🇧🇷 PROJETO: ESCORREGAMENTO SUBMARINO I SUBMARINE DEBRIS FLOW I CENTRÍFUGA GEOTÉCNICA DA UENF CAMPOS
PROJETO PETROBRAS
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The occurrence of landslides on the seabed is a common phenomenon in many different ocean environments. These events have become one of the principal threats to the integrity of seabed structures, with pipelines being most exposed to the risk of impact, causing economic, environmental and social damage. Geotechnical centrifuge tests were conducted in order to evaluate the mechanisms of submarine debris landslides on pipelines installed on the seabed as a function of its embedment ratio.
The model comprises a very gentle ramp instrumented with pore pressure transducers and total stress cells strategically placed in the mud runway in order to capture the mudslide features and hydroplaning. At the end of the ramp, a pipe was instrumented with strain gauges and accelerometers in order to record the deformations and estimating the forces. The high-speed camera was attached to the model to allow synchronization amongst all instruments readings as the test progresses and for the image analysis, as well as for image analysis and sliding velocity calculation. Analysis was performed to correlate the dimensionless parameters with the exposure rate of the pipeline, which ranged from 100% to 25%. The tests showed that the drag coefficient is directly influenced by the exposed diameter of the pipeline.
The UENF Geotechnical Centrifuge is a Physical Modeling Equipment in Geotechnics, installed on the UENF Campus, capable of testing models of up to one ton in an environment whose gravitational pressure can reach up to one hundred times the Earth's gravity.
The UENF Geotechnical Centrifuge has, in operation, about seven meters in diameter and two baskets, which house the containers (models), allowing two simultaneous tests. The purpose of Centrifugation is to subject a reduced scale physical model to a modified gravitational field in order to reproduce the state of tension under which the prototype is subjected in inverse relation to the scale used. During the flight, the centripetal force arising from the acceleration of the centrifuge imposed on the model, generated in the circular motion, is equivalent to the modified gravitational force. The main advantage of using the Centrifuge is the possibility of reconstructing the stresses arising from the gravitational forces under which the prototype will be subjected and the flexibility in modeling extreme cases or phenomena still little known. With this, using the similarity laws, it is possible to reproduce the behavior of the structure or the phenomenon studied in reduced models as if they were in the real dimension of the prototype."