特大跨度小净距隧道中间岩柱可靠度分析及其加固处理措施

魁岐2号隧道位于福卅I国际机场高速公路二期工程A3标段，隧道跨度达到19．9m，中间岩柱最小净距为11．7m，为国内首座双向八车道小净距隧道工程。针对魁岐2号隧道工程的特殊性，利用离散单元法对节理岩体中特大断面小净距隧道的受力情况进行了分析，根据可靠度理论，通过对魁岐2号特大断面小净距隧道中间岩柱的可靠性分析发现，对于特大断面小净距隧道，中间岩柱最薄弱的部位主要集中在岩柱上部，因此，埘于特大断面小净距隧道施工过程中宜重点对岩柱上部进行加固处理。同时，根据不同围岩级别中中间岩柱的可靠度值显示，魁岐2号特大断面小净距隧道的净距取值基本上是合理的，整体上二能满足稳定性的要求。

Reliability Analysis on Middle Rock Pillar in Small Clear Space Tunnels with Super Span and the Reinforcement Measures

Kuiqi No. 2 tunnel is belonged to tender section A3 of the phase II project of Fuzhou International Airport High- way. It is the first small clear space tunnel project for 8 lanes in China with the span of 19.9 meters and with the middle rock pillar of minimum clear distance about 11.7 meters. According to the specialty of Kuiqi No. 2 tunnel and based on dis- crete element method, some numerical simulation analysis is conducted to analyze the initial surrounding rock stress to the tunnel. The results show that the worst position of mechanical state in large-section tunnel is in the upper portion of middle rock pillar in weak surrounding rock, so special reinforcement measures should be used there. According to the reliability value of middle rock pillar in different rock mass, the net distance between Kuiqi No. 2 small clear space tunnels with super span is reasonable to satisfy the stability requirement.