Abstract:

Tunneling in urban areas is growing in response to the increased needs for efficient transportation, many urban tunnels are constructed in soft ground at shallow depths. The construction of tunnels in urban areas may cause ground displacement which distort and damage overlying buildings. In the past fewdecades, tunnel boring machines have been used to drill in increasingly difficult geotechnical conditions such as soft ground like soft clay. This is particularly true for mechanised tunnelling and specific boring machines, as, for examples, the compressed air shield, the earth pressure balanced shield and the slurry shield, have been developed in the recent decades for managing the instability of the excavation profile in unfavourable geotechnical and hydrogeological conditions, with challenge external constraints. The stability of the face is one of the most important factors in selecting the adequate method of excavation of a tunnel. This face pressure is a critical paramater because the varying pressure can lead to the total failure and collapse of the face. In this paper aims to offer a guide to the methods for tunnel face stability assessment in mechanised tunnelling and used analytical calculation methods to determine the minimum tunnel face pressure are either based on the limit equilibrium methods