水平瞬态荷载作用下桩土动力相互作用研究

Study of Pile-soil Dynamic Interaction under Horizontal Transient Loads

为研究桩基在桩-土界面连续条件下,桩顶受撞击等水平瞬态荷载作用时桩基位移响应、桩-土界面动力响应和桩周土的应力分布规律,根据Biot理论和Novak平面应变假定,采用Euler梁建立桩-饱和土耦合振动的平面应变简化模型,利用Laplace变换和势函数分解求解系统动力控制方程.针对桩-土系统在水平三角形冲击荷载作用下的振动状态,着重对桩基位移响应、桩-土界面和桩周土的动力响应开展时域分析.研究发现:桩-土系统的位移场响应滞后于应力场响应;桩土模量比越小,桩-土界面有效径向应力、切应力及孔压响应越显著;土体渗透系数减小引起桩-土界面孔压增大,导致有效径向应力减小,桩-土界面处切应力几乎不受渗透系数变化的影响;渗透系数较大时,桩周土孔压分布较分散,最大有效径向应力出现在桩-土界面附近;渗透系数较小时,桩周土孔压分布较为集中,最大有效径向应力则出现在桩-土界面较远处.

To study the displacement response of pile foundations,the dynamic response of pile-soil interface,and the law of stress distribution in the soil around the pile when the top of the pile is subjected to horizontal transient loads,such as impact,under the condition of continuity of the pile-soil interface,the simplified model of pile-saturated soil coupling vibration is established using the Euler beam based on the Biot theory and Novak plane strain assumption.The system’s dynamic control equations are solved using Laplace transformation and potential function decomposition.The focus is on the time-domain analysis of the vibration response of the pile-soil system under horizontal triangular impact loading,including pile displacement response,pile-soil interface,and dynamic response of the soil around the pile.The research reveals that the displacement field response of the pile-soil system lags behind the stress field response.Moreover,as the pile-soil modulus ratio decreases,the effective radial stress,shear stress,and pore pressure responses at the pile-soil interface become more pronounced.A decrease in soil permeability coefficient leads to increasing pore pressure at the pile-soil interface,causing a reduction of effective radial stress.The shear stress at the pile-soil interface remains almost unchanged with varying permeability coefficients.For higher permeability coefficients,the pore pressure distribution around the pile is more dispersed,and the maximum effective radial stress occurs near the pile-soil interface.Conversely,for lower permeability coefficients,the pore pressure distribution around the pile is more concentrated,and the maximum effective radial stress occurs at a greater distance from the pile-soil interface.