Scour mitigation and erodibility improvement using microbially induced carbonate precipitation

Abstract

Enhancing the scour resistance of foundation systems supporting superstructures over waterways is required for the sustainable functionality of the structure. In this article, the use of microbially induced carbonate precipitation (MICP) was investigated for the potential of its use in scour mitigation and erodibility improvement of sand. Testing was performed in a 0.91 by 1.22 by 1.22-m model box, and a double wall delivery system was developed and used to target cementation near the surface. A comparative study was performed on the scour behavior of untreated and treated samples using data from a series of flow tests. Impinging jet testing was used to evaluate the erodibility parameters of treated sand. The results from flow testing indicated that untreated and lightly cemented zones showed similar scour depth, whereas indiscernible scour was observed for the heavily cemented zone. The improvement distribution pattern throughout the media showed an ellipsoidal shape with respect to the injection source. The scour behavior and the cementation pattern indicated less cementation was achieved at the zone near the injection source because of high induced seepage velocity. Based on the impinging jet testing results, an empirical erosion model for MICP-treated sand is proposed as a function of the level of cementation.