CN109060532B - Karst area ultra-long pile buckling stability indoor model experimental device and method - Google Patents
Karst area ultra-long pile buckling stability indoor model experimental device and method Download PDFInfo
- Publication number
- CN109060532B CN109060532B CN201810854578.1A CN201810854578A CN109060532B CN 109060532 B CN109060532 B CN 109060532B CN 201810854578 A CN201810854578 A CN 201810854578A CN 109060532 B CN109060532 B CN 109060532B
- Authority
- CN
- China
- Prior art keywords
- model
- ultra
- pile
- long pile
- long
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Immunology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Remote Sensing (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The application provides an indoor model experiment device for buckling stability of an ultra-long pile in a karst region, which comprises a soil body model for simulating a lava foundation, an ultra-long pile model locally buried in the soil body model, a loading system connected with the upper end of the ultra-long pile model through a bearing table for providing downward load, and a data acquisition system, wherein the data acquisition system comprises a pressure sensor arranged on the bearing table and used for detecting the load provided by the loading system, a first dial gauge arranged on the loading table and used for measuring settlement, a second dial gauge arranged on the ultra-long pile model and used for measuring horizontal displacement, and a plurality of strain gauges arranged on the surface of the ultra-long pile model and used for measuring deformation data of a pile body, each four strain gauges are connected in a group in a full-bridge group-bridge mode, the output ends of the pressure sensor and each group of the strain gauges are connected with a main control computer, one or more cavities for simulating karst holes are arranged in the soil body model, and the ultra-long pile model passes through one or more cavities.
Description
Technical Field
The application relates to the technical field of buildings, in particular to an indoor model experiment device and method for buckling stability of ultra-long piles in karst areas.
Background
Along with the rapid development of large-scale infrastructure construction, a large number of high-rise buildings and extra-large bridges are pulled out, and the ultra-long piles are widely applied, such as ultra-long steel pipe piles with the length of 83m are adopted in Shanghai Jinmao mansion and world around the world trade centers, and the ultra-long piles are easy to generate buckling damage, buckling stability is valued by vast students, a plurality of students perform theoretical calculation research on the buckling critical load of the ultra-long piles in soft soil areas by using different methods, meanwhile, the students simulate soft soil areas, a plurality of model tests are performed, the accuracy of theoretical calculation is verified, and the buckling stability of the ultra-long piles in soft soil areas is a plurality of breakthrough achievements.
As known from the research results of students on ultra-long piles, the magnitude of the pile surrounding soil resistance of the ultra-long piles is one of the main factors influencing the buckling stability of the piles, the existing research on the ultra-long piles in soft soil areas is carried out, the foundation is continuous in soft soil areas, so that the pile surrounding soil resistance of the ultra-long piles is continuous, however, when the ultra-long piles are positioned in karst areas with karst holes on the foundation, the foundation is discontinuous, so that the pile surrounding soil resistance of the piles is discontinuous, and therefore, the foundation pile buckling stability analysis theory on the traditional ultra-long piles in soft soil areas without karst holes cannot be used for the stability analysis of the ultra-long piles in karst areas.
As the high-rise buildings and large bridges built in karst areas are more and more, the number, the size and the position of karst holes in karst foundations can be known according to the stress of pile foundations, and the pile foundations of the high-rise buildings and large bridges built in karst areas are affected to a certain extent, so that the problem of the buckling stability of the ultra-long piles in the karst areas is not only the requirement of the self development of pile foundation calculation theory, but also the urgent requirement of engineering industry. At present, although students carry out theoretical research on pile buckling problems in karst areas, a theoretical derivation formula is derived according to some basic formulas and empirical formulas, so that a plurality of assumption conditions are given, and the theoretical derivation formula possibly does not accord with the actual conditions of engineering or even has great access.
Disclosure of Invention
In view of this, the embodiment of the application provides an indoor model experiment device and method for buckling stability of ultra-long piles in karst areas, which can compare actual data with theoretical data deduced by formulas, can verify the consistency of the model and actual engineering, can verify the correctness and rationality deduced by theoretical formulas, and lays a foundation for the subsequent theoretical analysis of buckling stability of the ultra-long piles in karst areas.
The embodiment of the application provides an indoor model experiment device for buckling stability of an ultra-long pile in a karst region, which comprises a soil body model for simulating a lava foundation, an ultra-long pile model locally buried in the soil body model, a loading system connected with the upper end of the ultra-long pile model through a bearing table for providing downward load, and a data acquisition system, wherein the data acquisition system comprises a pressure sensor arranged on the bearing table for detecting the load provided by the loading system, a first dial gauge arranged on the loading table for measuring settlement, a second dial gauge arranged on the ultra-long pile model for measuring horizontal displacement and a plurality of strain gauges arranged on the surface of the ultra-long pile model for measuring deformation data of a pile body, each four strain gauges are connected in a group in a full-bridge group-bridge mode, the output ends of the pressure sensor and each group of the strain gauges are connected with a main control machine, one or more cavities for simulating karst holes are arranged in the soil body model, and the ultra-long pile model passes through one or more cavities.
