自平衡法和高应变检测在码头灌注桩中的应用

Application of self-balanced method and high strain detection of cast-in-place pile in wharf

海南某高桩码头工程地质条件特殊,表面覆盖硬岩层,下部为黏土层,码头基础采用灌注桩结构,以硬黏土层为持力层。施工后分别采用自平衡法静载试验和高应变法检测桩基承载力,将检测结果与规范理论计算结果进行比较。结果表明,通过自平衡检测的荷载-位移关系曲线判断,桩端依旧处于弹性阶段,并根据在加载过程中桩身轴力沿桩身轴向的分布情况,可分别判断各桩侧摩阻力、端承载力的发挥值,从而判断桩阻力并没有全部发挥,桩基的实际极限承载力大于试验值。高应变检测法检测桩侧摩阻力结果大于理论计算结果,桩端承载力小于理论计算结果,总桩基承载力二者比较接近,因此可以作为静载试桩的辅助验证。在港口码头工程中采用自平衡静载测试法,并用高应变检测法进行验证,可以解决水域条件下大质量桩基承载力的检测问题。

The geological conditions of a high pile wharf project in Hainan are special,with hard rock layers covering the surface and clay layers below.The wharf foundation is adopt cast-in-place piles,with the hard clay layer as the bearing layer.After the construction of the project,static loading tests using self-balanced method and high strain method are carried out to detect the bearing capacity of the pile foundation,and the detection results are compared with the theoretical calculation results by the code.The results show that by using the load-displacement relationship curve of self-balanced test,it can be determined that the pile end is still in the elastic stage.Based on the distribution of the pile axial force along axial direction during the loading process,the values of the lateral friction resistance and end bearing capacity of each pile can be determined separately,and the pile resistance is not fully exerted and the actual ultimate bearing capacity of the pile foundation should be greater than the test value.According to the results of the high strain detection method,lateral friction are greater than the theoretical calculation results,and the pile end bearing capacity is smaller,while the total pile foundation bearing capacity is relatively close to the two,so it can be used as an auxiliary verification for static load pile testing.The use of self-balanced static loading test in port and wharf engineering,using high strain testing method for verification,can solve the problem of detecting the bearing capacity of high-mass pile foundations underwater conditions.