大地电磁法结合FLAC 3D在路基穿越大型古滑坡体稳定性分析研究

Study on Stability Analysis of Expressway Crossing Large Ancient Landslide

山区高速建设不可避免会穿越古滑坡体,对路基稳定性造成影响。为研究路基穿越古滑坡体可行性,依托广西某高速公路穿越大型古滑坡处治项目,通过现场钻探法、音频大地电磁物探法获取滑动体范围,采用数值分析法对古滑坡体路基稳定性进行计算分析,对稳定性差的路段采取措施进行加固,结果表明:视电阻结果与钻孔结果较为相近,可作为古滑坡体范围判定方法(古滑坡体判定依据);古滑坡体内部节理裂隙发育,岩体破碎,水沿裂隙进入导致视电阻低阻异常,深度0.00~30.00 m,电阻值为0~150Ω·m,为古滑坡周界范围;根据音频大地电磁法探测古滑坡体范围,利用FLAC 3D中的interface单元模拟古滑带松散土体,能够较好地模拟古滑坡体所处的稳定状态;进一步模拟分析不同道路设计工况对古滑坡体稳定性影响,采用抗滑桩或宽平台卸载及锚固、排水等方法进行防护。结果可为类似工程提供参考。

The construction of high-speed highways in mountainous areas will inevitably cross ancient landslides,which will have an impact on the stability of the roadbed.In order to study the feasibility of roadbed crossing ancient landslide,this article relies on a large-scale ancient landslide treatment project of a certain highway in Guangxi.The sliding range is obtained through on-site drilling method and audio magnetotelluric geophysical exploration method.Numerical analysis method is used to calculate and analyze the stability of the ancient landslide roadbed.Measures are taken to reinforce the sections with poor stability.The results show that the apparent resistance results are relatively similar to the drilling results,it can be used as a method for determining the range of ancient landslide bodies(the basis for determining ancient landslide bodies);the internal joints and fissures of the ancient landslide are developed,the rock mass is broken,and water enters along the fissures,causing low apparent resistance anomalies.The depth is 0.00~30.00 m,and the resistance value is between 0~150Ω·m,which is the boundary range of the ancient landslide;based on the audio magnetotelluric method to detect the range of ancient landslides,the interface unit in FLAC3D is used to simulate the loose soil in the ancient landslide zone,which can better simulate the stable state of the ancient landslide;further simulate and analyze the impact of different road design conditions on the stability of ancient landslides,and use anti slip piles or wide platform unloading,anchoring,drainage and other methods for protection.The results can provide reference for similar projects.