为研究采场上覆关键层破断角,基于弹性力学和岩体力学,建立采场上覆关键层破断的梁力学模型,推导得出关键层破断角的计算公式,并通过物理模拟实验进行公式合理性和可靠性的验证。结果表明:(1)理论计算关键层破断角的变化范围为57.5°~71.0°,实验模拟破断角为50°~70°,理论计算结果与实验模拟结果吻合较好,说明理论推导关键层破断角的计算公式具有较高合理性和可靠性;(2)关键层破断角公式说明,关键层破断角与关键层的内摩擦角、抗拉强度、容重、弹性模量、关键层厚度和上覆载荷层的弹性模量、容重和厚度有关。对某一采场覆岩,关键层破断角的变化主要受关键层自身厚度和载荷层厚度的影响;(3)关键层厚度与载荷层厚度比值h/h’<1.5时,关键层破断角随h/h’的增大而减小,载荷层厚度变化对破断角的影响程度大于岩层厚度变化的影响;(4)当h/h’>1.5时,载荷层厚度增大引起关键层破断角减小,关键层厚度增大引起关键层破断角减小,两者对关键层破断角的影响作用相同,关键层厚度变化对关键层破断角的影响程度大于载荷层厚度变化的影响;(5)当h/h’=4时,关键层厚度变化与载荷层厚度变化对破断角的影响程度相同。

In order to study the breaking angle of overlying key strata in stope,based on elastic mechanics and rock mechanics,the beam mechanical model of breaking of overlying key stratum is established,and the calculation formula of rock breaking angle is derived. Simula-tion experiment was carried out to verify the rationality and reliability of the formula through physical simulation. The study shows that ① Theoretical calculation shows that the breaking angle of overlying key strata varies from 57. 5° to 71． 0°,the simulated breaking angle is 50°-70°,the theoretical results are in good agreement with the experimental results which shows that the calculation formula of rock breaking angle has high reliability and rationality;② The breaking angle formula shows that the key stratum breaking angle is related to the physical and mechanical parameters of key stratum,such as,internal friction angle,tensile strength,rock mass density, elastic modulus,rock thickness,and the physical and mechanical parameters of load strata,such as,thickness,rock mass density,and elastic modulus. For the overlying strata of a working face,the change of breaking angle is mainly affected by the thickness of the key stratum itself and the thickness of its load layers;③ When the ratio of key stratum thickness to load strata thickness h / h′1. 5,the increase of the load strata thickness will cause the breaking angle to decrease, the increase of rock thickness leads to the decrease of fracture angle. The effect of the two influencing factors on the breaking angle is the same,and the influence of the change of key stratum thickness on the breaking angle is greater than the change of the thickness of the load layer;⑤ When h / h′ = 4,the change of key stratum thickness and load strata thickness have the same influence on breaking angle.