超大断面铁路隧道施工断面综合荷载释放过程研究

Study of construction section comprehensive load releasing process of ultra-large section railway tunnel

隧道开挖扰动会使影响范围内的围岩发生松弛,同时还产生一定的荷载作用于隧道结构。而在隧道开挖面推进时,作用于隧道结构上的荷载在应力调整过程中不断释放,最终在隧道结构及围岩达到稳定状态后荷载释放过程同时结束。通过数值分析及模型试验,对超大断面铁路隧道施时的隧道断面整体荷载释放过程进行了相关研究。研究了台阶法开挖过程中隧道洞壁不同特征点的荷载变化规律,并定义了能够表征隧道施工过程断面整体荷载释放状态的断面综合荷载释放率和荷载释放差异系数的概念,通过两者对隧道开挖断面整体荷载释放状态进行分析总结。在随后进行的隧道施工过程地质力学模型试验中,通过对开挖面推进洞壁不同位置围岩径向压力的变化规律进行监测,证明了数值模拟得到的结论,并进一步说明在隧道开挖的荷载释放过程研究中,应将整个断面作为研究对象,分析断面整体荷载释放状态,才能对隧道施工中的荷载释放过程有一个更加全面的认识。

Tunnel excavation will lead to surrounding rock loose and exert certain load on the structure in the meantime.In the excavation process,the load of structure releases continuously in the stress adjustment process till the structure and rock mass stabilizing.Numerical analysis and model test are carried out to research the load releasing process of the whole section in the construction of ultra-large section railway tunnel.The load fluctuation rules of key points in bench excavation are studied firstly,then concepts of section comprehensive load release rate and difference coefficient of load release that characterizes the state of load release of the whole section are defined;and the load fluctuation rules in the process of construction are summarized via the two parameters.With monitoring of change laws of radial pressure at key points of rock mass in the geomechanical model test,the conclusions obtained by numerical analysis are testified;and the principle that the section must be regarded as a whole is realized to make the study of load release more comprehensive.