Abstract: Clogging areas often form around the prefabricated vertical drainage plates during the vacuum preloading of waste slurry. Accurate measurement and calculation of the permeability coefficient of mud in the clogging zone are critical for predicting the consolidation of waste slurry. Since the permeability coefficient of mud in the clogging zone is difficult to measure directly and there is a lack of theoretical derivation for it, a calculation method for the permeability coefficient and thickness of the clogging zone was proposed. A test device was established to investigate the formation of the clogging zone and validate the calculation method. The test proved the practicability and feasibility of the calculation method. It is concluded that when conducting vacuum preloading on waste slurry at construction sites, the vacuum degree should be controlled below 90 kPa, and the lower the vacuum degree used in the vacuum preloading between 60 kPa and 90 kPa, the slower the formation of the clogging zone is. The proposed permeability coefficient calculation method for the clogging zone can be used to predict the degree of mud consolidation during the vacuum preloading process.

Key words: waste slurry, vacuum preloading, clogging zone, permeability coefficient, calculation method