非饱和压实土率敏性及蠕变时效特征试验研究

为研究部分饱和状态下高填方回填土工后长期变形，对非饱和压实土在可控基质吸力下分别开展率敏性和蠕变试验，并分析两者间时效对应关系。率敏性试验采取不同加载速率的三轴剪切，分析基质吸力（0、100、200、300 kPa）、加载速率（0.40、0.02 mm/min）以及超固结比（1、4和8）对土体强度和变形特征的影响，并确定三轴剪切蠕变的三级加载应力水平为抗剪强度的0.45、0.65、0.85倍；在4种可控基质吸力（0、100、200、300 kPa）下参考陈氏加载法，按三应力水平分级加载开展非饱和压实土三轴剪切蠕变试验。试验结果表明：随着基质吸力的增加，其率敏性参数ρ 减小，其率敏性降低；随着基质吸力逐渐增大，其蠕变初始最大速率、稳定蠕变速率以及蠕变变形量均显著减小；蠕变试验确定的应变速率?应变关系线与率敏性试验获得的应变速率?应变数据点基本吻合，证明两者间存在一定时效对应关系，且随着基质吸力的增大，这种时效对应关系更显著。

Experimental study on time-dependent characteristics of rate-sensitivity and creep of unsaturated compacted soil

To study the long-term deformation after construction of high-filled soil under partial saturation, the rate sensitivity and creep tests of unsaturated compacted soil under controllable matric suction were carried out respectively, and the time-dependent corresponding relationship between them was analyzed. The rate-sensitivity tests used the triaxial shear method at different loading rates to analyze the effects of matric suction (0, 100, 200, and 300 kPa), loading rate (0.4 and 0.02 mm/min), and over-consolidation ratio (1, 4, and 8) on the strength and deformation characteristics of the soil. The 0.45, 0.65, and 0.85 times of shear strength are determined to be the third-order stress level loads of triaxial shear creep respectively. The triaxial shear creep tests of unsaturated compacted soil were carried out under four controllable matric suction forces (0, 100, 200, and 300 kPa), referring to the Chen loading method, and under three stress level graded loading. The results show that: 1) The rate sensitivity parameter ρof unsaturated compacted soil decreases with the increase of matrix suction, and its rate sensitivity also decreases. 2) With the increasing of matric suction, the initial maximum creep rate, stable creep rate and creep deformation of unsaturated compacted soil decrease significantly. 3) The strain rate-strain relationship line determined by the creep test is consistent with the strain rate-strain data points obtained by the rate sensitivity test, which proves that there is a certain time-dependent corresponding relationship between the rate sensitivity and creep, and this relationship becomes more significant with the increase of matrix suction.