# Spatial Evolution Analysis of Tailings Flow from Tailings Dam Failure Based on MacCormack-TVD
## 4 Tailings Industrial Area Slope Maps and Dam Failure Simulation Conditions
### Initial Conditions of the Model  
Several conditions of the dam failure simulation are as follows: (1) set the tailings pond as a flood overtopping dam failure, and the tailings dam instantaneously breaks at the beginning of the simulation; (2) the maximum value of the Manning's coefficient of the zone is 0.25, and the minimum value is 0; (3) the initial dam material properties are much larger than the tailings material, and the occurrence of the initial dam is not taken into consideration regarding a breach (4) initial and boundary conditions (dam height, breach morphology, etc.) are set; (5) tailings material is set to be a homogeneous fluid. The breach flow is an important factor affecting the downstream risk, but there are many factors affecting the breach flow, so it is difficult to accurately predict the maximum breach flow. Due to the catastrophic and unacceptable nature of dam breaching accidents, in order to fully analyze and assess the downstream impacts of dam breaching accidents, combining the breach flow of the physical modeling experiments with the results of numerical simulation estimation, the maximum breach flow of tailings is set to 136.41 \(\times\) 104 m\({}^{3}\). Under the condition of the maximum breach flow rate, the dam breach simulation was carried out, the satellite cloud map of the topography of the tailings pond and the distribution of the downstream residential area is shown in Figure 8, and the modeling preprocessing was carried out by using arcgis. The project area topography modeling is shown in Figure 9.  
Figure 8: Satellite cloud map of tailings ponds. According to the analysis, the maximum inundation depth of most tailings ponds is about 0-40 m, the flow depth in the exit area of the ditch as well as in the low depression of the river is more than 40 m, the final flow depth of the ditch is about 0.5 m, the furthest distance of the north-south tailings flow transport is about 834 m, the furthest distance of the east-west tailings flow is about 650 m, and the tailings are mainly piled up in the open land which is 300-800 m away from the tailings ponds. The tailing sand mainly accumulates in the open area 300-800 m away from the tailing pond. Due to the height difference between the upper and lower part of the trench, the flow velocity at the narrow downstream position of the trench is the largest, with a maximum velocity of 2.5 m/s, and most of the flow velocity at other positions is 0.25 m/s. The maximum impact value is at the downstream position of the trench, and after the tailings flow enters into the downstream open area from the trench, the impact force decreases rapidly, and the impact force ranges from 20 to 500 KN/m. The tailings pond is mainly located at the downstream position of the trench. At the downstream of the tailing pond, there are mainly the secondary well and its ancillary equipment, the field office, and accommodation building, and there is also a private house next to the office building. According to the characteristics of the tailing flow damage, combined with the analysis parameters such as the maximum flow depth and flow rate, the degree of risk of disaster and the maximum inundation range of the tailing flow, etc. are obtained. Referring to the research results of Prof. [PERSON] of Central South University and related literature, the following disaster risk classification criteria (Table 4) are used to classify the disaster degree risk level of the project [29]. Figure 11: Maximum flow depth cloud map. After the calculation and analysis, the disaster risk classification map after dam failure was obtained, as shown in Figure 12. From the analysis results in Figure 12, it can be seen that the main affected area is the downstream processing plant area, the impact area is distributed in the shape of a fan, and the settlement area in the downstream of the tailing pond in the mining area; the 700,000-ton resource utilization project is not affected, and the downstream residents are affected to a certain extent, which is a low-disaster area.