Evaluation of consolidation and permeability parameters for Neogene green clay from Belchatow Sebastian Kowalczyk Warsaw University, Faculty of Geology, Poland ABSTRACT: The article presents and discusses the reasons for variability of consolidation obtained in consolidometric tests with continuous loading on samples of green clay from “Belchatow” mine. The obtained values of the filtration coefficient in CL tests are closely related to the consolidation coefficient and they have a wide range of variability. Correct assessment of the reasons for variability of consolidation parameters may enable effective determination of low- permeable soil filtration coefficient in the consolidation tests conducted under continuous loading. Assessment of cohesive soil filtration properties, especially in the case of clays, is a complex issue. It is caused by specifics of the filtration process in low-permeable soils, as well as the Reed to adept testing procedures to these conditions. In order to determine consolidation and filtration parameters in cohesive soils with permeability coefficient lower than 10 -5 m/s tests with variable hydraulic gradient are generally applied. Among them there are indirect methods based on Terzaghi’s consolidation theory and assumption of the two-phase medium can be distinguished. Such tests are conducted among others in consolidometers and the results of permeability coefficient obtained in such tests significantly differ from the ones obtained using other laboratory methods, which causes them to be assessed as estimations (Krogulec, 1994; Żak i Ossowski, 1996; Kaczyński i in. 1997, 2000, Dobak, 2007). Determination of soil permeability using the consolidometric method depends on generation of a continuous increase of pore water pressure during the test. The character of pore water pressure increase depends on the loading speed and changes of the soil structure caused by the loading. Therefore in order to correctly determine filtration parameters mainly a reliable measurement of pore water pressure is required. Consolidation tests have been made using the system of continuous loading (CL consolidation) on clay samples with intact structure taken from clay and sand complex in three areas of the Coal Mine „Belchatow” from the „Belchatow Field”. Parameters of