Filtration characteristics of coconut fiber filter used in emergency rescue of dike piping

After the occurrence of backward erosion piping (BEP) in dikes, timely emergency rescue is crucial. Based on the coconut fiber filter, a quick and eco-friendly method for protecting against dike BEP is proposed. To investigate the filtration characteristics of coconut fiber filters during BEP rescue, model experiments were conducted. The impact of filter pore size on its filtration performance was explored. The distribution of clogging particles within the filter was observed using an electron microscope, and the filtration mechanism of the coconut fiber filter was revealed. The results show that in continuous graded sand, there was no significant clogging of the coconut fiber filter. By the end of the experiment, the flow rate of the 300 g/m² coconut fiber filter was 52.4% higher than that of nonwoven geotextiles. Compared to nonwoven geotextiles, the coconut fiber filter exhibited better filtration performance. When the pore size of the coconut fiber filter exceeded a certain threshold, the clogging degree in the filter increased rather than decreased. Physical clogging of the nonwoven geotextile system mainly occurred near the filter, while for the coconut fiber filter system, it mainly appeared within the sand layer 3–25 mm below the filter.