3-D numerical model of jack force interaction to segmental tunnel lining in soft soil

Abstract

The construction process of a bored tunnel is a complicated process. During tunnelling, loads were acting on tunnel and tunnel lining were installed to support excavation. Simultaneously, soil redistribution induced by tunnel excavation leads to lining to deform. One of the parameters that affect global soil-tunnel behaviour is the jack forces. Jack force is exerted during the tunnel advancement to install the lining and the same time to enhance tunnel face stability. The complexity of jack force application to ensure the overall tunnel stability is not fully studied yet. Hence, the impact of jacking force on segmental tunnel lining and surrounding soil during the tunnel advance is still unclear. This paper presents a numerical simulation by using ABAQUS/Standard 3D FE software to determine and investigate the lining deformations/jacking force relationship. The behaviour of different tunnel lining thickness applied with a variation of jack forces in the tunnel-boring machine (TBM) were examined. The result based on the numerical model explained that the jacking force required to advance is related to the cross section area of segments. Finally, a relation has been established between the segment's thickness and the jacking force t hat required advancing through a certain soil block with specific loads cases. The findings showed that the complex geological features and loads case applied to cause great stress on the tunnel face which have to be encountered by a certain thrust magnitude to advance the tunnel. The model analyses the contact reaction and radial reaction to the segment as a result of the axial force that is exerted by jack thrust and bending moment due to strata load, respectively. However, a proposed model that suggests a certain step to investigate and analyse the magnitude of jack forces is required.