Small-Strain Shear Modulus

Small-Strain Shear Modulus 1 (Sands)

Small-Strain Shear Modulus 1 ($//<![CDATA[ \begin{array}{l}G_0\end{array} //]]>$) of sand in Small_Strain_Shear_Modulus_1 is defined as:

$$//<![CDATA[ \begin{array}{l}\displaystyle G_0=C_1 \cdot \left( \frac{q_c}{\sqrt{\sigma'_{v0}}}\right)^{C_2} \cdot q_c\end{array} //]]>$$

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

Where:
     $//<![CDATA[ \begin{array}{l}q_c\end{array} //]]>$, $//<![CDATA[ \begin{array}{l}\sigma'_{v0}\end{array} //]]>$ and $//<![CDATA[ \begin{array}{l}G_0\end{array} //]]>$ are in kPa.
     $//<![CDATA[ \begin{array}{l}C_1\end{array} //]]>$ is 1634 in the published formula, and is stored in the Small_Strain_Shear_Modulus_1_C1 field.
     $//<![CDATA[ \begin{array}{l}C_2\end{array} //]]>$ 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 $//<![CDATA[ \begin{array}{l}G_0\end{array} //]]>$ 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 ($//<![CDATA[ \begin{array}{l}G_0\end{array} //]]>$) in Small_Strain_Shear_Modulus_2 is defined as:

$$//<![CDATA[ \begin{array}{l}\displaystyle G_0= \frac{\gamma_{bulk}}{g} \cdot V_s^2\end{array} //]]>$$

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

Where:
     $//<![CDATA[ \begin{array}{l}V_s\end{array} //]]>$ is taken from the first of these fields with data: Shear_Wave_Velocity_Extrapolated or Shear_Wave_Velocity_1
     $//<![CDATA[ \begin{array}{l}\gamma_{bulk}\end{array} //]]>$ is taken from Bulk_Unit_Weight

This correlation of $//<![CDATA[ \begin{array}{l}G_0\end{array} //]]>$ is applicable to all soil types.