Author(s): Yun Li; Xiaogang Wang; Huojian Liu; Guoxiang Xuan; Andre Rene Koelewijn
Keywords: Earth-rock dam; Overtopping flow; Numerical simulation; Hydraulic characteristics
Abstract: Dam breach is hot issues at present. It’s very important to study the flow characteristics on downstream slope dam for knowing dam breach mechanism, carrying out flood control and rush emergency. In this paper, physical tests and numerical simulation have been done to study the distribution of water depth, velocity, pressure and shear stress on downstream slope dam. The distribution rules of these variables were presented. According to the results, the water depth decreases gradually, the velocity and shear stress increases gradually along downstream slope. The bigger overflowing depth is the bigger water depth, velocity and shear stress on downstream slope. There are two inflexion points of shear stress at abutment and dam toes respectively. The pressure is negative at abutment and positive at dam toes. The absolute pressure values of these two positions are much bigger than that of the downstream slope. It can be deduced the lift force induced by negative pressure is the important breakage factor for dam abutment. It can be used to understand why the erosion on dam abutment is easily found happened in field tests. On the contrary, dam toe is also ruined easily by the large impact pressure (positive pressure). An important hint should be paid more attention. The shear stress is not the only important factor for erosion in dam breach formation. The erosion under the action of impact pressure and lift force deserve further research.