Reliability Analysis And Study Of Urban Water Network System

Urban water network system is one of the most important basic establishments in modern city, and its operational reliability is directly related to the normal life and the industrial activity of people. With the rapid development of modern Sci. & Tec. and the persistent increasing standard of people's living, the reliability of urban water network system has been the one of the research hotspots in recent years. Through reliability assessment of the water network, it is helpful to find out the weakness of the existed system, and then the corresponding maintenance and alteration can be easily carried out. It can be utilized to compare the different designs.Reliability analysis and study of the urban water network system has been carried out in this study, and the main work and conclusions are as follows: First of all, on the basis of the reliability of water network system, the corresponding research content has been confirmed, which includes the modeling and analysis of hydraulic conditions for water network, establishing the evaluative index of reliability, the study on the evaluative method of reliability for pump stations and the insuring measures of their normal operation, the reliability study on the water network and so on.There are many units in the pump station, and the influencing factors of equipment are more complex. Based on the reliability theory of reparable systems, the method of reliability units is applied to obtain some common unit analytical models of reliability, and then the reliability index of pump station has been achieved. The insuring measures for reliability of pump station have been put forward from the viewpoints of design, installation, operation and maintenance.The underlying assumption for the traditional models is that nodal demands are fixed and can be fully satisfied regardless of the pressure in the system. There are numerous occasions (i.e. emergence of magnitude accident and demands in excess of design capacity), if the demand outflow is still replaced by actual outflow for hydrodynamic calculation, this will lead the calculative results of network pressure to be unsatisfied. The hydraulic analysis in the state of malfunction is indispensable for the analysis of reliability of water network. Considering the dynamic variation of nodal overflow with the nodal pressure, the analytical model of pressures in water network has been established in this study. The feasibility of the method has been proved through the example.The contented degree of water network with the consumer's requirement for pressure and outflows is defined as the reliability. Because the nodal outflow is the function of the nodal pressure, both of them can be regarded as an index, and the contented degree of the nodal demand is utilized to assess the reliability of water network. Probability and hydraulic analysis are combined to establish evaluative models of nodal and systemic reliability of water network, respectively.