O-Cell法在桩极限荷载试验中的运用以及平衡点的确定

The Application of O-Cell Method in Pile Ultimate Load Test and the Determination of Equilibrium Point

为了准确确定土层、岩层的物理参数以及单桩承载力,澳门名胜酒店项目采用单桩多循环O-Cell试桩法。通过经验估算法确定平衡点位置,将一次荷载从0加到峰值并卸载到0视为一个循环,试验共采用了3次循环,3次循环加载的峰值分别为桩工作荷载的150%、200%、300%,其中第三次循环加载进行到271%时,上部桩被顶起试验结束,通过3次实测数据可求解桩侧摩擦力以及试桩极限承载力。进一步分析可知,平衡点位置的确定是决定整个O-Cell试桩法可靠性以及准确性的关键因素,从而提出将传统经验值法和数值模拟相结合确定平衡点位置的方法。

In order to accurately determine the physical parameters of soil layer and rock stratum and the bearing capacity of single pile,the multiple-cycle O-Cell test method of single pile was adopted in the Macao Resorts Hotel project.The location of the balance point is determined by empirical estimation method,and a load from 0 to peak and unloading to 0 is regarded as a cycle.Three cycles are adopted in the test,and the peak values of the three cyclic loads are 150%,200%and 300%of the working load of the pile respectively.When the third cyclic load reaches271%,the jacking test of the upper pile ends,and the pile side friction force and ultimate bearing capacity can be solved by three measured data.Further analysis shows that the determination of the balance point position is the key factor to determine the reliability and accuracy of the whole O-Cell pile test method.Therefore,a method combining traditional empirical value method with numerical simulation is proposed to determine the balance point position.