Soil Profiles

Soil profiles are vertical columns through the ground which are separated into levels of strata. A new table is created for each soil profile.

Layers must be entered in order of decreasing level.

The lateral extent of each soil profile is specified later as a soil zone.

Definition

Name

The name is a convenient way of identifying a particular soil profile.

Levels

The levels are defined in terms of the level at top of each stratum and the number of intermediate displacement levels.

Displacement levels sub-divide each layer of soil into a number of sub-layers. For example the specification of two intermediate displacement levels will divide the layer of soil into three sub-layers.

This also defines the number of stress calculation points, with depth, for the Boussinesq solution. The stresses are calculated at the centre of each sub-layer.

Soil Material Properties

The basic soil properties are the Young’s modulus & Poisson’s ratio. Where nonlinear behaviour is required a nonlinear soil curve can be assigned to individual layers of strata.

The pile-soil interaction property allows the selection of a pile-soil interaction property to be associated with each layer of a soil profile.

Notes

The number of displacement levels calculated is determined as the larger of:

• a user-specified number ($N$) given for each soil layer
• a generated number ($n$) taken from the Maximum Allowable Ratio ($R_a$) between values of Young’s modulus ($E$).

The value of $n$ is calculated by

$$n = \frac{log(E_b/E_t)}{log R_a}$$

So for the example illustrated above, if $R_a = 1.5$

$$n= \frac{log(70/20)}{log1.5} = 3.089 \rightarrow 3$$

The value of $n$ is always taken as the next lowest integer.

The value of $R_a = 1.5$ is normally sufficiently accurate for most problems.