陕北黄土地区旋挖钻孔桩荷载传递特性研究

摘要

为了研究旋挖钻孔灌注桩的承载性能，明确其与泥浆护壁钻孔灌注桩的区别，结合陕西省某高速公路扩能工程桩基试验段的桩基静载荷试验，对旋挖钻孔灌注桩的荷载传递规律和桩侧摩阻力发挥特性进行分析，认为旋挖钻成孔时无需护壁泥浆，避免了桩侧泥皮的形成；同时形成的孔壁粗糙，加强了桩土的咬合作用，提高了桩侧阻力的发挥，降低端阻比。结合荷载沿桩身传递规律对单桩极限承载力进行预测，采用双曲线法对荷载－沉降曲线进行拟合，拟合效果良好，单桩极限承载力预测结果准确。%In order to study the bearing capacity of revolving digging cast-in-place bored piles and clear the difference between those piles and bored piles with Shury wall,this article analyzed the load transfer behavior and pile shaft resistance action with the aid of pile foundation static load test of an expressway expansion project test section in Shaanxi.The experimental results show that it does not form pile shaft mudcake because mud is not needed during holing by churning driven.Since the wall of hole is rough,the friction between pile and soil is strengthened.This friction can enhance the action of pile shaft resistance and reduce the ratio of pile tip resist-ance and working load.Combined with the behavior of load transfer along pile shaft,the ultimate bearing capacity of single pile was predicted.The hyperbola was used to fit the curve of load-settlement.The results show that the fitting effect is good and the prediction result of ultimate bearing capacity of single pile is accurate.