The Influence Of Building Reservoir At The Down-Dream Of Culvert

As one of the water conservancy facilities, reservoir plays an important role in irrigation, flood control, power generation and river management. Water resource is lack in our country, because the problem of flood control in big rivers has not been solved completely and the speed of water use is increasing in both industry and city. And as a clean and non-polluting resource, water power is prior to other kind of power in most industrial countries as well as our country. In our country, rural area occupies a lot of areas where the water use relies mainly on water from reservoir. Thus, reservoirs are constructed in many places in our country.To construct reservoir at the downstream of existing culvert may influence the discharge capacity of the existing culvert. After the construction of the reservoir, the outlet water level of the culvert, which is in the backwater region of the reservoir, may be raised. Consequently, the water state in the culvert may be changed. Once the discharge capacity decreased, the flow which can be discharged reduced either. This results in drainage hindrance and submerging of the upstream district, as well as the subgrade soaking for a long time. After long time immersion, the bearing capacity of the subgrade will decease and the subgrade will collapse. This will lead to severe consequence.The culvert now is designed according to the culvert typical design. But in the making of the culvert typical design, there is a surplus value for the culvert discharge capacity. As the discharge capacity in the culvert typical design is not continuous, in order to guarantee the safety of the culvert, if the designed discharge capacity is between the two discharge capacities adjacent to each other in the culvert typical design, the culvert scale of the bigger discharge capacity is adopted. Thus, as long as the outlet water level of the existing culvert rises in a limit value, the discharge capacity of the culvert will not be influenced greatly. Only to determine the limited raising value, suitable advice can be given to the reservoir built at the downstream of the culvert.Three-dimensional model is built in this paper by the software FLUENT to make the numerical simulation of the culvert flow. Through the computation, influence to the culvert flowing state of the culvert downstream water level rising is analyzed and the limited raising value of the outlet of the existing culvert is determined.