Numerical and experimental modeling of geomechanical behavior of partially saturated soils

The Barcelona Basic Model (BBM) has been implemented in a finite difference-based computer program to simulate the behavior of unsaturated soils subjected to wetting. The BBM implementation was verified using analytical solutions, and the proposed model has been used to simulate the response of a compacted embankment under complete saturation and suction induced conditions. Numerical analyses indicate that considerable amount of total and differential settlements could develop at the top surface of the embankment. BBM is executed into FLAC2D extending a defined module for modified Cam Clay (MCC) and has been set up an analytical solution for suction-dependent stress and strain. Evaluating the effect of anisotropy and nonlinear apparent tensile strength in unsaturated soils, a modification to BBM formulation has been proposed and optimized by developing numerical analyses to reduce the size of elastic region of loading collapse (LC) curve. Then, an experimental study in the literature is investigated by utilizing comparative curves from BBM and modified BBM indicating well agreement with natural circumstances. As a result of the work presented in this research, finite difference codes with BBM and modified BBM has the capability of simulating the real behavior and is operational being applied to problems associated with earthen structures in unsaturated or partially saturated of expansive soils as a three-phases medium.

Bearing Capacity Behavior of Skirted Foundations on Unsaturated Soils

One of the most important factors for designing a safe foundation is the amount of bearing soil capacity and allowable settlement according to the type of structure. Therefore, in geotechnical engineering, the aim is to improve foundations' bearing capacity in many ways, some of which are expensive, and the other section is difficult to implement in some sites. Skirted foundations consider as an ideal solution to improve cost-wise soil tolerance by reducing materials and installation time. At present, there are several applications, including offshore platforms, bridges, turbines, oil installations, and high-load facilities. This paper investigates the behavior of carrying capacity of skirted foundations through experimental models on the sand. To examine the effect of various saturation conditions, various ratios of length to width of the footing base at different relative densities and different conditions for saturations dry, saturated, and partially saturated soils are considered. It was found that the magnitude of soil bearing enhances with increasing ratios of length to the width of the base of the footings for all cases. The increase in performance ratio increased linearly to 1.5 in footing depth (D/B) and then decreased according to the test results after this point.