Which site class classification is assigned to very dense soil or soft rock?

The classification of very dense soil or soft rock aligns with Site Class C according to the standards typically outlined in seismic design codes like the International Building Code (IBC) and other geological assessment frameworks. Site Class C is defined as "stiff soil," which includes very dense sands, gravels, and soft rock types that have a minimum shear wave velocity typically ranging from 180 to 360 m/s (approximately 590 to 1180 ft/s).

This classification is crucial in geotechnical engineering and seismic design, as it influences how structures are designed to withstand seismic forces. Denser soils and soft rocks have a higher capacity to dissipate seismic energy compared to softer, more compressible soils, affecting the anticipated ground motion response during an earthquake.

In contrast, Site Class A refers to hard rock with very high shear wave velocities, while Site Class B represents intermediate soils, and Site Class D typically signifies soft soils that may have detrimental effects in seismic situations. Thus, recognizing that Site Class C directly represents the characteristics of very dense soil or soft rock solidifies its classification as the correct answer.