Abstract: According to the complicated structures of the city high-rise buildings and the difficulty of setting up instruments externally,this paper puts forward subregional regression model to determine building inclining state through fitting surface of foundation settlement.The monitoring points were equably distributed on the building foundation,whose settlement was measured periodically.Fitting each block of foundation settlement,the local deformation features were obtained.According to the features,the deformation regions were divided.Finally,the oblique angle and direction of buildings were calculated through the normal vector of fitting surface.Compared with traditional tilt observation methods,results show that subregional regression model can meet the actual engineering requirements and it has better precision and feasibility than regression plane model.

Key words: tilt observation, foundation settlement, regression plane model, subregional regression model