the liquid level height of the sodium chloride solution in the latex membrane;
the ball valve is arranged at the bottom opening of the hopper and is used for controlling the volume of the activated sand-stainless steel powder mixture flowing into the latex film.
4. The centrifugal model test device for studying the construction environment effect of the underground continuous wall as claimed in claim 3, wherein the sodium chloride solution is filled in the latex film before the centrifuge rotates, and the initial liquid level is higher than the surface of the model soil; the effect of the sodium chloride solution comprises two aspects, namely the sodium chloride solution is used for simulating the initial ground stress acting on the inner wall of the groove before the underground continuous wall is constructed, and the amount h of the sodium chloride solution higher than the surface of the model soil at the moment is one of the following formulas: h ═ y (γ)soil-γNaCl)H/γNaCl、K0z＝(hγNaCl-z(γNaCl-γw))/(z(γsoil-γw) In the formula of gamma)soil、γNaCl、γwRespectively the gravities of model soil, sodium chloride solution and underground water, z is the depth below the surface of the model soil, H is the depth of a trench of the model underground diaphragm wall, K0zIs the coefficient of static soil pressure at the z position; and the second mode is used for simulating the unloading effect of the soil pressure around the inner wall of the trench in the process of excavating the slurry retaining wall of the underground diaphragm wall, and the liquid level of the sodium chloride solution is reduced to be flush with the surface of the model soil by regulating and controlling the second normally closed electromagnetic valve and the third normally closed electromagnetic valve.
5. The centrifugal model test device for researching the environmental effect of underground continuous wall construction according to claim 1, wherein the glue discharge pipe is a rubber hose, and the waste liquid collecting pipe and the exhaust pipe are PVC hard pipes.
6. The centrifugal model test device for researching the construction environment effect of the underground continuous wall as claimed in claim 1, wherein the box body is formed by welding high-strength aluminum alloy plates, stiffening plates are mounted on the outer surfaces of the high-strength aluminum alloy plates, and the tensile strength of the high-strength aluminum alloy plates is greater than 500 MPa.
7. The centrifugal model test device for researching the construction environment effect of the underground continuous wall as claimed in claim 1, wherein the model soil is saturated sandy soil, and the average particle size of the model soil is 80-160 μm.
8. The centrifugal model test device for researching the construction environment effect of the underground continuous wall as claimed in claim 1, wherein the model tunnel is formed by machining a plastic glass tube at one time.
9. The centrifugal model test device for studying the environmental effect of underground continuous wall construction according to claim 1, wherein the environmental effect measuring system comprises a differential displacement gauge, a laser displacement gauge, a micro soil pressure sensor, a micro pore water pressure sensor, a strain gauge, a hollow sleeve and a plastic sheet;
the differential displacement meter is fixed at a preset position on the auxiliary top plate and used for measuring the surface subsidence or uplift condition in the construction process of the underground continuous wall;
the laser displacement meter is fixed on the auxiliary top plate at a position corresponding to the axis of the model tunnel and is used for measuring vault settlement of the model tunnel;
the miniature soil pressure sensor is embedded in the model soil and used for quantitatively measuring the influence effect of the construction of the underground diaphragm wall on the stratum soil pressure;
the micro pore water pressure sensor is embedded near the micro soil pressure sensor in the model soil and is used for quantitatively measuring the influence effect of the underground continuous wall construction on the formation pore water pressure; the number of the micro pore water pressure sensors is equal to that of the micro soil pressure sensors, and the elevations of the micro pore water pressure sensors correspond to the elevations of the micro soil pressure sensors one by one;
the strain gauge is adhered to the inner surface and the outer surface of the model tunnel and used for measuring the bending moment change condition of the model tunnel in the construction process of the underground continuous wall; the conversion formula between the reading of the strain gauge and the bending moment is
Wherein M is a bending moment, E is an elastic modulus of the model tunnel, epsiloni、εeRespectively the readings of the strain gauges on the inner surface and the outer surface of the model tunnel, b is unit length and htunnelThe thickness of the model tunnel;
the hollow casing is vertically buried in the model soil, one end of the hollow casing is connected with the outer surface of the vault of the model tunnel, and the other end of the hollow casing extends out of the surface of the model soil for a certain distance; the hollow sleeve is used for being deformed in coordination with the vault of the model tunnel, so that convenience is brought to measurement of deformation of the vault of the model tunnel;
the plastic sheet is connected with the top end of the hollow sleeve and used for reflecting signals of the laser displacement meter; the plastic sheet is a rectangular sheet with a smooth surface, and the thickness of the rectangular sheet is not more than 2 cm.
