Experimental Study on Compressive Bearing Capacity of Helical Steel Grounting Pipe Piles

Aiming at the problems for instability and durability of halical steel pipe piles in deep marine soft soil, a helical steel grouting pipe pile was proposed. A two-stage test was designed. In the first stage, different tested piles were used for pile-forming tests to verify the feasibility of pile-forming processes. The influence of sleeves and grouting methods on pile-forming quality was analyzed, and the pile type design and the pile-forming process were optimized. In the second stage, the influence of sleaves and grouting methods on the ultimate bearing capacity of helical steel grounting pipe piles was studied by the compressive bearing capacity tests of improved single piles. The curves of loads and settlement displacement at pile tops and the typical failure characteristics of piles were obtained, and the variation characteristics of pile-soil interaction for helical steel grounting pipe piles were analyzed. Finally, the experimental results were compared with the calculation results by Chance^@ Civil Construction: Technical Design Manual compiled by Hubbell Power Systems, Inc. and Micropile Design and Construction Reference Manual issued by Federal Highway Administration of America. The test results showed that the helical paddles expanded the diameters of cemented grouting slurry and sleeves could effectively enhance the stability of piles. The grouting effect was significant and the full-section rotary jet grouting method could significantly increase the bearing capacity of piles under vertical compression.