Mass stabilisation near regional flood defences

Abstract

Reinforcing levees with traditional methods is becoming more difficult in the Netherlands. Often there is a lack of space near the levee or it is desired that the landscape is maintained. Because of this, alternative methods for reinforcing levees are still sought after (CUR-commissie C141, 2007). In this study, the technical feasibility of a possible alternative reinforcement method for regional flood defences is studied: mass stabilisation. Mass stabilisation is a soil improvement technique with which soft soils are mixed with a binder on site and in-place to create a stronger soil layer (Forsman et al., 2015). It is presumed that mass stabilisation requires no extra space at the levee, does not affect the landscape and requires little transportation of materials. For determining the technical feasibility of applying mass stabilisation for reinforcing regional flood defences, three criteria have been examined. First, the ability of mass stabilisation to solve a stability deficit at levees was examined using two-dimensional stability analyses. Secondly, the achievability of the required effective strength parameters in compliance with Dutch standards was examined in the laboratory. Thirdly, the practicability of mass stabilisation at levees was examined using two-dimensional stability analyses. Although the results of this thesis have shown that mass stabilisation is a technically feasible technique for reinforcing regional flood defences, further studies will be required before a definitive conclusion can be drawn. It is therefore recommended that additional analyses into the practicability are carried out and that the relationship of the properties and the variability thereof between soils stabilised in the laboratory and the field is studied.