鉴于传统的位移监测实验模式存在诸多弊端,本文设计了一种基于北斗的高精度位移监测创新试验平台。首先,建立北斗单历元定位数学模型,给出一种适用于北斗多频信号主辅频相关法(MAXCOM)的整周模糊度快速解算流程;然后,基于Visual Studio ...鉴于传统的位移监测实验模式存在诸多弊端,本文设计了一种基于北斗的高精度位移监测创新试验平台。首先,建立北斗单历元定位数学模型,给出一种适用于北斗多频信号主辅频相关法(MAXCOM)的整周模糊度快速解算流程;然后,基于Visual Studio 2019开发平台,运用C#编程语言,研制一种北斗高精度位移监测创新试验平台(LSMS)。试验测试与分析结果表明,LSMS试验平台的北斗位移监测精度可达厘米级,其中北向精度优于0.9 cm,东向精度优于1.2 cm,垂直精度优于3.0 cm,水平精度优于1.5 cm,点位精度优于3.3 cm。本文方法及试验平台用于北斗高精度位移监测创新试验是行之有效的。展开更多
为满足某大型海洋平台模块钢结构焊接的需要,采用SMAW和SAW焊接工艺对S420MLO材料进行焊接试验和力学性能试验。在试验过程中,通过裂纹尖端张开位移(Crack Tip Opening Displacement,CTOD)试验进行焊接工艺评定。试验结果表明,在焊材选...为满足某大型海洋平台模块钢结构焊接的需要,采用SMAW和SAW焊接工艺对S420MLO材料进行焊接试验和力学性能试验。在试验过程中,通过裂纹尖端张开位移(Crack Tip Opening Displacement,CTOD)试验进行焊接工艺评定。试验结果表明,在焊材选用合理、焊接工艺得到严格控制的情况下,通过焊前预热和焊后消氢处理,能获得良好的焊接接头性能,满足相关标准及项目文件的要求,避免对大型钢结构进行焊后热处理。展开更多
A field study on the behavior of three destructive piles in soft soils subjected to axial load was presented.All the three piles with different diameters were base-grouted and installed with strain gauges along the pi...A field study on the behavior of three destructive piles in soft soils subjected to axial load was presented.All the three piles with different diameters were base-grouted and installed with strain gauges along the piles.The complete load transfer behavior of the base-grouted pile was analyzed using measured results.Moreover,the thresholds of the relative pile-soil displacement for fully mobilizing skin frictions in different soils were investigated,and pile tip displacements needed to fully mobilize tip resistances were analyzed.The results of the full-scale loading tests show that the skin frictions are close to the ultimate values when the pile-soil relative displacements are 1%-3% of pile diameter,and the pile tip displacements needed to fully mobilize the tip resistances are about 1.3%-2.0% of pile diameter.The load transmission curve of the soils around the pile tip corresponds to a softening model when the pile is loaded to failure.展开更多
In order to study the settling mechanism of particles in an air-solid magnetically stabilized fluidized bed(MSFB) for separation,we carried out free settling and quasi-zero settling tests on the tracing particles.The ...In order to study the settling mechanism of particles in an air-solid magnetically stabilized fluidized bed(MSFB) for separation,we carried out free settling and quasi-zero settling tests on the tracing particles.The results show that the main resistance forces as the tracing particles settled in an air-solid MSFB were motion resistance force and yield force.The motion resistance and yield forces greatly hindered the free settling of the particles by greatly decreasing the acceleration for settling process of the particles.The acceleration decreased from 3022.62 cm/s 2 to zero in 0.1 s,and in the end,the particles stopped in the air-solid MSFB.The yield force on particles increased with increasing the magnetic field intensity,resulting in decrease of the quasi-zero settling displacement.However,the yield force on particles decreased with increasing the fluidized air velocity,leading to increase of the quasi-zero settling displacement.When the structure and operating parameters of the air-solid MSFB were set up,the yield stress on particles stopped in an air-solid MSFB was a function of diameter and density of particles.The settling displacements of equal diameter particles increased with increasing their densities,and the settling displacements of equal density particles increased with increasing their diameters.展开更多
In order to compensate for the deficiency of present methods of monitoring plane displacement in similarity model tests,such as inadequate real-time monitoring and more manual intervention,an effective monitoring meth...In order to compensate for the deficiency of present methods of monitoring plane displacement in similarity model tests,such as inadequate real-time monitoring and more manual intervention,an effective monitoring method was proposed in this study,and the major steps of the monitoring method include:firstly,time-series images of the similarity model in the test were obtained by a camera,and secondly,measuring points marked as artificial targets were automatically tracked and recognized from time-series images.Finally,the real-time plane displacement field was calculated by the fixed magnification between objects and images under the specific conditions.And then the application device of the method was designed and tested.At the same time,a sub-pixel location method and a distortion error model were used to improve the measuring accuracy.The results indicate that this method may record the entire test,especially the detailed non-uniform deformation and sudden deformation.Compared with traditional methods this method has a number of advantages,such as greater measurement accuracy and reliability,less manual intervention,higher automation,strong practical properties,much more measurement information and so on.展开更多
