Research On Surface Deformation Monitoring And Early Warning Technology Of Service High Slope For Expressway In Mountainous Area

Aiming at the key technical problems such as high slope deformation monitoring and instability early warning,relying on the two typical high slope projects in service of mountain expressway in Anhui Province,the joint monitoring of slope surface deformation is carried out by using new technologies combined with global navigation satellite system(GNSS),UAV close-range photogrammetry and total station geodesy;Based on the numerical simulation of seepage field and slope stability and the analysis of typical cases,a multi index early warning empirical threshold model is proposed,and the corresponding deformation monitoring and early warning system is developed,in order to provide theoretical and technical support for the disaster prevention and instability early warning of operating Expressway Slopes in Mountainous Areas.1)Combined with the self-developed multifunctional target,the error influencing factors of GNSS and UAV close-range photogrammetry accuracy are analyzed through outdoor tests.The results show that the coordinate error of GNSS can be reduced by prolonging the difference time,and the average coordinate mean square error of 24h difference time is 4.1mm;The measurement error of UAV close-range photogrammetry can be reduced by reducing the photographing height and selecting medium light intensity.The coordinate mean square errors of photographing height 20m and illuminance 77Btu/(ft~2·h)are 1.7mm and 0.9mm respectively.Based on this,the joint monitoring technology scheme of slope surface deformation is proposed.Compared with the traditional monitoring technology,this technology has the advantages of multi means,convenience and economy.2)The monitoring scheme of two high slopes in service relying on the project is designed,multi-functional targets are arranged,and the joint monitoring technology is used to monitor the slope surface deformation in two phases.The results show that the joint monitoring technology can effectively monitor the slope surface deformation in the high slope project in service,and small local deformation occurs in both slope surfaces.3)GeoStudio and FLAC3D software are used to analyze the seepage field and fluid solid coupling steady state of the high cutting slope of the supporting project.The results show that when the rainfall intensity reaches 250mm/d,the slope will produce a shear sliding surface and lose stability.A multi index empirical threshold early warning model based on precipitation intensity,cumulative displacement and displacement rate is proposed,and the slope instability risk is divided into four levels.The prediction of the model shows that the two slopes are in the stage of uniform deformation,and the probability of instability failure in a short time is low.4)According to the slope monitoring scheme and early warning theory,an early warning system based on the deformation monitoring of the high slope in service is developed.The system has been successfully applied to the phase II deformation monitoring of the high cutting slope in service relying on the project,which can meet the basic needs of monitoring data processing and instability early warning in the later stage of the actual project.In summary,a joint monitoring and instability early warning technology of slope surface deformation proposed in this paper can be used as a reference for the application of high slope engineering of operating Expressway in mountainous area.