CN113358851A - Model test device and method for simulating tunnel deformation caused by underground water level change - Google Patents
Model test device and method for simulating tunnel deformation caused by underground water level change 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 change. The model test device comprises a model box, a tunnel model, a tunnel fixing device, a monitoring system and a water injection and pumping system. The model test device can truly simulate the process of tunnel deformation caused by groundwater level change, and can accurately measure the change of a tunnel and a surrounding soil displacement field and a stress field when the groundwater level changes. 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 change.
Background
With the development of urbanization process in China and the appearance of super-large cities with large economic scale and strong aggregation, 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. However, flood disasters such as mountain torrents, waterlogging, river floods and the like frequently occur in recent years in China, and great influence is generated on normal use of underground structures. Therefore, the research on the action mechanism of the water level change on the underground structure has very important practical significance.
At present, simplified still water buoyancy is often adopted in engineering design as the designed buoyancy of an underground structure, and the buoyancy borne by the underground structure in actual engineering is more complex. In practical engineering, factors influencing the underground structure such as buoyancy and soil permeability coefficient, underground water seepage field, complex building environment around the underground structure and the like are closely related. Therefore, considering the influence of water level change on the buoyancy of the underground structure and researching the action mechanism of the underground structure is beneficial to optimizing the buoyancy design.
In the existing research, most scholars only carry out buoyancy model tests on simple underground structures, and do not consider the change rule of soil displacement fields around the underground structures floating along with underground water levels.
Therefore, it is necessary to develop a test device capable of monitoring the buoyancy of the tunnel and the displacement field of the surrounding soil body along with the change of the water level and a using method thereof.
Disclosure of Invention
The invention aims to provide a model test device for simulating tunnel deformation caused by underground water level change and a test method thereof, 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 the deformation of the tunnel caused by the change of the underground water level comprises a model box, a tunnel model, a tunnel fixing device, a monitoring system and a water injection and 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 laid 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 curtain permeates water is towards the first curb plate. Gaps exist between the three side plates of the water permeable curtain and the corresponding side plates of the model box main body. And the permeable curtain, the first side plate and the sand cushion layer are laminated to enclose a model soil accommodating space S. And model soil is filled in the model soil accommodating space S. And a geotextile is also 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 tightly attached to the first side plate.
The tunnel fixing device comprises a support, a U-shaped bracket, a dowel bar and a plurality of fixing rods. The support comprises two upright columns with adjustable height and a cross beam. The two upright posts 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 the two upright posts and a cantilever longitudinal beam extending from the 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 the dowel bars penetrate through the corresponding holes, the lower ends of the dowel bars are fixedly connected with the tunnel model. A plurality of holes for the fixing rods to penetrate through are formed in the cantilever longitudinal beam. The fixing rod comprises a rod body and a clamping part. The clamping part is arranged on the rod body. The shaft passes through the corresponding hole. The locking part is placed on the cantilever 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 plate 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 the 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 fixing rod. The model soil displacement monitoring device is embedded in the model soil around the tunnel model and is tightly attached to the first side plate. And the soil pressure sensor and the pore water pressure sensor are arranged on the outer wall of the tunnel model. The strain sensors are arranged on the inner wall and the outer wall of the tunnel model. The industrial camera is arranged outside the mold box. The shooting direction of the industrial camera faces the first side plate.
When the model box is in work, the water injection and pumping system injects water or pumps water into a gap between the water permeable curtain and the model box main body. The tunnel model moves as the water level changes. The monitoring system obtains the change data and images of the tunnel model and the displacement field and the stress field of the surrounding soil body. And obtaining the relevant rule of tunnel deformation caused by underground water level change by analyzing the data and the image.
Further, the first side plate is made of organic glass. The tunnel model is made of light plastics.
Further, the water injection and 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 extends into a gap between the permeable curtain and the model box main body.
Furthermore, silicone grease is uniformly coated on the outer walls of the tunnel model, the dowel bar and the fixed rod.
