Application of improved multilayer extraction sampling to change of shear strength of dredged material during deposition process

The existing multilayer extraction sampling cannot test shear strength of dredged material during deposition process, and the cost is high because it needs a pore water pressure sensor at each selected pressure tapping. So the multilayer extraction sampling is improved, mainly including a laboratory miniature high-precision shear vane apparatus and an apparatus that one pressure sensor connects successively automatically to each pressure tapping at different heights of sediment column. The experimental results show that the measured data are reasonable and the improved test method is feasible. The improved multilayer extraction sampling can test the level of the mud-water interface, water content (density), excess pore water pressure, effective stress, grain size distribution, undrained shear strength, compressibility, and permeability, ect. Self-weight consolidation and shear strength of the dredged material during deposition process can be studied. The experimental results can be used for numerical simulation of large strain self-weight consolidation.