高频振动沉桩全过程数值模拟的方法与应用

Method and Application of Numerical Simulation for Full Process of Pile Driving by Using High Frequency Hammers

通过有限元软件ABAQUS建立高频液压振动打桩的三维模型,研究高频打桩对周围土层性质的影响。为了更好的贯入,在桩轴线处建立半径为1 mm的管。采用Coulomb的本构接触摩擦模型,管土的切向摩擦设为光滑,桩土接触采用罚函数,法向均采用硬接触。打入桩和圆管采用离散刚体壳模拟,土体采用摩尔库伦本构模型,很好的实现不排水条件下高频液压振动沉桩整个过程的数值分析。贯入模拟过程表明桩尖周围土体的水平应力和竖向应力发生应力突变现象;静载力越小,激振力越大,影响越大;频率越大,贯入时间越长;土体越坚硬,影响越大;桩土摩擦系数越大,影响越大。

Here ,the three-dimensional model of high-frequency hydraulic vibration pile driving is established by using fi -nite element software ABAQUS so as to study the the effects of the pile driving on the surrounding soils .A rigid tube with 1 .0 mm radius is modeled along the axis of the pile for better penetration .Based on constitutive contact law ,the Coulomb friction model is used throughout all analyses .There is a frictionless contact between the tube and soil on the tangential direction ,and the penalty function is used in pile-soil contact ,while the hard contact is used on the normal di-rection .Moreover ,the driven pile and tube are simulated with discrete rigid body ,and the soil is simulated with Mohr-Coulomb model .Then the numerical analysis for the full process of the pile driving under undrained condition is per -formed by using high frequency hydraulic hammers .The numerical simulation analysis of pile penetration process shows that there is a stress mutation occurred both in the horizontal stress and vertical stress of the soils around pile toe .The in-crease of the effect on soils is greater with the decrease of static forces and the increase of exciting forces .The larger the frequency is ,the longer time the penetration uses .Moreover ,the harder the soil is ,the larger effect on soils shows .The increase of the effect on soils is greater with the increase of the friction coefficients of soils .