Bio-Inspired Bridge Scour Countermeasures: Streamlining and Biocementation

Abstract

Bridge scour has long been identified as the major cause to bridge failures. This paper presents the results of an experimental study on the effectiveness of two newly-proposed scour countermeasures, namely streamlining and biocementation, which are inspired by nature. On one hand, borrowing ideas from the streamlined body shape of boxfish and blue shark, this study introduces streamlining features to bridge piers in order to reduce the flow intensities in the vicinity of bridge piers. Based on the numerical results of a pier streamlining optimization study previously conducted, four small-scale pier models with different streamlining levels were constructed using 3D printing techniques and flume tests were conducted to characterize the scour process around these models. On the other hand, microbial induced carbonate precipitation (MICP) is an emerging technique in geotechnical engineering. It precipitates carbonate that binds soil particles together and thus improves soil properties. In this study, a standard soil, Ottawa graded sand, was treated with bacteria (Sporosarcina pasteurii) in a full-contact reactor where the soil in a fabric mold was fully immersed in bacteria and cementation solution. The treated sample was tested in a flume to investigate the effectiveness of MICP on bridge scour control. The experimental results reveal that both streamlining and biocementation can significantly reduce or even fully prevent the scour around the model bridge piers under the laboratory testing conditions.