中文摘要：

通过对某高速铁路特大桥群桩基础进行三维非线性有限元分析,并结合现场试验得出的规律进行相应的对比分析,研究了软土地层桥梁群桩基础桩身轴力、桩侧摩阻力、基底土体附加应力、孔隙水压力分布、超孔隙水压力消散和群桩基础荷载沉降规律。计算结果表明,基桩所承受的轴力,角桩〉边桩〉中心桩,角桩和边桩的轴力沿桩身减小的幅度较大,而中心桩的轴力沿桩身减小的幅度稍小;各基桩桩侧摩阻力的发挥情况,侧摩阻力值总体上呈角桩〉边桩〉中心桩,相对滑移量基本呈上大下小的形态,即桩身上部桩-土之间产生的相对滑移量较中下部要大;外荷载作用下产生的土体附加应力和超孔隙水压力主要集中在承台底以下土体的一定范围内,其衰减梯度沿深度方向逐渐降低,随着固结时间的延长,群桩基础沉降达到稳定。

英文摘要：

A three dimensional nonlinear finite element model of pile group foundation of a high-speed railway bridge was built.Combined with the corresponding data obtained from field tests,the rules of pile axial force,pile side friction force,soil additional stress,pore water pressure distribution,excess pore water pressure dissipation and settlement of pile group foundation were analyzed.The calculation results show that the axial forces of corner piles are larger than the side piles which are larger than the center piles;and the axial forces of corner piles and side piles reduce greatly along the pile body;and the axial forces of center piles decrease slowly.Moreover,the regular pattern of pile side friction is that the pile side friction measurement of corner piles are larger than the side piles which are larger than the center piles generally;and the amount of relative displacement between pile and soil is bigger on the upper and less on the lower.That is to say,the amount of relative displacement between pile and soil on the upper of pile is larger than on the middle and lower of pile.Furthermore,the soil additional stress and excess pore water pressure generated by external loads mainly concentrate in soil under the pile cap within a certain range;and their attenuation gradients decrease along the depth gradually.With the increasing of the consolidation time,the settlement of pile group foundation arrives to be stabilized.