Further, the soil body model is provided with two layers, wherein the upper layer is clay, the lower layer is sand, and the clay duty ratio is larger than the sand duty ratio.
Further, the loading system comprises a flat-plate-shaped bottom frame, a movable column which is arranged on the bottom frame and is vertically upwards, and a reaction frame which is supported by the movable column, wherein a jack is connected with the reaction frame and the loading platform, the loading platform is connected with the corresponding ultra-long pile model through connection, the soil body model is accommodated in a model box, and the model box is positioned on the upper surface of the bottom frame.
Further, the model box is bottomless, the sandy soil is directly supported by the bottom frame, and the lower end of the ultra-long pile model is connected with the bottom frame.
Further, the model box comprises four steel ribs and four organic glass plates, each steel rib is provided with two clamping grooves which are parallel to each other and are perpendicular to each other in the opening direction, the opposite ends of any one of the organic glass plates are clamped in the corresponding clamping grooves of the two steel ribs which are oppositely arranged, at least one of the organic glass plates is provided with a graduated scale which extends along the vertical direction, the two movable columns are arranged, the model box is positioned between the two movable columns, and the lower end area of the model box is provided with a drain hole.
Further, the ultra-long pile model comprises an embedded section embedded into the soil body model and an exposed section exposed out of the soil body model, the second dial indicator is arranged on the exposed section, and the bearing table is connected with the exposed section.
The embodiment of the application also provides a construction method of the experimental device for the buckling stability indoor model of the ultra-long pile in the karst region, which comprises the following steps,
a1: setting up a loading system and vertically setting an ultra-long pile model, enabling the loading system to be connected with the upper end of the ultra-long pile model through a bearing table, setting a pressure sensor and a first dial indicator for measuring settlement on the loading table, setting a strain gauge for measuring deformation data of a pile body and a second dial indicator for measuring horizontal displacement on the ultra-long pile model, wherein each four strain gauges are connected in a group in a full-bridge group-bridge mode, enabling the output ends of the pressure sensor and each group of strain gauges to be connected with a main control computer, and reading and displaying the load data collected by the pressure sensor and the deformation data measured by the strain gauge through the main control computer;
a2: and slowly filling soil from the lower end of the ultra-long pile model upwards, and sleeving a hollow sleeve on the ultra-long pile model when the soil is filled to the height of the required simulated karst cave, so that the sleeve is vertically placed on the soil, and continuously filling the soil until a complete soil model with the simulated karst cave is formed.
Further, the soil body model is provided with two layers, the upper layer is clay, the lower layer is sand, the clay is positioned in the middle and upper parts of the soil body model, the sand is positioned in the lower part of the soil body model, before filling the soil body, the grain composition and the water content of the clay are set according to test requirements, the sand meeting the test porosity requirement is selected, and before the test is started, the complete soil body basic physical and mechanical indexes are obtained through a geotechnical test.
The embodiment of the application also provides an experimental method for the indoor model of the buckling stability of the ultra-long pile in the karst region, which comprises the following steps of,
b1: applying pile top vertical loads to the ultra-long pile model step by using the loading system;
b2: detecting the load through the pressure sensor, respectively measuring the settlement and horizontal displacement of the pile top by using the first dial indicator and the second dial indicator, and measuring the deformation data of the pile body of the ultra-long pile model by using the strain gauge;
b3: and when the sinking amount of the ultra-long pile model under the action of a certain level of load is smaller than 0.1mm/h, the level is considered to be stable, then the next level of load is applied until the ultra-long pile model is damaged, the test is terminated, and a foundation pile load-displacement curve is drawn to analyze the buckling critical load of the ultra-long pile in the karst region.
Further, the maximum pile top settlement or horizontal displacement is allowed as a test termination standard.
Further, when the pile top settlement amount under a certain level load is 5 times larger than that under a previous level load or the pile top horizontal displacement reaches 0.1 times of the pile diameter, the ultra-long pile model is shown to be destroyed.
