巴东新城区巴东组第3段(T2b3)内广泛分布软弱带,通过钻孔岩芯分析、地表调查、X射线衍射、电镜扫描和物理力学性质试验,研究软弱带的特征。白土坡和西壤坡库岸深300余米的监测孔显示,库岸斜坡巴东组第3段内发育有13层贯通的软弱带,表现为富含黏土质的软弱夹层、碎裂岩软弱带、溶蚀改造软弱带和软岩软弱带。软弱带的矿物成分以绿泥石、伊利石、石英和方解石为主,黏土矿物含量变化较大,多者可达70%。软弱带经历了层间剪切变形,并牵引周围岩体形成较宽的破劈理或碎裂岩带,其微观结构显示的擦痕及矿物定向排列线理,揭示了软弱带经历了顺层剪切滑动,并伴有重力蠕滑特征。软弱带物理力学试验显示;在反复剪切和地下水长期作用下,其剪切强度将大幅下降。这些特征说明,三峡水库全面蓄水后,软弱带在地下水长期作用下必将加剧库岸斜坡的深部形变,进而发生沿软弱带的深部蠕滑。 The weak zone is widely distributed in the third block of Badong Formation in Badong New City (T2b3). The characteristics of the weak zone are studied by drilling core analysis, surface survey, X-ray diffraction, electron microscope scanning and physical and mechanical properties tests. Monitoring holes on the white soil slope and the Xilianpo reservoir bank of more than 300 meters show that there are 13 soft layers spreading through the third segment of the Badong formation in the bank slope, showing weak clay-rich intercalations and weak ripping rocks Belt, erosion reform soft zone and soft rock weak zone. The mineral component of weak zone is mainly chlorite, illite, quartz and calcite, and the contents of clay minerals vary greatly, with more than 70% of them. The weak zone experienced interlaminar shear deformation and led to the formation of broad broken cleavage or crushed rock zone around the rock mass. The micro-structure shows the scratches and mineral orientation alignment, revealing that the weak zone experienced bedding Shear sliding, accompanied by gravity creep characteristics. Weak band physical and mechanical tests show that under repeated shearing and groundwater long-term effects, the shear strength will drop dramatically. These characteristics show that after the Three Gorges Reservoir is fully impounded, the weak zone will deepen the deep deformation of the bank slope under the action of groundwater for a long time, and further the deep creep along the weak zone occurs.