CN113605470A - Test device and test method for simulating slope pile filling-pile foundation model - Google Patents
Test device and test method for simulating slope pile filling-pile foundation model Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 49
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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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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
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Abstract
The invention discloses a simulation slope filling-pile foundation model test device and a test method, and the device comprises a model box, wherein the model box is internally provided with a simulation bedrock, a simulation filling, a lateral pressure loading device and a model foundation pile, the model foundation pile is a hollow cylinder, and the model foundation pile is vertically inserted into the simulation filling and extends into the simulation bedrock; the inner side of the model foundation pile is provided with a plurality of miniature omnidirectional displacement meters, and the outer wall of the model foundation pile is axially provided with n layers of strain gauges; a soil pressure box is also arranged in the simulated filling, and the left side surface and the right side surface of the model box are transparent; the test device is simple in structure and convenient to operate, can effectively simulate the influence of slope accumulation consolidation and lateral sliding on the stress deformation characteristic of the pile foundation, provides a comprehensive and feasible model test device for researching the slope pile filling-pile foundation stress deformation characteristic, and can be used for guiding the design of the pile foundation in the slope accumulation area and providing a design basis.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a test device and a test method for simulating a slope pile filling-pile foundation model.
Background
In the design and construction of highway bridges in mountainous areas, a large number of abandoned parties are usually abandoned on the original slope of a mountain body in a loose filling mode, the filling soil of the abandoned parties is usually in an under-consolidation state due to insufficient compactness, further consolidation and settlement deformation are generated under the influence of environmental factors such as rainfall infiltration, the deformation and stability of the filling soil are seriously influenced, and the forward landslide or potential instability possibly generated by the recent filling soil due to insufficient stability often has great influence on the safety of pile foundations of newly-built road bridges passing through the section.
In the past, research is mostly focused on the negative friction resistance of the pile foundation formed by large-area pile loading, and the analysis on the problem of the negative friction resistance of the pile foundation formed by asymmetric pile loading is less. For a bridge pile foundation, the vertical load borne by the bridge pile foundation is mainly the action of negative friction resistance caused by slope filling, and the filling is asymmetric filling for the pile foundation. And the newly filled and poorly consolidated soil can generate consolidation and settlement effects, so that the pile foundation generates negative friction resistance. Meanwhile, the lateral sliding and extrusion of the slope accumulation have influence on the horizontal deformation of the bridge pile foundation, and the action mechanism and the influence rule of the slope accumulation need to be systematically researched.
The road, bridge and culvert foundation and foundation design specification (JTG D63) and the building pile foundation technical specification (JGJ 94) adopt an effective stress method to calculate the pile side negative frictional resistance. The calculation of the average vertical effective stress of the i-th layer soil on the pile side does not consider the influence of the change of the effective stress after the soil filling consolidation, the original slope of the newly piled and filled soil has influence on the soil consolidation, and the division of the soil layer on the pile side is also influenced by the original slope. Therefore, it is necessary to provide a test apparatus and a method for simulating a slope filling-pile foundation model.
Disclosure of Invention
The invention aims to provide a test device and a test method for simulating a slope pile filling-pile foundation model, aiming at the problems in the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that:
a simulated slope landfill-pile foundation model test device comprises a model box, wherein simulated bedrock is arranged in the model box, the simulated bedrock is arranged in an inclined mode, simulated landfill is arranged above the simulated bedrock, the upper surface of the simulated landfill is horizontal, a reserved space is arranged between the side wall of the simulated landfill along the inclined direction and the inner wall of the model box, and the reserved space is used for placing a lateral pressure loading device; the middle part of the model box is also provided with a model foundation pile, the model foundation pile is a hollow cylinder, the model foundation pile is vertically inserted into the simulation filling soil and extends into the simulation bedrock, and the upper end of the model foundation pile is detachably connected with the model box through a foundation pile fixing component; the inner side of the model foundation pile is inserted with a plurality of miniature omnidirectional displacement meters for measuring the displacement of the model foundation pile, the miniature omnidirectional displacement meters are sequentially connected through a connecting rod, n layers of strain gauges are arranged on the outer wall of the model foundation pile along the axial direction, and the strain gauges are used for measuring the axial force of a pile body of the model foundation pile; a plurality of miniature omnidirectional displacement meters for monitoring the displacement of the soil body are further distributed in the simulated filling, a plurality of soil pressure boxes for monitoring the displacement of the soil body are further distributed in the simulated filling at intervals, and the soil pressure boxes are arranged in a staggered manner with the miniature omnidirectional displacement meters; at least one side of the mold box is made transparent.
