含水率对路基压实土小应变剪切模量的影响规律

Impact of moisture content on variation of small-strain shear modulus of compacted subgrade soil

运营期内路基土的含水率会由初始碾压含水率逐渐增大至平衡含水率,含水率的变化将会导致路基土路用性能的演化。结合已有文献中压实土剪切模量随含水率变化的实测结果与室内补充试验数据,研究了不同条件下含水率及压实度对压实土剪切模量的影响规律。结果表明:压实度不变时,路基土剪切模量随含水率的增加而减小,且压实度越大,剪切模量降低得越快;在低含水率下,剪切模量随压实度的增大而增加,但在较高含水率下,剪切模量随压实度先增加后降低,且峰值模量对应的压实度随含水率的增加而减小;峰值剪切模量对应的含水率略小于最大干密度对应的最优含水率;压实土剪切模量随稠度呈先增大、后减小的趋势,但不同黏粒含量的土体获得峰值剪切模量的稠度状态不同,且峰值模量对应的稠度与黏粒含量具有良好函数关系。

Moisture content of subgrade gradually changes from the initial compaction moisture to equilibrium moisture content during in-service period, which leads to the evolution of the subgrade soil road performance. By summarizing the measured results of shear modulus with compacted soil moisture content in literatures and complement experimental data, this paper investigates the effect of moisture content and the degree of compaction on the shear modulus of compacted soil. The results show that, when the degree of compaction is a constant, the shear modulus of subgrade soil decreases with increasing of moisture content. The shear modulus of subgrade soil decreases larger as degree of compaction increases. Shear modulus increases with increasing degree of compaction in low moisture contents. However, shear modulus increases first and then decreases with increasing of the degree of compaction in higher moisture contents. The degree of compaction corresponding to the peak modulus decreases with increasing moisture content. Moisture content corresponding to peak shear modulus is slightly less than the optimum moisture content corresponding to maximum dry density. Shear modulus of compacted soil increases first and then decreases with the increasing of liquidity index. But liquidity index corresponding peak shear modulus of different soils shows a good function with the clay content of soils.