Demo:
Input Parameters
Input Guidelines
The AASHTO 1993 correlation \( M_R = 1500 \times CBR \) is generally valid only for fine-grained soils with a CBR below about 10%.
For higher CBR values the MEPDG relationship \( M_R = 2555 \times CBR^{0.64} \) is often more appropriate.
Correlated Parameters
Equivalent CBR (USACE)
-
Resilient Modulus, MR (AASHTO 1993)
Imperial- psi
Metric- MPa
Resilient Modulus, MR (MEPDG)
Imperial- psi
Metric- MPa
Modulus of Subgrade Reaction, k
Imperial- pci (psi/in)
Metric- MPa/m
Step-by-step calculation
Formulation
DCP to CBR (USACE, Webster et al. 1992): \( CBR = 292 / DPI^{1.12} \), with DPI in mm/blow.Resilient modulus, AASHTO 1993: \( M_R\,(\text{psi}) = 1500 \times CBR \) (Heukelom & Klomp, 1962).
Resilient modulus, MEPDG (NCHRP 1-37A): \( M_R\,(\text{psi}) = 2555 \times CBR^{0.64} \).
Modulus of subgrade reaction, AASHTO 1993: \( k\,(\text{pci}) = M_R\,(\text{psi}) / 19.4 \). Conversions: 1 psi = 0.00689476 MPa, 1 pci = 0.271447 MPa/m.
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