【摘要】 中国西南三江活动构造带是大型滑坡的高发区。笔者在滇西北金沙江支流冲江河螺丝湾电站一带发现的巨型滑坡——冲江河滑坡,位于区域性活动断裂带的阶区,属于古地震造成的巨型古滑坡或坐落体,体积可达5.8×108m3。该巨型古滑坡在后期演化中经历了趋稳和局部再复活的过程,其内部存在若干次级滑坡,且表现出级序越低、稳定性越差的特点。在野外调查的基础上,对复活次级滑坡的滑带土进行了环剪试验研究,获得了不同部位滑带土在较大剪切位移条件下的抗剪强度变化规律,认为活动构造带斜坡岩体破碎软弱、坡脚处于应力集中区是冲江河巨型滑坡局部复活的重要因素;在剪切作用下,饱和或近饱和的滑带土因超孔隙水压力而发生液化作用,促进了坡体大变形的发生。试验结果很好地解释了公路坡脚部位,即使少量开挖就可以引起缓慢、持续发生的大变形现象。从滑坡复活机理角度,加强坡面排水和坡前采用抗滑桩技术可以有效控制坡体稳定性。更多还原

【Abstract】 The Sanjiang active tectonic zone in Southwest China is a large landslide-prone area.A giant landslide,named Chongjianghe landslide,is discovered near Luosiwan Power Station on the Chongjiang River,a branch of Jinsha River,in the northwestern area of Yunnan.The giant landslide is located at the step-fault zone of Zhongdian fault belt,belonging to a giant landslide caused by ancient earthquakes,with a volume of up to 5.8×108m3.The evolution process of the giant ancient landslide experiences a total stabilizing and local reactivations,and is characterized by grading and zoning.i.e.,the giant landslide includes a number of secondary landslides.Generally,the lower its level sequence is,the poorer its stability is.On the basis of field investigation,ring shear tests are completed on the sliding soils from the front edge and the back edge of the secondary reactive landslide respectively,and the shear strengths at different parts of sliding soil under large shear displacement are obtained.The test results show that the breakage and softness of the rock mass in the active tectonic zone,as well as the stress concentration in the slope foot,are important factors for local reactivation of the Chongjianghe giant landslide.Meanwhile,the liquefaction of sliding soil caused by the excess pore water pressure in saturated or nearly saturated soils contributes to the occurrence of large deformation of slope.The test results explain that even a small amount of excavation of the highway slope foot may cause slow,sustained large-deformation phenomenon.At present,such measures as drainage and pile driving should be taken to reinforce the secondary landslide.更多还原