read this post here Push piers and helical piers are commonly used to level and stabilize foundations that have experienced movement. Although both types of piers can be used to lift foundations that have experienced settlement, only helical piers can withstand uplift forces which can occur in expansive soils. A detailed investigation of soil moisture conditions and expected changes in the future is required to determine the possibility of future uplift. If uplift is expected then helical piers are a better solution than push piers.
http://endsdhi.com/13614-dtf53001-rencontre-sexe-53.html Helfrich-Associates has investigated many properties to determine if the most suitable option is push piers or helical piers.