基于结构动力修改的桩基检测方法

采用结构动力修改技术研究桩身损伤检测，将其转化为在一定约束条件下拟合桩顶频响函数的优化问题。用遗传算法加以求解。文中给出的数值模拟试验和工程应用实例，显示该方法能在较大范围内可靠地反演出桩身横截面积、桩长、波速等参数，达到检测桩身缺陷的目的，实现测试和分析一体化，使桩基检测易于进行并且结果实用可靠。

A pile testing method based on structural dynamic modification

This paper presents a pile testing method using the technique of structural dynamic modification. Some methods such as stress wave testing have been employed to detect the pile's integrity as the piles are placed underground and cannot be observed directly. But there are still some challenges in the field. In order to reduce the inevitable potential error caused by reading from the original signal directly, the structural dynamic modification schedule is adopted to make use of as much as possible information carried by system's actual response and to seek a more ideal identification. First, a priori parametric analytical model (FEM model) that describes the response of a pile-soil system is assumed, and then the system's actual response is measured experimentally. Through some correlation of the analytical model with the measured data the parameters of the analytical FEM model are updated. The inverse-problem is translated into an optimization problem which minimizes the error function of frequency response in certain constraint conditions and is solved using genetic algorithm. Some numerical simulations and engineering examples (which are applied in a field test) are listed in the paper and all show good results. The present method can effectively determine the parameters of piles such as cross area distribution, total length, wave velocity and so on in a wide range. It makes the work of pile testing easy to do and has more practical reality. In addition, it means a type of test-analysis integration which meets the requirment of model validation.