动荷载作用下边坡锚固系统合理设计探讨

Discuss on Reasonable Design of Slope Anchor System under Dynamic Loads

爆破、地震或列车振动等动荷载作用下,边坡锚固系统易产生锚筋松弛、夹具损伤、注浆体拉裂及界面粘结失效等情况,影响其预应力赋存状态、加固效果和耐久性。基于动荷载作用类型和锚固系统动力响应特征分析,提出了动载下不同地层内的锚固段合理结构设计方案和锚筋抗拉安全系数及锁定荷载的建议。动载下自由段(外锚固段)宜设计为全粘结型或增设多级反锚装置,形成岩土自锁锚固,以控制预应力损失和防止锚头或自由段破断造成突发性灾害;在水泥基灌浆体中掺入钢纤维或树脂纤维,可改善锚固体抗裂性能,提高其抗疲劳和抗冲击能力;建议优先采用防腐性能卓越的填充型环氧涂层钢绞线,以提高锚固体在动载破裂时的耐久性。

Under dynamic loads （such as blast, earthquake and train vibration）, some adverse effects are produced on the slope anchor system including anchor bar relaxations, fixture damage, grout ripping and interface debonding, which can influence the occurrence of prestress, the reinforced impact and the durability of slope anchor system. Therefore based on the dynamic loads types and analysis on characteristics of dynamic response, the reasonable structure design of inner-anchoring section within different stratum under dynamic loads is given. Safety factor of anchor bar and loads locking way are also presented in this paper. Under dynamic loads, the free section should be designed to be full grouted or added additional multistage reverse anchoring set, so that the auto-lock anchorage comes into being in order to control the prestressing loss and prevent the anchorage （or free section） from rupture or avoid unexpected calamities. By adding steel fibre（or resins fibre） into cement grouting material, the cracking, fatigue and punching resistance capability of bolt-grouting body can be improved. And it is suggested that the epoxy coating steel strand cables of filled type should be adopted preferentially because of their good anti-corrosion performance. It can improve the durability of bolt-grouting body under dynamic loads.