Ground Improvement - Selected Tunisian Case Histories

Abstract

This paper presents a detailed analysis of three Tunisian ground improvement case histories. The first case focuses on the cause of disorders that seriously affected the stability of an oil tank, initially built on a superficial soft clay layer improved by sand piles. Due to the underestimated length of sand piles, the oil tank operations stopped after non-admissible consolidation differential settlement. Retrofit solution using micropiles’ reinforcement revealed quite satisfactory to restart the functioning of the oil tank after fifteen years. The second case deals with the reinforcement of compressible silt sand layer by floating stone columns to reduce the long-term differential settlement of a gas storage facility. Recorded measurements during the follow-up of stage construction of the storage facility permitted the assessment of numerical predictions of the settlement of reinforced soil. The third case studies the stability of access ramps of an interchange in Tunis Centre. Built numerical plan strain modelling helped for the prediction of the behaviour of embankment access on improved Tunis soft soil by geodrains. Based on recorded settlements and horizontal displacements, followed the validation of computed consolidation settlement. Adoption of suitable parameters of hardening and soft soil modelling of the behaviour of Tunis soft clay is discussed.