砂土路用动态特性试验研究

EXPERIMENTAL STUDY OF DYNAMIC CHARACTERISTICS OF SAND FOR HIGHWAY SUBGRADE

为研究砂土在重复荷载作用下的路用动态特性,开展系列动三轴试验。根据累积塑性应变随加载次数的变化规律,获得不同含水量、压实度下砂土的临界动应力。研究结果表明,砂土动态回弹模量随围压、压实度的提高而增大,随循环偏应力和含水量的增大而减小。采用偏应力和体应力为变量的动态回弹模量本构模型对试验数据进行回归分析,结果表明所选模型具有较高的决定系数,证明所选模型具有较高的合理性与可靠性,可为基于动力学的路面结构设计提供参数。为运用上述动态特性评价公路路基填料,提出基于动力特性的公路路基设计思路。

To investigate the dynamic characteristics of sand for highway subgrade under repeated loads, a series of dynamic triaxial tests were carried out. According to the changing rule of accumulative plastic strain with loading cycles, the critical dynamic stress of sand under different compaction degrees and water contents were obtained. The experimental results demonstrate that dynamic resilient modulus values of sand increase with the increase of confining pressure and compaction degree, but decrease with deviatonic stress and water content. The dynamic resilient modulus constitutive model, which reflects the effects of bulk stress and deviatonic stress, was utilized for regression analysis of experimental data. A large coefficient of determination shows that the model is accurate and credible. The prediction model can provide parameters for pavement design based on dynamic method. In order to evaluate subgrade filling according to the above mentioned dynamic characteristics, the design principles for highway subgrade were put forward based on the dynamic characteristics of sand.