Study On Leakage Law And Control Countermeasure Of Bell Socket Joint Of Municipal Drainage Pipe

As an important infrastructure of the urban drainage system,municipal drainage pipes are of vital importance to ensure the safe and normal operation of the city.Municipal drainage pipes,in general,can be divided into three categories: sewage pipes,stormwater pipes,and combined rainwater sewage pipes.Over time,the structural and functional properties of underground drainage pipes are gradually deteriorating due to the combined effects of aging,physical and chemical influences.Among them,drainage pipeline joint leakage is particularly serious.Leakage of drainage pipeline joint not only affects drainage safety,reduces the influent water quality of wastewater plants,thus affecting the operating efficiency and treatment effect of wastewater plants,but also increases the cost of wastewater conveyance and treatment.It is very necessary to control it with suitable methods.In this paper,through self-developed drainage pipe joint leakage simulation device,we study pipe joint infiltration and joint exfiltration laws for both concrete and plastic pipes,and use different joint materials for filling to study the leakage control effect,and use characterization means for testing and analysis of some interface materials for pipes.The main research results of this paper are as follows.(1)For concrete pipeline socket joint,whether infiltration or exfiltration,without considering the influence of water quality factors,the length of time and the sequence of water level changes do not affect the leakage rate of the pipeline joint,the exfiltration leakage rate is greater than the infiltration rate,the relationship between the leakage rate of the pipeline-joint and the water level pressure is consistent with the Torricelli model.Among them,the leakage of ordinary cement mortar rigid joints is more serious.The initial leakage water level pressure was 0 m,the leakage rate was about 2.00 L·min-1 at 0.5 m water level,and the leakage rate exceeded 9.00 L·min-1 at 5.0 m water level pressure,reaching a maximum of 13.10 L·min-1.By reducing the water-cement ratio of cement mortar filler or adding admixtures(bentonite,silica powder,et al),the leakage rate of the rigid joint of the pipe could be significantly reduced.The leakage rate of the rigid joint can be significantly reduced by reducing the watercement ratio of cement mortar filler or adding the appropriate admixture(bentonite powder),and the initial leakage level pressure is raised to 3.0 m,and the leakage rate is only about 0.50 L·min-1 under 5.0 m water level pressure.When flexible joints such as rubber seals are used,mortar or sealant sealing is required,which has a better overall leakage prevention effect than cement mortar joints,but it should be ensured that the rubber seal can still fill the joint after being deformed by pressure.(2)For the plastic pipe socket joint,the relationship between the leakage rate of the pipe joint and the water level pressure is in line with the Darcy model.Leakage is more serious when there is no filling material.The leakage rate at 2.5 m water table pressure for infiltration and 2.0 m water table pressure for outflow exceeded 16.80 L·min-1.The rigid joint filled with adhesive was tested to significantly reduce the leakage rate of the pipe,and the maximum leakage rate was 1454.38 m L·min-1 measured by AD2 at 5.0 m water pressure for outflow.The overall seepage control effect is better with flexible material joints compared to rigid joints.