非饱和黄土动力液化研究——以党家岔滑坡为例  

Dynamic liquefaction of unsaturated loess:a case study of Dangjiacha landslide

作　　者：张子东 张晓超[2] 任鹏[1] 崔雪婷 ZHANG Zidong;ZHANG Xiaochao;REN Peng;CUI Xueting(Sichuan Institute of Building Research, Chengdu 610081, Sichuan, China;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology, Chengdu 610059, Sichuan, China;Sichuan Testing Center for Construction Engineering, Chengdu 610081, Sichuan, China;China Southwest Geotechnical Investigation & Design Institute Co., Ltd., Chengdu 610052, Sichuan, China)

机构地区：[1]四川省建筑科学研究院有限公司,四川成都610081 [2]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059 [3]四川省建筑工程质量检测中心有限公司,四川成都610081 [4]中国建筑西南勘察设计研究院有限公司,四川成都610052

出　　处：《地震工程学报》2021年第5期1228-1237,共10页China Earthquake Engineering Journal

基　　金：四川华西集团资助项目(HXKX2018/030);国家自然科学基金(41702335);四川华西集团资助项目(HXKX2019/019)。

摘　　要：黄土具有极强的水敏性和动力易损性,黄土地区多次强震都引起过液化、滑坡等地质灾害,造成了严重的人员伤亡和财产损失,因此振动作用下高含水率黄土的液化问题不容忽视。在大量已有研究的基础上,以宁夏党家岔滑坡为例,研究振动作用下高含水率黄土的液化问题。现场调查发现高含水率滑带土并未达到完全饱和状态(饱和度达95%左右),在新鲜的芯样断面发现有明显的“流态化”液化破坏特征。借助室内试验和数值模拟技术,对党家岔滑坡非饱和黄土层的液化性能及液化发生机理进行分析。结果表明:(1)非饱和黄土层液化发生机理可概括为:地震作用下饱和黄土层孔隙水压力激增,高含水率非饱和黄土层孔压增长响应滞后,随着孔隙水压朝上部消散,地下水向上渗流,当平均有效应力接近0时,高含水率非饱和黄土层发生液化;(2)振动过程中不同饱和度黄土孔隙水压力增长响应具有滞后性,借鉴饱和黄土液化时孔压比的判别标准和Seed简化判别法,初步证实党家岔滑坡高含水率非饱和黄土层可发生振动液化,斜坡前缘和中部土体发生液化的初始饱和度范围分别为68.3%~100%和73.8%~100%,斜坡后缘土体不发生液化。Due to the strong water sensitivity and dynamic vulnerability of loess,many strong earthquakes in loess areas have caused geological hazards such as liquefaction and landslides,resulting in serious casualties and property loss.Therefore,the liquefaction of loess with high water content under vibration can not be ignored.Based on previous studies,taking Dangjiacha landslide in Ningxia as an example,the liquefaction of high moisture content loess under vibration was studied in this paper.The field investigation results showed that the slip soil with high water content did not reach complete saturation(about 95%).Obvious liquefaction characteristics of"fluidization"were seen on the fresh core sample section.The performance and mechanism of liquefaction in the unsaturated loess layer of Dangjiacha landslide were analyzed with indoor tests and numerical simulation.The results showed that:(1)The mechanism of liquefaction in the unsaturated loess layer could be summarized as follows:the pore water pressure of saturated loess layer increases sharply under earthquake,while the growth response of unsaturated loess layer with high water content lags behind.As the pore water pressure dissipates upward,the groundwater percolates upward.When the average effective stress is close to 0,the liquefaction of unsaturated loess layer with high water content occurs.(2)The growth response of pore water pressure of loess with different saturation has time delay.According to the criterion of pore pressure ratio of liquefied saturated loess and Seed simplified discriminant method,it is confirmed that unsaturated loess layer with high moisture content in Dangjiacha landslide has a tendency for seismic liquefaction.The initial saturation ranges of soil liquefaction in the front and middle of the slope are 68.3%~100%and 73.8%~100%,respectively,and the soil in the rear edge of the slope will not liquefy.

关 键 词：滑坡 非饱和黄土 液化性能 液化机理 数值模拟 

分 类 号：P315.9[天文地球—地震学]