砂土中螺旋锚基础水平振动特性的模型试验研究

在水平激励作用下,钢管螺旋锚基础-土的动力相互作用具有明显的非线性特性。基于自制的锚土动力相互作用模型试验系统,对砂土中不同锚体几何结构的钢管螺旋锚的水平振动响应特性进行了研究,具体分析了螺旋锚长径比(L/D)、叶片距宽比(S/D0)、叶片外伸比(D0/D)、不同荷载幅值(F0)和振动频率(f)等对螺旋锚水平动力响应特性的影响,并与直桩进行了对比分析。通过研究螺旋锚周围土体的应力扩散,讨论了水平动力荷载作用下螺旋锚-土的相互作用规律。研究结果表明:长径比(L/D)是影响直桩和螺旋锚水平动力响应特性的重要因素;在锚径相同的条件下,锚土系统的共振频率随锚体长径比的增加而减小,随叶片外伸比的增加而增加,但对叶片距宽比相对不敏感;在锚体几何结构相同的前提下,激振荷载幅值越大,直桩土系统的共振频率越小,但激振荷载幅值对螺旋锚土系统共振频率的影响相对较小。

Experimental study on vibration response characteristics of screw pile foundation in sand under lateral dynamic loading

Under the lateral dynamic loading,the dynamic interaction between the steel screw pile and the soil shows the dramatic nonlinear effects.Based on the self-made model test system of pile-soil dynamic interaction,the horizontal vibration response characteristics of steel screw piles with different pile geometry in sand are experimentally studied.Effects of the blade spacing-width ratio(S/D0),the extended length ratio(D0/D),the loading amplitude(F0)and vibration frequency(f)on the horizontal dynamic response characteristics of screw piles are analyzed,which are compared with vertical piles.Moreover,by investigating the stress diffusion of soil around steel screw piles,the dynamic interaction rules between the screw pile and the soil under lateral dynamic loading are also discussed.Research results show that the length-diameter ratio(L/D)is an important indicator in affecting the horizontal dynamic response for the vertical and screw piles.The resonance frequency of the screw pile-soil system decreases with the increase of the length-diameter ratio for the same pile diameter,and increases with the increase of the blade extended length ratio.However,the resonance frequency of the screw pile is relativelyinsensitive to the blade spacing-width ratio.Under the same pile geometry,the higher loading amplitude will lead to the lower resonance frequency of vertical pile-soil system.But the loading amplitude has less influence on the resonance frequency of screw pile-soil system.These research results may provide guidance for the multi-functional design of horizontal vibration characteristics of screw pile foundations.