冲击倾向性煤体强度尺寸效应的影响因素研究

Study on influencing factors of strength size effect based on bump-prone coal

为理清煤体强度尺寸效应数值模拟过程中力学参数折减的原因,以强度尺寸效应作为问题切入点,通过实验室试验探讨强冲击倾向性煤体强度尺寸效应,结合最弱链理论的Weibull分布推导强度尺寸效应的理论公式,利用数值模拟研究强度尺寸效应的影响因素。研究结果表明:冲击倾向性煤体强度具有明显的尺寸效应,随着尺寸(长、宽、高)增大,强度降低,两者符合指数函数关系;概率统计分布能够表达出强度尺寸效应内在本质,指出均质度m是煤岩体强度尺寸效应的主要影响因素;数值模拟结果显示:在尺寸一定时,随着均质度增大,煤岩强度表现为上凸的增长曲线,按照强度大小变化可划分为3个阶段,即波动上升阶段、快速增长阶段、渐缓增长阶段;随着均质度增大,强度趋于收敛,极限值即为煤岩体细观尺寸强度;随着均质度增大,尺寸变化对强度的影响程度降低。

In order to clarify the reasons of mechanics parameters reduction in the numerical simulation process,the strength size effect was taken as the starting point of the problem.The external appearance of strength size effect about strong bump-prone coal was studied by laboratory test.The theoretical formula of strength size effect was deduced based on the Weibull distribution of the weakest chain theory,and the inherent nature of strength size effect was revealed.The influencing factors of strength size effect were discussed by means of numerical simulation.The results show that:the bump-prone coal has obvious size effect.As the size(length,width and height)increases,the strength decreases,which was well in accordance with the exponential function relationship;The probability and statistical distribution can express the intrinsic nature of the intensity size effect,indicating the homogeneity m is the main influencing factor of the strength effect of coal-rock mass.Numerical simulation results show that when the size is constant,the strength of coal rock shows an upward convex curve with the increase of homogeneity,which can be divided into three stages:namely the rising phase of volatility,the stage of rapid growth,and the stage of gradual growth.With the increase of homogeneity,the strength tends to converge,and the limit value is the meso size strength of coal and rock mass;when the homogeneity increases,the effect of size change on the strength decreases.