This standard specifies field and laboratory methods for determining the dynamic properties of soil, such as shear modulus, Young's modulus, damping ratio, and Poisson's ratio. These properties are critical for the analysis and design of structures subjected to dynamic or seismic loads, particularly machine foundations.
Determination of dynamic properties of soil - Method of test
Quick Reference Values
Typical strain for wave propagation tests< 10^-4 % (low-strain)
Typical strain for block vibration tests10^-4 % to 10^-2 % (medium-strain)
Typical frequency range for block vibration test oscillators5 to 60 Hz
Minimum size of concrete block for block vibration test1.5m x 0.75m x 0.7m
Key Formulas
G = ρ * Vs^2 — Shear modulus from shear wave velocity
Cu = (4 * π² * fnz² * m) / A — Coefficient of elastic uniform compression from block vibration test
E = 2G * (1 + μ) — Young's modulus from Shear Modulus and Poisson's ratio
Practical Notes
The choice of test method depends on the applicable strain level of the design problem; wave propagation tests for low-strain (seismic analysis) and block vibration or cyclic tests for medium to high-strain (machine foundations).
Proper seating of test equipment (base plates, geophones) is crucial for accurate results. A thin layer of plaster of paris or grout is often used to ensure good contact.
This code provides the test *procedure*, not design values. The results are highly site-specific and must be interpreted by a qualified geotechnical engineer.