美姑河流域地质构造对大型滑坡孕育的控制作用

Development of the large-scale landslides controlled by geological structures in Meigu River Basin

地质构造及其活动特征与滑坡灾害的关系是工程地质研究中的热点问题。文章在川西南大凉山区美姑河流域地质构造资料分析和大型古滑坡精细化调查的基础上,以流域内的典型古滑坡为研究对象,结合该地区地质构造的几何学、变形学、运动学和活动性特征,深入剖析了沉积构造、断裂构造、褶皱构造和节理构造等不同的地质构造类型对大型古滑坡的孕育的控制作用,认为地质构造对大型滑坡的控制主要表现在:(1)断层破碎带、节理密集带等不连续结构面控制了滑坡发育的边界,(2)断层破碎带、褶皱弯滑作用的滑动层面、沉积结构软弱夹层等孕育滑带的形成,(3)节理构造形成的裂隙构成地下水储集和运移的通道,促进滑坡的孕育和大型滑坡的发生,(4)活动断裂制约着滑坡地貌发展演化,诱发断裂活动的地震导致了大型滑坡失稳。建议在美姑河流域的滑坡灾害防治方面应加强不同尺度,尤其是中小尺度活动构造与滑坡发育演化研究。

The relationship between geological structures with their action process and landslide hazards is a hot issue in engineering geological research area.Based on the analysis of geological tectonic data and the detailed investigation of large-scale ancient landslides in the Daliangshan mountain area of southwestern Sichuan,some typical ancient landslides in the basin were selected researched as the research objects.meanwhile.Combining the geometry,deformation,kinematics and active periods of the geological structures in the area,then the characteristics of different tectonics of sedimentary structures,fault structures,fold structures and joint structures to the formation mechanism and controlling of large-scale ancient landslides were analyzed in-depth.It is believed that the controlling action of geological active structures on large landslides is mainlyabout:(1)The boundary of landslide development controlled by fault fracture zone and jointed dense belt.(2)The formation of landslide sliding zone controlled by sliding layer,and weak interlayer of fault and fold fracture zones.(3)Some large-scale landslides occurred on the fissure formed by the joint structure constitutes a channel for groundwater storage and migration could promote the large-scale landslides development.(4)The development of large-scale landslide landform evolution restricted by the active fault,and the earthquakes induced by fault activity lead to the instability of large landslides.Therefore,it is suggested that different scales should be strengthened in the prevention and controlling to landslide disasters in the Meigu River Basin,especially study on small and medium-scale active structures and landslide evolution,which can provide technical support for landslides early identification and disaster prevention in the basin.