Seismic resistance of sludge collector enclosing dams erected from the waste product – phosphogypsum

Abstract

The results of experimental studies of the model behavior under seismic effect in a centrifugal testing installation are given in the paper. The goal was to study the deformability and stability of slopes of a given configuration made of phosphogypsum and to substantiate the possibility of using phosphogypsum in erecting enclosing dams of sludge collectors located in seismic regions. The experiments on models are based on the centrifugal modeling method, which involves the change in gravity field of the model. The models were tested at a stabilized and unstabilized state of phosphogypsum. Models stabilization was achieved by centrifugation for 8-25 min. The model was considered stabilized when its deformation did not exceed 0.01 mm. In a stabilized state, a fragment of the dam slope made of phosphogypsum in a water-saturated state at a slope steepness m=2, m=3 and in a dry state at m=2 was investigated. In an unstabilized state, the models of dams made of phosphogypsum were studied in a water-saturated state with a slope steepness m=3, and a dam fragment at m=3 in a water-saturated state with horizontal and vertical sand drainage layers. As a result of studies of seismic stability of dam fragments made of phosphogypsum, the following was established: the overall stability of dams made of phosphogypsum (in a stable state) under seismic effect of up to 9-10 points is fully ensured both in a dry and water-saturated state. Horizontal and vertical interlayers increase the slope stability of the dam model made of phosphogypsum in a water-saturated state; the slopes were stable after a dynamic impact of 9 point even in unstabilized states. Drainage layers accelerate the consolidation of phosphogypsum, and this naturally increases the seismic resistance of dams.