湿陷性黄土区客运专线车站工后不均匀沉降初探

Discussion on differential settlement of the station of passenger dedicated line in collapsible loess zone

结合现场监测数据和地质勘察资料,对具有一定坡度和深厚填土区域地基处理失效的原因进行了探讨。得到如下结论:(1)在黄土地区地面沉降可分为4个阶段即增长期、平稳期、加速期、以及最终稳定期,黄土的沉陷是造成沉降再次加速的原因。建议黄土地区沉降监测应该予以加长,以确定最终的稳定期。(2)黄土的沉陷不仅使地表发生不均匀沉降,也会改变黄土区桩基的力学性质,造成桩基下部土体的变形。单纯依赖桩的刚度来控制结构变形是存在风险的,也应该控制桩侧土体变形。(3)在具有坡度的黄土区域,地面标高较低的一侧土体胶结作用较弱,且该区域承担更大的上部填土荷载,这是导致地面标高低的区域发生更大变形的原因。

The reason of the failure of foundation treatment in a certain slope and deep artificial fill area is investigated by analyzing the site investigation and the settlement observation. The useful conclusions can be drawn： （1） the settlement in collapsible loess zone can be divided into 4 stages： the growth period, the stable period, the acceleration period and the last stable period. The increase of the rate of the ground subsidence is caused by the collapse of loess soil. The settlement observation time is suggested to be longer to assure the settlement of the construction in the last stable period. （ 2 ） the collapse of loess soil not only cause the differential ground subsidence, but also change the mechanical characteristics of pile foundation. Only relying on the stiffness of pile foundation to control the displacements of structure is dangerous, but the deformation of soil near the pile foundation should be considered as well. （3）When the foundation of the construction is in a certain slope, the cementation of soil grains in a low height is weaker than those in a high height, which causes the low area deforming largely.