孔压增速对黄土静态液化特性影响试验研究  

Influence of increasing in pore water pressure gradient on static liquefaction characteristics of loess

作　　者：段钊[1,2] 李珍艳 牛兵 吴延斌 DUAN Zhao;LI Zhenyan;NIU Bing;WU Yanbin(Institute of Ecological Environmental Restoration in Mine Areas of West China,Xi’an University of Science and Technology,Xi'an 710054;College of Geology and Environment,Xi’an University of Science and Technology,Xi'an 710054;Machine Industry Investigation Design Institute Co.,Ltd,Xi’an 710054,China)

机构地区：[1]西安科技大学西部矿山生态环境修复研究院,西安710054 [2]西安科技大学地质与环境学院,西安710054 [3]机械工业勘察设计研究院有限公司,西安710043

出　　处：《干旱区资源与环境》2022年第6期179-186,共8页Journal of Arid Land Resources and Environment

基　　金：国家自然科学基金(42177155,41702298,41790442);中国博士后基金(2020M683676XB)资助。

摘　　要：为探究孔压增速变化对黄土静态液化特性的影响,选取泾阳南塬黄土为研究对象,通过对饱和重塑黄土进行常剪应力排水剪切(CSD)应力路径试验,研究了不同孔压增速下黄土的力学行为过程与液化临界条件,在此基础上探讨了黄土静态液化机理。结果表明:在孔压上升初期,试样应变增长十分缓慢,剪应力几乎不变,随着孔压的不断升高,有效应力降至临界状态,应变突然增加,剪应力也迅速降低,可将该破坏过程划分为平稳蠕动阶段和失稳剧动阶段。试样临界液化孔压比在0.48~0.66,且随着孔压增速的增加,试样所能承受的孔压越高,临界液化孔压比越大,破坏时达到的应力水平也越高。黄土液化发生的主要原因是饱水土体中局部孔压快速升高造成了不排水剪切破坏行为,在破坏过程中,由于颗粒重排和联锁结构的形成,试样会出现高-低速应变台阶现象。研究结果对于今后解决孔压变化导致的黄土滑坡力学机理有一定参考价值。This study aims at exploring the influence in increasing of pore water pressure gradient to static liquefaction of loess.The loess landslide area in the south Jingyang platform was selected as the research area and the samples were collected from there.Several groups of constant shear drained(CSD)stress path tests on saturated remolded loess were employed to study the mechanical behavior and critical liquefaction condition of the loess samples under different increasing in pore water pressure gradients.On this basis,the failure mechanism of the loess landslides owning to static liquefaction was discussed.The results showed that the strain of the samples increased slowly and the shear stress was almost a constant at the beginning period.Nevertheless,the strain started to increase sharply when the effective stress decreased to the critical state.Consequently,the failure process was divided into two stages:stable creep and sharply unstable deformation.The pore water pressure ratio of the samples at the state of critical liquefaction was 0.48~0.66.With the increase of pore water pressure gradient,the pore water pressure in the samples increased correspondingly,and the pore water pressure ratio increased at state of critical liquefaction,so that the sample reached a higher stress level when it was failure.The loess liquefaction was mainly contributed to the undrained shear failure behavior due to the sharply increase of local pore water pressure.There was alternatively high-low strain caused by the effect of particle rearrangement and inter-locking during sharply deformation failure.The results provide some references for relieving and preventing loess landslide due to a variation in pore water pressure.

关 键 词：液化特性 孔压增速 CSD应力路径 黄土 滑坡机理 

分 类 号：P642.131[天文地球—工程地质学]