Research On Underground Three-dimensional Displacement Measurement Based On Multi-inductance Coil

The frequent occurrence of geological disasters will cause great harm to people's lives and property,and also affect the development and construction of society.The common geological disasters are landslides,mudslides,etc,before occurring,are often accompanied by varying degrees of geotechnical deformation.Therefore,monitoring geotechnical deformation is an important approach to prevent and study geological hazards.If it is possible to conduct in-depth monitoring of parameters,such as,horizontal displacement and vertical displacement of underground rock and soil in real time.To some extent,this can predict the occurrence of geological disasters,release early warning information and organize crowd evacuation,thereby reducing the losses caused by geological disasters to people.However,many methods and technologies are difficult to monitor the underground displacement,because the monitoring environment is located in the interior of rock and soil.Therefore,the development of underground displacement monitoring technology is relatively slow,making monitoring methods with low accuracy,high cost,and non-automated issues.Common underground displacement monitoring methods at home and abroad mainly include TDR technology,borehole inclinometer technology,settlement meter and extensometer,but these methods have their own application areas and deficiencies.Therefore,this paper examined a multi-transverse coil-based underground threedimensional displacement measurement method combined with the current monitoring way.In this paper,the three-dimensional displacement measurement of underground is studied by using the principle of coil mutual inductance,horizontal,vertical displacement and direction angle of underground are monitored by the symmetrical structure of the measuring unit.The measurement system consists of several identical measurement units connected in series via RS485 fieldbus.The measurement unit includes the mutual inductance coil and the hardware circuit.The mutual voltage of the coil will change followed the change of the relative position between two adjacent units.So the measurement of the mutual voltage in the measurement process is used to reflect the relative three-dimensional displacement between two adjacent units by measuring all phases.Then,the relative displacement between two adjacent units will achieve the measurement of the entire underground rock and soil displacement.At the same time,build an experimental platform with 7SC405 motion controller as the core and write the upper computer program to automatically collect a large amount of voltage data.Using the obtained voltage value to establish the mathematical model through the contour,the measurement of the underground displacement is finally achieved.The maximum error of the predicted value of the vertical displacement and horizontal displacement of the model constructed by the contour method is 2mm,and most of the errors are 1mm.Compared with other methods of underground displacement measurement,this method can be more comprehensive monitoring of the measured object and has a larger measurement range as well as more applications.