大跨度隧道预应力锚固体系协同承载的压力拱效应  

Pressure Arch Effect of the Synergetic Bearing of Pre-stressed Anchorage System in Large-span Tunnel

作　　者：孙振宇[1] 皇甫楠琦 张顶立[1] 李沐阳 王嘉琛 SUN Zhenyu;HUANGFU Nanqi;ZHANG Dingli;LI Muyang;WANG Jiachen(Key Laboratory for Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学城市地下工程教育部重点实验室,北京100044

出　　处：《铁道标准设计》2023年第1期10-16,24,共8页Railway Standard Design

基　　金：国家自然科学基金项目(51738002)。

摘　　要：为研究大跨隧道锚固体系的协同承载机理,以压力拱效应为量化指标进行分析,根据围岩开挖应力分布特征,设置无支护开挖、单一预应力锚杆支护、预应力锚固体系联合支护3种工况,研究不同围岩条件在各工况作用下的压力拱动态演化机制。研究结果表明:压力拱位置和厚度均受围岩条件影响,围岩条件越差,压力拱位置距隧道边界越远且厚度越大,不利于围岩稳定性控制;压力拱成拱系数变化趋势与切向应力一致,呈先增大后减小趋势,且切应力集中区域成拱系数大于1;预应力锚固体系作用下压力拱向隧道边界处移动,可有效控制围岩压力拱的继续发展,使压力拱更快达到稳定,并减小压力拱范围,优化压力拱形态,使其趋于“圆拱形”;预应力锚固体系对于围岩压力拱的影响效果优于单一锚杆支护,尤其是当围岩条件较差时,其协同承载效应更为显著。Aiming at the synergetic bearing mechanism of the anchorage system in large-span tunnels, the pressure arch effect is taken as a quantitative index for analysis. The dynamic evolution mechanism of the pressure arch under different surrounding rock conditions is studied according to the stress distribution characteristics of surrounding rock with the setting of three working conditions of excavation without support, single pre-stressed bolt support and combined pre-stressed anchorage system. The results show that both the position and thickness of the pressure arch are affected by surrounding rock conditions. The worse the surrounding rock conditions are, the farther the position of pressure arch is from the tunnel boundary and the thicker the arch is, which is not conducive to the stability control of surrounding rock. The variation trend of arch forming coefficient of pressure arch is consistent with that of tangential stress, which increases first and then decreases, and the arch forming coefficient of shear stress concentration area is greater than 1. The pressure arch moves to the tunnel boundary under the action of pre-stressed anchorage system, which can effectively prevent the pressure arch from continuing development, and stabilize the pressure arch more quickly. Thereafter, the scope of the pressure arch is reduced and the pressure arch tends to be a “circular arch”. The effect of pre-stressed anchorage system on the pressure arch effect is superior to that of the single bolt support, especially when the surrounding rock is unfavorable, and the synergistic bearing effect becomes more significant.

关 键 词：大跨度隧道 预应力锚固体系 协同作用 压力拱 协同承载 

分 类 号：U455.71[建筑科学—桥梁与隧道工程] TV554[交通运输工程—道路与铁道工程]