Structural and ground deformations due to mining induced subsidence

Ground deformations induced by mining related subsidence can cause considerable damage to buildings. To study the mechanisms of ground and structural deformation during subsidence, twelve foundations were constructed over an active longwall panel. Use of the tiltmeter, the inclinometer, the pressuremeter, and soil strain gages was made to measure the structural and ground response during subsidence. The measured response of both the ground and structures is analyzed in terms of deformation parameters such as vertical subsidence, slope angle, curvature, and strain.

It was found that during active longwall mining, the structural footings in the centerline zone experience three phases of tension, compression, and tension sequentially. This was confirmed by the slope angle and curvature data obtained from both the inclinometer and tiltmeter systems. The strains in the free-field and at the soil-footing interface also confirm the three phases of subsidence in the centerline zone. In the tension zone, the footings experience only tension. It was concluded that the tiltmeter system yields more consistent slope and curvature data than the inclinometer system.