The test device is simple in structure and convenient to operate, and by constructing the slope pile filling and foundation pile structural model, the influence of slope deposit consolidation and lateral sliding on the pile foundation stress deformation characteristic can be effectively simulated, a comprehensive and feasible model test device is provided for researching the slope pile filling-pile foundation stress deformation characteristic, and the test device can be used for guiding the design of the pile foundation in the slope pile area and providing a design basis. The model test device can also simulate different base rock surface gradients according to the prototype slope, and research the influence range of the gradients on the filling consolidation and the lateral movement.
The arrangement of the model box provides an environment space for filling bedrock and earth, and pressure can be applied in the space according to needs without being influenced by the external environment, so that the effectiveness of the test is ensured. The simulation bed rock can be set to different slopes according to actual conditions, so that the contact surface of the simulation filling and the simulation bed rock is an inclined plane, and a slope structure is simulated.
The model foundation pile is arranged to simulate the actual foundation pile arrangement situation, and the displacement change and stress strain conditions of the model foundation pile under the action of hand side pressure and top pressure can be obtained in real time by matching the miniature comprehensive displacement meter with the strain gauge. The displacement meter and the soil pressure cell which are arranged in the simulated filling can monitor the change condition of the soil body in real time.
The foundation pile fixing component can well guarantee the position and the verticality of the model foundation pile in the installation and soil filling process, the accuracy of the test is improved, the foundation pile fixing component can release the model foundation pile after the simulated soil filling is finished, the model foundation pile is independently positioned in bedrock and soil, and the measured data are more in line with the actual situation.
The test device also comprises a data analysis system, wherein the data analysis system can acquire and store various monitored test data, and analyze the influences of factors such as soil consolidation, soil horizontal displacement, time and the like on the pile side negative friction resistance and the neutral point position according to the data and the calculation model.
Furthermore, the model box is a rectangular box, the box walls of the model box on two sides in the inclined direction are made of transparent toughened glass, and the side walls of the model box on the other two sides are sealed by steel plates.
The left side and the right side of the model box are provided with transparent toughened glass plates, so that the conditions of displacement and deformation inside the soil body can be directly observed from the outside.
Furthermore, scale marks are further arranged on the side wall and the top wall of the model box, and the included angle between the inclined plane of the simulation bedrock and the horizontal plane is 0-60 degrees.
The setting of scale sign, the confirmation of elevation and position when the basement rock of being convenient for, fill out, foundation pile set up also is favorable to the setting of angle.
Further, the lateral pressure loading device is a hollow rubber model, the bottom surface of the rubber model is tightly abutted to the inclined surface of the simulation bedrock, the top surface of the rubber model is flush with the upper surface of the simulation filling soil, and the section of the rubber model is trapezoidal; the lateral pressure loading device is arranged at the top of the inclined slope.
The lateral pressure loading device can provide horizontal thrust for a slope body, and after a soil body moves horizontally, the lateral pressure loading device can move along with the soil body and always keep contact with the soil body, so that the soil body is uniformly stressed horizontally; the lateral pressure loading device is set as a rubber model, the bottom of the rubber model can be adjusted in angle according to the bed rock slope, and stable and comprehensive lateral pressure can be provided by inflating the rubber model.
Furthermore, 2-4 strain gauges are symmetrically arranged on each measuring section, and the model foundation pile is vertically arranged in the middle of the simulated filling soil. The strain gauge arranged along the periphery is used for measuring the axial force of the pile body.
Furthermore, a miniature omnidirectional displacement meter for monitoring the displacement of the soil body is also fixedly connected through a connecting rod, and the miniature omnidirectional displacement meter is arranged at equal intervals in the vertical direction and the horizontal direction. The soil pressure cells are also arranged at equal intervals in the vertical direction and the horizontal direction. The arrangement mode can be used for monitoring the soil body in a layered and partitioned mode, and the condition of each layer of section can be reflected.
