CPT Indexing of In Situ OCR in Clays

by Paul W. Mayne, Law Engineering Testing Co, Washington, DC, USA,

Document Type: Proceeding Paper

Part of: Use of In Situ Tests in Geotechnical Engineering


Cone penetration tests may be used to index the in situ preconsolidation pressure in clay deposits. A specified relationship between C//u/ sigma //vo and the overconsolidation ratio (OCR) may be used to theoretically calculate sigma '//vmax from CPT data. Alternatively, a review of cone data from 42 different sites indicates that general statistical trends occur between laboratory determined sigma '//vmax and the measured cone resistance and between OCR and the net cone resistance. Site specific calibration of the cone with oedometer tests is recommended. Based on limited data from 11 sites tested by piezocones, the excess pore pressure measured during cone penetration provides an independent evaluation of the in situ OCR.

Subject Headings: Penetration tests | Conical bodies | Field tests | Clays | Load and resistance factor design | Soil analysis | Soil pressure | Pore pressure

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