The technical scheme provided by the embodiment of the application has the beneficial effects that: the experimental device and the method for the buckling stability indoor model of the ultra-long pile in the karst area can conveniently and effectively simulate buckling deformation of the ultra-long pile in the karst area, and the experimental device has the advantages of common parts, simple assembly, simple method operation and strong adaptability; the experimental method simulates the buckling stress and deformation damage process of the ultra-long pile under the karst foundation, qualitatively analyzes the relation between the buckling critical load of the ultra-long pile and the number, size and position of karst holes in the simulated karst foundation, can verify the consistency of a model and an actual project, can verify the correctness and rationality of theoretical formula deduction, lays a foundation for the subsequent theoretical analysis of the buckling stability of the ultra-long pile in the karst region, and has important theoretical significance and engineering application value.
Drawings
FIG. 1 is a schematic diagram of an experimental device of an indoor model of buckling stability of an ultra-long pile in a karst region;
FIG. 2 is a schematic diagram of an ultra-long pile in a common karst cave-free foundation and an ultra-long pile in a karst cave-free foundation in a soil body under the same condition;
FIG. 3 is a schematic view of pile placement for analyzing buckling critical load and karst foundation karst cave number of an ultra-long pile;
FIG. 4 is a schematic view of pile placement for analyzing buckling critical load and karst foundation karst cave position of an ultra-long pile;
fig. 5 is a schematic view of pile placement for analyzing buckling critical load and karst foundation karst cave size of an ultra-long pile.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be further described with reference to the accompanying drawings.
Referring to fig. 1, an embodiment of the present application provides an indoor model experiment device for buckling stability of an ultra-long pile in a karst region, which includes a soil body model for simulating a lava foundation, an ultra-long pile model 4 locally embedded in the soil body model, a loading system connected to an upper end of the ultra-long pile model 4 through a bearing table 2 to provide downward load, and a data acquisition system.
The loading system comprises a flat plate-shaped bottom frame 11, a movable column 12 which is movably arranged on the bottom frame 11 and vertically upwards, a reaction beam 13 which is supported by the movable column 12, and a reaction frame 14 which is fixed at the lower end of the reaction beam 13.
The number of the movable posts 12 is two, and the distance between the two movable posts 12 is adjusted by adjusting the fixed positions of the two movable posts 12 on the bottom frame 11. The loading system further comprises a jack 15, wherein the jack 15 is vertically arranged, is upwards connected with the reaction frame 14 and downwards connected with the loading platform 2. The loading platform 2 is provided with a pressure sensor 31, and when the jack 15 applies downward load to the loading platform 2, the pressure sensor 31 can detect the load and can transmit the detection result to a main control computer in communication connection with the load. The loading platform 2 is further provided with a plurality of first dial indicators 32, the first dial indicators 32 are used for measuring pile top settlement of the ultra-long pile model 4 connected with the loading platform 2, scales on the first dial indicators 32 can be directly read, and in this embodiment, the first dial indicators 32 are preferably electronic dial indicators, are connected with the main control computer, and can transmit measured data to the main control computer. The plurality of first dial indicators 32 are uniformly arranged on the loading table 2, so that the settlement of the pile top can be measured simultaneously from different positions and orientations, and then the average value is taken, so that the measurement error can be reduced, and the measurement accuracy can be improved.
The loading platform 2 is connected with the corresponding ultra-long pile model 4 through the connection part 21, the jack 15 indirectly applies load on the pile top of the ultra-long pile model 4 through the loading platform 2, and the loading platform 2 is utilized to disperse stress, so that the pile top of the ultra-long pile model 4 can be prevented from being distorted, deformed, even damaged and the like due to stress concentration. The connection ratio 21 can not influence the horizontal displacement of the ultra-long pile model 4 when being stressed, so that the test can simulate the real geological environment more truly.
The soil body model is accommodated in a model box, and the model box is positioned on the upper surface of the bottom frame 11. The model box comprises four steel ribs and four organic glass plates 71, each steel rib is provided with two clamping grooves which are parallel to each other and are perpendicular to each other in the opening direction, the opposite ends of any one of the organic glass plates 71 are clamped in the corresponding clamping grooves of the two steel ribs which are oppositely arranged, at least one organic glass plate 71 is provided with a graduated scale 73 which extends along the vertical direction, the model box is bottomless and topmost, and soil mass models in the model box can be observed through the organic glass plates 71. The model box is located between the two movable columns 12, and the lower end region of the plastic glass plate 71 of the model box is provided with a drain hole 72, and the drain hole 72 is communicated with the inside and the outside of the model box and is used for draining water in the soil body model.
