Study of time-space united calculating method of stratum deformation caused by shield tunnel excavation

Based on the two hypotheses:(1) the force on shield working force is round and well-distribution;(2) the frictional force between the out surface of shield and surrounding soil is also well-distribution;the mechanical calculation model of shield is established by using the classical elastic theory of Mindlin. In this model,the changeable location of shield is considered when shield is working. Then the stratum deformation calculating formulas around tunnel caused by the additional force on the shield working force and the frictional force between the out surface of shield and surrounding soil are deduced. According to the stochastic medium theory,the stratum deformation caused by the loss of stratum which resulted from shield tunnel construction is deduced,in which the time-space effect of stratum deformation caused by tunnel construction is considered. A case of history is calculated and the time-space change rules of stratum deformation are studied finally.