循环荷载作用下土拱效应的离散元研究

基于室内Trapdoor模型试验,采用PFC2D研究了循环荷载作用下不同路堤高度的土拱效应,从力链和位移的角度对路堤内土拱结构、填料移动的变化规律进行了宏观和微观分析。结果表明:抗扭转模型可以较好地模拟以铝棒相似土作为填料的Trapdoor试验; 在循环荷载作用下路堤内形成的土拱结构发生破坏,土拱效应得到削弱,土拱结构的破坏主要发生在初始加载阶段,并且在这个阶段高路堤底部土拱结构比低路堤受到外部荷载的影响要小; 随着加载的进行,路堤内部形成了新的稳定受力结构并基本保持不变; 在循环加载过程中低路堤加载板两侧的力链结构受到的影响和扰动比高路堤的大; 在循环荷载作用下,路堤表面发生了沉降,其中塑性位移主要发生在初始加载阶段,之后产生的几乎是弹性位移; 高路堤加载板两侧土体相较于低路堤在第一次加载时更不容易产生横向位移被挤向两端,加载板的竖向位移减少,从而减少加载板对底部土体的影响,使得路堤底部的土拱结构更不容易被影响。

Discrete element analysis of soil arching effect under cyclic loading

Based on indoor Trapdoor model test, PFC2D was used to study the soil arching effect of different embankment heights under cyclic loading. The changes in soil arch structure and filler movement inside the embankment were analyzed from the perspectives of force chain and displacement, and macro and micro analyses were conducted. The results show that the anti torsion model can effectively simulate the Trapdoor test using aluminum rod like soil as filler. Under cyclic loading, the soil arch structure formed within the embankment is damaged, and the soil arching effect is weakened. The failure of the soil arch structure mainly occurs during the initial loading stage, and at this stage, the bottom soil arch structure of the high embankment is less affected by external loads than that of the low embankment. As the loading progresses, a new stable stress structure is formed inside the embankment and remains basically unchanged. During the cyclic loading process, the force chain structure on both sides of the low embankment loading plate is more affected and disturbed than that of the high embankment. Under cyclic loading, the surface of the embankment undergoes settlement, with plastic displacement mainly occurring during the initial loading stage and almost elastic displacement occurring thereafter. Compared to low embankments, the soil on both sides of the loading plate on high embankments is less prone to lateral displacement and being squeezed towards both ends during the first loading. The vertical displacement of the loading plate is reduced, thereby reducing the impact of the loading plate on the bottom soil and making the soil arch structure at the bottom of the embankment less susceptible to be impacted.