Underground geotechnical displacement measurement method and device based on Hall effect

The invention discloses underground geotechnical displacement measurement method and device based on Hall effect. The device is formed by connecting a plurality of measurement units in series, and the lower surface of each measurement unit is parallel to the upper surface of the other adjacent measurement unit. In each measurement unit, the lower surface is provided with a permanent magnet or an electromagnet, the upper surface is provided with at least 3 Hall sensors, each measurement unit is connected with a 485 bus into a string vertically through a power line, the whole string of measurement device is vertically inserted into a rock stratum, and the output voltage of the measurement device is transmitted into a singlechip through an analog-to-digital conversion chip. When the adjacent measurement units perform relative displacement, the position of the Hall sensor on one of the measurement unit changes relative to the permanent magnet or the electromagnet on the other measurement unit, thereby the output