CN113358851B - Model test device and method for simulating tunnel deformation caused by underground water level fluctuation - Google Patents
Model test device and method for simulating tunnel deformation caused by underground water level fluctuation Download PDFInfo
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Abstract
The invention provides a model test device and a test method for simulating tunnel deformation caused by underground water level fluctuation. The model test device comprises a model box, a tunnel model, a tunnel fixing device, a monitoring system and a water injection pumping system. The model test device can truly simulate the tunnel deformation process caused by the underground water level fluctuation, and can accurately measure the changes of the tunnel and surrounding soil displacement field and stress field when the underground water level fluctuates. The test has low cost and wide application prospect.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a model test device and a test method for simulating tunnel deformation caused by underground water level fluctuation.
Background
With the development of urban process and the appearance of oversized cities with large economic scale and strong aggregation in China, the demands on urban space and traffic carrying capacity are continuously increased, and the development and utilization of urban underground space and subway construction are rapidly developed. But in recent years, flood disasters such as mountain floods, waterlogging, river floods and the like frequently occur in China, and the normal use of underground structures is greatly influenced. Therefore, the research of the water level fluctuation has very important practical significance on the action mechanism of the underground structure.
At present, simplified still water buoyancy is often adopted as the design buoyancy of the underground structure in engineering design, and the buoyancy of the underground structure in actual engineering is more complex. In actual engineering, the buoyancy of the underground structure is closely related to the soil permeability coefficient, the groundwater seepage field, the complex building environment around the underground structure and other influencing factors. Therefore, the buoyancy design is optimized by considering the influence of water level fluctuation on the buoyancy of the underground structure and researching the action mechanism of the underground structure.
In the existing research, most scholars only perform buoyancy model test on a simple underground structure, and the change rule of the soil displacement field around the underground structure along with the floating of the underground water level is not considered.
Therefore, it is necessary to develop a test device and a use method capable of monitoring the tunnel buoyancy and the surrounding soil displacement field along with the water level.
Disclosure of Invention
The invention aims to provide a model test device and a test method for simulating tunnel deformation caused by underground water level fluctuation, so as to solve the problems in the prior art.
The technical scheme adopted for achieving the purpose of the invention is that the model test device for simulating tunnel deformation caused by underground water level fluctuation comprises a model box, a tunnel model, a tunnel fixing device, a monitoring system and a water injection pumping system.
The model box comprises a model box main body, a sand cushion layer and a permeable curtain. The model box main body is a rectangular box body with an open upper end. The four side walls of the rectangular box body are a first side plate, a second side plate, a third side plate and a fourth side plate in sequence. The first side plate is a transparent side plate. The sand cushion layer is paved at the bottom of the inner cavity of the model box. The water permeable curtain is of a U-shaped plate structure. The water permeable curtain is vertically arranged in the inner cavity of the model box main body. The opening of the water permeable curtain faces to the first lateral plate. Gaps exist between the three side plates of the permeable curtain and the corresponding side plates of the model box main body. The permeable curtain, the first side plate and the sand cushion layer surround a model soil accommodating space S. Model soil is filled in the model soil accommodating space S. Geotechnical cloth is further arranged between the sandy soil cushion layer and the model soil.
The tunnel model is a hollow cylinder. The tunnel model is buried in model soil. The length direction of the tunnel model is perpendicular to the plate surface of the first side plate. One end of the tunnel model is clung to the first side plate.
The tunnel fixing device comprises a bracket, a U-shaped bracket, a dowel bar and a plurality of fixing bars. The support comprises two upright posts and a cross beam, wherein the heights of the upright posts and the cross beam can be adjusted. The two stand columns are respectively arranged on the upper surfaces of the second side plate and the fourth side plate. The cross beam comprises a cross beam erected between two upright posts and an overhanging longitudinal beam extending from a beam body of the cross beam. The length direction of the cantilever longitudinal beam is parallel to the length direction of the tunnel model. The U-shaped bracket is arranged on the upper surface of the cross beam. The U-shaped bracket has a top wall and two side walls. And a hole for the dowel bar to pass through is formed in the center of the cross beam. And after passing through the corresponding hole, the dowel bar is fixedly connected with the tunnel model at the lower end. The cantilever longitudinal beam is provided with a plurality of holes for the fixing rods to pass through. The fixing rod comprises a rod body and a clamping part. The locking part is arranged on the rod body. The shaft passes through the corresponding hole. The clamping part is placed on the overhanging longitudinal beam. The lower end of the rod body is fixedly connected with the tunnel model.
