Study on hydromechanical damage coupled model of Boom clay during tunnel excavation and construction

Abstract

Based on the theory of continuum damage mechanics, a modified Mohr–Coulomb failure criterion according to plastic damage evolution and the hydromechanical coupling is applied to analyse the excavation damage of Boom clay influenced by the evolution of pore pressure and plastic strain. Considering the actual case of construction of the connecting gallery of radioactive waste disposal in the deep Boom clay formation in Belgium, a nonlinear finite element damage model for simulating shield tunnelling is proposed to study the evolution of damage, pore pressure and permeability of the surrounding rock. The variations of damage and permeability around the tunnel with time are analysed in detail. The proposed model is able to effectively depict the main features of hydromechanical behaviours of Boom clay. Therefore, the present model can provide references for the distribution, degree and evolution of damage and fractures self‐sealing process analysis of surrounding rock.

Keywords:

• Boom clay
• Hydromechanical coupling
• Damage evolution
• Permeability
• Finite element method

This research work is financially supported by the National Natural Science Foundation of China (grant no. 50720135906), Educational Commission of Hubei Province (grant no. Q20101301) and the National Science Foundation for Post‐doctoral Scientists of China (grant no. 20100471516).