The separation and detection of particles in suspension are essential for a wide spectrum of applications including medical diagnostics.In this field,microfluidic deterministic lateral displacement(DLD)holds a promise...The separation and detection of particles in suspension are essential for a wide spectrum of applications including medical diagnostics.In this field,microfluidic deterministic lateral displacement(DLD)holds a promise due to the ability of continuous separation of particles by size,shape,deformability,and electrical properties with high resolution.DLD is a passive microfluidic separation technique that has been widely implemented for various bioparticle separations from blood cells to exosomes.DLD techniques have been previously reviewed in 2014.Since then,the field has matured as several physics of DLD have been updated,new phenomena have been discovered,and various designs have been presented to achieve a higher separation performance and throughput.Furthermore,some recent progress has shown new clinical applications and ability to use the DLD arrays as a platform for biomolecules detection.This review provides a thorough discussion on the recent progress in DLD with the topics based on the fundamental studies on DLD models and applications for particle separation and detection.Furthermore,current challenges and potential solutions of DLD are also discussed.We believe that a comprehensive understanding on DLD techniques could significantly contribute toward the advancements in the field for various applications.In particular,the rapid,low-cost,and high-throughput particle separation and detection with DLD have a tremendous impact for point-of-care diagnostics.展开更多
The deterministic lateral displacement (DLD) is an important method used to sort particles and cells of different sizes. In this paper, the flexible cell sorting with the DLD method is studied by using a numerical mod...The deterministic lateral displacement (DLD) is an important method used to sort particles and cells of different sizes. In this paper, the flexible cell sorting with the DLD method is studied by using a numerical model based on the immersed boundary-lattice Boltzmann method (IB-LBM). In this model, the fluid motion is solved by the LBM, and the cell membrane-fluid interaction is modeled with the LBM. The proposed model is validated by simulating the rigid particle sorted with the DLD method, and the results are found in good agreement with those measured in experiments. We first study the effect of flexibility on a single cell and multiple cells continuously going through a DLD device. It is found that the cell flexibility can significantly affect the cell path, which means the flexibility could have significant effects on the continuous cell sorting by the DLD method. The sorting characteristics of white blood cells and red blood cells are further studied by varying the spatial distribution of cylinder arrays and the initial cell-cell distance. The numerical results indicate that a well concentrated cell sorting can be obtained under a proper arrangement of cylinder arrays and a large enough initial cell-cell distance.展开更多
This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneury...This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneurysm model was developed,and a self-designed piston pump was used to provide the pulsatile flow conditions.A fluid-structure interaction simulation was applied for comparison with and analysis of experimental findings.The maximum wall displacement oscillation increased as the pulsation frequency and outflow resistance increased,especially at the aneurysm dome.There is an obvious circular motion of the vortex center accompanying the periodic inflow fluctuation,and the pressure at the aneurysm dome at peak flow increased as the pulsatile flow frequency and terminal flow resistance increased.These results could explain why abnormal blood flow with high frequency and high outflow resistance is one of the risk factors for aneurysm rupture.展开更多
The theory of metal plastic deformation is an important part of the strip shape control theories. In order to control the shape and gauge accurately during cold thin strip rolling, the mechanism of the metal lateral f...The theory of metal plastic deformation is an important part of the strip shape control theories. In order to control the shape and gauge accurately during cold thin strip rolling, the mechanism of the metal lateral flow must be revealed clearly. Therefore, the lateral displacement of thin strip was studied by the grid method. Those grids with a line thickness of 10 μm and clear boundaries were successfully manufactured on the strip surface using lithography. Then, the effects of reduction, front and back tension, and taper angle of the first intermediate roll on the metal lateral flow were studied. The strip shape was calculated with and without considering the lateral displacement; furthermore, the calculations were compared with the measured results. The results show that the calculations with considering the lateral displacement are closer to the measured results. In addition, the comparison of finite element analysis results with the experimental results indicates that the test method was reliable.展开更多
