Large trailing suction hopper dredgers may experience pronounced layer-thickness fluctuations and discontinuous strip coverage when conducting backfilling over deep soft-soil foundations.To address this engineering problem,a quality database for layered sailing side-casting backfilling is established based on high-precision RTK-GNSS vessel tracks and multi-period multibeam bathymetric surveys from the Pasay backfilling project in the Philippines.Statistical indicators,including mean thickness,unit-area thickness,thickness coefficient of variation,and effective coverage width,are employed to systematically investigate the coupled effects of bottom-door opening,sailing speed,and flushing-water flow rate on backfilling thickness and uniformity,and to summarize adaptive rules for on-site parameter adjustment.The results show that within a practical control window with a bottom-door opening of 30% to 50%,a sailing speed of 1.2-1.8 kn,and a flushing water flow rate of approximately 2,000 m3/h,the single-layer thickness can be maintained at 0.45-0.60 m,the measured total thickness ranges from 1.88 to 2.14 m,the thickness coefficient of variation is generally below 0.12,and the final construction surface elevation deviation is controlled within ±0.15 m of the design value.This study clarifies the quantitative relationships between key operational parameters and backfilling thickness-control indicators,and proposes an optimized parameter window and an on-site control method for layered moving discharge backfilling by trailing suction hopper dredger over deep soft-soil foundations,providing technical support for process selection and construction quality assessment in similar projects.