内力测量新技术在灌注桩试验中的应用研究

Research on Application of New Technology of Internal Force Measurement in Cast-in-place Concrete Pile Test

在灌注桩试验中,引入钻孔数字测井系统和滑动测微原理相结合的新技术,用于成孔质量检测和桩基内力测量。在竖向静载试验中,根据钻孔数字测井系统所得的孔径实测数据,对滑动测微计的应变实测值进行断面修正,通过进行回归光滑处理,得到了弹性模量随应变量级之间的关系,从而能够计算出每级荷载下的桩身轴力、桩侧摩阻力以及桩端阻力;在水平静载试验中,以滑动测微计的应变实测值为基础,通过分析迎力面拉应变曲线和背力面压应变曲线,求得了最大弯矩点以及极限水平荷载值。

In cast-in-place concrete pile test, the new technology, combining with the system of bore-forming digital logging and principle of sliding micrometer, was introduced, and applied in quality inspection of bore forming and measurement of internal force in pile. In vertical static load test, based on the measured data of pile diameter from the system of bore-form- ing digital logging, the measured strain values obtained from sliding micrometer were modified by the section method; thus, the relationship between elastic modulus and strain magnitude can be calculated according to the smooth regression; there- fore, the axial force of pile, skin friction of pile, and tip resistance can be figured out. In horizontal static load test, based on the measured strain values from sliding micrometer, the point of maximum bending moment and value of ultimate lateral load can be gained according to the analysis of tensile strain curve in bearing surface and compressive strain curve behind the back of bearing surface.