Precise prediction of post-construction settlement of the high-speed railway is the key technology for design and construction.The traditional saturated soil settlement prediction curve model,when it is applied to unsaturated soil subgrade,has problems such as low fitting degree and small prediction value.A series of onedimensional consolidation tests of unsaturated soil were carried out to investigate the effects of matric suction and dry density on consolidation time of unsaturated soil.The parameter characteristics of settlement prediction model of unsaturated soil were investigated by experimental results.The measured settlement data of typical sections of Zhengzhou-Xi'an,Shijiazhuang-Wuhan and Qinhuangdao-Shenyang high-speed railways were used to analyze the characteristics and adaptability of the settlement prediction model of unsaturated soil.The results show that the matric suction has a significant effect on the consolidation time which increases first and then decreases with the increase of matric suction.Therefore,in a certain range of matric suction,the traditional settlement prediction curve model has the risk of small prediction value when it is used to predict post-construction settlement.Exponential and logarithmic relationship exists between the two parameters of unsaturated soil settlement prediction model and matric suction.The application examples show the advantages of proposed model with high fitting degree and emphasis on safety.%工后沉降的准确预测是高速铁路设计与施工的关键,传统饱和土沉降预测曲线模型在非饱和土路基应用中存在拟合程度低、预测值偏小等问题.通过室内非饱和土一维固结试验分析基质吸力与干密度对非饱和土固结时间的影响规律,验证非饱和土沉降预测模型参数特性;并结合郑西高速铁路、石武高速铁路和秦沈客专典型断面的沉降观测数据,对比分析非饱和土沉降预测模型的适应性.结果表明,基质吸力对非饱和土固结时间有显著影响:固结时间随基质吸力增加呈现先增加后减少的趋势,因此,在一定基质吸力范围内,传统沉降预测曲线方法预测工后沉降存在预测结果偏小的风险;非饱和土沉降预测模型的两个参数与基质吸力分别存在指数与对数关系;应用实例表明非饱和模型具有拟合度较高且偏于安全的优点.
展开▼
