不同水环境下含根马兰黄土的崩解性初探

通过野外调查发现,在黄土高原地区水土流失严重,降雨后浅表层滑坡多发生在植被发育良好的区域。推测其与黄土的崩解性这一水敏性质有关。为了探究边坡土体的崩解性发生的机理和草类根系在崩解发生时的作用。设计了不同水动力条件下含根马兰黄土和无根马兰黄土的崩解试验。结果发现,水进入土体后在孔隙中产生扩张作用,裂隙产生并扩张并延伸,土体崩解,最终破坏。动水对土体的作用包括崩解和搬运,静水对土体的作用主要是崩解作用。得到以下结论:(1)动水条件下,马兰黄土的崩解作用更加剧烈。(2)无根马兰黄土的崩解是由孔隙结构决定的,根系沿孔隙和裂隙生长,提高了渗透性,在土体中形成优势流,减弱了土体的崩解作用。(3)在动、静水环境下,草类根系的固结缠绕降低了土体的崩解性。并且,含根率越高,对崩解的削弱越多。

Preliminary Research on the Disintegration of Malan Loess with Roots in Different Water Environments

Soil and water loss is serious in the Loess Plateau,and shallow surface landslides mostly occur in areas with well-developed vegetation after rainfall according to the field investigation.It is speculated that it is related to the disintegration which is the water sensitivity of the loess.In order to explore the mechanism of the disintegration of slope soil and the role of grass roots in disintegration,disintegration tests of root Malan loess and rootless Malan loess under different hydrodynamic conditions are designed.As a result,water enters the Malan loess and expands in the pores,cracks are generated and expanded and extended,and the soil body disintegrates and eventually breaks down.The effect of moving water on soil includes disintegration and transportation.The effect of still water on soil is mainly disintegration.The following conclusions are drawn:①The disintegration of moving water on the soil is more intense.②The disintegration of rootless Malan loess is determined by the pore structure.The roots grow along the pores and fissures,which improve permeability,form dominant flow in the soil,and weaken the disintegration of the soil.③Under the dynamic and static water environment,the root-bearing soil reduces the disintegration of the soil.Besides,the higher the rooting rate is,the more the disintegration is weakened.