CN112798418A - Experimental device for observe and measure stake soil interact of unsaturated soil - Google Patents
Experimental device for observe and measure stake soil interact of unsaturated soil Download PDFInfo
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- CN112798418A CN112798418A CN202110125434.4A CN202110125434A CN112798418A CN 112798418 A CN112798418 A CN 112798418A CN 202110125434 A CN202110125434 A CN 202110125434A CN 112798418 A CN112798418 A CN 112798418A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention relates to an experimental device for observing and measuring pile-soil interaction of unsaturated soil, and belongs to the technical field of pile-soil testing experiments. This experimental apparatus includes: the device comprises a pile body, a loading device, a transparent model box, a sensing system for monitoring the stress condition of the pile body and a PIV observation system; the transparent model box is internally provided with an unsaturated soil foundation, the pile body is vertically arranged, the lower end of the pile body is inserted into the unsaturated soil foundation, the loading device is arranged on the transparent model box, the output end of the loading device is connected with the upper end of the pile body and the unsaturated soil foundation, the input end of the sensing system is arranged on the pile body and in the unsaturated soil foundation, and the output end of the PIV observation system faces the transparent model box. The experimental device can observe and record displacement deformation of soil around the pile and various related parameter changes of the pile body under the conditions of vertical load, circulating vertical load action and the like, and is favorable for evaluating pile-soil interaction of unsaturated soil.
Description
Technical Field
The invention belongs to the technical field of pile soil testing experiments, and particularly relates to an experimental device for observing and measuring pile soil interaction of unsaturated soil.
Background
The prefabricated pile foundation is a deep foundation which is formed by connecting the tops of a plurality of piles into a whole through a bearing platform and bears dynamic and static loads together, and the piles are vertical or inclined foundation components arranged in soil. The prefabricated pile foundation is widely applied to the fields of various building foundations, bridges, pile bearing roads, wharf ports, ocean development engineering and the like nowadays.
The unsaturated soil is widely applied to engineering, the interaction mechanism of the precast pile and the unsaturated soil in the pile sinking and bearing capacity exerting processes is very complex, and the interaction mechanism of a pile-soil interface is a key scientific problem. Due to the influences of factors such as precipitation, evaporation and underground water level change, the prediction of post-construction settlement and uneven settlement of pile foundations and foundations in engineering often has a large difference from the actual situation. Therefore, adverse effects are brought to the long-term safe and stable operation of the construction engineering, and the interaction and research of the pile and unsaturated soil have important engineering significance.
The existing related researches do not visually observe the influence of displacement deformation generated by soil bodies and the interaction of pile soil when the pile soil interacts.
Therefore, a device capable of observing the interaction between unsaturated soil and piles is needed.
Disclosure of Invention
The invention provides an experimental device for observing and measuring pile-soil action in unsaturated soil, which can observe and record the displacement deformation of soil around a pile and the change conditions of various related parameters of a pile body under the conditions of vertical load, cyclic vertical load and the like, and is favorable for evaluating the pile-soil action of the unsaturated soil.
The technical scheme for solving the technical problems is as follows: an experimental apparatus for observing and measuring pile-soil interaction of unsaturated soil, comprising: the device comprises a pile body, a loading device, a transparent model box, a sensing system for monitoring the stress condition of the pile body and a PIV observation system;
the transparent model box is internally provided with an unsaturated soil foundation, the pile body is vertically arranged, the lower end of the pile body is inserted into the unsaturated soil foundation, the loading device is installed on the transparent model box, the output end of the loading device is connected with the upper end of the pile body and the unsaturated soil foundation, the input end of the sensing system is arranged on the pile body and in the unsaturated soil foundation, and the shooting end of the PIV observation system faces the transparent model box.
The invention has the beneficial effects that: the method can realize observation of the deformation process of the soil body, the formation development process of a shear band and the change of the displacement field of the soil body around the pile body in the whole process when the pile body bears the cyclic vertical load or the pile body and the soil body bear the static load in the loading process of the pile body, and can also realize acquisition and change detection of a series of mechanical parameters under various actions such as pile side resistance, pile end resistance, soil pressure, pore water pressure, surrounding pressure and the like at different positions away from the pile in the loading process of the pile body, when the pile body bears the cyclic load or the pile body and the soil body bear the static load and the like, and has important engineering significance for researching the interaction between the pile body and unsaturated soil.
