辽宁台安砂土液化特性动三轴试验研究  

Dynamic triaxial test on liquefaction characteristics of sandy soil in Tai'an,Liaoning Province

作　　者：刘钢 郭文博[1,2] 赵明志 张冲 LIU Gang;GUO Wenbo;ZHAO Mingzhi;ZHANG Chong(School of Civil Engineering, Architecture and Environment, Xihua University, Chengdu 610039, Sichuan China;Institute of Geotechnical Engineering, Xihua University, Chengdu 610039, Sichuan, China)

机构地区：[1]西华大学土木建筑与环境学院,四川成都610039 [2]西华大学岩土工程研究所,四川成都610039

出　　处：《地震工程学报》2022年第3期558-569,共12页China Earthquake Engineering Journal

基　　金：国家自然科学基金(51878560);国家自然科学基金青年基金项目(51408491);教育部春晖计划项目(z2016155)。

摘　　要：为探讨台安砂土液化相关特性及发展规律,针对辽宁台安砂土进行一系列不排水动三轴试验,研究台安砂土在动荷载作用下动孔压及动应变变化规律,分析影响台安砂土发生液化的主控因素,揭示动载作用次数下台安砂土动力响应特征。结果表明:动应力水平不同的各相对密度试样u_(d)曲线可分为后期陡增和匀速增长两种类型,动应力幅值较大时,u_(d)始终以较快速度增长,呈现匀速增长特征,动应力幅值较小时,u_(d)曲线则呈现初期缓增后期陡增的特点;相对密度D_(r)和动应力幅值CSR是决定砂土液化的主控因素,在同一里氏震级等效动载作用次数下,随着D_(r)持续发展,液化所需CSR增长逐渐加快,当D_(r)足够大时,砂土基本处于密实状态,此时难以发生液化;循环荷载作用下,台安砂土呈现出初期整体受压、中期拉压平衡、后期受拉凸显的动力响应特征,到后期试样拉应变迅速增大,试样易发生受拉破坏。研究成果可为辽宁台安地区建筑物抗震设计提供参考依据。To explore the characteristics and development law of sand liquefaction in Tai'an County,Liaoning Province,a series of undrained dynamic triaxial tests were carried out to study the variation of dynamic pore pressure and dynamic strain of Tai'an sand under dynamic load.The main factors affecting the sand liquefaction were analyzed,and the dynamic response characteristics of sandy soil under dynamic loads were revealed.The results showed that the u_(d) curves of samples with different dynamic stress include two types:steep increase in the late stage and uniform increase.When the dynamic stress amplitude is large,the u_(d) increases at a fast rate,showing the characteristics of uniform increase;when the dynamic stress amplitude is small,the u_(d) curve slowly increases in the initial stage and steep increases in the later stage.Relative density D_(r) and dynamic stress amplitude CSR are the main factors that determine the liquefaction of sand soil.Under the equivalent dynamic load,the CSR gradually accelerates with the continuous development of D_(r).When the D_(r) is large enough,the sand soil is basically in a dense state and liquefaction is difficult to occur.Under the action of cyclic load,the dynamic response of Tai'an sand include three stages,i.e.,overall compression,tension-pressure balance and tension in the initial,middle and later stages,respectively.At the later stage,the tensile strain of the specimen increases rapidly,which is prone to tension failure.The research results provide a theoretical support for the seismic design of buildings in Tai'an area,Liaoning Province.

关 键 词：饱和砂土 液化特性 动孔压 动应变 滞回曲线 

分 类 号：TU43[建筑科学—岩土工程]