The maximum value of effective stress in the past divided by the present value, is defined as over consolidation ratio (OCR). The O.C.R. of an over consolidated clay is

ANS:C - more than 1

Over-consolidation ratio (OCR)= (Maximum applied effective stress in past )/(Maximum applied effective stress in present).

For overconsolidated soil OCR > 1.
For Normally consolidated soil OCR = 1.
For Under consolidated soil OCR < 1. Because effective stress increases with time due to continuous consolidation, so the present value of effective stress is more and the OCR will be less than 1. Over-consolidation ratio (OCR)= (Maximum applied effective stress in past )/(Maximum applied effective stress in present).

For overconsolidated soil OCR > 1.
For Normally consolidated soil OCR = 1.
For Under consolidated soil OCR < 1. Consolidation mostly happens in clayey soils only. Initially, there will be pore water pressure, after consolidation is said to be happened; pore water escapes and thus plastic readjustment of clay particles occurs, results in very low effective stress. Thus the ratio will be greater than 1 always.