Abstract
This paper focuses on the reinforcement effect of full-face anchorage in thick soft rock roadway. A 2D semimodel of full-face anchorage in roadway with thick surrounding soft rock was proposed firstly by transforming the confinement effect of the excavation face in the longitudinal direction as the virtual internal support force at the circumferential surface. Then, based on the theory of elasticity, the theoretical model of the coupling effect between surrounding rock and anchoring system was established, and the analytical solutions of stress and displacement were obtained employing superposition principle. Finally, the theoretical solution was verified by numerical simulation, and the distribution laws of stress release-anchor stock-surrounding rock coupling were analyzed in detail considering stress release. Results demonstrated that the stress field of the surrounding rock diverse widely with different stress release coefficients. With the increasing of stress release coefficient, the radial stress of the surrounding rock decreases, while the tangential stress increases. The supporting role of the bolt is mainly reflected in improving the radial stress of the anchorage zone. However, it has little effect on the tangential stress. What is more, the anchoring effect is more significant to soft rock stress than hard rock. In addition, the prestress of rock bolt has a certain matching relation with the bolt parameters, the surrounding rock parameters, and the initial stress. This study laid a theoretical foundation for further analysis of the interaction between surrounding rock and bolt supporting in plastic zone.
Highlights
Introduction e Jurassic andCretaceous weakly cemented soft rocks widely exist in western China
By applying the node constraint, the node reaction force around the hole can be extracted, and the node reaction force acted as the virtual internal support, which is applied to the excavation boundary to simulate stress release. en, the virtual support force with different stress release coefficients can be obtained by MATLAB programming
Regardless of the value of the stress release coefficient, in the elastic range, it is always satisfied that σθ + σr 2p. e stress disturbance range of roadway excavation is about five times of the radius (5R), and the difference of stress release coefficient leads to obvious difference between radial stress and tangential stress distribution in 5R range. e tangential stress of surrounding rock is closely related to the damage degree, while the radial stress has the effect of confining pressure, which can restrain the failure of surrounding rock [31, 33]
Summary
Is paper focuses on the reinforcement effect of full-face anchorage in thick soft rock roadway. Most of the researches focus on the threedimensional simulation of the roadway construction process, analyze the stress and deformation law of surrounding rock and lining with construction, or through the numerical model to analyze the change of the radial virtual support force of the excavation surface based on the radial displacement release coefficient of roadway wall [20,21,22,23]. Erefore, some researchers established a two-dimensional model of roadway under certain conditions and resimulation of excavation by stress release rate control [26, 27] This simplified analysis methods must satisfy that the axial direction of the roadway which is one of the main stress directions. Δp pα − p∗, and the variation of the radial stress of the contact surface between the anchorage area and the nonanchorage area is
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