Stability Analyses and Cable Bolt Support Design for A Deep Large-Span Stope at the Hongtoushan Mine, China

Zhao Zhao,Zhang Zhang,Yang Yang,Li Li

doi:10.3390/su11216134

Abstract

This study presents stability analyses and a cable bolt support design for a typical deep large-span stope (1-1# stope) at the Hongtoushan mine in China, using an integrated empirical and numerical method. Detailed field work including quantification of joint distribution and surface quality, along with laboratory test on intact rock samples, were performed to obtain the geotechnical properties of rock masses. The rock mass of the 1-1# stope was characterized by rock mass rating (RMR), rock mass quality (Q), and geological strength index (GSI), and then the modulus, peak strength, cohesive strength, and internal friction angle of the rock mass were estimated. The stability of the stope was then evaluated by empirical (RMR, stability graph) and numerical approaches (limit equilibrium analyses with UNWEDGE and stress-strain analyses with FLAC3D), considering of the effects of rock mass quality, induced stress, and large-span. A cable bolt support system obtained from the empirical method, was then further analyzed using the FLAC3D and UNWEDGE codes. The results show that the maximum plastic zone thickness and vertical displacement at the stope roof decrease significantly and the safety factor of the unstable wedge block increases significantly after installing the cable bolt support systems recommended by the empirical method. Therefore, it is suggested that an integrated empirical and numerical method is used to obtain quantitative stability assessment and optimum cable bolt support design for deep large-span stope roofs.

Highlights

Stope roof stability is an essential prerequisite for safe working conditions in overhand cut-and-fill mining
Gao et al [22] studied the effect of a dip angle in mining direction on drum loading performance used discrete element method (DEM)
The multi-point borehole extensometer, stress detector, and microseismic monitoring system should be carried out during mining. Both the empirical and numerical methods were conducted for stability analysis and cable bolt support design of a deep large-span stope at the Hongtoushan mine in China

Summary

Introduction

Stope roof stability is an essential prerequisite for safe working conditions in overhand cut-and-fill mining. Non-anticipated rock collapses and falls from the stope roof are the primary threat to the safety of underground workers and economic extraction of ore bodies. Such accidents account for approximately 40% of all injuries and fatalities in underground base metal mines in China [1]. Swart and Handley [10] designed a stable range of stopes for shallow mining operations using an integrated method included a stability graph, elastic beam theory, and numerical modeling. Yang et al [19] analyzed the stability of a shallow large-scale stope using stage subsequent filling mining methods in the Sijiaying iron mine in China using physical and numerical modeling methods. Many other studies have explored stope stability using instrumentation measurements [26,27,28,29,30,31]

Methods

Findings

Discussion

Conclusion