Multiflood and Multilayer Method for Scour Rate Prediction at Bridge Piers

The SRICOS method was proposed in 1999 to predict the scour depth versus time curve at a cylindrical bridge pier for a constant velocity flow, a uniform soil, and a deep-water condition. In this article, the method is extended to include a random velocity-time history and a multilayer soil stratigraphy; it is called the Extended-SRICOS or E-SRICOS. The algorithms to accumulate the effects of different velocities and to sequence through a series of soil layers are described. The procedure followed by the computer program to step into time is outlined. A simplified version of E-SRICOS called S-SRICOS is also presented; calculations for the S-SRICOS method can easily be done by hand. Eight bridges in Texas are used as case histories to compare predictions by the two new methods (E-SRICOS and S-SRICOS) with measurements at the bridge sites.