Abstract
Through theoretical calculation, the stress and deformation of surrounding rock can be analyzed, providing guidance for the support design and optimization of soft rock roadways. In this paper, theoretical solutions for both the optimal support pressure and the allowable maximum displacement of surrounding rock are derived from the Drucker–Prager (DP) yield criteria and the steady creep criterion expressed by the third invariant of deviator stress. The DP criterion with different parameters is compared and analyzed with an engineering example. Then, based on the calculation results the effects of long-term strength, cohesion, and internal friction angle of soft rock on the maximum plastic zone radius and allowable maximum displacement of roadway are discussed. The results show that the optimal support solution of soft rock roadways based on the DP criteria can not only reasonably reflect the intermediate principal stress but can also be used to compare and discuss the influence of different DP criteria on the calculation results. The higher the long-term strength of the rock surrounding a roadway is, the smaller the optimal support force is and the larger the allowable maximum displacement is. When the calculated long-term strength of soft rock can ensure that the deformation of the roadway does not exceed the allowable maximum displacement, the roadway can maintain long-term stability without support. With an increase in the cohesion or internal friction angle of soft rock, the radius of the plastic zone decreases gradually and the allowable maximum displacement is reduced by degrees. The use of grouting and other means to improve the strength of surrounding rock can effectively reduce the roadway deformation and save support costs. This new theoretical solution can consider different intermediate principal stress effects and different DP strength criteria, enabling the parameters to become easier to determine. It has a wider range of applications, and the calculation results better demonstrate the strength potential of the surrounding rock.
Highlights
Academic Editors: Diyuan Li, Zhenyu Han, Xin Cai, Shijie Xie and School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China; Shandong Gold Mining (Laizhou) Limited Company Jiaojia Gold Deposit, Laizhou 261400, China
It can be seen that the optimal support force, the maximum radius of the plastic zone, and allowable maximum displacement calculated by different DP criteria are different
The DP strength criterion fully considers the influence of third invariant of deviatoric stress, the theoretical solutions of optimal support pressure intermediate principal stress, and the calculation results can better demonstrate the and allowable maximum displacement of surrounding rock are derived
Summary
Rock roadways exist widely in underground spaces, such as mining engineering, civil engineering, and tunnel engineering works. The existing optimal support solutions for soft rock roadways have not discussed the differences in DP criteria [25,26,27]. Based on DP series criteria reflecting intermediate principal stress, this paper deduces the analytical solution of optimal support force and the allowable maximum displacement of surrounding rock in a circular roadway. In doing so, it compares different DP criteria by an engineering example and discusses the effects of long-term strength, cohesion, and internal friction angle of soft rock on the maximum plastic zone radius and allowable maximum displacement of a roadway. The research results can provide theoretical guidance for the rational design and optimization of soft rock roadway supports
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
