四川广巴高速公路红层滑坡成因分析及防治措施

Analysis of cause and treatment measures for a landslide in red mudstone in Guangyuan-Bazhong expressway

四川北部山区高速公路红层滑坡灾害广泛存在。根据广巴高速公路木门段滑坡的现场勘查,从地形地貌、地层岩性、地质构造、水文地质及滑坡形态等方面对滑坡形成机制进行分析,指出该滑坡属滑移—牵引型滑坡。通过对滑坡稳定性分析计算,得出其稳定系数K在1.05～1.15,且滑坡前缘在河床中,洪期受河水冲刷,加之匝道路堑和桥梁基坑开挖均对滑坡稳定不利,其稳定系数正逐步降低,处于欠稳定—基本稳定状态,需进行处治。结合工程实际,提出了于二级滑体前部设置抗滑桩、一级滑坡后部设置小直径钢管排桩,并辅以排水、截水设施的防治措施。

Red bed landslide disaster is widespread to the Northern mountainous expressway in Sichuan province. According to the field exploration on Guangyuan-Bazhong expressway, the formation mechanism of landslide is analyzed through landforms, rock character, geologic structure, hydrological geology and landslide morphology, so the type of the landslide is proved to be sliding-traction. Through the analysis and calculation of the landslide, the stable coefficient K ranges from 1.05 to 1. 15, the front part of the landslide is in river bed which suffers flood flushing, and the ramp cutting and foundation pit excavation is harm to the landslide stability, which causes the decrease of stable coefficient in to a critical state, so the landslide needs to be reinforced. Combined with the engineering practice, treating measures are putting forward which are piles setting to the front part of secondary landslide, small diameter steel pipe piles setting to the backside of first order landslide, and assisting with draining and intercepting of water.