Because of high space utilization, elliptical cross-section sometimes is adopted in the design of urban pedestrian underpasses, underground common ditches and subway tunnels. Nevertheless, theoretical models on the blowout failure analysis of shallow elliptical tunnel faces are quite rare. Within the framework of the kinematical approach of limit analysis, deterministic and probabilistic blowout analyses of a shallow elliptical tunnel in frictional-cohesive soils are performed in this study. With the help of the spatial discretization technique, an improved blowout failure mechanism for shallow elliptical tunnel faces is generated. Compared with previous analytical or semi-analytical ones, such an improved failure mechanism allows variable frictional angles of soils to be readily accounted for. The critical blowout face pressure is determined based on the work rate balance equation and a hybrid global optimization algorism. The deterministic model is validated by numerical simulations, existing experimental results and theoretical solutions, in which the effect of the geometrical parameter of elliptical tunnel faces and the less computational cost over numerical simulations are emphasized. Deterministic parametric analyses are conducted to investigate the influences of several significant parameters in the form of charts. Probabilistic blowout analyses of tunnel faces excavated in spatially rotated anisotropy varying soils are then conducted via a combination of the subset simulation, the random field theory and the Markov Chain Monte Carlo method, and the influence of characteristic parameters of the random field are examined. In the end, a case study is presented to demonstrate the practical use of the proposed model.

由于空间利用率高，在城市人行地下通道、地下公共沟渠和地铁隧道的设计中，有时会采用椭圆形截面。然而，浅椭圆隧道掌子面井喷破坏分析的理论模型却很少见。在极限分析的运动学方法的框架内，本研究对摩擦粘性土中的浅椭圆隧道进行了确定性和概率性爆破分析。借助空间离散化技术，生成了一种改进的浅椭圆隧道掌子面井喷破坏机制。与以前的分析或半分析相比，这种改进的失效机制可以很容易地解释土壤的可变摩擦角。临界井喷工作面压力是根据工作率平衡方程和混合全局优化算法确定的。确定性模型通过数值模拟、现有实验结果和理论解决方案得到验证，其中强调了椭圆形隧道掌子面几何参数的影响和比数值模拟更少的计算成本。进行确定性参数分析以研究图表形式的几个重要参数的影响。结合子集模拟、随机场理论和马尔可夫链蒙特卡罗方法，对空间旋转各向异性变土开挖掌子面进行概率爆破分析，考察随机场特征参数的影响。