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高预紧力均布承载型锚杆力学响应及应用

Key technology and application of pre-stressed anchor to improve pre-tightening force

  • 摘要: 预紧力作为锚杆支护的关键参数之一,对主动支护起着决定性作用,国内外研究表明提高锚杆预紧力可降低冒顶事故的发生,为有效提高锚杆预紧力、降低断锚、失锚的现象发生。研发了滚动式减摩垫片和拉压分离型螺母,综合采用实验室试验、理论分析、数值计算,研究了滚动式减摩垫片、拉压分离型螺母转矩-预紧力转化关系,研究了普通螺母、拉压分离型螺母预紧过程中力学响应特征。研究表明:普通锚杆预紧过程中,约有60%转矩被锚杆螺母与托盘之间的摩擦所消耗,使用滚动式减摩垫片可将摩擦消耗的转矩降低至25%,转矩-预紧力转化率提高2倍左右;普通锚杆螺母内螺纹副应力沿着远离挤压面轴向呈指数衰减,螺母内前3圈应力值较大,该范围发生明显的应力集中,为锚杆杆体断裂的危险面,使用拉压分离型螺母后螺纹副应力呈均匀分布,消除了应力集中现象,螺纹变形协调;集成滚动式减摩垫片、拉压分离型螺母等发明了高预紧力均布承载型锚杆,可将预紧力提升至2.5倍,杜绝锚杆易从螺纹段断裂的现象,在淮南矿区朱集矿得取得良好的应用效果。

     

    Abstract: As one of the key parameters of bolt support, pre-tightening force plays a decisive role in active support. Domestic and foreign research shows that increasing the pre-tightening force of bolt can reduce the occurrence of roof fall accidents, so as to effectively improve the pre-tightening force of bolt and reduce the occurrence of broken anchor and lost anchor. The rolling anti-friction washer and tension-compression separation nut were developed. The torque-preload conversion relationship of the rolling anti-friction washer and tension-compression separation nut was studied by laboratory experiment, theoretical analysis and numerical calculation. The mechanical response characteristics of the common nut and tension-compression separation nut during pre-tightening process were studied. The research shows that about 60% of the torque is consumed by the friction between the bolt nut and the tray during the pre-tightening process of the ordinary bolt. The torque consumed by the friction can be reduced to 25% by using the rolling anti-friction gasket, and the torque-pretightening force conversion rate is increased by about 2 times. The stress of the internal thread pair of the ordinary bolt nut decreases exponentially along the axial direction away from the extrusion surface. The stress value of the first three rings in the nut is larger, and the stress concentration occurs obviously in this range, which is the dangerous surface of the bolt body fracture. The stress of the thread pair is evenly distributed after using the tension-compression separation nut, which eliminates the stress concentration phenomenon and the thread deformation is coordinated. The high pre-tightening force uniform bearing bolt was invented by integrating rolling friction reducing gasket, tension-compression separation nut, etc., which can increase the pre-tightening force to 2.5 times, eliminate the phenomenon that the bolt is easy to break from the thread section, and achieve good application effect in Zhuji Mine of Huainan Mining Area.

     

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