These contour maps show the expected depths of freeze corresponding to the design Freezing Index (FI) for fine-grain soil (Figure 1) and coarse-grain soil (Figure 2). The fine-grain soil calculations assumed a density of 1600 kg/m3 (100 lb/ft3) and water content of 20 percent. The coarse-grain soil calculations assumed a density of 2080 kg/m3 (130 lb/ft3) and water content of 5 percent. Notice that frost depth is greater in coarse-grained soil.
Figure 1: Fine-Grain Soil Frost Depth (inches)
Figure 2: Coarse-Grain Soil Frost Depth (inches)