隧道开挖对临近不同相对刚度比桩基影响研究

为了系统研究桩土的相对刚柔性对隧道开挖引起的邻近桩基附加位移和附加内力的影响规律,本文采用三维数值分析方法,通过变换桩基弹性模量、半径和桩长而获得不同桩土相对刚度比,对比分析了隧道开挖时不同桩土刚度比的桩基附加位移和内力的变化规律。结果表明:在桩长一定的情况下,桩土刚度比越大,隧道开挖对桩基产生的附加内力越大,附加位移越小,尤其是桩基的竖向附加沉降量随桩土刚度比的减小而急剧增大;在弹性模量和桩径一定的情况下,桩土刚度比越大,桩基产生的附加内力越小,位移越大。因此,隧道开挖时需对不同刚柔性桩基加以区别保护,研究成果可为隧道施工和设计提供参考。

The influence of tunneling on adjacent piles with different stiffness ratios

In order to study the influence of tunneling on adjacent rigid-flexible piles,a three-dimensional numerical analysis method is adopted.The different stiffness ratios of pile and soil are obtained by changing the pile’s elastic modulus,radius or length.The additional displacement and inner force due to tunneling are compared with respect to different stiffness ratios.With a constant length for a pile,the additional inner force increases with the stiffness ratio while the additional displacement decreases.Particularly,the additional vertical settlement increases rapidly with the decrease of stiffness ratio.With a constant elastic modulus and diameter,the additional inner force decreases with the stiffness ratio while the additional displacement increases.Therefore,different protection measures must be adopted for rigid-flexible piles according to the stiffness ratio during the course of tunneling.The conclusions can be useful for construction and design of tunnels.