In Robertson e Wride, the correction to the cone resistance due to the content of fine material is determined by the following procedure:
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where Kc depends on the fine content, FC (%):
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FC (%) is calculated using the following formula:
The liquefaction resistance for a magnitude equal to 7,5 (CRR7,5) is calculated as:
if (qc1N)cs < 50
if 50 ≤ (qc1N)cs < 160
CSR is calculated using the formula mentioned in the Introduction chapter of this Guide, for different magnitude must be inserted the corrective factor MSF (Magnitude Scaling Factor) as recommended by NCEER (see Table 1 - Seed Idriss method).
To determine the values of the reduction factor rd are used the formulas recommended by an expert group of NCEE (National Center for Earthquake Engineering Research):
if z < 9,15 m:
if 9,15 ≤ z < 23 m:
where z is the depth in meters
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