冲刷作用下水平承载单桩静动力特性试验研究

Experiment on Lateral Behavior and Dynamic Characteristics of Single Piles Under Scour

为了掌握冲刷前后桩基水平承载性能的变化规律，并完成对冲刷前后单桩动力特性变化规律的探究，通过设计加工的水平加载装置，进行了一系列砂土中单桩室内模型试验，分析了不同冲刷深度下单桩水平极限承载力、沿桩身弯矩及单桩模态频率的变化规律．结果表明，在砂土地基中，当冲刷深度小于1．5倍桩径时，水平极限承载力受冲刷影响较小，而冲刷深度在2～8倍桩径范围时，水平极限承载力受冲刷影响较大，下降幅值达到80％，随着冲刷深度继续增大，水平极限承载力下降趋于平缓；另外，沿桩身的最大弯矩会随着冲刷深度的增加而减小，且最大弯矩点位置会随着冲刷深度的增加而上移，弯矩的主要影响范围在距砂土表面下5～8倍桩径处．单桩各阶模态频率随冲刷深度增加而降低，相同冲刷深度下随冲刷范围增大而减小．

The author devised laboratory model experiments under different scour depths, put forward some conclusions that were beneficial to practical engineering. When the scour depth was less than 1. 5 times pile diameter, the lateral load capacity was not likely to be influenced by scour, while the scour depth increased up to 8 times pile diameter, the lateral load capacity decreased 80% compared to un-scoured conditions. The bending moment along the pile decreased with the increase of scour depth, and the maximum bending moment occurred on the 5 times to 8 times pile diameter away from the sand interface. Moreover, the relationship between the scouring depth and natural vibration frequency was established, the tests showed that natural frequencies of the single pile reduce with the scour depth increasing.