An Analysis Method For Settlement Of Existing Building Foundation Due To Decline Of Groundwater Level

Natural factors and engineering drainage often make the groundwater level of existing building falling, thus it will make another settlemen t or uneven settlement of the foundation of existing building, so the security of existing building is under threat and it has been a problem which can not be ignored. In order to evaluate the influence engineering construction on the security of existing building, it is necessary to discuss the analysis method for settlement of existing building foundation due to decline of groundwater level.Firstly, according to the Terzaghi principle about effective stress, an analysis method for the additional stress caused by the decline of groundwater level is developed with consideration of the engineering properties of settlement of existing building foundation due to the decline of groundwater level.Secondly, considering the characteristics of porous media of foundation soils and starting from the analysis of the macroscopic and microscopic stresses or strains, the change laws of mechanical deformation parameters of foundation soils under the action of stresses are obtained, thus the variation relationships of mechanical deformation parameters of existing building foundation soils under the initial or additional stresses due to the decline of groundwater level are established. These can fully reflect the incompatibility between macroscopic and microscopic deformation of particle skeleton for foundation soils.And then, on this basis, introducing the idea for layer-wise summation and step-loading, a new nonlinear analysis method for the settlement of existing building foundation due to the decline of groundwater leve l is put forward. It can reflect the impact of not only different depths or changes of initial stresses but also changes of additional stress due to the decline of groundwater level on mechanical deformation parameters of foundation soils.Finally, through the analysis of engineering examples with the calculated settlements by the existing similar method and the proposed method in this paper, which are compared with actually measured settlements, it is indicated that the suggested model and method in this paper is reasonable and feasible.