高陡路堑岩质边坡潜在落石灾害评估及防护建议

Evaluation of Potential Rockfall Hazards on High,Steep Rock Cutting Slope and Protection Suggestions

为评估高陡路堑岩质边坡潜在落石的危害风险,以连云港中云台山人工开挖高陡岩质边坡为研究对象,通过地质调查及结构面分析,识别出研究边坡危岩破坏机制主要为风化破坏、平面滑动破坏、楔形体破坏和倾倒破坏,并据此确定了3个潜在落石源区及可能运动剖面。结合现场实际工况特征,基于原位试验测定了运动剖面所涉及的5种坡面材料(坚硬变粒岩、变粒岩散在覆盖较低植被、常态混凝土、喷射混凝土及沥青路面)的法向和切向恢复系数,分别为0.39、0.44、0.47、0.51、0.42和0.84、0.78、0.85、0.88、0.92。综合上述参数,采用RocFall V.4.0程序对研究边坡进行落石灾害分析及防护措施测试。结果表明:无防护措施下,3个剖面上57.7%~61.6%的落石可侵入公路,最大回弹高度可达23.52~26.52 m;随下落高度增加,落石平动速度及总动能呈显著增大趋势,在高速公路区域各剖面落石速度均大于24 m·s^(-1),最大总动能可达1252.4~1711.3 kJ。现有防护措施下,95%的落石被第一、二道防护网拦截,仅存在少数落石逃逸,对超防护能级落石,现有措施可能面临挑战,加强巡视、铺设高吸能材料及原地支护或分解可能有助于该问题的解决。相关研究思路及获得的结果可为类似工程边坡落石灾害风险减轻及防护措施构建、加强提供重要参考。

To assess the risk of potential rockfall hazards on high,steep,rocky cutting slopes,the artificially excavated high,steep,rocky slope of Zhongyuntai mountain in Lianyungang was taken as the research object.Geological investigation and structural plane analysis revealed that the failure mechanisms of the dangerous rocks on the studied slope were mainly weathering damage,plane sliding failure,wedge failure,and toppling failure.Based on this finding,three potential rockfall source areas and possible rockfall movement profiles were determined.The normal and tangential restitution coefficients for five slope materials(hard granulite,granulite covered by lower vegetation,regular concrete,shotcrete,and asphalt pavement)involved in the motion profiles were determined,based on the actual working conditions,through in situ experiments,with values of 0.39,0.44,0.47,0.51,and 0.42 and 0.84,0.78,0.85,0.88,and 0.92,respectively.Considering these parameters,RocFall v.4.0 was used to analyze the rockfall disaster potential and test the protective measures of the slope studied.The results show that,without protection measures,57.7%-61.6%of the rockfalls on the three profiles could invade the highway,and the maximum rebound heights could reach 23.52-26.52 m.As the falling height increases,the translational velocities and total kinetic energies of the rockfalls significantly increase.In the highway area,the rockfall velocities in all profiles exceed 24 m·s^(-1),with a maximum total kinetic energy of 1252.4-1711.3 kJ.With the existing protective measures,95%of rockfalls are intercepted by the first and second protective nets,with only a small number of rocks escaping.However,for rockfalls beyond the protective level,the existing measures may face challenges.Strengthening inspections,laying high energy-absorbing materials,and in situ support or decomposition could help solve this problem.This research and the results obtained provide an important reference for reducing the risk of rockfall disasters and for constructing and strengthening protective measures on similar engineering slopes.