中文摘要：

非饱和石灰改良膨胀土应力松弛过程具有时间依赖性。通过应用非饱和三轴应力路径试验,系统研究不同加载方式、应变水平和应变速率的前期荷载对非饱和石灰改良膨胀土的应力松弛特性的影响规律。试验获得的应力松弛曲线形态基本相似,均为不完全松弛;对于前期荷载采用相同应变速率预加的应力松弛试验,应力松弛稳定历时随着预加应变水平的降低而增长,而松弛稳定曲线段对应的偏应力则随着预加应变水平的增大而降低;对于预加应变水平相同的松弛试验,应力松弛中初始偏应力值和松弛初始变化速率随着前期荷载加载速率的增大而增大;分级应力松弛过程中,试样破坏呈现累积损伤效应,且各级加载后的体积变化规律不同,并与应力松弛过程不同步,非饱和石灰改良膨胀土应力松弛过程中体积应变增长呈现出突变的特点。

英文摘要：

Stress relaxation is a major time-dependent behavior of unsaturated lime-treated expansive clay. In this paper,effects of loading mode,strain level and strain rate of primary loading on the subsequent stress relaxation were investigated by means of geotechnical digital system（ GDS） for unsaturated soils. The results showed that the incomplete relaxation occurred in the specimens. Patterns of measured curves were similar and of periodic fluctuations. For relaxation tests performed with the initial loading at constant strain rate,relaxation stable time increased with decreasing strain level employed prior to the initiation of the relaxation process,while the deviator stress in the stable stage decreased with the increment of the strain level. For specimens performed with the constant pre-loaded strain,the quicker the pre-loading employed,the higher initial relaxation rate. The phenomenon of cumulative damage was observed in specimens performed with stepwise loading mode,and the variation of volumetric strain during each relaxation step was different and did not correspond with that of deviatoric stress. The amount of volumetric strain increased sharply during the relaxation process.