The monitoring system comprises a pressure monitoring device, a displacement sensor, a model soil displacement monitoring device, a soil pressure sensor, a strain sensor, an industrial camera and a pore water pressure sensor. The pressure monitoring device comprises a foam board and a pressure sensor. The pressure sensor is arranged on the lower surface of the top wall of the U-shaped bracket. The foam board is connected with a pressure sensor. The upper end of the dowel bar is connected with the foam board. The displacement sensor is arranged at the top end of the fixed rod. The model soil displacement monitoring device is embedded in the model soil around the tunnel model and is clung to the first side plate. The soil pressure sensor and the pore water pressure sensor are arranged on the outer wall of the tunnel model. The strain sensor is arranged on the inner wall and the outer wall of the tunnel model. The industrial camera is disposed outside the mold box. The shooting direction of the industrial camera faces the first side plate.
When the model box is in operation, the water injection pumping system injects water or pumps water into the gap between the water permeable curtain and the model box main body. The tunnel model moves with the water level change. The monitoring system acquires the change data and images of the tunnel model and the surrounding soil displacement field and the stress field. And obtaining related rules of tunnel deformation caused by ground water level fluctuation through analyzing the data and the images.
Further, the first side plate is made of organic glass. The tunnel model is made of light plastic.
Further, the water injection pumping system comprises a plurality of water pipes and a water pump. One end of the water pipe is connected with the water pump, and the other end of the water pipe stretches into a gap between the permeable curtain and the model box main body.
Further, silicone grease is uniformly smeared on the outer walls of the tunnel model, the dowel bar and the fixed bar.
The invention also discloses a test method of the model test device for simulating tunnel deformation caused by groundwater level fluctuation, which comprises the following steps:
1) Filling a sand cushion layer at the bottom of the model box main body, and carrying out self-weight consolidation for a set time.
2) And arranging geotextile and a permeable curtain on the sandy soil cushion layer.
3) And filling model soil to a designed height in layers in the model soil accommodating space S. The tunnel model is embedded and fixedly connected with the tunnel fixing device. And continuously filling the model soil to the designed height of the soil layer. And arranging a monitoring system in the filling process.
4) And water is injected into a gap between the permeable curtain and the model box main body to the designed water level by using the water injection pumping system. And (5) carrying out self-weight consolidation on the water-injected model soil for a set time.
5) Data of the pressure sensor and the displacement sensor are recorded as initial data. And shooting the initial position of the model soil displacement monitoring device by using an industrial camera.
6) And water is injected into a gap between the permeable curtain and the model box main body to the designed water level by using the water injection pumping system. And continuously shooting the position change of the model soil displacement monitoring device along with the water level rising process by using an industrial camera. And recording the change condition of readings of the pressure sensor, the displacement sensor, the soil pressure sensor, the strain sensor and the pore water pressure sensor along with the rising of the water level.
7) And standing for a set time after the water level in the model box reaches the designed water level height. And continuously shooting the change of the position of the model soil displacement monitoring device along with time by using an industrial camera. The changes over time of the readings of the pressure sensor, displacement sensor, soil pressure sensor, strain sensor, and pore water pressure sensor are recorded.
8) And pumping out the water in the model box to the designed water level by using a water injection pumping system. And continuously shooting the position change of the model soil displacement monitoring device along with the water level descending process by using an industrial camera. Recording the change of readings of the pressure sensor, the displacement sensor, the soil pressure sensor, the strain sensor and the pore water pressure sensor along with the water level drop.
9) And storing the images and the data, and finishing the test equipment.
10 PIV technology is used for processing the test image, and a vector diagram of soil displacement around the tunnel model is obtained.
11 Analyzing the data and vector diagram, thereby obtaining the related law of tunnel deformation caused by groundwater level variation.
Further, in the step 1), a sand cushion layer with the thickness of 10cm is uniformly filled at the bottom of the model box, and the sand cushion layer is solidified for 24 hours by self weight.
Further, in the step 4), the injected model soil is self-consolidated for 1 month.
Further, in step 7), the water level in the mold box reaches the designed water level height and then stands for 10 days.
