锚固上覆红黏土岩体边坡的地震动力响应

Dynamic response of anchoring overlying red clay rock slope under earthquake action

基于云南省S214思茅-江城二级公路某一边坡,利用有限差分软件FLAC3D中动力分析模块,研究了地震作用下锚杆支护的上覆红黏土岩体边坡的动力响应。基于土体与支护结构相互作用及其协同工作,建立了三维有限差分模型,给出了阻尼和动力作用下边界的选取方法,分析了地震作用下锚杆支护上覆红黏土岩体边坡的动力响应规律,研究了在地震作用下锚杆支护边坡的抗震效果。结果表明:地震作用后各层锚杆轴力和砂浆的剪应力都有所增大,但每层锚杆轴力的增幅都各不相同,锚杆轴力沿全长分布不均匀,且各层锚杆轴力均在红黏土与基岩的交界处最大,剪应力则表现为整体增大的趋势而且最大值向坡面靠近,地震作用前、后剪应力的最小值都是在红黏土与基岩的交界处;地震作用下锚杆的支护很好地限制了边坡的变形,加大了边坡的延性,具有很好的抗震性能;边坡在地震作用下产生了永久位移;坡体内加速度在竖向随高程增加而增大;平台的设置削弱了坡面加速度的增大趋势,起到了一定减震作用。研究结论对锚杆支护边坡的抗震设计与动力分析有一定参考价值。

Based on a slope located at the S214 Simao-Jiangcheng second class highway, the dynamic module of finite difference software FLAC3D is used to study the dynamic response of bolting shallow red clay slope under seismic loading. Based on the interaction and coordination of ground and supporting structure, a three-dimensional finite difference model which takes the damping and dynamic boundary into consideration is established. The dynamic response pattern of shallow red clay slope and the supporting effect of bolt under earthquake are analyzed. It is found that both the bolt axial force of each layer and the shear stress in mortar increase during earthquake. However, with variant increment in each layer of bolt axial force and uneven distribution along length direction, the axial force reaches maximum value at the junction of soil and bedrock. While the shear stress shows an overall increasing trend;and its peak value position approaches the slope surface. The minimum value positions of shear stress before and after earthquake are both located at the junction of soil and bedrock. Anchors’ support outstandingly constrains the deformation of slope and increases the ductility of ground under earthquake, which renders good aseismic behavior. Moreover, permanent displacement of slope is generated after the earthquake; and the seismic acceleration inside the slope increases with the raise of vertical elevation. While the platform setting weakens the increasing trend of slope surface acceleration, contributes in alleviating seismic effects. The research has certain reference value for seismic design and dynamic analysis of slope supported by anchor bolts.