Adaptive constitutive soil modeling concept in mechanized tunneling simulation

This paper proposes an innovative concept of adaptive constitutive soil modeling to optimize the complexity of the numerical simulation of shield tunneling. This concept involves the use of an adequate constitutive model for soil, in accordance with mechanical incidents in the domain, to reduce the number of complex soil parameters and computational costs, focusing on the accuracy of numerical predictions. In such an approach, adequate soil investigation can be scheduled by designing a limited number of sophisticated laboratory tests at certain locations, while the rest of the domain can be explored with basic conventional laboratory tests to identify ordinary soil parameters. This concept leads to obtaining adequate and dominant soil parameters at each depth to accurately simulate the phenomenological aspects of soil behavior and soil-tunnel boring machine (TBM)-tunnel interactions without inducing inadmissible uncertainty in terms of advanced soil parameters for unaffected zones. The numerical model accounts for such constructional components face support, grouting in the annular gap, and lining installation. The numerical model responses are studied through the investigation of the evolution of the ground subsidence, as well as soil stresses and lining forces. The behavior of the soil is assumed to be described by a family of hierarchical elastic-plastic constitutive models based on Mohr-Coulomb failure theory. In addition, the size of the target zone where the model adaption should be conducted is studied while its influences on model responses are addressed. Finally, the contribution of the proposed solution to reduce the uncertainty of the numerical predictions is evaluated.