循环荷载下石灰改良膨胀土临界动应力的探讨

为探讨各影响因素对石灰改良膨胀土临界动应力的影响规律与程度,进行了振动三轴试验,获得了不同含水率与振动频率下石灰改良膨胀土的临界动应力.基于本文的试验结果,通过石灰改良膨胀土脆性破坏机理分析和临界动应力的影响因素探讨表明,由于石灰的改性作用,导致改良后膨胀土的塑性降低,表现出脆性性质;质量控制指标(掺灰比和压实系数)是影响石灰改良膨胀土临界动应力的决定性因素;由于改性后动力水稳定性较好,石灰改良膨胀土临界动应力受含水率变化的影响有限;而外部动静荷载形式与程度(振动频率和围压)的影响程度较弱.即在保证掺灰比和压实系数的前提下,石灰改良膨胀土的临界动应力能够维持在一个比较稳定的范围内.

Discussion on critical dynamic stress of lime-treated expansive soil under cyclic loading

In order to study the critical dynamic stress of lime-treated expansive soil under cyclic loading, the dynamic triaxial tests under different water contents and different vibration frequencies are carried out. Based on the test results, the analysis of brittle failure mechanism of lime-treated expansive soil under cyclic loading and the discussion on the affecting factors of the critical dynamic stress are carried out; it is shown that the plasticity of expansive soil decreases after lime treatment, and its brittle property appears; the quality control index (dosage of lime and compactness) is the decisive factor for the critical dynamic stress. And the influence of water content on critical dynamic stress of lime-treated expansive soil appears limited because of its preferable dynamic water stability. However, the influence of the type and the extent of external dynamic and static loads (vibration frequency and confining pressure) is so little. Namely, on condition of stable dosage of lime and compactness, the critical dynamic stress of lime-treated expansive soil is usually stable over a small range.