| Since 1990s,the expressway has developed very quickly in our country. With a rate of about 2 000 km/y, the total mileage of the built expressway has been up to more than 22 500km by the end of 2002, which is the second in the world and exceeds the third one-Canada greatly. However, there are much silt, silty clay, and silt-and-sand bed in the highway grounds of many provinces and cities. Because most of these grounds have high compressibility, great subsidence and bad stability of consolidated drainage, if expressways are built on these grounds without improvement or managed improperly, the quality of roads will fall even destroy. With the building of expressways, the problem of soft ground is becoming more and more protrusive and has been one of key factors influencing project quality, project cycle and project cost. So it has become a very important task to strengthen the research on the improvement of expressway soft ground, which affects the development of traffic project in China.There re many decision problems in the study of expressways ground improvement. During the design phase, decision whether to improve the ground or not should be made firstly, then it should make clearly whether deep improvement or shallow improvement in the segment which needs improvement. And the detailed method on improvement should be made distinctly too. Finally, the technical parameters of the method should be decided. During the construction phase, it should make decision on loading speed according the dynamic supervising results and make decision on the adding spread time of road according the prognostic subsiding result after construction.Owing to various influential factors, a great deal of calculation and imperfect design theory, experience always plays an important part in the technical decision of ground improvement. Therefore, how to make the technical decision of ground improvement more scientific becomes very important. Based on project practice of expressway ground improvement in recent ten years, this article deeply studies many decision problems of expressway ground improvement, makes definitesome existing subjects which should be resolved in the decision of expressway ground improvement currently. Theoretically based on system engineering, artificial intelligence, knowledge engineering, comprehensive evaluate, neural net, fuzzy mathematics, genetic algorithm, decision analysis, computer technology and so on, and combined with the latest developments of geo-technique and soil mechanics, it studies many aspects of problems to establish intelligent decision support system of expressway ground improvement, explores helpfully intelligentization and scientificalization of decision of expressway ground improvement, replenishes the blank of this field.According to the research contents and sequences of chapters and sections, this abstract introduces concisely as follows:1. It expresses briefly the purpose and significance of the article, and introduces comprehensively present research situation, existing problems and research prospect of ground improvement. Based on systems analysis of decision problems of expressway ground improvement, it puts forward research subject and chief contents of intelligent decision support system of expressway ground improvement.2. Artificial neural net (ANN) is used in technical decision of expressway ground improvement for the first time. And ANN model is setting up by usingANN Toolbox which the advanced calculation tool--MATLAB provided. Keyfactor is found out by analyzing deeply the influential factors of ground improvement, and decision models of two parameters and five parameters are set up. By collecting practical data and making experiments on ANN models, the result proves that ANN decision models are valid.3. It uses the MATLAB-FIS for the first time to create the fuzzy decision model on the ground improvement of expressway. It also analyses the influential factors of ground improvement, finds out the key factors, and makes the filling height, the thic...
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