公路隧道散体围岩中锚杆支护优化布置研究

Study on Optimal Arrangement of Bolt Supporting in Bulk Rock of Highway Tunnel

隧道系统锚杆和锁脚锚杆的优化布置能够减少初衬锚杆的数量,降低锚杆对围岩的扰动,节约建设成本。针对传统的系统锚杆支护方案提出了一种新型锁脚锚杆支护方案。以延崇高速某特长隧道为研究对象,借助FLAC3D有限差分软件对隧道支护进行数值模拟分析。对比传统锚杆支护与新型锁脚锚杆支护方案,在新型锁脚锚杆支护方案基础上提出两种增强支护方案。数值模拟计算结果表明,在散体围岩隧道200 m埋深情况下取消全环系统锚杆,采用新型锁脚锚杆支护,并在拱顶局部打设系统锚杆或加强超前小导管注浆的支护方案能够保证隧道围岩与衬砌结构的安全与稳定性。通过在隧道现场布置监控量测仪器,将实测数据与数值模拟计算结果相结合,对公路散体围岩隧道支护方案的优化具有指导意义。

The system optimization of tunnel systematic bolt and feet-lock bolt can reduce the disturbance to surrounding rock,reduce the number of bolt support in the initial lining of tunnel,and save the construction cost of tunnel.Aiming at the traditional systematic bolt support plan,a new type of feet-lock bolt support scheme is proposed.Taking a super long tunnel of Yanchong expressway as the background,the numerical simulation analysis of tunnel support is carried out with FLAC3D finite difference software.Compared with the conventional systematic bolt support and the new type feet-lock bolt support scheme,two other strengthening support schemes are put forward.The results of numerical simulation show that when the weak surrounding tunnel is buried in depth of 200 m,canceling the whole ring system bolt,adopting new type feet-lock bolt support,and setting up systematic bolt or strengthening advance small pipe grouting in the vault can ensure the safety and stability of tunnel surrounding rock and lining structure。By arranging monitoring and measuring instruments in the tunnel site,the measured data are combined with the numerical simulation results,and has guiding significance for the optimization of support scheme of highway tunnel in bulk rock.