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This study evaluates a binary mixture of fly ash and lime as a stabilizer for natural soils. A comparative analysis was performed on the effect on the bearing capacity of silty, sandy and clayey soils after the addition of lime and ordinary Portland cement as conventional stabilizers, and a non-conventional product of a binary mixture of fly ash and Ca(OH)2 called FLM. Laboratory tests were carried out to evaluate the effect of additions on the bearing capacity of stabilized soils by unconfined compressive strength (UCS). In addition, a mineralogical analysis to validate the presence of cementitious phases due to chemical reactions with FLM was performed. The highest UCS values were found in the soils that required the highest water demand for compaction. Thus, the silty soil added with FLM reached 10 MPa after 28 days of curing, which was in agreement with the analysis of the FLM pastes, where soil moistures higher than 20% showed the best mechanical characteristics. Furthermore, a 120 m long track was built with stabilized soil to evaluate its structural behavior for 10 months. An increase of 200% in the resilient modulus of the FLM-stabilized soils was identified, and a decrease of up to 50% in the roughness index of the FLM, lime (L) and Ordinary Portland Cement (OPC)-stabilized soils compared to the soil without addition, resulting in more functional surfaces. [ABSTRACT FROM AUTHOR]

In recent years, the use of helical piles as a deep foundation option for structures has increased dramatically because they offer definite advantages over other solutions. The present study undertook a comprehensive investigation of the axial compressive behavior of helical piles in both sandy and clayey types of soil using finite element (FE) modeling. Since the helices of helical piles are more likely to disturb the soil adjacent to the pile, first some approaches are proposed to consider the effect of soil disturbance during a helical pile installation in numerical models. The numerical models have been validated and calibrated through full-scale compressive loading results using the ABAQUS software. The validated numerical models were used to investigate the load transfer mechanism of a typical helical pile in different types of sandy and clayey soil, and the numerically obtained ultimate bearing capacities were compared with the theoretical ones. Based on the comparison, it was found that the theoretical procedure overpredicts the ultimate capacity of helical piles in medium and dense sand. Additionally, different geometrical aspects of a typical helical pile were investigated using FE modeling in order to employ perfect geometry for studying the compressive behavior of a helical pile group with a square grid arrangement. The results revealed that the shape of the block failure mechanism in clayey soil differs from that in sandy soil. The acquired shapes are used to suggest a theoretical method for calculating the ultimate bearing capacity of a helical pile group based on the block failure mechanism. [ABSTRACT FROM AUTHOR]