Degradation of straw-based wick drain and its effect on consolidation

Abstract

The recycling of straw, a type of agricultural waste in a large volume, has considerable attention, and attempts have been made to fabricate straw-based wick drains in soft clay ground improvement. Although it has low carbon emissions and is environmentally friendly, the biodegradation process of wick drains and its effect on consolidation need to be further investigated. In this study, the biodegradation process was examined by subjecting straw and plastic wick drains to degradation tests in soils from the prototypical project for comparison. The results show that the degradation of straw wick drains exhibits a decrease in the discharge capacity and tensile strength, and the degradation percentage of both exceeds by 30% after 240 days, whereas the mass loss is only 10%. After degradation, the abundance of cellulose-degrading bacteria increases by 3–10%, respectively. The biodegradable behavior of straw wick drains is achieved by the rapid community succession of multiple degrading bacteria and the population growth of cellulose-degrading bacteria. Afterwards, the theoretical calculation model considering the drain degradation was performed to understand the consolidation procedure, suggesting the effective substitution of straw wick drains.