On the basis of the technical scheme, the invention can be further improved as follows.
Further, the loading device includes the support body, be used for right the pile body applys the main jack of load and be used for right unsaturated soil foundation applys the time jack of load, the support body erects on the transparent model case, the main jack with time jack all connects on the support body, the output of main jack with the pile body is connected, the output of time jack with unsaturated soil foundation connects.
The beneficial effect of adopting the further scheme is that: the pile body and the unsaturated soil foundation can be loaded conveniently, and the real environment can be simulated.
Furthermore, the output end of the main jack is fixedly provided with a loading transfer plate, and the upper end of the pile body is fixedly connected with the loading transfer plate.
The beneficial effect of adopting the further scheme is that: the pile body is better driven to move, and load is applied to the pile body.
Furthermore, a soil body prestressed plate used for covering the unsaturated soil foundation is arranged in the transparent model box, and the output end of the secondary jack extends into the transparent model box and is connected with the soil body prestressed plate.
The beneficial effect of adopting the further scheme is that: the method is favorable for applying balanced load to the unsaturated soil foundation.
Further, the support body includes base, reaction frame and counter-force roof beam, transparent mold box connects on the base, the bottom of reaction frame with the base is connected, the counter-force roof beam is connected the top of reaction frame, the counter-force roof beam is located the vertical top of transparent mold box, main jack with inferior jack is all connected on the counter-force roof beam.
The beneficial effect of adopting the further scheme is that: the main jack and the secondary jack are supported and fixed conveniently.
Further, the sensing system comprises an axial force sensor, a dial indicator and a plurality of strain gauges, wherein the axial force sensor is connected with the top end of the main jack, the axial force sensor detects the applied force of the main jack, two ends of the dial indicator are respectively connected with the counter-force beam and the loading transfer plate, the dial indicator detects the displacement distance of the loading transfer plate, and the strain gauges are connected to the pile body at equal intervals along the length direction of the pile body.
The beneficial effect of adopting the further scheme is that: the stress condition of the pile body can be detected conveniently.
Further, the transparent model box comprises a transparent box body and a steel plate, the top end of the transparent box body is open, the steel plate is located in the transparent box body and fixedly connected with the inner wall of one side, and the steel plate is provided with a plurality of soil pressure boxes and a plurality of pore pressure sensors.
The beneficial effect of adopting the further scheme is that: the filling of unsaturated soil foundations is facilitated, and the shooting by a CCD camera is facilitated.
Further, be equipped with the drain pipe that is used for carminative blast pipe and is used for the drainage on the bottom lateral wall of transparent box, the one end of blast pipe with the inside intercommunication of transparent box, the one end of drain pipe with the inside intercommunication of transparent box, be equipped with on the blast pipe and be used for opening or closing the discharge valve of blast pipe, be equipped with on the drain pipe and be used for opening or closing the drain valve of drain pipe.
The beneficial effect of adopting the further scheme is that: the process of exhaust and drainage can be simulated, so that a real use environment is simulated.
Further, the inner wall of one side of the transparent box body, which is provided with the drain pipe, is provided with a surrounding pressure sensor for detecting the surrounding pressure of the unsaturated soil foundation;
the transparent model box, the pile body and the loading device are all arranged in the constant temperature and humidity box.
The beneficial effect of adopting the further scheme is that: so as to accurately measure the pressure change around the unsaturated soil foundation.
Further, the PIV observation system comprises a light source and a CCD camera, wherein the light source and the CCD camera are both positioned on the front side of the transparent model box, the light source irradiates light onto the transparent model box, and the CCD camera shoots the picture of the transparent model box.
The beneficial effect of adopting the further scheme is that: the displacement deformation of the unsaturated soil foundation is favorably observed.
Drawings
FIG. 1 is a schematic structural diagram of an experimental apparatus according to the present invention;
FIG. 2 is a front view of a transparent mold box of the present invention;
FIG. 3 is a right side view of a transparent mold box of the present invention;
FIG. 4 is a top view of a transparent mold box of the present invention;
FIG. 5 is a schematic structural diagram of a limiting plate according to the present invention;
FIG. 6 is a schematic view of the structure of the drain pipe of the present invention;
FIG. 7 is a schematic view of the exhaust pipe according to the present invention.