Rapid,sensitive,point-of-care detection of pathogenic bacteria is important for food safety.In this study,we developed a novel quantum dot nanobeads-labelled lateral flow immunoassay strip(QBs-labelled LFIAS)combined ...Rapid,sensitive,point-of-care detection of pathogenic bacteria is important for food safety.In this study,we developed a novel quantum dot nanobeads-labelled lateral flow immunoassay strip(QBs-labelled LFIAS)combined with strand displacement loop-mediated isothermal amplification(SD-LAMP)for quantitative Salmonella Typhimurium(ST)detection.Quantum dot nanobeads(QBs)served as fluorescence reporters,providing good detection efficiency.The customizable strand displacement(SD)probe was used in LAMP to improve the specificity of the method and prevent by-product capture.Detection was based on a sandwich immunoassay.A fluorescence strip reader measured the fluorescence intensity(FI)of the test(T)line and control(C)line.The linear detection range of the strip was 10^(2)–10^(8) colony forming units(CFU)·mL^(-1).The visual limit of detection was 10^(3) CFU·mL^(-1),indicating that the system was ten-fold more sensitive than AuNPs-labelled test strips.ST specificity was analyzed in accordance with agarose gel outputs of polymerase chain reaction(PCR)and SD-LAMP.We detected ST in foods with an acceptable recovery of 85%–110%.The method is rapid,simple,almost equipment-free,and suitable for bacterial detection in foods and for clinical diagnosis.展开更多
Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankme...Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.展开更多
Pull-apart basins of three scales were found along the Haiyuan fault zone. The largest one is more than 50km long, named Laolongwan basin developed in Miocene. A model was built to calculate the amount of pull-apart o...Pull-apart basins of three scales were found along the Haiyuan fault zone. The largest one is more than 50km long, named Laolongwan basin developed in Miocene. A model was built to calculate the amount of pull-apart of an extensional basin. Parameters used in calculation include thickness and length of deposition and depth of detachment. The results of calculation show that the amount of pull-apart of the Laolongwan Basin is about 30 km. Based on previous studies and calculating by using the average slip rate method, amount of pull-apart of the other two smaller basins are 22 km and 8 km, respectively. Thus, the total displacement of strike-slip along the Haiyuan fault zone is about 60 km, which is close to the offset of the Yellow River from Jingtai to Jingyuan.展开更多
The method proposed in this paper is based on the fact that the damage in different types of structural members has distinctive influence on the structural stiffness. The intrinsic mechanical property of the structure...The method proposed in this paper is based on the fact that the damage in different types of structural members has distinctive influence on the structural stiffness. The intrinsic mechanical property of the structure is tapped and fully utilized for damage detection. The simplified model of the flexibility of frames treats the individual storeys as springs in series and the frame as an equivalent column. It fully considers the main deformation of all beams and columns in the frame. The deformation property of the simplified model accorded well with that of the actual frame model. The obtained increment of lateral displacement change (IOLDC) at the storey level was found to be very sensitive to the local damage in the frame. A damage detection method is pro- posed using the IOLDCs as the damage identification parameters. Numerical examples demonstrate the potential applicability of this method.展开更多
Due to excessive displacements of tall buildings occasioned by lateral loads, lateral load resisting systems are usually provided to curtail the load effect. The resistance may be offered by Frame Action, Shear Walls,...Due to excessive displacements of tall buildings occasioned by lateral loads, lateral load resisting systems are usually provided to curtail the load effect. The resistance may be offered by Frame Action, Shear Walls, or combined Walls and Frames (also known as Dual System). In this study, finite element based software, ETABS, was used to generate and analyse three-dimensional building models for the assessment of the relative effectiveness of the various lateral load resisting systems. Three models were used, one each for the three resisting systems. Each model consisted of three samples representing three different building heights of 45 m, 75 m, and 99 m. Wind Design Spreadsheet complying with the appropriate British Standards was used to compute preliminary wind load coefficients using the wind speed values from the relevant wind isopleth map of Nigeria as primary data. Lateral wind load was then applied at floor levels of each of the building samples. Each building sample was subjected to three-dimensional analysis for the determination of both the lateral displacements of storey tops and interstorey drifts. The results of the work showed that the dual system was the most efficient lateral-load resisting system based on deflection criterion, as they yielded the least values for lateral displacements and inter-storey drifts. The moment frame was the least stiff of the resisting systems, yielding the highest values of both the lateral displacement and the inter-storey drift.展开更多
