Small-Strain Shear Modulus

Small-Strain Shear Modulus 1 (Sands)

Small-Strain Shear Modulus 1 ( $\begin{array}{l}G_0\end{array}$ ) of sand in Small_Strain_Shear_Modulus_1 is defined as:

$\begin{array}{l}\displaystyle G_0=C_1 \cdot \left( \frac{q_c}{\sqrt{\sigma'_{v0}}}\right)^{C_2} \cdot q_c\end{array}$

Rix and Stokoe (1992), CPT in Geotechnical Practice p 94

Where:
$\begin{array}{l}q_c\end{array}$ , $\begin{array}{l}\sigma'_{v0}\end{array}$ and $\begin{array}{l}G_0\end{array}$ are in kPa.
$\begin{array}{l}C_1\end{array}$ is 1634 in the published formula, and is stored in the Small_Strain_Shear_Modulus_1_C1 field.
$\begin{array}{l}C_2\end{array}$ is -0.75 in the published formula, and is stored in the Small_Strain_Shear_Modulus_1_C2 field.

The constants are stored on CPT_POINT_CORRELATION_PARAMETERS and CPT_PROJECT_CORRELATION_PARAMETERS tables.

This correlation of $\begin{array}{l}G_0\end{array}$ is calculated only when the Soil_Type_1 field value on the CPT_DATA table is Coarse or Mixed for that row.

Small-Strain Shear Modulus 2

Small-Strain Shear Modulus 2 ( $\begin{array}{l}G_0\end{array}$ ) in Small_Strain_Shear_Modulus_2 is defined as:

$\begin{array}{l}\displaystyle G_0= \frac{\gamma_{bulk}}{g} \cdot V_s^2\end{array}$

Elastic theory, CPT in Geotechnical Practice p 74 and 94, NCHRP Synthesis 368 p 31

Where:
$\begin{array}{l}V_s\end{array}$ is taken from the first of these fields with data: Shear_Wave_Velocity_Extrapolated or Shear_Wave_Velocity_1
$\begin{array}{l}\gamma_{bulk}\end{array}$ is taken from Bulk_Unit_Weight

This correlation of $\begin{array}{l}G_0\end{array}$ is applicable to all soil types.

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