冲刷对桩井基础水平承载特性影响的试验研究

Model Tests on the Influence of Scour on Lateral Response of Deep Foundations

大直径单桩基础及沉井加桩复合基础是近海工程中重要的深基础形式,其受力情况较为复杂,不仅受多种荷载的耦合作用,往往还受到波流的冲刷作用。目前关于冲刷的研究多集中于研究水流与土体的相互作用,即冲刷坑的形成机理,而有关冲刷坑的形成对基础承载力影响的研究则较少。通过室内模型试验,采用开挖对冲刷效应进行模拟,研究单桩及沉井加桩基础在冲刷前后水平承载性能的变化。试验结果表明,冲刷会显著降低上述两类基础的水平极限承载力;水平荷载达到极限承载力时,基础的弯矩幅值及基础周围土抗力幅值在冲刷后有明显下降。

Large-diameter pile and composite caisson-piles foundation are significant forms of deep foundation in offshore engineering which are under complex force condition. Besides taking coupling loads,they often serve under the effect of scour due to wave-current. By now,most of the study on scour focus on the interaction between wavecurrent and soil mass,or the formation mechanism of scour pits,while there are few about the effect of scour on the lateral capacity of foundation. Indoor model tests were conducted to analyze the changes of lateral bearing behavior before and after scour where the scour effect was simulated by excavation. The results showed that the scour impaired the lateral capacity of both large-diameter pile foundation and open caisson significantly. When the lateral load reached the lateral capacity,the maximum value of foundation bending moment and the earth pressure around it had obvious decrease compared with that before scour.