The invention also discloses a test method of the model test device for simulating tunnel deformation caused by groundwater level change, which comprises the following steps:
1) and filling a sand cushion layer at the bottom of the model box main body, and solidifying for a set time by self weight.
2) And arranging the geotextile and the permeable curtain on the sandy soil cushion layer.
3) And filling the model soil in the model soil accommodating space S to a design height in a layered manner. And embedding the tunnel model and fixedly connecting the tunnel model 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 (3) injecting water into the gap between the permeable curtain and the model box main body to a designed water level by using a water injection and pumping system. And (5) solidifying the model soil injected with water for a set time by self weight.
5) The 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 (3) injecting water into the gap between the permeable curtain and the model box main body to a designed water level by using a water injection and 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 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 position change of the model soil displacement monitoring device with an industrial camera along with the time. And recording the changes of readings of the pressure sensor, the displacement sensor, the soil pressure sensor, the strain sensor and the pore water pressure sensor along with time.
8) And pumping water in the model box to a 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 in the descending process by using an industrial camera. And recording the indication changes of the pressure sensor, the displacement sensor, the soil pressure sensor, the strain sensor and the pore water pressure sensor along with the drop of the water level.
9) And storing the images and data, and arranging the test equipment.
10) And processing the test image by using a PIV technology to obtain a vector diagram of the displacement of the soil around the tunnel model.
11) And analyzing and sorting the obtained data and vector diagram to obtain the relevant rule of tunnel deformation caused by underground water level change.
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 model soil injected with water is solidified for 1 month under the dead weight.
Further, in the step 7), standing for 10 days after the water level in the model box reaches the designed water level height.
The technical effects of the invention are undoubted:
A. the tunnel deformation process caused by the change of the underground water level can be truly simulated;
B. the method can accurately measure the change rules of the buoyancy of the tunnel model, the vertical displacement of the tunnel model, the self strain of the tunnel model, the displacement field of the soil body around the tunnel, the soil pressure around the tunnel model and the pore water pressure around the tunnel model when the underground water level changes;
C. the system is reasonable in arrangement, convenient to test and operate, low in cost and high in reliability.
Drawings
FIG. 1 is a schematic structural diagram of a model test apparatus;
FIG. 2 is a schematic view of a mold box structure;
FIG. 3 is a schematic diagram of a tunnel model connection relationship;
FIG. 4 is a schematic structural view of a tunnel fixture;
FIG. 5 is a schematic structural view of a pressure monitoring device;
FIG. 6 is a schematic view of a fixing rod structure;
FIG. 7 is a schematic diagram of the layout position of a strain sensor;
FIG. 8 is a schematic view of the arrangement position of the soil pressure sensors;
FIG. 9 is a schematic diagram of the arrangement position of a pore water pressure sensor;
FIG. 10 is a graph of analysis of the stress on the tunnel model as the groundwater level rises;
FIG. 11 is a graph of the tunnel model force analysis with the groundwater level unchanged;
FIG. 12 is a graph of the tunnel model force analysis as the groundwater level drops.
In the figure: the device comprises a model soil accommodating space S, a model box 1, a model box main body 101, a sand cushion layer 102, a permeable curtain 103, geotechnical cloth 104, a tunnel model 2, a tunnel fixing device 3, a support 301, a column 3011, a cross beam 3012, an overhanging longitudinal beam 3013, a U-shaped bracket 302, a dowel bar 303, a fixing bar 304, a bar body 3041, a clamping part 3042, a pressure monitoring device 4, a foam plate 401, a pressure sensor 402, a displacement sensor 5, a model soil displacement monitoring device 6, a soil pressure sensor 7, a strain sensor 8, a water pipe 9, a water pump 10, an industrial camera 11 and a pore water pressure sensor 13.
Detailed Description
The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.
