采空区顶板冒落数值模拟模型边界尺寸确定及冒落规律

结合赵庄煤矿综采工作面顶底板岩层性质,在通用离散元软件UDEC中建立物理模型,对比了不同上边界、侧向边界尺寸模型数值模拟结果中老顶的下沉量,确定了为消除边界效应所需的模型边界.结果显示,模型上边界尺寸大于70 m,侧向边界尺寸大于100 m时,才能得到可靠的模拟结果.得到了不同工作面推进距离条件下的老顶冒落下沉规律,当推进距离大于300 m后,老顶沿推进方向在采空区中部最大下沉量不变;从采空区边界处开始随向采空区内部深入中粒砂岩下沉量逐渐增加,在距离采空区边界100 m左右增加至最大值2.70 m;随着距工作面距离增加,老顶中粒砂岩下沉量呈线性增加,在工作面后方120 m位置处下沉量达最大值2.70 m.

Determination of model boundary sizes in numerical simulation of roof falling in gob and study of roof falling law

Combined with the roof and floor rock properties of the fully mechanized coal mining face in Zha- oZhuang coal mine, this paper establishes a physical model in universal distinct element code UDEC, com- pares the subsidence of the main roof in numerical simulation models of different upper boundaries and lateral boundaries, and determines the rational boundary sizes of the model which could eliminate the boundary effects. The law for the main roof falling and subsiding is determined when the coal mining face reaches differ- ent advance distances. When the advance distance is greater than 300 m, the maximal subsidence of the main roof would be invariable in the middle of the gob along the advance direction ; the subsidence of medium sand- stone increases gradually as the location goes deep into the gob from the gob boundary, the subsidence reaches the maximum value 2.7 m in the location where the distance is 100 m apart from the gob boundary; as the dis- tance from coal mining face increases, the subsidence of main roof increases linearly, reaching the maximum value in the location where the distance is 120 m behind the coal mining face.