Settlement control by deep and mass soil mixing in clayey soil

Abstract

This paper discusses the influence of adding various amounts of cement to and changing the water content of clayey soil and their effects on controlling the settlement of a superstructure with various improvement area ratios (IARs). As a first step, the physical and mechanical properties of clayey soil from Bandar Imam Port, Iran, with 4, 6, 8 and 10% cement content and various water contents (30, 48 and 70%) were determined. Sample preparation was carried out using the wet deep soil mixing (DSM) method. The relationship between secant modulus at 50% strength (E50) and curing time for various cement contents was determined. In addition, different DSM column patterns with IARs of 0, 0·2, 0·3, 0·4 and 0·5, considering floating and end bearing DSM columns, were modelled using the finite-element method. Soil improvement by mass mixing of layers 2–7 m thick was also studied. The optimisation of various IARs and DSM characteristics and patterns enables production of a chart guide for preliminary design.