Soil Engineering and Foundation

Soil Engineering and Foundation ›› 2019, Vol. 33 ›› Issue (6): 668-673.

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Impact Analysis of Deep Foundation Excavations on Superstructure of Neighboring Buildings

To have a better understanding on impact of deep foundation excavation on the internal force and the gravity secondorder effect of the superstructure of adjacent buildings, the author developed an overall “pitsoilbuilding” numerical model with geotechnical finite element software PLAXIS88 to study the change rules of the total settlement, differential settlement and angles the of multistory framed buildings on the shallow strip foundation, the box foundation and the pile foundation respectively at different distances from the foundation excavations. Then, the rules of impact on the internal force and the gravity secondorder effect resulted from base displacement of the neighboring buildings caused by the foundation excavation was further studied through SAP2000 finite element method. The results show that the foundation excavation impacts the neighboring buildings on the box foundation heavier than it impacts those on the shallow strip and the pile foundations. This case study indicates that the impact of foundation excavation is generally and relatively small on multistory frames of the neighboring buildings. Specifically, the variations of the internal force of the multistory frame structures of the buildings on strip, pile or box foundation caused by the foundation excavation are all within 11%. When a building has more stories the gravity secondorder effect（PΔ）increases and 〖JP2〗the building of 12 stories has the largest PΔ effect (7.5%). Further, the impact is under control, for the bearing capacity of the building components can meet the requirement for a nearby foundation excavation according to calculation. However, with the increase of the number of stories, the PΔ effect of adjacent structures and the change trend of internal forces will increase. Therefore, for highrise or superhighrise buildings, special calculation and research are needed to determine the change of overall bearing capacity and effectively control the deformation of foundation pit according to the change of bearing capacity.   

  1. (China Railway First Group Co., Ltd., Xi’an 710054)
  • Received:2019-07-09 Revised:2019-07-31 Online:2019-12-28 Published:2019-12-28

Abstract: To have a better understanding on impact of deep foundation excavation on the internal force and the gravity secondorder effect of the superstructure of adjacent buildings, the author developed an overall “pitsoilbuilding” numerical model with geotechnical finite element software PLAXIS88 to study the change rules of the total settlement, differential settlement and angles the of multistory framed buildings on the shallow strip foundation, the box foundation and the pile foundation respectively at different distances from the foundation excavations. Then, the rules of impact on the internal force and the gravity secondorder effect resulted from base displacement of the neighboring buildings caused by the foundation excavation was further studied through SAP2000 finite element method. The results show that the foundation excavation impacts the neighboring buildings on the box foundation heavier than it impacts those on the shallow strip and the pile foundations. This case study indicates that the impact of foundation excavation is generally and relatively small on multistory frames of the neighboring buildings. Specifically, the variations of the internal force of the multistory frame structures of the buildings on strip, pile or box foundation caused by the foundation excavation are all within 11%. When a building has more stories the gravity secondorder effect（PΔ）increases and 〖JP2〗the building of 12 stories has the largest PΔ effect (7.5%). Further, the impact is under control, for the bearing capacity of the building components can meet the requirement for a nearby foundation excavation according to calculation. However, with the increase of the number of stories, the PΔ effect of adjacent structures and the change trend of internal forces will increase. Therefore, for highrise or superhighrise buildings, special calculation and research are needed to determine the change of overall bearing capacity and effectively control the deformation of foundation pit according to the change of bearing capacity.

Key words: Deep Foundation Excavations, Buildings, Finite Element Analysis, Structural Internal Force, Gravity Second-Order Rffect

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