Three-Dimensional Measuring Device and Method of Underground Displacement Based on Double Mutual Inductance Voltage Contour Method

Abstract

Landslide is a very common and destructive geo-hazard, and displacement monitoring of it is integral for risk assessment and engineering prevention. Given the shortcomings of current landslide displacement monitor technologies, a new three-dimensional underground displacement monitoring technology is proposed based on the double mutual inductance voltage contour method. The underground displacement measuring device mainly consists of an information processing unit and sensing array, connected by power and RS-485 communication lines. An underground displacement measurement model to convert the double mutual inductance voltages and the inter-axis angle into the relative displacement between adjacent sensing units is established based on the interval-interpolation and contour-modeling. Under the control of the information processing unit, the relative displacement between any two adjacent sensing units can be calculated through the underground displacement measurement model, so as to obtain the total displacement from underground depth to surface, and the measurement data can be further sent to the Internet of things cloud platform through the 4G module; thus the remote real-time monitoring of underground displacement three-dimensional measurement for the rock and soil mass from underground depth to the surface is realized. The measurement model is verified by building an experimental platform to simulate the underground displacement of rock and soil mass. The experimental results show that for each measuring unit, when the horizontal displacement and vertical displacement are within the measurement range of 0–50 mm, the maximum measurement error will not exceed 1 mm, which can meet the accuracy requirements of underground displacement monitoring of landslide.

Low-Power and Wireless Communication Research on Underground Displacement Three-Dimensional Monitoring System

“…In two adjacent coils, when the current in one coil changes, an induced electromotive force is generated in the adjacent coil, which is called the mutual inductance phenomenon. The principle of dual mutual inductance measurement proposed by our research group [ 11 , 12 ] is based on the application of the mutual inductance phenomenon. Figure 2 shows the principle diagram of dual mutual inductance voltage measurement.…”

“…However, these methods cannot achieve the monitoring of underground three-dimensional displacement of rock and soil mass and cannot truly reflect the evolution process of underground rock and soil mass. In recent years, our research group has integrated multiple magnetoelectric sensing mechanisms such as electromagnetism, mutual inductance, and magnetoresistance, combined with dual mutual inductance equivalent modeling, a flexible sensing array, and integrated sensing technology, to propose a new type of underground displacement remote monitoring system [ 11 , 12 ], which can automatically, in real-time, and accurately monitor the underground three-dimensional displacement of rock and soil mass. Through the study of the above literature, the advantages and disadvantages of existing underground displacement detection methods are shown in Table 1 .…”

“…The original system [ 11 , 12 ] used an RS485 bus to connect the ground management terminal and hundreds of sensing units for communication. If the 485 communication module of any sensing unit has failed for some reason, it will cause other sensing units to be unable to continue 485 communication.…”

“…In order to meet the special needs of complex geotechnical environments deep underground, it is necessary to study wireless communication technology and the network topology structure suitable for an underground displacement three-dimensional monitoring system. In the initial state, considering the structure of the sensing units, the relative displacement between the circuit boards of the two sensing units is generally around 10 cm [ 12 ]. At the same time, based on the author’s extensive previous research, for the majority of geological disasters, the relative displacement between any two sensing units is not expected to exceed 15 cm.…”

Research on the Landslide Prediction Based on the Dual Mutual-Inductance Deep Displacement 3D Measuring Sensor

“…In order to overcome these questions mentioned above, in previous work, a new deep displacement measuring sensor based on dual mutual inductance [45] has been developed. The whole sensor adopts a sensing array structure, thus, the sensor can deform synchronously with the surrounding rock and soil mass, and the distance and direction of the sensing unit are approximately equal to the displacement of the surrounding rock and soil mass.…”