When Rankine or Coulomb theories to design of retaining wall are used, it is accepted beforehand that the retaining wall will experience a lateral displacement. This displacement is normally not calculated when a reta...When Rankine or Coulomb theories to design of retaining wall are used, it is accepted beforehand that the retaining wall will experience a lateral displacement. This displacement is normally not calculated when a retaining wall is designed. This paper describes a method to estimate the lateral displacement of retaining walls. A practical example in the lateral displacement of a gravity retaining wall is presented.展开更多
Structures undergoing inelastic displacements during earthquake ground motions are known to sustain some amount of residual displacements, which may make them unusable or unsafe. In this study an attempt is made to es...Structures undergoing inelastic displacements during earthquake ground motions are known to sustain some amount of residual displacements, which may make them unusable or unsafe. In this study an attempt is made to estimate residual displacements for elastic-perfectly-plastic single-degree-of-freedom oscillators with a given lateral strength ratio. It is observed in the case of a class of ground motions that there are no trends in the dependence of residual displacement on the temporal features of the ground motion, and thus any estimation of residual displacements should be carried out only in the statistical sense. Statistical estimation of residual displacement spectrum via normalization with respect to inelastic or elastic spectral displacements is considered, and it is found that normalization with respect to inelastic spectral displacements is preferable. Expressions for residual displacement spectra are proposed for both types of normalizations and for the givenlateral-strength-ratio type oscillators.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
This paper analyzed the deformation mechanism in lateral roof roadway of the Ding Wu-3 roadway which was disturbed by repeated mining of close coal seams Wu-8 and Wu-10 in Pingdingshan No. 1 Mine. To determine the str...This paper analyzed the deformation mechanism in lateral roof roadway of the Ding Wu-3 roadway which was disturbed by repeated mining of close coal seams Wu-8 and Wu-10 in Pingdingshan No. 1 Mine. To determine the strata disturbance scope, the strata displacement angle was used to calculate the protection pillar width. A numerical model was built considering the field geological conditions. In simulation, the mining stress borderline was defined as the contour where the induced stress is 1.5 times of the original stress. Simulation results show the mining stress borderline of the lateral roadway extended 91.7 m outward after repeated mining. Then the original stress increased, deforming the road- way of interest. This deformation agreed with the in situ observations. Moreover, the strata displacement angle changed due to repeated mining. Therefore, reselection of the displacement angle was required to design the protective pillar width. Since a constant strata displacement angle was used in traditional design, the orooosed method was beneficial in field cases.展开更多
A study to estimate land surface movement caused by large surface excavations in sedimentary strata is presented.In stratified or jointed strata the stress relief driven movement adjacent to large excavations can be s...A study to estimate land surface movement caused by large surface excavations in sedimentary strata is presented.In stratified or jointed strata the stress relief driven movement adjacent to large excavations can be significantly larger than expected.High lateral stresses measured in Australia and other places around the world indicate that the ratio of horizontal to vertical stress has been particularly high at shallow depths.The in situ strata is in compression and during excavation,stress is relieved towards the opening causing strata movement.Large excavations such as,open cut mines or highway cuttings,can initiate an extensive horizontal slide of surface layers towards the excavation.These ground movements can be damaging to surface structures such as water storage dams and large buildings.Based on stress measurements at shallow depths in Australian coal mines the study presented here calculates and models the extent of potential ground movement along the bedding surface adjacent to large excavations and provides a new prediction tool of land movement at the excavation boundary that can benefit the geotechnical practitioners in the mining industry.展开更多
