Predicting The Parameters Of Forchheimer Model About Non-darcy Flow Through The Sandy Gravel In The Yellow River Beach

As Shanxi’s economic development, water resource is becoming arestricting element of local development. Pumping groundwater is widely usedto solve the shortage of water resource. But the difference between the practialwithdrawals and the theoretical withdrawals is too wide. Therefore, the seepagemodel that can precisly calculate the seepage flow is of great importance to thepumping groundwater.This paper took the sandy pebble medium, from the natural accumulationsandy pebble on the middle reach of the Yellow River,as the research object, hascarried on seepage tests of Yellow river original state sandy pebble medium, thesandy pebble medium at the same size and the sandy pebble medium not at thesame level, anaylized the seepage characteristic of the different sandy pebblemedium, obtained the seepage model about non-darcy flow through the sandygravel in the Yellow river and the parameters of the seepage model, anaylizedthe relationship between the seepage model parameters and the physical index ofthe sandy pebble medium not at the same level, carried out trial calculationsabout the predicting model under the different input variables, established theback-propagation network models for predicting permeability and inertialcoefficient based on the coefficient of uniformity, coefficient of curvature andeffective porosity. The research shows that:(1)The linear relationship between the hydraulic gradient and the velocity isno longer valid for the sandy pebble from the Yellow river beach. However, theForchheimer equation can well describe the non-Darcian flow. The seepage characteristic doesn’t well conform to the linear Darcy’s law for the Yellow riveroriginal state sandy pebble medium, the sandy pebble medium whose diameteris between the9cm and the0.01cm the sandy pebble medium whose averagegrain diameter is greater than2mm and the sandy pebble medium not at thesame level.(2)The main factors influencing the seepage model parameters about sandypebble medium are the coefficient of uniformity, coefficient of curvature andeffective porosity, so they can predict the seepage model parameters. Because ofthe different relationship between the main influencing factors and modelparameters, such as power, exponential, binomial relationship, the relationshipbetween the input variable and the predicting variable is complicated nonlinearrelationship. Therefore, the back-propagation network model with complexnonlinear input and output characteristics needs to build.(3)The back-propagation network can well predict the permeability and theinertial coefficient with more than89%predicting accuracy under under thesmaller number of training.The paper studies the non-darcy seepage model parameters models basedon the physical test. The conclusion is important to the pumping groundwater onthe Yellow river beach.