Taking the Ji’nan rail transit line R1 in the Beijing-Shanghai high speed railway bridge with small radius of shield tunnel as the engineering background

we analyzed the impact of the shield tunnel process on the high speed railway bridge and combined with the construction conditions of straight line

polygonal-shape and curve three kinds of isolation pile layout

to investigate the deformation control effect.The results show that the stress state of the soil around the pile and bridge deformation characteristic curve caused by tunneling shield construction was more complex than straight shield

in the absence of isolation piles

piles settlement was more than1 mm and exceeded the design requirements of specification.The horizontal displacement of pile foundation was as high as 3.112 mm.For high speed railway bridge the deformation was too large.Comparative analysis of three kinds of isolated pile layout

straight line isolation pile can not guarantee the safety of high speed railway bridge

but curved and polygonal-shape pile isolation can effectively control the deformation of high speed railway bridge.Considering economy and ease of construction

we determined the optimal layout to be polygonal-shape pile.Study results have great guiding significance for small radius isolation shield tunnel support construction.