Discernment of seismic soil liquefaction is a complex and non-linear procedure that is affected by diversified factors of uncertainties and complexity.The Bayesian belief network(BBN)is an effective tool to present a ...Discernment of seismic soil liquefaction is a complex and non-linear procedure that is affected by diversified factors of uncertainties and complexity.The Bayesian belief network(BBN)is an effective tool to present a suitable framework to handle insights into such uncertainties and cause–effect relationships.The intention of this study is to use a hybrid approach methodology for the development of BBN model based on cone penetration test(CPT)case history records to evaluate seismic soil liquefaction potential.In this hybrid approach,naive model is developed initially only by an interpretive structural modeling(ISM)technique using domain knowledge(DK).Subsequently,some useful information about the naive model are embedded as DK in the K2 algorithm to develop a BBN-K2 and DK model.The results of the BBN models are compared and validated with the available artificial neural network(ANN)and C4.5 decision tree(DT)models and found that the BBN model developed by hybrid approach showed compatible and promising results for liquefaction potential assessment.The BBN model developed by hybrid approach provides a viable tool for geotechnical engineers to assess sites conditions susceptible to seismic soil liquefaction.This study also presents sensitivity analysis of the BBN model based on hybrid approach and the most probable explanation of liquefied sites,owing to know the most likely scenario of the liquefaction phenomenon.展开更多
Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engin...Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engineering. Quiet boundary is adopted on the lateral face while free field boundary is employed at the bottom. Byrne model on dynamic pore water pressure generation is accepted and natural seismic wave EI Centro whose peak acceleration is adjusted to 0.2 g in proportion is used for input. A double-layer foundation with sandy soil in the upper portion while clay soil in the lower part is chosen as the calculation model, which is 30 m in length and 20 m in width. The groundwater level is on the ground surface. Excess pore water pressure rate is considered as a liquefaction index in the three-dimensional non-linear earthquake response computation. The anti-liquefaction effectiveness and its influencing factors, such as confinement element area are studied. For the natural double-layer foundation, it is liquefied when the excess pore water pressure rate reaches 1.0 under the seismic load. Under the same earthquake load, the peak excess pore water pressure reduces to 0.56 after adopting reinforcement of the continuous soil-cement wall, which is 46% lower than before. It indicates that continuous soil-cement wall confinement method can attain the purpose of anti-liquefaction. Accordingly, it can be a sort of engineering measure to carry on the anti-liquefaction foundation treatment.展开更多
This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to ...This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity(VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.展开更多
基金Projects(2016YFE0200100,2018YFC1505300-5.3)supported by the National Key Research&Development Plan of ChinaProject(51639002)supported by the Key Program of National Natural Science Foundation of China
文摘Discernment of seismic soil liquefaction is a complex and non-linear procedure that is affected by diversified factors of uncertainties and complexity.The Bayesian belief network(BBN)is an effective tool to present a suitable framework to handle insights into such uncertainties and cause–effect relationships.The intention of this study is to use a hybrid approach methodology for the development of BBN model based on cone penetration test(CPT)case history records to evaluate seismic soil liquefaction potential.In this hybrid approach,naive model is developed initially only by an interpretive structural modeling(ISM)technique using domain knowledge(DK).Subsequently,some useful information about the naive model are embedded as DK in the K2 algorithm to develop a BBN-K2 and DK model.The results of the BBN models are compared and validated with the available artificial neural network(ANN)and C4.5 decision tree(DT)models and found that the BBN model developed by hybrid approach showed compatible and promising results for liquefaction potential assessment.The BBN model developed by hybrid approach provides a viable tool for geotechnical engineers to assess sites conditions susceptible to seismic soil liquefaction.This study also presents sensitivity analysis of the BBN model based on hybrid approach and the most probable explanation of liquefied sites,owing to know the most likely scenario of the liquefaction phenomenon.
基金Project(50639010, 90815020) supported by the National Natural Science Foundation of ChinaProject(JKCX-200602) supported by South-to-North Water Diversion in Jiangsu Province, China
文摘Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engineering. Quiet boundary is adopted on the lateral face while free field boundary is employed at the bottom. Byrne model on dynamic pore water pressure generation is accepted and natural seismic wave EI Centro whose peak acceleration is adjusted to 0.2 g in proportion is used for input. A double-layer foundation with sandy soil in the upper portion while clay soil in the lower part is chosen as the calculation model, which is 30 m in length and 20 m in width. The groundwater level is on the ground surface. Excess pore water pressure rate is considered as a liquefaction index in the three-dimensional non-linear earthquake response computation. The anti-liquefaction effectiveness and its influencing factors, such as confinement element area are studied. For the natural double-layer foundation, it is liquefied when the excess pore water pressure rate reaches 1.0 under the seismic load. Under the same earthquake load, the peak excess pore water pressure reduces to 0.56 after adopting reinforcement of the continuous soil-cement wall, which is 46% lower than before. It indicates that continuous soil-cement wall confinement method can attain the purpose of anti-liquefaction. Accordingly, it can be a sort of engineering measure to carry on the anti-liquefaction foundation treatment.
基金Project(5141001028)supported by International Cooperation and Exchanges of NSFC,ChinaProjects(51308566,51308565,51409025)supported by the National Natural Science Foundation of ChinaProject(CDJZR12200002)supported by the Fundamental Research Funds for the Central Universities,China
文摘This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity(VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.
文摘砾性土地震液化风险评价是我国工程防震减灾面临的新问题,原位剪切波速试验是具有普适性的技术手段,但现有方法不适用于中国。建立中国模式下基于剪切波速的砾性土液化概率计算新方法,并与已有的基于地震循环剪应力比CSR(cyclic stress ratio)理论建立的CYY(Cao,Youd and Yuan,简称CYY)计算方法进行对比。采用实测数据和不同概率下液化临界线模型的对比分析表明,所提出的中国模式基于剪切波速的砾性土液化概率计算新方法,解决了CYY方法不适用我国的问题,且模型构造较CYY方法先进,克服了CYY方法难以兼顾不同砾性土层埋深和不同地震动强度的缺点。无论是退化为概率0.5的确定性判别结果,还是实测数据下液化概率计算的可靠性,本方法均优于CYY方法。提出的公式已被具有我国样板规范性质的《建筑工程抗震性态设计通则》修订版采纳,可为相关规范修订及工程应用提供指导与技术支持。
