Effects of rock fragment content on erosion characteristics of spoil heaps under multiple rainfall events

To examine the effects of rock fragment contents of spoil heaps on hydrological and sediment yielding processes,multiple simulated rainfall experiments were conducted in the laboratory. The results showed that,as the rock fragment content in the spoil heap increased,the duration of runoff generation on the slope was prolonged,the rate of runoff decreased linearly,and the soil detachment rate decreased. Under multiple rainfall events,rock fragments in spoil heaps decreased sediment yield primarily through the effects on runoff generation duration,runoff rate and rock fragment cover,and principal component regression could express the relationship between these factors and the average soil detachment rate. Under a certain rock fragment content,as surface soil was detached under multiple rainfall events,the rock fragment cover increased,which caused the soil detachment rate to decrease exponentially and also had a significant functional relationship with the accumulated total soil loss. The erosion reduction effect of the rock fragments contained in the spoil heaps can provide an important reference for water and soil conservation of the underlying surface of production and construction projects.