Theoretical analyses of stress field in surrounding rocks of weakly consolidated tunnel in a high-humidity deep environment

Abstract

The present research aims to mitigate the hazard induced by the expansive deformation of tunnel surrounding rocks during deep coal mining in a high-humidity environment. Firstly, based on the theory of humidity stress field and elastoplastic theory, the governing differential equation of the mechanical response of surrounding rocks of a circular tunnel is established. Secondly, the present study takes the exponential-function-based humidity distribution as an example to derive the radius of the plastic zone of surrounding rocks and the theoretical formula for calculating the associated stress field. Also, a detailed analysis is conducted concerning the tunnel humidity, humidity affected area, effect of support resistance on plastic zone of surrounding rocks, and the evolution of stress field of surrounding rocks for various relative locations between the humidity affected area and the area disturbed by the excavation stress. Finally, the accuracy of the humidity distribution function and the calculation method of radius of the plastic zone were verified by field tests. Results indicate that under the interaction between humidity and excavation-induced disturbance, the plastic zone of surrounding rocks is expanded compared to that of the case without the influence of humidity. The evolution law of stress field is related to the distribution of humidity field and the relative position of the excavation stress disturbance zone. The quantitative relationship between plastic zone, stress field and humidity given in this paper has certain engineering reference value.