Abstract:Aiming at the low efficiency of traditional blocking technology and the inability to clear silt simultaneously, an integrated construction technology of airbag blocking and dredging is proposed to solve the problems of high dynamic drainage, silting and waterlogging in the reconstruction of urban pipe network. Through the scaling model test, the deformation characteristics and failure mechanism of the airbag under water pressure gradient are studied. Combined with the distribution characteristics of pipeline sediment, the dynamic control model of the internal pressure of the airbag is established. The results show that when the internal pressure of the airbag is equal to the full pipe flow pressure after deducting the sediment thickness, the blocking can be effectively achieved. When the upper water level exceeds the limit, the bottom discharge is triggered to avoid waterlogging. At the later stage of construction, the water is pressurized and the airbag is released. The dredging is achieved by hydraulic scouring, with a dredging rate of over 90%. After the application of this technology in Guangzhou Village-in-City Pipeline Network Reconstruction Project, the single-point blocking efficiency can be increased by 40%, the construction cost reduced by 32%, the construction period shortened by 30%, and the hydraulic scouring instead of mechanical dredging can reduce energy consumption by 65%. The research confirms that the precise control of the internal pressure of the airbag is the core of the integration of blocking, pressure relief and dredging, which provides an efficient and low-carbon innovative solution for the reconstruction of urban drainage system.
