滚石对棚洞结构的冲击动力分析

以棚洞结构为原型,对滚石冲击作用下棚洞的接触力、位移、损伤与能量进行了研究。将滚石简化为刚性球体,围岩和土体为理想弹塑性材料,混凝土为弹塑性材料,通过ABAQUS有限元,模拟了不同速度与冲击角度下滚石冲击荷载对棚洞结构的动力响应。分析结果表明:在冲击角不变时,滚石速度越大产生的位移越大,在速度不变时,滚石的冲击角越小产生的位移越大;混凝土防护结构损伤最严重的地方发生在与滚石接触的区域,其次在斜腿柱上端和同柱子连接的横梁处,在实际工程中应加强柱子上端与横梁连接处的强度;棚洞主要通过混凝土防护结构来吸收和消耗冲击能,土垫层吸收和消耗冲击能很有限,为了缓解滚石冲击对混凝土防护结构的破坏,可在棚洞支座处增设耗能减震器。

Dynamic analysis of rock-fall impact on shed tunnel structure

Shed tunnel structure was taken as prototype,and the contact force,displacement,damage,and energy of shed tunnel under rock-fall impact were studied.Rock-fall was simplified to rigid sphere,surrounding rock and soil were reduced to ideal elastic materials,and concrete was regarded as elastic-plastic material.The dynamic responses of rock-fall impact on shed tunnel structure at different speeds and incident angles were simulated by using ABAQUS finite element.Analysis result shows that when incident angle is unchanged,the greater rock-fall speed is,the greater the displacement is.When rock-fall speed is constant,the smaller rock-fall incident angle is,the greater the displacement is.The worst damage of concrete protective structure occurs at rock-fall contact area,the second damages are inclined leg pillar top and beam in connection with pillar,and the intensities of pillar top and beam joint should be strengthened in practical projects.Impact energy is mainly absorbed and consumed through the concrete protective structure of shed tunnel,the absorption and consumption of soil cushion layer are very limited.To alleviate the damage of rock-fall impact on the concrete protective structure,energy shock absorber can be added at shed tunnel bearing place.