Research On Systems Analysis Methodology For Initial In-Situ Stress Field

Initial in-situ stress field is a complex system interacted by varied factors, and contains interrelating different components such as gravity and structural action, topography and geomorphologic situations, fault and crack geotectonic structures, and geo-mechanical parameters and so on. Property of the system is formed by interaction of the components in the system, which can be influenced and altered due to environment and structure changes of the system, therefore it is very necessary to analyze and research the initial in-situ stress field as a full system.In this thesis, the initial in-situ stress field is analyzed completely as a complex system. Goal and information source of the system were determined and analyzed, respectively, through the systematical research. Affection of the system environment factor and structure on goal effect was revealed by using systematical design, which causes the system environment and goal property further structure standardization, and the behavior feature and effect of the system are reflected by using reasonable and logical design procedure. The system was quantified after mathematical model was established, normal system of the initial in-situ stress field was chosen, feasible plan of structural motion action was conceived, undetermined plan of the system evaluation was determined, future effect of the system optimization was analyzed, and every variety of feasible plans for calculating and analyzing the initial in-situ stress field were sorted by using the systematical evaluation. And finally, reasonable and realer initial in-situ stress field was obtained.The structural motion action is one of main factors for forming the initial in-situ stress field. Evaluation data-base to every variety of feasible plans for constructing the structural motion action and fuzzy membership function for every variety of feasible plans of the system were established, respectively. We present a method using fuzzy evaluation to identify the form (stretch, compression or disturbance) combination and direction of the structural motion actions. Result of the fuzzy evaluation is more well-grounded and reliable than that of experience judgment.We present three methods (i.e. the feasible plans of the system) to obtain the forming factors of the initial in-situ stress field, and each has its own strong points. The first one is an analysis method using multiple equation and variable regression, with which relationship of a group of variables including variable and dependent variable could be considered simultaneously. The second one is a method using gray system theory, with which problem of a few samples of measured in-situ stress value could be resolved. The last one is an optimum method using genetic algorithms, which has the advantages of simplicity, strong robust, quick search speed and strong adaptability.Every variety of feasible plans, supplied to system development, for calculating the initial in-situ stress field were evaluated systematically, which provides a scientific base for choosing the optimum plan. In this thesis, the system was evaluated withweight addition, but the evaluating value needs to be determined by using a united means or scale. In this thesis, a method using neural network to join in the system evaluation is presented to ensure objectivity of the evaluation and the comparable of every variety of plans.One needs to know and demonstrate the value of the initial in-situ stress field at a point or on a section in the engineering. By using neural network method, intelligent expression method of the initial in-situ stress field was presented in this thesis after the expression problem of the initial in-situ stress field was researched. Software for the intelligent analysis and expression of the initial in-situ stress field was programmed, and has the properties of convenience, happy layout of men-machine conversation and easy use in the actual engineering.System idea is well versed in whole system analysis procedure of the initial in-situ stress field...