弯曲型倾倒变形边坡破坏模式研究

Study on failure mode of flexural toppling deformation slope

为了分析弯曲型倾倒变形边坡破坏模式,以西藏扎拉水电站为研究对象,分析了弯曲型倾倒变形边坡在天然状态、开挖工况下的破坏模式及其控制因素。结果表明:弯曲型倾倒变形边坡的破坏模式主要有表层剥落与崩塌、浅层滑移、深层或大规模失稳。(1)剥落与崩塌发生在坡表,在倾倒变形及卸荷、风化作用下,坡表岩体破碎,在降雨产生的坡面水流作用下易发生剥落、崩塌;(2)浅层滑移发育在强倾倒变形区,倾倒变形过程中产生的倾向坡外的张剪裂隙是边坡失稳的控制性结构面,当路堑边坡开挖或河水冲刷切脚时,边坡产生应力调整,导致倾向坡外的破裂面贯通,进而发生滑坡;(3)边坡发生深层或大规模失稳的控制因素是大断裂或活断裂、软弱夹层等软弱结构面。西藏扎拉水电站弯曲型倾倒变形边坡弯曲界面及深部弱倾倒变形区没有形成贯通性失稳界面,整体处于稳定状态。该工程区弯曲型倾倒变形边坡的发育特征和破坏模式具有典型性,研究成果可供类似工程借鉴。

In order to analyze the failure mode of flexural toppling deformation slope,taking Xizang Zhala Hydro-power Station as the research object,the failure mode and control factors of flexural toppling deformation slope under natural and excavation conditions were analyzed.The results showed that the main failure modes of the curved top-pling slope were surface spalling and collapse,shallow slip,deep or large-scale instability.Spalling and col-lapse usually occurred on the slope surface,and the rock mass on the slope surface was broken under the action of toppling deformation,unloading and weathering,and spalling and collapse were easy to occur under the action of slope flow generated by rainfall.②Shallowslippagedeveloped inthestrongtopplingdeformationarea,and theten-sio-shear crack generated in the process of toppling deformation was the controlling structural plane of slope insta-bility.When the cutting slope was excavated or the cutting foot was washed by the river,the slope would produce stress adjustment,which led to the penetration of the fracture surface outside the slope,and then landslide occurred.The controlling factors of deep or large-scale slope instability were weak structural planes such as large faults,active faults and weak inter-layers.However,the bending interface of the flexural toppling deformation slope of Xizang Zhala Hydropower Station and the deep weak tipping deformation area didn't form a penetrating instability interface,and the whole slope was in a stable state.The development characteristics and failure modes of the curved overturning slope in the project area were typical,and the research results can provide a reference for similar pro-jects.