辽宁台安砂土液化特性动三轴试验研究

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。

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

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 ud 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 Dr 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 Dr. When the Dr 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.