卸荷条件下高边坡大规模开挖的“地质-力学”响应研究——以西藏如美水电站右坝肩为例

A study of the geological-mechanical response during large-scale excavation of high slope under unloading condition: exemplified by the right abutment of the Tibet Rumei Hydropower Station

以西藏如美水电站近700 m开挖边坡为例,通过现场卸荷的详细调查,对复杂地质条件下的岩质高边坡大规模开挖离散元模拟的变形响应进行了研究,得出此类边坡在卸荷条件下开挖后的变形响应过程、基本规律及地质-力学模式。模拟结果表明:高边坡大规模开挖之后,边坡的变形与开挖部位具有较强的联系,开挖面上部往往变形较大;边坡主要以浅表部碎裂岩体及深部的"滑移-拉裂"地质-力学响应为主导模式;边坡变形与开挖之后岩石卸荷有必然联系。随着开挖的继续,随着开挖面越来越远,坡体下部变形逐渐衰减,变形主要向开挖面上部累积,最终趋于稳定的响应特征。

The excavation slope of the Rumei Hydropower Station in Tibet(about 700 m high)is taken as an example in this paper.Through the detailed site investigation of the unloading,a study of the distinct element modeling deformation response of the large scale excavation is carried out on high rock slopes under complex geological conditions.This distinct element modeling gives the deformation response process,the basic laws and geology mechanics model of the slope under unloading conditions.The simulation results show that after the large scale excavation of the high slope,the deformation of the high slope has a strong connection with the position,and the upper part of the excavation face tends to have large deformation.The dominant modes of slope deformation are mainly the cataclastic rock mass in the shallow surface and the geological and mechanical response of slipping tension fracture in the deep part.There is a close relationship between the slope deformation and the rock unloading after excavation.With the excavation progresses,the slope deformation increases with the excavation,the deformation of the lower part gradually decreases,and the deformation mainly accumulates on the upper part of the excavation,and finally tends to be stable.