砂土中冲刷条件下三筒基础水平承载特性研究

Characteristics of horizontal bearing in tripod-bucket foundation subjected to scouring in sand

通过开展小比尺三筒基础承载力模型试验,研究冲刷条件下三筒基础水平承载特性,建立数值模型对模型试验结果进行验证与扩展,分析水平和弯矩荷载下,冲刷率e和相对筒间距S/D对极限承载力的影响,提出三筒基础极限承载力的冲刷修正系数dhe、dme的计算方法;采用固定荷载比方法,通过数值模型计算M-H加载条件下三筒基础的破坏包络线,分析冲刷率e和相对筒间距S/D对复合加载特性的影响,提出冲刷条件下三筒基础M-H破坏包络线公式。研究结果表明:冲刷条件下的三筒基础受水平和弯矩作用直至破坏的过程,经历弹性变形—塑性变形—失稳破坏3个阶段;三筒基础的水平极限承载力随冲刷率e的增大而下降,且下降速率逐渐增大,相同长径比的三筒基础的水平极限承载力随相对筒间距的减小而降低;随着冲刷率e的提高,三筒基础的M-H破坏包络线向内移动,随着相对筒间距S/D增大,归一化破坏包络线呈上凸的趋势。

This study presents the findings of small-scale model tests conducted to investigate the horizontal bearing characteristics of tripod-bucket foundations subjected to scouring conditions in sand.The experimental results served as the basis for analyzing the effects of scour rate e and bucket spacing S/D on the horizontal and bending moment bearing capacity through numerical simulations.Additionally,a calculation method for scour correction coefficients dhe and dme of the ultimate bearing capacity was proposed.By employing the fixed load ratio method,the failure envelope of the tripod-bucket foundation under combined horizontal and bending moment M-H loads was determined.The impact of scour rate e and bucket spacing S/D on the failure envelope was thoroughly examined,leading to the development of a formula for the M-H failure envelope of the tripod-bucket foundation under scouring conditions.The results indicate that the failure process of the tripod-bucket foundation under scouring conditions can be categorized into three stages:elastic deformation,plastic deformation,and instability failure.The horizontal ultimate bearing capacity of a three-cylinder foundation decreases with the increasing erosion rate e,and the rate of decrease progressively accelerates,while for three-cylinder foundations with the same length-to-diameter ratio,the horizontal ultimate bearing capacity decreases with a reduction in the relative spacing between the cylinders.With the increase in erosion rate e,the M-H failure envelope of the three-cylinder foundation shifts inward,and as the relative spacing between the cylinders S/D increases,the normalized failure envelope tends to exhibit an upward convex trend.