地基附加应力分布对城市路面塌陷的影响

Effects of Additional Stress of Foundation on Urban Road Collapse

基于对城市道路两侧建筑物地基附加应力分布的分析,从力学角度提出城市路面塌陷的内在机理,并将道路塌陷分为沉降拉裂隙的产生、降雨渗流运移、土洞扩张和路面坍塌等4个阶段。通过道路下方附加应力云图分析,表明路基下部天然土层因建筑物附加应力的不均匀分布可产生拉裂区。拉裂区的形成与否以及其形成规模受土体强度、附加应力值、建筑物基础类型和水的作用强度等因素影响。水的作用使得拉裂区在三维空间上相互贯通,形成城市路面以下的管涌系统;经地下水的潜蚀与运移作用,形成土洞并逐渐增大;最后,在路面车辆荷载的影响下导致路面塌陷。

The inherent mechanism of urban road collapse is proposed from the mechanical point of view by analyzing the distribution of additional stress of foundation of buildings base on both sides of urban road.The road collapse can be divided into four stages:the emergence of settlement cracks,rainfall infiltration and migration,soil cavity expansion and road surface collapse.Through analysis of the additional stress nephogram,it is shown that the natural soil layer in the lower part of the subgrade can produce tensile fracture zone due to the uneven distribution of the additional stress.In the threedimensional space,tensile zones are connected together and form the piping system below urban road.The water allows the piping system to develop into soil cave,and the soil cave gradually expends and finally collapse under the influence of road vehicle load.