Equivalent Parameter Model Research For Suspended Matter Migration Problem In Karst Pipeline

The study on the migration of pollutants in the underground underground river in the karst development area has been a hot and difficult point in the related research.The equivalent porous media model is the most mature,and the calculation software based on this model is also the most involved,and it is widely used to simulate the flow and solute transport of karst river.However,for the simulation of the migration process of suspended matter in karst pipelines,the equivalent porous media model has been limited by the lack of parameters that can describe the sedimentation process during the migration of suspended solids.It is important to study the numerical simulation model of equivalent porous media which can replace the suspended matter of suspended matter.Based on the similarity between the adsorption coefficient and the sedimentation coefficient in the process of the reaction solute transport in the current equivalent porous medium,the factors affecting the sedimentation coefficient and the adsorption coefficient are discussed.The relationship between the adsorption coefficient and the sedimentation coefficient under different conditions is studied.The isoparametric substitution model is applied to the karst area in Guangxi.At present,the results of one-dimensional steady-state water quality model of commonly used rivers simulated by the migration of suspended matter in karst underground are compared.Finally,the parameters of karst area are difficult to obtain,which leads to a large uncertainty problem,and parametric sensitivity and model uncertainty analysis of isoparametric substitution model.Get the following conclusions:(1)At present,the commonly used groundwater numerical model and software can simulate the sedimentation coefficient in the process of migration of suspended pollutants in the karst pipeline.(2)The indoor experiments show that the factors affecting the sedimentation coefficient and the adsorption coefficient are the particle size and initial concentration of the suspended matter,the diameter of the karst pipe and the groundwater flow rate.The sedimentation coefficient and the adsorption coefficient are inversely proportional to the particle size of the suspended matter,the initial concentration and the groundwater flow rate.The sedimentation coefficient and the adsorption coefficient are inversely proportional to the diameter of the karst pipe.When the other conditions are the same,the sedimentation coefficient and the adsorption coefficient are independent of the migration distance.The experimental results provide a reference for the future setting of the adsorption coefficient in the simulated karst pipeline.(3)Based on the experiment,the corresponding settlement coefficient and adsorption coefficient under 10 kinds of experimental conditions are obtained,and the settlement coefficient and the adsorption coefficient can be directly used to simulate the same condition.(4)The isoprocessing model successfully applied to the example.Compared with the commonly used one-dimensional steady-state water quality model,the isoprocessing model considers the hydraulic exchange between the karst pipeline and the surrounding fissure groundwater,and it is more reasonable to simulate the migration of suspended pollutants in karst pipelines.(5)The parametric sensitivity analysis of the algebraic algebraic numerical model is carried out.The results show that the first three parameters with large influence on the numerical model are the converted permeability coefficient,the equivalent adsorption coefficient and the longitudinal dispersion.Therefore,in the construction of deterministic model,we must carefully consider the selection of these three parameters.