Ground stability of underground gateroad with 1 km burial depth: A case study from Xingdong coal mine, China

Abstract

This paper presents an integrated investigation of the ground stability of a deep gateroad with a 1 km burial depth based on a field test, case studies, and numerical modelling. In situ stress measurements and mechanical properties tests were first conducted in the test site. Then, the deformation behavior, stress and yield zone distributions, as well as the bolts load of the gateroad, were simulated using FLAC^3D software. The model results demonstrated that the soft rock properties and high in situ stress were the main factors for the deep gateroad instability, and the shear slip failure induced by the high stress was the primary failure model for the deep rock mass. In addition, the unsuitable support patterns, especially the relatively short bolts/cables with low pre-tensions, the lack of high-strengthen secondary supports and the unsupported floor strata, also contributed to the gateroad instability. Subsequently, a new combined supporting strategy, incorporating longer bolts/cables, yielding ring supports, and grouting measures, was proposed for the deep gateroad, and its validity was verified via field monitoring. All these could be a reference for understanding the failure mechanism of the gateroad with 1 km burial depth.

摘要

本文采用数值模拟、案例分析、现场试验相结合的综合研究方法分析千米埋深煤矿巷道围岩稳 定性。首先,在试验巷道进行了地应力监测与煤岩体力学性能测试;然后,通过FLAC^3D 数值模拟软 件分析了试验巷道围岩位移场、应力场、塑性区与锚杆受力特征。研究结果表明,软岩特性与高地应 力是深部巷道失稳的主要因素,高应力引起的剪切滑移破坏是深部巷道围岩的主要破坏模式;不合理 的支护方式,特别是锚杆索长度短且预紧力低、缺少高强二次支护、底板无支护等亦是巷道失稳的原 因。基于上述研究,提出了集长锚杆索、可缩性环形支架、注浆加固于一体的联合加固措施,并通过 现场监测验证了支护方案的合理性。本文研究成果为深入理解千米深井巷道破坏机制提供了借鉴。