Interaction analysis between composite supports and rheological rock considering progressive hardening characteristic of shotcrete: Fid-Bau Portal

Interaction analysis between composite supports and rheological rock considering progressive hardening characteristic of shotcrete

Liu, Chang / Zhang, Dingli / Zhang, Sulei / Sun, Zhenyu

Abstract

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Highlights • A model is proposed to study interaction between supports and rheological rock. • Impact of shotcrete hardening feature on tunnel mechanical response is identified. • Effect of rock rheological behavior on shotcrete mechanical behavior is examined. • Supporting time of secondary lining in rheological rock is recommended.

Abstract The shotcrete stiffness varies over time in the hardening period, which complexes the interaction between support structures and rheological rock. This study presents an analytical approach to examine the time-dependent interaction between support structures and rheological rock of a deep-buried tunnel, where shotcrete progressive hardening feature, tunnel excavation effect, and sequential installation of linings are considered. The time-dependent stiffness and fictitious support pressure are introduced to qualify hardening process of shotcrete and spatial effect of tunnel excavation. The Generalized Kelvin and Burgers models are adopted to represent two different rheology behaviors of surrounding rock. Results show that shotcrete hardening characteristics and excavation speed significantly influence tunnel convergence and support pressure. Ignoring shotcrete hardening characteristic leads to underestimating tunnel convergence and pressure of secondary lining, but overestimating pressure borne by shotcrete. Furthermore, mechanical response of two different types of primary support is investigated and the supporting time of the secondary lining is recommended. Investigations show that secondary lining should be applied suitably to bear subsequent rheological load when tunneling in surrounding rock with a notable rheological effect. Finally, the proposed analytical model is applied to tunnel engineering to prove its applicability. The main contribution of this work to literature is establishing an approach to identify hardening characteristics of shotcrete on interaction mechanism between support structures and rheological rock.