大吨位嵌岩桩承载力现场足尺试验研究

Field full scale test on large tonnage bearing capacity of rock-socketed piles

试验方法的比选、试验设施的选取和设置对现场足尺试验的试验效果影响极大。根据广东省珠江口大型跨江工程试桩要求,详细分析了试桩形式、试桩尺寸、试桩方法等要素比选过程及确定方法。根据不同区位试桩桩径、最大加载量要求等,进行了试验方法的比选。详细介绍了自平衡方法中,荷载箱埋设位置的确定方法,以及自平衡法加载效果与试验需求符合性分析方法。通过分析结果可见,荷载箱加载能力随桩径、工作油压的增大而增大,但桩径小于1.50m时,增大幅度不明显;但桩径大于1.5m时,自平衡法加载能力显著增大,说明大直径基桩试验中,自平衡法加载优势较明显。该工程足尺试桩基于这些成果进行,验证了基桩整体承载性能。

The comparison and selection of test methods, the selection and setting of test facilities have great influence on the test effect of full-scale test. According to the pile test requirements of an engineering over the Pearl river in Guangdong, China, it was analyzed in detail such as the comparison and selection of test pile form, test pile size, test pile method. According to the requirements of pile diameter and maximum load in different locations, the test methods are compared and selected. This paper introduces in detail the method of determining the position of the load box in the self balancing method, and the method of analyzing the compliance between the loading effect of the self balancing method and the test requirements. The analysis results show that the loading capacity of load box increases with the increase of pile diameter and working oil pressure, but the increase is not obvious when the pile diameter is less than 1.50 m and when the pile diameter is greater than 1.5 m, the loading capacity of load box method increases significantly,which indicates that the loading advantage of self balancing method is obvious in large diameter pile test. Based on these analysis results, the test pile of the engineering is carried out to verify the bearing performance of pile foundation.