耦合结构面剪胀的嵌岩桩侧摩阻力分析

 嵌岩桩桩–岩界面受力剪切机制通常包括滑动剪胀及剪切滑移两部分，滑动剪胀导致桩–岩界面法向应力显著增大。Serrano法计算嵌岩桩侧摩阻力没有考虑桩–岩界面剪胀效应的影响，从而使得其计算结果比现场实测值偏保守。基于常法向刚度(CNS)条件下结构面剪切力学特性，充分考虑岩性、桩径以及施工等因素对嵌岩桩受力特性的影响，在对既定粗糙度结构面剪胀产生的法向应力增量实现量化分析的基础上，通过耦合结构面剪胀对Serrano法进行修正。计算结果表明，修正的Serrano法计算所得嵌岩桩侧摩阻力明显高于Serrano法，也更接近于现场实测。修正的Serrano法完善嵌岩桩侧摩阻力的理论计算。

SIDE FRICTION ANALYSIS OF ROCK-SOCKETED PILE CONSIDERING DILATANCY OF STRUCTURAL PLANE

The shear mechanism of pile-rock interface of rock-socketed pile includes sliding dilatancy and shear slipping；the sliding dilatancy causes the normal stress increase significantly. The method for calculating the side friction of rock-socketed pile proposed by Serrano did not consider the effect of pile-rock interface dilatancy，which makes it more conservative than the measured value. Based on the results of the structural plane shear tests under constant normal stiffness(CNS) condition，which fully consider the effect of lithology，pile diameter and construction on the mechanical characteristics of rock-socketed piles，and the quantified values of the normal stress increment produced by dilatancy are achieved；then Serrano?s method is modified by considering the quantified normal stress increment values. The analytical results show that，the side friction values calculated by the modified method exceed the values calculated by Serrano?s method；and the former are also closer to the field measured values. It is confirmed that the modified Serrano?s method is more reasonable.