Design and Construction Recommendations for Driven Piles in Intermediate Geomaterials-PPT Presentation

PPT Presentation

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The presentation develops design and construction recommendations for steel driven piles in intermediate geomaterials (IGMs), materials between soil and hard rock whose strength and variability make conventional pile design uncertain.<br /><br />It proposes classifying IGMs as soil-based or rock-based, with additional categories for fine- and coarse-grained materials and for shale weathering. Classification draws on field and laboratory indicators such as SPT resistance, unconfined compressive strength, rock-quality designation, and modified rock-mass ratings. The recommendations are supported by a database of pile load tests, including tests in shales and other geomaterials.<br /><br />For each IGM category, the research provides proposed static-analysis methods to estimate shaft and toe resistance, applicable ranges, and LRFD resistance factors calibrated using reliability analyses. Factors vary by material, resistance component, and target reliability; generally, greater uncertainty is reflected in lower resistance factors.<br /><br />The presentation also recommends adapting WEAP (wave equation analysis of piles) procedures for construction-stage capacity assessment. Five subsurface-condition scenarios account for different combinations of overburden soils and IGMs. Recommended inputs include material-specific quake and damping parameters, with alternatives using standard WEAP settings or parameters back-calculated from test data.<br /><br />The proposed implementation process is to improve site investigation, classify the geomaterials, use established methods for overburden soils and the new methods for IGMs, estimate pile resistance and depth using appropriate LRFD factors, and control construction through WEAP analysis, dynamic testing, and pile restrikes. Together, these measures aim to make pile design in IGMs more consistent, reliable, and economically informed.

Keywords

steel driven piles

intermediate geomaterials

pile design

shaft resistance

toe resistance

LRFD resistance factors

static analysis

WEAP analysis

pile load tests

geotechnical classification