锚杆预紧扭矩转化效率主控因素分析

Analysis on main control factors for conversion efficiency of pre-tightening torque of rock bolts

为研究锚杆预紧扭矩与预紧力转化规律,通过理论分析和现场试验,系统研究了转化效率主控因素,并基于数值模拟结果对锚杆预紧扭矩进行参数优选。研究结果表明:同一预紧扭矩下,随螺母与螺纹间摩擦因子、螺母与垫圈间摩擦因子增大,锚杆预紧力均随之减小,且减小速率呈降低趋势。对于细牙全螺纹锚杆和左旋无纵筋锚杆,当预紧扭矩超过400 N·m时,预紧力增幅随预紧扭矩增加而变缓,继续施加预紧扭矩获得的预紧力增量较小。锚杆直径越大,预紧扭矩转化效率越低,锚杆螺距越小,预紧扭矩转化效率越高。当预紧力达到80 kN时,直径18 mm细牙全螺纹锚杆和直径20 mm左旋无纵筋锚杆对应的预紧扭矩分别为408 N·m和429 N·m。研究成果对锚杆支护理论完善及支护参数选取具有一定实用价值。

In order to study the conversion law between pre-tightening torque and pre-tightening force of rock bolts,the main control factors of conversion efficiency were systematically studied through theoretical analysis and on-site experiments.Based on numerical simulation results,the parameters of pre-tightening torque were optimized.The research results indicate that,under the same pre-tightening torque,as the friction factor between the nut and thread and the friction factor between the nut and washer increase,the pre-tightening force of the rock bolts decreases,and the reduction rate shows a decreasing trend.For fine-tooth fully threaded rock bolts and left-hand non longitudinal reinforcement rock bolts,when the pre-tightening torque exceeds 400 N·m,the increase in pre-tightening force becomes slow as the pre-tightening torque increases,and the pre-tightening force increment obtained by continuing to apply the pre-tightening torque is small.The larger the diameter of the rock bolt,the lower the pre-tightening torque conversion efficiency.The smaller the pitch of the rock bolt,the higher the pre-tightening torque conversion efficiency.When the pre-tightening force reaches 80 kN,the pre-tightening torques for the rock bolts of 18 mm diameter fine-tooth fully threaded and 20 mm diameter left-hand non longitudinal reinforcement are 408 N·m and 429 N:m,respectively.The research results have certain practical value for improving the theory of rock bolt support and selecting support parameters.