Comments on Conventional Design of Retaining Structures

Abstract

The performance of earth retaining structures is analyzed to illustrate certain weaknesses in the conventional design practice. It is shown that the yielding of a retaining structure by an amount required for the earth pressure to drop to the minimum active state does not necessarily provide assurance that active earth pressure will prevail for more than a limited period of time. If a design is based on the active earth pressure, while the actual earth pressure may at times be equal to or greater than the earth pressure at rest, the actual factor of safety would be close to unity. It is demonstrated that anchored bulkheads are particularly vulnerable in this respect because the design of a competent anchorage may require an assumption of forces at the anchor level that are equal to two to three times those computed on the basis of a conventional design using active earth pressure.