Research On Seepage Mathematical Model And Calculation Method Of Radial Well

Radial well water output calculation is a theoretical problem puzzling the hydrologyfield for many years. Because seepage flow of radial well is a complex three-dimensionalflow, there are seepage flow and pipe flow in the process of groundwater flow of the radiationwell. The flow pattern has both laminar flow and turbulent flow, and flow conditions areextremely complex, hydraulic conditions are difficult to determine strictly. At present, there isa lack of the accurate method of theoretical calculation for confirming the water output of thewhole radial well, but calculation of the water output is very important for the structure designof radial well, well irrigation planning, the determination of hydrogeological parameters andevaluation of groundwater resources. Therefore, it is important to find out SeepageMathematical Model and Calculation Method base on an analysis of the percolationmechanism of radial well. The main contents of the dissertation are as follows:(1)According to the characteristics of radial well flow field and combining with thepercolation mechanics and mathematics knowledge, In this paper, the equation of thepumping descent curved surface single layer radiant tube with uniformly distribution and theformula of effective radius of groundwater are first constructed.By the measured data ofshaanxi qian county area pumping test, it is proved that the calculated result of the model iscoincide to the measured data. Combining with the equipotential lineand the figure descentcurved surface of radiation Wells, Seepage properties of radiation Wells is analyzed anddiscussed.(2) The various factors influencing the radiation well water yield were analysised; it isdiscussed emphatically on the influence of water yield under interference effect of the tubelength of the tube number, so Radiation tube well interference phenomenon is not only relatedwith the tube number, but also related to the length. Interference phenomenon with pipelength is also related to pipe number, in which the two above factors are closelyinterconnected and there is the mapping relationship among them.(3) The method of correlation analysis is introduced on the radiation drawdown andwater output, and illustrated by linear fitting and polynomial fitting from the instance. Simplemethod for radiation well water output prediction is provided on pumping data.(4) According to the characteristics of the radiation less well test data, and the greysystem theory is a kind of new studies focusing on the system with few data, poor information, and uncertainty question. By identifying development trend of similar or dissimilar degreeamong the system factors, it seeks the law of the system changes according to the generationof processing the original data. The GM(1,2) model has been established by means of greytheory to predict water output.(5) Based on curved surface model of the pumping descent, considered the number andlength of the radiant tube’s disturbing effects on water output calculation, the water outputmodel of the whole radiation well of single radiant tube with uniformly distribution isconstructed, and it is recommended in optimizing lateral configuration and providing the basisfor radial well arrangement. Through analyzing of an experiment example and comparingwith equivalent large-mouth-shaped well method and Jushi formula, we verified that thecalculated result of the model is coincide to the measured data, and the method can be used tocalculate the water output.(6) The approximation function of Theis well function is given basing on the idea ofwell function fitting, When the well function of the independent variables is greater than0.01and less than1.1, the maximum relative error is less than1.33%of corresponding databetween the fitting approximate functional and Theis well function table, so it has very highreplacement accuracy and can meet the practical engineering calculation.(7) Aiming at the present issues of calculating hydro-geological parameter based on theradial well unsteady flow pumping test, Discusses the solving method of phreatic aquiferhydrogeological parameters on the complete penetration of radial well unsteady flow pumpingtest by using an imitation Theis formula, the hydrogeological parameter inversionoptimization model is established; In order to simplify the solving process of the optimizationmodel, and improve the precision of the calculation results, the formula of the theis wellfunction is put forward by optimizing fitting method; we can obtain the hydro-geologicalparameters of the phreatic aquifer by solving coefficients of the regression equation, andprove reasonableness and feasibility of the method through a pumping instance.