三峡库区万州塘角1号滑坡滑带特征研究

Study on the Sliding Zone Features of Tangjiao NO.1 Landslide in Wanzhou Country in the Three-Gorges Reservoir Area

三峡库区顺坡向缓倾角滑坡灾害频发,万州塘角1号滑坡具有该种滑坡的典型特征。在对该滑坡详细调查研究、GPS观测及深部位移监测数据分析的基础上,通过钻探工程,探井开挖及大型现场剪切试验对该滑坡的滑带特征及力学性质进行了综合分析。研究结果表明:滑坡体表现为持续蠕滑,前缘比中部和后缘变形要大,其方向为NNW向,滑带埋深在10～21m,滑面呈波状起伏。探井揭露滑体中碎块石排布具有定向性和分段性特点,该滑坡存在多层次级滑动,认为在5.0～8.0m范围内存在一规模较大连续性较差的次级滑动带,受主滑带控制。滑坡各区的力学强度表现为不均一性,在滑坡前缘滑带土剪切强度比中部大,这主要是因为在中部地下水相比前缘要丰富,加上滑带土主要为粘土矿物,遇水膨胀软化致使强度降低。

Along slopes gently inclined landslides often occur in the Three-Gorges Reservoir area and the Tangjiao No.1 landslide in Wanzhou Country has the typical characteristics.Based on the detailed investigations of the landslide,GPS observations and deep displacement monitoring data analysis,through borehole engineering,exploration well excavation and field shear tests,this paper comprehensively analyzed the features and mechanical properties of sliding zone in the landslide.The results showed that the landslide manifested as a continuous creep,and the deformation of the leading edge is more obvious than that of the middle and back edges with the direction striking NNW.The burial depth of the sliding zone is from 10 m to 20 m and the sliding face is of undulation.The crushed stones in the exploration well display directivity and segmentation.The segmentation reflects multi-level sliding in the landslide,which were controlled by the main sliding zone among the secondary sliding zones with large-scale and bad continuity at the depth of 5.0 m to 8.0 m.The mechanical strength in different areas of the landslide manifested as heterogeneity,i.e.,the shear strength of the leading edge is higher than that of the middle edge.That is because the groundwater at the middle edge is more abundant than at the leading edge and the sliding zone is composed mainly of clay minerals that are softening when they meet with water.