Analytical Study for Uncoordinated Deformation of Existing Pipeline and Soil Induced by Tunnel Undercrossing
To analyze the effect of a void under the existing pipeline on its deflection response during tunnel undercrossing construction,a theoretical model and an analytical solution of the uncoordinated deformation of the existing pipeline and soil induced by tunnel undercrossing construction were presented.Firstly,the existing pipeline was regarded as an Euler beam on a tensionless Pasternak foundation.According to the contacting condition of the pipeline and soil,the equations for the uncoordinated deformation control of the pipeline and soil caused by the tunnel undercrossing construction were established,and the corresponding formulas for the pipeline deflection were derived.Secondly,the influence of the parameters on the length of the void under the existing pipeline was discussed by using the proposed theoretical method,including the vertical soil pressure acting above the void,the flexural stiffness,and the width and maximum value of the formation settlement trough at the position where the existing pipeline located.Finally,a normalized empirical formula was proposed for calculating the length of the void under the existing pipeline induced by tunnel undercrossing construction,further simplifying the calculation method of existing pipeline deflection induced by the undercrossing construction of new tunnels.The research results show that the length of the void under the existing pipeline has a good correlation with the two normalized parameters(the ratio of the stiffness of the existing pipeline to the foundation,as well as the ratio of the vertical soil pressure acting above the void of the existing pipeline to the maximum value of the formation settlement trough),and the correlation coefficient between the calculated value of the fitting formula and the theoretical data is close to 1.
uncoordinated deformation of pipeline and soillength of voidPasternak foundationtunnel undercrossingtunnel deflection and track surface deformation
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