高填方土石混合料强度与变形特性及沉降预测研究

Strength and deformation characteristic of soil-rock mixture and settlement prediction in high filled projects

为解决高填方土石混合料强度与变形计算难题,对不同初始含水量不同初始干密度的土石混合试样进行剪切试验和压缩试验,深入分析不同土石比试样的强度与变形特性随初始参数的变化规律。结果包括:(1)初始压实度越小的试样侧限压缩应变越大,初始含水量越大的试样侧限压缩应变越大;压缩系数随竖向压力的增大整体先增大后减小,压缩模量随竖向压力的增大整体呈增大趋势;(2)类似高填方工程中填筑体初始压实度宜控制在0.93以上,初始含水量控制在最优含水量±(2%~3%),土石比控制为2∶8~4∶6;(3)粉质黏土和砂质泥岩混合料压实土的干密度与竖向压力之间呈幂函数关系,建立由填土层的初始状态和所受荷载预测填筑土层强度和沉降量的算法;(4)考虑初始状态的填方沉降预测方法是合理的,采用其略微偏大的变形计算结果进行高填方设计或施工,可使得高填方地基质量控制偏于安全;(5)最优含水量范围内不同压实系数引起的沉降差异较小;随着压实系数的增大,地基沉降变形明显减小;土石比为2∶8时压实度增大对地基沉降的影响程度大于土石比为4∶6的高填方地基。研究成果可用于土石混合料高填方地基变形分析与计算。

Shear tests and compression tests were carried out for soil samples of different initial water contents and initial dry densities in order to investigate the strength and deformation of soil-rock mixture in high filled projects. The shear strength and deformation of different soil-rock ratios varying with initial parameters were analyzed in detail. The smaller the initial degree of compaction is,the larger the confined compression strain of the specimen is. The larger the initial water content is,the larger the confined compression strain of the specimen is. The compression coefficient increases firstly and then decreases with increasing the vertical pressure. The compression modulus increases with rising the vertical pressure. The initial degree of compaction in the similar hill filled projects should be controlled to be more than 0.93,the initial water content should be controlled around the optimum water content within 2% to 3% of error,and the soil-rock ratio should be controlled between 2∶8 and 4∶6. The relationship between the dry density of the compacted mixture of silty clay and sandy mudstone and the vertical pressure is a power function. An algorithm was established to predict the strength and settlement according to the initial state and the loads of filled soil layer. The difference of settlement caused by the different compaction coefficient in the range of optimum water content is small. The settlement and deformation of foundation decrease obviously with the increase of compaction coefficient. The influence of compactness on the settlement of foundation when the ratio of soil to rock is 2∶8 is greater than when the ratio of soil to rock is 4∶6.