CN108508189B - Test device and method for foundation pit damage caused by coupling action of seepage field and vibration field - Google Patents
Test device and method for foundation pit damage caused by coupling action of seepage field and vibration field Download PDFInfo
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Abstract
The invention discloses a test device and a test method for foundation pit damage caused by the coupling effect of a seepage field and a vibration field, wherein the test device comprises a foundation pit simulation system, a support simulation system, a water supply and drainage pipeline simulation system, a loading system and an electrical impedance imaging system, wherein the foundation pit simulation system simulates foundation pits and road surfaces adjacent to the foundation pits, the support simulation system simulates different foundation pit support structures, the water supply and drainage pipeline simulation system simulates leakage of water supply and drainage pipelines and whether the pipelines are pressurized or not, the loading system simulates vehicle vibration load, and the electrical impedance imaging system records three-dimensional images inside the soil and analyzes the evolution mechanism of cavities inside the soil. The test device simulates leakage of a water supply and drainage pipeline in a soil body and whether the pipeline is pressurized or not through a water supply and drainage pipeline simulation system, simulates vibration load of a vehicle through a loading system, and simulates influence on foundation pit damage under the coupling action of a seepage field and a vibration field through the combination of the seepage field and the vibration field.
Description
Technical Field
The invention relates to the field of geotechnical engineering, in particular to a test device and a test method for foundation pit damage caused by coupling action of a seepage field and a vibration field.
Background
With the high-speed development of the economy in China, the urban use is more and more intense, and the development of the urban underground space is quickened. In dense urban spaces, foundation pit engineering is often close to traffic channels, and vibration generated by vehicles flowing in a rough way can influence the stability of the foundation pit; complicated municipal pipelines exist around the foundation pit, and due to improper construction and the like, the water supply and drainage pipelines are broken and leaked, so that subsurface hidden soil holes are induced, meanwhile, the soil strength is greatly reduced, the stability and the surrounding environment of the foundation pit are greatly influenced, and a plurality of foundation pit accidents of instability and damage due to the reasons occur in China. Therefore, under the combined action of vehicle vibration load and water leakage of the water supply and drainage pipelines, the development rule of the hidden soil hole and the foundation pit soil deformation mechanism and foundation pit damage mechanism caused by the development rule are studied.
The foundation pit excavation causes uneven settlement of the foundation of the underground water supply and drainage pipeline around the foundation pit, or the underground water supply and drainage pipeline is directly damaged by rough construction, so that the pipeline is broken and water leakage is caused. Soil around the pipeline is soaked by the water leakage, and the soil strength is reduced. The seepage water seeps in the soil body to drive the soil body particles to migrate. The strength of the soil body is reduced and the soil body particles migrate to cause the generation of underground hidden soil holes. The dynamic load of the vehicle on the surface road causes the vibration of the underground soil body, and the expansion of the soil hole is aggravated, so that the damage of the foundation pit and the surrounding environment is caused. The influence of soil holes on pavement collapse is researched by the existing test device, and the influence of hidden soil holes caused by pipeline leakage on the stability of a foundation pit is not researched by the existing test device; the pipeline leakage causes the generation of soil holes, the dynamic load of the vehicle can aggravate the development of the soil holes, and no test device can consider the coupling effect of a vibration field and a leakage field. Therefore, the development of a test device for simulating the development of a hidden soil hole and the damage of a foundation pit caused by the coupling effect of a seepage field and a vibration field is particularly urgent and important.
Disclosure of Invention
The invention provides a test device and a test method for foundation pit damage caused by coupling action of a seepage field and a vibration field, which overcome the defects in the prior art.
One of the adopted technical schemes for solving the technical problems is as follows:
test device that seepage field and vibrating field coupling effect lead to foundation ditch destruction, its characterized in that: it comprises the following steps: the foundation pit simulation system simulates foundation pits and road surfaces adjacent to the foundation pits, the support simulation system simulates different foundation pit support structures, the water supply and drainage pipeline simulation system simulates leakage of the water supply and drainage pipeline in a soil body and whether the pipeline is pressurized or not, the loading system simulates vehicle vibration load, and the electrical impedance imaging system records three-dimensional view of the interior of the soil body and analyzes the evolution mechanism of a cavity in the soil body.
In a preferred embodiment: the foundation pit simulation system comprises an organic glass box, a test soil sample and a pavement slab, wherein one side in the organic glass box is provided with the test foundation pit and the test soil sample positioned at the bottom of the test foundation pit, the other side in the organic glass box is the filled test soil sample, and the pavement slab covers the top surface of the test soil sample at the side.