Furthermore, the foundation pile fixing assembly comprises a telescopic diagonal draw bar and a telescopic vertical bar, one end of the diagonal draw bar is movably hinged with the edge of the model box, the other end of the diagonal draw bar is fixedly connected with the pile head of the model foundation pile in a threaded manner, one end of the vertical bar is hinged with the top of the model box, and the other end of the vertical bar is also fixedly connected with the pile head of the model foundation pile in a threaded manner; and a pair of horizontal telescopic rods connected with the side wall of the model box are further arranged on two sides of the pile head of the model foundation pile, and the pile head is clamped by the pair of horizontal telescopic rods.
The diagonal draw bars and the vertical bars are matched with the top of the model box to just form a triangular stress space, so that the model box has better stability; the telescopic arrangement is convenient for the adjustment of all directions of positions, and the angle can be stretched and adjusted according to the position of the pile head; the pair of horizontal telescopic rods can clamp the pile head to keep the pile head stable; after filling is finished, clamping can be released, and the model foundation pile keeps a preset pose unchanged; under the action of stress, the model foundation pile can generate displacement without external restraint.
Furthermore, the simulated filling soil is transparent soil, and the internal displacement of the simulated filling soil is judged and observed by utilizing a particle image velocimetry method. Because the left side and the right side of the model box are made of transparent toughened glass, the internal displacement of the filling soil can be visually judged and observed by adopting transparent soil and PIV (particle image velocimetry) technology.
Further, a test method for simulating a slope pile filling-pile foundation model test device comprises the following steps:
(1) accurately modeling a model box, and filling a simulation bedrock in the model box to a designed pile bottom elevation;
(2) setting a model foundation pile, arranging a plurality of miniature omnidirectional displacement meters in the model foundation pile, and arranging n layers of strain gauges on the outer wall of the model foundation pile along the axial direction;
(3) arranging the model foundation piles, adjusting the pile top positions of the model foundation piles to the design height, fixing pile heads by adopting a foundation pile fixing assembly, and keeping the foundation piles vertical;
(4) continuously filling the simulated bedrock to a design position, compacting by vibration in the filling process, and then trimming the rock surface of the simulated bedrock to a design gradient;
(5) filling the simulated filling soil to a designed position, retaining soil on the front side and the rear side through steel plates respectively, reserving a space at the top of a slope, and placing a side pressure loading device; in the process of filling the simulated filling soil, the connecting rod, the miniature omnidirectional displacement meter and the soil pressure cell are arranged in the simulated filling soil at equal intervals;
(6) after filling, loosening the foundation pile fixing assembly, respectively loading external force on the pile top and the rear side of filled soil, and simulating the pile body stress characteristic of the model foundation pile under the pile top load and the pile rear soil body thrust;
(7) and after the group of tests are finished, model tests under different slopes are continuously carried out, the pressure condition of the filling is simulated on each section in front of the pile and each section behind the pile under the condition of different slopes through contrastive analysis, and the displacement condition of the filling is simulated on each section in front of the pile and each section behind the pile.
The test method can effectively research the rule of influence of the prototype slope on the negative friction resistance of the pile side and the displacement of the pile body, and improves the safety of the pile foundation in the slope filling area.
The test method can realize the breakthroughs of the following points: firstly, researching the influence of the gradient of a prototype on the negative frictional resistance of the pile side; secondly, in the soil consolidation process, the effective stress of the soil changes along with the time, and the result of the test method can amend and standardize a formula for calculating the negative frictional resistance of the pile side by adopting an effective stress method; thirdly, the difference of the negative friction resistance of the front side and the rear side of the pile under the action of the horizontal thrust can be analyzed; and fourthly, researching the influence of the gradient on the horizontal range value of the pile side soil layer i in the specification.