This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were appl...This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.展开更多
The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a fro...The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a frontal ramp with displacement gradient, and/or （3） a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts （FTB）. This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral （or oblique） ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.展开更多
In views of the limitations of the existing methods for calculating the pile foundation capacity, a back analysis approach of the m-value is introduced. In order to consider the sensitivity of pile behavior to the m-v...In views of the limitations of the existing methods for calculating the pile foundation capacity, a back analysis approach of the m-value is introduced. In order to consider the sensitivity of pile behavior to the m-value,the relationships between the applied horizontal loads at pile head and the corresponding m-value along with the pile stiffness changes are studied. Based on statistics data from the extensive in-situ tests, the back analysis results suggest an exponential expression for the m-value in various soil conditions and horizontal displacements at pile head. This method is capable of providing an accurate m-value in calculating the pile responses under lateral loads.展开更多
Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,th...Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,the lateral sealing of active faults has rarely been discussed.In this paper,based on the analysis of the composition and structure characteristics of fault fillings,the geological conditions for lateral sealing of active faults and relevant research method were discussed in reference to the lateral sealing mechanisms of inactive fault rocks.It is shown that,in order to satisfy geologically the lateral sealing of active faults,the faults should be antithetic and the faulted strata should be mainly composed of mudstone,so that the displacement pressure of fault fillings is higher than or equal to that of reservoir rocks in oil and gas migration block.Then,a research method for the lateral sealing of active faults was established by comparing the displacement pressure of fillings in the fault with that of reservoir rocks in oil and gas migration block.This method was applied to three antithetic faults(F1,F2 and F3)in No.1 structure of the Nanpu Sag,Bohai Bay Basin.As revealed,the fillings of these three active faults were mostly argillaceous at the stage of natural gas accu-mulation(the late stage of Neogene Minghuazhen Fm sedimentation),and their displacement pressures were higher than that of reservoir rocks in the first member of Paleogene Dongying Fm(F1 and F3)and the Neogene Guantao Fm(F2).Accordingly,they are laterally sealed for natural gas,which is conducive to the accumulation and preservation of natural gas.Industrial gas flow has been produced from the first member of Paleogene Dongying Fm in Well Np101,the Guantao Fm in Well Np1-2 and the first member of Paleogene Dongying Fm in Well Np1,which is in agreement with the analysis result.It is verified that this method is feasible for investigating the lateral sealing of active faults.展开更多
基金the scholarship from NUS Graduate School for integrative science and engineering and funding support from Ministry of Education Academic Research Fund,Singapore(AcRF:R-397-000-270-114,R-397-000-183-112).
文摘The separation and detection of particles in suspension are essential for a wide spectrum of applications including medical diagnostics.In this field,microfluidic deterministic lateral displacement(DLD)holds a promise due to the ability of continuous separation of particles by size,shape,deformability,and electrical properties with high resolution.DLD is a passive microfluidic separation technique that has been widely implemented for various bioparticle separations from blood cells to exosomes.DLD techniques have been previously reviewed in 2014.Since then,the field has matured as several physics of DLD have been updated,new phenomena have been discovered,and various designs have been presented to achieve a higher separation performance and throughput.Furthermore,some recent progress has shown new clinical applications and ability to use the DLD arrays as a platform for biomolecules detection.This review provides a thorough discussion on the recent progress in DLD with the topics based on the fundamental studies on DLD models and applications for particle separation and detection.Furthermore,current challenges and potential solutions of DLD are also discussed.We believe that a comprehensive understanding on DLD techniques could significantly contribute toward the advancements in the field for various applications.In particular,the rapid,low-cost,and high-throughput particle separation and detection with DLD have a tremendous impact for point-of-care diagnostics.
