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巴东新城区发育有黄土坡滑坡、赵树岭滑坡、太矶头滑坡、童家坪滑坡等多处大型古滑坡,研究库岸斜坡岩体结构特征对滑坡的治理有着至关重要的作用。本文基于巴东新城区白土坡和西壤坡两段库岸深300余米监测剖面的地质勘探资料,根据岩芯颜色、岩性和结构将巴东组第三段划分为24段;通过薄片鉴定、X射线衍射和岩芯精细测量分析库岸斜坡岩体处于滨海环境的海陆过渡相,岩性组合、岩层厚度、矿物组成及强度具有复杂的垂向分带特征;探讨了层间软弱带和大型滑坡的关系。研究表明:巴东新城区库岸斜坡巴东组第三段内发育有13层贯通的软弱带,表现为为富含泥质、结构破碎的泥质软弱夹层、构造碎裂岩、溶蚀改造带和软岩软弱带。在沉积成岩时经历了滨海相反复的海侵海退,软弱带多分布在沉积环境动荡的开阔台地(陆棚泻湖)和局限台地(潮间带)。巴东组第二、三段岩性及沉积环境属缓慢过渡,在构造作用下未发生明显的滑脱。沉积结构和后期构造共同作用形成了贯通软弱带,为大型滑坡发生提供了有利条件。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。
The development of Badong new landslides includes large loess landslides, such as Huangshupo landslide, Zhao Shuling landslide, Taijitou landslide, and Tongjiaping landslide. It is very important to study the structural features of bank rock mass in slope landslide management. Based on the geological prospecting data of the monitoring section of the reservoir banks of Baituo slope and Xiliqian slope in Badong new district, the third section of Badong formation is divided into 24 segments according to the core color, lithology and structure. Identification, X-ray diffraction and fine core measurement to analyze the sea-land transitional facies of bank slope rock mass in coastal environment. The lithology combination, rock thickness, mineral composition and strength have complex vertical zoning characteristics. Relationship with large landslide. The results show that there are 13 soft layers in the third section of Badong Formation on the bank slope of Badong New City, which are characterized by muddy and weakly interbedded shale, crustal structure and dissolution zone And soft rock weak belt. During sedimentary diagenesis experienced transgressive transgression of the seashore phase. The weak belts were mostly distributed in the open platform (continental shelf lagoon) and the confined platform (intertidal zone) where the sedimentary environment was turbulent. The second and third Member of Badong Formation lithologic and sedimentary environment is a slow transition, in the structure under the action of no significant slippage. Sedimentary structure and post-tectonic work together to form a through soft zone, providing favorable conditions for the occurrence of large-scale landslides. After the Three Gorges Reservoir is fully recharged, the weak zone will aggravate the deep deformation of the bank slope under the long-term action of groundwater.