摘要
为探究废弃矿井地下水库人工坝-煤组合体强度劣化失稳机制,建立考虑倾角与含水共同作用的组合体强度劣化失稳模型,开展5种倾角和3种含水率下的组合体单轴压缩试验,分析倾角与含水共同作用下人工坝-煤组合体强度、裂纹演化及失稳破坏特征,探讨倾角、含水率及其共同作用下人工坝-煤组合体强度失稳机制及其主控因素。构建考虑人工坝-煤组合体“三区”强度、界面粗糙度与界面黏结特性的强度模型,并验证模型可靠性。与干燥试样不同,饱和试样平均单轴抗压强度在0°~60°时逐渐减小,在60°~90°时逐渐增大,在60°达到极小值,水的存在降低了单轴抗压强度转折点。在倾角与含水率共同作用下,人工坝-煤组合体在界面倾角30°~45°之间存在“饱和诱失点”,而在45°~60°之间存在“干燥诱失点”,这是“三区”强度共同作用的结果。随着界面倾角增大,人工坝-煤组合体逐渐由以拉-剪复合破坏为主转变为界面滑移破坏。分析CR-90试样时,除考虑“三区”强度外,人工坝与煤体的变形差异诱发的界面不均匀变形也是决定其破坏模式的关键因素。含水会削弱人工坝-煤组合体“三区”强度,不仅会侵蚀、润滑和软化人工坝区与煤区的力学特性,还会影响界面连通区稳定性,降低界面粗糙度,继而削弱界面黏结特性,使人工坝-煤组合体整体稳定性降低。基于Drucker-Prager强度准则,建立人工坝-煤界面区强度表达式,定性分析界面区破坏失稳的多因素性,综合认为界面应力状态是导致人工坝-煤组合体强度失稳的主要因素。不同倾角下,含水人工坝-煤组合体在界面倾角为0°~45°,45°~60°和60°~90°时,影响组合体强度失稳的主控因素分别为界面倾角、含水率和界面倾角。研究成果可为废弃矿井地下水库人工坝-煤组合体的稳定性控制提供理论依据。
In the hope of exploring the strength degradation and instability mechanism of the artificial dam-coal composite(hereafter referred to as the composite)in underground reservoirs of abandoned mines,a strength degradation and instability model of the composite considering both dip angle and water content was established.Subsequently,uniaxial compression tests were performed on the composite under 5 dip angles and 3 water contents.Based on the test results,the strength,crack evolution,and instability failure characteristics of the composite under the joint action of dip angle and water content were analyzed,and the strength degradation and instability mechanism and dominant factors of the composite under the dip angle,water content,as well as their joint action were discussed.Moreover,a strength model considering the strength of"three zones",interface roughness,and interface bonding characteristics of the composite was established,and its reliability was verified.Different from that of dry samples,the average uniaxial compressive strength of saturated samples gradually decreases within the interface dip angle range of 0°-60°and increases within the interface dip angle range of 60°-90°,reaching the minimum value at 60°.The presence of water lowers the turning point of uniaxial compressive strength.Under the joint action of dip angle and water content,a"saturation-induced loss point"and a"drying-induced loss point"exist within the interface dip angle ranges of 30°-45°and 45°-60°,respectively,which is attributed to the joint action of the strength of"three zones".As the interface dip angle increases,the dominant failure mode of the composite gradually changes from tensile-shear composite failure to sliding failure at the interface.In the analysis on the CR-90 samples,in addition to the strength of"three zones",the uneven deformation of the interface induced by deformation difference between artificial dam and coal body is also an important factor that determines its failure mode.Water weakens the strength of"three zones".It not only erodes,lubricates,and softens the artificial dam area and the coal area,but also affects the stability of the connecting area at the interface,reduces the roughness of the interface,and further weakens the bonding at the interface,eventually impairing the overall stability of the composite.Based on the Drucker-Prager strength criterion,an expression for the strength of the interface zone was established,and multiple factors affecting the failure and instability in the interface zone were qualitatively analyzed.It is found that the stress state at the interface is the main cause of the strength instability of the composite.The dominant factors controlling the strength instability of the composite under different interface dip angles(0°-45°,45°-60°,and 60°-90°)are interface dip angle,water content,and interface dip angle,respectively.The research results are expected to provide a refe-rence for the stability control of the artificial dam-coal composite of underground reservoirs in abandoned mines.
作者
杨科
张寨男
华心祝
吕鑫
YANG Ke;ZHANG Zhainan;HUA Xinzhu;LYU Xin(National Key Laboratory of Deep Coal Safety Mining and Environmental Protection,Anhui University of Science&Technology,Huainan,Anhui 232001,China;Institute of Energy,Hefei Comprehensive National Science Center,Hefei,Anhui 230031,China)
出处
《采矿与安全工程学报》
北大核心
2025年第3期625-635,共11页
Journal of Mining & Safety Engineering
基金
国家自然科学基金区域创新发展联合基金项目(U21A20110)
山西省科技重大专项揭榜项目(20191101016)。
关键词
废弃矿井
地下水库
人工坝-煤组合体
界面倾角
含水率
强度模型
失稳机制
abandoned mines
underground reservoir
artificial dam-coal composite
interface dip angle
water content
strength model
instability mechanism
