Study Of Influence Of Ground Subsidence On Behavior Of Existing Composite Foundation

With extensive applicability and good economy, composite foundation hasalready been used widely. In the using period of composite foundation for50years oreven longer time, the ground subsidence may occur induced by the groundwater levellowering or other reasons. When the existing composite foundation is in the areawhich ground subsides, it will be influenced by the ground subsidence in differentdegree. It has been reported that the safety of composite foundation cannot be ensuredeven after bearing test, leading to engineering accidents such as the destruction orfailure of the foundation in China due to ignoring the influence of ground subsidenceon the load-bearing capacity of existing composite foundation. Therefore, it hasfar-reaching reference value and realistic directive significance to further study theinfluence of ground subsidence on the behavior of existing composite foundation.Using previous research conclusions as references, the influence of thecharacteristics of existing composite foundation by ground subsidence induced by thegroundwater level lowering is preliminary studied by using model test, numericalsimulation and theoretical calculation methods. These researches may be providinghelpful reference conclusions for engineering design. The main research contents andresults of this paper include:(1) Based on Winkler elastic foundation model, considering ground subsidenceinduced by the groundwater level lowering, the successive approximation calculativemethod for bearing capacity and settlement of composite foundation is built. Thecalculation results are then compared with numerical simulation results. Thecalculation results are found to be in good agreement with the numerical simulationresults, which validating the accuracy of the developed calculation method.(2) Model test on behavior of3×3group piles composite foundation under upperload and ground subsidence induced by the groundwater level lowering is designed insand foundation. Combined with numerical simulation method, the settlement,pile-soil stress ratio, axial force, skin friction and neutral point of existing compositefoundation which influenced by ground subsidence are discussed. The results showthat, settlement of reinforced pile and foundation, pile-soil stress ratio and axial forcesin reinforced pile increase in evidence, and neutral point in pile moves down, thelength impacted by negative skin friction of upper part pile over neutral pointlengthens gradually, value of negative skin friction increases gradually along with ground subsidence increasing.