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高铁路基粗颗粒土的水力学特性对路基内部水分运移及路基的长期累积变形有重要影响。而对这种高压实度的粗颗粒土,常规非饱和土试验仪器存在试样尺寸小、制样难度大的缺点,难以应用。介绍了一种用于测试高压实度路基粗颗粒土-水力学参数的试验装置,利用张力计和时域反射计量器,分别测量路基粗颗粒土在浸湿、干燥阶段不同高度处土体基质吸力、介电常数的变化情况,获得高压实度下高铁路基粗颗粒土土-水特征曲线;并通过瞬态剖面法获得路基粗颗粒土非饱和渗透系数与基质吸力的关系。试验结果表明,该套装置能够适用于最大粒径为20 mm的粗颗粒土,试样压实度最大可达到0.95。通过对一组试验结果分析,并结合Ekblad等试验结果,发现随着填料细颗粒含量增大,?(与进气值有关的参数)值逐渐减小,土体进气值增加;粒径越大,细颗粒含量越低,土体储水能力越低,对应n(与排水程度有关的参数)值越大。为路基粗颗粒土-水力学参数的测定提供了方法。
The hydraulic characteristics of coarse grained soil in high-speed railway subgrade have an important influence on the moisture transport within subgrade and the long-term cumulative deformation of subgrade. However, for such coarse granular soil with high compaction degree, conventional unsaturated soil testing instruments have the disadvantages of small sample size and high sample preparation difficulty, which are difficult to be applied. A test device for testing soil-hydraulics parameters of coarse granular soil at high compacted subgrade was introduced. Tensiometer and time-domain reflectometer were used to measure the soil contents of subgrade soils at different heights of wetting and drying stages respectively. Matrix suction and dielectric constant, and get the soil-water characteristic curves of the coarse grained soil under high compaction. The relationship between the unsaturated permeability coefficient of the coarse grained soil and the matric suction is obtained by transient section method. The test results show that the device can be applied to coarse particles with a maximum particle size of 20 mm, and the compaction degree of the sample can reach as high as 0.95. By analyzing a series of test results and combining with the results of Ekblad et al., It is found that the? (Parameter related to intake value) decreases gradually and the value of soil intake increases as the content of fine particles increases; The lower the content of large and fine particles, the lower the water storage capacity of soil, the larger the value corresponding to n (the parameter related to drainage degree). It provides a method for the determination of coarse-grained soil-hydraulics parameters in subgrade.