中英钻爆法铁路隧道设计方法比较研究

针对钻爆法铁路隧道围岩分级、初期支护及二次衬砌设计方法等内容,对比分析了中英两国在隧道设计方法和理念方面的差异。对比分析表明,英国隧道设计基于巴顿的Q系统,该系统用表征岩体的RQD值,节理组数、粗糙度系数、地下水折减系数、蚀变系数及地应力折减系数来反映围岩整体力学性质,英国铁路隧道初期支护采用经验设计法,根据Q图谱进行预设计,采用有限元程序进行检算。二次衬砌采用极限状态理论进行设计,衬砌承受围岩压力的标准值由巴顿公式计算得出,二次衬砌设计时不考虑初期支护的作用。中国铁路隧道初期支护多采用类比法进行设计,并采用有限元法进行校核,二次衬砌普遍按破损阶段法设计,围岩压力根据统计回归公式计算,采用安全系数K控制结构安全性。相比而言,英国隧道设计方法和理念与围岩参数联系较为紧密和直观,而中国隧道设计方法基于定性与定量结合的围岩分级标准,两者差异明显。

Comparative Research between China and Britain on Design Approach of Railway Tunnel with Drilling-and-Blasting-Method

Focusing on relevant contents of design approach of railway tunnel with drilling and blasting method,such as surrounding rock classification,primary support and secondary lining and so on,this research compared and analyzed the difference between China and Britain on tunnel design approach and design idea. The result of comparative analysis indicates:( a) The tunnel design in Britain is based on the Q system of Barton,which characterizes the overall mechanical property of surrounding rocks by using rock mass' s RQD value,joint sets,roughness coefficient,underground-water reduction coefficient, alteration coefficient and ground-stress reduction coefficient. In Britain,the primary supports of railway tunnels are designed by empirical method: the Q pattern is employed for preliminary design,followed by finite element program to do check calculation. Also in Britain,the secondary linings are designed by limit state design theory,and the standard value of surrounding rock pressures acting on linings are calculated from the Barton formula,without considering the effect of primary support.( b) In China, most of the primary supports of railway tunnels are designed using analogy method,followed by finite element program to do check calculation. The secondary linings are designed according to plastic stage method; rock pressures are calculated according to the statistic regression formula, and the comprehensive safety factor K is adopted to control the structural safety.(c) By comparison,the British tunnel design approach and design idea are more closely linked with the surrounding rock parameters and easy to understand,while the Chinese tunnel design approach is based on a combination of qualitative and quantitative rock classification standard; and the difference between the two is obvious.