Calculation Method of Disturbed Settlement of Buried Structures Considering Side Wall Friction

In addition to the lower foundationsupport,the large volume buried structure bears significant friction effect due to the large-area contact between the side wall and the soil,the additional structural displacement caused by which needs to be focused on.Taking the settlement of the stratum and its internal structures induced by external construction disturbances as the research object,the further effect of side wall friction on the structure settlement was investigated with consideration of the buried structure subsidence with the underlying stratum,and more accurate vertical disturbance displacement calculation results were obtained according to the characteristics of large-volume buried structures.With the typical engineering case of the shield tunnel excavation underpassing the underground passageway,the mechanical equilibrium equation of the passageway structure affected by the excavation disturbance was established based on the Pasternak foundation model and the two-stage analysis method.Then,the Clough-Duncan hyperbolic model was introduced between the side wall of the structure and the soil,and the load balance formula under the vertical friction between the structure and the stratum was further established to describe the additional effect of friction on the passageway settlement.The equation was iteratively solved by the finite difference method.Finally,the applicability of the calculation method was verified by practical engineering.The results show that the excavation disturbance of shield tunnel brings different settlement between the buried structure and the surrounding stratum,and the resulting settlement difference between the passageway and the side soil generates significant shear stress in the side wall of the structure.The large contact area between the passageway side wall and the soil makes the structure continue to sink with the stratum,and the settlement calculation result corresponding to the friction in the soft soil stratum increases by more than 30%.Therefore,the additional vertical displacement caused by side wall friction cannot be ignored in large-volume buried structures.