高风险落石运动分析及边坡防护综合设计

Analysis of Highly Risky Rockfall Movement and ComprehensiveDesign of Slope Protection

中越边境某高速公路面临严峻的高位山体落石风险,常规防护方案难以奏效,为解决落石隐患,通过数值模拟方法分析落石运动规律,提出防护设计方案。研究得到以下认识:①对于落石冲击能远超工程措施防护能级的情况,应高度重视坡型设计,引导落石沿可控的轨迹运动、碰撞减速消能;落石与宽平台及落石槽碰撞后能量衰减率可达到80%以上;②坡顶挖方线与自然坡切线角度α越小,越有利于引导落石贴坡坠落;③内倾落石槽具有优越的落石滞留和能量衰减效果,但弹跳轨迹较复杂,可配合较高的低能级被动网使用;宽平台的优势在于运动轨迹规则、弹跳高度较小,可配合较矮的高能级被动网进行使用;④废弃土作为缓冲垫层能显著提高落石防护能力,还能缓解弃土造成的环境污染,种植绿化后尚有美化景观的作用。研究思路及成果可为落石防护提供借鉴和参考。

A highway on the border between China and Vietnam is faced with severe risk of rockfall from high mountain,and conventional protection scheme is hardly effective.To solve this problem,the movement law of rockfall is analyzed via numerical simulation and protection design scheme is put forward.The conclusions are as follows:1)When the impact energy of rockfall far exceeds the protection capacity of engineering measures,great attention should be paid to slope design to guide the rockfall to move along controllable trajectory and reduce the energy by collision.In this research,the energy attenuation rate of rockfall after collision could reach over 80%by wide platform and rockfall trough.2)The smaller the angle between the excavation line at the top of the slope and the tangent line of the natural slope,the more conducive it is to guide the falling rock to fall along the slope.3)Due to complex rockfall movement track,the inward sloping platform can be used together with higher low-energy passive protection net despite its excellent rockfall retention and energy attenuation effect.Wide platform could generate regular rockfall trajectory and low bounce,hence can be used with lower high-energy level passive protection net.4)Using waste soil as cushion could remarkably improve the effect of rockfall protection and alleviate environmental pollution,and also could beautify the landscape after planting.The research ideas and results provide reference for rockfall protection.