In the drawings, the components represented by the respective reference numerals are listed below:
1. a transparent mold box; 2. a pile body; 3. a base; 4. a counter-force beam; 5. a main jack; 6. an axial force sensor; 7. a dial indicator; 8. an ambient pressure sensor; 9. a strain gauge; 10. a soil pressure cell; 11. a pore pressure sensor; 12. a drain valve; 13. a drain pipe; 14. an exhaust valve; 15. an exhaust pipe; 16. a computer; 17. a light source; 18. a CCD camera; 19. a soil body prestressed plate; 20. a limiting plate; 21. a reaction frame; 23. a loading transfer plate; 24. a secondary jack; 26. a data acquisition box; 27. constant temperature and humidity case.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
Examples
As shown in fig. 1 to 7, the present embodiment provides an experimental apparatus for observing and measuring pile-soil interaction of unsaturated soil, which is characterized by comprising: the device comprises a pile body 2, a loading device, a transparent model box 1, a sensing system for monitoring the stress condition of the pile body 2 and a PIV observation system.
The transparent model box 1 is internally provided with an unsaturated soil foundation, the pile body 2 is vertically arranged, the lower end of the pile body 2 is inserted into the unsaturated soil foundation, the loading device is arranged on the transparent model box 1, the output end of the loading device is connected with the upper end of the pile body 2, the input end of the sensing system is arranged on the pile body 2 and in the unsaturated soil foundation, and the shooting end of the PIV observation system faces the transparent model box 1.
The transparent model box 1 is rectangular, and the change condition of the unsaturated soil foundation in the transparent model box 1 can be observed. The unsaturated soil foundation is composed of transparent soil particles and mineral oil pore fluid, and the refractive index of the pore fluid is communicated with that of the transparent soil particles. The transparent soil particles are made of amorphous silica powder or silica gel or fused silica. The mineral oil gap fluid is a mixture of normal alkane solvent and mineral oil, or solid calcium bromide is dissolved in water. The transparent soil particles are dispersed in mineral oil pore fluid by the unsaturated soil foundation, then the unsaturated soil foundation is vacuumized and precipitated by a vacuum pump until the mixed suspension is transparent, and then the unsaturated soil foundation is solidified according to the test requirements. The transparent soil particles can be filled according to a plurality of undyed soil particle layers and transparent or colored soil particle layers with the same gradation which are arranged at intervals.
The loading device is used for applying loads to the pile body 2 and the unsaturated soil foundation so as to simulate the natural stratum change condition, and therefore stress change between the pile body 2 and the unsaturated soil foundation can be observed. The sensing system is used for detecting and transmitting the stress condition on the pile body 2 to display the microscopic stress change, so that the interaction condition of pile and soil can be observed. The PIV observation system is used for shooting the transparent model box 1, so that the shot pictures can be analyzed to judge the deformation condition of the unsaturated soil foundation. The PIV observation system is a Particle Image Velocimetry (PIV for short).
The technical scheme of the embodiment has the advantages that the change of the displacement field of the soil body around the pile body 2 in the soil body deformation process and the shear zone forming development process when the pile body 2 bears the cyclic vertical load or the pile body 2 and the soil body bear the static load and the whole process can be observed in the loading process of the pile body 2, and meanwhile, a series of mechanical parameters under various actions such as the pile side resistance, the pile end resistance, the soil pressure at different positions away from the pile, the pore water pressure, the ambient pressure and the like can be obtained and detected under various actions such as the cyclic load of the pile body 2 or the static load of the pile body 2 and the soil body in the loading process, so that the engineering significance for researching the interaction between the pile body 2 and unsaturated soil is achieved.
Preferably, in this embodiment, the loading device includes a frame body, a main jack 5 for applying a load to the pile body 2, and a sub jack 24 for applying a load to the unsaturated soil foundation, the frame body is erected on the transparent model box 1, the main jack 5 and the sub jack 24 are both connected to the frame body, an output end of the main jack 5 is connected to the pile body 2, and an output end of the sub jack 24 is connected to the unsaturated soil foundation.
Wherein, the support body is used for supporting main jack 5 and secondary jack 24 for main jack 5 can exert to pile body 2, and secondary jack 24 can exert the load to unsaturated soil base. Wherein, main jack 5 and inferior jack 24 all vertical setting, and the output of the two all faces vertical below, does benefit to and applies the load. Wherein the main jack 5 and the secondary jack 24 are driven by servo motors.
