摘要
在分析研究淄博市大武水源地裂隙岩溶含水层的水力性质和污染物运移特征的基础上 ,对裂隙岩溶水的水头和污染物运移进行数值研究。目前国内外对裂隙岩溶水进行数值计算时 ,通常用等价多孔介质模型 ,但裂隙岩溶介质和多孔介质有很大不同。裂隙岩溶介质的储水和导水空间为裂隙网络 ,导水系数大 ,地下水的实际平均流速比孔隙水大得多 ,但给水度和贮水系数小。当用等价多孔介质模型进行模拟时应考虑这些特点。对于污染物运移的模拟 ,要同时求解水头方程和对流弥散方程 ,可采用MODFLOW和MT3D软件进行模拟。研究区裂隙岩溶水水头的数值计算表明 ,等效多孔介质模型水头的拟合误差能满足国标GB/T144 97- 93的要求。各时段地下水水量均衡计算的精度也满足要求。对流弥散方程的数值计算 ,由于Peclet数高达 95 .6 7,对流占绝对优势 ,可能存在数值弥散和数值振荡 ,因而采用多种方法进行了比较。对于同一问题 ,同时采用上游有限差分法 (UFDM) ,混合的欧拉拉格朗日方法 (特征线法MOC、改进特征线法MMOC和混合特征线法HMOC) ,总变异消减法(TVD)进行计算 ,并比较其结果。结果表明 ,混合特征线法 (HMOC)和总变异消减法 (TVD)比较适合于对流占优势的运移问题计算。由于渗透系数K和有效孔隙度θ对溶质运移结果的影响很大 ,?
Based on the study of the hydraulic properties of fracture karst aquifer and the characteristics of contaminant in Dawu well field in Zibo City, a numerical modeling of fracture karst water head and contaminants transport in the aquifer was studied The equivalent porous media model is widely used as a numerical computation of fracture karst water Nevertheless, there is a great difference between the porous media and the fracture karst media The openings of groundwater flow and storage in fracture karst media are the net of dissolved fractures The transmissivity of fracture karst media is much larger than that of porous media, but the specific yield and coefficient of the storage are much smaller Therefore the velocity of fracture karst water flow is much larger than that of the porous water These properties of fracture karst aquifer must be considered in the numerical modeling The groundwater head equation and the advective dispersive equation should be solved simultaneously in the contaminant transport modeling The software MODFLOW and MT3D have been used in this research The results of numerical computation showed that the fitting error of the modeling produced by equivalent porous media model was less than the demand of National Standard GB/T14497 93 The accuracy of the computation of water balance was also met the requirement The peclet number of the transport is 95 67,which is an average number The transport is an advection dominant problem The numerical dispersion and oscillation may occur in the modeling Several numerical methods, such as upstream finite difference method (UFDM), method of characteristics (MOC), modified method of characteristics (MMOC), hybrid method of characteristics (HMOC) and total variation diminishing (TVD), have been used for the same transport modeling, as well as for comparison of the results TVD and HMOC are proved better than the others The study shows that TVD and HMOC are suitable for the transport modeling Hydraulic conductivity K and effective porosity θ have a great influence on the results of transport However it is difficult to determine the values of K and θ in fracture karst aquifer accurately Therefore, the accuracy of the transport modeling obtained by equivalent porous media model of fracture karst aquifer is lower than that of the water head modeling
出处
《地学前缘》
EI
CAS
CSCD
2001年第1期171-178,共8页
Earth Science Frontiers
基金
国家自然科学基金资助项目! ( 4 9772 162 )
博士点基金资助项目!( 19990 2 842 1)
关键词
裂隙岩溶水
污染物运移
对流弥散方程
数值计算
欧拉-拉格朗日方法
淄博市
fracture\|karst water
contaminants transport
advective\|dispersive equation
numerical computation
Eulerian\|Lagrangian methods
