Liquefaction Input Data

The Input Data is specified in the Liquefaction Options dialog. As the data is entered, a graph of the data (displayed on the right side of the dialog) is updated.

Liquefaction input data can be imported (see the Importing Liquefaction Input Data topic) and exported, or copied from Excel and pasted into the dialog.

For all input types, you also have the choice of entering custom Fines Content (%) values, although this is not required. If a custom Fines Content is not specified, the default value of 15% is used for all depths.

Standard Penetration Test (SPT)

To carry out a liquefaction analysis with SPT data, N values must be specified. The SPT N value, or blow count, is a sampling method which indicates a soil's compressive strength. The N value for a soil is lower for soft soil and increases with increasing soil stiffness or strength.

There are a number of correction factors that can be applied to N values (energy ratio, borehole diameter, etc.). See the Depth Correction topic for more details. The corrected N values (N₆₀ values) are graphed alongside the input N values in the Data tab of the liquefaction graphs window.

For other scaling factors and correction factors that can be applied to SPT values, see the SPT Advanced Options topic.

The analysis methods that are available for analyses carried out using SPT data are outlined in the SPT Analysis Methods topic.

Cone Penetration Test (CPT)

The data entered for a CPT analysis is q_c and f_s.

q_c is the tip resistance (tip force divided by the cross-sectional area of penetrometer)

f_s is the sleeve friction (sleeve drag force divided by the sleeve surface area)

Based on q_c and f_s the normalized cone tip resistance, Q, and the friction ratio, F, are calculated. From these two values, the soil behaviour type index, I_c, is determined. In the Depth Correction tab of the Liquefaction Options dialog, you can specify a threshold I_c value.

For a list of other scaling factors that can be applied when CPT input data is used, see the CPT Advanced Options topic.

The analysis methods that are available for analyses carried out using CPT data are outlined in the CPT Analysis Methods topic.

Shear Wave Velocity

The input data required is V_s. There are no depth correction factors for V_s.

For a list of other scaling factors that can be applied when VST input data is used, see the VST Advanced Options topic.

The analysis methods that are available for analyses carried out using VST data are outlined in the VST Analysis Methods topic.