复合加载模式下不排水饱和软黏土中宽浅式筒型基础地基承载力包络线研究

Failure envelopes of large-diameter shallow buried bucket foundation in undrained saturated soft clay under combined loading conditions

作为高耸结构物,海上风机受到巨大的水平荷载作用。宽浅式筒型基础是为适应中国近海荷载特点而研发的一种新型海上风机基础形式,经典的地基承载力计算公式无法精确地计算复合加载模式下宽浅式筒型基础地基的极限承载力。通过数值计算研究了不排水饱和软黏土中宽浅式筒型基础在V-H、V-M、H-M和V-H-M加载模式下的地基承载力包络线,并提出了V-H和V-M加载模式下的地基承载力包络线的表达式。研究结果表明V-H和V-M加载模式下宽浅式筒型基础地基承载力包络线具有对称性,而H-M加载模式下呈非对称性,其非对称性随着基础深宽比增大而更加显著;V-H-M加载模式下地基承载力包络线的形状受竖向荷载V的影响,表现为包络线关于M轴的非对称性随着竖向荷载的增大而减弱。可根据海上风机的实际受力状态与该破坏包络线之间的相对关系,评价实际受荷状态下筒型基础的稳定性。

As a towering building, the offshore wind turbine is often subjected to significant horizontal load. The large-diameter shallow bucket foundation is a new kind of foundation to adapt to the special load conditions of offshore in China. The classical approach for the bearing capacity is not able to evaluate the bearing capacity of large-diameter bucket foundation. The failure envelopes of large-diameter bucket foundation on soft soil ground without drainage conditions in V-H, V-M, H-M and V-H-M loading spaces are investigated by means of the finite element method. Some formulas are obtained to describe the failure envelopes in V-H and V-M loading spaces. It is shown that the failure envelopes in V-H and V-M spaces are symmetric, while the failure envelope in H-M space becomes more asymmetric with the increasing depth ratio. The vertical load V affects the shape of the failure envelope in V-H-M loading space. The asymmetry of the failure envelope around M-axial recedes with the increasing vertical load. According to the relationship between the actual combined loading and the computed failure envelopes, the stability of large-diameter shallow bucket foundation can be determined.