Geotechnical aspects of tunnel lining with segmental joint parameters to improve soil surface settlement prediction

Abstract

Conventional lining design usually considers tunnel lining as a uniform rigid ring model by implying high partial safety factor on the bending moment which is overestimated, due to inaccurate assumptions. To overcome this problem, investigation on the influence of joints on the behaviour of the global lining is significantly important especially when the interaction between segments is included. This paper presents investigation in tunnel segment joint influence on global tunnel lining behaviour especially when the interaction between segments becomes nonlinear, in different type of soil, so that more realistic soil-tunnel lining response can be obtained. The effect of segment joint parameters (linear or nonlinear) and soil parameters was investigated via numerical modelling. The predicted stress and displacement results from the numerical model were verified with the result obtained from field data collection. FEM model of original soil and settlement monitoring data depicted similar pattern of settlement but the FEM model did not captured the sudden settlement at the distance of 40 m from starting point. This was due to the simplification of FEM model and assumption of greenfield. The sand model gave similar result pattern like original case study soil behaviour. Clay model, in opposite, showed heaving at the beginning of construction that caused by the pressure induced by the weight of concrete and moving the water pressure toward the ground. One could conclude that, the elastic settlement profile occurred due to selected parameters of soil and Mohr Coulomb model.