In order to improve the reliability of the design and calculation of single piles under the combined vertical and lateral loads, the solutions were presented based on the subgrade reaction method, in which the ultimat...In order to improve the reliability of the design and calculation of single piles under the combined vertical and lateral loads, the solutions were presented based on the subgrade reaction method, in which the ultimate soil resistance was considered and the coefficient of subgrade reaction was assumed to be a constant. The corresponding computational program was developed using FORTRAN language. A comparison between the obtained solutions and the model test results was made to show the validity of the obtained solutions. The calculation results indicate that both the maximum lateral displacement and bending moment increase with the increase of the vertical and lateral loads and the pile length above ground, while decrease as the pile stiffness, the coefficient of subgrade reaction and the yielding displacement of soil increase. It is also shown that the pile head condition controls the pile responses and the vertical load may cause the instability problem to the pile. In general, the proposed method can be employed to calculate the pile responses independent of the magnitude of the pile deflection.展开更多
In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogene...In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones.展开更多
A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement t...A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement to 3D based on a binocular vision model,where two cameras with a well geometrical setting were utilized to image the same object simultaneously.This system utilized two open software packages and some simple programs in MATLAB,which can easily be adjusted to meet user needs at a low cost.The failure planes form an angle with the horizontal line,which are measured at 27°-29°,approximately three-fourths of the frictional angle of soil.The edge of the strain wedge formed in front of the pile is an arc,which is slightly different from the straight line reported in the literature.The active and passive influence zones are about twice and six times of the diameter of the pile,respectively.The test demonstrates the good performance and feasibility of this stereo-PIV system for more advanced geotechnical testing.展开更多
With the high-quality development of urban buildings,higher requirements are come up with for lateral bearing capacity of laterally loaded piles.Consequently,a more accurate analysis to predict the lateral response of...With the high-quality development of urban buildings,higher requirements are come up with for lateral bearing capacity of laterally loaded piles.Consequently,a more accurate analysis to predict the lateral response of the pile within an allowable displacement is an important issue.However,the current p-y curve methods cannot fully take into account the pile-soil interaction,which will lead to a large calculation difference.In this paper,a new analytical p-y curve is established and a finite difference method for determining the lateral response of pile is proposed,which can consider the separation effect of pile-soil interface and the coefficient of circumferential friction resistance.In particular,an analytical expression is developed to determine the compressive soil pressure by dividing the compressive soil pressure into two parts:initial compressive soil pressure and increment of compressive soil pressure.In addition,the relationship between compressive soil pressure and horizontal displacement of the pile is established based on the reasonable assumption.The correctness of the proposed method is verified through four examples.Based on the verified method,a parametric analysis is also conducted to investigate the influences of factors on lateral response of the pile,including internal friction angle,pile length and elastic modulus of pile.展开更多
This paper proposes a Mach Zehnder/Fabry Perot Interferometer(MZI/FPI)fiber sensor based on Single-mode Fiber(SMF)and Hollow-core Fiber(HCF),which has high sensitivity to temperature and lateral loads.The proposed dev...This paper proposes a Mach Zehnder/Fabry Perot Interferometer(MZI/FPI)fiber sensor based on Single-mode Fiber(SMF)and Hollow-core Fiber(HCF),which has high sensitivity to temperature and lateral loads.The proposed device consists of two single-mode fiber cones formed by manually controlling the fusion splicer and an air cavity formed by fusing a section of hollow-core fiber.The structure of the sensor is a double cone cascaded air cavity.At the beginning of the design,we compared the basic transmission spectra of single cone structure and double cone structure experimentally,and therefore chose to use double cone structure and air cavity cascade.Light undergoes its first reflection at the first interface between the single-mode fiber and the air cavity structure,and its second reflection at the second interface between the air cavity structure and the single-mode fiber.The two reflected light waves produced by the two reflections form FP interference,which can be used to measure lateral loads.The transmitted light is excited through the first cone,and a portion of the core mode light is excited to the cladding,while another portion of the core mode light continues to propagate in the core.The light couples at the second cone,and the cladding mode light couples back into the core,forming MZ interference with the core mode light,which can be used to measure temperature.The use of hollow-core fiber to form an air cavity has little effect on transmitted light,while avoiding the problem of crosstalk in dual parameter measurements.By designing temperature and lateral load experiments,this article verifies the sensitivity characteristics of this sensor to temperature and lateral loads.A significant redshift phenomenon was observed in the temperature experiment.A significant redshift phenomenon also occurred in the lateral load experiment.Through wavelength demodulation,the experimental results show that the wavelength sensitivity of the sensor to temperature is 56.29 pm/℃in the range of 30℃to 80℃.The wavelength sensitivity of the sensor to lateral loads is 1.123 nm/N in the range of 0~5 N.In addition,we have prepared multiple sets of fiber optic sensors with this structure and conducted repeated experiments to verify that the sensing performance of this structure of fiber optic sensors for temperature and lateral load is relatively stable.Also,the different waist diameters of cones will have a certain impact on the transmission spectrum of MZ,while the length of the air cavity will also have a certain impact on the reflection spectrum of FP.This article lists some fiber optic sensors for dual parameter measurement of temperature and lateral load.Compared with the listed sensors,the fiber optic sensor proposed in this article has better sensitivity to temperature and lateral load.And the fiber optic sensor proposed in this article has a simple manufacturing process,low production cost,and good performance,which has certain prospects in scientific research and industrial production.展开更多
基金Foundation item： Projects（50708093, 50808159） supported by the National Natural Science Foundation of China
文摘In order to improve the reliability of the design and calculation of single piles under the combined vertical and lateral loads, the solutions were presented based on the subgrade reaction method, in which the ultimate soil resistance was considered and the coefficient of subgrade reaction was assumed to be a constant. The corresponding computational program was developed using FORTRAN language. A comparison between the obtained solutions and the model test results was made to show the validity of the obtained solutions. The calculation results indicate that both the maximum lateral displacement and bending moment increase with the increase of the vertical and lateral loads and the pile length above ground, while decrease as the pile stiffness, the coefficient of subgrade reaction and the yielding displacement of soil increase. It is also shown that the pile head condition controls the pile responses and the vertical load may cause the instability problem to the pile. In general, the proposed method can be employed to calculate the pile responses independent of the magnitude of the pile deflection.
