中文摘要：

以南宁外环膨胀土为对象，开展含低应力条件的不同干密度、不同初始含水率、无荷和有荷干湿循环作用重塑样、有荷干湿循环作用原状样的饱和慢剪以及重塑样饱和三轴固结排水试验，研究干密度、初始含水率、无荷和有荷干湿循环作用等因素对其低应力条件下抗剪强度的影响。结果表明：各抗剪强度包线均呈非线性特征，可用广义幂函数很好地拟合；低应力、干密度及初始含水率对饱和慢剪强度的影响显著；试件初始含水率相同时，干密度越大，强度越大；干密度相同时，初始含水率越大，强度也越大；随干湿循环次数的增加，无荷条件下土样的抗剪强度衰减强于有荷条件。

英文摘要：

To study the influences of dry density,initial water content and dry-wet cycles with or without loading on shear strength under low stress,with Nanning expansive soil as obj ect, saturated slow shear tests were conducted on remoulded samples of various dry densities and initial water contents, and under dry-wet cycles with or without loading, and undisturbed samples under dry-wet cycles with loading.Saturated consolidated triaxial compression tests were conducted on remoulded samples.The results indicate that all shear strength failure envelopes are nonlinear,which can be fitted well by generalized power function.The saturated slow shear strength is greatly influenced by low stress,dry density and initial water content.The shear strength increases with the increase of dry density for the samples with the same initial water＆amp;nbsp;content.The shear strength increases with the increase of initial water content for the samples with the same dry density.The shear strength decreases greater for dry-wet cycles without loading than with loading,with the increase of dry-wet cycles.