Natural soils are often structured due to the development of the resistance of soil structure during the depositional and the postdepositional processes. Current investigation on structured soils is generally focused on the mechanical behavior at the macrolevel. In this study, a natural strongly-structured diatom earth with high natural water content but high undrained shear strength is introduced. The mercury intrusion porosimetry (MIP) tests are performed on the strongly-structured diatom earth to investigate the evolution of the microstructure during consolidation.
     The change in the pore size distribution obtained by MIP under different stress levels due to consolidation indicates that the microstructure varies little at the stress level less than the consolidation yield stress, but changes significantly in the vicinity of the consolidation yield stress. The undisturbed natural diatom earth has two big peak differential pore size distributions.