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为得到水平应力对顶板垮落角的影响,进而确定高位抽采钻孔布孔参数,采用理论分析及相似材料模拟实验的方法进行了研究。首先依据基本顶断裂位置围岩结构力学模型,将顶板岩层假设为梁结构,得到单一岩梁在不同水平应力作用下的断裂线位置变化规律。然后将各岩梁的断裂线位置叠加组合,得到水平应力对垮落角发育的影响。为验证理论分析结果,以水平应力值为影响因素设计了三组不同水平应力值条件下的双向加载相似材料模拟实验,得到了不同水平应力值对应的垮落角。研究结果表明:顶板垮落角由各岩梁断裂线位置决定。地基系数较小时,断裂线与地基初始接触位置距离随水平应力的增加表现为先减小后增加,垮落角变化规律同样为先减小后增加,但减小不明显;当地基系数增加时,随水平应力增加,断裂线与地基初始接触位置的距离减小趋势逐渐消除,仅表现为增加趋势,垮落角变化同样表现为增加趋势。现场应用表明,采用双向加载模型得到的垮落角对钻孔布置参数进行优化,优化后钻场抽采浓度及高浓度抽采时间均得到提高。
In order to obtain the effect of horizontal stress on roof caving angle and to determine the parameters of high-level drilling holes, theoretical analysis and simulation experiment of similar materials were carried out. First, according to the mechanics model of the surrounding rock mass at the location of the basic roof fracture, the top rock strata is assumed to be the beam structure, and the variation rule of the fracture line under different horizontal stresses is obtained. Then, the fracture line position of each rock beam is superposed and combined to obtain the effect of horizontal stress on the development of collapse angle. In order to verify the theoretical analysis results, the simulation experiment of three-dimensional similar materials under different horizontal stress levels was designed with the horizontal stress as the influencing factor, and the corresponding collapse angles of different horizontal stress values were obtained. The results show that the roof caving angle is determined by the fracture line of each rock beam. When the coefficient of foundation is small, the distance between the initial contact position of fault line and ground foundation decreases first and then increases with the increase of horizontal stress, and the variation law of collapse angle decreases first and then increases, but the decrease is not obvious. When the coefficient of local foundation increases . With the increase of horizontal stress, the distance between the fault line and the initial contact position of the foundation decreases gradually and gradually decreases, showing only an increasing trend. The variation of the falling angle also shows an increasing trend. The field application shows that the layout parameters of the borehole are optimized by using the collapse angle obtained by the bidirectional loading model. After optimization, both the drilling site concentration and the high-concentration extraction time are improved.