The technical effects of the invention are undoubted:
A. the tunnel deformation process caused by the underground water level change can be truly simulated;
B. the change rule of the buoyancy of the tunnel model, the vertical displacement of the tunnel model, the strain of the tunnel model, the displacement field of soil around the tunnel, the soil pressure around the tunnel model and the pore water pressure around the tunnel model can be accurately measured when the underground water level changes;
C. the system is reasonable in arrangement, convenient in test operation, low in cost and high in reliability.
Drawings
FIG. 1 is a schematic diagram of a model test apparatus;
FIG. 2 is a schematic diagram of a model box structure;
FIG. 3 is a schematic diagram of a tunnel model connection relationship;
FIG. 4 is a schematic view of a tunnel fixture;
FIG. 5 is a schematic diagram of a pressure monitoring device;
FIG. 6 is a schematic view of a structure of a fixing rod;
FIG. 7 is a schematic diagram of a strain sensor layout position;
FIG. 8 is a schematic view of a soil pressure sensor layout position;
FIG. 9 is a schematic diagram of a pore water pressure sensor layout position;
FIG. 10 is a diagram of a stress analysis of a tunnel model when the groundwater level rises;
FIG. 11 is a diagram of a stress analysis of a tunnel model when the groundwater level is unchanged;
FIG. 12 is a graph of a stress analysis of a tunnel model as the groundwater level drops.
In the figure: model soil accommodation space S, model box 1, model box main body 101, sand cushion 102, permeable curtain 103, geotextile 104, tunnel model 2, tunnel fixing device 3, bracket 301, upright post 3011, cross beam 3012, cantilever longitudinal beam 3013, U-shaped bracket 302, dowel 303, fixing rod 304, rod body 3041, locking portion 3042, pressure monitoring device 4, foam board 401, pressure sensor 402, displacement sensor 5, model soil displacement monitoring device 6, soil pressure sensor 7, strain sensor 8, water pipe 9, water pump 10, industrial camera 11, pore water pressure sensor 13.
Detailed Description
The present invention is further described below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples. Various substitutions and alterations are made according to the ordinary skill and familiar means of the art without departing from the technical spirit of the invention, and all such substitutions and alterations are intended to be included in the scope of the invention.
Example 1:
the embodiment provides a model test device for simulating tunnel deformation caused by underground water level fluctuation, which comprises a model box 1, a tunnel model 2, a tunnel fixing device 3, a monitoring system and a water injection pumping system.
The model box 1 comprises a model box main body 101, a sand cushion 102 and a permeable curtain 103. The model box main body 101 is a rectangular box body with an open upper end. The four side walls of the rectangular box body are a first side plate, a second side plate, a third side plate and a fourth side plate in sequence. The first side plate is a transparent side plate. The sandy soil cushion layer 102 is paved at the bottom of the inner cavity of the model box 1. The water permeable curtain 103 is of a U-shaped plate structure. The water permeable curtain 103 is vertically arranged in the inner cavity of the model box body 101. The water permeable curtain 103 is open towards the first side panel. Gaps exist between the three side plates of the water permeable curtain 103 and the corresponding side plates of the model box main body 101. The permeable curtain 103, the first side plate and the sand cushion 102 surround the model soil accommodating space S. Model soil is filled in the model soil accommodating space S. Geotextile 104 is also arranged between the sandy soil cushion layer 102 and the model soil.
The tunnel model 2 is a hollow cylinder. The tunnel model 2 is buried in model soil. The length direction of the tunnel model 2 is perpendicular to the plate surface of the first side plate. One end of the tunnel model 2 is tightly attached to the first side plate.
The tunnel fixing device 3 comprises a bracket 301, a U-shaped bracket 302, a dowel 303 and a fixing rod 304. The stand 301 comprises two height-adjustable uprights 3011 and a cross-beam. The two upright posts 3011 are respectively arranged on the upper surfaces of the second side plate and the fourth side plate. The cross beam includes a cross beam 3012 erected between two upright posts 3011, and overhanging stringers 3013 extending from the beams of the cross beam 3012. The longitudinal direction of the cantilever stringers 3013 is parallel to the longitudinal direction of the tunnel model 2. The U-shaped bracket 302 is disposed on the upper surface of the cross-beam 3012. The U-shaped bracket 302 has a top wall and two side walls. A hole for passing the dowel 303 is formed in the center of the cross beam 3012. After passing through the corresponding hole, the dowel 303 is fixedly connected with the tunnel model 2 at the lower end. The cantilever longitudinal beam 3013 is provided with a hole through which the fixing rod 304 passes. The fixing lever 304 includes a lever body 3041 and a locking portion 3042. The locking portion 3042 is provided on the shaft 3041. The shaft 3041 passes through the corresponding hole. The locking portion 3042 is placed on the cantilever side member 3013. The lower end of the shaft 3041 is fixedly connected with the tunnel model 2.
