GEOLOGICAL AND ENGINEERING CHARACTERISTICS OF EXPANSIVE SOILS AND ROCKS IN NORTHERN OMAN

The geology and former climate of northern Oman favoured the formation of smectite clay minerals in certain materials which are implicated i n ground heave problems. Investigations have shown that the smectite c ontent of these expansive materials was developed in Oligocene, Miocen e and Pliocene times. No evidence of a significant content of smectite was found in pre Eocene strata or in Quaternary strata, except for De sert Fill. It is shown that the main types of expansive materials in n orthern Oman are bentonitic mudstones, marls and silty mudstones, argi llaceous dolomitic limestone, altered conglomerates and the desert fil l derived from these. These swelling materials exist as impersistent b ands within the bedrock Tertiary conglomerates and limestones. A geote chnical testing program was carried out on undisturbed samples from Su ltan Qaboos University staff housing areas where building damage had o ccurred, to evaluate mineralogical composition, cation content and swe lling characteristics. The test results characterized these soils/rock s as highly expansive type with Na-smectite as the dominant clay miner al. (C) 1998 Elsevier Science B.V. All rights reserved.