锚杆锚固质量无损检测几个关键问题的研究

对近年来有关锚杆无损检测的研究工作进行总结.通过理论分析和实验研究,对锚杆锚固质量无损检测中的几个关键问题进行较为深入的探讨研究:通过逐渐改变锚杆自由段和锚固段相对长度的方法,研究底端反射的变化规律,得出锚固长度小于3/4首波波长时底端反射不明显的结论;通过对锚固体控制体积的力学分析,用水泥砂浆在不同养护时间内的固化程度和对杆体的握裹强度模拟锚固介质的黏结强度,得出固结波速与锚杆杆体、锚固介质及围岩之间的黏结强度有关的结论;通过对承载条件下锚杆动态响应的分析和实验研究,得出锚固体系的基频和动刚度与荷载呈幂函数增长的规律,以及锚杆的动态响应与锚杆的工作荷载与极限承载能力的相对大小显著相关的结论.研究结果可用于锚杆无损检测的工程实践.

STUDY ON SEVERAL KEY ISSUES IN NONDESTRUCTIVE DETECTION OF BOLT BONDING INTEGRITY

The latest researches on nondestructive detection of rock bolt bonding integrity are summarized.By means of theoretical analysis and laboratory research,several key issues in nondestructive detection,i.e.end reflection,consolidation wave and dynamic response of rock bolt under loading,are discussed.With the variation of free part length of different grouted rock bolts,the fact is found that the end reflection is not very obvious when the grouted length is shorter than 3/4 wave length of input signal.If changing the grout concrete strength,the relationship between consolidation wave speed and bolt bonding integrity is achieved.In addition,the testing rock bolt response under loading and the relationship between basic frequency of dynamic response and loading level are also gained.All of these relationships are valuable in engineering practice.