N-SPT values observed during testing are not utilized directly in the assessment of soil properties. These values need to be corrected to account for hammer efficiency , borehole diameter,sampling method, rod length and the overburden pressure. Current tool sets the rules to allow the calculations for the correct SPT numbers, N60 and (N1)60.

One of the most important soil aggregate properties is relative density.
The relative density of soil is used to describe the state of compactness of granular material and is generally qualitatively described as very loose, loose, medium dense, dense, and very dense. The currenttool uses N SPT number and theoretical correlations to define relative density of soil.

Friction angle together with cohesion defines the shear strength parameters of soil. Its definition is derived from the Mohr-Coulomb failure criterion. It can be determined in the laboratory by direct shear test or triaxial tests or from theoretical correlations with density or N SPT number.

The current tool sets the rules to calculate friction angle for granular soils based on N SPT number.

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.

This current tool estimates the modulus of elasticity or Young's modulus of soil based on theoretical correlations with N SPT number. Correlations available on this tool are mainly based on recommendations from the Foundation Analysis and Design book from Bowles (5th Edition, 1997). The tool also allows for estimating Young's modulus as an average value from multiple correlations (ie. selecting correlations for gravelly sand and saturated sand and averaging between the two).

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.

The current tool is an implementation of Casagrande’s plasticity chart (1948). It is used to classify fine-grained soils using their plasticity characteristics as expressed by the Plasticity Index (IP) and Liquid Limit (LL).

Samples with high plasticity tend to be clay-based materials, samples with low plasticity tend to be silt-based materials, and samples with no plasticity tend to have little or no silt or clay.

Lateral earth pressure is the pressure that soil exerts in horizontal direction. It affects the design of retaining walls, basements, tunnels and deep foundations. Current tool estimates the earth pressure at rest, active and passive earth pressure coefficient based on Jaky's formula and Rankine Earth Pressure Theory.