基金supported by the National Natural Science Foundation of China (Grant 81301291)the Beijing Higher Education Young Elite Teacher Project (Grant YETP1208)UNSW Special Research Grants Program
文摘The deterministic lateral displacement (DLD) is an important method used to sort particles and cells of different sizes. In this paper, the flexible cell sorting with the DLD method is studied by using a numerical model based on the immersed boundary-lattice Boltzmann method (IB-LBM). In this model, the fluid motion is solved by the LBM, and the cell membrane-fluid interaction is modeled with the LBM. The proposed model is validated by simulating the rigid particle sorted with the DLD method, and the results are found in good agreement with those measured in experiments. We first study the effect of flexibility on a single cell and multiple cells continuously going through a DLD device. It is found that the cell flexibility can significantly affect the cell path, which means the flexibility could have significant effects on the continuous cell sorting by the DLD method. The sorting characteristics of white blood cells and red blood cells are further studied by varying the spatial distribution of cylinder arrays and the initial cell-cell distance. The numerical results indicate that a well concentrated cell sorting can be obtained under a proper arrangement of cylinder arrays and a large enough initial cell-cell distance.
基金This study was supported by the National Natural Science Foundation of China(Grants 11602053 and 51576033)the Fundamental Research Funds for the Central Universities(Grant DUT18JC23).
文摘This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneurysm model was developed,and a self-designed piston pump was used to provide the pulsatile flow conditions.A fluid-structure interaction simulation was applied for comparison with and analysis of experimental findings.The maximum wall displacement oscillation increased as the pulsation frequency and outflow resistance increased,especially at the aneurysm dome.There is an obvious circular motion of the vortex center accompanying the periodic inflow fluctuation,and the pressure at the aneurysm dome at peak flow increased as the pulsatile flow frequency and terminal flow resistance increased.These results could explain why abnormal blood flow with high frequency and high outflow resistance is one of the risk factors for aneurysm rupture.
基金The authors gratefully acknowledge the support of the National Natural Science Foundation of China （51474190）, Natural Science Foundation of HeBei Province （E2015203311）, and Taiyuan City Science and Technology Major Projects （170203）.
文摘The theory of metal plastic deformation is an important part of the strip shape control theories. In order to control the shape and gauge accurately during cold thin strip rolling, the mechanism of the metal lateral flow must be revealed clearly. Therefore, the lateral displacement of thin strip was studied by the grid method. Those grids with a line thickness of 10 μm and clear boundaries were successfully manufactured on the strip surface using lithography. Then, the effects of reduction, front and back tension, and taper angle of the first intermediate roll on the metal lateral flow were studied. The strip shape was calculated with and without considering the lateral displacement; furthermore, the calculations were compared with the measured results. The results show that the calculations with considering the lateral displacement are closer to the measured results. In addition, the comparison of finite element analysis results with the experimental results indicates that the test method was reliable.
基金This work was supported by the National Key Research and Development Program of China(2019YFC1606300)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01S174)the Guangdong Academy of Sciences Special Project of Implementing Innovation-Driven Development Capacity Building(2018GDASCX-0401).
文摘Rapid,sensitive,point-of-care detection of pathogenic bacteria is important for food safety.In this study,we developed a novel quantum dot nanobeads-labelled lateral flow immunoassay strip(QBs-labelled LFIAS)combined with strand displacement loop-mediated isothermal amplification(SD-LAMP)for quantitative Salmonella Typhimurium(ST)detection.Quantum dot nanobeads(QBs)served as fluorescence reporters,providing good detection efficiency.The customizable strand displacement(SD)probe was used in LAMP to improve the specificity of the method and prevent by-product capture.Detection was based on a sandwich immunoassay.A fluorescence strip reader measured the fluorescence intensity(FI)of the test(T)line and control(C)line.The linear detection range of the strip was 10^(2)–10^(8) colony forming units(CFU)·mL^(-1).The visual limit of detection was 10^(3) CFU·mL^(-1),indicating that the system was ten-fold more sensitive than AuNPs-labelled test strips.ST specificity was analyzed in accordance with agarose gel outputs of polymerase chain reaction(PCR)and SD-LAMP.We detected ST in foods with an acceptable recovery of 85%–110%.The method is rapid,simple,almost equipment-free,and suitable for bacterial detection in foods and for clinical diagnosis.
基金Project(2010G003-F)supported by Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.
