山区输电塔滚石撞击响应分析及撞击力计算

Response Analysis and Simplified Calculation of Impact Force of Transmission Tower in Mountain Area under Rolling Stone Impact

输电线路穿越复杂山区和不良地质区域时极易受到侧方滚石撞击。为了掌握滚石撞击作用下山区输电塔受力特性,以某山区800 kV特高压输电线路T型输电塔为对象,采用非线性显式动力学方法,建立了输电塔滚石撞击有限元模型,研究了输电塔撞击区域杆件变形、应力及其时程变化,分析了滚石撞击位置、角度、速度以及滚石直径对输电塔撞击响应的影响规律,给出了输电塔滚石撞击力峰值计算公式,并与其他算法对比验证。结果表明:输电塔滚石撞击力呈现三角脉冲形态,持续时间短、冲击力大;输电塔撞击区域塔杆变形和内力较大,撞击时塔杆应力水平瞬时达到峰值,随后迅速振荡衰减,并逐渐稳定;滚石撞击后塔杆发生塑性变形,出现残余应力,但残余剪应力水平小于残余轴向应力;滚石撞击位置处于1/6~1/8塔高时,滚石撞击力峰值和杆件的残余轴向应力相对较大,撞击角度为0°时,输电塔的撞击响应最为剧烈,撞击速度和滚石直径对输电塔撞击响应影响较大;撞击力峰值拟合公式可用于输电塔滚石撞击力的估算。

When the transmission line passes through complex mountainous areas and unfavorable geological areas,the transmission tower is very vulnerable to lateral rolling stones.In order to master the dynamic response characteristics of transmission tower in mountainous area,taking the T-shaped transmission tower of 800 kV ultra high voltage(UHV)transmission line in mountainous area as the object,the finite element model of transmission tower rolling stone impact was established by using nonlinear explicit dynamic analysis software.The rod deformation,stress and time history change in the impact area of transmission tower were studied.The effects of rolling stone impact position,velocity,angle and mass on the impact response of transmission tower were analysed.The calculation formula of peak impact force of rolling stone of transmission tower was given and compared.The results show that the rolling stone impact force of transmission tower presents a triangular pulse shape,with short duration and large impact force.The deformation of auxiliary materials in the impact area of transmission tower is large,and the stress of its rod is the most unfavourable.During the impact,the stress level of the tower rod reaches the peak value instantaneously,then oscillates and decays rapidly,and gradually tends to be stable.After the impact of rolling stone,the tower pole undergoes plastic deformation,and the residual axial stress level of the tower pole is greater than the residual shear stress;When the impact position of the rolling stone is 1/6 to 1/8 tower height,the peak impact force of the rolling stone and the residual axial stress of the rod are relatively large.When the impact angle is 0°,the impact response of transmission tower is the most severe.The impact velocity and rolling stone diameter have great influence on the impact response of transmission tower.The peak value fitting formula of impact force can be used to estimate the impact force of rolling stone of transmission tower.