In a preferred embodiment: the electrical impedance imaging system comprises a power supply, an external current generator, a computer, an Arduino microcontroller, a multiplexer, digital acquisition equipment and a plurality of electrode tubes, wherein the computer controls the multiplexer through the Arduino microcontroller, the multiplexer is connected with the electrode tubes, the digital acquisition equipment is connected with the electrode tubes and the computer, the electrode tubes are inserted into test soil samples below a pavement slab through hollow conductive glass tubes, the external current generator applies a current field to one electrode tube, the digital acquisition equipment acquires voltage signals generated by other electrode tubes and transmits the voltage signals to the computer, and the computer obtains a tomographic image through an inversion algorithm.
In a preferred embodiment: the pavement slab comprises a first layer plate and a second layer plate which are arranged in an up-down laminating mode, wherein the first layer plate is a concrete slab or an asphalt concrete slab, and the second layer plate is a gravel layer.
In a preferred embodiment: the water supply and drainage pipeline simulation system comprises a water pump, a booster pump, a pipeline pressure sensor, a flowmeter, a silicone tube, a PVC pipe and a liquid storage tank, wherein two ends of the silicone tube are respectively connected with the water pump and the booster pump, the booster pump is connected with the water inlet end of the PVC pipe, the PVC pipe penetrates through a test soil sample below a road surface plate of the organic glass tank, the water outlet end of the PVC pipe is connected with the liquid storage tank, the flowmeter is arranged at the water inlet end of the PVC pipe, the pipeline pressure sensor is arranged at the water inlet end and the water outlet end of the PVC pipe, water leakage holes with different shapes, sizes and numbers are formed in the PVC pipe, and the water leakage holes are formed in the test soil sample below the road surface plate.
In a preferred embodiment: the loading system comprises a loading frame, a loading hammer for loading the road surface plate, a servo press for providing power for the loading hammer and a numerical control machine tool controller for setting a maximum load value, loading speed and loading frequency so as to control the servo press to drive the loading hammer to load out of a triangular wave-shaped dynamic load, wherein the servo press is arranged on the loading frame, the loading hammer is axially movably arranged on the loading frame and is in transmission connection with the servo press, and the bottom surface of the loading hammer corresponds to the road surface plate.
In a preferred embodiment: the number of the loading hammers is three, the loading hammers are arranged side by side, the bottom surfaces of the three loading hammers are overlapped with the road surface plate, and the number of the servo presses is three and is connected with the three loading hammers in a one-to-one correspondence manner.
In a preferred embodiment: the particle image testing system further comprises four digital cameras and a computer, wherein the four digital cameras are respectively arranged right in front of the four peripheral surfaces of the organic glass box, transparent glass paper which is uniformly arranged with black dots is stuck to the four peripheral surfaces of the organic glass box, the digital cameras shoot pictures, the pixel positions of each pixel point on the pictures are recorded by the computer, the displacement of each pixel point under a Cartesian coordinate system is converted by combining the black dots of the glass paper, and the deformation of a supporting structure and a soil body is observed and recorded, and the foundation pit damage development process is reproduced.
In a preferred embodiment: the system also comprises a solid particle analysis system for analyzing solid particles in the liquid at the water outlet of the PVC pipe, and the system comprises a laser particle analyzer and a particle counter, wherein the laser particle analyzer is used for measuring the particle size of the solid particles, and the particle counter is used for counting the particle number.
In a preferred embodiment: the support simulation system comprises wood sticks, wood strips, thin steel bars, thin steel wires, injectors, cement slurry and rubber tubes, wherein the wood sticks simulate row piles, the wood strips simulate crown beams and waist beams, the thin steel bars simulate soil nails, the thin steel wires simulate steel strands of anchor cables, and the injectors, the cement slurry and the rubber tubes simulate grouting.
