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The Hydraulic Performance of Perforated Pipe Under-drains Surrounded by Loose Aggregate

出版	Clemson University, 2013
URL	http://books.google.com.hk/books?id=8SiGngEACAAJ&hl=&source=gbs_api

註釋Abstract: Perforated pipes are commonly used in the construction industry for subsurface drains. These subsurface drains are installed to intercept and convey infiltrated runoff or groundwater. One common application of perforated pipe is to provide an under-drain for an infiltration trench or porous pavement best management practice (BMP). Perforated pipe is installed into a trench on a bed of aggregate ranging from 0 to 28 cm thick and, depending on the design objective, is laid flat or on a slope. However, the actual hydraulic performance of these pipes, i.e. the stage storage relationship, is poorly understood. The resulting flow is quite complex with porous media flow through the aggregate, multiple orifice flows into the pipe and pipe flow with lateral inflow along the length. This thesis presents results of an experimental investigation of the relationship between the height of water above the pipe, and the resulting discharge for a trench filled with aggregate that is fed with water from one end. The pipes tested were leached and perforated, for both 10.2 cm and 15.2 cm diameters. The pipes were tested for three different trench widths filled with 28 cm of #57 Stone. Three samples of each pipe size and type were tested with flow rates ranging from 0.002 - 0.018 m3/s. Two main flow types were observed, saturated, in which the aggregate layer is fully covered, and unsaturated, in which the free surface of the water is below the aggregate surface. Head discharge relationships for both conditions are presented. These results will enable design engineers to model the hydraulic behavior of under drained infiltration systems. This, in turn, will enable accurate routing of design storms through a range of low impact development (LID) and BMP technologies such as porous pavements and infiltration trenches.