关键词: 高速铁路, 路基, 膨胀土, 石灰改性, 临界动应力, 动三轴试验, 循环荷载, 脆性破坏

Abstract:

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.

Key words: high-speed railways, subgrade, expansive soil, lime treatment, critical dynamic stress, dynamic triaxial test, cyclic loading, brittle failure