高位硬厚岩层弹性基础边界下破断规律的演化特征

Evolutionary characteristics of fracture laws of high-position hard thick strata with elastic foundation boundary

以某矿首采工作面上覆高位岩浆岩条件为背景,根据高位硬厚岩层的空间结构及边界基础特征,建立了高位硬厚岩层弹性基础支承下的Winkler基础正交梁力学模型,推导出高位硬厚岩层走向和倾向的弯矩及挠度表达式,得到了特征弯矩及其位置的计算式,分析了特征弯矩在工作面推进过程中的演化规律.研究表明:高位硬厚岩层在边界基础支承下,走向及倾向的最大弯矩和起始破断位置在采空区中部,具有边界基础变形效应.初次破断步距随工作面长度的增加呈现似"W"型变化趋势,并分为稳定、步距变化和步距稳定3个阶段;随弹性基础特征参数β的增大呈现单调递增的变化趋势.采用弹性基础正交梁理论可预测高位硬厚岩层的破断步距,并通过工程实例验证了考虑边界弹性基础变形效应是合理的.

Taking conditions of overlying magmatic of the first working face in a certain mine as background, a Winkler foundation orthogonal beam model under support of elastic foundation was built according to space structure and boundary foundation characteristics of high-position hard thick strata. Moment and deflection expressions of the strata along strike and tendency were derived respectively, the formulas of characteristic bending moment and its location were obtained, and the evaluation laws of characteristic bending moment with the advanced of work- ing face were also analyzed. The results show that maximum moment and initial failure location along strike and tendency occur at middle of goal under the boundary foundation support of high-position hard thick strata, which indicates the boundary foundation deform effect. With the increase of face length, the first failure span presents a W-shaped variation trend, which can be divided into three stages, namely stage of stable, span changing and spans stabilizing. The first failure span also presents a monotonically increasing trend with the increase of the e- lastic foundation characteristic coefficient 8. By adopting the elastic foundation orthogonal beam theory, the failure span of high-position hard thick strata is predictable, and the rational- ity of taking boundary elastic foundation effect into account is verified with case study.