When the soil body model is constructed, the karst foundation structure is firstly required to be researched and studied, and then the soil body with corresponding physical and mechanical indexes is prepared according to the karst foundation structure in the nature. In order to simulate the geological conditions of soft upper soil and hard lower rock-embedded body in karst foundation, the selected soil is two layers, the clay 61 in the Wuhan region is primarily adopted as the upper soil, the clay 61 can be provided with corresponding grain composition, water content and the like according to test requirements, the sand 62 in the Wuhan region is primarily adopted as the lower soil, the sand 62 can be primarily set into three states of loose, medium and dense according to test requirements, and the sand 62 with proper loose degree is selected as the lower soil according to test requirements. The clay 61 is positioned in the middle and upper parts of the soil body model, the sand 62 is positioned in the lower part of the soil body model, and the clay 61 is larger than the sand 62.
The ultra-long pile model 4 comprises an embedded section embedded in the soil body model and an exposed section exposed outside the soil body model, the exposed section is positioned at the upper end of the embedded section, and the bearing table 2 is connected with the exposed section. The exposed section is provided with a plurality of second dial indicators 33, the second dial indicators 33 are used for measuring the pile top horizontal displacement of the ultra-long pile model 4, scales on the second dial indicators 33 can be directly read, and in this embodiment, the second dial indicators 33 are preferably electronic dial indicators, are connected with the main control computer, and can transmit measured data to the main control computer. The second dial indicators 33 are uniformly arranged on the exposed section, so that the horizontal displacement of the pile top can be measured simultaneously from different positions and orientations, and then the average value is taken, so that the measurement error can be reduced, and the measurement accuracy can be improved.
The embedded section is provided with a plurality of strain gages 34, a plurality of strain gages 34 encircle the side wall surface of the embedded section and are uniformly distributed upwards and downwards along the side wall surface, every four strain gages 34 are connected in a group by adopting a full-bridge group bridge mode, and the output end of each group of strain gages 34 is connected with the main control computer. The main control computer is used for reading and displaying the load data acquired by the pressure sensor 31 and the deformation data measured by the strain gauge 34, wherein the deformation data measured by the strain gauge 34 comprise the normal stress, the shear stress and the like of the pile body surface.
Since the mold box has no bottom, the sand 62 is directly supported by the bottom frame 11, and the lower end of the ultra-long pile mold 4 may be connected to the bottom frame 11. One or more cavities 5 for simulating karst cave 51 are arranged in the soil body model, and the ultra-long pile model 4 passes through one or more cavities 5. The ultra-long pile model 4 is made of C30 concrete.
The data acquisition system comprises the pressure sensor 31, the first dial indicator 32, the second dial indicator 33, the strain gauge 34 and the main control computer.
The embodiment of the application provides a construction method of an indoor model experimental device for buckling stability of an ultra-long pile in a karst region, which is used for constructing the indoor model experimental device for buckling stability of the ultra-long pile in the karst region, and comprises the following steps,
a1: setting up a loading system and vertically setting an ultra-long pile model, enabling the loading system to be connected with the upper end of the ultra-long pile model 4 through a bearing table 2, setting a pressure sensor 31 and a first dial indicator 32 for measuring settlement amount on the loading table 2, setting a strain gauge 34 for measuring deformation data of a pile body and a second dial indicator 33 for measuring horizontal displacement on the ultra-long pile model 4, wherein each four strain gauges 34 are connected in a group by adopting a full-bridge group bridge mode, enabling the output ends of the pressure sensor 31 and each group of strain gauges 34 to be connected with a main control computer, and reading and displaying load data collected by the pressure sensor 31 and deformation data measured by the strain gauge 34 through the main control computer.
A2: and slowly filling soil from the lower end of the ultra-long pile model 4 upwards, and sleeving a hollow sleeve 5 on the ultra-long pile model 4 when the soil is filled to the height of the required simulated karst cave 51, so that the sleeve 5 is vertically placed on the soil, and continuously filling the soil until a complete soil model with the simulated karst cave is formed.
Thus, the position of the sleeve 5 in the soil model is the position of the simulated karst cave 51, and the karst cave in the karst foundation is simulated by using the sleeve 5. Before the test starts, the basic physical and mechanical indexes of the complete soil body are obtained through a geotechnical test.
Referring to fig. 2 to 5, the embodiment of the application provides an indoor model experimental method for buckling stability of ultra-long piles in karst regions, which utilizes the indoor model experimental device for buckling stability of ultra-long piles in karst regions to simulate and study the buckling stability of ultra-long piles in karst regions, comprising the following steps,
b1: applying pile top vertical loads to the ultra-long pile model 4 step by using the loading system;
b2: detecting the magnitude of the load through the pressure sensor 31, measuring the settlement and horizontal displacement of the pile top by using the first dial gauge 32 and the second dial gauge 33, and measuring the deformation data of the pile body of the ultra-long pile model 4 by using the strain gauge 34;
b3: and when the sinking amount of the ultra-long pile model under the action of a certain level of load is smaller than 0.1mm/h, the level is considered to be stable, then the next level of load is applied until the ultra-long pile model 4 is damaged, the test is terminated, and a foundation pile load-displacement curve is drawn to analyze the buckling critical load of the ultra-long pile in the karst region.
