| Due to the complexity of hydrogeological conditions and the limited investment in hydrogeological survey,the uncertainty of hydrogeological parameters in groundwater numerical simulation will be caused,which will affect the reliability of groundwater numerical simulation results.The research on groundwater uncertainty at home and abroad is mainly based on random probability and statistical methods.Random methods need to count the probability distribution characteristics of uncertain parameters.However,due to the lack of sufficient sample data,it is difficult to obtain accurate probability distribution characteristics of parameters.Based on the first-order interval parameter perturbation method,this thesis proposes a two-dimensional groundwater head interval response method,which is realized by the groundwater flow numerical simulation program GFModel.This method can calculate the interval of the water head under the condition that the hydrogeological parameter interval is known（the interval is composed of the minimum and the maximum）.The main work and conclusions of the thesis are as follows:（1）The relevant hydrogeological data of the hydrogeological test site in Nanhu Campus of China University of Mining and Technology in Xuzhou City were collected.A single-hole complete well unsteady flow pumping test was carried out for the phreatic aquifer.One pumping well and nine observation wells were set up.The pumping time was 5400min（3.75d）,the water level recovery time was 1660min（1.15d）,and the total test time was 7060min（4.9d）.Nine sets of head data,one set of flow data,and precipitation data during the test were measured.（2）Two-dimensional groundwater flow head interval response method based on first-order interval parameter perturbation method（FIPPM）is proposed and implemented by the groundwater flow numerical simulation program GFModel.In order to verify the effectiveness of the method,an ideal model of two-dimensional steady flow and unsteady flow is established.According to different scenarios,the error analysis is carried out between the head interval calculated by the method and the head interval calculated by the equidistant continuous sampling method（theoretical method）.The error analysis of the calculated head interval shows that when the change rate of the interval parameter is below 0.2,the relative error of the head extreme value does not exceed 2%.It is proved that the proposed method has better accuracy and higher computational efficiency than the equidistant continuous sampling method when the change rate does not exceed0.2.（3）The hydrogeological conceptual model and deterministic groundwater flow numerical model of the test site are established.On this basis,the interval groundwater flow numerical model is constructed,and the parameter interval of the model in the study area is given.The permeability coefficient interval is[1.125m/d,1.725m/d],the adaptive flow boundary permeability coefficient interval is[0.75 m/d,1.15 m/d],the reciprocal of the adaptive flow boundary distance is[0.0075m-1,0.0115 m-1],and the initial head interval is[9.9m,10.1m].The specific yield interval is[0.0075,0.0115],and the constant head interval is[9.8m,10m].The calculation results show that when the model parameters are inaccurate or uncertain,the head interval calculated by the method in this thesis can better contain the measured head,which has a certain guiding role in the application of groundwater numerical simulation in practical engineering.This thesis has 38 figures,24 tables,and 114 references. |
