AIR AND WATER PERMEABILITY OF COMPACTED UNSATURATED COHESIVE SOIL

THE AIR AND WATER PERMEABILITIES OF UNSATURATED COHESIVE SOILS HAVE BEEN MEASURED IN A MODIFIED TRIAXIAL CELL PERMEAMETER, WHICH MAINTAINS SEPARATE CONTINUITY OF BOTH THE AIR AND WATER PHASES DURING PERMEATION. THREE DIFFFERENT COHESIVE SOILS HAVE BEEN TESTED AND THE RESULTS INTERPRETED IN TERMS OF THE CLUSTER CONCEPT OF SOIL STRUCTURE, WHICH RECOGNISES THE EXISTENCE OF BOTH MACRO- AND MICRO-PORES. BOTH AIR AND WATER PERMEABILITY ARE SHOWN TO BE DOMINATED BY THE GEOMETRY AND DEGREE OF SATURATION OF THE INTERCLUSTER MACRO-PORES. COMPRESSION OF THE SOIL ALWAYS REDUCES THE AIR PERMEABILITY BUT CAN INCREASE THE WATER PERMEABILITY BY INCREASING THE MEMBRANE FLOW AROUND THE CLUSTERS. THE RELATIONS BETWEEN SOIL SUCTION, OCCLUSION OF THE AIR CHANNELS, AND COMPACTION WATER CONTENT HAVE ALSO BEEN STUDIED. /TRRL/