文摘Pull-apart basins of three scales were found along the Haiyuan fault zone. The largest one is more than 50km long, named Laolongwan basin developed in Miocene. A model was built to calculate the amount of pull-apart of an extensional basin. Parameters used in calculation include thickness and length of deposition and depth of detachment. The results of calculation show that the amount of pull-apart of the Laolongwan Basin is about 30 km. Based on previous studies and calculating by using the average slip rate method, amount of pull-apart of the other two smaller basins are 22 km and 8 km, respectively. Thus, the total displacement of strike-slip along the Haiyuan fault zone is about 60 km, which is close to the offset of the Yellow River from Jingtai to Jingyuan.
文摘The method proposed in this paper is based on the fact that the damage in different types of structural members has distinctive influence on the structural stiffness. The intrinsic mechanical property of the structure is tapped and fully utilized for damage detection. The simplified model of the flexibility of frames treats the individual storeys as springs in series and the frame as an equivalent column. It fully considers the main deformation of all beams and columns in the frame. The deformation property of the simplified model accorded well with that of the actual frame model. The obtained increment of lateral displacement change (IOLDC) at the storey level was found to be very sensitive to the local damage in the frame. A damage detection method is pro- posed using the IOLDCs as the damage identification parameters. Numerical examples demonstrate the potential applicability of this method.
文摘Due to excessive displacements of tall buildings occasioned by lateral loads, lateral load resisting systems are usually provided to curtail the load effect. The resistance may be offered by Frame Action, Shear Walls, or combined Walls and Frames (also known as Dual System). In this study, finite element based software, ETABS, was used to generate and analyse three-dimensional building models for the assessment of the relative effectiveness of the various lateral load resisting systems. Three models were used, one each for the three resisting systems. Each model consisted of three samples representing three different building heights of 45 m, 75 m, and 99 m. Wind Design Spreadsheet complying with the appropriate British Standards was used to compute preliminary wind load coefficients using the wind speed values from the relevant wind isopleth map of Nigeria as primary data. Lateral wind load was then applied at floor levels of each of the building samples. Each building sample was subjected to three-dimensional analysis for the determination of both the lateral displacements of storey tops and interstorey drifts. The results of the work showed that the dual system was the most efficient lateral-load resisting system based on deflection criterion, as they yielded the least values for lateral displacements and inter-storey drifts. The moment frame was the least stiff of the resisting systems, yielding the highest values of both the lateral displacement and the inter-storey drift.
文摘When Rankine or Coulomb theories to design of retaining wall are used, it is accepted beforehand that the retaining wall will experience a lateral displacement. This displacement is normally not calculated when a retaining wall is designed. This paper describes a method to estimate the lateral displacement of retaining walls. A practical example in the lateral displacement of a gravity retaining wall is presented.
文摘Structures undergoing inelastic displacements during earthquake ground motions are known to sustain some amount of residual displacements, which may make them unusable or unsafe. In this study an attempt is made to estimate residual displacements for elastic-perfectly-plastic single-degree-of-freedom oscillators with a given lateral strength ratio. It is observed in the case of a class of ground motions that there are no trends in the dependence of residual displacement on the temporal features of the ground motion, and thus any estimation of residual displacements should be carried out only in the statistical sense. Statistical estimation of residual displacement spectrum via normalization with respect to inelastic or elastic spectral displacements is considered, and it is found that normalization with respect to inelastic spectral displacements is preferable. Expressions for residual displacement spectra are proposed for both types of normalizations and for the givenlateral-strength-ratio type oscillators.
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Financial supports from the National Natural Science Foundation of China (No. 51204160)the Priority Academic Program Development of Jiangsu Higher Education Institutions of China(No.SZBF2011-6-B35)+1 种基金the National Science and Technology Support Program of China(No.2012BAK04B06)the Project Funded by State Key Laboratory of Coal Resources and Safe Mining of China(No.SKLCRSM11X03)
文摘This paper analyzed the deformation mechanism in lateral roof roadway of the Ding Wu-3 roadway which was disturbed by repeated mining of close coal seams Wu-8 and Wu-10 in Pingdingshan No. 1 Mine. To determine the strata disturbance scope, the strata displacement angle was used to calculate the protection pillar width. A numerical model was built considering the field geological conditions. In simulation, the mining stress borderline was defined as the contour where the induced stress is 1.5 times of the original stress. Simulation results show the mining stress borderline of the lateral roadway extended 91.7 m outward after repeated mining. Then the original stress increased, deforming the road- way of interest. This deformation agreed with the in situ observations. Moreover, the strata displacement angle changed due to repeated mining. Therefore, reselection of the displacement angle was required to design the protective pillar width. Since a constant strata displacement angle was used in traditional design, the orooosed method was beneficial in field cases.
