Experimental Study On The Mechanical Behavior Of The Buried Pipe Network Under Uneven Settlement

Buried pipelines can save ground space,beautify the city and transport long distance conveniently,thus they are widely used in oil or gas transportation and municipal engineering.The safe and reliable operation is the main factor of national economic development.At present,pipeline damage due to earthquake will endanger people’s daily life.So,it is important to study the mechanical properties of buried pipeline.A test model of small buried infusion pipe network was designed,which was suitable for indoor experiment.Also the uneven settlement was simulated by loading equipment-MTS.Then,effects on mechanical response of buried pipe network were investigated,such as branch position of pipe network,internal pressure of pipe,loading frequency,and so on.By analyzing the experimental results of stain,deformation and displacement of pipe for these working conditions,some conclusions are obtained.When the pipe passes through the settlement area,the maximum stain of pipe is at the center of this area which is the most dangerous position.The strain of main pipe at branch position is larger,which is less than the maximum strain at the center of settlement zone only.Branch position is more dangerous too.The maximum strain of branch pipe is located near the downstream junction.For the general infusion pipe network,the stability of pipe network is proportional to its internal pressure,the greater the pressure inside the pipe network,the more stable the pipe network.Under the cyclic loading,pipe damage occurs during the soil moving up.The bigger the loading frequency is,the earlier the damage does happen,which is earlier than the site settlement induced by unidirectional loading.In the actual engineering,branch position of the pipe network should be set in the downstream fixed area as possible,and proper fluid pressure should be selected.Pipe at the branch position and the junction of two areas and the center of the settlement area should be strengthened for earthquake resistance,which increases the seismic performance of pipe network.