Compared with the prior art, the invention has the beneficial effects that: 1. the test device is simple in structure and convenient to operate, and by constructing the slope pile filling and foundation pile structure model, the influence of the consolidation and lateral sliding of the slope pile on the stress deformation characteristic of the pile foundation can be effectively simulated, so that a comprehensive and feasible model test device is provided for researching the slope pile filling-pile foundation stress deformation characteristic, and the test device can be used for guiding the design of the pile foundation in a slope pile area and providing a design basis; 2. the model test device can also simulate different slope of the bedrock surface according to the prototype slope, and research the influence range of the slope on the filling consolidation and the lateral movement; 3. the foundation pile fixing component can well ensure the position and the verticality of the model foundation pile in the installation and soil filling processes, and is favorable for improving the test accuracy, and the foundation pile fixing component can release the model foundation pile after the simulated soil filling is completed, so that the model foundation pile is independently positioned in bedrock and soil, and the measured data is more in line with the actual situation; 4. the lateral pressure loading device can provide horizontal thrust for a slope body, and after a soil body moves horizontally, the lateral pressure loading device can move along with the soil body and always keep contact with the soil body, so that the soil body is uniformly stressed horizontally; 5. the test method can effectively research the rule of influence of the prototype slope on the negative friction resistance of the pile side and the displacement of the pile body, and improves the safety of the pile foundation in the slope filling area.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a test device for simulating a slope filling-pile foundation model according to the present invention;
in the figure: 1. a model box; 2. simulating bedrock; 3. simulating filling; 4. model foundation piles; 5. a miniature omnidirectional displacement meter; 6. a connecting rod; 7. a soil pressure cell; 8. a lateral pressure loading device; 9. scale marks; 10. a diagonal member; 11. a vertical rod.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The first embodiment is as follows:
as shown in fig. 1, a simulated slope landfill-pile foundation model test device comprises a model box 1, wherein a simulated bedrock 2 is arranged in the model box 1, a rock surface of the simulated bedrock 2 is inclined, a simulated landfill 3 is arranged above the simulated bedrock 2, the upper surface of the simulated landfill 3 is horizontal, a reserved space is arranged between the side wall of the simulated landfill 3 in the inclined direction and the inner wall of the model box 1, and the reserved space is used for placing a lateral pressure loading device 8; the middle part of the model box 1 is also provided with a model foundation pile 4, the model foundation pile 4 is a hollow cylinder, the model foundation pile 4 is vertically arranged in the simulation filling 3 and extends into the simulation bedrock 2, and the upper end of the model foundation pile 4 is exposed out of the simulation filling 3 and is detachably connected with the model box 1 through a foundation pile fixing component; a plurality of miniature omnidirectional displacement meters for measuring the displacement of the model foundation pile are inserted into the inner side of the model foundation pile 4 and are sequentially connected through connecting rods, n layers of strain gauges are arranged on the outer wall of the model foundation pile 4 along the axial direction and are used for measuring the axial force of a pile body of the model foundation pile; a plurality of miniature omnidirectional displacement meters 5 for monitoring the displacement of the soil body are further distributed in the simulated filling 3, a plurality of soil pressure boxes 7 for monitoring the displacement of the soil body are further distributed in the simulated filling 3 at intervals, and the soil pressure boxes 7 are staggered with the miniature omnidirectional displacement meters 5; at least one side of the mold box 1 is made transparent.
The test device is simple in structure and convenient to operate, and by constructing the slope pile filling and foundation pile structural model, the influence of slope deposit consolidation and lateral sliding on the pile foundation stress deformation characteristic can be effectively simulated, a comprehensive and feasible model test device is provided for researching the slope pile filling-pile foundation stress deformation characteristic, and the test device can be used for guiding the design of the pile foundation in the slope pile area and providing a design basis. The model test device can also simulate different base rock surface gradients according to the prototype slope, and research the influence range of the gradients on the filling consolidation and the lateral movement.
The arrangement of the model box 1 provides an environmental space for filling bedrock and earth, and pressure can be applied in the space according to needs without being influenced by external environment, so that the effectiveness of the test is ensured. The simulation bedrock 2 can be set to different slopes according to actual conditions, so that the contact surface of the simulation filling 3 and the simulation bedrock 2 is an inclined surface, and a slope structure is simulated.
The model foundation pile 4 is used for simulating the actual foundation pile setting situation, and the displacement change and stress strain conditions of the model foundation pile under the action of hand side pressure and top pressure can be obtained in real time by matching the miniature comprehensive displacement meter and the strain gauge. The displacement meter and the soil pressure cell which are arranged in the simulated filling can monitor the change condition of the soil body in real time.
