Helical Piles - Geotechnical behavior in MO residual soils-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines the geotechnical behavior of helical piles in the clay and alluvial silt soils of Chesterfield Valley, Missouri. Its goals were to assess installation-torque data, compare predicted and tested pile capacity, evaluate the in-situ torque factor (Kt), and consider how load testing can improve design and manage uncertainty.<br /><br />The initial design used a working load of 28.2 kips, an estimated installation torque of 9,464 lb-ft, and Kt = 7. A test pile with 10-, 12-, and 14-inch helices was installed and tested under static axial compression in accordance with ASTM D1143, using the quick-test procedure. The measured installation torque was 8,100 lb-ft.<br /><br />The pile’s performance exceeded the expectations of the preliminary analysis. At the 28-kip working load, deflection was about 0.215 inches. Capacity estimates based on different interpretation methods ranged from approximately 42,000 to 87,000 pounds; the reported ultimate soil capacity was about 84,500 pounds, while the structural limit was 89,000 pounds.<br /><br />The authors conclude that properly designed and installed helical piles can provide strong load-bearing performance. Preconstruction load tests help verify design assumptions, confirm foundation behavior, and support safe optimization of safety factors. Installation anomalies should be monitored and assessed, and calculation-software inputs should be calibrated to local conditions.

Keywords

helical piles

geotechnical behavior

Chesterfield Valley

clay soils

alluvial silt

installation torque

torque factor Kt

static axial compression

load testing

pile capacity