Surface and Internal Erosion Responses of Earthen Levee Structures Reinforced by Biopolymer-Based Soil Treatment (BPST) Assessed via Open-Channel Hydraulic Flume Apparatus

Abstract

The failure of earthen dams and levee structures are mostly caused by hydraulic erosion measures including overflow (surface) or piping (internal). Several research have attempted to control and mitigate surface and internal erosion of waterfront geotechnical engineering structures via seepage control and soil shear strength improvement. Meanwhile, microbial biopolymer-based soil treatment (BPST) is gaining attention as a new environmentally friendly method to amend the geotechnical engineering properties of soil in terms of: strength improvement, hydraulic conductivity reduction, erosion resistance enhancement, and surface vegetation growth. In this study, BPST has been attempted to improve the overall stability and erosion resistance of earthen levee structures, where severe overflow and internal piping conditions were simulated by a laboratory open-channel hydraulic flume apparatus. Small scale (50:1) levee models were prepared with different BPST (e.g., biopolymer contents) treatment conditions. Surface erosion has been simulated by allowing continuous overtopping, while internal erosion (piping) has been considered by initiating internal leakage through a pre-drilled hole along the bottom of the levee model. The erosion amount (volume and mass) with time has been monitored for all test conditions. The results show BPST having a significant effect on reducing both surface and internal erosion of an earthen levee structure with a small biopolymer quantity and treatment proportion compared to the entire volume of the levee model.