The second technical scheme adopted for solving the technical problems is as follows: the test method for foundation pit damage caused by the coupling effect of the seepage field and the vibration field is characterized by comprising the following steps:
step 10, presetting jacks and hollow conductive glass tubes in an organic glass box, filling test soil samples into the organic glass box, and tamping properly; according to the test purpose, selecting road boards with different materials, and paving the road boards on a test soil sample at one side in the organic glass box;
step 20, mounting a water supply and drainage pipeline simulation system: PVC pipes with different sizes, shapes and numbers of water leakage holes are selected according to the test purpose, the PVC pipes pass through the organic glass box through the insertion holes, the PVC pipes are positioned right below the pavement slab, and then the water pump, the booster pump, the pipeline pressure sensor, the flowmeter, the silica gel pipe and the liquid storage box are installed and connected;
step 30, mounting an electrical impedance imaging system: inserting an electrode tube into a hollow conductive glass tube, and then installing and connecting a power supply, an external current generator, a computer, an Arduino microcontroller, a multiplexer and digital acquisition equipment;
step 40, installation of a loading system: installing a loading frame, a loading hammer, a servo press and a numerical control machine tool controller so that the bottom surface of the loading hammer is opposite to the pavement slab;
step 50, selecting different supporting structures according to the test purpose;
step 60, simulating foundation pit excavation: digging a test soil sample at one side in the organic glass box body to form a test foundation pit, reserving the test soil sample at the pit bottom, and cleaning the soil sample at the inner side wall of the organic glass box body;
step 70, simulating water leakage of the pipeline: starting a water pump, adjusting a booster pump, pressurizing the inside of the PVC pipe, observing the pressure value in the pipe through a pipeline pressure sensor, and adjusting a flowmeter to set pipeline flow;
step 80, simulating the dynamic load of the vehicle: selecting the number and the positions of the loading hammers according to the test purpose, starting a servo press, and setting the maximum loading load, the loading speed and the loading interval through a numerical control machine controller so as to drive the loading hammers to load the triangular wave load;
step 90, performing observation analysis through an electrical impedance imaging system: an external current generator is arranged, a current field is applied to a test soil sample through a certain electrode tube at intervals, the three-dimensional view of the interior of the soil body is recorded through a computer, and the evolution mechanism of the hole in the soil body is analyzed;
observation analysis is performed by a particle image testing system: and (3) taking pictures at intervals by a digital camera, recording the pixel positions of each pixel point on the pictures, converting the displacement of each pixel point under a Cartesian coordinate system by combining a computer program with black dots of glass paper to observe and record the deformation of a supporting structure and a soil body, reproducing the foundation pit damage development process, and analyzing the foundation pit damage mechanism. Observation analysis was performed by a solid particle analysis system: sampling is carried out at intervals by using a container at the water discharge port of the PVC pipe, and then the particle size and the number of the solid particles are measured by using a laser particle analyzer and a particle counter so as to analyze the influence of the size, the shape and the number of the water leakage holes on the soil particle loss around the water leakage holes.
In a preferred embodiment: in step 30, when the electrode tube is inserted into the hollow conductive glass tube, the bottom of the electrode tube is not contacted with the bottom of the hollow conductive glass tube, and the top of the electrode tube is fixed on the hollow conductive glass tube by using a watertight plastic cap.
Compared with the background technology, the technical proposal has the following advantages:
1. the test device simulates leakage of a water supply and drainage pipeline in a soil body and whether the pipeline is pressurized or not through a water supply and drainage pipeline simulation system, simulates vibration load of a vehicle through a loading system, and simulates influence on foundation pit damage under the coupling action of a seepage field and a vibration field through the combination of the two; the electrical impedance imaging system can record three-dimensional scenes in the soil body and analyze the evolution mechanism of the cavity in the soil body, is an improved, simplified, low-energy-consumption and flexible in precision control, is suitable for a three-dimensional electrical impedance imaging system on a laboratory scale, is particularly suitable for reproducing the internal scenes of the soil body, and can obtain a three-dimensional cavity image in the soil body with high precision.
2. The electrical impedance imaging system is a technology for imaging resistivity characteristics of conductive materials, an external current generator is used for applying an electric current field to a test soil sample through one electrode tube at intervals, then a digital acquisition device is used for acquiring voltages of the test soil sample measured through other electrode tubes and transmitting the voltages to a computer, and the computer obtains a tomographic image through an inversion algorithm.
3. The booster pump can regulate the pressure in the PVC pipe, and then the pressure value in the pipe is detected by the pipeline pressure sensor; and the flow in the PVC pipe is set by adjusting the flowmeter, and the water leakage condition of the water supply and drainage pipeline can be simulated more truly by changing the pressure in the pipe and the flow, so that the result obtained by the test device is more accurate.
4. The number of the loading hammers is three and the loading hammers are arranged side by side, the bottom surfaces of the three loading hammers are overlapped with the pavement slab, the using number of the loading hammers can be selected according to the test purpose, and if the influence of single-point vibration on the foundation pit is tested, one loading hammer is used; if the impact of multipoint vibrations on the foundation pit is tested, 2 or 3 loading hammers are used.
5. The digital camera shoots pictures, pixel positions of each pixel point on the pictures are recorded through the computer, the displacement of each pixel point under a Cartesian coordinate system is converted by combining black dots of the glass paper, so that deformation of a supporting structure and a soil body is observed and recorded, the foundation pit damage development process is reproduced, and the particle image testing system can obtain high-precision and quantitative foundation pit damage development process images.
6. The particle size and the number of the solid particles are measured by a laser particle analyzer and a particle counter so as to analyze the influence of the size, the shape and the number of the water leakage holes on the loss of soil particles around the water leakage holes, and further observe the influence of the seepage effect on foundation pit damage.
7. The support simulation system comprises wood sticks, wood strips, thin steel bars, thin steel wires, injectors, cement slurry and rubber tubes, and can simulate three different support structures of soil nailing wall support, cantilever row pile support and anchor cable row pile combined support.
Drawings
The invention is further described below with reference to the drawings and examples.
FIG. 1 is a schematic diagram showing the overall structure of a test apparatus according to a preferred embodiment.
FIG. 2 shows a schematic cross-sectional view A-A of FIG. 1.
