Piping is one of the main failure mechanisms that can affect the safety of water-retaining structures. A phenomenon that can occur when a local disruption of water structure caused sand erosion and concentration of seepage flow at that location. This entails sufficient hydraulic gradient resulting in the formation of shallow pipes in the sand layer. There are number of methods to increase the factor of safety against piping. An effective technique is soil reinforcement. The soil reinforcement can be performed by the inclusion of elements (strips, bars, etc) within the mass of soil in a preferred direction. Geogrids can be used as a convenient reinforcement material for improving the behaviour of the soil because of the high tensile resistance and significant friction in the soil. This paper presents laboratory experiments that were performed on unreinforced and reinforced soil samples. Reinforcement was done using different types of geogrid in different layers of the soil sample to investigate the effect of this method and arrangement of the geogrid sheets on the critical hydraulic gradient and resistance against piping. Subsequently, the results demonstrate that reinforcement increased the critical hydraulic gradient up to 75% compared to the value in unreinforced soil. The amount of improvement of the critical gradient is dependent on the arrangement and type of the geogrid
