Nanoqueous phase liquid(NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface,but the testing of its feasibility under water table ...Nanoqueous phase liquid(NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface,but the testing of its feasibility under water table fluctuation has received insufficient attention.The feature in a column test was tested through two cycles of water table fluctuation.The sandy medium in the column was initially saturated,and each cycle of water table fluctuation consisted of one water table falling and one rising,resulting in a drainage and an imbibition of the medium,respectively.It was found that the difference between the simulated and measured results in the first drainage of the column test was minor.However,with the propagation of the water table fluctuations,the simulation errors increased,and the simulation accuracy was not acceptable except for the first drainage in the two fluctuation cycles.The main reason was proved to be the estimation method of residual saturation used in this simulator.Also,based on the column tests,it was assumed that the resulting residual saturation from an incomplete imbibition process was a constant,with a value equal to that of the residual value resulting from the main imbibition process.The results obtained after modifying NAPL simulator with this assumption were found to be more accurate in the first cycle of water table fluctuation,but this accuracy decreased rapidly in the second one.It is concluded that NAPL simulator is not adequate in the case of LNAPL migration under water table fluctuation in sandy medium,unless a feasible assumption to estimate residual saturation is put forward.展开更多
Soil liquefaction, and the permanent deformations that frequently result from it, have caused significant damage in past earthquakes. The procedures used in contemporary geotechnical earthquake engineering practice ar...Soil liquefaction, and the permanent deformations that frequently result from it, have caused significant damage in past earthquakes. The procedures used in contemporary geotechnical earthquake engineering practice are generally based on simplified procedures for the evaluation of the liquefaction potential. The work describes a framework for performance-based earthquake engineering and its use in the development of a performance-based procedure for liquefaction hazard evaluation. The performance-based procedure will be used to show how consistent application of conventional procedures for evaluation of liquefaction potential can influence performance prediction. Implications for liquefaction-resistant design will also be discussed. The purpose is to summarize current procedures for practical prediction of liquefaction behavior, to describe recent advances in the understanding of liquefaction behavior, and to describe the incorporation of this improved understanding into new solutions for detailed modeling of soil liquefaction, Simplified procedures for evaluation of liquefaction hazards will be reviewed relatively briefly, with more details devoted to emerging knowledge about the mechanics of liquefiable soil behavior, and methods for incorporating those mechanics into improved models for performance prediction. In particular it focuses about the influence on the evaluation of Cyclic Resistance Ratio （CRR） by different in-situ tests （Cone Penetration Test （CPT）. Standard Penetration Test （SPT） and Seismic Dilatometer Marchetti Test （SDMT）） and by different shear waves velocity measurements （Down Hole D-H. Cross Hole C-H, Seismic Dilatometer Marchetti Test SDMT）.展开更多
The liquefaction is a very significant phenomenon in clayey silty soils, silty sands and also sands. The high potential of liquefaction is generally recognized when these types of soils are laid under the hydrostatic ...The liquefaction is a very significant phenomenon in clayey silty soils, silty sands and also sands. The high potential of liquefaction is generally recognized when these types of soils are laid under the hydrostatic water table. Low plasticity silts, silty sands and sands are found as recent alluvial deposits in the western coastal part of Albania, especially in the sandy beaches of Adriatic Sea near Durres City. The aim of this study is to evaluate the soil liquefaction potential in the area of Golem. Ten CPTUs （cone penetration test with pore pressure measurements） are carried out for the site investigation of soils. In this paper, results of the CPTU based liquefaction analysis are presented. The data of two CPTUs （10 in total） are analyzed and factor of safety was found by considering different levels of hazard and ground water. The results of liquefaction potential analysis show that the soils in the area of Golem have a high risk of liquefaction.展开更多
基金Project(41072182)supported by the National Natural Science Foundation of ChinaProject(2010Z1-E101)supported by Science and Technology Program of Guangzhou City,China+1 种基金Project(20100103)supported by Science and Technology Program of Daya Bay,Huizhou City,ChinaProject(2012A030700008)supported by the Science and Technology Planning Program of Guangdong Province,China
文摘Nanoqueous phase liquid(NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface,but the testing of its feasibility under water table fluctuation has received insufficient attention.The feature in a column test was tested through two cycles of water table fluctuation.The sandy medium in the column was initially saturated,and each cycle of water table fluctuation consisted of one water table falling and one rising,resulting in a drainage and an imbibition of the medium,respectively.It was found that the difference between the simulated and measured results in the first drainage of the column test was minor.However,with the propagation of the water table fluctuations,the simulation errors increased,and the simulation accuracy was not acceptable except for the first drainage in the two fluctuation cycles.The main reason was proved to be the estimation method of residual saturation used in this simulator.Also,based on the column tests,it was assumed that the resulting residual saturation from an incomplete imbibition process was a constant,with a value equal to that of the residual value resulting from the main imbibition process.The results obtained after modifying NAPL simulator with this assumption were found to be more accurate in the first cycle of water table fluctuation,but this accuracy decreased rapidly in the second one.It is concluded that NAPL simulator is not adequate in the case of LNAPL migration under water table fluctuation in sandy medium,unless a feasible assumption to estimate residual saturation is put forward.
文摘Soil liquefaction, and the permanent deformations that frequently result from it, have caused significant damage in past earthquakes. The procedures used in contemporary geotechnical earthquake engineering practice are generally based on simplified procedures for the evaluation of the liquefaction potential. The work describes a framework for performance-based earthquake engineering and its use in the development of a performance-based procedure for liquefaction hazard evaluation. The performance-based procedure will be used to show how consistent application of conventional procedures for evaluation of liquefaction potential can influence performance prediction. Implications for liquefaction-resistant design will also be discussed. The purpose is to summarize current procedures for practical prediction of liquefaction behavior, to describe recent advances in the understanding of liquefaction behavior, and to describe the incorporation of this improved understanding into new solutions for detailed modeling of soil liquefaction, Simplified procedures for evaluation of liquefaction hazards will be reviewed relatively briefly, with more details devoted to emerging knowledge about the mechanics of liquefiable soil behavior, and methods for incorporating those mechanics into improved models for performance prediction. In particular it focuses about the influence on the evaluation of Cyclic Resistance Ratio （CRR） by different in-situ tests （Cone Penetration Test （CPT）. Standard Penetration Test （SPT） and Seismic Dilatometer Marchetti Test （SDMT）） and by different shear waves velocity measurements （Down Hole D-H. Cross Hole C-H, Seismic Dilatometer Marchetti Test SDMT）.
文摘The liquefaction is a very significant phenomenon in clayey silty soils, silty sands and also sands. The high potential of liquefaction is generally recognized when these types of soils are laid under the hydrostatic water table. Low plasticity silts, silty sands and sands are found as recent alluvial deposits in the western coastal part of Albania, especially in the sandy beaches of Adriatic Sea near Durres City. The aim of this study is to evaluate the soil liquefaction potential in the area of Golem. Ten CPTUs （cone penetration test with pore pressure measurements） are carried out for the site investigation of soils. In this paper, results of the CPTU based liquefaction analysis are presented. The data of two CPTUs （10 in total） are analyzed and factor of safety was found by considering different levels of hazard and ground water. The results of liquefaction potential analysis show that the soils in the area of Golem have a high risk of liquefaction.
