Stability of an underwater trench in marine clay under ocean wave impact

摘要

A long section of the immersed tunnel of the Busan-Geoje Fixed Link in South Korea is to beconstructed in a trench in soft marine clay. The site is exposed to large typhoon waves and the trench is to beleft open for approximately one year. The trench profile was chosen as a balance between excavated volume(costs) and risk of slope instability under large waves. To evaluate this risk, far-shore wave data have beentransformed into near-shore wave conditions by means of numerical modelling and wave flume tests have beencarried. Potentially critical waves have been identified and their impact has been analysed by means of coupledhydro-mechanical numerical simulations. Based on the strength reduction method, safety factors for the slopestability during wave impact have been determined. The results and the consequences for the economic designof such a trench subject to large waves are discussed.