【摘要】 黄土坡顶裂缝是黄土滑坡的重要诱因,探究其成因机理及演化过程对指导黄土区防灾减灾具有重要意义。在地质勘测和力学分析的基础上,提出了"五阶段"黄土坡顶裂缝的发育过程,即龟裂→发展→拉张→贯通→成型,认为黄土坡顶裂缝的发育成型是动态发展的过程,是外界蒸发、入渗,坡体内部水土相互制约、古土壤层"堵渗"、"阻裂"等多因素共同作用下的混合成因。干燥蒸发引起的地表龟裂是裂缝起始孕育阶段,此后地表蒸发和地表水入渗则极大地促进了裂缝的发展,这个过程是裂缝发育的龟裂阶段;不均匀的干燥收缩使裂缝尖端同时受拉张、剪切共同破坏作用,这个过程是裂缝发育的发展阶段;前期次滑坡,拉张坡顶裂缝的同时,使坡内原生结构面张开,这个过程是裂缝发育的拉张阶段;坡顶裂缝汇水有优先向坡内环状裂缝渗流的趋势,贯通后裂缝深度大为增加,这个过程是裂缝发育的贯通阶段;古土壤高强度、低渗透性的特征具有"阻渗"、"阻裂"效果,制约了裂缝的发展,这个过程是裂缝发育的成型阶段。最后,以陕西泾阳南塬庙店西村黄土滑坡为例,实证了上述裂缝发育阶段。更多还原

【Abstract】 Cracks on the top of loess slope are the important inducement of Loess landslide.It is important to study their mechanism and evolution process for guiding disaster prevention and mitigation in Loess area.On the basis of geological survey,law summary and mechanical analysis,this paper puts forward the "five stages" development mechanism of cracks on the top of slope in Loess area which is crack→development→tension→penetration→formation.It is believed that the development and formation of cracks on the top of loess slope is a process of dynamic development.It is a mixed cause caused by evaporation,infiltration and mutual restriction of internal soil and water.The surface crack caused by drying evaporation is the initial incubation stage of cracks,and then the surface evaporation and surface water infiltration greatly promote the development of cracks.The uneven drying shrinkage causes the crack tip to be destroyed simultaneously by tension and shear;the primary structural plane in the slope is opened when the cracks on the top of the slope are stretched in the early stage of the landslide;the catchment of the cracks on the top of the slope tends to flow preferentially to the circular cracks in the slope,and the depth of the cracks increases greatly after penetration.The characteristics of high strength and low permeability of Paleosol have the effect of "impermeability" and "crack resistance" which restrict the development of cracks.At the end,the paper takes the loess slope of Miaodian West Village in the south of Jingyang County,Shanxi Province as an example and verifies the development stage of cracks on the top of loess slope.更多还原