What is the common borehole test that measures the density of granular soils and the consistency of certain clays?

The Standard Penetration Test (SPT) is a widely used method in geotechnical engineering to assess the properties of granular soils and certain types of clays. During this test, a split-barrel sampler is driven into the ground at the bottom of a borehole using a hammer. The number of blows required to drive the sampler a specified distance, typically 12 inches, is recorded. This blow count is related to the density of granular soils and the consistency of clays.

The SPT results can help determine the soil's relative density, which is critical for understanding its bearing capacity and behavior under load. This makes the SPT a fundamental tool for engineers when designing foundations and other structures. The test is also relatively quick and cost-effective, allowing for extensive data collection during initial site investigations.

While other methods like the Dynamic Cone Penetrometer or the California Bearing Ratio test exist, they serve different purposes or are suited for specific soil conditions. The Compaction Test is focused on assessing soil compaction rather than providing a direct measurement of soil density or consistency in situ. Thus, the Standard Penetration Test is the most common borehole test for these soil characteristics.