The monitoring system comprises a pressure monitoring device 4, a displacement sensor 5, a model soil displacement monitoring device 6, a soil pressure sensor 7, a strain sensor 8, an industrial camera 11 and a pore water pressure sensor 13. The pressure monitoring device 4 comprises a foam board 401 and a pressure sensor 402. The pressure sensor 402 is disposed on the lower surface of the top wall of the U-shaped bracket 302. The foam board 401 is connected to a pressure sensor 402. The upper end of the dowel 303 is connected to a foam deck 401. The displacement sensor 5 is arranged at the top end of the fixed rod 304. The model soil displacement monitoring device 6 is embedded in the model soil around the tunnel model 2 and is closely attached to the first side plate. The soil pressure sensor 7 and the pore water pressure sensor 13 are arranged on the outer wall of the tunnel model 2. The strain sensors 8 are arranged on the inner wall as well as on the outer wall of the tunnel model 2. The industrial camera 11 is arranged outside the mould box 1. The photographing direction of the industrial camera 11 is toward the first side plate.
In operation, the water injection and pumping system injects or pumps water into the gap between the water permeable curtain 103 and the model box body 101. The tunnel model 2 moves with the water level change. The monitoring system acquires the change data and images of the tunnel model 2 and the surrounding soil displacement field and the stress field. And obtaining related rules of tunnel deformation caused by ground water level fluctuation through analyzing the data and the images.
The embodiment can truly simulate the tunnel deformation process caused by the underground water level fluctuation, and can accurately measure the change of the displacement field and the stress field of the tunnel and surrounding soil bodies when the underground water level fluctuation occurs. The embodiment has low cost and wide application prospect.
Example 2:
the main structure of this embodiment is the same as that of embodiment 1, wherein the first side plate is made of plexiglass. The tunnel model 2 is made of light plastic.
Example 3:
the main structure of this embodiment is the same as that of embodiment 1, wherein the water injection pumping system comprises a plurality of water pipes 9 and a water pump 10. One end of the water pipe 9 is connected with the water pump 10, and the other end extends into a gap between the water permeable curtain 103 and the model box main body 101.
Example 4:
the main structure of this embodiment is the same as that of embodiment 1, wherein the outer walls of the tunnel model 2, the dowel bar 303 and the fixing bar 304 are uniformly coated with silicone grease.
Example 5:
referring to fig. 1, the embodiment provides a model test device for simulating tunnel deformation caused by groundwater level fluctuation, which comprises a model box 1, a tunnel model 2, a tunnel fixing device 3, a monitoring system and a water injection pumping system.
Referring to fig. 2, the model box 1 includes a model box body 101, a sand bed layer 102, and a water permeable curtain 103. The model box main body 101 is a rectangular box body with an open upper end. The four side walls of the rectangular box body are a first side plate, a second side plate, a third side plate and a fourth side plate in sequence. The first side plate is a transparent side plate. The first side plate is made of organic glass. The sandy soil cushion layer 102 is paved at the bottom of the inner cavity of the model box 1. The water permeable curtain 103 is of a U-shaped plate structure. The water permeable curtain 103 is vertically arranged in the inner cavity of the model box body 101. The water permeable curtain 103 is open towards the first side panel. Gaps exist between the three side plates of the water permeable curtain 103 and the corresponding side plates of the model box main body 101. The permeable curtain 103, the first side plate and the sand cushion 102 surround the model soil accommodating space S. Model soil is filled in the model soil accommodating space S. Geotextile 104 is also arranged between the sandy soil cushion layer 102 and the model soil.
The tunnel model 2 is a hollow cylinder. The tunnel model 2 is made of light plastic. The tunnel model 2 is buried in model soil. The length direction of the tunnel model 2 is perpendicular to the plate surface of the first side plate. One end of the tunnel model 2 is tightly attached to the first side plate.
