PREDICTION OF GROUND DEFORMATION INDUCED BY SHIELD TUNNELING CONSTRUCTION

Theoretical analysis shows that ground movement patterns induced by shield tunneling construction for different kinds of soils will be different.Assuming soil is undrained,the Verriujt′s formula is modified by N.Loganathan′s method.Based on uniform ground movement pattern of shield tunnel,two-dimensional analytical solution of soil deformation induced by shield tunneling construction is deduced;and the method is applied to different construction phases.As shown in analytical calculation,the predicted ground displacements are in good agreement with the measured values;and this method is applicable for the clayey soil from flow-plastic state to stiffness state.While Loganathan′s formula is only fitted for flow-plastic state clay,the predicted ground settlements for stiffness state clay are smaller than the measured values.The settlement of soil above tunnel by shield construction increases nonlinearly from ground surface down to deep;and it reaches the maximum value in the roof of tunnel;the closer the soil to tunnel is,the faster the settlement is.The horizontal displacement of the tunnel surrounding soil increases from ground surface down to deep;but it reaches the maximum value over the tunnel axial line and then gradually reduces to zero.The nearer the soil to tunnel is,the larger the horizontal displacement of soil is.