One of the most devastating effects of earthquakes in the seismic regions is liquefaction. Many research works have been done in this field and at present different methods are available for the liquefaction potential...One of the most devastating effects of earthquakes in the seismic regions is liquefaction. Many research works have been done in this field and at present different methods are available for the liquefaction potential assessment. 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 type of soils are laid under the hydrostatic water table. This paper make an overview of two different methods for the evaluation of liquefaction potential, and a case study is presented. Two methods presented here are the Deterministic Approach proposed by Robertson and Wride (1998), and the Probabilistic Approach proposed by Moss and co-workers. Case study of the liquefaction potential evaluation is done for the Golem area, where geotechnical data from CPTU test were collected. The results of analysis in the Golem area show that liquefaction has medium susceptibly to occur. From the analyses, it is shown that the Probabilistic Approach gives more accurate information about the risk of liquefaction than the Deterministic Approach.展开更多
The interpretation and application of CPT(cone penetration test)results is characterized by considerable variability of data,either in measured or correlated parameters.According to the requirements of Eurocode 7 the ...The interpretation and application of CPT(cone penetration test)results is characterized by considerable variability of data,either in measured or correlated parameters.According to the requirements of Eurocode 7 the existing variability in soil properties has to be taken into account statistically during the determination of the characteristic values of each parameter.This should be done by selecting a cautious estimate of the value affecting the limit state.Obtaining the characteristic values of CPT measurements is not an easy task and on this aspect nor clear neither unified guidelines exist.This paper focuses in several approaches to characterize the cone resistance and the sleeve friction using simple statistical analysis,in order for these parameters to be applicable in design.Similar procedures are then applied to determine the characteristic values of correlated parameters from CPT such as the effective friction angle for sands and the undrained shear strength for clays.The resulting characteristic values of the considered parameters emphasize the fact that the prediction and the interpretation of characteristic values of soil properties is a complicated and biased procedure.展开更多
MICP(Microbially induced calcite precipitation),an environmentally friendly soil improvement technique,has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate thro...MICP(Microbially induced calcite precipitation),an environmentally friendly soil improvement technique,has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate through microbial activity to enhance the engineering properties of geomaterials.In this study,piezocone penetration test(CPTU)is used to evaluate the effectiveness of MICP treatment in calcareous sand.The change of physical properties(relative density D and total unit weight)of MICP treated calcareous sand is investigated by conducting CPTU on the geomaterials prepared in a series of mini calibration chambers(25 cm×50 cm).Results indicate that CPTU(tip stress,sleeve friction,and porewater pressure)measurements can be used to interpret the physical characteristics of calcareous sand treated with MICP under seawater conditions.Additionally,a relationship between CPTU measurements,physical parameters(relative density D,and total unit weight y)of MICP treated calcareous sand is proposed and calibrated.The findings of the research extend the implementation of in-situ testing techniques such as CPTU towards physical property evaluation of bio-treated geomaterials in ocean environment,and demonstrate the potential of scaling up MICP techniques for broader engineeringapplication.展开更多
文摘One of the most devastating effects of earthquakes in the seismic regions is liquefaction. Many research works have been done in this field and at present different methods are available for the liquefaction potential assessment. 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 type of soils are laid under the hydrostatic water table. This paper make an overview of two different methods for the evaluation of liquefaction potential, and a case study is presented. Two methods presented here are the Deterministic Approach proposed by Robertson and Wride (1998), and the Probabilistic Approach proposed by Moss and co-workers. Case study of the liquefaction potential evaluation is done for the Golem area, where geotechnical data from CPTU test were collected. The results of analysis in the Golem area show that liquefaction has medium susceptibly to occur. From the analyses, it is shown that the Probabilistic Approach gives more accurate information about the risk of liquefaction than the Deterministic Approach.
文摘The interpretation and application of CPT(cone penetration test)results is characterized by considerable variability of data,either in measured or correlated parameters.According to the requirements of Eurocode 7 the existing variability in soil properties has to be taken into account statistically during the determination of the characteristic values of each parameter.This should be done by selecting a cautious estimate of the value affecting the limit state.Obtaining the characteristic values of CPT measurements is not an easy task and on this aspect nor clear neither unified guidelines exist.This paper focuses in several approaches to characterize the cone resistance and the sleeve friction using simple statistical analysis,in order for these parameters to be applicable in design.Similar procedures are then applied to determine the characteristic values of correlated parameters from CPT such as the effective friction angle for sands and the undrained shear strength for clays.The resulting characteristic values of the considered parameters emphasize the fact that the prediction and the interpretation of characteristic values of soil properties is a complicated and biased procedure.
基金funded by the Tsinghua Shenzhen International Graduate School Research Startup Funds[item number:01030100009].
文摘MICP(Microbially induced calcite precipitation),an environmentally friendly soil improvement technique,has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate through microbial activity to enhance the engineering properties of geomaterials.In this study,piezocone penetration test(CPTU)is used to evaluate the effectiveness of MICP treatment in calcareous sand.The change of physical properties(relative density D and total unit weight)of MICP treated calcareous sand is investigated by conducting CPTU on the geomaterials prepared in a series of mini calibration chambers(25 cm×50 cm).Results indicate that CPTU(tip stress,sleeve friction,and porewater pressure)measurements can be used to interpret the physical characteristics of calcareous sand treated with MICP under seawater conditions.Additionally,a relationship between CPTU measurements,physical parameters(relative density D,and total unit weight y)of MICP treated calcareous sand is proposed and calibrated.The findings of the research extend the implementation of in-situ testing techniques such as CPTU towards physical property evaluation of bio-treated geomaterials in ocean environment,and demonstrate the potential of scaling up MICP techniques for broader engineeringapplication.