And taking the allowable maximum pile top settlement amount or horizontal displacement as a test termination standard, and indicating that the ultra-long pile model 4 is destroyed when the pile top settlement amount under a certain level load is 5 times greater than the pile top settlement amount under a previous level load or the pile top horizontal displacement reaches 0.1 times of the pile diameter.
In the embodiment, 10 ultra-long pile models are adopted for simulation and research, then the difference of the buckling critical load of the ultra-long piles in the common non-karst cave foundation and the buckling critical load of the ultra-long piles in the karst cave foundation under the same conditions is analyzed, the qualitative relation between the buckling critical load of the ultra-long piles and the karst cave number of the karst cave foundation is analyzed, the qualitative relation between the buckling critical load of the ultra-long piles and the karst cave position of the karst cave foundation is analyzed, and the qualitative relation between the buckling critical load of the ultra-long piles and the karst cave size of the karst cave foundation is analyzed.
Referring to fig. 2, specifically, 10 ultra-long pile models are sequentially numbered from M0 to M9, the ultra-long pile model No. M1 is embedded into a common karst cave-free foundation, the ultra-long pile model No. M2 is embedded into the soil model with a simulated karst cave, and preferably, the soil model with the ultra-long pile model No. M2 has two simulated karst holes arranged up and down. And analyzing the buckling critical load of the ultra-long pile in the common karst cave-free foundation under the same condition by a conventional method, analyzing the buckling critical load of the ultra-long pile in the karst region under the same condition by the karst region buckling stability indoor model experiment method, and comparing to obtain the difference between the buckling critical load of the ultra-long pile in the common karst cave-free foundation and the buckling critical load of the ultra-long pile in the karst cave-free foundation under the same condition.
Referring to fig. 3, the model of the ultra-long pile of the M0 type is embedded into the soil model without the simulated karst cave, the model of the ultra-long pile of the M3 type is embedded into the soil model with one simulated karst cave, the model of the ultra-long pile of the M4 type is embedded into the soil model with two simulated karst cave, and the qualitative relationship between the buckling critical load of the ultra-long pile and the karst foundation karst cave quantity is analyzed by using the experimental method of the buckling stability indoor model of the ultra-long pile of the karst region through the models of the ultra-long piles of the M0 type, the M3 type and the M4 type.
Referring to fig. 4, the ultra-long pile models M5 and M6 are also embedded into the soil model with only one simulated karst cave, but the simulated karst cave positions in the soil model with the ultra-long pile models M3, M5 and M6 are different, and the qualitative relationship between the buckling critical load of the ultra-long pile and the karst foundation karst cave position is analyzed by using the karst region ultra-long pile buckling stability indoor model experimental method through the ultra-long pile models M3, M5 and M6.
Referring to fig. 5, the ultra-long pile models M8 and M9 are also embedded into the soil model with only one simulated karst cave, but the simulated karst cave sizes in the soil model with the ultra-long pile models M5, M8 and M9 are different, and the qualitative relationship between the buckling critical load of the ultra-long pile and the karst foundation karst cave size is analyzed by using the karst region ultra-long pile buckling stability indoor model experimental method through the ultra-long pile models M5, M8 and M9.
The specifications of the ultra-long pile model and the foundation or soil body model corresponding to the ultra-long pile model can be set by referring to the following table:
l refers to pile length, D refers to pile diameter, L refers to pile length buried in soil, n refers to the number of karst cave in foundation, a refers to vertical height of karst cave, D1 refers to distance from upper surface of first karst cave to top end of soil body, D0 refers to vertical distance between adjacent karst cave, and D2 refers to vertical distance from bottom of lowest karst cave to lowest end of soil body.
And obtaining a foundation pile load-displacement curve through a vertical loading test of the soil body model M1-M9, obtaining pile body axial force and side friction resistance distribution rules of the soil body model M1-M9 through actual measurement of pile body strain data, and analyzing and obtaining buckling critical load of the ultra-long piles in the karst area according to the foundation pile load-displacement curve.
