典型黄土-古土壤系列浸水渗透及湿陷变形规律

The law of soaking infiltration and collapse deformation in typical loess-paleosol series

为查明典型黄土-古土壤系列地层结构的水分运移及湿陷变形规律,依托西安北至机场城际轨道项目于渭北黄土塬区所进行的大型试坑浸水试验,采用现场实时观测的方法,跟踪测试了无渗水孔条件下的湿陷性土层浸水渗透及湿陷变形。结果表明:在浸水前期,渗透水流以垂直运动为主,整体形态似一不断加大的"秤砣"形,随着水分运移至埋深较大土层时(约15.0m),水平运动开始加大,直至达到水分入渗扩散角界限,最终,浸润区及饱和区均呈现形似倒置"漏斗"的形态;受水分扩散的影响,沉降过程可划分为:初始浸水段-剧烈湿陷段-湿陷稳定段-停水孔压消散段-固结沉降段-沉降稳定段;古土壤层阻碍了水分的垂直渗透速度,并对其上土层的侧向扩散起到一定促进作用,停水后,则起到隔绝水分向下快速扩散的作用。研究结果为认识典型黄土-古土壤系列场地水分运移及湿陷变形规律提供了参考,也可为该地区未来工程建设提供指导及借鉴。

In order to investigate the law of moisture migration and collapse deformation of the typical loess-paleosol series,on the basis of water immersion test of the large test pits of Xi’an North-airport intercity rail transit in the loess tableland of Weibei,the real-time in-site observation was adopted,the soaking infiltration and collapse deformation of collapsible soil layer under conditions of non water seepage hole were traced and tested.The results show that:The movement of water immersion is dominated by vertical movement in the early stage.The whole form is like a continuous increase of“weight”shape.As the water moves to the deeper layer(about 15.0 m),the horizontal movement begins to increase until it reaches the boundary of water diffusion angle;The infiltrating and saturation area appear like inverted“funnel”form;secondly,under the influence of water diffusion,settlement can be divided into the following stages:the initial soaking stage-the drastic collapsible stage-the collapsible stable stage-the dewatering pressure dissipation stage-the consolidation settlement stage-the settlement stable stage;The paleosol layer hinders the vertical penetration rate of water and promotes the lateral diffusion of the upper layer.The research results provide a solid foundation for understanding the water migration and the law of collapsible deformation of the typical loess-paleosol series,also guidance and reference for the future project construction in this area.