With the rapid development of subway network

the situation where shield tunnel going across the adjacent tunnels are becoming more and more common. But the research on the interaction between shield tunneling and nearby tunnels is still under perfection. On the background of Shanghai’s typical soft layers

method of centrifuge modelling is adopted to study the effects of above-crossing construction of shield tunnel on existing tunnels and nearby strata at different grouting ratios. The in-flight tunneling simulation techniques are used in centrifuge model tests to simulate the construction of shield tunnel

where discharge or injection of heavy fluid is adopted to simulate the excavation unloading

ground loss and grouting successfully. The existing tunnels’ behaviour and the ground response in terms of settlement

pore pressure and internal forces during and after the construction period at different grouting ratios are analyzed. Results show that the existing tunnel structure would undergo heave during the above-cross of a new tunneling; while grouting can alleviate the heave. However

excessive grouting ratio during construction would disturb the surrounding ground and cause more settlement in the long run after the construction.