For the SPT test data you can use either deterministic or probabilistic methods for the liquefaction potential assessment. These methods are:
1. Eurocode 8
2. NCEER (1997)
3. Seed's deterministic method (2004)
4. Boulanger & Idriss deterministic method (2004)
5. Seed's probabilistic method (2004)
6. Liao et al. probabilistic (1998)
Fines correction method
Fines content influence SPT results. According to the liquefaction potential assessment method selected, different correcting methods are available.
SPT correction factors
In addition to fines content, several factors influence SPT results. These factors include overburden pressure (influence of depth), hammer energy ratio, borehole diameter, rod length and sampling method.
Subsoil class
This selection is enabled only if you have chosen the Eurocode 8 method. Eurocode 8 proposes a variation of the classic CSR equation in which includes the Soil Parameter factor S. The value of the Soil Parameter depends on the Subsoil class. The description of each subsoil class follows:
1. Subsoil class A
Stiff deposits of sand, gravel or over-consolidated clay, at least several tens of meters thick, characterized by a gradual increase of the mechanical properties with depth and by Vs values of at least 400 m/s at depth of 10 m.
2. Subsoil class B
Deep deposits of medium dense sand, gravel or medium stiff clays with thickness from several tens to many hundreds of meters, characterized by Vs values of at least 200 m/s at a depth of 10 meters, increasing at least 350 m/s at a depth of 50 m.
3. Subsoil class C
- Loose cohesionless soil deposits with or without some soft cohesive layers, characterized by Vs values below 200 m/s in the uppermost 20 m.
- Deposits with predominant soft-to-medium stiff cohesive soils, characterized by Vs values below 200 m/s in the uppermost 20 meters.
Round SPT
You can select a rounding method for the energy corrected and normalized SPT value. If your selection is None then the value of N1(60) will be a real decimal number. On the other two cases the value will be of integer type.