Based on the provided reference, the friction ratio for various types of sand typically falls within the range of 1.2% to 2.2%. Specifically, coarse sand with gravel through fine sand has a friction ratio between 1.2% and 1.6%, while silty sand ranges from 1.6% to 2.2%.
Understanding Friction Ratio in Soil
The friction ratio is a parameter commonly derived from Cone Penetration Testing (CPT). It is calculated as the ratio of the sleeve friction (fs) to the cone tip resistance (qc), usually expressed as a percentage (Fr = (fs / qc) * 100%). This ratio helps engineers and geologists classify soil types and assess their behavior and strength characteristics. Different soil types exhibit distinct friction ratio ranges due to variations in particle size, shape, interlocking, and cohesion.
Friction Ratio Ranges for Sand and Other Soils
The provided reference illustrates how the friction ratio varies across different soil types, typically increasing from granular soils like sand to cohesive soils like clay.
Here are the friction ratio ranges from the reference:
| Soil Type | Friction Ratio |
|---|---|
| Coarse sand with gravel through fine sand | 1.2% - 1.6% |
| Silty sand | 1.6% - 2.2% |
| Silty sandy clayey soils | 2.2% - 3.2% |
| Clay and Loam, and loam soils | 3.2% - 4.1% |
As shown in the table, sand, being primarily granular, exhibits lower friction ratios compared to silty or clayey soils which have more fines and cohesion. The specific range for sand depends on its composition, with silty sand having a slightly higher ratio than cleaner sand. These values are crucial in geotechnical investigations for accurately identifying subsurface layers and their engineering properties.