The assurance that foundation pile fixed subassembly can be fine at the in-process of installation and fill out soil the position and the straightness that hangs down of model foundation pile 4 are favorable to improving experimental accuracy, moreover foundation pile fixed subassembly is filling out can be let after the simulation is filled out soil model foundation pile 4 makes model foundation pile alone is in the bed rock and the soil body, and the data that record like this accord with actual conditions more.
The test device also comprises a data analysis system, wherein the data analysis system can acquire and store various monitored test data, and analyze the influences of factors such as soil consolidation, soil horizontal displacement, time and the like on the pile side negative friction resistance and the neutral point position according to the data and the calculation model.
Further, the model box 1 is a rectangular box, the box walls of the model box 1 on two sides in the inclined direction are made of transparent toughened glass, and the side walls of the model box 1 on the other two sides are sealed by steel plates.
The left side and the right side of the model box 1 are provided with transparent toughened glass plates, so that the displacement and deformation conditions in the soil body can be directly observed from the outside.
Furthermore, scale marks 9 are further arranged on the side wall and the top wall of the model box 1, and the included angle between the inclined plane of the simulation bedrock 2 and the horizontal plane is 0-60 degrees.
The setting of scale sign 9, the affirmation of elevation and position when the bedrock of being convenient for, fill out soil, foundation pile set up also is favorable to the setting of angle.
Further, the lateral pressure loading device 8 is a hollow rubber model, the bottom surface of the rubber model is tightly abutted to the inclined surface of the simulation bedrock 2, the top surface of the rubber model is flush with the upper surface of the simulation filling 3, and the cross section of the rubber model is trapezoidal; the lateral pressure loading device 8 is arranged on the inclined slope surface close to the top of the slope.
The lateral pressure loading device 8 can provide horizontal thrust for a slope body, and after a soil body moves horizontally, the lateral pressure loading device 8 can move along with the soil body and keep contact with the soil body all the time, so that the soil body is uniformly stressed horizontally; the lateral pressure loading device 8 is set as a rubber model, the bottom of the rubber model can be adjusted in angle according to the slope of bedrock, and stable and comprehensive lateral pressure can be provided by inflating the rubber model.
Furthermore, 2-4 strain gauges are symmetrically arranged on each measuring section, and the model foundation pile 4 is vertically arranged in the middle of the simulated filling 3. The strain gauge arranged along the periphery is used for measuring the axial force of the pile body.
Furthermore, a miniature omnidirectional displacement meter 5 for monitoring the displacement of the soil body is also fixedly connected through a connecting rod 6, and the miniature omnidirectional displacement meter 5 is arranged at equal intervals in the vertical direction and the horizontal direction. The soil pressure boxes 7 are also arranged at equal intervals in the vertical direction and the horizontal direction. The arrangement mode can be used for monitoring the soil body in a layered and partitioned mode, and the condition of each layer of section can be reflected.
Further, the foundation pile fixing assembly comprises a telescopic inclined pull rod 10 and a telescopic vertical rod 11, one end of the inclined pull rod 10 is movably hinged with an edge of the model box 1, the other end of the inclined pull rod is fixedly connected with a pile head of the model foundation pile 4 in a threaded manner, one end of the vertical rod 11 is hinged with the top of the model box 1, and the other end of the vertical rod is fixedly connected with the pile head of the model foundation pile 4 in a threaded manner; and a pair of horizontal telescopic rods connected with the side wall of the model box 1 are further arranged on two sides of the pile head of the model foundation pile 4, and the pile head is clamped by the pair of horizontal telescopic rods.
The diagonal draw bar 10 and the vertical bar 11 are matched with the top of the model box to just form a triangular stress space, so that the model box has better stability; the telescopic arrangement is convenient for the adjustment of all directions of positions, and the angle can be stretched and adjusted according to the position of the pile head; the pair of horizontal telescopic rods can clamp the pile head to keep the pile head stable; after filling is finished, clamping can be released, and the model foundation pile keeps a preset pose unchanged; under the action of stress, the model foundation pile can generate displacement without external restraint.