FIG. 3 shows a schematic cross-sectional view of B-B of FIG. 1.
Fig. 4 is a schematic diagram showing the assembly of the electrode tube and the hollow conductive glass tube.
Fig. 5 is a schematic sectional view showing a soil nailing wall supporting structure.
Fig. 6 shows a schematic cross-sectional view of a cantilever row pile support structure.
Fig. 7 is a schematic cross-sectional view of the anchor line-pile combined support structure.
Detailed Description
The invention ignores the space effect of the foundation pit based on the consideration of the least adverse condition, and simulates one side of the foundation pit, which is close to a road and has complex underground pipeline condition.
Referring to fig. 1 to 7, a preferred embodiment of a test apparatus for foundation pit damage caused by coupling action of a seepage field and a vibration field is provided, which comprises a foundation pit simulation system, a support simulation system, a water supply and drainage pipeline simulation system, a loading system and an electrical impedance imaging system.
The foundation pit simulation system simulates a foundation pit and a road surface adjacent to the foundation pit.
In this embodiment, the foundation pit simulation system includes an organic glass box 10, a test soil sample 13 and a pavement slab 11, wherein one side in the organic glass box 10 is provided with a test foundation pit 12 and a test soil sample positioned at the bottom of the test foundation pit 12, the other side in the organic glass box is a filled test soil sample 13, and the pavement slab 11 covers the top surface of the test soil sample 13 at the side.
In this example, the organic glass box 10 is a cube with a length, a width and a height of 2m, and is formed by using five organic glass plates through neutral glass glue, and the top is opened.
In this embodiment, as shown in fig. 1, the test pit is provided on the left side of the plexiglass box 10, and the test pit road is provided on the right side of the plexiglass box 10. The front and back sides of the organic glass box 10 are respectively provided with jacks, the jacks are positioned below the pavement slab 11, and the number of the jacks can be multiple and are arranged at intervals up and down. The right side of the organic glass case 10 is provided with through holes, and three rows of through holes, each row of which is provided with 3-15 different holes, are provided. In addition, transparent hollow conductive glass tubes 14 with two non-closed ends are arranged, the number of the glass tubes 14 is the same as that of the through holes and corresponds to that of the through holes one by one, in the embodiment, the diameter of the hollow conductive glass tubes 14 is set to be 6mm, and the glass tubes 14 are inserted into the test soil sample 13 through the through holes and are fixed with the organic glass plate at the side through neutral glass cement.
In this embodiment, the pavement slab 11 includes a first layer and a second layer which are arranged in a vertically laminated manner, the first layer is a concrete slab or asphalt slab and has a thickness of 20mm, and the second layer is a gravel layer and has a thickness of 40mm. According to the test requirement, if a rigid pavement is tested, a pavement slab of a concrete slab and a gravel layer is adopted, and if a flexible pavement is tested, a pavement slab of an asphalt concrete slab and a gravel layer is adopted.
The water supply and drainage pipeline simulation system simulates leakage of water supply and drainage pipelines in soil and whether the pipelines are pressurized or not. In the embodiment, the water supply and drainage pipeline simulation system comprises a water pump 20, a booster pump 21, a pipeline pressure sensor 22, a flowmeter 23, a silica gel pipe 24, a PVC pipe 25 and a liquid storage tank 26, wherein two ends of the silica gel pipe 24 are respectively connected with the water pump 20 and the booster pump 21; the booster pump 21 is connected with the water inlet end of the PVC pipe 25, and the applied pressure range is 0-0.5Mpa; the PVC pipe 25 passes through the test soil sample 13 of the plexiglass box 10 and the water outlet end thereof is connected with the liquid storage box 26; the flowmeter 23 is installed at the water inlet end of the PVC pipe 25, can adjust the water flow speed, and can accurately measure the flow rate in unit time; the two pipeline pressure sensors 22 are arranged at the water inlet end and the water outlet end of the PVC pipe 25 respectively, namely the two pipeline pressure sensors 22 are respectively positioned at the front side and the rear side of the organic glass box 10; and the PVC pipe 25 is provided with a plurality of different PVC pipes, each PVC pipe is provided with water leakage holes with different shapes, sizes or numbers, and the water leakage holes are positioned in the test soil sample 13 below the pavement slab.
In this embodiment, as shown in fig. 1, the water outlet end of the PVC pipe 25 is inserted into the test soil sample 13 below the pavement slab through the insertion hole on the rear side of the plexiglass box 10, and is penetrated out through the insertion hole on the front side of the plexiglass box 10 and then connected to the liquid storage box 26. The jacks are arranged at intervals up and down, so that the PVC pipe 25 can be inserted by selecting the positions of the jacks according to test requirements. The outer diameter of the PVC pipe 25 can be set to 15mm, 20mm, 40mm, and the wall thickness of the PVC pipe can be set to 1mm, 1.5mm, 2.5mm.