Example 1:
the embodiment provides a model test device for simulating tunnel deformation caused by underground water level change, which comprises a model box 1, a tunnel model 2, a tunnel fixing device 3, a monitoring system and a water injection and pumping system.
The mold box 1 comprises a mold box body 101, a sand bed 102 and a water permeable curtain 103. The mold 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 sand cushion 102 is laid on the bottom of the inner cavity of the mold 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 opening of the water permeable curtain 103 faces the first side plate. Gaps are reserved 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 layer 102 surround a model soil accommodating space S. And model soil is filled in the model soil accommodating space S. A 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 bar 303 and a fixing bar 304. The support 301 comprises two height-adjustable columns 3011 and a cross beam. The two upright posts 3011 are respectively disposed 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 the 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 disposed on the upper surface of the cross bar 3012. The U-shaped bracket 302 has a top wall and two side walls. A hole for the dowel bar 303 to pass through is formed in the center of the cross beam 3012. And after the dowel bar 303 penetrates through the corresponding hole, the lower end of the dowel bar is fixedly connected with the tunnel model 2. The cantilever longitudinal beam 3013 is provided with a hole through which the fixing rod 304 passes. The fixing lever 304 includes a shaft 3041 and a stopper 3042. The locking portion 3042 is provided on the shaft 3041. The shaft 3041 passes through the corresponding hole. The stop 3042 rests on the cantilevered 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 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 bar 303 is connected with a foam board 401. The displacement sensor 5 is disposed at the top end of the fixing 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 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 mold box 1. The shooting direction of the industrial camera 11 is towards the first side plate.
When the water injection and water pumping system works, water is injected or pumped into a gap between the water permeable curtain 103 and the model box main body 101. The tunnel model 2 moves as the water level changes. The monitoring system obtains the change data and images of the tunnel model 2 and the displacement field and the stress field of the surrounding soil body. And obtaining the relevant rule of tunnel deformation caused by underground water level change by analyzing the data and the image.
The method can truly simulate the process of tunnel deformation caused by underground water level change, and can accurately measure the change of the displacement field and the stress field of the tunnel and the surrounding soil body when the underground water level changes. The embodiment has low cost and wide application prospect.
Example 2:
the main structure of the present embodiment is the same as that of embodiment 1, wherein the first side plate is made of organic glass. The tunnel model 2 is made of light plastic.
Example 3:
the main structure of the present embodiment is the same as that of embodiment 1, wherein 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 thereof extends into the 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 rod 304 are uniformly coated with silicone grease.
Example 5:
referring to fig. 1, the present embodiment provides a model test apparatus for simulating tunnel deformation caused by groundwater level fluctuation, which includes a model box 1, a tunnel model 2, a tunnel fixing device 3, a monitoring system and a water injection and pumping system.
Referring to fig. 2, the mold box 1 includes a mold box body 101, a sand bed 102, and a water permeable curtain 103. The mold 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 sand cushion 102 is laid on the bottom of the inner cavity of the mold 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 opening of the water permeable curtain 103 faces the first side plate. Gaps are reserved 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 layer 102 surround a model soil accommodating space S. And model soil is filled in the model soil accommodating space S. A 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 bar 303 and two fixing bars 304. The support 301 comprises two height-adjustable columns 3011 and a cross beam. The two upright posts 3011 are respectively disposed 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 the 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 disposed on the upper surface of the cross bar 3012. The U-shaped bracket 302 has a top wall and two side walls. A hole for the dowel bar 303 to pass through is formed in the center of the cross beam 3012. And after the dowel bar 303 penetrates through the corresponding hole, the lower end of the dowel bar is fixedly connected with the tunnel model 2. Two holes for the fixing rod 304 to pass through are formed in the cantilever longitudinal beam 3013. Referring to fig. 6, the fixing lever 304 includes a shaft 3041 and a grip 3042. The locking portion 3042 is provided on the shaft 3041. The shaft 3041 passes through the corresponding hole. The stop 3042 rests on the cantilevered longitudinal beam 3013. The lower end of the rod body 3041 is fixedly connected with the tunnel model 2. And silicone grease is uniformly coated on the outer walls of the tunnel model 2, the dowel bar 303 and the fixing rod 304.