The technical scheme provided by the embodiment of the application has the beneficial effects that: the experimental device and the method for the buckling stability indoor model of the ultra-long pile in the karst area can conveniently and effectively simulate buckling deformation of the ultra-long pile in the karst area, and the experimental device has the advantages of common parts, simple assembly, simple method operation and strong adaptability; the experimental method simulates the buckling stress and deformation damage process of the ultra-long pile under the karst foundation, qualitatively analyzes the relation between the buckling critical load of the ultra-long pile and the number, size and position of karst holes in the simulated karst foundation, can verify the consistency of a model and an actual project, can verify the correctness and rationality of theoretical formula deduction, lays a foundation for the subsequent theoretical analysis of the buckling stability of the ultra-long pile in the karst region, and has important theoretical significance and engineering application value.
In this document, terms such as front, rear, upper, lower, etc. are defined with respect to the positions of the components in the drawings and with respect to each other, for clarity and convenience in expressing the technical solution. It should be understood that the use of such orientation terms should not limit the scope of the claimed application.
The embodiments described above and features of the embodiments herein may be combined with each other without conflict.
The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.
Claims (7)
1. An indoor model experiment device for buckling stability of ultra-long piles in karst areas is characterized in that: the system comprises a soil body model for simulating a lava foundation, an ultra-long pile model locally embedded in the soil body model, a loading system connected with the upper end of the ultra-long pile model through a bearing table to provide downward load, and a data acquisition system, wherein the data acquisition system comprises a pressure sensor arranged on the bearing table and used for detecting the load provided by the loading system, a first dial gauge arranged on the bearing table and used for measuring settlement, a second dial gauge arranged on the ultra-long pile model and used for measuring horizontal displacement, and a plurality of strain gauges arranged on the surface of the ultra-long pile model and used for measuring deformation data of a pile body, each four strain gauges are connected in a group in a full-bridge group-bridge mode, the output ends of the pressure sensor and each group of strain gauges are connected with a main control machine, one or more cavities for simulating karst cave are arranged in the soil body model, and the ultra-long pile model passes through one or more cavities;
the soil body model is provided with two layers, wherein the upper layer is clay, the lower layer is sandy soil, and the clay duty ratio is larger than the sandy soil duty ratio;
the loading system comprises a flat-plate-shaped bottom frame, a movable column which is arranged on the bottom frame, a reaction frame which is supported by the movable column, a jack, a bearing table and a soil body model, wherein the movable column is arranged on the bottom frame, the reaction frame is connected with the bearing table, the bearing table is connected with the corresponding ultra-long pile model through a connecting hinge, the soil body model is accommodated in a model box, and the model box is positioned on the upper surface of the bottom frame;
the model box is bottomless, the sandy soil is directly supported by the bottom frame, and the lower end of the ultra-long pile model is connected with the bottom frame;
the ultra-long pile model comprises an embedded section embedded into the soil body model and an exposed section exposed out of the soil body model, the second dial indicator is arranged on the exposed section, and the bearing table is connected with the exposed section.
2. The karst area ultra-long pile buckling stability indoor model experiment device according to claim 1, wherein: the model box comprises four steel ribs and four organic glass plates, each steel rib is provided with two clamping grooves which are parallel to each other and are perpendicular to each other in the opening direction, the opposite ends of any one of the organic glass plates are clamped in the corresponding clamping grooves of the two steel ribs which are oppositely arranged, at least one of the organic glass plates is provided with a graduated scale extending along the vertical direction, the number of the movable columns is two, the model box is located between the two movable columns, and the lower end area of the model box is provided with a drain hole.
3. A construction method of an indoor model experimental device for buckling stability of ultra-long piles in karst areas is characterized by comprising the following steps: an indoor model experiment device for constructing the buckling stability of the ultra-long piles in the karst region according to any one of claims 1 to 2, wherein the construction method comprises the following steps,
a1: setting up a loading system and vertically setting an ultra-long pile model, enabling the loading system to be connected with the upper end of the ultra-long pile model through a bearing table, setting a pressure sensor and a first dial indicator for measuring settlement on the bearing table, setting a strain gauge for measuring deformation data of a pile body and a second dial indicator for measuring horizontal displacement on the ultra-long pile model, wherein each four strain gauges are connected in a group in a full-bridge group-bridge mode, enabling the output ends of the pressure sensor and each group of strain gauges to be connected with a main control computer, and reading and displaying load data acquired by the pressure sensor and deformation data measured by the strain gauge through the main control computer;
a2: and slowly filling soil from the lower end of the ultra-long pile model upwards, and sleeving a hollow sleeve on the ultra-long pile model when the soil is filled to the height of the required simulated karst cave, so that the sleeve is vertically placed on the soil, and continuously filling the soil until a complete soil model with the simulated karst cave is formed.