The support simulation system simulates different foundation pit support structures.
In this embodiment, the support simulation system comprises a wood rod, a wood strip, a thin steel bar, a thin steel wire, an injector, cement slurry and a rubber tube, wherein the wood rod simulates a row pile, the wood strip simulates a crown beam and a waist beam, the thin steel bar simulates a soil nail, the thin steel wire simulates a steel strand of an anchor cable, and the injector, the cement slurry and the rubber tube simulate grouting.
As shown in fig. 5, selecting thin steel bars 70 with the diameter of 2mm to be inserted into a test soil sample, wherein the insertion angle of the thin steel bars 70 is 20 degrees, the horizontal spacing and the vertical spacing of adjacent thin steel bars 70 are 150mm, selecting thin steel wires with the diameter of 0.5mm to be woven into a steel bar net with square grids of 25mm x 25mm, arranging the steel bar net on a slope, brushing cement slurry, and simulating soil nailing wall support; or, as shown in fig. 6, selecting round wood sticks 71, inserting round wood sticks 71 with three specifications of 60mm, 80mm and 100mm into a test soil sample at intervals, wherein the horizontal intervals are 100mm, 140mm and 180mm respectively, inserting the bottom ends of the round wood sticks 71 into the depth of 250mm below the surface of a foundation pit, fixing the top ends of all inserted round wood sticks 71 by using thin wood strips with the width of 60mm and the thickness of 10mm, and driving the thin wood strips into the top ends of the round wood sticks 71 by nails to simulate cantilever row pile supports with three different pile diameters and different pile intervals respectively; or, selecting a log rod with the diameter of 18mm, drilling towards a test soil sample 13, twisting the log rod into steel wires with the drilling angle of 20 degrees, penetrating the steel wires into the drilling holes together with grouting rubber pipes, wherein the steel wires are 1000mm long, a section of the steel wires with the diameter of 500mm is wrapped by a preservative film, the rest section is not wrapped, the section wrapped by the preservative film is placed on the outward side of the drilling holes, cement slurry is injected by a syringe, the rubber pipes are pulled out while grouting until the drilling holes are filled, anchor ropes 72 with the diameters of 5m, 5m and 180mm are used for simulating the free sections, and the anchor sections are formed in a thin wood strip with the thickness of 10mm, each hole is formed at intervals of 150mm, one end of the simulated anchor rope free section is inserted into each hole, the thin wood strip is fixed on the top end of the log rod 71 by using strong glue, the thin wood strip is fixed on the top end of the log rod 71 of the simulated row pile, and the simulated anchor rope row pile is supported in a combined mode, as shown in fig. 7.
The loading system simulates the vehicle vibration load.
In this embodiment, the loading system includes a loading frame 30, a loading hammer 31 for loading the road surface board 11, a servo press for providing power for the loading hammer 31, and a numerical control machine controller for setting a maximum load value, a loading speed and a loading frequency to control the servo press to drive the loading hammer to load a triangle wave-shaped dynamic load, wherein the servo press is installed on the loading frame 30, the loading hammer 31 is axially movably installed on the loading frame 30 and is in transmission connection with the servo press, and the bottom surface of the loading hammer 31 corresponds to the road surface board 11.
In this embodiment, the number of loading hammers 31 is three, and the bottom surfaces of the three loading hammers 31 are overlapped with the road surface plate 11, and the number of servo presses is three and connected with the three loading hammers 31 in a one-to-one correspondence. The numerical control machine controller sets the axial pressure range of the loading hammer 31 to be 10-100KN and the loading frequency range to be 1-20Hz so as to realize the loading purpose of the triangular wave dynamic load.
The electrical impedance imaging system records three-dimensional scenes in the soil body and analyzes the evolution mechanism of the cavity in the soil body.
In this embodiment, the electrical impedance imaging system includes a power source, an external current generator 40, a computer 41, an Arduino microcontroller, a multiplexer, a digital acquisition device and a plurality of electrode tubes 42, the computer 41 controls the multiplexer through the Arduino microcontroller, the multiplexer is connected with the plurality of electrode tubes 42, the digital acquisition device is connected with the electrode tubes 42 and the computer 41, the electrode tubes 42 are inserted into the test soil sample 13 through the hollow conductive glass tube 14, the external current generator applies a current field to the test soil sample 13 through one of the electrode tubes 42, the digital acquisition device acquires voltage signals generated by the test soil sample 13 measured by the other electrode tubes 42 and transmits the voltage signals to the computer 41, and the computer 41 obtains a tomographic image through an inversion algorithm.
In this embodiment, the number of electrode tubes 42 is the same as and corresponds to the number of hollow conductive glass tubes 14, and the electrode tubes are 5mm in diameter and inserted into the glass tubes 14 one by one. The bottom of the electrode tube 42 is not contacted with the bottom of the hollow conductive glass tube 14, and the top of the electrode tube 42 is fixed on the hollow conductive glass tube 14 by a watertight plastic cap 43.
