A low blow count during an SPT might suggest which of the following?

• A. A) Soil is fully consolidated
• B. B) Presence of soft clay
• C. C) Groundwater being lower than expected
• D. D) Density of sand is above normal

Answer: (C)

A low blow count during a Standard Penetration Test (SPT) typically indicates that the soil is likely to be softer or more fluid than denser materials. In the context of this question, if the groundwater level is lower than expected, it might result in lower effluent pressure above the soil, leading to a lower resistance to penetration. This can cause a lower blow count, suggesting that the soil is more saturated or potentially more compressible, which aligns with the observation of a low blow count.

When groundwater is at a lower depth than anticipated, soil layers that might otherwise be more compacted and stable when submerged may instead exhibit reduced resistance to penetration. Hence, interpreting a low blow count in terms of ground water conditions is a sound analysis for evaluating soil consistency and potential risks associated with construction projects in that area.

Other potential interpretations, such as fully consolidated soil or the presence of soft clay, might contribute to different blow counts but are not direct associations with the groundwater level. Generally, the concept hinges on understanding the complexities of soil mechanics and how groundwater influences soil behavior.