OasisLMS

Abstract:

The assumed advantages of Grouted Displacement Piles are increased shaft adhesion and frictional capacity compared to standard drilled shafts due to the lateral compression of the surrounding soil and roughness of grout column.   Compression tests of screw-in Grouted Displacement Piles were conducted in 2023 and 2024 at sites in Centralia, MO and Lakeville, MN to determine the adhesion and frictional capacities in both cohesive and non-cohesive soil conditions and compared to theoretical pile capacity.  Pile types consisted of both 8.63-inch diameter and 12.75-inch diameter grout columns.  A 4-inch nominal, 0.337 wall screw in pile shaft was utilized with soil displacement assemblies, centralizer plates, and two 16-inch diameter helical plates to create the 8.63-inch diameter grout column.   For the 12.75-inch diameter grout column, a 6-inch nominal, 0.280 wall shaft was utilized with soil displacement assemblies, centralizing couplings, and two 20-inch diameter helical plates.  At the Centralia, MO site, three 8.63-inch diameter piles and one 12.75-inch diameter pile were tested at varying installation depths and installation torques.  The Centralia, MO site consists of medium stiff to stiff clays.   Testing yielded adhesion values and overall pile capacity greater than theoretical values calculated.   At the Lakeville, MN site, two 8.63-inch diameter piles were installed to 12 feet and 16 feet embedment and compression tested.   The Lakeville, MN site consists of medium dense to dense granular material.   Once again, testing yielded values greater than the theoretical values for both frictional capacity and overall pile capacity.  The compression testing performed confirmed that screw-in Grouted Displacement Piles can increase the shaft adhesion and frictional capacity in either cohesive or non-cohesive soils.