Numerical investigation on ground and structure response of ancient site in complex strata caused by groundwater fluctuation and rainfall

As more and more ancient sites are discovered around the world, protecting them in situ has become a challenge due to issues such as ground settlement and masonry wall leaks caused by groundwater fluctuation or rainfall. In this study, laboratory tests, borehole tests and field high-density resistivity detections are conducted to obtain information for numerical modelling, including design parameters. A complex three-dimensional hydrological–mechanical coupling model is then established to investigate ground settlement and wall deformation caused by groundwater fluctuation and rainfall. The seepage simulation results for the initial state are accurately verified by high-density resistivity imaging. Both measured data and numerical results indicate that changes in a single water head point mainly result in wall settlement. The pattern of wall deformation changes from settlement to lateral deformation with an increase in the drawdown rate of groundwater level. Furthermore, delayed rainfall and high-intensity rainfall can increase foundation settlement and wall deformation. Settlement deformation determines the upper limit of the global deformation when wall nodes are mainly affected. In contrast, if lateral spreading dominates wall deformation, it determines the lower limit of the global deformation. This study provides reference for in situ protection and foundation reinforcement of ancient sites.