Assessment And Analysis Of The Risks In The Municipal Water Supply Pipeline Network

With the rapid development of urban construction, the scale of urban water supplynetworks is also expanding but accompanied by more and more risks in water supplysecurity. Risk analysis and assessment of urban water supply networks have been animportant research subject.The water supply network in City A is taken as a research object and the waterquality indicators on the dividing line are detected and analyzed in this thesis. In orderto understand comprehensively the causes and intrinsic problems of the pipe explosionin the current supply network, the records of the pipe explosion in City A of the year2010is used at the same time to conduct some collation, classification and analysis ofdifferent aspects. At the end, a reasonable assessment is made and preventive measuresare taken about the water quality and the phenomenon of pipe explosion. The mainresults of this study are as follows:1Risk assessment of the water quality and its control measures（1）At65%of the measurement points, the residual chloride cannot come up tothe quota. I is oberved that at three of the measurement points,the residual chloride islower than the quota. The maximum value of residual chloride at the Crossroads3onthe Taihua avenue is0.04mg/L. The dividing line of wate supply is a junction ofdifferent water qulities. Therefore, there will occur mutual complement of nutritioussubstances and bio-chemical reactions due to the difference of water quality,causingthe loss of residual chloride. Besides, the long stay of the hydraulic power is also an important cause of residual chloride to be on the low side in the pipeline network onthe dividing line.（2）At65%of the measurement points, there has occured such a phenomenon asthe turbidity did not exceed the quota. There are only five measuremnt points whosequota-hit ratio proportion was lower than80%. Among the five, the quota-hit ratioproportion of turbidity at the measurement point near the Fangbei crossroads on theChangle avenue east was63.3%. In addition, the maximum value of turbidity at twopoints were detected as three times higher than the standard. Therefore, there willoccur mutual complement of nutritious substances and bio-chemical reactions due tothe difference of water quality.On the dividing line of water supply, pipes stay in thestate of different water qualities and at different speeds of flow of water, so their wallsare easy to corrode. When the direction and speed of the flow of water change, thesediments and bio-membranes on the pipe walls are washed off, which is the principalcause of a rise of turbidity.（3）At35%of the measurement points there has occurred such a phenomenon asiron exceeded the quota. At the measurement point on the Zhuhong avenue, the highestvalue of the iron content was detected as0.5169mg/L. Except the measurement pointon the Hancheng north road where manganese has once exceeded the quota, themanganese content at the rest of the measurement points are lower than the nationalstandard. The pipes need to be washed, aging pipes replaced and the processingtechnology at the water stations improved at regular times. In this way, the quality ofdrinking water can be improved effecively.The pipes need to be washed, aging pipes replaced and the processing technologyat the water stations improved at regular times. In this way, the quality of drinkingwater can be improved effecively2Risk of the pipe explosion and corresponding control measuresFoundation settlement and tubular ageing are leading cause of pipeexplosion,accounting for80%of the total.The pipe explosion in southern suburbsclosely relates to ground fissure,and percentage of pipe explosion caused by groundfissure movements is75.9%.the main form of pipe explosion is leakage of pipeinterface or breakage. Try to avoid the use of gray-cast iron pipe and galvanized steel pipe. PE pipe andplastic composite pipe would be best used for small diameter.ductile iron pipe and steelpipe would be best used for those pipes whose diameter was greater than100mm. Atthe section where it is easy for the basement to settle, reinforceing measures, such asan addition of expansion pipes, ought to be taken. When the pipes that are easy to beaffected outside and corrode are being laid, special anti-corrosion measures should beadopted. At places where ground fracturing is very active, pipes should be laid incasing and at the joints, flexible connection should be adopted as much as possible.