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以平面应变条件下Drucker-Prager为屈服准则,并给出强度增加系数的适用范围;采用有限元极限分析法,不断增加煤层、上覆岩层强度以至上覆岩层处于极限平衡状态,上覆岩层出现连续、贯通的塑性区,说明上覆岩层存在“塑性体”拱状结构;裂隙拱结构水平应力高于垂直应力、拱脚应力高于拱顶,符合拱结构受力特征。开采跨度增加,煤壁支撑压力不断增加,采空区底板支撑应力非常有限;裂隙拱跨度增加,拱高不断增加,拱跨比逐渐降低,说明采动对裂隙拱拱高的影响是有一定范围的。
The Drucker-Prager yield criterion is given under the plane strain condition, and the applicable range of the strength increasing coefficient is given. With the limit analysis of the finite element method, the strength of the coal seam and the overburden is increased so that the overburden is in a state of limit equilibrium and the overburden appears The continuous and through plastic zone indicates that there is a “plastic body” arch structure in the overlying strata. The horizontal stress of the fractured arch structure is higher than that of the vertical stress and the stress of the arch foot is higher than that of the arch, which accords with the stress characteristics of the arch structure. The mining span increases, the supporting pressure of the coal wall is increasing, and the support stress of the floor of the goaf is very limited. The span of the crack arch increases, the arch height increases and the arch-span ratio gradually decreases, indicating that mining has a certain range of influence on the crest arch height of.