Normally consolidated Soil:
“If the initial vertical effective stress is approximately equals to the preconsolidation stress then this condition is known as Normally consolidated.”
“The soil whose present effective overburden pressure is the maximum pressure that the soil was subjected to in the past.“
In real world these two values are subjected to error due to sample disturbance and other factors. That is why the values obtained are rarely equal even if the soil is truly normally consolidated. In order to avoid misclassifying of soil, we will consider that the soil is normally consolidated if initial vertical effective stress and preconsolidation stress are equal within about 20 percent.