Underground three-dimensional displacement measurement system and method based on double mutual inductance equivalent voltage

An underground displacement three-dimensional measurement system based on a double mutual inductance equivalent voltage, comprising an on-site measuring device and a remote monitoring system, the on-site measuring device and the remote monitoring system are connected via a wireless communication network, wherein the on-site measuring device comprises N integrated underground displacement measurement sensing units and one underground displacement information lumping unit connected in series by means of a power line and a communication line, the N integrated underground displacement measurement sensing units are serially connected and then are connected between an underground immovable layer and a ground, wherein:

• each of the integrated underground displacement measurement sensing units comprises an external PVC sleeve, a cylindrical air-core coil, a cylindrical magnetic core coil, and a PCB, the cylindrical air-core coil and the cylindrical magnetic core coil are both installed in the PVC sleeve, the cylindrical air-core coil is located around an inner surface of the PVC sleeve, the cylindrical magnetic core coil is located in the middle of the cylindrical air-core coil, the cylindrical air-core coil, the cylindrical magnetic core coil, and the PVC sleeve share a same central axis, and the PCB is arranged in a middle portion of the PVC sleeve in an axial direction.