Experimental studies of the flow-front and drag forces
exerted by subaqueous mudflow on inclined base
Zainul Faizien Haza • Indra Sati Hamonangan Harahap •
Lema Mosissa Dakssa
Abstract Submarine slides are one of the most complex geotechnical problems causing
serious damages to the seabed environment. Damages may lead to imminent destruction of
offshore facilities such as platform and subsea pipeline. Mud sediment was the most
susceptible of subsea material involved in the event. The completeness of field investigation
is very limited; therefore, laboratory experiment is implemented in view of modeling
the dynamics movement at the time of submarine slides occurs. The current
experiment was conducted by generating the mudflow in water ambient over an inclined
base to observe the flow-front structures of the mudflow. As facility to investigate the drag
force exerted by mudflow, additional pipe model was positioned at certain flow distance.
Mud models were prepared from mixtures of 10–35 % by weight of kaolin and water.
Mudflow observations were limited to 3.5-m run-out distance with an exemption for 35 %
KCC since this percentage stopped flow at 2.3-m flow distance. The role analysis of
destructive flow was developed by the determination of drag force coefficient exerted by
mudflow incorporating the Reynolds number. Velocity analysis indicates that all flows
were defined as initial flow since they have only one phase of slumping phase. With respect
to head-flow height and densimetric Froude number, the general form of velocity propagation
formula provided the satisfactorily results in tracing mudflow velocity observation
of laboratory experiment. Furthermore, the higher percentage of KCC exerted the higher
drag force than the lower one.
Keywords Submarine slide . Mudflow . Kaolin clay . Head-flow height .
Drag force . Drag force coefficient