4. The construction method of the karst area ultra-long pile buckling stability indoor model experimental device is characterized by comprising the following steps: the soil body model has two layers, and the upper strata is clay, and the lower floor is sand, just clay is located the middle part and the upper portion of soil body model, sand is located the lower part of soil body model, before filling the soil body, according to experimental requirement setting granule gradation and the water content of clay to select the sand that accords with experimental looseness requirement, before experimental beginning, obtain complete soil body basic physical mechanical index through geotechnique's experiment.
5. An indoor model experiment method for buckling stability of ultra-long piles in karst areas is characterized by comprising the following steps of: an experimental device for the buckling stability indoor model of an ultra-long pile in a karst region according to any one of claims 1 to 2, comprising the following steps,
b1: applying pile top vertical loads to the ultra-long pile model step by using the loading system;
b2: detecting the load through the pressure sensor, respectively measuring the settlement and horizontal displacement of the pile top by using the first dial indicator and the second dial indicator, and measuring the deformation data of the pile body of the ultra-long pile model by using the strain gauge;
b3: and when the sinking amount of the ultra-long pile model under the action of a certain level of load is smaller than 0.1mm/h, the level is considered to be stable, then the next level of load is applied until the ultra-long pile model is damaged, the test is terminated, and a foundation pile load-displacement curve is drawn to analyze the buckling critical load of the ultra-long pile in the karst region.
6. The karst area ultra-long pile buckling stability indoor model experiment method is characterized by comprising the following steps of: to allow maximum pile top settlement or horizontal displacement as a test termination criterion.
7. The karst area ultra-long pile buckling stability indoor model experiment method is characterized by comprising the following steps of: and when the pile top settlement amount under a certain level of load is 5 times greater than the pile top settlement amount under a previous level of load or the pile top horizontal displacement reaches 0.1 times of the pile diameter, the ultra-long pile model is shown to be destroyed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810854578.1A CN109060532B (en) | 2018-07-30 | 2018-07-30 | Karst area ultra-long pile buckling stability indoor model experimental device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810854578.1A CN109060532B (en) | 2018-07-30 | 2018-07-30 | Karst area ultra-long pile buckling stability indoor model experimental device and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109060532A CN109060532A (en) | 2018-12-21 |
| CN109060532B true CN109060532B (en) | 2023-09-15 |
Family
ID=64831341
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810854578.1A Active CN109060532B (en) | 2018-07-30 | 2018-07-30 | Karst area ultra-long pile buckling stability indoor model experimental device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109060532B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111610094B (en) * | 2020-05-29 | 2021-05-07 | 西南交通大学 | Model test device and test method for high-speed railway roadbed passing karez |
| CN113235675B (en) * | 2021-05-13 | 2024-04-26 | 湖南科技大学 | Indoor model test device for simulating stress deformation of karst cave foundation pile and application method thereof |
| CN113551991B (en) * | 2021-07-05 | 2022-09-06 | 中山大学 | Indoor simulation test device for horizontal loaded pile |
| CN116502315B (en) * | 2023-06-21 | 2023-09-01 | 贵州正业工程技术投资有限公司 | Method and device for calculating bending deformation limit value of steel pipe pile with hinged and pressed inclined struts at two ends |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014088689A (en) * | 2012-10-30 | 2014-05-15 | Ssc Pile Association | Loading test method and loading test device for composite reinforcement ground |
| WO2014106432A1 (en) * | 2013-01-05 | 2014-07-10 | 华南理工大学 | Method for foundation settlement control |
| CN104631519A (en) * | 2015-01-13 | 2015-05-20 | 河海大学 | Pile foundation bearing characteristic model test device and method under complicated load effect |
| CN104790441A (en) * | 2015-04-22 | 2015-07-22 | 杭州科技职业技术学院 | Effective pile length researching simulation test box for variable parameter super-long pile |
| CN105002938A (en) * | 2015-07-29 | 2015-10-28 | 浙江大学 | One-dimensional horizontal circulation load loading device and experiment method thereof |
| CN105571801A (en) * | 2016-01-28 | 2016-05-11 | 中铁十一局集团第五工程有限公司 | Karst pile foundation vibration resistance testing method based on small vibration table model |
| CN106836318A (en) * | 2017-02-28 | 2017-06-13 | 山东大学 | Study the combined type proportional loading experimental rig and method of pile-soil interaction |
| CN107178102A (en) * | 2017-06-28 | 2017-09-19 | 石家庄铁道大学 | Pass through Caves foundation pile ultimate bearing capacity model assay systems and test method |
