水压轴压联合作用下煤岩的统计损伤本构模型研究

Research on statistical damage constitutive model for coal-rock subjected to hydraulic pressure and pulldown

从煤岩内部节理、裂隙和物质分界面等缺陷的随机性分布特征出发,基于反映煤岩内部缺陷的微元强度服从Weibull分布的概念,建立了水压和轴压联合作用下煤岩的损伤本构模型.以东庞北井9#煤静态压缩试验为基础确定了模型里面的相关参数,并得出了与峰值应力对应的累积损伤度(即临界损伤度).研究结果表明:(1)模型参数少且易于确定;(2)模型能反映围压效应,即可以体现煤岩体强度随水压变化的规律;(3)模型参数确定方法揭示了模型参数的物理意义;(4)可以通过不同围压下煤岩体应力-应变全曲线特征及在不同围压下峰值应力与应变之间的关系来确定模型参数;(5)在弹性矩阵中引入孔隙水压力影响因子来考虑孔隙水压力对煤岩损伤本构模型的影响,这种方法被证明是可行的.

The statistical damage constitutive model for coal-rock subjected to hydraulic pressure and pulldown was established based on the random distribution property of the inner flaw, such as joint, cranny and interface, and the conception that the infinitesimal element strength of the inner flaw in the coal-rock satisfies the Weibull distribution. The correlative parameters were determined by axial compression experimention of 9# coal in the north mine shaft of the DONG PANG colliery, and the damage cumulation （ critical damage ） corresponding to peak stress were obtained. The results show： （1）There are only three parameters in this model and they can be determined. （2）The model can reflect the confining pressure effect, namely the regularity of the coal rock strength changing with the hydraulic pressure could be showed. （3） The way of determining the parameters indicated the physical meaning of the parameters of model. （4）The statistical pa- rameters in the constitutive model can be obtained by the characteristics of the full stress-strain curve of coal rock and the relationship between the characteristic parameters （ the stress and strain at the peak-stress point ） under dissimilar hy- draulic pressure. （5）The effect of the pore water pressure to the statistical damage constitutive model for coal-rock was considered by introducing the influencing factor of pore water pressure in the elasticity matrix. This method proved feasible.