Which soil type is best for dam embankment shells?

Which soil type is best for dam embankment shells?

• A. GW
• B. SM
• C. SP
• D. GQ

Answer: (D)

The outer shell of an earth dam needs a material that forms a durable, stable face, resists erosion, and can be compacted effectively to support the structure. Gravel that is well graded and quartz-rich provides dense packing, good interlock between particles, and long-term durability, which helps the shell resist seepage forces and erosion at the face. This combination makes gravel with quartz (GQ) the best choice for dam embankment shells. In comparison, other granular options may be less stable or more prone to erosion, so they don’t offer the same level of reliability for the shell.

The outer shell of an earth dam needs a material that forms a durable, stable face, resists erosion, and can be compacted effectively to support the structure. Gravel that is well graded and quartz-rich provides dense packing, good interlock between particles, and long-term durability, which helps the shell resist seepage forces and erosion at the face. This combination makes gravel with quartz (GQ) the best choice for dam embankment shells. In comparison, other granular options may be less stable or more prone to erosion, so they don’t offer the same level of reliability for the shell.