Referring to fig. 3 and 4, the tunnel fixing device 3 includes a bracket 301, a U-shaped bracket 302, a dowel 303, and two fixing bars 304. The stand 301 comprises two height-adjustable uprights 3011 and a cross-beam. The two upright posts 3011 are respectively arranged on the upper surfaces of the second side plate and the fourth side plate. The cross beam includes a cross beam 3012 erected between two upright posts 3011, and overhanging stringers 3013 extending from the beams of the cross beam 3012. The longitudinal direction of the cantilever stringers 3013 is parallel to the longitudinal direction of the tunnel model 2. The U-shaped bracket 302 is disposed on the upper surface of the cross-beam 3012. The U-shaped bracket 302 has a top wall and two side walls. A hole for passing the dowel 303 is formed in the center of the cross beam 3012. After passing through the corresponding hole, the dowel 303 is fixedly connected with the tunnel model 2 at the lower end. Two holes for the fixing rods 304 to pass through are formed in the cantilever longitudinal beams 3013. Referring to fig. 6, the fixing lever 304 includes a lever body 3041 and a locking portion 3042. The locking portion 3042 is provided on the shaft 3041. The shaft 3041 passes through the corresponding hole. The locking portion 3042 is placed on the cantilever side member 3013. The lower end of the shaft 3041 is fixedly connected with the tunnel model 2. The outer walls of the tunnel model 2, the dowel bar 303 and the fixed bar 304 are uniformly coated with silicone grease.
The monitoring system comprises a pressure monitoring device 4, a displacement sensor 5, a model soil displacement monitoring device 6, a soil pressure sensor 7, a strain sensor 8, an industrial camera 11 and a pore water pressure sensor 13. Referring to fig. 5, the pressure monitoring device 4 includes a foam board 401 and a pressure sensor 402. The pressure sensor 402 is disposed on the lower surface of the top wall of the U-shaped bracket 302. The foam board 401 is connected to a pressure sensor 402. The upper end of the dowel 303 is connected to a foam deck 401. The displacement sensor 5 is arranged at the top end of the fixed rod 304. In this embodiment, the model soil displacement monitoring device 6 adopts special monitoring points. The model soil displacement monitoring device 6 is embedded in the model soil around the tunnel model 2 and is closely attached to the first side plate. Referring to fig. 7, 8 and 9, the soil pressure sensor 7 and the pore water pressure sensor 13 are disposed on the outer wall of the tunnel model 2. The strain sensors 8 are arranged on the inner wall as well as on the outer wall of the tunnel model 2. The industrial camera 11 is arranged outside the mould box 1. The photographing direction of the industrial camera 11 is toward the first side plate.
The water injection and pumping system comprises a plurality of water pipes 9 and a water pump 10. One end of the water pipe 9 is connected with the water pump 10, and the other end extends into a gap between the water permeable curtain 103 and the model box main body 101.
In operation, the water injection and pumping system injects or pumps water into the gap between the water permeable curtain 103 and the model box body 101. As the groundwater level changes, the tunnel model 2 moves, resulting in a movement of the dowel 303 and the fixation 304 connected to the tunnel model 2. Dowel 303 transmits the resultant force experienced by tunnel model 2 through foam deck 401 to pressure sensor 402, such that pressure sensor 402 is indicative of the magnitude of the resultant force experienced by tunnel model 2. The displacement sensor 5 reflects the change in the vertical displacement of the tunnel model 2 by monitoring the change in the displacement of the fixing rod 304. Along with the movement of the tunnel model 2, the positions of the special monitoring points buried around the tunnel model 2 also change, and a vector diagram of soil displacement around the tunnel model can be obtained through PIV image processing technology. By recording the data changes of the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13, the changes of the soil pressure, the pore water pressure and the self strain around the tunnel model 2 are obtained.
And carrying out stress analysis on the tunnel structure model: the tunnel model is subjected to dead weight W of the tunnel model in a soil layer, the outer wall of the tunnel model is subjected to soil pressure P and buoyancy F of groundwater b And tunnel model outer wall friction force f. The resultant force F experienced by the tunnel model can be measured by the pressure monitoring system. The circumferential soil pressure P applied to the tunnel model can be obtained through the soil pressure sensor. The water pressure P born by the outer wall of the tunnel model can be obtained through the gap water pressure sensor w . According to the stress analysis, horizontal components of the circumferential soil pressure P at two sides of the tunnel model are mutually offset. The vertical component W of the circumferential soil pressure P can be obtained through analysis and calculation s . The side wall friction force f born by the tunnel model is provided by the soil pressure P born by the outer wall of the tunnel model, the circumferential outer wall friction force born by the tunnel model can be obtained through the formula f=μP, and the force analysis shows that the friction force fwater of the outer wall of the tunnel modelThe bisectors are mutually offset, and the vertical component f of the circumferential outer wall friction force can be obtained through analysis and calculation v 。
The coefficient of friction is typically measured by measuring the angle of the ramp down. The operation method is that a container filled with model soil is reversely buckled on a plastic plate which is made of the same material as the model material of the tunnel structure, then the plastic plate is gradually inclined, and when the container filled with the model soil starts to slide downwards, the inclination angle alpha is recorded, and the friction coefficient mu=tan alpha.
