压实度与级配对路基重塑黏土土-水特征曲线的影响

对重庆路基黏土采用压力膜仪量测了不同压实度重塑土样脱湿过程的土-水特征曲线(SWCCs)、采用体积压力板仪量测了不同压实度、不同级配重塑土样脱-吸湿过程的土-水特征曲线。试验结果表明:(1)压实度超过90%以后,不同压实度的SWCCs在其直线段范围相互靠近,即在路基土基质吸力平常变化范围的SWCCs逐渐趋于稳定;(2)随着压实度的增大,脱-吸湿循环滞回圈逐渐上移,曲线由陡变缓。表明随着压实度的增大,土体的储水系数逐渐减小,土中的水分更不易吸入和排出,对路基的稳定有利;(3)相同含水率下,大约以压实度85%为界,压实度小于85%的黏土样和大于85%的黏土样的基质吸力基本上不随压实度(干密度)的变化而变化;(4)相同压实度和含水率状态下,粗粒含量多的土吸力更小,SWCCs的滞回圈更小,即干湿循环的影响更小。因此,粗粒土较细粒土更适合用作路堤填料。

Influence of compaction degree and gradation on SWCC of compacted clay soil

Under the circumstance of single-dehydration process and dry-wet cycle process, the soil-water characteristic curves (SWCCs) of Chongqing compacted clay soil samples with different compaction degrees and different gradations were respectively obtained by means of temple apparatus and pressure plate apparatus. The testing results show that: (1) After compaction degree exceeding 90%, the linear sections of SWCCs of the soil samples with different compaction degrees close each other, which indicates that the SWCCs gradually tend to stability within the common matrix suction changing scope of this compacted clay soil. (2) With the increment of compaction degree, the hysteresis loops of dry-wet cycle process gradually move upward, and the SWCCs change from steep shape to mitigative shape; this indicates that the moisture in the soil samples is more difficult to be intaken or drained out, which is beneficial to the stability of subgrade. (3) Under the same water content, there is a boundary of compaction degree of 85% for the compacted clay soil, the matrix suctions of the soil samples with less than or more than this compaction degree basically do not change with compaction degree changing. (4) Under the same compaction degree and water content, the matrix suctions of the soil samples with more coarse grained soil are more smaller; and the hysteresis loops of SWCCs are also smaller, which indicates that the influence of dry-wet cycle process on coarse grained soil is smaller. Therefore, coarse grained soil is more suitable for use as fill material of subgrade.