摘要
鸡扒子滑坡位于四川省云阳县城东一公里处的长江北岸,它是老滑坡的部分复活。滑坡体积达15,000多万立方米,其中230万立方米已脱离滑坡进入长江洪水位以下,给航运带来了严重危害,造成了巨大的经济损失。本文根据详细的地表地质调查和钻孔资料,论述了老滑坡部分复活的地形地质背景,老滑坡的变形破坏过程及运动特征。结合1982年7月的暴雨特征,分析计算了孔隙水压力在滑坡复活中的作用。
Situated on the northern bank of the Changjiang(Yangzi,Yangtze)River,1km east to Yunyang,Sichuan Province,the Jipazi landslide represents partial revival of an old landslide.The total volume of the slide mass is up to more than 150 million cubic meters,of which about 2.3 million is being detached from the slide channel and sliding down below the flood level of the Changjiang River,thus bringing a serious danger to the navigation in this river segment and causing enormous economic losses.Based on the data obstained from a detailed surface geological investigation and drilling,this paper discusses the topographic-geologic setting for the partial revival of the old landslide,the process of its deformation and failure and the characteristics of its movement.Besides,the role of pore pressure in the revival of the old landslide is also analyzed in combination with the characteristics of the heavy rainfall that occurred in July 1982.During the rainstorm,a vast amount of surface water infiltrated into the old landslide mass,which,on the one hand,caused the soil in the landslide zone to be saturated with water and the shearing strength to decrease by a big margin and,on the other hand,caused the groundwater level to rise 10—30 meters higher than that in the lowwater season,with an average hydraulic gradient of about 190‰or so.Consequently most of the landslide mass was in a state of water saturation,resulting in enormous dynamic pressure and static buoyancy.The stability of the part recharged by the infiltration of a vast amount of surface water in the west of the old landslide decreased constantly and finally the slide mass lost stability;while the periphery that was not directly recharged by the infiltration was still in a state of stability.Hence the extraordinarily high pore pressure produced by a vast amount of groundwater that infiltrated into the slide mass resulted in partial revival of the old landslide.Calculations show that the landslide has a rather high stability(K=1.33—1.61)in the dry season.It is also stable in the rainy season when the precipitation infiltra tion is normal,but its stability factor diminishes with an increase in pore pressure(K>0.5).Its stability is reduced dramatically below the critical value(K=0.8—0.95)only when an extraordinarily big rainstorm occurs and surface drainage facilities do not work so that the landslide mass is strongly filled with water.This further shows that pore pressure has played dominant and triggering role in the process of revival of the old landslide.Finally,some concrete suggestions for the control of the landslide are given in this paper.
出处
《地质学报》
1985年第2期172-182,共11页
Acta Geologica Sinica
