饱和黄土动态液化和静态液化机理的差异性研究  

Difference between dynamic and static liquefaction mechanisms of saturated loess

作　　者：程超 钟秀梅[1,2] 刘钊钊 刘富强 江志杰 王谦[1,2,3] 陶冬旺 CHENG Chao;ZHONG Xiumei;LIU Zhaozhao;LIU Fuqiang;JIANG Zhijie;WANG Qian;TAO Dongwang(Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China;Key Laboratory of Loess Earthquake Engineering of CEA & Gansu Province, Lanzhou 730000, Gansu, China;Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080, Heilongjiang, China)

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]中国地震局(甘肃省)黄土地震工程重点实验室,甘肃兰州730000 [3]中国地震局地震工程与工程振动重点实验室,黑龙江哈尔滨150080

出　　处：《地震工程学报》2022年第1期136-144,共9页China Earthquake Engineering Journal

基　　金：地震科技星火计划项目(XH21034,XH20057);国家自然科学基金项目(51778590,U1939209);中国地震局地震工程与工程振动重点实验室开放基金项目(2020D17,2020EEEVL0409);甘肃省地震局科研团队建设项目(2020TD-01-01)。

摘　　要：饱和黄土在不同外荷载作用下其液化机理具有显著差异。为研究饱和黄土动态液化和静态液化机理的差异性,基于室内动三轴试验和静三轴试验,研究岷县永光饱和黄土动态液化后的动应力与轴向动应变关系、动孔隙水压力比与轴向动应变关系,分析其静态液化后的偏应力与轴向应变关系、孔隙水压力比与轴向应变关系,并结合液化前、后的SEM试验结果,研究动、静态液化对饱和黄土结构特征的影响,探讨两种液化机理的差异性。研究结果表明:饱和黄土在循环动荷载作用下,土骨架强度逐渐丧失,孔隙变形不断发展,从而导致孔隙水压力上升,直至出现具有流滑特征的动态液化;而在单调静荷载作用下,土体内的架空孔隙逐渐被压缩,落入孔隙中的土颗粒重新排列、组合,从而导致孔隙水压力增加,直至出现静态液化;动态液化后饱和黄土的表观孔隙面积比静态液化后的更小,孔隙均一性比静态液化后的更好,孔隙排列比静态液化后的更无序,孔隙结构相对于静态液化后更加复杂;两种液化机理的差异性主要表现在加载导致的细观结构变化过程差异引起的孔隙水压力增长模式不同。研究结果可为黄土地区液化灾害及液化诱发滑坡灾害的防治提供理论依据。The liquefaction mechanism of saturated loess varies significantly under different external loads.To study the difference between dynamic and static liquefaction mechanisms of saturated loess,a series of dynamic and static triaxial tests were conducted.The relationship between dynamic stress and dynamic strain,dynamic pore water pressure ratio and dynamic strain of saturated loess in Yongguang Village,Minxian County after dynamic liquefaction were analyzed.The relationship between deviatoric stress and axial strain,pore water pressure ratio and axial strain of the saturated loess after static liquefaction were also discussed.Based on the SEM test results before and after liquefaction,the effects of dynamic and static liquefaction on the structural characteristics of saturated loess were studied,and the difference of the two liquefaction mechanisms was discussed.The results showed that under cyclic dynamic loading,the strength of loess skeleton gradually loses and the pore deformation develops,resulting in the rise of pore water pressure until the dynamic liquefaction with flow slip characteristics occurs.However,under monotonic static load,the overhead pores in the loess are gradually compressed,and the soil particles falling into the pores are rearranged and combined,resulting in the increase of pore water pressure until static liquefaction occurs.Compared with static liquefaction,the apparent pore area of saturated loess after dynamic liquefaction is smaller,the pore uniformity is better,the pore arrangement is more disordered,and the pore structure is more complex.The difference between the two liquefaction mechanisms is mainly manifested in different growth modes of pore water pressure caused by the difference of meso-structure change process under different loads.The results may provide a theoretical basis for the prevention and control of liquefaction in loess area.

关 键 词：饱和黄土 孔隙水压力 黄土液化 细观结构 

分 类 号：P319.56[天文地球—固体地球物理学]