Experimental study on hole erosion behaviors of marine soil solidified by an innovative organic composite material

• An innovative composite solidifier, known as organic composite materials (OCM), was developed firstly and used to treat marine soil. • The effects of marine temperature, solidifier content, and curing time on the internal erosion behavior of marine solidified soil were investigated in detail. • The inner mechanism of organic composite materials solidified soil to resist erosion was clarified. To enhance the erosion resistance of marine soil and ensure the stability of offshore infrastructures, this study developed an innovative organic composite material (OCM) as a solidifier. The erosion resistance of OCM-treated marine soil was evaluated using a hole erosion test apparatus, capturing the complete erosion process, including temperature regulation, water storage hole cleaning, linear erosion, and accelerated erosion stages. A relationship between hydraulic shear stress and erosion rate was established, focusing on two key parameters: critical shear stress τ c and erosion rate index ERI. Results demonstrated that OCM significantly improved erosion resistance by maintaining soil structural integrity under scour conditions. This enhancement was attributed to the filling and bonding effects of hydration products such as calcium silicate hydrate (C-S-H), ettringite (AFt), and calcium hydroxide. Increasing solidifier content and extending curing time further enhanced the erosion resistance of soil, but the increase in OPC group was significantly less than that in OCM group. Specifically, when the solidifier content increase from 5 % to 10 %, the τ c and ERI of OPC samples at 4 h curing time increased by 87 % and 15.9 %, while the τ c and ERI of OCM samples at 4 h curing time increased by 86 % and 24.5 %. Additionally, as the temperature increased, the double electrical layer force between the solidified soil structures weakened, thus decreasing the critical shear stress of soil. These findings highlight the superior performance of OCM in enhancing marine soil stability, making it a promising solution for long-term offshore infrastructure protection against erosion.