降雨入渗对路基动力响应的变化规律研究

The change rules of dynamic response on subgrade under the rainfall infiltration

研究降雨入渗条件下高铁路基动力响应的变化规律对于识别路基潜在病害,保障路基稳定性有显著意义。通过1∶1大型现场模型激振试验,探讨高铁路基在降雨入渗条件下其内部动力响应的变化规律。研究表明,与正常工况相比,软化工况下的加速度和动应力均减小,越靠近路基表层,衰减量越明显,在路基表层,加速度和动应力的衰减量达到50%左右。软化工况下,沿路基中心沿深度方向上,动应力的衰减规律与加速度不同的是,动应力在软硬界面上出现界面效应,导致动应力在软硬交界处略有增大。动应力在路基中传播时存在应力扩散现象,造成路基下部的动应力幅值大于路基上部的现象。随着激振频率的增加,同一深度加速度衰减量先增大后减小,频率为19.1 Hz时达到最大值,动应力在距路基表面0.35 m内衰减量逐渐增大,0.35 m以下与加速度规律相似。

It is significant to study the change rules of dynamic response on high speed railway subgrade under the condition of rainfall infiltration,which can identify the potential disease and guarantee the stability of subgrade.Therefore,the change rules are discussed through the 1∶1 large-scale model test.Research suggests the acceleration and dynamic stress of the softening condition are both reduced compared with the normal condition.The more close to the subgrade surface,the reduction is more obvious,and the reduction of the acceleration and dynamic stress are reached about 50% on the subgrade surface.In the softening condition,the dynamic stress is slightly increased because the interface effect appears between the soft and hard interface,and it is different from the attenuation rules of the acceleration.The dynamic stress propagation on subgrade appears stress diffusion phenomenon that causes the dynamic stress amplitude on the lower part of the subgrade is larger than the upper.With the increase of the excited frequency,the acceleration attenuation is increased first and then decreased in the same depth,and reaches the maximum value at 19.1 Hz.The dynamic stress is increased gradually from the surface of subgrade 0.35 m,with the similar acceleration law under 0.35 m.