基于Winkler地基理论的横向受荷长桩非线性动力响应模型试验

Model tests of nonlinear dynamic responses for laterally loaded long piles based on Winkler foundation theory

基于Winkler模型,将弹性地基离散化为线性弹簧,建立长桩-弹簧动力相互作用模型试验系统,研究了桩顶横向简谐激励下桩基的非线性动力响应。通过两组共12种工况模型试验,分析了桩身参数、地基约束、桩顶配重和激励特征等对桩基动力响应幅值、共振和空间运动的影响。试验结果表明:随激励幅值增大,桩基动力响应的非线性特征显著;在特定的激励频率下,激振器与模型桩发生共振,在一定程度上改变桩-土系统的动力响应特征;若放松地基约束,桩基主共振响应呈软弹簧特性,表明土-结构相互作用对桩基的动力学特性有定性影响;改变桩顶配重,在小幅激励下桩基响应幅值的变化较大;由动力轨迹可知,桩顶有明显的面外运动。研究建立了理论分析与试验测试的直接关联,促进了基于Winkler模型开展的横向受荷长桩非线性动力学试验研究。

Based on Winkler model,an elastic foundation was discretized as linear springs to establish a long pile-spring dynamic interaction model test system,and study nonlinear dynamic responses of pile foundation under a lateral simple harmonic excitation exerted on pile top.Through model tests under 12 working conditions in two groups,influences of pile parameters,foundation constraints,pile top counterweight and excitation characteristics on dynamic response amplitude,resonance and spatial motion of pile foundation were analyzed.The test results showed that nonlinear characteristics of pile foundation dynamic response are significant with increase in excitation amplitude;under a specific excitation frequency,the vibration exciter resonates with the model pile to change dynamic response characteristics of the pile-soil system to a certain extent;if foundation constraints are relaxed,the main resonance response of pile foundation is characterized by soft spring,so soil-structure interaction has a qualitative influence on dynamic characteristics of pile foundation;with the change of pile top counterweight,the response amplitude of pile foundation changes greatly under small amplitude excitation;observing the pile top’s dynamic trajectory,it has an obvious out of plane motion;here,the direct correlation between theoretical analysis and tests is established to promote nonlinear dynamic tests of laterally loaded long piles based on Winkler model.