Astm D4633

ASTM D4633 focuses heavily on the measurement of Shear Wave velocity ($V_s$) because it is the most reliable indicator of soil stiffness for engineering purposes. By measuring the time it takes for a generated wave to travel from the surface to a sensor deep underground, engineers can calculate these velocities with high precision.

| Term | Meaning | |------|---------| | | The percentage of theoretical hammer energy actually delivered to the rods. Typical SPT hammers range from 40% to 80%. | | EF (Energy Efficiency) | Often used interchangeably with ETR, but can refer to efficiency relative to a reference energy (e.g., 60%). | | Theoretical Energy | Hammer weight × drop height (e.g., 140 lb × 30 in = 4,200 in-lb). | | Measured Energy | The actual energy recorded by the sensors during a blow. | astm d4633