Abstract
The viewpoint that the ground initial elastic displacement and the interaction between the ground response curve (GRC) and support response curve (SRC) in the surrounding rock should be considered at the same time in the mechanical analysis of the circular tunnel is proposed, and its solution method is also established. Meanwhile, in order to consider the effect of the intermediate principle stress, Drucker-Prager criterion is introduced to describe the yield property of the surrounding rock. The calculation example indicates that the final radial displacement of the tunnel circumference will increase when the ground initial elastic displacement in the surrounding rock is considered before the support structure is applied, which indicates that it is necessary to consider the ground initial elastic displacement in the surrounding rock before the support structure is applied. With increasing the support resistance force and the initial field stress, the plastic zone radius in the surrounding rock and the radial displacement of the tunnel circumference will decrease and increase, respectively, while with increasing the rock internal friction angle and cohesion, the plastic zone radius in the surrounding rock and the radial displacement of the tunnel circumference both decrease. Meanwhile, with the stress Lode parameter increasing from −1 to 1, the plastic zone radius in the surrounding rock and the radial displacement of the tunnel circumference both greatly decrease and then slightly increase. It indicates that the intermediate principle stress has some effect on the calculation results.
Highlights
Many researches have been done on the tunnel engineering [1,2,3,4,5,6], of which the deformation and stress responses of the ground caused by tunnel excavation and the interaction with the support structure are the theoretical basis for guiding the design of tunnel excavation and support [4,5,6]
Li et al [4] investigated the undrained responses for deep circular tunnels with reinforcement in saturated ground analytically and found that, with the decrease of internal support pressure, the plastic zone may firstly appear in the reinforced ground or in the natural ground, and in the two zones simultaneously
Zou et al [6] investigate a new procedure for the ground response curve (GRC) in strain-softening surrounding rock for a circular opening
Summary
Many researches have been done on the tunnel engineering [1,2,3,4,5,6], of which the deformation and stress responses of the ground caused by tunnel excavation and the interaction with the support structure are the theoretical basis for guiding the design of tunnel excavation and support [4,5,6]. On the condition that the rock elastoplastic model is adopted to study the plastic zone in the surrounding rock, it is assumed that the strength of the surrounding rock can be fully activated to reduce the support workload when the intermediate principal stress is taken into account. Nearly none of the existing researches consider this issue Based on this viewpoint, we make a profound study on the ground stress response in the tunnel surrounding rock. D In order to study the effect of the intermediate principal stress on the ground stress response and plastic zone in the tunnel surrounding rock, Drucker-Prager criterion is adopted as the yield criterion of rock strength. Based on the actual construction process of the tunnel, we put forward the stress analysis method of the underground circular tunnel considering the interaction between GRC and SRC, which can provide a reference for other engineering projects
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