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The groundwater level (GWL) is a significant foundation design factor that often fluctuates with seasonal variations, causing a reduction in the strength and stiffness of submerged soil mass and resulting in an additional settlement that affects the structural performance of foundations. Pore water pressure (PWP) changes with the water level, and the excess pore water pressure (EPWP) changes during the loading stages. The pore water pressure (PWP) and excess pore water pressure (EPWP) variations were studied under full saturation with relative density (Dr: 50%, 75%, and 95%) and fluctuating groundwater levels, monitored through two piezometer sensors placed at 1B and 2B below the base of foundation (where the B=width of foundation). The experiments included loading rectangular and square footings on top of poorly graded sand. The results in full saturation indicated that the increase in the relative density of the sand only slightly increased the amount of PWP generations, though with a more noticeable impact on the EPWP with the time required for the EPWP to reach its maximum value range between 3 to 10 minutes in the majority of the results. In the fluctuating groundwater levels, the decrease in the water table below the base of the footings decreased the amount of pressure. [ABSTRACT FROM AUTHOR]

This research focuses on investigating the bearing capacity and settlement of dry sandy soil by the use of physical modelling tests involving the loading of the surface of the foundation on the dry sand with various relative densities (Dr=50, 75, 95). The results indicated that increasing the relative density multiplies the obtained bearing capacities. In general, the load-settlement curves showed non-linear behaviour for the sand, indicating that the settlement of the footing increased with increasing the applied loading until failure occurred. Increasing the relative density from 50% to 75% and from 75% to 95% increased the bearing capacity by about 50% in each case. For the failure mechanism of both footings with dense and very dense sand, general shear failure with total rupture of the soil was observed, and a local shear failure was observed for the sand with medium relative density. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of two parallel foundations resting on the cohesionless soil for different foundations. As there are many empirical and analytical studies of shallow contiguous foundations on the sand in various conditions, dimensions, and forms; where The attempts to investigate the behavior of soils under stress from two close foundations can be traced back to [1], six decades ago but there are very few studies on the effect of deep foundations on adjacent shallow foundations, and this is what the researcher will address. The impact of interference on tilt, settlement, differential settlement, total normal stress, and pressure are studied using the finite element PLAXIS 3D-2021[2]. The sand is stimulated using the Mohr-Coulomb soil model[3]. A parametric study is performed for different clear spacing between the foundations' S' is varied from 0B to 5B until effects end in numerical studies. It also presents the impact of the Variation length of piles on the interface. Observe the reduction of the effects of neighboring high buildings due to using piles, where the differential settlement and tilt were reduced by about 32.5% and 47.5% when using piles of lengths 9 m and 15 m, respectively, with comparing with the raft foundation in the distance 0B between the two foundations with a load of 12.5 KN/m² for old building and load of 200 KN/m² for a new building. [ABSTRACT FROM AUTHOR]

This study is concerned with the behavior of two convergent foundations resting on clay using three-dimensional plane strain finite element analysis. A Mohr-coulomb soil model was used to simulate soils using PLAXIS 3D V21, a finite element analysis software that perfectly simulates linear and plastic elastic behavior. The soil zone is divided into 10-node triangular points approach for calculating the mesh generation, with locally refined mesh near the foundations and very fine mesh near the domain boundaries. Differences in spacing between two foundations and new foundation depth are used to investigate their effects on settlement and tilt, the effect use skirted foundation as a new foundation. It was observed through numerical analysis that the interference affects the functions of the existing foundation and that the settlement and tilt decrease as the spacing between the two foundations increases. Also, increasing the depth of the new foundation leads to a decrease in the settling of the foundation and tilt. Also using a skirted foundation as a new foundation contributed in decrease risks of additional settlement and risk of tilt of existing foundation. [ABSTRACT FROM AUTHOR]