Low-strain testing device for detecting integrity of ultralong bored concrete pile

The invention provides a low-strain testing device for detecting integrity of an ultralong bored concrete pile. The testing device comprises a plurality of relay sensors, a plurality of sensor protecting bodies, a signal cable, a pile top sensor, a force hammer and an engineering detector. The testing device has the following advantages: the testing device detects the integrity of the bored concrete pile by embedding the relay sensors in the appropriate parts of the pile body and adopting the methods of field data acquisition and signal analysis, so not only can the stress wave propagation distance be reduced, but also the structure of the pile body can not be damaged, thus ensuring the quality of the pile body and the safety of the upper structure; the testing device has high detection precision, high detection speed, low impact on the construction process, simple structure and low detection cost; and besides, the device can be applicable to the piles with different length by adjusting the quantity of the embedded sensors, so the device can solve the problem that the integrity of the long piles with length being more than 50m can not be accurately detected at present and has wide range of application.