土体率效应对动力锚沉贯深度影响

动力安装锚(简称动力锚)是一种依靠自重进行安装、适用于深海锚泊系统的新型锚固基础.在动力沉贯过程中,土体经受很高的剪应变率(约25s-1),因此必须考虑土体率效应影响.总结了以往关于土体率效应的研究成果,整理了常用3种率效应模型中参数的取值范围,采用运动微分方程研究了不同率效应模型参数对动力锚沉贯深度的影响.结果表明:土体率效应会造成动力锚的沉贯深度显著减小,可偏小30%~40%;当率效应参数较大时,锚的沉贯深度对参考应变率的变化比较敏感;摩擦项与端承项的率效应比值对动力锚的沉贯深度影响较大,需要进一步研究该比值的确切取值方法;给出了可以满足任意形状和深度的矩形基础承载力计算公式.

Influence of soil strain-rate effect on embedment depth of dynamically installed anchors

Dynamically installed anchors, which are installed through self-weight, are newly developed anchors applied to deep-water mooring systems. During the dynamical embedment procedure, the soil is subjected to high shear strain-rate (about 25 s -1 ). Hence, the soil strain-rate effect should be necessarily taken into consideration. The ranges of soil strain-rate parameters of three commonly used models are summarized based on the published literatures referred to soil strain-rate effect, and the influence of strain-rate effect on the embedment depth of dynamically installed anchors based on the motion differential equation is discussed in the following. The research results indicate that the embedment depth of dynamically installed anchors would drastically decrease (30%-40%) due to the soil strain-rate effect. The embedment depth is sensitive to the reference strain-rate when strain-rate parameters are in high values. The shear strain-rate effect ratio of the frictional resistance to the end bearing resistance has significant effect on the embedment depth and further investigation is necessitated to define this ratio. A new formula is proposed to calculate the bearing capacity of rectangular footing with any shape and embedment depth.