Laboratory Scour Testing of Hard Cohesive Soils in Alabama

Abstract

Establishing scour parameters in order to estimate the loss of soil adjacent to bridge piers is a crucial element in the design of highway bridges crossing over rivers and streams. Although there are numerous design criteria for estimating scour in cohesionless soils, methods for calculating scour in cohesive soil are limited. By conducting scour tests using an Erosion Function Apparatus (EFA), erosion functions were established for six different soil formations found throughout southern Alabama. The erosion functions were modified to incorporate the effects of sample swell during testing. Correlations between scourability and conventional geotechnical parameters were established using the results of the EFA tests. These correlations were compared to trends seen in previous studies at Auburn University. The scourability of these clay formations were observed to be dependent upon the Standard Penetration Test N value, insitu moisture content, and percentage of soil passing the number 200 sieve.