Research On Foundation Pit Dewatering Based On AEM And Fuzzy Decision Method Analysis

Analytic Element Method is a new technique which describes every kind of groundwater hydraulic element as analytic element; and it is convenient to solve complex groundwater problems; and it is the only technique which can combine the traditional analytic method with numerical method. Groundwater flow in a single aquifer. GFLOW is groundwater problem analytic software which based on Analytic Element Method. As using the constructive character of Analytic Element Method(AEM), it is convenient to solve complex groundwater problems according to amend every kind of elements and combine every kinds of element .In this paper from the application of GFLOW model groundwater theory and method are assimilated ;and the basic conception and construction of Analytic Element Method(AEM) is studied; and also taking the hydraulic problems of precipitation during excavation of deep foundation pit in XingLong hydraulic project as the background; using the GFLOW model which solves the quantitative analysis and optimization decision in groundwater .The detail contents are the following:(1)Review the basic equations of groundwater movement, then from the basic conception of potential obtaining the basic equation, and then obtaining the analytic element of well, on the base of which the line-sink model and the line-doublet model were deducted.(2)Based on theory foundation above, choosing the foundation pit dewatering in XingLong hydraulic project, directing toward the situation of project, according to the computing characteristic of AEM, the feature of the aquifer was generalized, the element of the line-sink which symbolized the fixed water lever and the line-doublet which symbolized the cut-off wall were generalized; and then the mathematic model was established.(3) According to make the sensitive analyze about the hydraulic coefficient and the compare with the GMS model, about the single aquifer generalization the precision can meet the demand of engineering. From the research about seepage control measure and the result the it was deducted that in the deep sand layer the effect of the hang cut-off wall is limited; and it accorded with the objective rule of general; and it was further proved that the GFLOW model accorded with the objectivity. Using the parameters the hydro-isobaric line in nature situation was computed, which reasoned the necessity of dewatering. According to adjust the distance of well, the flux of every well, the location of the well, the reasonable combination of model was obtained, which provided the available chosen case for the next multi -target fuzzy decision.(4) According to introduce the conception of Multi -target fuzzy decision - making, mathematic model was established, the control target in precipitation during deep foundation pit was proposed and analyzed, according to analysis the importance contrast, weight vector of the target was obtained, finally the decision vector was obtained, which provide the optimized decision for the foundation pit dewatering in XingLong hydraulic project.