高海拔深厚覆盖层库区公路变形破坏特征及防治措施研究

Research on Deformation and Damage Characteristics and Prevention Measures of Highway in High Altitude Reservoir for Deep Overburden

2018年强降雨诱发西藏高海拔深厚覆盖层库区公路变形破坏,加之库水的浪蚀作用,使深厚覆盖层库区公路路基变形破坏加剧。现场调查研究得出,库区公路变形破坏区域主要分为坡顶拉张区、临水面淘蚀区和坡内剪切-滑移区,变形破坏过程包括路面裂隙孕育阶段、路面裂隙加剧阶段和路基剪切-滑移阶段,整个库区公路以拉张-剪切破坏为主。以此为依据,防治措施主要针对库区公路拉张破坏和剪切破坏展开。其中坡面拉张破坏区周边采用截水沟、回填裂缝等措施进行处理,公路两侧设计边沟排水;剪切破坏应以压坡脚为主,防淘蚀为辅。经库岸塌岸预测,建议以库岸稳定性线为坡率设计依据,清除库岸稳定性线以上不稳定坡积块碎石,临水坡面设计干砌石护坡,下部设计一定厚度和满足级配要求的反滤层,对垮塌路基区域做回填处理。

In 2018,deformation and damage of highway in Tibet's high-altitude reservoir area for deep overburden was induced by a heavy rainfall.In addition,wave erosion of reservoir water intensified the deformation and damage of highway subgrade in the deep overburden reservoir area.According to the field investigation,the deformation and failure of the highway in the reservoir area are mainly the tension area at the top of the slope,the washout area near the water surface and the shear slip area in the slope.The deformation and failure process includes the incubation stage of the pavement cracks,the aggravation stage of the pavement cracks and the shear slip stage of the subgrade.The whole highway in the reservoir area mainly suffers the tension shear failure.On this basis,the prevention and control measures are mainly aimed at the tension failure and shear failure of the road in the reservoir area.Among them,intercepting ditch,backfilling of crack and other measures shall be taken around the slope tension damage area,a nd side ditches shall be designed on both sides of the road for drainage;the shear damage shall be mainly caused by pressing the slope toe,supplemented by anti-scouring.According to the prediction of bank collapse,it is suggested to take the stability line of the bank as the basis of slope rate,remove the unstable slope accumulation block gravel above the stability line of the bank,design dry masonry slope protection on the slope near the water,design a certain thickness of filter layer at the lower part and meet the grading requirements,and backfill the collapsed subgrade area.