Slope stabilization using lime piles—a case study

Abstract

Lime treatment as a mix-in-place technique has been widely and successfully used around the world to improve weak soils. Novel techniques using lime are now being developed. One such technique is the use of lime piles to stabilize shallow slopes. Recent research has investigated the reaction mechanisms associated with lime pile stabilization. This paper describes excavation work undertaken at two sites where previously lime piles had been installed to prevent further movement of a failing slope. Laboratory tests undertaken on the retrieved material are also presented and discussed in terms of whether/how the reaction mechanisms have improved the stability of the slope. Results suggested several ground improvement mechanisms, some of which could only be relied upon in the short term. Since installation of the lime piles at both sites no further movements have been recorded, suggesting that this method of stabilization has been successful. Le traitement du mélange in-situ par la chaux a été largement utilisée à travers le monde, dans le but d'améliorer les caractéristiques des sols mous. Des nouvelles techniques utilisant la chaux sont maintenant bien développées. L'une d'entre elles est l'utilisation des pieux à chaux afin de stabilizer les talus peu profonds. Les recherches récentes ont examiné les mécanismes de réaction associées à la stabilité du pieux à chaux. Cet article décrit les travaux d'excavation qui ont été realisés sur deux sites où les pieux à chaux etaient déjà installés, afin de réduire les mouvements du talus en question. Des essais en laboratoire ont été réalisés sur ces matériaux récuperés dont les résultats sont preséntés, et analysés en fonction de l'évaluation de ces mécanismes de réaction vis à vis de la stabilité du talus. A l'issue de ces résultats, plusieurs mécanismes d'amélioration des terrains ont été proposés, quelques-uns d'entre eux sont valable uniquement à courtterme. Aucun mouvement n'a été enregistré suite à l'installation de ces pieux à chaux sur les deux sites, cette methode de stabilization s'est donc révélée fiable.

Swell–shrink behaviour of lime precipitation treated soil

“…The unconfined compressive strength of untreated and lime precipitation treated specimens was determined after the first, second, third and fourth cycle of wetting. Swell-shrink behaviour of lime precipitation treated soil Thyagaraj and Zodinsanga to occur (Barker et al, 2006;Boardman et al, 2001;Rogers et al, 2000). Figure 2(b) plots the variations in liquid limit, plastic limit, shrinkage limit and plasticity index with percentage lime precipitation occurring (calculated) on sequential mixing of calcium chloride and sodium hydroxide solutions with expansive soil.…”

“…14) of the treated specimens were conducive to the occurrence of pozzolanic reactions (Table 4). According to Barker et al (2006), Boardman et al (2001) and Rogers et al (2000), the dissolution of silica (SiO 2 ) and alumina (Al 2 O 3 ) from the clay lattice begins at pH 8 . 0, and at pH of about 10 .…”

“…0, and at pH of about 10 . 0 maximum dissolution occurred (Barker et al, 2006;Boardman et al, 2001;Rogers et al, 2000). The dissolved alumina and silica combine with calcium ions, and this leads to the formation of calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH), which cements the clay particles together and increases the strength (Barker et al, 2006;Diamond et al, 1963;Eades and Grim, 1960;Rajasekaran and Rao, 1998;Wang et al, 1963).…”

Uniformity of lime-cement columns for deep mixing: a field study

“…Molecular diffusion, as a part of the mixing process, has been studied mainly in the unstabilised soil around the columns, both in the laboratory (e.g. Glendinning, 1994, 1997;Mathew and Narasimha Rao, 1997;Rajasekaran and Narasimha Rao, 1997) and in the field (Rogers et al, 2000). The binder can also spread by fractures caused by the mixing tool and by hydraulic (or pneumatic) fracturing (Shen and Miura, 1999).…”

Rapid Stabilization of Sands with Deep Mixing Method Using Polyester

“…Commonly, two different techniques are utilized; column installation and slurry pressure injection. These techniques decrease soil moisture contents thereby reducing shrinkage/swelling and enhancing strength and compaction properties [3,4,[8][9][10][11][12].…”