Expressway Soft Subgrade Instability Risk Analysis Methods

With the development of the economy, there are more and more highway which was builded on the soft ground, how to evaluation it's Stability become one of Major challenges which we have to confront. The Stability of soft soil embankment is influencd by many factors, and the various factors are interrelated and inseparable. The commonly used evaluation methods of soft soil embankment Stability and safety are based on traditional limit equilibrium principle and some improving methods for the present, such as the Swedish slice method,simplified Bishop method,Janbu method,Morgenstern-Price method etc, these methods are simple and easy to understand, and have been successfully used in many engineering practices. As the traditional limit equilibrium method have been made a lot of simplifying assumption, in some cases, the results obtained were produced a large deviation from the actual. AS there are so many miscellaneous factors influence the Stability and safety of soft soil embankment, considering the variety of factors and engineering practice, this paper introduce Risk Analysis and Evaluation theory to evaluation it's Stability and safety, to construct a set of appropriate and mature safty risk evaluation index system of soft soil embankment, of great theoretical significance and practical economic value.First of all, the dissertation researches Engineering disaster risk assessment and the Failure mechanism of soft base embankment at home and abroad, then discusses the current hot topics and the difficult issues, based on this, the main research contents and paper frame structure are given. The main research includes the following sections:(1) This paper simply discusses the properties of soft soil foundation and the common methods of soft foundation treatment, then soft soil embankment failure modes and the influencing factors are analyzed and summarized. The traditional embankment stability evaluation method of limit equilibrium method and currently using relatively general finite element method are given a contrast introduction.(2) Based on the characteristics of soft soil embankment instability and failure, this paper introduce Risk Analysis and Evaluation theory to evaluation it's Stability and safety, at first, briefly introduced the basic concepts of disaster risk,the process of risk management and the commonly used evaluation methods, then analysis the influence factors of instability and failure of soft soil embankment, as the instability of soft soil embankment is a gradual process of accumulated mutations, this thesis introduced Catastrophe progression method to to evaluation it's Stability and safety.(3)Give a detailed description of the elementary catastrophe theory, then basing on elementary catastrophe theory, the soft soil embankment safety risk evaluation model is established, set up the safty risk evaluation indexs, construction of a safty risk assessment matrix of soft soil Embankment.(4) Using the safty risk assessment matrix of soft soil Embankment to evaluate the stability safety of Shenhai Expressway, and compared the results with the results calculated by Soil management software and Flac slope, which base on limit equilibrium principle and finite element method.The results show that the method of soft soil embankment safety risk evaluation is Reasonable and feasible.