摘要
1920年海原地震触发了宁夏固原石碑塬大型黄土滑坡,黄土液化是滑坡产生的主要原因之一。通过对石碑源滑坡黄土动三轴试验研究,探讨了强震作用下石碑塬滑坡黄土的动力特性,并依据试验成果,从液化的地震强度条件、地层特性、水文地质条件等方面论述了石碑塬滑坡的形成机制。结果表明:相同围压下滑移区外饱和黄土的初始动弹性模量和达到相同动应变所需的动应力远远大于滑坡后壁和滑移区饱和带黄土,说明在同一地震动作用下滑移区外黄土较不易发生破坏。同时,对黄土的液化判定也表明滑移区外黄土不液化,滑坡后壁和滑移区饱和带黄土可能液化,并且液化的同时抗剪强度衰弱。石碑塬滑坡处于饱和状态的砂质黄土层在强烈的地震荷载作用下,孔隙水压力累积增长并伴随着残余变形的不断增大,最终饱和砂质黄土发生液化流滑;液化的同时,抗剪强度降低,结构遭到破坏。
In 1920,the Haiyuan earthquake triggered the large Shibeiyuan loess landslide in Guyuan of Ningxia,China.Loess liquefaction is one of the main causes of the landslide.Through studying the dynamic tri-axial tests of the Shibeiyuan landslide loess, the authors discuss the dynamic characteristics of the loess under the strong seismic loading.Based on the test result,this paper expounds the formation mechanism of the Shibeiyuan landslide from the seismic strength,stratum features,hydrogeological conditions of liquefaction.The test results indicate that under the same confining pressure,the initial elasticity modulus and dynamic stress needed to reach the same strain of the loess outside the slip zone are far more than that of the saturated zone loess from the back wall and slip zone of the landslide.This shows that the loess outside the slip zone is difficult to liquefy under the same seismic load.Also the test shows that the loess outside the slip zone can not liquefy while that from the back wall and slip zone can do,and at the time of liquefaction,the shear strength reduces,too.Under the strong seismic loading,the pore water pressure and strain of the saturated sandy loess layer continuously increase and finally the saturated sandy loess become liquefied. Meanwhile,the shearing strength reduces,and the structure is broken.
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第4期492-498,共7页
Journal of Chengdu University of Technology: Science & Technology Edition
基金
中国地质调查局项目(1212011140005)
国家重点基础研究发展计划项目(2014CB744703)
关键词
石碑塬滑坡
黄土液化
形成机制
孔压增长模式
Shibeiyuan landslide
loess
liquefaction
formation mechanism
mode
pore water pressure