| CN108166538A (en) * | 2017-12-20 | 2018-06-15 | 河北建设勘察研究院有限公司 | Pass through the ultimate bearing capacity model assay systems and test method of shaped corroded cave model foundation pile model |
| CN208688916U (en) * | 2018-07-30 | 2019-04-02 | 中国地质大学（武汉） | A kind of karst area ultra-long pile buckling stability indoor model experiments device |
-
2018
- 2018-07-30 CN CN201810854578.1A patent/CN109060532B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014088689A (en) * | 2012-10-30 | 2014-05-15 | Ssc Pile Association | Loading test method and loading test device for composite reinforcement ground |
| WO2014106432A1 (en) * | 2013-01-05 | 2014-07-10 | 华南理工大学 | Method for foundation settlement control |
| CN104631519A (en) * | 2015-01-13 | 2015-05-20 | 河海大学 | Pile foundation bearing characteristic model test device and method under complicated load effect |
| CN104790441A (en) * | 2015-04-22 | 2015-07-22 | 杭州科技职业技术学院 | Effective pile length researching simulation test box for variable parameter super-long pile |
| CN105002938A (en) * | 2015-07-29 | 2015-10-28 | 浙江大学 | One-dimensional horizontal circulation load loading device and experiment method thereof |
| CN105571801A (en) * | 2016-01-28 | 2016-05-11 | 中铁十一局集团第五工程有限公司 | Karst pile foundation vibration resistance testing method based on small vibration table model |
| CN106836318A (en) * | 2017-02-28 | 2017-06-13 | 山东大学 | Study the combined type proportional loading experimental rig and method of pile-soil interaction |
| CN107178102A (en) * | 2017-06-28 | 2017-09-19 | 石家庄铁道大学 | Pass through Caves foundation pile ultimate bearing capacity model assay systems and test method |
| CN108166538A (en) * | 2017-12-20 | 2018-06-15 | 河北建设勘察研究院有限公司 | Pass through the ultimate bearing capacity model assay systems and test method of shaped corroded cave model foundation pile model |
| CN208688916U (en) * | 2018-07-30 | 2019-04-02 | 中国地质大学（武汉） | A kind of karst area ultra-long pile buckling stability indoor model experiments device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109060532A (en) | 2018-12-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109060532B (en) | Karst area ultra-long pile buckling stability indoor model experimental device and method | |
| AU2020433233B2 (en) | System and method for monitoring and verifying global failure mode of soil and rock dual-element side slope | |
| CN103882894B (en) | Prestressed concrete pipe pile horizontal bearing characteristic test model and test method | |
| CN204590104U (en) | A kind of bath scaled model experimental device of simulating self-balance testing pile method | |
| CN106049559B (en) | A kind of large diameter pile foundation autobalanced detection method based on load-compensating | |
| CN102607754A (en) | Device for measuring negative skin friction of pile soil | |
| CN202610847U (en) | Measuring device of pile soil negative friction | |
| CN105223080B (en) | Evaluation method for jointed rock performance and bolting and grouting effects under compression-shear condition | |
| CN103195112A (en) | Foundation pile foundation model analyzing method and test device for same | |
| CN111965031A (en) | Tunnel lining and surrounding rock mechanical characteristic test model device and test method | |
| CN108643247A (en) | Soft clay area rectangle foundation pit bottom soil body reinforced model testing device and test method | |
| CN103898930B (en) | Prestressed concrete pipe pile horizontal bearing attribute testing model and modeling method | |
| CN110805076A (en) | Test device and method for simulating reinforcement of passive area of foundation pit | |
| CN205242462U (en) | Research anti -floating pile resists test device that foundation ditch suddenly gushes failure mechanisms | |
| CN206411107U (en) | A kind of lab simulation stress relief method determines the experimental rig of crustal stress | |
| CN211113788U (en) | Simulation device for bulging deformation of long and narrow foundation pit under bias pressure and seepage conditions | |
| Xiao-ling et al. | Model test study on horizontal bearing behavior of pile under existing vertical load | |
| Zhu et al. | Model experimental study of landslides based on combined optical fiber transducer and different types of boreholes | |
| CN110424475B (en) | Simulator for bulging deformation of long and narrow foundation pit under bias and seepage conditions | |
| CN112095682A (en) | Large pile shoe self-elevating platform tread mark research test device and method | |
| CN109403392B (en) | System and method for measuring and calculating horizontal counter force coefficient of soil body | |
| CN106400857A (en) | Model device and method used for field measuring of blockage degree of opening pile interior soil plug | |
| CN215296993U (en) | Multi-connected rock-soil in-situ shear testing device for full-stress path tracking | |
| CN208688916U (en) | A kind of karst area ultra-long pile buckling stability indoor model experiments device | |
| CN106525596B (en) | Lateral bedding counter-force coefficient indoor test device under different stress paths |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |