Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass

Abstract

To control the large deformation that occurs in deep shaft-surrounding rock, the post-peak strain-softening characteristics of deep jointed rock mass are discussed in detail. An equivalent post-peak strain-softening model of jointed rock mass is established based on continuum theory and the geological strength index surrounding rock grading system, and numerical simulations are performed using FLAC3D software. The convergence-constraint method is used to analyze the rock support structure interaction mechanism. A composiste support technique is proposed in combination with actual field breakage conditions. During the initial support stage, high-strength anchors are used to release the rock stress, and high-stiffness secondary support is provided by well rings and poured concrete. This support technology is applied in the accessory well of a coal mine in Niaoshan, Heilongjiang, China. The stability of the surrounding rock support structure is calculated and analyzed by comparing the ideal elastic-plastic model and equivalent jointed rock mass strain-softening model. The results show that a support structure designed based on the ideal elastic-plastic model cannot meet the stability requirements of the surrounding rock and that radial deformation of the surrounding rock reaches 300 mm. The support structure designed based on the equivalent joint strain-softening model has a convergence rate of surrounding rock deformation of less than 1 mm/d after 35 days of application. The surrounding rock deformation is finally controlled at 140 mm, indicating successful application of the support technology.

Deep Rock Mass Engineering: Excavation, Monitoring, and Control

“…The sixth paper, authored by X. Liu, A. Jiang, Q. Fang, Y. Wan, J. Li, and X. Guo [6], used the virtual image method, Mindlin's solution, and subgrade reaction analysis to analyze the deformation of an existing pipeline, which was located directly above the new shield tunnel. The seventh paper, written by J. Zhang, Y. Wang, B. Yao, D. Chen, C. Sun, and B. Jia [7], analyzed the peak strain-softening properties of rock mass based on the equivalent joint strain-softening theories. In the eighth paper, C. Huang, X. Li, and M. Wen [8] proposed a modified double-K fracture criterion and created an XFEM-FCM algorithm to carry out the fracture process of concrete linings.…”