建立基于突变理论的采空区重叠顶板稳定性强度折减法,研究重叠顶板的安全储备。提出采空区重叠顶板安全系数的概念,通过不断折减重叠顶板强度参数,得到不同折减系数下重叠顶板中点的竖向位移序列,建立其竖向位移序列与折减系数的尖点突变模型,以此作为采空区重叠顶板是否失稳的判据。以双层长方体采空区重叠顶板为例,得到不同顶板跨度下,重叠顶板安全系数和厚跨比之间的对数拟合函数,表明重叠顶板安全系数受顶板厚跨比和跨度双重影响。采用基于突变理论的采空区重叠顶板稳定性强度折减法对多层采空区重叠顶板进行稳定性分析,得出上层采空区重叠顶板不稳定会促使下层采空区重叠顶板向不稳定演化。对高峰矿区105#矿体多层复杂采空区重叠顶板稳定性进行分析后可知:除1#,2#采空区重叠顶板外,其余重叠顶板基本稳定,其安全系数在1.50以上。基于突变理论的采空区重叠顶板稳定性强度折减法为研究采空区稳定性提供一种新的研究途径。
Strength reduction method which is used to study stability of goaf overlapping roof based on catastrophe theory is established.The concepts of safety factor of overlapping roof are proposed.With the reduction of strength parameters,a cusp catastrophe model of vertical displacement of the midpoint of roof and reduction coefficient is built.The mutability of overlapping roof failure process can be reflected when this model is employed as the failure criterion.Taking double cuboid goafs for example,fitting logarithm function between safety factor of roof and thickness to span ratio is drawn.Fitting function shows that safety factor of roof is effected by the thickness to span ratio and span of roof.Using strength reduction method to study stability of multilayer goafs overlapping roof based on catastrophe theory,it is obtained that the upper goaf overlapping roof instability can induce instability evolution of the lower goaf overlapping roof.Studying the stability of multilayer goafs overlapping roofs in No.105 tin orebody of Gaofeng mining area,as result,except for goafs No.1 and No.2,the rest overlapping roofs are stable in the main,whose safety factors are over 1.5.Strength reduction method based on catastrophe theory provides a new research approach for stability analysis of goafs.