Cause of abnormal local settlement of section S5+000～S6+700 of southern training bank in the Yangtze Estuary and restoration design

Through field investigation and fluvial regime analysis,it is discovered that the local settlement of section S5+000～S6+700 of the southern training bank in the Yangtze Estuary was caused by the washing-away of the sand on the foundation bed through some joints between the bed protection mattresses where there was a lack of overlapping during the long-termaction of the driving currents along the bank formed by the blockage of current motion in Jiangya North Passage.Thus,the measure of enhancing the safety guarantee of the bed protection mattress structure was taken in the restoration design,through which a satisfactory effect was achieved.