Preferably, in this embodiment, the output end of the main jack 5 is fixedly provided with an loading transfer plate 23, and the upper end of the pile body 2 is fixedly connected with the loading transfer plate 23. The loading transfer plate 23 is beneficial to being connected with the pile body 2, so that the pile body 2 is better driven to move, and the load is applied to the pile body 2. Wherein pile body 2 can be a plurality of, and the upper end of a plurality of pile bodies 2 all is connected with loading transfer plate 23 to a plurality of pile bodies 2 pass through a main jack 5 drive, can observe a plurality of pile bodies 2 and the interact with the unsaturated soil foundation. Wherein the loading transfer plate 23 is horizontally disposed.
Preferably, in this embodiment, a soil prestress plate 19 for covering the unsaturated soil foundation is arranged in the transparent model box 1, and the output end of the secondary jack 24 extends into the transparent model box 1 and is connected with the soil prestress plate 19. The soil body prestressed plate 19 is horizontally arranged at the top end of the unsaturated soil foundation, and when the secondary jack 24 drives the soil body prestressed plate 19 to move, the unsaturated soil foundation is pressed downwards, so that the unsaturated soil foundation is loaded. The unsaturated soil foundation can be uniformly loaded through the arranged soil body prestressed plates 19, and the effect is better. The soil body prestressed plate 19 is arranged to preload the unsaturated soil foundation to simulate the stress state of the soil body and control the loading process of the pile body 2. The soil body prestressed plate 19 is provided with a circular hole for the pile body 2 to pass through, and the diameter of the circular hole is consistent with the size of the pile body 2.
Preferably, in this embodiment, the frame body includes a base 3, a reaction frame 21 and a reaction beam 4, the transparent model box 1 is connected to the base 3, the bottom end of the reaction frame 21 is connected to the base 3, the reaction beam 4 is connected to the top end of the reaction frame 21, the reaction beam 4 is located vertically above the transparent model box 1, and the primary jack 5 and the secondary jack 24 are both connected to the reaction beam 4.
Wherein, reaction frame 21 includes two stands and box fixed beam, and box fixed beam fixed connection is on the base, the vertical setting of two stands, the lower extreme and the 3 fixed connection of base of two stands, the upper end of stand is equipped with the circular trompil that a plurality of triangles were arranged, and reaction beam 4 passes through the screw and is connected in the stand upper end with the cooperation of circular trompil. Wherein the middle part of the counter-force beam 4 is provided with a fixed opening for installing the main jack 5 and the secondary jack 24. Wherein, the heights of the two upright posts are higher than the height of the transparent model box 1.
Preferably, still be equipped with between two stands and be used for the spacing limiting plate 20 of pile body 2, the both ends and two stands of limiting plate 20 pass through screwed connection, are equipped with a plurality of spacing holes on the limiting plate 20, a plurality of spacing holes and a plurality of pile body 2 one-to-one, and the lower extreme of a plurality of pile bodies 2 passes the spacing hole that corresponds and inserts in the unsaturated soil foundation.
Preferably, in this embodiment, the sensing system includes an axial force sensor 6, a dial indicator 7 and a plurality of strain gauges 9, the axial force sensor 6 is connected to the top end of the main jack 5, the axial force sensor 6 detects the applied force of the main jack 5, two ends of the dial indicator 7 are respectively connected to the reaction beam 4 and the loading transmission plate 23, the dial indicator 7 detects the displacement distance of the loading transmission plate 23, and the plurality of strain gauges 9 are connected to the pile body 2 at equal intervals along the length direction of the pile body 2.
The purpose of the axial force sensor 6 is to record the specific value of the applied force, provide process reference for the soil driving process and the cyclic loading and provide convenience for subsequent processing. The cyclic loading process refers to dynamic load change simulated through the cyclic process after the static load of the pile body 2 foundation is stable. The dial indicator 7 can record the displacement distance of the loading transfer plate 23, so that the pile body 2 is driven to be driven into the unsaturated soil foundation. The plurality of strain gauges 9 are used for detecting a change in stress received by the pile body 2 in the unsaturated soil foundation when a load is applied.
