Mixed empirical-numerical method for investigating tunnelling effects on structures

Abstract

© 2017 Elsevier Ltd The assessment of potential for building damage due to ground displacements caused by tunnelling is a global issue being faced by engineers. There is a two-way interaction between tunnelling and existing buildings; tunnel construction affects a building by inducing displacements in the soil underlying its foundation, and buildings influence tunnelling induced displacements via their weight and stiffness. Numerical analyses are widely used to investigate tunnelling and its impact on structures, however numerically predicted ground displacements are generally wider and shallower than those observed in practice. This paper presents a two-stage mixed empirical-numerical technique to estimate the effect of building stiffness on ground displacements due to tunnelling. In the first stage, greenfield soil displacements are applied to the soil model and the nodal reaction forces are recorded. In the second stage, the effect of tunnelling on a structure is evaluated by applying the recorded nodal reactions to an undeformed mesh. Results from conventional numerical analyses of the problem are compared against those obtained using the mixed empirical-numerical approach. Results demonstrate the importance of imposing realistic inputs of greenfield displacements when evaluating structural response to tunnelling.