Zhang, S.; Zhao, M.; Ge, T., and Wang, C., 2016. Experimental research on trenching in stiff clay by submerged vertical traveling jets.

This study investigated trenching by submerged circular traveling jets in stiff clay using an experimental method. The testing clay was prepared as mixtures of natural clay and cement with shear strength ranging from 60 kPa to 90 kPa. The jet pressure, the nozzle translational velocity, and the diameter of the nozzle all varied in the test. A cohesive sediment scouring theory was employed to reveal the mechanism of the jet trenching. It showed that the boundary layer shear force on the jet-soil interface might be the predominant mobilizing force for jet trenching. The trench depth was found to increase with the jet pressure, erodibility coefficient, and the diameter of the nozzle and decrease with the translational velocity of the nozzle and the threshold stress of the clay. The essence of the traveling jet trenching could be considered as jet erosion. The efficiency of jet trenching was found be higher when the jet worked with low pressure and large diameter. The trench depth of a large nozzle could be obtained by testing a small one.