Preferably, in this embodiment, the transparent model box 1 includes a transparent box body and a steel plate, the top end of the transparent box body is open, the steel plate is located in the transparent box body and is fixedly connected with the inner wall on one side, and the steel plate is provided with a plurality of soil pressure boxes 10 and a plurality of pore pressure sensors 11. The transparent box body is used for filling unsaturated soil foundation. The transparent box body can observe the condition of the unsaturated soil foundation inside. The transparent box body is made of organic glass. Wherein the size of the transparent box body is 800mm multiplied by 400mm multiplied by 800 mm. Wherein the steel sheet is used for supporting a plurality of soil pressure cell 10 and a plurality of pore pressure sensor 11, and wherein a plurality of soil pressure cell 10 and a plurality of pore pressure sensor 11 are from last to down according to 100mm, 150mm and 100mm interval distribution. The plurality of soil pressure cells 10 and the plurality of pore pressure sensors 11 are alternately arranged. The plurality of soil pressure sensors and the plurality of pore pressure sensors 11 are arranged in a laterally equidistant manner. Therefore, the stress and pressure change in the unsaturated soil foundation can be effectively detected.
Preferably, in this embodiment, an exhaust pipe 15 for exhausting and a drain pipe 13 for draining are arranged on a side wall of the bottom end of the transparent box body, one end of the exhaust pipe 15 is communicated with the inside of the transparent box body, one end of the drain pipe 13 is communicated with the inside of the transparent box body, an exhaust valve 14 for opening or closing the exhaust pipe 15 is arranged on the exhaust pipe 15, and a drain valve 12 for opening or closing the drain pipe 13 is arranged on the drain pipe 13. The process of exhaust and drainage can be simulated through the arranged exhaust pipe 15 and the arranged drain pipe 13, so that a real use environment is simulated. Wherein, the drain pipe 13 is a transparent organic glass pipe with scales, and the exhaust pipe 15 is a organic glass pipe with scales and a sealing buoy. The exhaust valve 14 and the drain valve 12 are two-way solenoid valves made of ABS material, and can be controlled by an electric signal to simulate the control of different boundary exhaust and drain conditions.
Wherein, the scale precision of the drain pipe 13 is 0.1ml, and the precision of the exhaust pipe 15 is 0.1 ml. The full opening and closing response time of the discharge valve 14 and the discharge valve 12 is less than 0.1 s.
Preferably, in this embodiment, the inner wall of the transparent box at the side where the drain pipe 13 is provided with an ambient pressure sensor 8 for detecting the ambient pressure of the unsaturated soil foundation. So as to accurately measure the pressure change around the unsaturated soil foundation.
Preferably, in the present embodiment, the transparent mold box 1, the pile body 2 and the loading device are all arranged in the constant temperature and humidity box 27. The test under the constant temperature and humidity state can be guaranteed.
Preferably, in the present embodiment, the PIV observation system includes a light source 17 and a CCD camera 18, the light source 17 and the CCD camera 18 are both located on the front surface of the transparent mold box 1, the light source 17 irradiates light onto the transparent mold box 1, and the CCD camera 18 takes a picture of the transparent mold box 1. The CCD camera 18 can also photograph the scale of the drain pipe 13 and the exhaust pipe 15.
The light source 17 is 50w, and the resolution of the CCD camera 18 is 2000px by 2000 px. The light source 17 illuminates the front face of the transparent model box 1 in order to improve the definition of the unsaturated soil foundation. The CCD camera 18 shoots and collects images of the unsaturated soil foundation in the transparent model box 1, and positioning points with equal intervals are arranged on the periphery of the transparent model box 1 and used for measuring and calculating displacement deformation reference of the unsaturated soil foundation and focusing the camera. Two light sources 17 are provided, and are respectively disposed on both sides of the CCD camera 18.
Preferably, in this embodiment, the soil pressure monitoring system further comprises a computer 16 and a data collector, the computer 16 is used for collecting data, analyzing and processing the data and issuing an instruction according to user settings, the data collector is used for collecting data, the data collector is in electrical signal connection with the computer 16, the data collector is in electrical signal connection with the axial force sensor 6, the dial indicator 7, the ambient pressure sensor 8, the strain gauge 9, the soil pressure cell 10 and the pore pressure sensor 11, and the data collector can collect information. The data collector is also in electrical signal connection with a light source 17 and a CCD camera 18. The computer 16, together with the servo motor, the air release valve 14 and the water release valve 12, is able to control the load applied by the primary jack 5 and the secondary jack 24, as well as control the air release and the water release. The CCD camera 18 can monitor the displacement deformation field of the unsaturated soil foundation in real time and transmit the image to the computer 16 for storage. The computer 16 controls the light source 17, the CCD camera 18 and the loading device, and transmits and feeds back parameters such as time, hydraulic pressure state and the like to the computer 16.
