When considering the passive resistance of a closely spaced group of piles in cohesive soil, the total resistance cannot be calculated as the value of Eq. 6.29 times the number of piles. The reasons are because of the overlapping of passive soil wedges, soil gap formation, and creep of clay around the pile (long-term condition). As previously mentioned, shadowing is the process where the passive soil wedge in the trailing row of piles overlaps into the leading row of piles, resulting in a reduction of passive resistance.