Drilled deep foundations may be subjected to horizontal loads. Under this condition, the behavior analysis is complicated due to the tridimensionality of the problem. However, the models used in engineering practice often reduce the analysis to two dimensions. In this paper the procedure proposed by Matlock and Reese (1960) is modified for its applicability to loess soils. An alternative to establish the variation of the horizontal subgrade reaction module as a function of depth, for soils with intermediate characteristics between sands and clays, such as silty soils, is developed. An analogy between the cavity expansion and deflection of a pile subjected to lateral loads is established for construction of horizontal charge transfer p-y curves under natural humidity and saturated conditions. Finally, two study cases are analyzed, where the response of pile installed on loess silty soil layer suffering localized wetting is computationally evaluated. Results show the importance of considering the accidental wetting increase, when the piles are installed in unstable soils. [ABSTRACT FROM AUTHOR]