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 bar 303 is connected with a foam board 401. The displacement sensor 5 is disposed at the top end of the fixing rod 304. In this embodiment, the model soil displacement monitoring device 6 adopts a special monitoring point. 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. Referring to fig. 7, 8 and 9, the soil pressure sensor 7 and the pore water pressure sensor 13 are installed 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 mold box 1. The shooting direction of the industrial camera 11 is towards the first side plate.
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 thereof extends into the gap between the water permeable curtain 103 and the model box main body 101.
When the water injection and water pumping system works, water is injected or pumped into a gap between the water permeable curtain 103 and the model box main body 101. As the ground water level is continuously changed, the tunnel model 2 is moved, thereby causing the dowel bars 303 and the fixing bars 304 connected to the tunnel model 2 to be moved. The dowel bars 303 transmit the resultant force to which the tunnel model 2 is subjected to the pressure sensor 402 through the foam board 401, so that the pressure sensor 402 displays the magnitude of the resultant force to which the tunnel model 2 is subjected. The displacement sensor 5 reflects the change of the vertical displacement of the tunnel model 2 by monitoring the change of the displacement of the fixing rod 304. Along with the movement of the tunnel model 2, the positions of special monitoring points embedded around the tunnel model 2 can also change, and a vector diagram of the displacement of the soil body around the tunnel model can be obtained through a PIV image processing technology. The changes of the soil pressure around the tunnel model 2, the pore water pressure and the self strain are obtained by recording the data changes of the soil pressure sensor 7, the strain sensor 8 and the pore water pressure sensor 13.
Carrying out stress analysis on the tunnel structure model: the tunnel model is subjected to the dead weight W of the tunnel model in the soil layer, the soil pressure P on the outer wall of the tunnel model and the buoyancy F of underground waterbAnd a tunnelAnd f, model outer wall friction force. The resultant force F to which the tunnel model is subjected can be measured by the pressure monitoring system. The annular soil pressure P borne by the tunnel model can be obtained through the soil pressure sensor. The water pressure P borne by the outer wall of the tunnel model can be obtained through the gap water pressure sensorw. Through stress analysis, the horizontal components of the annular soil pressure P at the two sides of the tunnel model are mutually offset. The vertical component W of the circumferential soil pressure P can be obtained by analysis and calculations. The lateral wall frictional force f that the tunnel model received receives soil pressure P by the tunnel model outer wall and provides, can obtain the hoop outer wall frictional force that the tunnel model received through formula f ═ mu P, can know through the atress analysis that tunnel model outer wall frictional force f horizontal component offsets each other, can obtain the vertical component f of hoop outer wall frictional force through analysis and calculationv。
The coefficient of friction is typically measured by the angle of the slope glide. The operation method comprises the steps of reversely buckling the container filled with the model soil on a plastic plate made of the same material as the model soil of the tunnel structure, gradually inclining the plastic plate, and recording the inclination angle alpha when the container filled with the model soil starts to slide downwards, wherein the friction coefficient mu is tan alpha.
By analysis, as shown in fig. 10, when the groundwater level rises, the tunnel model is subjected to buoyancy:
W+F-Ws+fv＝Fb
by analysis, as in fig. 11, as the groundwater level descends, the tunnel model is subject to buoyancy:
W+F-Ws-fv＝Fb
by analysis, as in fig. 12, when the groundwater level is stable, the tunnel model is subjected to buoyancy:
W+F-Ws＝Fb
example 6:
the embodiment provides a test method of a model test device for simulating tunnel deformation caused by groundwater level fluctuation in any one of embodiments 1 to 5, which comprises the following steps:
1) the bottom of the mold box body 101 is filled with a sand cushion 102 and is fixed for a set time by its own weight.
