Author(s): Xiaogang Wang; Yun Li; Guoxiang Xuan; Andre Rene Koelewijn
Keywords: Earth-rock dam; Overtopping; Breach formation time; Prediction
Abstract: According to the data from U. S. Bureau of Reclamation, when warning time of dam breach is more than 90 min, the mortality of downstream people is about 0. 04% . When the time is less than 90 min and 15min, the mortality is about 13% and 50% respectively. It can be seen the warning time of dam breach is very important to emergency rush. Unfortunately, the prediction of breach formation time is very difficult because there is very little valid data of dam breach. It is very hard to deal with scare effect for dam breach experiments. Establishing a valid numerical model of dam breaching is also difficult because no equations can describe the complex process of dam breach. Based on the statistical methods the relationships were analyzed between dam breach time and dam parameters, index of breach for earth-rock dam breach due to overtopping. It was presented the driving force of breach was dominant for big reservoirs or high dam when overtopping happened. The breach formation time will be short. For small reservoir or short dam the difference between driving force and passive force is not obvious. The breach formation time is uncertainty when overtopping happened. In this paper a hypothesis was introduced. The soil factor from Renzhi Xie was one-to-one correspondence to soil erosion resistance from Briaud. Base on this hypothesis a prediction method of breach formation time was presented. According to the results, this method has a good prediction and the total accuracy is about 81. 81% (The accuracy is only for discrimination of dam failure because of no valid breach formation time).