杭州湾粉质土液化后强度及变形特性试验研究①

吕小飞, 李冬, 陈培雄, 陈小玲

(国家海洋局第二海洋研究所工程海洋学研究中心，浙江 杭州 310012)

摘要：海洋粉质土因沉积环境的差异，在动应力作用下的液化特性与陆上粉土略有不同。以杭州湾原状粉质土为研究对象，进行特别设计的动三轴液化试验，研究粉质土液化后的强度和变形特性。研究表明：杭州湾粉质土液化后的应力-应变关系相似，应变与砂性土的变化规律相似，可分为低强度段和强度恢复段两阶段，振动频率、围压和前期最大轴向应变对液化后应力-应变都有影响。提出粉质土液化后二阶段本构模型能较好地反映粉质土液化后的应力-应变关系。

关键词：海洋粉质土； 液化后变形； 非零有效应力状态； 零有效应力状态

收稿日期：①2014-08-20

基金项目：国家海洋局第二海洋研究所基本科研业务费专项资助项目(JG200807)

作者简介：吕小飞(1978-)，男，浙江金华人，硕士，主要从事海洋土工程性质研究。E-mail：Lvxf@sio.org.cn。

中图分类号:TU41文献标志码：A

DOI:10.3969/j.issn.1000-0844.2015.03.0857

Experimental Study of Post-liquefaction Strength and Deformation

Behavior of Silt in the Hangzhou Bay

LV Xiao-fei, LI Dong, CHEN Pei-xiong, CHEN Xiao-ling

(LaboratoryofEngineeringOceanography,SecondInstituteofOceanography,SOA,Hangzhou310012,Zhejiang，China)

Abstract：The liquefaction behavior of marine silty soil is different from that of sandy soil under dynamic loading conditions. The samples of insitu marine silty soil in the Hangzhou Bay were analyzed with a special dynamic triaxial liquefaction test, which could possibly clarify post-liquefaction strength and deformation behavior. The results showed that the shear strain of silty soil could be divided into two parts: nonzero effective stress state and zero effective stress state, and the deformation law of marine silty soil was similar to that of sandy soil and also the shear strain when the nonzero effective stress state or zero effective stress state was subject to vibration frequency, cell pressure, and εmax. constitutive model on the post-liquefaction behavior of silty soil is proposed, which could express the post-liquefaction stress-strain response very well.

Key words： marine silty soil; post-liquefaction deformation; nonzero effective stress state; zero effective stress state

0引言

自1964年日本新泻地震和美国阿拉斯加地震后，地震液化问题逐渐引起岩土工程界的重视[1]，并成为该领域长期研究的热点[1]，具有重大理论价值和实际意义。Seed等[2]在1966年提出了“初始液化”概念，即认为在不排水循环剪切试验中有效应力第一次达到零值时砂土所处的状态为初始液化，并把砂土液化过程分为“初始液化前”和“初始液化后”两个阶段。从20世纪60年代开始至80年代，地震液化问题的研究主要关注砂土液化前，集中在液化的产生、液化机理、影响因素和液化的判别，取得了较大的成就。……