The electrical impedance imaging system can record three-dimensional scenes in the soil body and analyze the evolution mechanism of the cavity in the soil body, is an improved, simplified, low-energy-consumption and flexible in precision control, is suitable for a three-dimensional electrical impedance imaging system on a laboratory scale, is particularly suitable for reproducing the internal scenes of the soil body, and can obtain a three-dimensional cavity image in the soil body with high precision.
In this embodiment, the test device further includes a particle image test system, which includes four digital cameras 50 and a computer, the four digital cameras 50 are respectively arranged right in front of the four peripheral surfaces of the organic glass box 10, transparent glass paper uniformly arranged with black dots is adhered to the four peripheral surfaces of the organic glass box 10, the digital cameras 50 take pictures and record pixel positions of each pixel point on the pictures by the computer, and convert the displacement of each pixel point under a cartesian coordinate system by combining with the black dots of the glass paper, so as to observe and record the deformation of the supporting structure and soil body, and reproduce the foundation pit damage development process.
In this embodiment, the test device further includes a solid particle analysis system for analyzing solid particles in the liquid at the water outlet of the PVC pipe 25, which includes a laser particle analyzer 60 and a particle counter 61, where the laser particle analyzer 60 is used for measuring the particle size of the solid particles, and the laser particle analyzer 60 performs measurement analysis by the principle that the light irradiates the particles to scatter, diffract, and scattered light intensity are all related to the particle size; the particle counter 61 is used to count the number of particles, which is counted by a photoresist method.
In this embodiment, this test device still includes the miniature manometer that is used for measuring the log rod surface test soil sample pressure of cantilever row stake supporting construction, and this miniature manometer is equidistant to be pasted on log rod surface. The miniature pressure gauge measures the pressure of the test soil sample by a resistance method so as to observe the distribution condition of the pressure of the test soil sample, the pressure acting on the supporting structure and the change thereof.
The test device simulates leakage of a water supply and drainage pipeline in a soil body and whether the pipeline is pressurized or not through a water supply and drainage pipeline simulation system, simulates vibration load of a vehicle through a loading system, and simulates influence on foundation pit damage under the coupling action of a seepage field and a vibration field through the combination of the seepage field and the vibration field.
The test method for foundation pit damage caused by the coupling effect of the seepage field and the vibration field comprises the following steps:
step 10, presetting jacks and hollow conductive glass tubes 14 in the organic glass box 10, filling test soil samples into the organic glass box 10, and tamping properly; according to the test purpose, selecting road boards 11 with different materials, and paving the road boards 11 on a test soil sample at one side in the organic glass box 10;
step 20, mounting a water supply and drainage pipeline simulation system: PVC pipes 25 with different water leakage hole sizes, shapes and numbers are selected according to the test purpose, the PVC pipes 25 penetrate through the organic glass box 10 through insertion holes, the PVC pipes 25 are positioned right below the pavement slab 11, and then the water pump 20, the booster pump 21, the pipeline pressure sensor 22, the flowmeter 23, the silica gel pipe 24 and the liquid storage box 26 are installed and connected;
step 30, mounting an electrical impedance imaging system: the electrode tube 42 is inserted into the hollow conductive glass tube 14, and then a power supply, an external current generator 40, a computer 41, an Arduino microcontroller, a multiplexer and digital acquisition equipment are installed and connected; in this embodiment, in step 30, when the electrode tube 42 is inserted into the hollow conductive glass tube 14, the bottom of the electrode tube 42 is not in contact with the bottom of the hollow conductive glass tube 14, and the top of the electrode tube 42 is fixed to the hollow conductive glass tube 14 by the watertight plastic cap 43.
Step 40, installation of a loading system: mounting the loading frame 30, the loading hammer 31, the servo press and the numerical control machine tool controller so that the bottom surface of the loading hammer 31 is opposite to the pavement slab 11;
step 50, selecting different supporting structures according to the test purpose; in this embodiment, the support simulation system selects the cantilever pile support structure shown in fig. 6;
step 60, simulating foundation pit excavation: excavating a test soil sample on one side in the organic glass box body 10 to form a test foundation pit 12, reserving the test soil sample at the pit bottom, and cleaning the soil sample on the inner side wall of the organic glass box body 10;
step 70, simulating water leakage of the pipeline: starting the water pump 20, regulating the booster pump 21, pressurizing the inside of the PVC pipe 25, observing the pressure value in the pipe through the pipe pressure sensor 22, and regulating the flowmeter 23 to set the pipe flow;
step 80, simulating the dynamic load of the vehicle: selecting the number and the positions of the loading hammers 31 according to the test purpose, starting the servo press, and setting the maximum loading load, the loading speed and the loading interval through a numerical control machine controller so as to drive the loading hammers to load the triangular wave load;
step 90, performing observation analysis through an electrical impedance imaging system: an external current generator 40 is arranged, a current field is applied to the test soil sample 13 through one electrode tube 42 at intervals, the three-dimensional scene inside the soil body is recorded through a computer 41, and the evolution mechanism of the hole in the soil body is analyzed;
observation analysis is performed by a particle image testing system: the digital camera shoots pictures at intervals to record pixel positions of each pixel point on the pictures, converts displacement of each pixel point under a Cartesian coordinate system through a computer program and combining black dots of glass paper to observe and record deformation of a supporting structure and a soil body, reproduces a foundation pit damage development process, and analyzes a foundation pit damage mechanism;
observation analysis was performed by a solid particle analysis system: samples are taken from the container at intervals at the water outlet of the PVC pipe 25, and the particle size and the number of the solid particles are measured by the laser particle sizer 60 and the particle counter 61 so as to analyze the influence of the size, the shape and the number of the water leakage holes on the soil particle loss around the water leakage holes.
