Modeling Groundwater Flow With Flow Nets Purpose 2765481

MODELING GROUNDWATER FLOW WITH FLOW NETS PURPOSE: Become familiar with a graphical method for modeling groundwater flow through well defined boundaries. OBJECTIVES: Construct a vertical cross-section flow net to determine groundwater flow under a dam and to calculate uplift pressure on the dam. PROCEDURE: Before beginning the flow net problems, read through the material below on flow net construction, with guidelines and suggestions for making a flow net. FLOWNET CONSTRUCTION Although the following procedures are more or less sequential, be certain you read through and understand all the procedures and suggestions before you begin to actually construct a flow net. 1. Ensure that the use of a flow net is valid. (a) Flow is steady state. (c) Boundary conditions are known or can be approximated well. 2. Prepare for a trial-and-error solution: there is no unique solution. 3. Ensure that the boundaries of the flow field are drawn to scale. 4. Define the boundaries, and determine the nature of each boundary Document Preview:

Geotechnical Engineering MODELING GROUNDWATER FLOW WITH FLOW NETS PURPOSE: Become familiar with a graphical method for modeling groundwater flow through well defined boundaries. OBJECTIVES: Construct a vertical cross-section flow net to determine groundwater flow under a dam and to calculate uplift pressure on the dam. PROCEDURE: Before beginning the flow net problems, read through the material below on flow net construction, with guidelines and suggestions for making a flow net. FLOWNET CONSTRUCTION Although the following procedures are more or less sequential, be certain you read through and understand all the procedures and suggestions before you begin to actually construct a flow net. 1. Ensure that the use of a flow net is valid.(a) Flow is steady state.(c) Boundary conditions are known or can be approximated well.2. Prepare for a trial-and-error solution: there is no unique solution.3. Ensure that the boundaries of the flow field are drawn to scale.4. Define the boundaries, and determine the nature of each boundary.(a) equipotential, or constant-head, boundary(b) flow line, or no-flow, boundary: commonly an impermeable boundary(c) known-head boundary; commonly the water table(d) most often encountered, two equipotential boundaries and two flow line boundaries.5. Determine the symmetry of the flow field, if any. This may reduce the work involved-forexample, bilateral symmetry would require construction of only half of the flow net.6. Begin iterative construction of flow lines and perpendicular equipotential lines.(a) Draw flow directions at equipotential boundaries.(b) Draw predefined, or boundary, flow lines.(c) Visualize the number of flow lines that provide a smooth transition between the boundaryflow lines.(d) You will draw only a few of these, perhaps two or three.Geotechnical Engineering7. A fundamental requirement of a flow net is that flow in each of the flow tubes must be equal.Thus, because tubes that are longer…

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