2) Geotextile 104 and water permeable curtain 103 are arranged on the sandy soil mat 102.
3) And filling the model soil in the model soil accommodating space S to a design height in a layered manner. 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) And (3) injecting water into the gap between the water permeable curtain 103 and the model box main body 101 to a designed water level by using a water injection and water pumping system. And (5) solidifying the model soil injected with water for a set time by self weight.
5) The 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) And (3) injecting water into the gap between the water permeable curtain 103 and the model box main body 101 to a designed water level by using a water injection and water pumping system. And continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level rising process by using the industrial camera 11. And 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 rise.
7) And standing for a set time after the water level in the model box 1 reaches the designed water level height. The position of the model soil displacement monitoring device 6 is continuously photographed over time using the industrial camera 11. The readings of the pressure sensor 402, displacement sensor 5, soil pressure sensor 7, strain sensor 8 and pore water pressure sensor 13 are recorded as a function of time.
8) The water in the model box 1 is pumped out 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 6 along with the water level descending process by using the industrial camera 11. 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 as the water level decreases.
9) And storing the images and data, and arranging the test equipment.
10) And processing the test image by using a PIV technology to obtain a vector diagram of the displacement of the soil around the tunnel model 2.
11) And analyzing and sorting the obtained data and vector diagram to obtain the relevant rule of tunnel deformation caused by underground water level change.
Example 7:
the embodiment provides a test method of the model test device for simulating tunnel deformation caused by groundwater level fluctuation in embodiment 5, which comprises the following steps:
1) the model box 1, the tunnel model 2 and the tunnel fixture 3 are manufactured to design dimensions.
2) The mold box 1, tunnel mold 2 and tunnel fixture 3 are cleaned and wiped clean with a dry towel.
3) A sand cushion layer 102 with the thickness of 10cm is evenly filled at the bottom of the model box 1 and is solidified for 24 hours by self weight.
4) Geotextile 104 and water permeable curtain 103 are laid on the sandy soil cushion layer 102.
5) The water pump 10, the industrial camera 11 and the water pipe 9 are arranged and adjusted.
6) And filling the model soil in the model soil accommodating space S to a design height in a layered manner. The tunnel model 2 is embedded and fixed through the dowel bar 303 and the fixing rod 304, so that the top end of the dowel bar 303 is ensured to be 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 plate. And then the model soil is continuously filled to the designed height of the soil layer. Fill the in-process and bury model soil displacement monitoring devices 6 simultaneously to make model soil displacement monitoring devices 6 hug closely first curb plate, guarantee to see through first curb plate and can observe model soil displacement monitoring devices 6.
7) And slowly injecting water into the model box 1 to a designed water level at a constant speed by using a water pump 10 through a water pipe 9, wherein the water injection speed is determined according to the test requirements. And (5) solidifying the model soil injected with water for 1 month by self weight.
8) After the consolidation is completed, the 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 slowly injecting water into the model box 1 to a designed water level at a constant speed by using a water pump 10 through a water pipe 9, wherein the water injection speed is determined according to the test requirements. And continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level rising process by using the industrial camera 11. And recording the data display 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 change of the water level.
10) And standing for 10 days after the water level in the model box 1 reaches the designed water level height. The position of the model soil displacement monitoring device 6 is continuously photographed over time using the industrial camera 11. And recording 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 change of time.
11) And (3) pumping water in the model box 1 to a designed water level slowly at a constant speed by using a water pump 10 through a water pipe 9, wherein the pumping speed is determined according to the test requirement. And continuously shooting the position change of the model soil displacement monitoring device 6 along with the water level descending process by using the industrial camera 11. And recording 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 reduction of the water level.
12) And storing the images and data, and arranging the test equipment.
13) And (3) processing the test image by using a PIV technology to obtain a vector diagram of the displacement of the soil around the high tunnel model 2.
