Study on slab repairing for a ash dam in Fengtai Power Plant in Inner Mongolia

Many dams of coal ash storage yard in power plants in northern China are made of coal fly ash.During winter a thick ice layer would be formed inside the dam body due to negative temperature,resulting in frost heave.Ice would push and squeeze concrete protection slabs on the ash dam,causing slabs and geotextiles to break and collapse.When temperature rises,water waves in the reservoir would wash away ashes from dam through the outworn geotextiles.The author analyzed the damaging causes in terms of slabs material and characteristics of ice layer freezing and studied the existing repairing materials and repairing technology.A new method of using PVC covering material on the slabs was put forward to avoid ice extrusion and damage.In March of 2006,a test was conducted to repair a 200m long dam seriously damaged in the Fengtai Power Plant in Inner Mongolia by applying the method.Field observations in the winter of that year and 3 years latter showed that the material played a part in resisting frost heave and ice extrusion without frost heave damage.The coal ash storage yard was in normal operation.