Experimental And Numerical Simulation Research On Impact Factors Of Transport Of Suspended Solids In Pipeline

The water flow and solute transport in karst pipelines have always been a hot topic for Chinese and foreign scholars.Related research has provided technical support for solving the problems of groundwater resources and water environment in karst areas.However,due to the fact that suspended solids are insoluble in water,the main sedimentation in the process of migration is affected by many factors such as the diameter of the karst pipeline,water flow velocity,initial concentration,and particle size of the suspended solids,ect.The law is not clear and the mechanism of the transport of suspended solids in karst pipelines is undefined.All of these have limited the model study of the transport process of suspended solids in pipelines.But in fact,in the karst area of China,the tailing ponds often occur in accident conditions,such as mud and other suspended matters entering the karst pipelines through the sinkholes,thereby threatening residents' domestic water use and affecting the regional water environment.The contradiction between water environment security and weak study on the Mechanism and Model of suspended solids Transport in Pipeline is outstanding.Based on these,the paper carried out an experimental study of different influencing factors of the suspension transport in pipelines.As a result of the complexity of the experimental process,numerous factors,and difficult conditions to control.Through repeated trials and continuous improvement,I designed a new experimental device.A self-priming pump is installed at the head end of the device to provide power for the transport of suspended materials in pipelines,add a valve in the self-priming pump to control the inflow of water(the excess water is returned by the return pipe).Add three valves at the outlet end of the device,simultaneously control the flow rate with the flow meter at the end of the device.The middle part of the device is a PVC water pipe,a plurality of sampling points are set on the water pipe for sampling and monitoring the changes in the concentration of suspended solids at different locations in the pipeline.Using the above experimental device,different experimental schemes were designed to systematically study the effects of factors such as pipe diameter,water flow velocity,initial concentration of suspended solids,and particle size of suspended particles on the settlement of suspended solids in pipelines.The experimental results show(1)Under the condition of the same particle size,flow velocity and initial concentration,the larger the diameter of the karst pipeline,the lower the concentration of suspended matter at the sampling point,and the larger the settlement coefficient K obtained based on the one-dimensional steady water quality model.The sedimentation coefficient increases with the increase of pipe diameter,and it tends to increase nonlinearly.(2)Under the conditions of the same particle size,diameter and initial concentration,the higher the flow velocity in the pipeline,the higher the concentration of suspended solids at the sampling point,the larger the sedimentation coefficient K value.The sedimentation coefficient increases with the increase of the flow rate,and it tends to increase nonlinearly(3)Under the same particle size,diameter,and flow rate,the higher the initial concentration of suspended solids,the higher the concentration of suspended solids at the sampling point,the larger the sedimentation coefficient K value.The sedimentation coefficient increases with the increase of the initial concentration and increases nonlinearly.(4)With the same pipe diameter,flow rate,and initial concentration,the particle size of suspended particles decreases,and the sedimentation coefficient K shows a decreasing trend.The isothermal linear adsorption process was used to characterize the sedimentation.Then the MODFLOW and MT3DMS models in GMS were used to simulate the above experimental results.The simulation results show that there is a same trend between the adsorption coefficient and the sedimentation coefficient,indicating that it is feasible to replace the sedimentation to simulate the suspension transport in the pipeline.This is a quantitative study of the influencing factors of suspended migration in pipelines was conducted,numerical simulation of the migration process under experimental conditions during the study.This study further enriched the theoretical study of solute transport in Karst pipelines and laid a foundation for predicting the impact of suspended matter transport in Karst development areas.It has important theoretical and practical significance.