Abstract: An ooze seam in a plain river network area generally has a large thickness and a low strength. In such an area, when some ports are built or expanded, the soft soil layers should be dug out and backfilled, leading to a high construction cost. Then the unloading-type sheet pile has be adopted to resolve the above issues owing to its lower construction expense. But the earth pressure for this structure has yet to be effectively evaluated. By drawing lessons from the earth pressure calculation of covered sheet pile wharf, a method for calculating earth pressure for this new structure is proposed. In this method, the whole structure is first divided into many parts, and then the earth pressures on sheet piles facing river and bored piles oriented to land are calculated based on the non-limit state earth pressure theory, meanwhile the earth pressures of sheet pile landside and bored pile riverside are also determined with considering the effect of soil arching and unloading. By comparing the analytical results with the results obtained from centrifuge model tests and finite element method, the applicability and reliability of the proposed method is demonstrated.

Key words: unloading-type sheet pile, earth pressure theory, finite element analysis, centrifugal model test