Strengthening Coastal Sand Dunes Using Microbial-Induced Calcite Precipitation

Abstract

In the event of large storms, coastal regions are particularly vulnerable. The effect of erosion on coastal soils can be devastating, and may result in damage to structures, roadways, and utilities. This damage can be extremely costly and may result in serious harm. Previous work has shown that the strength and stiffness of loose, saturated sand increases by utilizing microbial induced carbonate precipitation (MICP). The work presented herein applies the MICP treatment process to sandy coastal soil in order to increase its resistance to erosion. Utilizing the MICP treatment technique in unsaturated soils, rigid-wall soil column tests were conducted. The soil tested was clean fine sand, typical of coastal dune deposits. The soil remained unsaturated by allowing free drainage during treatments. Shear strength was measured through unconfined compression testing. By upscaling the treatment process, a bench model simulating a costal sand dune was tested to determine the change in the angle of repose for the MICP treated soil and its increase in erosion resistance. Erosion due to wave action was assessed by comparing the behavior of an untreated model sand dune to a MICP treated model sand dune subjected to simulated waves.