Lots of practical projects have revealed that the accurate calculation of lateral pressure at rest in the under-consolidation stratum plays a crucial role in the stability analysis and safety design. Therefore

this paper investigates the evolution of lateral pressure at rest during consolidation in detail by theoretical analysis and numerical simulation. The relationship between the lateral pressure at rest and the overconsolidation ratio (OCR) is established

and a new method for calculating the lateral pressure at rest in the under-consolidation stratum is proposed. A new concept of equivalent earth pressure coefficient at rest is introduced in consideration of OCR effects. The proposed method is validated by the results of numerical simulation and laboratory tests. Moreover

the proposed equivalent earth pressure coefficient achieves a unified method for calculating the lateral pressure at rest in the both under-consolidation and normal consolidation stratums. The results reveal that the lateral pressure at rest in the under-consolidation stratum decreases linearly with the increase of OCR

and such OCR effect becomes more obvious as the effective friction angle of soil increases. The results of this paper could technically support the calculation of earth pressure in the under-consolidation stratum.