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Field Borings and Cone Penetration Testing

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Presentation on theme: "Field Borings and Cone Penetration Testing"— Presentation transcript:

1 Field Borings and Cone Penetration Testing
Richard P. Ray, Ph.D., P.E. Civil and Environmental Engineering University of South Carolina


3 Drilling Program The purpose of the Drilling Program is to determine the: Thickness, Lateral Extent, and Physical Properties of Each Layer of Soil Presence, Depth and Pressure of Water in the Soil Coupled with the Topographic Survey, This provides a 3D view of the site and the soil underneath. If the Upper Soils are Weak, a Deep Foundation system must be developed. This investigation may also determine where to find suitable fill material from Borrow pits.

4 Site Investigation To Properly Characterize a Site requires:
Literature Investigation to Determine What Has Happened at the Site Before (Prior History) What Investigations have been Made Near the Site Geology, USDA Soil Profiles, Utility Crossings, etc. On Site Surveying, Borings and Drilling, Bag Samples, etc. Laboratory Testing for Soil Properties and Classification Produce a Report about the site for the Owner Maybe develop a Foundation Design, Retaining Structures, Embankments, Cuts and Fills

5 Borehole Drilling Drilling Rig
Continuous Hollow Stem Augers With Removable Drill Rod And Center Head

6 Samplers Split Spoon Sampler – Disturbed Samples Shelby Tube
– Undisturbed Samples

7 Borehole Logs









16 or CPTu . Three basic measurements qc, fs, u2.
Interpreting results • When pore pressure is collected, referred to as piezocone or CPTu . Three basic measurements qc, fs, u2. • qc is typically corrected for pore pressure effects (qt). • qt = qc + u2(1-a), where a is net area ratio of tip, ranges from 0.6 to 0.8 depending on probe design. • Normalization for overburden stress. Qt = (qt-σvo)/σ′vo Fr = 100%[fs/(qt-σvo)] Bq = (u2-u0)/(qt-σvo) = pore pressure parameter




20 Estimated parameters from standard CPTu
• Undrained shear strength, Su • Drained friction angle, phi • Stress History, OCR • Equivalent N60 • Coefficient of lateral earth stress, Ko • Total density, relative density and void ratio, ρ , DR, eo • Constrained modulus, M • Sensitivity, St • Fines Content • Additional parameters



23 Thank-you Questions?

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