非饱和中等压缩性土地基沉降预测的研究

Investigation on unsaturated soil of medium-compression settlement prediction

为研究非饱和中等压缩性土地基各施工阶段的沉降特性,针对胶济客专沿线的工程地质情况,结合建设和运营过程中现场沉降监测、室内固结试验以及数值模拟等方法,研究了不同加固方法非饱和中等压缩性土地基的沉降规律、初始饱和度对非饱和土固结变形的影响等。结果表明:非饱和中等压缩性土地基在分级填筑的情况下,路基填筑期(4个月左右)可完成总沉降的75%以上,经过短期放置(4个月左右)可完成总沉降的90%以上;气相连续的非饱和粉质粘土,低饱和度时固结完成时间比高饱和度时缩短;不同加固方法对地基沉降变形特性影响不同;放置期的确定应考虑地基加固方法的不同,对于采用的三种加固方法,只要放置期不少于6个月,其工后沉降都满足无砟轨道沉降控制要求。

According to the engineering geology conditions of Jiaozhou-Jinan high-speed railway,the ground settlements characteristics with passage of time and the influence of initial saturation of unsaturated soil on consolidation time were examined by observations at site among different construction phases and consolidation tests.Further more,numerical simulation method was introduced to propose optimization reinforcement methods.The results show that settlements during the sub-grade filling phase can finish more than 75% of the total settlements,which can be completed more than 90% of the total after a short-term standing time（about 4 months） under the stage constructed sub-grade conditions.The silty clay of lower degree of saturation can shorten the consolidation time than the higher one with continuous gas phase.Different reinforcement methods have different influence on the characteristics of settlements and may be considered in the decision of standing time.The post-construction settlement can meet the requirement of ballastless track sub-grade at least 6 months after construction for the three reinforcement methods introduced.