Often, geotechnical designs fail to account for soil water content variations. Experimental results and essential theoretical equations of unsaturated soil mechanics were used to estimate soil settling due to increased groundwater levels. This study explored silty soil behavior during isotropic consolidation tests in saturated and unsaturated conditions and consolidated sample suction control under constant loading. Experimental data and a numerical method based on unsaturated soil mechanics and one-dimensional consolidation settlement computation were then utilized to determine how rising groundwater levels affected the settling of a foundation on soil under constant loads. The results showed that the soil settlement caused by this phenomenon is related to the initial compaction and consolidation characteristics of the soil in unsaturated conditions, volume change characteristics in the infiltration paths, the dimensions and intensity of foundation loading, the depth of the initial underground water level and the rising rate. Also, the results show that the amount of settlement caused by soil wetting is more dependent on the depth of the initial underground water level and its rate of rise than the dimensions and intensity of foundation loading, which of course, the complete occurrence of these settlements requires equilibrium in matric suctions after wetting of the soil mass. In the present study, for a square foundation with dimensions of 10 to 20 m with uniform loading on a silty soil mass, the primary underground water level is 25 m depth and rises 1 to 10 m, the settlement is 5.5 mm to 49.5 mm, respectively. This relatively simple method proposed in this research, based on Terzaghi consolidation theory, can be used with appropriate accuracy to estimate the settlement of surface foundations caused by rising water levels.

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