真三轴状态下煤岩单体的强度变形特性及破坏模式研究

Study on Strength,Deformation and Failure Mode of Coal-Rock Single Body under True Triaxial Comprssion Condition

煤矿巷道顶板具有特殊的煤—岩层状结构,研究煤岩单体的强度变形特征,对于巷道稳定性控制有着重要意义。以山西华晋韩咀煤矿为工程背景,使用中国矿业大学自行研制的岩石真三轴电液伺服加载试验系统分别对煤和岩石相似材料开展真三轴试验,分析了真三轴条件下中间主应力对两者在强度及变形方面的影响。研究表明:二者的峰值强度与峰值应变都随着中间主应力的增大而呈现出先增加后减小的趋势,且这种趋势受到最小主应力的影响;在中间主应力不断增大的过程中,煤样的破坏经历了从剪切破坏向劈裂—剪切组合破坏的过程;此外,当中间主应力过大时,二者会经历延性—脆性转化的过程。上述分析表明:中间主应力对煤岩体的破坏起到先保护后促进的作用。

The roof of coal mine roadway has a special layered structure of coal-rock,so it is of great significance to study the strength and deformation characteristics of coal-rock single body for the control of roadway stability.In this paper,taking Hanzui Coal Mine in Shanxi Province as the engineering background,the true triaxial tests of coal samples and rock-like material were carried out respectively by the self-developed true three-axis electro-hydraulic servo control system of China University of Minging and Technology.The influence of intermediate principal stress on their strength and deformation under true triaxial condition was analyzed.The study resluts show that their peak strength and peak strain first increases and then decreases with the increase of intermediate principal stress,which is affected by the minimum principal stress.In the process of increasing intermediate principal stress,the failure of coal samples experienced from shear failure to splitting-combined shear failure.In addition,when the intermediate principal stress is too large,they will experience the transformation process from ductility to brittleness.The above phenomenon shows that the intermediate principal stress plays a role of first restraining and then promoting the failure of coal and rock.