Underconsolidated soil is the soil that has not finishedconsolidation under its self-weight. At present

there are two types ofoverconsolidation ratio for underconsolidated soil in literature

i.e.

equalto 1 and less than 1 respectively

which may cause confusion or misusing problems.We have sorted out the relevant contents of overconsolidation ratio in thewidely used soil mechanics textbooks and found that there are two different definitionsfor overconsolidation ratio

where the different denominators result in thedifference of overconsolidation ratio for underconsolidated soil. Usingknowledge graph method

we comprehensively analyze the conceptual meaning

historical origin and practical applications for overconsolidation ratio and underconsolidated soil. Results show that degree ofconsolidation or consolidation state parameters can be used as substitution foroverconsolidation ratio while involved in the problems related tounderconsolidated soil. Overconsolidation ratio should be defined as the ratioof preconsolidation stress to existing effective stress (OCR = pc /p′0

pc is the effective consolidation pressure in theearly stage

p′0 is thevertical effective stress)

which is consistent with the influence mechanism ofstress history on soil behavior

as well as the historical origin meaning ofthe concept.