Soil spatial variability is difficult to evaluate due to insufficient test data.An alternative option is estimation by indirect methods such as inverse analysis.In this paper,two examples are presented to demonstrate ...Soil spatial variability is difficult to evaluate due to insufficient test data.An alternative option is estimation by indirect methods such as inverse analysis.In this paper,two examples are presented to demonstrate the capability and accuracy of the probabilistic estimation method to characterize soil spatial variability with displacement responses.The first example is a soil slope subject to a surcharge load,in which the spatially varied field of the elastic modulus is estimated with displacements.The results show that estimations based on horizontal displacements were more accurate than those based on vertical displacements.The accuracy of the estimated field was substantially reduced by increasing variance of elastic modulus.However,the estimation was generally acceptable as the error was not more than 10%,even for the high variance case(COV^l.5).The accuracy of estimation was also affected by the type of covariance function and the correlation length.When the correlation length decreased,the accuracy of estimation was reduced.The second example is a validation of laboratory model tests where a horizontal load was applied on a layered ground.The estimated thicknesses of soil layers were close to those in the real situation,which demonstrates the capacity of the estimation method.展开更多
To study the deformability and ductility of an innovative precast shear wall joined by bolted connections,experimental tests were conducted on two test walls under monotonic and cyclic loading,respectively;subsequentl...To study the deformability and ductility of an innovative precast shear wall joined by bolted connections,experimental tests were conducted on two test walls under monotonic and cyclic loading,respectively;subsequently,theoretical analysis was performed on the deformation performance of the shear wall assembly.The test results confirmed the favorable deformability and ductility of the specimens.The top displacement of the shear wall assembly was analytically decomposed into several constituent parts,the theoretical formulae of which were subsequently deduced.The compositional analysis demonstrated that the top displacement of the test wall was primarily induced by the elastic deformation of the upper wall panel(UWP),the relative slippages within the bolted connections,and the flexural deformation within the plastic region of the UWP,while the constituent part contributed by the deformation in the connecting steel frame can be neglected.展开更多
文摘为满足某大型海洋平台模块钢结构焊接的需要,采用SMAW和SAW焊接工艺对S420MLO材料进行焊接试验和力学性能试验。在试验过程中,通过裂纹尖端张开位移(Crack Tip Opening Displacement,CTOD)试验进行焊接工艺评定。试验结果表明,在焊材选用合理、焊接工艺得到严格控制的情况下,通过焊前预热和焊后消氢处理,能获得良好的焊接接头性能,满足相关标准及项目文件的要求,避免对大型钢结构进行焊后热处理。
基金Project(51078330) supported by the National Natural Science Foundation of China
文摘A field study on the behavior of three destructive piles in soft soils subjected to axial load was presented.All the three piles with different diameters were base-grouted and installed with strain gauges along the piles.The complete load transfer behavior of the base-grouted pile was analyzed using measured results.Moreover,the thresholds of the relative pile-soil displacement for fully mobilizing skin frictions in different soils were investigated,and pile tip displacements needed to fully mobilize tip resistances were analyzed.The results of the full-scale loading tests show that the skin frictions are close to the ultimate values when the pile-soil relative displacements are 1%-3% of pile diameter,and the pile tip displacements needed to fully mobilize the tip resistances are about 1.3%-2.0% of pile diameter.The load transmission curve of the soils around the pile tip corresponds to a softening model when the pile is loaded to failure.