10. A centrifugal model test method for studying the environmental effect of underground diaphragm wall construction, which is implemented based on the device of any one of claims 1 to 9 and comprises the following steps:
(1) preparing materials and devices required by the test, and calibrating various components included in the environmental effect measuring system;
(2) marking the positions of various models and components needing to be subsequently installed on the inner wall of the model box by using a mark pen;
(3) installing a waste liquid collector at a corresponding position at the bottom of a model box, installing an exhaust pipe and a waste liquid collecting pipe on the waste liquid collector, and installing a second normally closed electromagnetic valve, a third normally closed electromagnetic valve and a third flow control valve at preset positions on the waste liquid collecting pipe;
(4) pouring model soil into the model box by adopting a sand rain method until the elevation of the bottom surface of the trench of the model underground continuous wall is reached according to the drop height required for reaching the preset dry density, and timely installing a micro soil pressure sensor and a micro pore water pressure sensor which are positioned below the trench of the model underground continuous wall at the preset position in the model soil in the process;
(5) sleeving a latex film on a temporary template, mounting a groove bottom micro pore pressure meter on the inner surface of the latex film near a liquid discharge hole at the bottom of the temporary template, and fixing the temporary template sleeved with the latex film at a preset position of an auxiliary top plate of a model box by adopting a connector and a fixed rod;
(6) continuously adopting a sand rain method to pour model soil until the arch bottom elevation of the model tunnel is reached, in the process, installing corresponding micro soil pressure sensors and micro pore water pressure sensors at preset positions timely, and then installing the model tunnel which is adhered with the strain gauge and is connected with the hollow sleeve and the plastic sheet at the preset positions;
(7) continuously adopting a sand rain method to pour the model soil until the elevation of the bottom surface of the model guide wall is reached, timely installing corresponding micro soil pressure sensors and micro pore water pressure sensors at preset positions in the process, then installing the model guide wall at the preset positions, continuously adopting the sand rain method to pour the model soil until the elevation of the surface of the model soil is reached, and utilizing water to saturate the model soil;
(8) fixing the differential displacement meter and the hopper on an auxiliary top plate of the model box, injecting a sodium chloride solution with a preset weight into the latex film through the hopper while pulling out the edge of the temporary template until the liquid level of the sodium chloride solution reaches a preset height, and then closing a ball valve at an opening at the bottom of the hopper;
(9) fixing a glue storage tank filled with thread locking glue at a preset position of an auxiliary top plate of a model box by using a fixing block, mounting a first normally closed solenoid valve at the bottom of the glue storage tank and connecting the first normally closed solenoid valve with a glue discharge pipe, mounting a first flow control valve on the glue discharge pipe, and placing the other end of the glue discharge pipe at the bottom of a latex film;
(10) filling the prepared activated sand-stainless steel powder mixture into a hopper, hanging a model box into a centrifuge basket, closing an armored door of a centrifuge chamber, debugging an environmental effect measuring system, and starting the centrifuge to enable the model box to reach a preset hypergravity level;
(11) opening a second normally closed electromagnetic valve, keeping the other electromagnetic valves in a closed state, discharging the sodium chloride solution in the latex membrane into a waste liquid collector until the liquid level of the sodium chloride solution is lowered to be flush with the surface of the model soil, and in the state, rotating a centrifuge for a period of time and reading the reading of an environmental effect measuring system so as to simulate the slurry retaining wall excavation process of the underground continuous wall;
(12) if the influence effect of slurry liquid level reduction in the groove on the surrounding environment in the underground continuous wall construction process needs to be researched, a third normally closed electromagnetic valve is opened, sodium chloride solution in the latex film is continuously discharged into a waste liquid collector, so that the liquid level of the sodium chloride solution is reduced to be below the surface of the model soil, and the amplitude of the liquid level reduction is regulated and controlled through a third flow control valve;
(13) opening a first normally closed electromagnetic valve and a second normally closed electromagnetic valve, discharging the thread locking glue in the glue storage tank into a latex film at a flow rate of 10-30 ml/s, gradually extruding and lifting the liquid surface of a sodium chloride solution in the latex film due to the fact that the sodium chloride solution is lower than the thread locking glue, then discharging the liquid surface into a waste liquid collector through a waste liquid collecting pipe, and closing the first normally closed electromagnetic valve until the liquid surface of the thread locking glue in the latex film is flush with the surface of the model soil in the process;
(14) opening a ball valve, filling an activated sand-stainless steel powder mixture with a preset volume in a hopper into a latex film, discharging redundant thread locking glue in the latex film into a waste liquid collector through a second normally closed electromagnetic valve and a waste liquid collecting pipe, continuously rotating a centrifugal machine, and collecting the reading of an environmental effect measuring system after the reading of the environmental effect measuring system is stable;
(15) and stopping the machine, hanging out the model box, disassembling and cleaning the model box, and finishing the test.
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