浅埋海底隧道的围岩应力解析解

Analytic solution on the stress of surrounding rocks for shallow subsea tunnel

海底隧道属于浅埋隧道,较之普通隧道水源补给无限,水的作用对海底隧道围岩应力场的影响不可忽略。基于Verruijt提供浅埋隧道求解基本方法,同时考虑自重及水的作用,将海底隧道问题分解为四部分进行求解。根据求得的浅埋海底隧道的围岩总应力场,考虑海底隧道开挖的短期和长期效应,分别得到了海底隧道开挖后短期、长期有效应力。基于该解析解研究水的作用对海底隧道围岩应力场的影响,结果显示:(1)考虑水的作用洞周环向有效应力较不考虑水有了较大提升,长期效应由于超静孔压的消散较短期效应洞周环向有效应力显著增长;(2)围岩最易发生破坏的位置是拱腰位置,而水的作用使得隧道洞周较不考虑水更易破坏;(3)不管长期效应还是短期效应,水深越大整个隧道的洞周环向有效应力越大。

The subsea tunnels can be regarded as shallow tunnels. As there is unlimited supply of water in subsea tunnel problem compared with common tunnel, the influence of water on surrounding rock stress cannot be neglected. Based on the solving method proposed by Verruijt, the problem of shallow subsea tunnel is divided into four parts to solve considering water effect and deadweight. Two stages in the tunnel construction process are considered when the effective stress is calculated: short term, immediately after construction; and long term, long after construction. The influence of water on the stress of surrounding rocks for shallow subsea tunnel is studied using the analytic solution. Result shows that:(1)Because of the water effect, there is larger circumferential effective stress around the tunnel than the stress with no water, and as the excess pore pressure dissipation occurs, the circumferential effective stress in long term has significant growth compared with short term;(2)The most possible position of surrounding rock failure in tunnel engineering is hance. Surrounding rock with water may fails more easily than that with no water;(3)Circumferential effective stress around the tunnel becomes larger as the water depth increases, whatever in short term or long term.