预测与控制矿体开采覆岩裂隙带发育高度，是沉积型层系矿体上行开采与保水开采的关键。基于空隙量守恒理论，分析了上覆岩层随采动空隙扩散的岩移规律，以矿体采高、覆岩碎胀系数、裂隙带残余空隙率、顶板垮落和放顶高度为主控因素，建立了预测覆岩裂隙带发育高度的裂隙拱模型H_{\mathrm{1}}=f\left(H,k,{\epsilon }_{\mathrm{1}},h\right)。结合山西某煤下铝土矿采区上行开采的技术条件与采矿方案，开展了相似模拟试验，分析了覆岩空隙扩散规律。同时，在煤下铝土矿开采裂隙带高度模型的基础上，分析了采高、放顶高度与裂隙带高度之间的关系，提出了确定煤下铝土矿采高与放顶高度的方法。通过数值模拟和“三带”理论验证了基于空隙率守恒的裂隙带高度预测模型的有效性和煤下铝土矿开采技术方案的可行性。本文提出的覆岩裂隙带高度模型为预测裂隙带高度与制定覆岩移动控制方案提供了新方法和有益借鉴。

Prediction and control of the development height of overburden fracture zone in ore-mining is the key of upward mining and water-retaining mining for sedimentary stratum series.When mining in layered strata，the process of caving zone and fractured zone of overlying strata movement tending to bending subsidence zone can be regarded as the result of the diffusion of voids in goaf from bottom to top.When the seam mining span is small，fractures in the overburden arched upward，and formed “fracture arch”. As the voids in the fracture arch continue to spread upwards，when the rock voidage in the fractured arch reaches the residual dilatancy coefficient under the action of rock pressure compound extrusion，the stress equilibrium state is formed between the mining affected area and the outer rock strata. At this time，the fracture arch no longer rise upward. Increasing the mining span of the seam will break the form of fracture arch and make the range of fracture arch to fracture zone. The highest arch height of the fracture arch the same as the height of the fracture zone. Above the height range of the fracture arch is the bending subsidence zone.Based on the theory of void conservation in this paper，the strata movement rule of overlying strata with mining void diffusion was analyzed. By analyzing the limiting geometry condition of fractured arch developing upward with mining-induced voids，while taking mining height，expansion coefficient of overburden rock，residual voidage，height of roof caving as main control factors，the fissure arch model for predicting development height of overburden fracture zone was established H_{\mathrm{1}}=f\left(H,k,{\epsilon }_{\mathrm{1}},h\right). Combined with the technical condition and upward mining method of a bauxite ore under coal seams in Shanxi，the similar simulation test was carried out to study and analyze the diffusion rule of overlying rock voids.When the movement range of overburden grows to the integral sinking horizon with excavation steps，increasing the stope width leads to the development of fracture zone from arch to inverted trapezoid or saddle shape.The movement zone in the overburden gradually develops upward to the integral sinking horizon，which is characterized by bending subsidence zone.The bauxite dilatancy coefficient of alu-minum strata under coal is about 10%.Based on the height model of fracture zone in under-coal bauxite mining，the relationship among mining height，caving height and fracture zone height was analyzed.When the distance between coal and bauxite is 32.0 m and the mining height of bauxite is 3.0 m，the caving height is 4.0 m. A method for determining the mining height and caving height of under-coal bauxite ore was proposed. Through numerical simulation and “three zone theory” analysis，the effectiveness of fracture zone height prediction model based on void conservation and the feasibility of mining method for under-coal bauxite ore were proved. The prediction model proposed in this paper provides a new method and a useful reference for predicting the height of overburden fracture zone and making the control scheme of overlying rock movement.