Research On Influence Of Heritage Building Induced By Underpass Excavation

Pile foundation underpinning is often used in the excavation below the important existing construction. It is very effective to protect the historical building in especial. Because of the complexity of pile foundation underpinning and the significance of the historical building, it is very important to search the influence of the excavation of the subway tunnel on the superstructure.First, based on the theory and calculation method of pile foundation underpinning, the author used the ANSYS software to model the east station under the background of the Shenyang station tunnel project which both has the protected superstructure and the underground passage. And the author did the numerical analysis the structure response of Overall longitudinal tilting, the overall lateral tilt and 'pot' settlement. The checking calculation of the internal force and deformation in the normal service condition educe the stress state and deformation regularity under the three settlement forms. The result of the research proves:the main force of frame columns is axial force, and the side column's axial force is much larger than inner column's axial force; the main force of frame beam are shear and bending moment, and the force of the second layer beam is 15% larger than the first layer. Longitudinal settlement have more effect on the crossbeam, the horizontal settlement have more effect on longitudinal beam, and the 'pot' settlement have both effect on the longitudinal beam and the cross beam. Under the longitudinal and horizontal settlement, the deformation of the beam and column are linear whereas the 'pot' form is nonlinear.At the same time, the research prove that the ultimate settlement difference of the structure is related to the intercolumniation which has a approximate direct proportion relationship with the former. The final result proves that the ultimate settlement difference of the horizontal, longitudinal and 'pot' are 118mm,69mm and 23.5mm respectively, all of which are compressive failure.In addition, the change regulation of structure settlement can be obtained from the analysis of settlement data which proves that it is available and reasonable to use the pile foundation to protect the historical building in the tunnel excavation. The settlement of stage ? (original surface and column cap removing), stage ? (east foundation pit excavation), stage ?(mining method under the station), stage IV(cut pile) is about 35%,30%,25% and 10% of the total settlement respectively. The disturb of the original surface and column cap removing is the largest. After the passage structure closed loop, the disturb of pile cutting is not much.In the end, the internal force changing regulation of each construction stage can be obtained from the internal force analysis based on the measured data of east station frame construction, and we can do the assessment of the safety of the structure in the construction. The calculation result proves that each construction stage satisfy the specification requirements, the position of largest force is at the largest settlement column and whose corresponding frame beam. In the four stages of construction, the amplification of the axis force of the column is the 8.2%,17.7%,38.9% and 52.8% respectively; the shear of the beam is 1.6,3.6,6.9 and 9 times respectively of the gravity; bending moment is 1.5,4.2,6.6 and 9.8 times respectively of the gravity.