An analysis of the support loads on composite lining of deep-buried tunnels based on the Hoek-Brown strength criterion

The composite lining load of a deep-buried tunnel is one of the key problems in tunnel support design. This study establishes four support cases to discuss the loads on primary support and secondary lining. A support load solution method is proposed based on the Hoek-Brown strength criterion by considering the stress release coefficient and the distal positions of bolts. According to engineering measurement, the displacements and loads of support structure calculated by elastoplastic theory are consistent with field measurement and numerical simulation which verifies the reliability of the theoretical method and studies the influence of support parameters on support load and bearing ratio. Results show that GSI, support time and support thickness have a great impact on support load, among which the combination of several factors may lead to the change of the main bearing structure. The higher the surrounding rock grade is, the higher the secondary lining bearing ratio will be. The support bearing ratio based on the Hoek-Brown strength criterion is consistent with field monitoring. The theoretical work done in this research can provide suggestions for engineering practice.