液化后地面下沉量的估计
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摘要
饱和砂样的室内循环试验表明,对于给定的相对密度,液化后重固结的体积应变随剪应变幅值的增加而增加,并且最后趋于最大体积应变。大量的液化砂层数据分析表明,绝大多数场地饱和砂层下沉的支配因素是最大体积应变。本文提出利用由试验所确定的最大体积应变和标准贯入锤击数间的关系来估计液化后地面下沉量的方法。用所建议的方法估计了13个液化场址的下沉量,所得到的估计值与野外观察的下沉量或地震灾害有较好的吻合。根据该途径所给出的地面下沉量可作为衡量场地可能出现液化的轻重程度,从而决策是否采取抗液化措施。
The cyclic loading test data shows that the post-liquefaction volumetric strain for given the relative density increase with the increasing maximum shear strain in a soil,and finally go to its maximum volumetric strain.By examining a bulk of data from liquefaction sites,the factor controlling the post-liquefaction settlements in sand deposits is the maximum volumetric strain.The methods for estimating the settlements by the relationships between SPT N and maximum volumetric strain after liquefaction are presented in the paper.The proposed methodology is used to estimate the settlements at 13 liquefaction sites.The estimated values of the settlements obtained from these examples can compare favorably with settlements or damage observed at these sites.The estimated settlements given by the procedure may be used as an index to measure liquefaction degree at the site,and then the decision can be made whether or not to adopt anti-liquefaction measure.
The cyclic loading test data shows that the post-liquefaction volumetric strain for given the relative density increase with the increasing maximum shear strain in a soil,and finally go to its maximum volumetric strain.By examining a bulk of data from liquefaction sites,the factor controlling the post-liquefaction settlements in sand deposits is the maximum volumetric strain.The methods for estimating the settlements by the relationships between SPT N and maximum volumetric strain after liquefaction are presented in the paper.The proposed methodology is used to estimate the settlements at 13 liquefaction sites.The estimated values of the settlements obtained from these examples can compare favorably with settlements or damage observed at these sites.The estimated settlements given by the procedure may be used as an index to measure liquefaction degree at the site,and then the decision can be made whether or not to adopt anti-liquefaction measure.
引文
[1]Lee K L,Albasisa A.Earthquake-induced settlements insaturatedsands[J].J.Soil Mech.Found.Div.,ASCE,1974,100(4):387~400
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[3]Tatsuoka F,Sasaki T,Yamada S.Settlement in saturatedsandinduced by cyclic undrained simple shear[A].Proc.,8thWorld Conf.Earthq.Engrg.,San Francisco,Calif.,1984:95~102
[4]Tokimatsu K,Seed HB.Evaluation of settlements in sandsdue to earthquake shaking[J].Journal of GeotechnicalEngineering,1987,113(8)
[5]Ishihara K,Yoshimine M.Evaluation of settlementsinsanddeposits following liquefaction during earthquakes[J].Soilsand Foundations,Japanese Society of Soil Mechanics andFoundation Engineering,1992,32(1)
[6]崔卫国,符圣聪.饱和砂土层的震陷估计[J].工程勘察,1993,(4)Cui Wei-guo,Fu Sheng-cong.Estimation of settlements insaturated sand deposits after earthquake[J].GeotechnicalInvestigation&Surveying,1993,(4)
[7]符圣聪,江静贝.简化的液化判别概率法[J].工程抗震与加固改造,2008,30(3):93~98Fu Sheng-cong,Jiang Jing-bei.A simplified probabilisticmethodfor liquefaction evaluation[J].Earthquake ResistantEngineering and Retrofitting,2008,30(3):93~98
[8]刘恢先.唐山大地震震害(第一册)[M].北京:地震出版社,1985Liu Hui-xian.The Great Tangshan Earthquake of 1976[M].Beijing:Seismic Press,1985
[2]Silver ML,Seed H B.Volume changes in sands duringcyclic loading[J].J.Soil Mech.Found.Div.,ASCE,1971,97(9):1171~1182
[3]Tatsuoka F,Sasaki T,Yamada S.Settlement in saturatedsandinduced by cyclic undrained simple shear[A].Proc.,8thWorld Conf.Earthq.Engrg.,San Francisco,Calif.,1984:95~102
[4]Tokimatsu K,Seed HB.Evaluation of settlements in sandsdue to earthquake shaking[J].Journal of GeotechnicalEngineering,1987,113(8)
[5]Ishihara K,Yoshimine M.Evaluation of settlementsinsanddeposits following liquefaction during earthquakes[J].Soilsand Foundations,Japanese Society of Soil Mechanics andFoundation Engineering,1992,32(1)
[6]崔卫国,符圣聪.饱和砂土层的震陷估计[J].工程勘察,1993,(4)Cui Wei-guo,Fu Sheng-cong.Estimation of settlements insaturated sand deposits after earthquake[J].GeotechnicalInvestigation&Surveying,1993,(4)
[7]符圣聪,江静贝.简化的液化判别概率法[J].工程抗震与加固改造,2008,30(3):93~98Fu Sheng-cong,Jiang Jing-bei.A simplified probabilisticmethodfor liquefaction evaluation[J].Earthquake ResistantEngineering and Retrofitting,2008,30(3):93~98
[8]刘恢先.唐山大地震震害(第一册)[M].北京:地震出版社,1985Liu Hui-xian.The Great Tangshan Earthquake of 1976[M].Beijing:Seismic Press,1985
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