泥质板岩改良路基水稳性及长期动力稳定性研究

Argillite belongs to soft rock, which would disintegrate and soft in water. The mechanical properties of argillite which exposed widely in the expressway and high-speed railway line is poor,as so, argillite can not be directly used for subgrade filling, but if abandoned, the cost of the project would substantially increase and cause serious environmental pollution. After improvement, argillite has been used in the construction of subgrade, but how is the water stability and long-term dynamic stability, there is no research results, leaving great hidden dangers to the safety of engineering. This project is to deeply and systematically study the water stability and dynamic performance of argillite improved subgrade by means of indoor dynamic test, large scale model test, theory analysis and numerical simulation and its long-term dynamic stability will be evaluated by comprehensive methods. The researches include: verification test of subgrade improved scheme; indoor dynamic test and the results of dynamic parameters; the varying laws of dynamic velocity,dynamic acceleration,dynamic strain and dynamic stress in vertical and transverse test sections obtained by large scale model test; high-precision simulation analysis model built by the finite-infinite element coupling method and the results of simulation; comparative analysis of rationality of model and the experimental data. Finally the water stability and long-term stability of argillite improved subgrade will be talked over by comprehensive evaluation and the results would provide theoretical guidance and rationalization proposal for the similar type of subgrade construction.

泥质板岩属软质岩石，遇水易软化、崩解，路用性质差，在高速公路及铁路沿线广泛出露，一般不能直接用于路基填料，但如果弃之不用，将大幅增加工程造价，造成严重的环境污染。经改良后，泥质板岩已用于路基建设，但其水稳性及长期动力稳定性如何，目前尚无研究成果，给工程安全留下了极大的隐患。本项目拟采取室内动力试验、大型模型试验、理论分析和数值模拟等方法对泥质板岩改良路基的水稳性及动力特性进行深入、系统研究，综合评价其长期动力稳定性。包括：对改良路基方案进行验证试验；进行室内动力试验，获取动力参数；建立大比例模型试验，并通过大型激振及测试，获得振动速度、振动加速度、动应变及动应力等沿竖向及横向测试断面的变化规律；利用有限元-无限元耦合方法建立高精度数值分析模型，并进行静动力仿真计算，对比分析模型及试验数据的合理性；最后综合评价改良路基水稳性及长期动力稳定性，为该类型路基的使用提供理论指导和合理化建议。

为获取水泥改良泥质板岩路基土的合理配合比，利用击实试验、无侧限抗压强度试验研究水泥参入量对改良土的最大干密度和最优含水率的影响、以及不同水泥含量下的养护龄期、泡水作用和干湿循环作用对改良土强度的影响，从强度和水稳性等角度分析和探讨最优水泥含量的选取。为获取改良土的静力学特性和相关特征参数，设计了大型三轴静压缩试验，研究轴向应力 - 应变关系和体积应变 - 轴向应变关系的特性以及获得抗压强度、内摩擦角、黏聚力和弹性模量等力学参数；为评估干湿循环作用条件下水泥改良泥质板岩粗粒土的力学稳定性，设计干湿循环条件下的改良土大型三轴压缩试验。通过试验研究改良土抗压强度、内摩擦角、黏聚力和弹性模量等力学特征参数随干湿循环次数变化的规律以及分析围压和标准养护龄期对干湿循环效应的影响；为获取改良土的动力学特性和相关特征参数，设计了分别考虑循环动力作用和拟冲击荷载作用的影响的大型三轴动压缩试验，分别研究改良土在循环动力作用下的动弹模、阻尼比和累积变形以及在单调加载作用下加载应变率对动力强度的影响；建立了足尺的水泥改良泥质板岩土路基模型以及设计了相应的动力加载、测试系统，通过路基动力加载试验获取路基动力响应规律，评价长期泡水和干湿循环作用下路基的长期稳定性。建立了路基动力加载数值模型，通过matlab将改良土本构关系应用到ANSYS有限元程序中，进行数值分析。