Device and method for detecting depth of sand bag well

The invention discloses a device and a method for detecting the depth of a sand bag well. The device comprises a target object capable of producing a magnetic field, and a probe matched with the target object, wherein the probe can sense a magnetic field signal in an area covered by the magnetic field. The method comprises the steps of (1) filling a sand bag, presetting the target object capable of producing the magnetic field at the end part of the sand bag, and putting the end, provided with the target object, of the sand bag into the bottom part of the sand well; and (2) forming a detection hole parallel to a sand well hole in an earth surface area corresponding to the magnetic field covering area on the periphery of the sand well hole, arranging the probe for sensing the magnetic field signal in the detection hole, sensing the magnetic field signal through the probe, recording a depth position of the magnetic field signal, and accomplishing the detection of the depth of the sand bag well. The device and the method for detecting provided by the invention are easy to operate, simple in embedded facilities, and accurate in detection result, can avoid directly contacting the sand bag so as not to influence the quality of the sand bag well, and have important positive effects on promoting the construction quality control of the sand bag well.