Stochastic assessment of hard rock pillar stability based on the geological strength index system,Geomechanics and Geophysics for Geo-Energy and Geo-Resources

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Stochastic assessment of hard rock pillar stability based on the geological strength index system
Geomechanics and Geophysics for Geo-Energy and Geo-Resources ( IF 5 ) Pub Date : 2021-05-04 , DOI: 10.1007/s40948-021-00243-8
Chuanqi Li , Jian Zhou , Danial Jahed Armaghani , Wenzhuo Cao , Saffet Yagiz

Abstract

Hard rock pillar is a crucial rock mass structure to maintain the stability of underground mine. It needs of special attention to analyze its stability from the point of rock mass quality. In this paper, the geological strength index (GSI) representing the rock mass quality of the hard rock pillar is examined as a new influence factor of stability, and combined with the conventional parameters (uniaxial compressive strength (UCS) of intact rock mass, width of pillar (w), height of pillar (h), the ratio of pillar width to its height (w/h)) to complete the stochastic assessment of the stability of hard rock pillar. The 47 actual cases of hard rock pillar improved by numerical simulation software Flac^3D. An empirical formula fitted by the Least Square method and artificial intelligence prediction models are used to estimate the pillar strength combining with the pillar stress to conduct the probability and reliability analysis in the Monte Carlo simulation. The result of stochastic assessment showed that UCS and w still play a vital role in maintaining pillar stability, but the influence of GSI cannot be ignored. It found that the GSI has a greater influence on the sloughing pillars in comparison with stable and failed hard rock pillars. Concluding remarks is that GSI has crucial effects on the stability of hard rock pillars as well as UCS of the rock mass and shape of pillars (w and h). Thus, the GSI should be considered as one of input parameter for pillar design and stability assessment in underground mines.

Article highlights

A new empirical formula and artificial intelligence models considering five parameters(GSI, UCS, w, h and H) are developed with the improved 47 actual cases of hard rock pillar to estimate the pillar strength.
Two pillar performance functions are determined by the Monte Carlo Simulation technique to complete the stochastic assessment based on the probability and reliability analysis of stability conditions of hard rock pillars.
The probability of different conditions of pillars can well indicate the relationship between the new (GSI) and traditional influencing factors (UCS, w, h and H) and the stability of pillars.
The GSI index has a greater influence on the sloughing pillars in comparison with stable and failed hard rock pillars.

中文翻译：

基于地质强度指标体系的硬岩柱稳定性随机评估

摘要

硬岩柱是维持地下矿井稳定性的关键岩体结构。从岩体质量的角度分析其稳定性需要特别注意。本文将代表硬岩柱体质量的地质强度指标（GSI）作为稳定性的新影响因素进行了研究，并与常规参数（完整岩体的单轴抗压强度（UCS），宽度（w）的高度，高度（h）的高度，宽度与高度的比（w / h）），以完成对硬岩柱稳定性的随机评估。数值模拟软件Flac改进了47个硬岩柱的实际案例^3D。利用最小二乘方法和人工智能预测模型拟合的经验公式，结合柱应力估计柱强度，进行蒙特卡洛模拟的概率和可靠性分析。随机评估的结果表明，UCS和w在保持支柱稳定性方面仍起着至关重要的作用，但是GSI的影响不容忽视。研究发现，与稳定和失效的硬岩柱相比，GSI对下陷柱的影响更大。结论是，GSI对硬岩柱和UCS的稳定性具有至关重要的影响的岩石质量和柱子形状（w和h）。因此，应将GSI视为地下矿柱设计和稳定性评估的输入参数之一。