磁测井法检测基桩钢筋笼长度的应用分析

Application Analysis of Testing the Length of Reinforcement Cage in Foundation Pile by Magnetic Logging Method

基桩中的钢筋笼为铁磁性物质,其端部和接头处本身磁场和地磁场的矢量叠加会产生磁场变化。本文结合工程实例,研究了灌注桩、管桩桩长范围内的磁场变化规律。结果表明,在灌注桩钢筋笼端部、管桩法兰盘位置磁场强度均出现极值点及拐点,对应的磁场梯度也出现极值点。因此根据这些磁场变化的位置,可以测得基桩中的钢筋笼长度和接头位置,同时工程实例验证也表明该方法测定的结果准确可靠,可为行业相关工程提供借鉴。

The reinforcement cage in the foundation pile is ferromagnetic material,and the magnetic field changes will be caused by the vector superposition of the magnetic field and the geomagnetic field at its end and joint.In this paper,the variation rule of magnetic field in the length range of cast-in-place pile and pipe pile is studied combining with engineering examples.The results showed that the extreme point and inflection point of the magnetic field intensity appeared at the end of reinforced cage for cast-in-place pile and flange for pipe pile,and the corresponding extreme points of magnetic field gradient also appeared.Therefore,according to the location of these magnetic field changes,the length of the reinforcement cage and the location of the joint in the foundation pile can be measured,and the engineering example verification also shows that the measurement results of the method are accurate and reliable,which can provides reference for related projects in the industry.