川西鲜水河断裂带地质灾害发育特征与典型滑坡形成机理

Geohazard effects of the Xianshuihe fault and characteristics of typical landslides in western Sichuan

在对川滇地块鲜水河断裂活动习性、地质灾害发育特征、典型地质灾害实例和稳定性等分析的基础上，探讨了鲜水河断裂带地质灾害的发育特征与大型滑坡形成机理。认为鲜水河断裂对该区内地质灾害有明显的控制作用：①断裂带内岩体结构破碎程度高，导致滑坡沿断裂带呈带状分布，约32.5%的地质灾害发育于距断裂带0.5km范围内，19.77%的地质灾害发育于距断裂带0.5~1.0km内，15.22%的地质灾害发育于距断裂带1.0~1.5km内，滑坡的滑动方向多垂直于断裂走向；②八美“土石林”是在断裂活动作用下形成的碎裂岩体，该类岩体力学强度低，稳定性差，滑坡灾害发育密度大；③断裂带内地震滑坡发育，在强震作用下形成的部分滑坡滑动彻底，现今稳定性较好；在地震作用下部分滑坡处于裂而未滑状态，在适当的外力作用下可发生失稳滑动；④断裂带穿越的斜坡或古地震滑坡，在断裂持续活动作用下，稳定性差并多次发生活动；⑤强降雨在一定程度上加速了断裂带坡体变形和地质灾害的发生频率。

With the geological hazard effect of the active fault as the main study object and on the basis of the development and activi？ty characteristics of the Xianshuihe fault, geo-hazards distribution characteristics, typical geohazards characteristics and stability analy？sis and other aspects, this paper deals with the geohazard distribution characteristics and formation mechanism of main typical big land？slides. The findings indicate that the Xianshuihe fault exerts significant controlling effect on landslides： ①the rock is of highly broken along the fault zone, resulting in zonal distribution of landslides along the fault, and about 32.5%of the geohazards are developed less than 0.5km from the fault zone, 19.77%developed 0.5~1.0km from the fault zone, and 15.22%developed 1.0~1.5km from the fault zone, with the landslide sliding direction mainly perpendicular to the fault; ②Bamei soil-stone forest is composed of shattered rocks formed under the faulting effect, characterized by low rock mass mechanics strength, poor stability and high landslide development density; ③the seismic landslides are well developed in the fault zone, some landslides slide thoroughly in the earthquake and show good stability;some landslides are partially in crack-sliding state formed in the earthquake, and are likely to slide under some external force;④under the sustained activity of the fault, the slopes or the ancient seismic landslides penetrated by the fault are in poor stability and might experience several times of activities; ⑤to a certain extent, the heavy rain could accelerate the fault slope deformation and increase the frequency of geohazards.