Wetting-Induced Settlement of Compacted-Fill Embankments

Abstract

Many highway embankments experience problematic settlements. Compression of soil under the self-weight of the embankment generally occurs during construction, but postconstruction, wetting-induced collapse can result in more long-term settlement problems, depending on climate and movement of the wetting front. A study undertaken to examine settlement associated with unsaturated soil embankments included centrifuge modeling of compacted silt embankments, laboratory testing of the embankment soil, and data interpretation with the focus on settlement prediction. A silty soil was selected to facilitate the measurement of matric suction using tensiometers. Three model embankments were constructed and tested in the Army Corps of Engineers Centrifuge Research Center in Vicksburg, Mississippi. Embankments 20 m high were simulated using centrifugal acceleration of 165 g. Embankments were constructed to achieve a relative compaction of 90 or 95 percent based on standard effort and moisture content between 2 and 5 percent dry of the optimum moisture content. Instrumentation used during self-weight compression and wetting included linear variable differential transformers and pore-pressure transducers equipped with high-air-entry porous stones. Results demonstrate the importance of the as-compacted water content and dry unit weight on the potential for wetting-induced collapse settlement. Settlement caused by self-weight compression and that caused by wetting-induced collapse are clearly discernable in results of centrifuge tests, allowing for comparison to settlement predictions. Results are discussed in light of typical compaction specifications, oedometer-based predictions, and implications for the design of compacted embankments.

Analysis of transient seepage through a river embankment by means of centrifuge modelling

“…Thus, the study of the actual hydraulic behaviour of river embankments under simulated high-water events is fundamental to realistically model its mechanical * Corresponding author: roberta.ventini@unina.it response. According to [3], two main mechanisms can cause settlements of compacted fills in partially saturated conditions: self-weight compression and wetting-induced collapse. In the case of compacted soils such as those used for river embankment construction and reinforcement, this last mechanism frequently prevails, resulting in a volumetric collapse, i.e.…”

Wetting Induced Deformation of Soils Triggering Landslides in Pakistan

“…Subsequently, these cracks may generate water leakage channels and threaten the safety of the structure (Tang et al 2016). There are many factors that significantly influence the deformation induced by wetting such as soil type, ratio of wetting, initial matric suction, degree of saturation, dry unit weight, and stress condition (Miller et al 2001;Lim and Miller 2004;Prakoso 2013;Elsharief et al 2016;and Zheng et al 2017). There are numerous studies concerning the influence of wetting on stress-strain behavior of unsaturated soils (Jennings et al 1962;Kato et al 2000;Ferber et al 2008;AiroFarulla et al 2010;Sun et al 2007;and Bishop 1961).…”

Internal Instability in Soils: A Critical Review of the Fundamentals and Ramifications

“…This phenomenon potentially exacerbates and weakens the physical and hydraulic performance of structures, subsequently causing settlements and structural deformations ( 2 ). Floodwater and cyclic traffic loads induce internal instability in highway embankments and railway subgrades, resulting in collapses and long-term settlement problems ( 3–6 ). Also, some forensic studies, for example, Rönnqvist et al ( 7 ) and Stewart and Garner ( 8 ), have reported that internal instability in soils can lead to the formation of sinkholes and piping.…”

“…This phenomenon potentially exacerbates and weakens the physical and hydraulic performance of structures, subsequently causing settlements and structural deformations (2). Floodwater and cyclic traffic loads induce internal instability in highway embankments and railway subgrades, resulting in collapses and long-term settlement problems (3)(4)(5)(6). Also, some forensic studies, for example, Ro¨nnqvist et al (7) and Stewart and Garner (8), have reported that internal instability in soils can lead to the formation of sinkholes and piping.…”