By analysis, as shown in fig. 10, when the groundwater level rises, the tunnel model is subjected to buoyancy:
W+F-W s +f v ＝F b
by analysis, as shown in fig. 11, when the groundwater level is lowered, the tunnel model is subjected to buoyancy:
W+F-W s -f v ＝F b
by analysis, as in fig. 12, when the groundwater level stabilizes, the tunnel model is subjected to buoyancy:
W+F-W s ＝F b
example 6:
the present embodiment provides a test method using any one of the model test apparatuses for simulating tunnel deformation caused by groundwater level fluctuation described in embodiments 1 to 5, comprising the steps of:
1) A sand cushion 102 is filled in the bottom of the model box main body 101, and is self-consolidated for a set time.
2) Geotextile 104 and water permeable curtain 103 are arranged on sandy soil bedding layer 102.
3) And filling model soil to a designed height in layers in the model soil accommodating space S. The tunnel model 2 is embedded and fixedly connected with the tunnel fixing device 3. And continuously filling the model soil to the designed height of the soil layer. And arranging a monitoring system in the filling process.
4) The water is injected into the gap between the water permeable curtain 103 and the model box body 101 to a designed water level using the water injection pumping system. And (5) carrying out self-weight consolidation on the water-injected model soil for a set time.
5) Data of the pressure sensor 402 and the displacement sensor 5 are recorded as initial data. The initial position of the model soil displacement monitoring device 6 is photographed using the industrial camera 11.
6) The water is injected into the gap between the water permeable curtain 103 and the model box body 101 to a designed water level using the water injection pumping system. The industrial camera 11 is used for continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level rising process. The change of the readings of the pressure sensor 402, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13 with the rise of the water level is recorded.
7) And standing for a set time after the water level in the model box 1 reaches the designed water level height. The industrial camera 11 is used to continuously capture the change in position of the model soil displacement monitoring device 6 over time. The changes over time of the readings of the pressure sensor 402, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8, and the pore water pressure sensor 13 are recorded.
8) The water in the model tank 1 is pumped to a design water level using a water injection pumping system. The industrial camera 11 is used for continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level descending process. The changes in the readings of the pressure sensor 402, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8, and the pore water pressure sensor 13 with the decrease in water level are recorded.
9) And storing the images and the data, and finishing the test equipment.
10 PIV technology is used for processing the test image, and a vector diagram of soil displacement around the tunnel model 2 is obtained.
11 Analyzing the data and vector diagram, thereby obtaining the related law of tunnel deformation caused by groundwater level variation.
Example 7:
the embodiment provides a test method using any one of the model test devices for simulating tunnel deformation caused by groundwater level fluctuation according to embodiment 5, comprising the following steps:
1) The mold box 1, the tunnel mold 2 and the tunnel fixing device 3 are manufactured according to the design dimensions.
2) The mold box 1, the tunnel mold 2 and the tunnel fixture 3 are cleaned and wiped clean with a dry towel.
3) And uniformly filling a 10cm thick sand cushion layer 102 at the bottom of the model box 1, and carrying out self-weight consolidation for 24 hours.
4) Geotextile 104 and water permeable curtain 103 are laid on sandy soil bedding layer 102.
5) The water pump 10, the industrial camera 11 and the water pipe 9 are arranged and adjusted.
6) And filling model soil to a designed height in layers in the model soil accommodating space S. The tunnel model 2 is embedded and fixed by the dowel 303 and the fixing rod 304, so that the top end of the dowel 303 is contacted with the bottom surface of the foam board 401, and one end of the tunnel model 2 is tightly attached to the first side board. And then the model soil is filled up to the designed height of the soil layer. And the model soil displacement monitoring device 6 is buried in the filling process, and the model soil displacement monitoring device 6 is clung to the first side plate, so that the model soil displacement monitoring device 6 can be observed through the first side plate.
7) And water is slowly injected into the model box 1 at a constant speed to a designed water level through the water pipe 9 by using the water pump 10, and the water injection speed is determined according to test requirements. The injected model soil was consolidated by itself for 1 month.
