Performance of Sub-rectangular Tunnel Under Static and Dynamic Loading

Tunnel is an artificial underground passage built through a hill, road or river. Due to lack of space on the surface, it becomes essential to construct underground tunnels. To select a suitable type of tunnel section and its analysis are one of the important areas in geotechnical engineering. Sub-rectangular tunnels are ideal for underground projects such as subway entrance passages, underground pedestrian crossings, and so on. However, just a few researches have looked into sub-rectangular tunnels so far. In this paper, the performance of sub-rectangular tunnel under static as well as dynamic loading has been studied and results are compared with the twin-circular and rectangular tunnel in terms of crown settlement of tunnel sections. For this purpose, numerical analyses of different tunnel sections viz., twin-circular, rectangular and sub-rectangular tunnel were carried out using MIDAS GTS NX and by considering different soil conditions prevailing in India. Tunnel sections were analyzed by considering varying parameters such as overburden depth from top to the center of the tunnel and water table under static and dynamic loading. The performance of tunnel sections is then compared. It is found that sub-rectangular tunnel is found to be more effective for different analysis cases.