Research On The Safety Assessment Of Subgrade Slope At Slippery Stratum In Chongqing Three Gorges Area

Large-scale roadbed disasters of Chongqing Three Gorges region,50%developed in the Triassic Badong group, pearl red group of Jurassic and Quaternarycollapse talus formation.Such strata may be collectively referred to as the slipperystratum. During the period of highway construction and operation, the roadbed whichin the formation of class prone to appear disease and even caused instability by thedisaster. Therefore, to the slippery strata the subgrade security evaluation techniques,the smooth implementation of road construction to ensure that the region continue toimprove the economic, social and environmental benefits of highway projects, andhas important practical significance.In this thesis, relying on the Ministry of Transport, the Western TransportationResearch Project of Chongqing Three Gorges region is easy to slip the formationsubgrade slope safety evaluation, forecasting and control techniques, and slipperystratum subgrade slope safety evaluation techniques to carry out the Chongqing ThreeGorges area. The content of the study the following aspects:①papers in the investigation and analysis, based on literature data, combinedwith the basis of previous studies, summarizes and analyzes the Chongqing ThreeGorges area is easy to slip the formation subgrade slope disease type, the geneticmechanism of rock mass characteristics, structural characteristics, geologicalenvironment directly or indirectly affectthe stability of the roadbed. And impactslippery formation embankment slope stability factor is classified as engineeringfactors, geological factors and other factors into three categories, the subgradedeformation is divided into three types of motility and loosening the two types ofinstability and failure mode is divided into the collapse, sliding, and dumping and itsinfluencing factors.Third, the influence of slippery formation embankment slopestability were summarized and analyzed, mainly refer to engineering factors,geological factors and of other factors. And embankment slope stability instabilityincludes the two forms of common slip strata deformation and instability. By analysisloose accumulation within the stability, concludes the rock’s physical and mechanicaleffects, geological, environmental and geological features.②step-by-step study on the loose accumulation of body, under normalconditions and non-normal operating conditions Ⅰ (normal working conditions, loadonly consider the slope body weight, the slope weight calculated by the natural weightdegree; non-normal working conditionsⅠ and load only consider the weight of theslope, under heavy rainfall conditions, the slope of body weight calculated accordingto the saturated severe.) the combination of qualitative evaluation and quantitativecalculation using the limit equilibrium theory and the unbalanced thrust calculation.The result is consistent with the actual project, provides a theoretical basis andpractical guidance on the actual project.③Fengjie to Wuxi Highway E4Contract Section of the loose deposits subgradeslope, for example, the use of PLAXIS8.5finite element software, the accumulation slope stability of the status quo, the influencing factors, deformation characteristics,and control measures carried out a comprehensive, the system is calculated.Comparative analysis and numerical simulation and theoretical calculations, theresults are basically the same, the error is very small, in line with the practicalengineering.Papers in the Safety Evaluation of subgrade slope of slippery stratareference value.