The maximum load of the main jack 5 and the secondary jack 24 is 10T; the servo motors are 2KW and are provided with band-type brakes, and the states of the main jack 5 and the secondary jack 24 can be fixed. The measuring range of the axial force sensor 6 is 100kN, and the precision is 1N. The range of the soil pressure cell 10 is 6MPa, the sensitivity is 0.1KPa, and the precision is 0.1% FS. The range of the pore pressure sensor 11 is 0-35KPa, and the accuracy is 0.1% FS. The working temperature is-20 to +120 ℃. The light source 17 is a 50W rated ac/dc LED floodlight. The CCD camera 18 has a resolution of 2000px by 2000px and an acquisition rate of 240 fps. The side edge of the front surface of the transparent box body is provided with image analysis reference dots at equal intervals for image analysis reference. The dot diameter is 5mm, along the inside wall of high interval 100mm evenly distributed in transparent box, and CCD camera 18 shoots, and image analysis reference dot is as the reference point in the image, conveniently carries out image analysis.
The following brief description of the test process using the device of the present invention takes the transparent soil sample as the unsaturated soil foundation as an example:
step 1: preparing transparent soil sample system
And blending normal alkane solvents or mineral oil according to the refractive index of the used transparent soil particles to obtain a transparent soil solution, and then layering the transparent soil solution according to the unsaturated state required by the test to obtain a transparent soil sample system.
Step 2: system for setting unsaturated transparent soil model
After the water content of the transparent soil sample system is measured, the transparent soil sample system is filled into a transparent box body in layers of 10cm, and each sensor is installed and connected with a computer 16. And paving clay samples on the topmost layer, covering a soil body prestressed plate 19 after filling is finished as required, vertically inserting the pile body 2 into the soil body, and connecting the pile body 2 with a loading device which is fixed on the counter-force beam 4.
And step 3: PIV observation system for installation and debugging
The CCD camera 18 is arranged in front of the transparent box body, the two sides of the CCD camera 18 are respectively provided with the light source 17, the CCD camera 18 is connected with the data acquisition box 26, and the PIV observation system is debugged.
And 4, step 4: installation and debugging
And calibrating each sensor in the transparent box body, debugging the data collection box and ensuring that each system works cooperatively.
And 5: applying load to soil body
And simultaneously turning on all instrument power supplies, the light source 17, the data collection box and the computer 16 for collection and recording, and controlling the secondary jack 24 to apply load to the soil body prestressed plate 19 through the computer 16 so as to deform the soil body, and keeping the state of the secondary jack 24 unchanged until the applied stress reaches the test design requirement and the soil body deforms stably.
Step 6: applying load to pile body 2
Lightly make the pile body 2 contact with the soil body. And starting the PIV observation system and the data collection box to record the initial state. The computer 16 controls the main jack 5 to work, so that the cyclic loading process of loading and unloading step by step or on the basis of a certain loading background is realized. And the displacement process of the soil around the pile body 2 in the loading process of the pile body 2 is monitored in real time through a PIV observation system, and meanwhile, the readings in the drain pipe 13 and the exhaust pipe 15 are shot. The various sensors collect data together, such as pore water pressure in soil, peripheral pressure, lateral pressure of the pile body 2 and other related data changes, and transmit the data to the data acquisition box 26, and the data acquisition box 26 transmits the data to the computer 16 for gathering and processing.
The experimental device can be used for rapidly and continuously observing the deformation shear field of the soil body and measuring the change conditions of the pressure and the pore pressure of the soil body respectively through the CCD camera 18, the soil pressure box 10 and the pore pressure sensor 11, meanwhile, the tracking of soil particles is realized and the change conditions of the displacement shear field and the seepage field of the soil body in the interaction process with the pile body 2 are revealed according to different image gray levels of the soil body with different saturation degrees, the PIV observation system is high in photographing speed and high in photo resolution, and the change rule of the three-dimensional seepage field of unsaturated soil can be observed in real time through the PIV observation system.