基金Projects(50708093,51208409)supported by the National Natural Science Foundation of ChinaProject(DB01129)supported by the Talent Foundation of Xi’an University of Architecture and Technology,China
文摘In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones.
基金Project(104244) supported by the Natural Sciences and Engineering Research Council of Canada
文摘A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement to 3D based on a binocular vision model,where two cameras with a well geometrical setting were utilized to image the same object simultaneously.This system utilized two open software packages and some simple programs in MATLAB,which can easily be adjusted to meet user needs at a low cost.The failure planes form an angle with the horizontal line,which are measured at 27°-29°,approximately three-fourths of the frictional angle of soil.The edge of the strain wedge formed in front of the pile is an arc,which is slightly different from the straight line reported in the literature.The active and passive influence zones are about twice and six times of the diameter of the pile,respectively.The test demonstrates the good performance and feasibility of this stereo-PIV system for more advanced geotechnical testing.
基金Project(52068004)supported by the National Natural Science Foundation of ChinaProject(2018JJA160134)supported by the Natural Science Foundation of Guangxi Province,ChinaProject(AB19245018)supported by Key Research Projects of Guangxi Province,China。
文摘With the high-quality development of urban buildings,higher requirements are come up with for lateral bearing capacity of laterally loaded piles.Consequently,a more accurate analysis to predict the lateral response of the pile within an allowable displacement is an important issue.However,the current p-y curve methods cannot fully take into account the pile-soil interaction,which will lead to a large calculation difference.In this paper,a new analytical p-y curve is established and a finite difference method for determining the lateral response of pile is proposed,which can consider the separation effect of pile-soil interface and the coefficient of circumferential friction resistance.In particular,an analytical expression is developed to determine the compressive soil pressure by dividing the compressive soil pressure into two parts:initial compressive soil pressure and increment of compressive soil pressure.In addition,the relationship between compressive soil pressure and horizontal displacement of the pile is established based on the reasonable assumption.The correctness of the proposed method is verified through four examples.Based on the verified method,a parametric analysis is also conducted to investigate the influences of factors on lateral response of the pile,including internal friction angle,pile length and elastic modulus of pile.
基金National Natural Science Foundation of China(Nos.6207509,U2001601,61975084)the Jiangsu Provincial Key Research and Development Program(Nos.BE2022079,BE2022055-2)。
文摘This paper proposes a Mach Zehnder/Fabry Perot Interferometer(MZI/FPI)fiber sensor based on Single-mode Fiber(SMF)and Hollow-core Fiber(HCF),which has high sensitivity to temperature and lateral loads.The proposed device consists of two single-mode fiber cones formed by manually controlling the fusion splicer and an air cavity formed by fusing a section of hollow-core fiber.The structure of the sensor is a double cone cascaded air cavity.At the beginning of the design,we compared the basic transmission spectra of single cone structure and double cone structure experimentally,and therefore chose to use double cone structure and air cavity cascade.Light undergoes its first reflection at the first interface between the single-mode fiber and the air cavity structure,and its second reflection at the second interface between the air cavity structure and the single-mode fiber.The two reflected light waves produced by the two reflections form FP interference,which can be used to measure lateral loads.The transmitted light is excited through the first cone,and a portion of the core mode light is excited to the cladding,while another portion of the core mode light continues to propagate in the core.The light couples at the second cone,and the cladding mode light couples back into the core,forming MZ interference with the core mode light,which can be used to measure temperature.The use of hollow-core fiber to form an air cavity has little effect on transmitted light,while avoiding the problem of crosstalk in dual parameter measurements.By designing temperature and lateral load experiments,this article verifies the sensitivity characteristics of this sensor to temperature and lateral loads.A significant redshift phenomenon was observed in the temperature experiment.A significant redshift phenomenon also occurred in the lateral load experiment.Through wavelength demodulation,the experimental results show that the wavelength sensitivity of the sensor to temperature is 56.29 pm/℃in the range of 30℃to 80℃.The wavelength sensitivity of the sensor to lateral loads is 1.123 nm/N in the range of 0~5 N.In addition,we have prepared multiple sets of fiber optic sensors with this structure and conducted repeated experiments to verify that the sensing performance of this structure of fiber optic sensors for temperature and lateral load is relatively stable.Also,the different waist diameters of cones will have a certain impact on the transmission spectrum of MZ,while the length of the air cavity will also have a certain impact on the reflection spectrum of FP.This article lists some fiber optic sensors for dual parameter measurement of temperature and lateral load.Compared with the listed sensors,the fiber optic sensor proposed in this article has better sensitivity to temperature and lateral load.And the fiber optic sensor proposed in this article has a simple manufacturing process,low production cost,and good performance,which has certain prospects in scientific research and industrial production.
