舟曲县瓜咱坝3号滑坡成因机理分析及防治对策

Analysis of Genetic Mechanism and Prevention and Control Countermeasures of Guazanba No. 3 Landslide in Zhouqu County

为了对大型深层、复合型滑坡--舟曲县瓜咱坝3号滑坡进行科学合理的防治治理,通过现场工程地质勘察、稳定性评价、三维数值模拟计算等方法,研究了舟曲县瓜咱坝3号滑坡的类型、变形破坏演变过程特征、成因机理。结果表明:舟曲县瓜咱坝3号滑坡属于堆积层-破碎岩石的复合型滑坡,由反倾陡立层状岩体的倾倒切层变形破坏转化演变而来,具多条、多级、多层的滑动特征;滑坡成因机理为前缘大规模挖方以及冲沟持续冲刷,产生逐级牵引,使得滑坡后缘拉张裂缝、侧界剪切裂缝、前缘鼓胀裂缝、前缘剪出口、坡体裂缝不断发展;滑坡整体处于欠稳定状态。滑坡防治治理措施以前缘回填反压、桩板墙支挡、排截水等综合防治为主。

To understand a large, deep, and complex landslide - Guazanba No.3 Landslide in Zhouqu, Gansu, NW China, an on-site engineering geological investigation was conducted to evaluate the stability. Three-dimensional numerical simulation and other methods were used. The types, characteristics, evolution, and mechanism of deformation and failure of the landslide were studied. Results show that No. 3 Landslide was a composite landslide of accumulation-layer-broken-rock, which was resulted from toppling and cutting of anti-dip and steep layered rock masses, and characteristic of multi-body, multi-level, and multi-layer sliding. It was believed that the mechanism of the landslide was due to large-scale excavation, continuous gully-edge erosion, and resultant cascade dragging, and consequential trailing tension fracture, side shear fracture, front bulge crack, front shear opening, and slope crack developing. Our comprehensive evaluation of stability showed that the whole landslide body is currently unstable. To prevent it from developing, multiple countermeasures of front backfill, pile wall retaining, and water interception shall be implemented.