Experimental study of deformation and stability of dams built of phosphogypsum under seismic impacts

Abstract

The article presents the results of experimental studies of the model behavior under seismic influences. The conditions for ensuring the seismic resistance of phosphogypsum dams were investigated and established by testing the models on a vibration platform. The purpose was to study the deformability and stability of slopes of a given configuration built of phosphogypsum and to substantiate the possibility of using phosphogypsum to construct enclosing dams of sludge tanks located in seismic regions. The tests were conducted on small-scale models on a horizontal vibration platform in laboratory conditions. The methods of research using the vibration platform and the accepted modeling parameters were discussed. Dihydrate phosphogypsum with an optimal moisture content of 22-23% was used to construct the models. In total, 2 groups of prototypes were tested; they differed from each other only in the slope ratio. Models of the 1st group were tested without water. Models of the 2nd group were tested after wetting their materials to an average of 32 - 40%. To do this, water was filled in into the tank to the crest level, and the models stayed in this state for a week. Each model in both groups was tested for dynamic impacts with an earthquake intensity of 6-9 points. As a result of the studies on the seismic stability of dam fragments made of phosphogypsum, it was established that the enclosing dams of sludge tanks (built from phosphogypsum with optimal moisture content and its layerby-layer compaction up to 1.25 g/cm3, when the slope ratio was no steeper than m=3), have the necessary seismic resistance during earthquakes with an intensity of 7 -9 points. Based on the generalization of the data of model studies, the diagrams of the acceleration distribution in the height of the models were obtained. The diagrams of the acceleration distribution in height obtained in the experiments indicate the amplitude attenuation of the model vibrations from the base to the crest zone.