湖相软土物理力学特性及蠕变特性研究

【作者】 刘浩；

【导师】 李亮；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2011， 硕士

【摘要】 工后沉降的大小关系到线路的平顺以及行车的舒适和安全。软土蠕变是引起工后沉降的一个重要因素,研究软土的工程特性及其蠕变特性有重要意义。本文以某高速铁路为工程背景,对阳澄湖地区的软粘土展开一系列试验研究,并以试验结果为基础对该地区软土的工程特性和蠕变特性进行了较为系统的研究。获得以下成果：(1)基于最小二乘原理,以数理统计分析为手段,分析了阳澄湖地区软土物理指标、力学指标和物理力学指标之间的相关性,得出了相关参数间的回归方程。(2)基于一维压缩蠕变试验,分析了影响软土次固结特性的因素。研究表明：该地区软土的次固结系数与先期固结压力的相关性不大；次固结系数和固结压力的关系曲线可以用双曲线拟合；增大加荷比可以减小次固结系数；预压可以显著地减小次固结系数；加载时间间隔越长,次固结系数越小。(3)根据一维压缩蠕变试验结果,建立了软土次固结蠕变模型；把试验值与新建模型计算值进行了比较分析,并分析了超载预压减小次固结沉降的原因。结果表明：新建模型能反映软土次固结蠕变特性,能够预测次固结沉降随时间的发展。(4)基于一维应力状态下的广义开尔文蠕变模型,运用非线性最小二乘原理,反演分析了三维应力状态下的广义开尔文蠕变模型,其物理意义明确,提供了一种探求软土三维蠕变参数的新途径。更多还原

【Abstract】 Post-construction settlement plays a significant role in line smoothness, driving comfort and safety of railway. Creep of soft soil is an important factor leading to post-construction settlement. Therefore, it is significant to study the engineering property of soft soil as well as its creep. Based on the background of high-speed railway, a series of tests were conducted to investigate the properties of soft clay in Yangcheng Lake area. On the basis of the test results, the engineering properties and creep of soft soil in YangCheng Lake area were studied systematically and the achievements were obtained as follows:(1) Based on least square principle and with the method of mathematical statistical analysis, the correlations among physical properties index and mechanical properties index of soft soil in Yangcheng Lake area were analyzed. Accordingly, the correlation equation among these parameters was obtained.(2) On the basis of the one-dimensional compression creep test, the factors which impact the secondary consolidation coefficient of soft soil were analyzed. The research result show that:①the secondary consolidation coefficient of soft soil in this area had no significant correlation with pre-consolidation pressure;②The curves of relationship between secondary consolidation coefficient and consolidation pressure can be better fitted with a hyperbolic curve;③The secondary consolidation coefficient decreases with load ratios increase;④Preloading can reduce the secondary consolidation coefficient significantly;⑤Secondary consolidation coefficient decreases with the extension of the load time interval.(3) According to one-dimensional compression creep test results, the model was established to simulate the secondary consolidation of soft soils creep. The comparison of experimental values and calculation values was conducted to analyze the reason that preloading with overload make the secondary consolidation settlement decreased. Further, the analysis results show that the new presented model can reflect the creep property of secondary consolidation of soft soil, also can predict the development of secondary consolidation settlement with time.(4) Based on one-dimensional generalized Kelvin creep model at stress state and the least square principle, the inverse analysis was conducted to analyze parameters of the generalized Kelvin creep models at 3d stress state. The physical meaning of this method is clear, and this study provides a new way to analyze the 3d creep parameters of soft soil.更多还原