Characteristics and Time-Space Evolution of Mining Stress in High Stope

Yongyue Hu,Jingjie Zhang,Yonggang Xiao,Changhong Li,Yu Wang,Zhengyang Song,Xianjie Hao

doi:10.1155/2021/2785933

Abstract

Due to the lack of relevant investigation research on the evolution of mining stress in high stope of metal mines, the understanding of how to ensure the safety during mining process is not clear at all. In this paper, by monitoring the mining-induced pressure of the surrounding rock in the 16-2# stope of Lilou Iron Mine, the evolution of the mining-induced pressure of the subsequent filling and mining method of the high-stage empty field is obtained. The study shows that there are three stages of pressure change in the second-step stope of Lilou Iron Mine: I (stress rising stage), II (stable stage), and III (pressure relief stage), and the mining stress in the surrounding rock is transferred from the top to bottom. The stress transfer model of stope is proposed, and the variation of vertical stress versus the depth is fitted; the four horizontal sections are fitted, respectively. By establishing the three-dimensional numerical model and distributed excavation simulation, the time-space evolution of mining stress is obtained and compared with the in-site measuring result. The two results show high consistency, and the effectiveness of numerical simulation is verified.

Highlights

Working Principle of Mining Stress Monitoring System. e monitoring system can realize the real-time monitoring of mining stress and automatic data storage, and the stress change in the whole mining process can be fully reflected
E axial strain along the measuring hole can be obtained by measuring the axial strain gauge, and the resultant force along the circumference of the hole can be obtained by adding 0°, 120°, and 240° of the three circumferential strain gauges. e least square method was used to analyze the 3 sets of repeated data obtained by the instrument monitoring
Horizontal section, and −400 m horizontal section is reached in turn. e surrounding rock of the roadway presents “layered ladder” stress transfer, and it is “layered ladder” stress transfer from top to bottom. e formula can be used to estimate the numerical range of the vertical stress σz of the surrounding rock of the roadway when the roadway is buried in different depths and excavated to a certain position in the stope mining process, which provides a certain guidance for the safety production of the mine

Summary

Monitoring System and Layout of Measuring Points of Stope Mining Stress

E least square method was used to analyze the 3 sets of repeated data obtained by the instrument monitoring It can be seen from formula (2) that by averaging the three axial strains in the measurement results, the requirements of three parallel measurement tests can be achieved, and the average axial strain formula is obtained [10]: εz averageE· σz − v􏼐σx + σy􏼑. The stope is redistributed, which causes stress concentration in some parts and causes a series of ground pressure behavior problems Such as roof fall and rib spalling, this makes the safety of the surrounding roadway and stope mining and workers’ lives and safety are greatly affected. After the monitoring system is installed, the instrument data must be cleared after each data extraction

Analysis of Dynamic Evolution of Mining Stress

Comparative Analysis of Numerical Simulation

Findings

Conclusion