Abstract: The slurry produced by sand-washing engineering of excavated soil has the problems of poor dewatering property and instability, which are closely related to the dewatering performance of slurry. In this study, sand-washing slurry samples with different dewatering performances were obtained by simulating the field sand-washing process, then the modified filtration loss test and simulated pressure filtration test were carried out to study the influence of sand-washing process on the dewatering performance of sand-washing slurries, so as to find an index for rapid characterization of the dewatering performance of slurries, which can be used to guide the optimization of the sand-washing process. The results show that the dewatering performance of sand-washing slurry was significantly affected by the mesh size and the amount of water added. The filtration loss and hydraulic conductivity indicated a good correlation with the dewatering performance. In particular, the filtration loss at 30 minutes was nicely correlated with the final filtration loss and the final water content of filter cake, which can accurately reflect the dewatering performance. The results of simulated pressure filtration test further verify that the filtration loss at 30 minutes can be used as an index to quickly characterize the dewatering performance of slurries. Based on the above results, a method is put forward for rapid detection of sand-washing slurry dewatering and optimization of field sand-washing process. The method can provide guidance for the adjustment of sand-washing process parameters in time to obtain the sand-washing slurry with better dewatering performance, which can effectively improve and stabilize the dewatering effect.

Key words: sand-washing slurry, filter test, filter cake, filtration loss, dewatering performance