Study of design parameters for staged-filled slurry treated by prefabricated horizontal drains under vacuum preloading

• Published in: Geotextiles and geomembranes Vol. 52; no. 5; pp. 985 - 998
• Main Authors: Song, Ding-Bao, Pan, Yu, Chen, Wen-Bo, Wu, Pei-Chen, Yin, Jian-Hua
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Field test; Numerical simulation; Prefabricated horizontal drain; Staged-filled slurry; Vacuum consolidation; Vacuum consolidation; Staged-filled slurry; Numerical simulation; Field test; Prefabricated horizontal drain
• ISSN: 0266-1144; 1879-3584
• DOI: 10.1016/j.geotexmem.2024.05.011

The method of using Prefabricated Horizontal Drains (PHDs) placed in layers under vacuum preloading can significantly speed up consolidation of staged-filled soil slurry. The PHDs can settle with the soil slurry and maintain their shape/pattern and dewatering capacity largely in comparison with Prefabricated Vertical Drains (PVDs). This study presents a field trial focused on treating dredged sediments using PHDs under vacuum preloading for land reclamation purposes. The staged filling involved in the field trial is analyzed using a finite strain consolidation model based on the piecewise-linear finite-difference method. Then, the effects of horizontal and vertical spacings of PHDs on settlement and vacuum consolidation rate are evaluated, considering various combinations of variables for staged-filled soil. It is found that for soils with low compressibility, the consolidation rate is primarily affected by the vertical spacing of PHD layers. For soils with higher compressibility, the consolidation rate is more significantly affected by the horizontal spacing of PHDs, and the final settlement after vacuum preloading is mainly influenced by the vertical spacing of PHD layers. This study provides practical recommendations for cost-effective design of horizontal and vertical spacings of PHDs in efficiently treating soil slurry with different compressibility and initial conditions. •A consolidation numerical model was developed for staged-filled soil mud with or without prefabricated horizontal drains.•Field trial conducted in Hong Kong involving vacuum consolidation of soil mud with PHDs was presented.•For soil with high compressibility, the vertical spacing of PHD layers has a pronounced impact on the final settlement.•Consolidation rate of soil with low compressibility is largely affected by the vertical spacing of PHD layers.