室内静压沉桩试验桩周土体全过程位移场分析

Analyses on Soil Displacement Field Caused by Pressin Process of Pile Model Tests

摘要:

采用室内半桩模型试验研究了砂土中静压桩沉桩过程，基于DIC(digital image correlation)技术对桩周土体位移发展与相应土压力变化律进行了分析研究.试验采用无标识点方法对桩周土体累计竖向位移发展规律进行了全过程分析，并拟合出了桩周土体位移轨迹，揭示了桩周不同位置土体的运动规律.通过对桩周土体竖向位移与相应位置土压力变化进行联合分析，从土体变形的角度对土压力变化机理进行了解释与证明，实现了力与位移关系的统一.最后对沉桩速度对桩周土体位移的影响进行研究.研究成果对于进一步明确沉桩挤土效应内在机理和桩周土体压力的发展规律提供参考.

关键词:静压桩; DIC(digital image correlation)技术; 沉桩过程; 挤土位移场; 土压力变化机理

Abstract:

Base on the digital image correlation (DIC) technique, soil displacements and corresponding earth pressures induced by pressin process of pile model tests were studied. In the model tests, the vertical accumulative soil displacements were tracked without marks. The soil displacement trajectories were plotted, which revelated that pile pressin process caused different soil displacement paths at different depths and locations. Through joint analysis on the vertical displacements of soils around the pile and the corresponding earth pressure, the mechanism of earth pressure change was explained from the perspective of soil deformation. It shows that the displacement and earth pressure induced by advance of pile were conjugative. Finally, the influence of pressin velocity on soil displacements was investigated. The analyses presented in this study tended to further clarify the squeezing effect caused by pile pressin process and the mechanism of the development of earth pressures around the pile.

Key words:jacked pile; digital image correlation(DIC) technology; punching process; compacting displacement field; mechanism of soil pressure changes