Zigbee based Wireless Data Acquisition System for monitoring of partition stability above old underground coal workings

Conversion of old underground workings into opencast mines leads to rock displacement, collapse of partition, and slope failures some times. Continuous monitoring of slopes and partition is required to maintain the stability over old workings. Wireless sensor network is more suitable method for continuous monitoring, and it is cost-effective, two-way communication, and provides real-time monitoring and analysis of data. In this paper, development of a low-cost Zigbee based Wireless Data Acquisition System (WDAQ) is described. Field investigations were carried out in an opencast coal mine in south India to assess the strain and deformation for different partition thicknesses of 4.12m, 5.91m, 6.86m, 7.91m, 10.21m and 12.10m over old underground workings, due to the external load caused by the movement of Heavy Earth Moving Machinery (HEMM). Maximum strain and deformation were 387 x 10(-6) and 2.41 mm for 4.12 m partition, respectively. It can be observed that the strain and deformation are decreased with increased partition thickness. This paper also describes that the validation of data based on Zigbee based WDAQ with conventional method of monitoring as well as numerical modeling. The data obtained using WDAQ is in close to the other two methods. The variation is around 5-19%.