8) After consolidation is completed, data of the pressure monitoring device 4, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8, and the pore water pressure sensor 13 are recorded as initial data. The position of the model soil displacement monitoring device 6 is photographed using the industrial camera 11 as an initial position of the model soil displacement monitoring device 6.
9) And water is slowly injected into the model box 1 at a constant speed to a designed water level through the water pipe 9 by using the water pump 10, and the water injection speed is determined according to test requirements. The industrial camera 11 is used for continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level rising process. The changes of the data readings of the pressure monitoring device 4, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13 along with the rising of the water level are recorded.
10 Standing for 10 days after the water level in the model box 1 reaches the designed water level. The industrial camera 11 is used to continuously capture the change in position of the model soil displacement monitoring device 6 over time. The change of the data readings of the pressure monitoring device 4, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13 with time is recorded.
11 Water in the model box 1 is slowly pumped out to the designed water level at a constant speed through the water pipe 9 by using the water pump 10, and the pumping speed is determined according to the test requirement. The industrial camera 11 is used for continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level descending process. The changes of the data readings of the pressure monitoring device 4, the displacement sensor 5, the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13 with the water level drop are recorded.
12 Storing the image and data, and finishing the test equipment.
13 PIV technology is used for processing the test image, and a vector diagram of soil displacement around the high tunnel model 2 is obtained.
14 Analyzing the data and vector diagram, thereby obtaining the related law of tunnel deformation caused by groundwater level variation.
Claims (6)
1. The utility model provides a model test device that simulation groundwater level change arouses tunnel deformation which characterized in that: the device comprises a model box (1), a tunnel model (2), a tunnel fixing device (3), a monitoring system and a water injection pumping system;
the model box (1) comprises a model box main body (101), a sand cushion layer (102) and a permeable curtain (103); the model box main body (101) is a rectangular box body with an open upper end; the four side walls of the rectangular box body are sequentially provided with a first side plate, a second side plate, a third side plate and a fourth side plate; the first side plate is a transparent side plate; the first side plate is made of organic glass; the sand cushion (102) is paved at the bottom of the inner cavity of the model box (1); the water permeable curtain (103) is of a U-shaped plate structure; the permeable curtain (103) is vertically arranged in the inner cavity of the model box main body (101); the opening of the water permeable curtain (103) faces to the first lateral plate; gaps exist between the three side plates of the permeable curtain (103) and the corresponding side plates of the model box main body (101); the permeable curtain (103), the first side plate and the sand cushion layer (102) surround a model soil accommodating space (S); model soil is filled in the model soil accommodating space (S); geotextile (104) is also arranged between the sandy soil cushion layer (102) and the model soil;
the tunnel model (2) is a hollow cylinder; the tunnel model (2) is made of light plastic; the tunnel model (2) is buried in model soil; the length direction of the tunnel model (2) is perpendicular to the plate surface of the first side plate; one end of the tunnel model (2) is clung to the first side plate;
the tunnel fixing device (3) comprises a bracket (301), a U-shaped bracket (302), a dowel bar (303) and a plurality of fixing bars (304); the bracket (301) comprises two upright posts (3011) with adjustable height and a cross beam; two stand columns (3011) are respectively arranged on the upper surfaces of the second side plate and the fourth side plate; the cross beam comprises a cross beam (3012) erected between two upright posts (3011), and an overhanging longitudinal beam (3013) extending from a beam body of the cross beam (3012); the length direction of the cantilever longitudinal beam (3013) is parallel to the length direction of the tunnel model (2); the U-shaped bracket (302) is arranged on the upper surface of the beam (3012); the U-shaped bracket (302) has a top wall and two side walls; a hole for a dowel bar (303) to pass through is formed in the center of the cross beam (3012); after passing through the corresponding holes, the dowel bars (303) are fixedly connected with the tunnel model (2) at the lower ends; a plurality of holes for the fixing rods (304) to pass through are formed in the cantilever longitudinal beams (3013); the fixed rod (304) comprises a rod body (3041) and a clamping part (3042); the locking part (3042) is arranged on the rod body (3041); the shaft (3041) passes through the corresponding hole; the clamping part (3042) is placed on the cantilever longitudinal beam (3013); the lower end of the rod body (3041) is fixedly connected with the tunnel model (2);