In this embodiment, in step 90, the pressure of the test soil sample on the log rod surface of the cantilever pile supporting structure can be measured by a micro-manometer, so as to observe the distribution of the pressure of the test soil sample and the pressure and the change of the pressure acting on the supporting structure.
The foregoing description is only illustrative of the preferred embodiments of the present invention, and therefore should not be taken as limiting the scope of the invention, for all changes and modifications that come within the meaning and range of equivalency of the claims and specification are therefore intended to be embraced therein.
Claims (7)
1. Test device that seepage field and vibrating field coupling effect lead to foundation ditch destruction, its characterized in that: it comprises the following steps: the system comprises a foundation pit simulation system, a support simulation system, a water supply and drainage pipeline simulation system, a loading system and an electrical impedance imaging system, wherein the foundation pit simulation system simulates foundation pits and road surfaces adjacent to the foundation pits, the support simulation system simulates different foundation pit support structures, the water supply and drainage pipeline simulation system simulates leakage and pipeline pressure or non-pressure in a soil body, the loading system simulates vehicle vibration load, and the electrical impedance imaging system records three-dimensional view of the interior of the soil body and analyzes the evolution mechanism of a cavity in the soil body;
the foundation pit simulation system comprises an organic glass box, a test soil sample and a pavement slab, wherein one side in the organic glass box is provided with the test foundation pit and the test soil sample positioned at the bottom of the test foundation pit, the other side in the organic glass box is provided with the filled test soil sample, and the pavement slab covers the top surface of the test soil sample at the side;
the electrical impedance imaging system comprises a power supply, an external current generator, a computer, an Arduino microcontroller, a multiplexer, digital acquisition equipment and a plurality of electrode tubes, wherein the computer controls the multiplexer through the Arduino microcontroller, the multiplexer is connected with the electrode tubes, the digital acquisition equipment is connected with the electrode tubes and the computer, the electrode tubes are inserted into a test soil sample below a pavement slab through hollow conductive glass tubes, the external current generator applies a current field to one of the electrode tubes, the digital acquisition equipment acquires voltage signals generated by the other electrode tubes and transmits the voltage signals to the computer, and the computer acquires a tomographic image through an inversion algorithm;
the water supply and drainage pipeline simulation system comprises a water pump, a booster pump, a pipeline pressure sensor, a flowmeter, a silicone tube, a PVC pipe and a liquid storage tank, wherein two ends of the silicone tube are respectively connected with the water pump and the booster pump, the booster pump is connected with the water inlet end of the PVC pipe, the PVC pipe penetrates through a test soil sample below a road surface plate of the organic glass tank, the water outlet end of the PVC pipe is connected with the liquid storage tank, the flowmeter is arranged at the water inlet end of the PVC pipe, the pipeline pressure sensor is arranged at the water inlet end and the water outlet end of the PVC pipe, water leakage holes with different shapes, sizes and numbers are formed in the PVC pipe, and the water leakage holes are formed in the test soil sample below the road surface plate;
the support simulation system comprises wood sticks, wood strips, thin steel bars, thin steel wires, injectors, cement slurry and rubber tubes, wherein the wood sticks simulate row piles, the wood strips simulate crown beams and waist beams, the thin steel bars simulate soil nails, the thin steel wires simulate steel strands of anchor cables, and the injectors, the cement slurry and the rubber tubes simulate grouting;
the loading system comprises a loading frame, a loading hammer for loading the road surface plate, a servo press for providing power for the loading hammer and a numerical control machine tool controller for setting a maximum load value, loading speed and loading frequency so as to control the servo press to drive the loading hammer to load out of a triangular wave-shaped dynamic load, wherein the servo press is arranged on the loading frame, the loading hammer is axially movably arranged on the loading frame and is in transmission connection with the servo press, and the bottom surface of the loading hammer corresponds to the road surface plate.
