Suggestion for Controlling the Implementation of Root Piles Partially Embedded in Bedrock-Paper

Paper

Pdf Summary

The paper proposes practical quality-control measures for root piles partially embedded in bedrock, based on 91 piles constructed in São Lourenço da Mata, Brazil. The site’s subsurface consists of weathered soil over granite bedrock, with four geotechnical regions showing differing rock conditions.<br /><br />A rockdrill is recommended for rapid, relatively low-cost checks of overburden elevations, bedrock continuity, and weaker layers. Its findings help define where competent rock begins and reduce the risk of piles having less rock embedment than specified. The authors also recommend adapting standard pile-monitoring records to document drilling time separately in soil and rock, alongside pile depths and other construction data.<br /><br />Construction should be supervised throughout. Key checks include casing depth, drilling progress and equipment condition, hole cleaning, reinforcement placement, grout injection pressure, and grout volume. Rock-drilling time can help assess whether the designed embedment was achieved, but must be interpreted in light of rock strength, operator experience, drilling tools, and compressor capacity. A poorly functioning hammer can create misleading noise and progress records, compromising estimates of embedment.<br /><br />Most of the 91 piles were drilled in under two hours. Approximately 70% achieved a rock-drilling rate equivalent to one metre in 20 minutes, with some variation. The authors suggest using region-specific average drilling times as a warning benchmark: unusually short times may indicate that the required length in competent rock was not achieved. Overall, combining rockdrill investigations with detailed, continuous construction monitoring can improve confidence in pile embedment and bearing capacity.

Keywords

root piles

quality control

bedrock embedment

rockdrill

grout injection

construction monitoring

pile drilling time

granite bedrock

geotechnical investigation

São Lourenço da Mata