Further, the simulation filling 3 is transparent soil made of similar materials, and the internal displacement of the simulation filling is judged and observed by a particle image velocimetry method. Because the left side and the right side of the model box are made of transparent toughened glass, the internal displacement of the filling soil can be visually judged and observed by adopting transparent soil and PIV (particle image velocimetry) technology. The simulated bedrock is also a bedrock-like material.
Example two:
this example provides the testing method of the device of the first example.
Referring to fig. 1, a test method for simulating a slope fill-pile foundation model test device includes the following steps:
(1) accurately modeling a model box 1, and filling a simulation bedrock 2 in the model box 1 to a designed pile bottom elevation;
(2) setting a model foundation pile 4, arranging a plurality of miniature omnidirectional displacement meters in the model foundation pile 4, and arranging n layers of strain gauges on the outer wall of the model foundation pile 4 along the axial direction;
(3) arranging the model foundation piles 4, adjusting the pile top positions of the model foundation piles 4 to the design height, fixing pile heads by adopting a foundation pile fixing assembly, and keeping the foundation piles vertical;
(4) continuously filling the simulated bedrock 2 to a design position, compacting by vibration in the filling process, and then trimming the rock surface of the simulated bedrock 2 to a design gradient;
(5) filling the simulated filling 3 to a designed position, retaining soil through steel plates on the front side and the rear side respectively, reserving a space at the slope top of the slope on the right side, and placing a lateral pressure loading device 8; in the process of filling the simulated filling 3, the connecting rod 6, the miniature omnidirectional displacement meter 5 and the soil pressure cell 7 are also arranged in the simulated filling 3 at equal intervals;
(6) after filling, loosening the foundation pile fixing assembly, respectively loading external force on the pile top and/or the rear side of filled soil, and simulating the pile body stress characteristic of the model foundation pile 4 under the pile top load and the soil mass thrust behind the pile;
(7) after one group of tests is finished, model tests under different slopes are carried out continuously (the slopes theta are 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees and 60 degrees), and the pressure situation of filling soil of sections (Q1, Q2 and … Qn) before the pile, sections (H1, H2 and … Hn) after the pile, sections (Q1, Q2 and … Qn) before the pile and sections (H1, H2 and H … Hn) after the pile are analyzed in a comparative way under different slopes. These end face positions are indicated by the reference numerals in fig. 1.
The test method can effectively research the rule of influence of the prototype slope on the negative friction resistance of the pile side and the displacement of the pile body, and improves the safety of the pile foundation in the slope filling area.
The test method can realize the breakthroughs of the following points: firstly, researching the influence of the gradient of a prototype on the negative frictional resistance of the pile side; secondly, in the soil consolidation process, the effective stress of the soil changes along with the time, and the result of the test method can amend and standardize a formula for calculating the negative frictional resistance of the pile side by adopting an effective stress method; thirdly, the difference of the negative friction resistance of the front side and the rear side of the pile under the action of the horizontal thrust can be analyzed; and fourthly, researching the influence of the gradient on the horizontal range value of the pile side soil layer i in the specification.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. A simulated slope landfill-pile foundation model test device is characterized by comprising a model box, wherein a simulated bedrock is arranged in the model box, the simulated bedrock is arranged in an inclined mode, simulated landfill is arranged above the simulated bedrock, the upper surface of the simulated landfill is horizontal, a reserved space is arranged between the side wall of the simulated landfill in the inclined direction and the inner wall of the model box, and the reserved space is used for placing a lateral pressure loading device; the middle part of the model box is also provided with a model foundation pile, the model foundation pile is a hollow cylinder, the model foundation pile is vertically inserted into the simulation filling soil and extends into the simulation bedrock, and the upper end of the model foundation pile is detachably connected with the model box through a foundation pile fixing component; the inner side of the model foundation pile is inserted with a plurality of miniature omnidirectional displacement meters for measuring the displacement of the model foundation pile, the miniature omnidirectional displacement meters are sequentially connected through a connecting rod, n layers of strain gauges are arranged on the outer wall of the model foundation pile along the axial direction, and the strain gauges are used for measuring the axial force of a pile body of the model foundation pile; a plurality of miniature omnidirectional displacement meters for monitoring the displacement of the soil body are further distributed in the simulated filling, a plurality of soil pressure boxes for monitoring the displacement of the soil body are further distributed in the simulated filling at intervals, and the soil pressure boxes are arranged in a staggered manner with the miniature omnidirectional displacement meters; at least one side of the mold box is made transparent.
