超载高度及软土层厚度对卸载标准影响研究

Study of Unloading Control Standards under Different Preload Height and Different Soft Soil Thickness

根据"佛山一环"沉降观测数据和地质勘查资料,通过模拟分析不同预压载荷、软土层厚度下路基土的沉降变形规律,对排水固结法处理路段的卸载标准问题进行分析。结果表明,满载预压时间相同时,累计沉降量和沉降速率随超载高度、软土层厚度的增加而增大;增加超载高度能缩短预压时间,根据剩余沉降量确定卸载标准时应考虑载荷增加对路基计算深度的影响;排水体系正常工作条件下,等载预压满6个月、沉降速率小于5 mm/月,工后沉降通常小于300 mm;当欠载高度超过1 m时,单靠延长预压时间难以使路段的工后沉降量满足要求。

Combined with the settlement observation data of Foshan one ring road,by the way of settlement simulation of different preload height and different soft soil thickness,the unloading control standards for the section treated by drainage consolidation method was studied in this paper.Based on these results,some useful conclusions are drawn from the discussion and analysis.The total settlement and post-deposition settlement velocity increases with the raise of preload height and soft soil thickness in the condition of preloading time equality.Raise the preload height can be helpful to shorten the preload-ing time,but the increased settlement caused by the increased load must be considered if the unloading control standards are determined by the residual settlement.If the drainage system can work normally, the equal preloading period at least six month and the settlement velocity is less than 5 mm per month,the post-construction settlement always less than 300 mm.Post-construction settlement can not meet the re-quirements if the preload height shorten more than 1 m by the way of extend preloading time alone.