Khan Babar, Jamil S Muhammad, Jafri Turab H, Akhtar Kamran
NUST Institute of Civil Engineering, National University of Science and Technology (NUST), Islamabad, Pakistan.
Military College of Engineering (MCE), National University of Science and Technology (NUST), Islamabad, Pakistan.
Heliyon. 2019 Dec 18;5(12):e02944. doi: 10.1016/j.heliyon.2019.e02944. eCollection 2019 Dec.
Empirical based approaches play an important role in tunnel excavation and support system design. These approaches are considered to be very effective in optimising the process of tunnel excavation and particularly tunnel widening. Several reliable empirical approaches have been developed, however the selection or utilisation of an appropriate empirical method for designing the widening of a tunnel is still a challenging task. Therefore, in this work, the analysis of seven different empirical design approaches was carried out to determine the rock mass behaviour during tunnel widening in high in-situ stress state. These approaches include New Austrian Tunnelling Method, Rock Mass Rating, Rock Mass Quality, Rock Mass Index, Rock Structure Rating, Geological Strength Index and Basic Quality Index. On the basis of simulated statistical results obtained from the said empirical approaches, it was found that the application of Rock Mass Quality approach is highly effective in the tunnel widening since it can satisfactorily incorporate the equivalent dimensions and in-situ stress condition of widened tunnel. The method furnishes optimised reinforcement and support design. Additionally, this study also produces reliable data related to the initial excavation of tunnel which can be helpful in defining precise rock mass parameters during tunnel widening.
基于经验的方法在隧道开挖和支护系统设计中起着重要作用。这些方法被认为在优化隧道开挖过程，特别是隧道扩挖过程中非常有效。已经开发了几种可靠的经验方法，然而，选择或运用合适的经验方法来设计隧道扩挖仍然是一项具有挑战性的任务。因此，在这项工作中，对七种不同的经验设计方法进行了分析，以确定高地应力状态下隧道扩挖过程中的岩体行为。这些方法包括新奥地利隧道施工法、岩体质量指标、岩体质量、岩体指数、岩石结构评级、地质强度指标和基本质量指标。根据从上述经验方法获得的模拟统计结果，发现岩体质量方法在隧道扩挖中应用非常有效，因为它可以令人满意地纳入扩挖隧道的等效尺寸和地应力条件。该方法提供了优化的加固和支护设计。此外，本研究还产生了与隧道初始开挖相关的可靠数据，这有助于在隧道扩挖过程中定义精确的岩体参数。
