Study On Intelligent Evaluation And Optimization Methods Of The Soft Ground Improvement Of The Expressway

With the large-scale construction of expressway, 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 are much decision problems in the study of expressway soft 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. Based on system engineering, artificial intelligence, comprehensive evaluation, neural network, fuzzy mathematics, genetic algorithm and particle swarm optimization, etc. and combing the latest developments of geo-technique and soil mechanics, the dissertation studies many aspects of problems to establish intelligent decision support system of expressway ground improvement.According to the research contents and sequences of chapters and sections, the main achievement of the dissertation are concisely mentioned 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 model of soft soil improvement methods.2. In view of the incompleteness and uncertainty of these effective factors, a new intelligent decision model of the soft ground improvement method of the highway using case-based reasoning is presented for the first time. Considering the sensitivity of attribute weights to the environment, the algorithm of attribute weights is set up on the basis of the concept of changeable weights. It is shown from example that results of the decision model is simple, visual, practical and convenient to use. 3. In this dissertation, the decision model of the soft soil improvement methods based on fuzzy analogy preferred ratio is put forward. In this model, fuzzy analogy preferred relationship between feasible methods and the ideal one is determined, and the similar series in them in every affecting factor is given. Determining their factor weights by using the analytic hierarchy process (AHP), the comprehensive similar series in them is carried out, and the most similar soft ground improvement method to ideal one is found out. It is discussed how to choose the input parameters of the decision model. Using the MATLAB-NNT, a decision model of the soft soil improvement of the expressway with 4 parameters is established. After trained by input data and target data, recollected by same data and simulated by new input data, the result of the model is satisfied, and the model is effective.4. In view of the uncertainty of index for evaluating soft ground improvement programs, combining with fuzzy matter-element method and the entropy value theory, the fuzzy matter-element model is established based on entropy value theory. The weights are calculated according to the method of information entropy indicating the availing value of data, and the problem of weight allocation is solved. The model is applied for programs evaluation of improving expressway soft ground and a reasonable program is got which provides a new way to select programs for improving soft ground.5. The factors that affect the decision of soft ground improvement method have the features of incompleteness and uncertainty, making a decision of the soft soil improvement methods is a Grey System Theory problem essentially. By means of Grey system theory, the new decision model is established. In this model, the evaluation indexes of the schemes and their weights are reasonably decided; the optimal scheme is selected by calculating the relational grade to attain the selection and order arrangement for the schemes. The results of the actual examples indicated that the decision model is reasonable, valuable and it is convenient to use.6. Adaptive resonance theory is used in technical decision of expressway ground improvement. Decision model based on adaptive resonance theory is set up for the first time. The result proves that the model is valid and easy to realize.7. The basic design computational process theory of dry jet mixing pile is studied. Three optimization models are set up based on the genetic algorithm, particle swarm and nonlinear theory for dry jet mixing pile, and the optimization design system of dry jet mixing pile is programmed. Finally, the results of the actual examples indicated the validity and feasibility of the two optimization methods.