塑料排水板堆载预压处理软土地基对临近桥梁桩基的影响研究

对某软土地基的塑料排水板堆载预压进行了桩基沉降和地基土孔隙水压力监测,使用ABAQUS有限元分析软件建立了三维有限元分析模型,现场实测数据结合有限元模型分析结果,系统研究了塑料排水板堆载预压处理软土地基对临近桩基的影响,研究结果表明:堆载预压初期孔隙水压力急剧增加,前期孔隙水压力消散较快,后期逐渐减小;临近桩基的变形主要以水平变形为主,竖向位移较小,随着孔隙水压力的消散,桩身水平位移随时间逐渐减小;堆载预压对临近桩基的不利影响主要发生在堆载预压初期,该阶段桩侧被动土压力和桩身弯矩均最大,且都位于桩顶处,随着孔隙水压力的消散,桩侧被动土压力和桩身弯矩都随时间逐渐减小;桩身最大水平位移和最大弯矩都随堆载预压距离的增加而急剧减小,因此在桩基附近进行塑料排水板堆载预压处理软土地基时,应保持合适的堆载预压距离.

Studies on the Influence of PVD Improved Soft Soil on theAdjacent Bridge Piles

In-suit measurement of the settlement and the pore water pressure of soft soil ground was carried out for a prefabricated vertical drain (PVD) improved soft soil ground.A 3D finite element analysis model of PVD improved soft soil ground was established by the ABAUQS.Comparison of the numerical simulation and the in-suit measurement was used to study the influence of PVD improved soft soil ground on the adjacent bridge piles.Research results indicate that the pore water pressure increases rapidly at the preliminary stage,and dissipates faster at the early stage than the later stage;the horizontal displacement is main for the adjacent piles,while the vertical displacement is very small,and the horizontal displacement decreases gradually with the pore water pressure dissipating;The negative influence of PVD improving soft soil ground on the adjacent piles mainly occurs at the preliminary stage when the passive earth pressure and the bending moment of pile are the maximum at the pile top,and decreasing gradually with the pore water pressure dissipating;The passive earth pressure and the bending moment of piles are decreasing sharply with the distance between the PVD area and the adjacent piles,so it is supposed to keep suitable distance when using the PVD method.