A probabilistic method to analyze collapse failure of shallow rectangular tunnels

It is difficult to forecast the collapse failure of rectangular tunnel roof because mechanical properties of surrounding rocks or soils are strongly affected by uncertainties. A uniform design (UD)-based response surface method (RSM) is proposed to handle uncertainties and to forecast the stability of rectangular tunnel roof with the help of Tunnel Seismic Prediction 203 plus (TSP203PLUS). Firstly, the influence factors of shallow rectangular tunnels are studied by the excavation half-width (Lu), which is derived using Mohr envelope. Since TSP203PLUS is an essential approach to predict the geohazard in tunnels, and a series of parameters such as the density (ρ), P-wave seismic velocity (V) and dynamic Young's Modulus (E) of geomaterials can be read from TSPwin (the software of TSP203PLUS). Then, the relationship among Lu and ρ, V and E are established, so that ρ, V and E read from TSPwin are treated as input variables in the UD-based RSM. Finally, a tunnel located in China is illustrated to demonstrate the efficiency of this approach and the result obtained from the proposed method is validated by Monte Carlo simulations (MCS). The proposed method provides a quick and effective method to study the collapse failure of rectangular tunnel roofs.