Affect of mechanical properties changes of injecting cement paste on ground settlement with shield driven method

When using shield driven method to construct tunnels, mechanical properties of injecting cement paste will change at curing age. And then ground settlement will also change because of changes of mechanical properties of injecting cement paste. Based on the first line of Ningbo rail transit, this paper will discuss the effect of ground settlement caused by changes of elastic modulus and Poisson´s ratio of injecting cement paste using finite element simulation (FEM) software. The results show that ground settlement will increase if considering changes of elastic modulus, while ground settlement will decrease if considering changes of Poisson´s ratio. If changes of elastic modulus and Poisson´s ratio are both considered, we will accurately predict ground settlement .The results also show that elastic modulus and Poisson´s ratio at early stage of curing age play an important part in ground settlement prediction.