14) And analyzing and sorting the obtained data and vector diagram to obtain the relevant rule of tunnel deformation caused by underground water level change.
Claims (8)
1. The utility model provides a model test device that simulation ground water level change arouses tunnel deformation which characterized in that: the tunnel water injection and drainage system comprises a model box (1), a tunnel model (2), a tunnel fixing device (3), a monitoring system and a water injection and drainage 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 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 (102) is laid 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 main body (101); the opening of the water permeable curtain (103) faces the first side plate; 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 layer (102) enclose a model soil accommodating space (S); model soil is filled in the model soil accommodating space (S); a 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 vertical 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 support (301), a U-shaped bracket (302), a dowel bar (303) and a plurality of fixing rods (304); the support (301) comprises two upright posts (3011) with adjustable height 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 comprises a cross beam (3012) erected between two upright posts (3011) and an overhanging longitudinal beam (3013) extending from the 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 cross 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); the lower end of the dowel bar (303) is fixedly connected with the tunnel model (2) after passing through the corresponding hole; a plurality of holes for the fixing rods (304) to pass through are formed in the cantilever longitudinal beam (3013); the fixing rod (304) comprises a rod body (3041) and a clamping part (3042); the locking part (3042) is arranged on the shaft (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 plate (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 fixing rod (304); the model soil displacement monitoring device (6) is embedded in the model soil around the tunnel model (2) and is tightly 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 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;
when the model box works, the water injection and pumping system injects water or pumps water into a 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 change data and images of the tunnel model (2) and a displacement field and a stress field of surrounding soil; and obtaining the relevant rule of tunnel deformation caused by underground water level change by analyzing the data and the image.
2. The model test device for simulating the deformation of the tunnel caused by the variation of the underground water level as claimed in claim 1, wherein: the first side plate is made of organic glass; the tunnel model (2) is made of light plastics.
3. The model test device for simulating the deformation of the tunnel caused by the variation of the underground water level as claimed in claim 1, wherein: 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 extends into a gap between the permeable curtain (103) and the model box main body (101).
4. The model test device for simulating the deformation of the tunnel caused by the variation of the underground water level as claimed in claim 1, wherein: and silicone grease is uniformly coated on the outer walls of the tunnel model (2), the dowel bar (303) and the fixing rod (304).
5. A test method using the model test apparatus for simulating deformation of a tunnel caused by groundwater level fluctuation according to claim 1, comprising the steps of:
1) filling a sand cushion (102) at the bottom of the model box main body (101), and solidifying for a set time by self weight;
2) arranging a geotextile (104) and a water permeable curtain (103) on the sandy soil cushion (102);
3) filling model soil in the model soil accommodating space (S) to a design height in a layered manner; the tunnel model (2) is embedded and is fixedly connected with the tunnel fixing device (3); continuously filling the model soil to the designed height of the soil layer; 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 and pumping system; setting the self-weight consolidation time of the model soil injected with water;
5) recording data of the pressure sensor (402) and the displacement sensor (5) as initial data; shooting the 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 and 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 conditions 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 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 the time by using an industrial camera (11); recording the changes 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 time;
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 indication changes 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 drop of the water level;
9) storing the images and data, and arranging the test equipment;
10) processing the test image by using a PIV technology to obtain a vector diagram of the displacement of the soil around the tunnel model (2);
11) and analyzing and sorting the obtained data and vector diagram to obtain the relevant rule of tunnel deformation caused by underground water level change.
6. The test method according to claim 5, characterized in that: in the step 1), a sand cushion (102) with the thickness of 10cm is uniformly filled at the bottom of the model box (1) and is solidified for 24 hours by self weight.
7. The test method according to claim 5, characterized in that: in the step 4), the model soil injected with water is solidified for 1 month under the dead weight.
8. The test method according to claim 5, characterized in that: and 7), standing for 10 days after the water level in the model box (1) reaches the designed water level height.
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