Investigation of flow characteristics through box shape culvert combined with broad crested weir

This research investigates the hydraulic characteristics of simultaneous flow over broad crested weir and through box culverts experimentally, as well as identifying the effect of parameters, such as upstream head, length, culvert inlet shape, culvert internal dimension, weir crest height, weir side slope angle, weir width, on the performance of combined structures .By this, it is aimed observe the variation in the discharge coefficient (Cd) of the combined structure. Finally, the equations are derived to estimate the flow rate through the combined structure. For this purpose twelve (12) glass models of combined broad crested weir and box culvert were manufactured and tested in a laboratory flume. These models were divided into four groups based on the box culvert dimensions; each group consisting of three models.The experiments were performed in three stages, flow through the box culvert, flow over the broad crested weir, and flow through both the box culvert, and over the broad crested weir simultaneously. Dimensional analysis was performed to obtain the dimensionless parameters that the discharge coefficient depends on. Discharge coefficient prediction equations as a function of the dimensionless terms were developed using (a) multivariable linear regression and (b) multivariable power regression.Key Words: Culverts, broad-crested weirs, combined structures, discharge coefficient.