This tool estimates the unit weight of soil from N SPT number based on available literature correlations and tables. The unit weight of soil, also known as bulk density, is defined as the weight per unit volume of soil. It represents the average weight of soil particles, including solids and voids, within a given volume. The unit weight of soil is expressed in terms of mass per unit volume. It can vary depending on several factors, including the type of soil, its gradation, moisture content, compaction, and the presence of organic matter or other constituents.

The current tool estimates the deformation modulus or modulus of elasticity of soft rock based on Hoobs (1974) mass factor theoretical equation. It requires as an input the unconfined compressive strength of rock from UCS laboratory tests and RQD values from coring. The equation also requires an estimate of the modulus ratio value, Mr, to account for rock type.

Based on RQD, the equation calculates the mass factor j, to account for rock mass discontinuities, fractures, and weathering and the modulus ratio value, M, to account for rock type.