Monopile foundations are usually used to support structures, such as electrical tower, foundations for low-rise building on weak soil and wind tower foundations. These structures are usually subjected to lateral cyclic loads generated by earthquakes, winds and waves. In order to support these loads, the design engineer usually chooses either to increase the pile diameter, pile length or both. However, these solutions increase the price of the project. Another solution, which is more economical, can be adopted. This second alternative consists of reinforcing the adjacent soil of the pile with stone columns. In order to evaluate the effect of stone columns on the behavior of a monopile under lateral cyclic loads, we performed a numerical Plane Strain model using the finite element software PLAXIS 2D in conjunction with the constitutive model “Hardening Soil model with small strain stiffness (HSS)”. The constitutive model was first calibrated and validated using measured data from centrifuge tests on a monopile in Fontainebleau sand. In the second part, a series of analyses were then carried out where cyclic lateral loads were applied to the pile for investigating the length and the diameter of stone columns.