Experimental Study On The Influence Of Leakage Of Pressurized Pipeline On Surrounding Medium

The urban water supply system is the infrastructure to maintain urban operation.Due to many factors such as aging of pipes and corrosion of pipes,the loss of water supply pipe network seems unavoidable.Therefore,a series of problems such as economic losses and waste of water resources will affect the normal operation of the economy and society.After the pipeline leaked,the erosion of the soil by the pressurized water flow will cause erosion of the surrounding soil,the structural damage of the pipeline,causing a major safety accident such as bursting and road collapse.Therefore,paying attention to the interaction between water and soil after leakage of water supply pipe network is of great significance for controlling leakage loss and reducing road surface collapse accidents.Current scholars always use numerical simulations or small-scale experimental devices to study the interaction between water and soil in pipe network leakage.In this paper,the experimental device is designed to simulate the buried depth closer to the real overburden,and the whole process of fluidization is studied by controlling the flow observation.The experiment simulates different buried depths by changing the upper sand bed,and simulates different leakage areas by replacing the pipeline.In addition,the geotextile is introduced to study its role in controlling fluidization and reducing leakage.In terms of fluidization phenomenon,this paper records the erosion of sand bed during the process of flow change.It is found that in the three fluidization stages proposed by the scholars,the fluidized hole stage can be divided into two stages.The phase of the slow fluidization and the phase of the rapid fluidization are manifested by the difference in the growth rate of the fluidized pores.In the calculation of head loss,the pressure sensor is installed on the wall of the experimental device and the leakage pipe to record the excess pore water pressure and the pressure change in the leakage pipe under different flow rates during the fluidization process.In addition,through the trend of total head loss,the loss of seepage head in the sand bed at the same height is larger than that in the fluidized hole,and the calculation method of head loss in the sand bed under two-dimensional leakage is given.It is found that the head loss in the fluidized hole is approximately proportional to the 0.2 power of the fluidized hole height.In this paper,the geotextile permeability,the laying distance from the leakage opening and the thickness of the sand above the geotextile are set as variables to study the role of geotextile.In controlling the fluidization phenomenon,the critical flow rate of fluidization will increase correspondingly after laying the geotextile,but the complete fluidization critical flow rate will not be affected.In the fluidized hole stage,the geotextile can effectively slow down the growth of the fluidized hole.The closer the leakage distance is to be better,the permeability of the geotextile and the thickness of the upper sand bed seems not important.In the aspect of using geotextiles to reduce the amount of leakage,the calculation method of head loss at geotextiles is mainly studied.Through the analysis of the pressure inside the pipe,it can be found that the head loss of the geotextile is proportional to the flow rate,inversely proportional to the permeability of the geotextile,and related to the laying height of the geotextile.At last the article gives the Corresponding fitting calculation formula about head loss at geotextile.