基金supported by the National Natural Science Foundation of China (Nos. 51134022 and 51174203)the Key Project of Chinese National Programs for Fundamental Research and Development (No. 2012CB214904)+2 种基金the National Natural Science Foundation of China for Innovative Research Group (No. 50921002)the Natural Science Foundation of Jiangsu Province (No. BK2010002)the Fundamental Research Funds for the Central Universities (Nos. 2010QNB11 and 2010ZDP01A06)
文摘In order to study the settling mechanism of particles in an air-solid magnetically stabilized fluidized bed(MSFB) for separation,we carried out free settling and quasi-zero settling tests on the tracing particles.The results show that the main resistance forces as the tracing particles settled in an air-solid MSFB were motion resistance force and yield force.The motion resistance and yield forces greatly hindered the free settling of the particles by greatly decreasing the acceleration for settling process of the particles.The acceleration decreased from 3022.62 cm/s 2 to zero in 0.1 s,and in the end,the particles stopped in the air-solid MSFB.The yield force on particles increased with increasing the magnetic field intensity,resulting in decrease of the quasi-zero settling displacement.However,the yield force on particles decreased with increasing the fluidized air velocity,leading to increase of the quasi-zero settling displacement.When the structure and operating parameters of the air-solid MSFB were set up,the yield stress on particles stopped in an air-solid MSFB was a function of diameter and density of particles.The settling displacements of equal diameter particles increased with increasing their densities,and the settling displacements of equal density particles increased with increasing their diameters.
基金provided by the Program for New Century Excellent Talents in University (No. NCET-06-0477)the Independent Research Project of the State Key Laboratory of Coal Resources and Mine Safety of China University of Mining and Technology (No. SKLCRSM09X01)the Fundamental Research Funds for the Central Universities
文摘In order to compensate for the deficiency of present methods of monitoring plane displacement in similarity model tests,such as inadequate real-time monitoring and more manual intervention,an effective monitoring method was proposed in this study,and the major steps of the monitoring method include:firstly,time-series images of the similarity model in the test were obtained by a camera,and secondly,measuring points marked as artificial targets were automatically tracked and recognized from time-series images.Finally,the real-time plane displacement field was calculated by the fixed magnification between objects and images under the specific conditions.And then the application device of the method was designed and tested.At the same time,a sub-pixel location method and a distortion error model were used to improve the measuring accuracy.The results indicate that this method may record the entire test,especially the detailed non-uniform deformation and sudden deformation.Compared with traditional methods this method has a number of advantages,such as greater measurement accuracy and reliability,less manual intervention,higher automation,strong practical properties,much more measurement information and so on.
基金the National Natural Science Foundation of China(Nos.51979158,51639008,51679135,and 51422905)the Program of Shanghai Academic Research Leader(No.19XD1421900),China。
文摘Soil spatial variability is difficult to evaluate due to insufficient test data.An alternative option is estimation by indirect methods such as inverse analysis.In this paper,two examples are presented to demonstrate the capability and accuracy of the probabilistic estimation method to characterize soil spatial variability with displacement responses.The first example is a soil slope subject to a surcharge load,in which the spatially varied field of the elastic modulus is estimated with displacements.The results show that estimations based on horizontal displacements were more accurate than those based on vertical displacements.The accuracy of the estimated field was substantially reduced by increasing variance of elastic modulus.However,the estimation was generally acceptable as the error was not more than 10%,even for the high variance case(COV^l.5).The accuracy of estimation was also affected by the type of covariance function and the correlation length.When the correlation length decreased,the accuracy of estimation was reduced.The second example is a validation of laboratory model tests where a horizontal load was applied on a layered ground.The estimated thicknesses of soil layers were close to those in the real situation,which demonstrates the capacity of the estimation method.
基金supported by the National Natural Science Foundation of China(Grant No.51078077)
文摘To study the deformability and ductility of an innovative precast shear wall joined by bolted connections,experimental tests were conducted on two test walls under monotonic and cyclic loading,respectively;subsequently,theoretical analysis was performed on the deformation performance of the shear wall assembly.The test results confirmed the favorable deformability and ductility of the specimens.The top displacement of the shear wall assembly was analytically decomposed into several constituent parts,the theoretical formulae of which were subsequently deduced.The compositional analysis demonstrated that the top displacement of the test wall was primarily induced by the elastic deformation of the upper wall panel(UWP),the relative slippages within the bolted connections,and the flexural deformation within the plastic region of the UWP,while the constituent part contributed by the deformation in the connecting steel frame can be neglected.