the monitoring system comprises a pressure monitoring device (4), a displacement sensor (5), a model soil displacement monitoring device (6), a soil pressure sensor (7), a strain sensor (8), an industrial camera (11) and a pore water pressure sensor (13); the pressure monitoring device (4) comprises a foam board (401) and a pressure sensor (402); the pressure sensor (402) is arranged on the lower surface of the top wall of the U-shaped bracket (302); the foam board (401) is connected with a pressure sensor (402); the upper end of the dowel bar (303) is connected with the foam plate (401); the displacement sensor (5) is arranged at the top end of the fixed rod (304); the model soil displacement monitoring device (6) is embedded in the model soil around the tunnel model (2) and clings to the first side plate; the soil pressure sensor (7) and the pore water pressure sensor (13) are arranged on the outer wall of the tunnel model (2); the strain sensor (8) is arranged on the inner wall and the outer wall of the tunnel model (2); the industrial camera (11) is arranged outside the model box (1); the shooting direction of the industrial camera (11) faces to the first side plate;
the water injection and pumping system comprises a plurality of water pipes (9) and a water pump (10); one end of the water pipe (9) is connected with the water pump (10), and the other end of the water pipe stretches into a gap between the water permeable curtain (103) and the model box main body (101);
when in work, the water injection pumping system injects water or pumps water into the gap between the water permeable curtain (103) and the model box main body (101); the tunnel model (2) moves along with the change of the water level; the monitoring system acquires the change data and images of the tunnel model (2) and the surrounding soil displacement field and the stress field; and obtaining related rules of tunnel deformation caused by ground water level fluctuation through analyzing the data and the images.
2. The model test device for simulating tunnel deformation caused by groundwater level fluctuation according to claim 1, wherein: and the outer walls of the tunnel model (2), the dowel bar (303) and the fixed bar (304) are uniformly coated with silicone grease.
3. A test method using the model test apparatus for simulating tunnel deformation caused by groundwater level fluctuation according to claim 1, comprising the steps of:
1) Filling a sand cushion layer (102) at the bottom of the model box main body (101), and carrying out self-weight consolidation for a set time;
2) Geotextile (104) and permeable curtain (103) are arranged on the sandy soil cushion layer (102);
3) Filling model soil into the model soil accommodating space (S) in layers until the design height is reached; the tunnel model (2) is embedded and fixedly connected with the tunnel fixing device (3); continuously filling model soil to the designed soil layer height; arranging a monitoring system in the filling process;
4) Injecting water into a gap between the permeable curtain (103) and the model box main body (101) to a designed water level by using a water injection pumping system; the self-weight consolidation of the water-injected model soil is carried out for a set time;
5) Recording data of the pressure sensor (402) and the displacement sensor (5) as initial data; shooting an initial position of the model soil displacement monitoring device (6) by using an industrial camera (11);
6) Injecting water into a gap between the permeable curtain (103) and the model box main body (101) to a designed water level by using a water injection pumping system; continuously shooting the position change of the model soil displacement monitoring device (6) along with the water level rising process by using an industrial camera (11); recording the change condition of readings of a pressure sensor (402), a displacement sensor (5), a soil pressure sensor (7), a strain sensor (8) and a pore water pressure sensor (13) along with the rising of the water level;
7) Standing for a set time after the water level in the model box (1) reaches the designed water level height; continuously shooting the change of the position of the model soil displacement monitoring device (6) along with time by using an industrial camera (11); recording the time-dependent changes of the readings of the pressure sensor (402), the displacement sensor (5), the soil pressure sensor (7), the strain sensor (8) and the pore water pressure sensor (13);
8) Pumping water in the model box (1) to a designed water level by using a water injection pumping system; continuously shooting the position change of the model soil displacement monitoring device (6) along with the water level descending process by using an industrial camera (11); recording the change of readings of the pressure sensor (402), the displacement sensor (5), the soil pressure sensor (7), the strain sensor (8) and the pore water pressure sensor (13) along with the water level drop;
9) Storing images and data, and finishing test equipment;
10 Processing the test image by using PIV technology to obtain a vector diagram of soil displacement around the tunnel model (2);
11 Analyzing the data and vector diagram, thereby obtaining the related law of tunnel deformation caused by groundwater level variation.
4. A test method according to claim 3, wherein: in the step 1), a sand cushion layer (102) with the thickness of 10cm is uniformly filled at the bottom of the model box (1), and the sand cushion layer is solidified for 24 hours by self-weight.
5. A test method according to claim 3, wherein: in the step 4), the injected model soil is self-consolidated for 1 month.
6. A test method according to claim 3, wherein: in the step 7), the water level in the model box (1) reaches the designed water level height and stands for 10 days.
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