2. The simulated slope landfill-pile foundation model test device of claim 1, wherein the model box is a rectangular box, the box walls of the model box on two sides in the inclined direction are made of transparent toughened glass, and the side walls of the model box on the other two sides are sealed by steel plates.
3. The simulated slope mound-pile foundation model test device of claim 1, wherein the side wall and the top wall of the model box are further provided with scale marks, and the included angle between the inclined plane of the simulated bedrock and the horizontal plane is 0-60 degrees.
4. The simulated slope mound-pile foundation model test device of claim 1, wherein the lateral pressure loading device is a hollow rubber model, the bottom surface of the rubber model is in close abutment with the inclined surface of the simulated bedrock, the top surface of the rubber model is flush with the upper surface of the simulated mound, and the cross section of the rubber model is trapezoidal; the lateral pressure loading device is arranged at the top of the inclined slope.
5. The simulated slope pile fill-pile foundation model test device of claim 1, wherein 2-4 strain gauges are symmetrically arranged on each measuring section, and the model foundation pile is vertically arranged in the middle of the simulated fill.
6. The simulated slope landfill-pile foundation model test device of claim 1, wherein the miniature omnidirectional displacement meters for monitoring the displacement of the soil body are also fixedly connected through the connecting rods, and are arranged at equal intervals in the vertical direction and the horizontal direction.
7. The simulated slope landfill-pile foundation model test device of claim 1, wherein the foundation pile fixing assembly comprises a telescopic diagonal draw bar and a telescopic vertical bar, one end of the diagonal draw bar is movably hinged with the edge of the model box, the other end of the diagonal draw bar is fixedly connected with the pile head of the model foundation pile in a screwed manner, one end of the vertical bar is hinged with the top of the model box, and the other end of the vertical bar is also fixedly connected with the pile head of the model foundation pile in a screwed manner; and a pair of horizontal telescopic rods connected with the side wall of the model box are further arranged on two sides of the pile head of the model foundation pile, and the pile head is clamped by the pair of horizontal telescopic rods.
8. The simulated slope mound-pile foundation model test device of claim 1, wherein the simulated mound is transparent soil, and the internal displacement of the simulated mound is observed and judged by using a particle image velocimetry method.
9. A test method using the simulated slope fill-pile foundation model test device of claim 1, wherein the test method comprises the following steps:
(1) accurately modeling a model box, and filling a simulation bedrock in the model box to a designed pile bottom elevation;
(2) setting a model foundation pile, arranging a plurality of miniature omnidirectional displacement meters in the model foundation pile, and arranging n layers of strain gauges on the outer wall of the model foundation pile along the axial direction;
(3) arranging the model foundation piles, adjusting the pile top positions of the model foundation piles to the design height, fixing pile heads by adopting a foundation pile fixing assembly, and keeping the foundation piles vertical;
(4) continuously filling the simulated bedrock to a design position, compacting by vibration in the filling process, and then trimming the rock surface of the simulated bedrock to a design gradient;
(5) filling the simulated filling soil to a designed position, retaining soil on the front side and the rear side through steel plates respectively, reserving a space at the top of a slope, and placing a side pressure loading device; in the process of filling the simulated filling soil, the connecting rod, the miniature omnidirectional displacement meter and the soil pressure cell are arranged in the simulated filling soil at equal intervals;
(6) after filling, loosening the foundation pile fixing assembly, respectively loading external force on the pile top and/or the rear side of filled soil, and simulating the pile body stress characteristic of the model foundation pile under the pile top load and the soil body thrust behind the pile;
(7) and after the group of tests are finished, model tests under different slopes are continuously carried out, the pressure condition of the filling is simulated on each section in front of the pile and each section behind the pile under the condition of different slopes through contrastive analysis, and the displacement condition of the filling is simulated on each section in front of the pile and each section behind the pile.
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Application publication date: 20211105 |