渗流条件下不同覆岩结构采动破坏数值分析

Numerical Analysis of Mining Failure of Different Overburden Structures under Seepage Condition

运用有限元软件(ADINA)建立二维模型,模拟分析渗流和采动作用下4种不同覆岩结构的破坏场和孔隙水压力分布特征。结果显示:岩性结构影响覆岩端部破坏规律,当上硬下软时,裂缝带范围以最下位岩层断裂线为界向采空区外侧扩展;当上软下硬时,以最下位岩层断裂线为界向采空区内侧方向扩展。硬岩交替型结构,裂隙带的侧边界则是内外交叉发展;岩性越硬相应导水裂隙带的高度越高。在其他条件相同时,导水裂隙带的高度由大到小的顺序为:坚硬—坚硬型、软弱—坚硬型、坚硬—软弱型和硬软交替型。

Taking the working face of a coal mine as the research object,we established the two- dimensional model by using the finite element software ADINA,and simulated and analyzed the damage field and pore- water pressure distribution characteristics of four kinds of different overburden structures under the action of seepage and mining.The results show that the lithological structure affects the failure law of the end of overburden rock.When the the upper stratum is hard and type of rock is hard-soft the lower stratum is soft,the fracture zone extends to the outside of the mined out area,which takes the limit of fault line of the lowest stratum.When the the upper stratum is soft and the lower stratum is hard,the fracture zone extends to the inside of the mined out area,which takes the limit of fault line of the lowest stratum.When the type of rock is alternating hard and soft,the lateral boundary of the fracture zone presents cross- development of internal and external.The higher the lithology is,the higher the hydraulic fracture zone is.When other conditions are the same,the heights of the water flowing fractured zone are in the following descending order：hard- hard type,soft- hard type,hard- soft type,hard and soft alternating type.