Brittleness evaluation of gas-bearing coal based on statistical damage constitution model and energy evolution mechanism  

基于统计损伤本构模型和能量演化机理的含瓦斯煤岩脆性评价方法

作　　者：XUE Yi WANG Lin-chao LIU Yong RANJITH P G CAO Zheng-zheng SHI Xu-yang GAO Feng KONG Hai-ling 薛熠;王林潮;刘勇;RANJITH P G;曹正正;时旭阳;高峰;孔海陵

机构地区：[1]Institute of Geotechnical Engineering,Xi’an University of Technology,Xi’an 710048,China [2]State Key Laboratory Cultivation Base for Gas Geology and Gas Control,Henan Polytechnic University,Jiaozuo 454003,China [3]Department of Civil Engineering,Monash University,Building 60,Melbourne,Victoria 3800,Australia [4]State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221006,China

出　　处：《Journal of Central South University》2025年第2期566-581,共16页中南大学学报(英文版)

基　　金：Project(52274096)supported by the National Natural Science Foundation of China;Project(WS2023A03)supported by the State Key Laboratory Cultivation Base for Gas Geology and Gas Control,China。

摘　　要：Accurate assessment of coal brittleness is crucial in the design of coal seam drilling and underground coal mining operations.This study proposes a method for evaluating the brittleness of gas-bearing coal based on a statistical damage constitutive model and energy evolution mechanisms.Initially,integrating the principle of effective stress and the Hoek-Brown criterion,a statistical damage constitutive model for gas-bearing coal is established and validated through triaxial compression tests under different gas pressures to verify its accuracy and applicability.Subsequently,employing energy evolution mechanism,two energy characteristic parameters(elastic energy proportion and dissipated energy proportion)are analyzed.Based on the damage stress thresholds,the damage evolution characteristics of gas bearing coal were explored.Finally,by integrating energy characteristic parameters with damage parameters,a novel brittleness index is proposed.The results demonstrate that the theoretical curves derived from the statistical damage constitutive model closely align with the test curves,accurately reflecting the stress−strain characteristics of gas-bearing coal and revealing the stress drop and softening characteristics of coal in the post-peak stage.The shape parameter and scale parameter represent the brittleness and macroscopic strength of the coal,respectively.As gas pressure increases from 1 to 5 MPa,the shape parameter and the scale parameter decrease by 22.18%and 60.45%,respectively,indicating a reduction in both brittleness and strength of the coal.Parameters such as maximum damage rate and peak elastic energy storage limit positively correlate with coal brittleness.The brittleness index effectively captures the brittleness characteristics and reveals a decrease in brittleness and an increase in sensitivity to plastic deformation under higher gas pressure conditions.脆性是评估岩石力学性能的重要指标,准确评估脆性对钻井和水力压裂设计具有重要指导意义。为探究不同瓦斯压力下煤岩的脆性演化特征,本研究提出了一种基于统计损伤本构模型和能量演化机理的含瓦斯煤岩脆性评价方法。首先,结合有效应力原理与Hoek-Brown准则,建立了含瓦斯煤岩的统计损伤本构模型,并通过不同瓦斯压力下的三轴压缩试验进行了验证。随后,基于能量演化机理,分析了两个能量特征参数:弹性能量比例P_e和耗散能量比例P_d,并结合损伤应力阈值σ_(ea)和σ_(eb),探讨了含瓦斯煤岩的损伤演化特征。最后,将能量特征参数与损伤参数相结合,提出了一种新的脆性指数BIE。结果表明,统计损伤本构模型得到的理论曲线与试验曲线具有较高的吻合度,准确反映了含瓦斯煤岩的应力-应变特性,并揭示了煤在峰值后阶段的应力下降特征和软化特征。形状参数n和尺度参数F_0分别表征煤岩的脆性和宏观强度。随着瓦斯压力从1 MPa增加到5 MPa,n和F_0分别降低了22.18%和60.45%,表明煤岩的脆性和强度降低。最大损伤速率D′_(max)与峰值弹性能储存极限U_e~(max)与煤岩的脆性呈正相关。新建立的脆性指数BIE有效地反映了含瓦斯煤岩的脆性特征,揭示了在较高瓦斯压力下煤岩脆性降低及对塑性变形敏感性增加的现象。

关 键 词：gas pressure statistical damage constitutive model energy evolution mechanism brittleness evaluation gas bearing coal 

分 类 号：TD713[矿业工程—矿井通风与安全]