ASTM D1586 Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils

ASTM D1586 sets up a standardized procedure for conducting the test in soil borings with the use of a split-barrel sampler, which is actuated through a drop hammer. The standard penetration test is perhaps the most popular in-situ geotechnical testing method. It generates both qualitative and quantitative data by integrating both blow count measurements with maximum disturbed soil sample retrievals. The straightforward nature, flexibility, and historical data record, along with the aids linked to SPT, qualify it as a beneficial instrument used in exploratory site testing, bearing capacity assessments, and the determination of any alterations in subsurface conditions.

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• It gives the disturbed soil samples to be visually classified and tested in the laboratory.
• It applies to granular and cohesive soils that are found during geotechnical research.
• It assists in foundation design, earthwork analysis, and characterization of the site.

Applications of ASTM D1586

• Superficial and deep foundation design.
•  Bearing capacity of soil.
• Potential assessment of liquefaction of seismic areas.
• Estimation of the settlement of structures.

ASTM D1586 Common Challenges and Troubleshooting

Inaccuracy in SPT is affected by the rod length, efficiency of hammer energy, and the agitation in the boreholes or imbalanced driving. Corrections usually result in standardization of the results (e.g., overburden pressure or energy ratio). The reliability of the data is increased through the consistency in the level hammer drop height, clean equipment, and straight boreholes. And it is also good practice to standardize the transfer of energy using automatic hammers.

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Low N-values usually show loose sands and soft clays, whereas high N-values are evidence of dense sands, stiff clays, or hard soils. Empirical correlations are used by engineers to approximate parameters like relative density, shear strength, and bearing capacity. Modifications to overburden pressure and energy efficiency of the hammer can be used to get the corrected N-values to use in the design.

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