Quantitative research on the development difference of scaling off on the sunward side and nightside of earthen sites

•The development difference of scaling off on the sunward side and nightside of earthen sites was revealed.•The new indicators of salt migration gradient (SMG) and normalized shrinkage rate (NSR) were proposed.•The mechanism of salt difference and heterogeneous shrinkage on different building orientations were indicated.•Environmental monitoring was comprehensively analysed to explain the development difference of scaling off on different building orientations.