条带煤柱设计的强度准则效应研究

条带开采广泛应用于深部煤层,合理的条带煤柱尺寸对提高煤炭采出率和保护地表地貌都具有十分重要的意义。通过总结平面应变状态下Wilson准则、Mohr-Coulomb(M-C)准则、广义Matsuoka-Nakai(M-N)准则、广义Lade-Duncan(L-D)准则和外接圆Drucker-Prager(D-P)准则等5种强度准则的统一表达式,进而建立条带煤柱的极限强度、屈服宽度和留设宽度的统一计算公式,探究条带煤柱设计的强度准则效应,并得出煤层黏聚力和内摩擦角的影响特性。研究结果表明:建立的统一计算式涵盖文献已有解,且应用非常方便;条带煤柱设计的强度准则效应显著,Wilson准则和M-C准则的结果过于保守,外接圆D-P准则应用需谨慎,应优先选用广义M-N准则或广义L-D准则;煤层黏聚力和内摩擦角对条带煤柱设计的影响明显,应充分考虑煤层的强度参数变化。该研究结果可为条带煤柱的合理设计与施工提供一定的理论指导。

Effect of strength criterion on design of strip coal pillar

The strip coal pillar method is widely used in deep coal seams mining. The reasonable strip coal pillar size is of great significance to improve the coal recovery rate and protection of surface topography. Under the plane strain state, a unified formula is firstly summarized for five strength criteria, such as Wilson criterion, Mohr-Coulomb (M-C) criterion, generalized Matsuoka-Nakai (M-N) criterion, generalized Lade-Duncan (L-D) criterion and circumcircle Drucker-Prager (D-P) criterion. Then, the unified formula of limit strength, yielding width and remained width for strip coal pillar is presented. Finally, the effect of strength criterion is investigated and parametric studies are discussed. The results show that the obtained unified formula covers existing solutions in the literature and its application is very convenient; the effect of strength criterion on the strip coal pillar design is significant; the results of Wilson and M-C criteria are in too conservation, while the use of circumcircle D-P criterion is need to be cautious; moreover, the generalized M-N criterion or generalized L-D criterion is recommended to be adopted; the influence of changes in strength parameters (cohesion and inner friction angle) of coal seam on the strip coal pillar design is remarkable and should be fully considered. The obtained results can provide some theoretical guidance in reasonable design and construction of strip coal pillars.