Abstract: Underpinning is a new concept summed up from engineering practice in recent years; its principle is based on the relative position(distance) between the excavation and the existing buildings, the weight of buildings, soil engineering property, the probable destroy type and extension, with the load transfer and the stress transfer theory as the guiding ideology; designing to use less underpinning component to attain the purpose of anti-lean. The finite element analysis software package, Plaxis ver7.2, is used to study the underpinning excavation engineering. The anchor dead pressure piles are used to underpin the existing structure; and the finite element simulation is used to study the effect of underpinning on the force and deformation of the bracing structure. Through finite element analysis, it can be found that the distance between the excavation and the existing buildings and the thickness of the weak layer are important factor to underpinning.

Key words: underpinning, excavation, anchor, dead pressure pile, bracing