In the description of the present invention, it is to be understood that the terms "center", "length", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "inner", "outer", "peripheral side", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. An experimental apparatus for observing and measuring pile-soil interaction of unsaturated soil, comprising: the device comprises a pile body (2), a loading device, a transparent model box (1), a sensing system and a PIV observation system, wherein the sensing system and the PIV observation system are used for monitoring the stress condition of the pile body (2);
be equipped with unsaturated soil foundation in transparent model case (1), pile body (2) vertical setting, the lower extreme of pile body (2) is inserted and is established in the unsaturated soil foundation, loading device installs on transparent model case (1), loading device's output with the upper end of pile body (2) with unsaturated soil foundation connects, sensing system's input is established on pile body (2) with in the unsaturated soil foundation, PIV observation system's shooting end orientation transparent model case (1).
2. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 1, wherein the loading device comprises a frame body, a main jack (5) for applying load to the pile body (2) and a secondary jack (24) for applying load to the unsaturated soil foundation, the frame body is erected on the transparent model box (1), the main jack (5) and the secondary jack (24) are both connected on the frame body, the output end of the main jack (5) is connected with the pile body (2), and the output end of the secondary jack (24) is connected with the unsaturated soil foundation.
3. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 2, wherein the output end of the main jack (5) is fixedly provided with an loading transfer plate (23), and the upper end of the pile body (2) is fixedly connected with the loading transfer plate (23).
4. The experimental facility for observing and measuring pile-soil interaction of unsaturated soil according to claim 3, characterized in that a soil body prestressed plate (19) for covering the unsaturated soil foundation is arranged in the transparent model box (1), and the output end of the secondary jack (24) extends into the transparent model box (1) and is connected with the soil body prestressed plate (19).
5. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 4, wherein the frame body comprises a base (3), a reaction frame (21) and a reaction beam (4), the transparent model box (1) is connected on the base (3), the bottom end of the reaction frame (21) is connected with the base (3), the reaction beam (4) is connected on the top end of the reaction frame (21), the reaction beam (4) is located vertically above the transparent model box (1), and the primary jack (5) and the secondary jack (24) are both connected on the reaction beam (4).
6. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 5, wherein the sensing system comprises an axial force sensor (6), a dial indicator (7) and a plurality of strain gauges (9), the axial force sensor (6) is connected with the top end of the main jack (5), the axial force sensor (6) is used for detecting the applied force of the main jack (5), two ends of the dial indicator (7) are respectively connected with the counter-force beam (4) and the loading transfer plate (23), the displacement distance of the loading transfer plate (23) is detected through the dial indicator (7), and the plurality of strain gauges (9) are connected on the pile body (2) at equal intervals along the length direction of the pile body (2).
7. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 1, wherein the transparent model box (1) comprises a transparent box body and a steel plate, the top end of the transparent box body is open, the steel plate is positioned in the transparent box body and is fixedly connected with the inner wall of one side, and a plurality of soil pressure boxes (10) and a plurality of pore pressure sensors (11) are arranged on the steel plate.
8. The experimental device for observing and measuring pile-soil interaction of unsaturated soil according to claim 7, wherein an exhaust pipe (15) for exhausting and a drain pipe (13) for draining are arranged on the side wall of the bottom end of the transparent box body, one end of the exhaust pipe (15) is communicated with the inside of the transparent box body, one end of the drain pipe (13) is communicated with the inside of the transparent box body, an exhaust valve (14) for opening or closing the exhaust pipe (15) is arranged on the exhaust pipe (15), and a drain valve (12) for opening or closing the drain pipe (13) is arranged on the drain pipe (13).
9. The experimental facility for observing and measuring pile-soil interaction of unsaturated soil according to claim 8, wherein the inner wall of the transparent box body at one side provided with the drain pipe (13) is provided with an ambient pressure sensor (8) for detecting the ambient pressure of the unsaturated soil foundation;
the transparent model box (1), the pile body (2) and the loading device are all arranged in a constant temperature and humidity box (27).
10. The experimental apparatus for observing and measuring the piling interaction of unsaturated soil according to any one of claims 1 to 9, wherein said PIV observing system comprises a light source (17) and a CCD camera (18), said light source (17) and said CCD camera (18) are both located at the front of said transparent mold box (1), said light source (17) irradiates light onto said transparent mold box (1), said CCD camera (18) takes a picture of said transparent mold box (1).
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