Physical modelling of lime stabilisation in soft soils around deep excavations

Abstract

The availability of space above ground decreases as cities expand, causing a demand for very deep underground structures so developments must mitigate the risk of damaging adjacent buildings. This is especially critical in soft clays where ground movements are considerable and can extend far beyond the excavation site. This paper investigates the efficacy of a shallow lime stabilised clay layer on reducing heave and the settlement profile behind an embedded retaining wall. Centrifuge modelling at 160g was used to observe surface and subsurface soil movements of a 12m deep excavation (H) supported by a retaining wall of 8.8m embedment at prototype scale. Since this research focussed on measures used to minimise heave the model comprised a high stiffness, fully supported 'rigid wall' to eliminate ground movements attributed to wall deformation. A direct comparison between a reference test, with no improvements and a test comprising H/2 thick 5% lime stabilised layer indicated that the lime treatment increased the excavation stability by a factor of three.

Effect of fiber reinforcement on shear strength and void ratio of soft clay

“…4 and reduce the post-settlement of structures founded on soft soils using efficient drainage systems, or to improve the mechanical behavior of such problematic soils by adding chemical or biological additives. Beside the popular chemical soil stabilization techniques using lime, cement and fly-ash (Rios et al 2015(Rios et al , 2016Panchal et al 2018), geopolymerization has recently been introduced as an effective technique to enhance the strength of weak soils (Zhang et al 2012;Hoy et al 2017;Kua et al 2017). Alumina-silica geopolymers are products of chemical reactions between an alkaline solution such as sodium hydroxide (NaOH) and aluminosilicate-rich materials that contribute to the strength gaining process of the weak soils.…”

Study on Strength and Swell Behavioral Change and Properties of the Clay–Fiber Mixtures

“…Hence, new methods are still being investigated to increase the strength properties and reduce the swelling behaviors of expansive soils by using different materials and additives (Akbulut et al [5]; Al-Zubaidi et al [6]; Al-Mahbashi et al [7]; Al-Bared et al [8]). Generally, the chemical soil stabilization technique by using conventional materials such as cement, lime, and fly-ash (Panchal et al [9]; Rios et al [10,11]) is considered the most used technique. Recently, geo-polymerization (soil-polymer mixtures) has also been presented 2 of 15 as an effective technique to improve the properties of problematic soils (Zhang et al [12]; Kua et al [13]; Hoy et al [14]).…”