文摘A study to estimate land surface movement caused by large surface excavations in sedimentary strata is presented.In stratified or jointed strata the stress relief driven movement adjacent to large excavations can be significantly larger than expected.High lateral stresses measured in Australia and other places around the world indicate that the ratio of horizontal to vertical stress has been particularly high at shallow depths.The in situ strata is in compression and during excavation,stress is relieved towards the opening causing strata movement.Large excavations such as,open cut mines or highway cuttings,can initiate an extensive horizontal slide of surface layers towards the excavation.These ground movements can be damaging to surface structures such as water storage dams and large buildings.Based on stress measurements at shallow depths in Australian coal mines the study presented here calculates and models the extent of potential ground movement along the bedding surface adjacent to large excavations and provides a new prediction tool of land movement at the excavation boundary that can benefit the geotechnical practitioners in the mining industry.
基金supported by the National Natural Science Foundation of China(Grant Nos.51379118 and 51639002)SDUST Scientific Found(Grant No.2015KYTD104)
文摘This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.
基金supported by MLTM of Korean Government Program 20052004 to S.Kwon
文摘The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a frontal ramp with displacement gradient, and/or （3） a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts （FTB）. This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral （or oblique） ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.
文摘In views of the limitations of the existing methods for calculating the pile foundation capacity, a back analysis approach of the m-value is introduced. In order to consider the sensitivity of pile behavior to the m-value,the relationships between the applied horizontal loads at pile head and the corresponding m-value along with the pile stiffness changes are studied. Based on statistics data from the extensive in-situ tests, the back analysis results suggest an exponential expression for the m-value in various soil conditions and horizontal displacements at pile head. This method is capable of providing an accurate m-value in calculating the pile responses under lateral loads.
基金Project of National Natural Science Foundation of China“Main controlling factors of oil seeping in hydraulic fracturing of fault rock and prediction of tensile fracture pressure”(No:41372154).
文摘Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,the lateral sealing of active faults has rarely been discussed.In this paper,based on the analysis of the composition and structure characteristics of fault fillings,the geological conditions for lateral sealing of active faults and relevant research method were discussed in reference to the lateral sealing mechanisms of inactive fault rocks.It is shown that,in order to satisfy geologically the lateral sealing of active faults,the faults should be antithetic and the faulted strata should be mainly composed of mudstone,so that the displacement pressure of fault fillings is higher than or equal to that of reservoir rocks in oil and gas migration block.Then,a research method for the lateral sealing of active faults was established by comparing the displacement pressure of fillings in the fault with that of reservoir rocks in oil and gas migration block.This method was applied to three antithetic faults(F1,F2 and F3)in No.1 structure of the Nanpu Sag,Bohai Bay Basin.As revealed,the fillings of these three active faults were mostly argillaceous at the stage of natural gas accu-mulation(the late stage of Neogene Minghuazhen Fm sedimentation),and their displacement pressures were higher than that of reservoir rocks in the first member of Paleogene Dongying Fm(F1 and F3)and the Neogene Guantao Fm(F2).Accordingly,they are laterally sealed for natural gas,which is conducive to the accumulation and preservation of natural gas.Industrial gas flow has been produced from the first member of Paleogene Dongying Fm in Well Np101,the Guantao Fm in Well Np1-2 and the first member of Paleogene Dongying Fm in Well Np1,which is in agreement with the analysis result.It is verified that this method is feasible for investigating the lateral sealing of active faults.
