摘要
位于川西高原雅砻江两河口水电站库区的杜米村移民安置点由于切坡建房,诱发后山斜坡强烈变形,威胁移民安置点和S220省道安全。首先,基于现场调查、测绘、钻探、槽探等勘查手段,查明了滑坡发育的工程地质条件和变形特征;通过对滑体和滑带土开展室内直剪、反复剪试验,以及对滑床基岩进行抗压强度试验,结合反分析,合理确定了滑坡稳定性计算参数。然后,采用有限元程序Phase 2建立滑坡数值计算模型,模拟再现了滑坡在开挖前、开挖后、降雨后的应力、变形特征和稳定性变化过程,在此基础上分析了滑坡的变形机理。研究认为:不良的地形地貌、地质结构和地下水是滑坡发生的内在因素,坡脚开挖是滑坡变形启动的诱发因素,后期持续降雨入渗是滑坡变形加剧直至失稳破坏的直接因素;开挖导致滑体前缘抗滑力降低、滑带和开挖边坡坡脚产生剪应力集中是滑坡变形启动的力学机制,而饱水和持续剪切变形导致滑带土强度不断衰减接近饱和残余状态是滑坡变形加剧的本质原因;滑坡的变形破坏模式为牵引式蠕滑-拉裂。最后,采用有限元强度折减法对加固治理后的滑坡稳定性进行了计算分析。结果表明:天然条件下滑坡变形主要出现在桩后填土,降雨条件下变形范围扩大至强变形区,地震条件下变形范围进一步扩大至整个滑坡范围;三种工况下滑坡的稳定系数均能达到设计要求,表明加固设计方案和工程结构参数是合理的。研究成果可为类似滑坡工程案例的机理研究及防治提供参考。
The back slope of the Dumi village resettlement site,located at the Lianghekou hydropower station reservoir area in Yalong River,Western Sichuan Plateau,has experienced strong deformation,which has been posing a great threat to the safety of the resettlement site and the provincial highway S220.Firstly,the engineering geological conditions and deformation characteristics of the landslide were determined based on field investigation and exploration efforts such as surveying,mapping,drilling,and trenching;the calculational parameters for the stability analysis of the landslide were determined reasonably through direct shear and repeated shear tests of the sliding mass and sliding zone soil,compressive strength tests of bedrock combined with back analysis.Then,a numerical model of the landslide was established,and the stress,deformation characteristics and stability change process of the landslide were simulated using the finite element program Phase ^(2) for the three stages of pre-excavation,post-excavation and post-rainfall,respectively.On this basis,the deformation mechanism of the landslide was analyzed.It is concluded that the unfavorable topography,geological structure and groundwater were the internal factors for the landslide occurrence,toe excavation was the triggering factor for the initiation of the landslide,and continuous rainfall infiltration was the direct reason for the intensified deformation as well as failure.The decrease of sliding-resistant force at the front edge of the landslide mass caused by excavation,and resultant shear stress concentration at the slip zone and slope toe were deemed as the mechanical mechanism for the initiation of the landslide.The shear strength of the slip zone decreasing to a saturated residual state due to immersion in water and continuous shear deformation was inferred be the essential reason for the intensified deformation of the landslide.The deformation and failure mode of the landslide was pull-type creeping-cracking.Finally,the stability of landslide after reinforcement was calculated and analyzed using the finite element strength reduction method.The results show that the landslide deformation mainly occurred in the filling soil behind the piles under natural condition,the deformation range enlarged to the strong deformation area under rainfall condition,and further expanded to the whole landslide area under earthquake condition.Stability factor of landslide under three working conditions all meet the design requirements,indicating that the design scheme of reinforcement and engineering structural parameters were reasonable.The research results could provide a significant reference for the mechanism research and prevention for similar landslide cases.
作者
冉涛
陈浩
王羽珂
夏晨皓
杨东强
崔炎宗
方甜
RAN Tao;CHEN Hao;WANG Yuke;XIA Chenhao;YANG Dongqiang;CUI Yanzong;FANG Tian(Chengdu Center of China Geological Survey,Chengdu,Sichuan 610081;Nuclear Industry Southwest Geotechnical Investigation&Design Institute Co.,Ltd.,Chengdu,Sichuan 610061;College of Geosciences and Engineering,North China University of Water Resources and Electric Power,Zhengzhou,Henan 450045;College of Earth Science andEngineering,Shandong University of Science and Technology,Qingdao,Shandong 266590)
出处
《地质与勘探》
CAS
CSCD
北大核心
2022年第6期1236-1251,共16页
Geology and Exploration
基金
中国地质调查局项目(编号:DD20221811、DD20211379)
第二次青藏高原综合科学考察研究(编号:2019QZKK0904)联合资助。
关键词
堆积层滑坡
开挖
变形机理
稳定性分析
数值模拟
强度折减法
accumulation landslide
excavation
deformation mechanism
stability analysis
numerical modeling
strength reduction method