2. The test device for foundation pit damage caused by coupling action of seepage field and vibration field according to claim 1, wherein: the pavement slab comprises a first layer plate and a second layer plate which are arranged in an up-down laminating mode, wherein the first layer plate is a concrete slab or an asphalt concrete slab, and the second layer plate is a gravel layer.
3. The test device for foundation pit damage caused by coupling action of seepage field and vibration field according to claim 1, wherein: the number of the loading hammers is three, the loading hammers are arranged side by side, the bottom surfaces of the three loading hammers are overlapped with the road surface plate, and the number of the servo presses is three and is connected with the three loading hammers in a one-to-one correspondence manner.
4. The test device for foundation pit damage caused by coupling action of seepage field and vibration field according to claim 1, wherein: the particle image testing system further comprises four digital cameras and a computer, wherein the four digital cameras are respectively arranged right in front of the four peripheral surfaces of the organic glass box, transparent glass paper which is uniformly arranged with black dots is stuck to the four peripheral surfaces of the organic glass box, the digital cameras shoot pictures, the pixel positions of each pixel point on the pictures are recorded by the computer, the displacement of each pixel point under a Cartesian coordinate system is converted by combining the black dots of the glass paper, and the deformation of a supporting structure and a soil body is observed and recorded, and the foundation pit damage development process is reproduced.
5. The test device for foundation pit damage caused by coupling action of seepage field and vibration field according to claim 1, wherein: the system also comprises a solid particle analysis system for analyzing solid particles in the liquid at the water outlet of the PVC pipe, and the system comprises a laser particle analyzer and a particle counter, wherein the laser particle analyzer is used for measuring the particle size of the solid particles, and the particle counter is used for counting the particle number.
6. The test method for foundation pit damage caused by the coupling effect of the seepage field and the vibration field is characterized by comprising the following steps:
step 10, presetting jacks and hollow conductive glass tubes in an organic glass box, filling test soil samples into the organic glass box, and tamping properly; according to the test purpose, selecting road boards with different materials, and paving the road boards on a test soil sample at one side in the organic glass box;
step 20, mounting a water supply and drainage pipeline simulation system: PVC pipes with different sizes, shapes and numbers of water leakage holes are selected according to the test purpose, the PVC pipes pass through the organic glass box through the insertion holes, the PVC pipes are positioned right below the pavement slab, and then the water pump, the booster pump, the pipeline pressure sensor, the flowmeter, the silica gel pipe and the liquid storage box are installed and connected;
step 30, mounting an electrical impedance imaging system: inserting an electrode tube into a hollow conductive glass tube, and then installing and connecting a power supply, an external current generator, a computer, an Arduino microcontroller, a multiplexer and digital acquisition equipment;
step 40, installation of a loading system: installing a loading frame, a loading hammer, a servo press and a numerical control machine tool controller so that the bottom surface of the loading hammer is opposite to the pavement slab;
step 50, selecting different supporting structures according to the test purpose;
step 60, simulating foundation pit excavation: digging a test soil sample at one side in the organic glass box body to form a test foundation pit, reserving the test soil sample at the pit bottom, and cleaning the soil sample at the inner side wall of the organic glass box body;
step 70, simulating water leakage of the pipeline: starting a water pump, adjusting a booster pump, pressurizing the inside of the PVC pipe, observing the pressure value in the pipe through a pipeline pressure sensor, and adjusting a flowmeter to set pipeline flow;
step 80, simulating the dynamic load of the vehicle: selecting the number and the positions of the loading hammers according to the test purpose, starting a servo press, and setting the maximum loading load, the loading speed and the loading interval through a numerical control machine controller so as to drive the loading hammers to load the triangular wave load;
step 90, performing observation analysis through an electrical impedance imaging system: setting an external current generator, applying a current field to a test soil sample through one electrode tube at intervals, recording three-dimensional scenes inside the soil body through a computer, and analyzing the evolution mechanism of the hole in the soil body;
observation analysis is performed by a particle image testing system: the digital camera shoots pictures at intervals to record pixel positions of each pixel point on the pictures, converts displacement of each pixel point under a Cartesian coordinate system through a computer program and combining black dots of glass paper to observe and record deformation of a supporting structure and a soil body, reproduces a foundation pit damage development process, and analyzes a foundation pit damage mechanism;
observation analysis was performed by a solid particle analysis system: sampling is carried out at intervals by using a container at the water discharge port of the PVC pipe, and then the particle size and the number of the solid particles are measured by using a laser particle analyzer and a particle counter so as to analyze the influence of the size, the shape and the number of the water leakage holes on the soil particle loss around the water leakage holes.
7. The method for testing foundation pit damage caused by coupling action of seepage field and vibration field according to claim 6, wherein: in step 30, when the electrode tube is inserted into the hollow conductive glass tube, the bottom of the electrode tube is not contacted with the bottom of the hollow conductive glass tube, and the top of the electrode tube is fixed on the hollow conductive glass tube by using a watertight plastic cap.
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