Improved subgrade reaction model in designing embedded piles exposed to static lateral head loads

摘要

Based upon the results of recent model tests with vertical piles exposed to lateral head loads, some new findings upon soil-pile head interaction are reported here. The bearing behavior of piles carrying off lateral loads at the pile head towards the surrounding soil is determined by the development of horizontal reaction stresses, as in prototype scale for instance at bridge abutments, in offshore piling (cyclic loading with low frequency due to wave excitation) or cantilevers of noise load reduction walls as to highspeed railway tracks (dynamic loading due to higher frequencies of wind shockwaves). In daily design practice the pile-soil-interaction is commonly disregarded or represented in extremely simplified forms, like linear subgrade reaction models with stepwise control of the equilibrium between reaction stresses and passive earth pressure to be mobilized. This usually leads to an uneconomic - but safe sided - design, because a strong restraining effect at the toe of the pile is disregarded. The main focus in this contribution is a simple approach to assess the development and redistribution of reaction stresses along the pile-axis due to the imposed head displacement of the pile in static monotonic loading.