Theory And Experimental Study On Blockage Recognition Of Drainage Pipeline In Utility Tunnel

Under the background of vigorous development of comprehensive pipeline corridor,it is required that rainwater and sewage pipelines should be incorporated into comprehensive pipeline corridor reasonably according to local conditions in the area where comprehensive pipeline corridor is constructed.The Gallery entry of drainage pipeline can effectively monitor the state of pipeline such as leakage and deformation in real time,so as to improve the service life of pipeline.With the help of comprehensive Gallery information management platform,intelligent water service platform can be built,and scientific and humane management and control can be achieved.Operating faults of transmission and distribution pipelines mainly include pipeline breakage,leakage,blockage,etc.There are few studies on blockage faults of drainage pipelines.With the vigorous promotion of intelligent city and intelligent pipeline gallery,strengthening the research of drainage pipeline fault identification can provide certain basis for production managers to take corresponding emergency and early warning measures,and through technical means to identify the fault location and judge the fault degree.Under different design conditions of gravity flow and pressure flow,when the drainage pipe is incompletely blocked or completely blocked,the changes of fluid pressure and liquid level parameters in the drainage pipe provide experimental basis for identifying the blockage fault of the drainage pipe in the comprehensive pipeline gallery.According to the characteristics of fluid flow in the pipeline,a flow physical model was established.FLUENT simulated the conditions of incomplete blockage length and height change in corridor drainage pipeline.Single factor variable comparison was carried out under the conditions of complete blockage,and the variation law under different conditions was explored.Based on the principle of similarity criterion,a laboratory test device is established,and the test conditions are determined according to different working conditions of the test model.By comparing and analyzing the changes of parameters obtained from the software simulation,the basic basis for identifying the drainage blockage fault of the comprehensive pipeline gallery is obtained.The results show that the blockage of gravity flow drainage pipeline in comprehensive pipeline Gallery reduces the flow area of the pipeline,produces backwater phenomenon upstream,and the upstream water level continues to increase,overflows from the top of the blockage position,and forms weir flow,where the water flow falls,forms a jet,the water depth decreases,and the flow velocity increases.The height of gravity flow pipeline changes before and after different blockage degree.When the flow rate is constant,the overflow width of weir top reaches the maximum when the cross-section area is circular and the blockage degree is 50%,and the head on weir is the smallest.The larger the flow rate,the more obvious the change trend of the graph is.The influence of gradient on the water-passing capacity of the blocking position of the drainage pipeline in the comprehensive pipe gallery is that with the increase of blocking strength from 0.2 to 0.8,the water-passing loss is 40.4%,46.5%,51.0% and 53.6%,respectively.The water-passing capacity decreases with the increase of blocking strength.Under the same blocking strength,the longer the blocking length,the greater the overflow loss.When the blocking strength is 0.2,the slope increases from 0.003 to 0.006 in turn.Compared with the blocking length of 0.5 m,the overflow loss increases by 8.3%,12.6%,17.3% and 21.8% under the condition of blocking length of 2 m,respectively.The overflow loss increases with the increase of the slope condition.The loss flow rate is inversely proportional to the roughness coefficient of the pipe wall.The larger the roughness coefficient of the pipe wall is,the larger the loss flow rate is at the blocking position.The sudden change of the influence of pressure flow drainage pipe blockage on pipeline pressure exists within a few meters after the blockage position along the pipeline flow direction.The sudden drop at the blockage point is due to the sudden increase of local resistance at the blockage point,which results in the sudden decrease of pipeline pressure,and then the trend of pipeline pressure drop tends to ease.The overall distribution of pressure along the length of the pipe is that the pressure at the front end of the pipe is greater than that of the normal pipe.The blockage results in pressure choking in the front position and pressure loss after blockage.Before and after the blockage point,the fluid pressure experienced a sharp drop to a sharp rise in the direction of flow along the pipeline.The greater the degree of blockage,the greater the change of flow parameters before and after the blockage point.