Tensile strength of a compacted vegetated soil: Laboratory results and reinforcement interpretation

Fraccica, Alessandro; Romero, E.; Fourcaud, Thierry

doi:10.1016/j.gete.2021.100303

Cited by 10 publications

(6 citation statements)

References 65 publications

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“…As it is possible to see, minor effects of vegetation on soil friction angle were observed, while roots contributed to increase the cohesion term. Friction values were in line with those observed in the same soil subjected to other stress paths [14,30]. The calibrated γ parameter was far below the 1.2 evaluated by [31] and inferred from backanalysis on landslide vegetated scarps (where roots have been potentially subjected to larger deformations than in triaxial compressions).…”

Section: Reinforcement Interpretationsupporting

confidence: 77%

Large cell triaxial tests of a partially saturated soil with vegetation

2023

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The use of vegetation roots as a nature-based solution against landslides and erosion requires the definition of sample preparation protocols and adoption of equipment that allows testing representative elementary volumes of the whole soil-root system. For this purpose, large cell triaxial compression tests were carried out on fallow and vegetated samples at different degrees of saturation. Samples were prepared by static compaction of a silty sand and seeded with Cynodon dactylon. The hydraulic state during plants growth was controlled and reproduced on bare soil samples. After isotropic compressions, the shearing phase was carried out at very low confining stresses (i.e., below 50 kPa). Tests were deemed to be comparable by assessing the normalised volume of roots with respect to soil, after shearing. For a given confining stress, soil samples with higher matric suction exhibited higher shear strength, furtherly increased by roots. The stress-strain behaviour observed in the vegetated soil systematically changed, when comparing tests at low and high matric suction values, due to the different mechanisms of vegetation reinforcement depending on the hydraulic state at the soil-root interface. The results were successfully interpreted within a failure criterion and skeleton stress framework for partially saturated soils, considering soil suction, degree of saturation, soil microstructure and the normalised volume of roots.

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Section: Reinforcement Interpretationsupporting

confidence: 77%

Large cell triaxial tests of a partially saturated soil with vegetation

2023

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“…c'r = 0.3 σt,r RAR 2 which resulted in 63 kPa in the first 0.3 m from the ground surface and 17 kPa between 0.3 and 1.0 m depth. Soil friction was left unvaried, in agreement with many literature studies [6][7][8][9]. The water saturated permeability variation induced on soil by roots was calculated based on correlations between RLD, kw,sat and macropore void ratio over total void ratio proposed by [13]).…”

Section: Vegetation Characteristics and Their Impacts On Soil Parameterssupporting

confidence: 66%

The impact of soil-vegetation-atmosphere interaction on a landslide initiation under torrential storms: a case study

Fraccica

Romero

Fallas³

2023

E3S Web of Conf.

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Vegetation has long been used in geotechnical engineering to protect slopes from surface instability phenomena. However, its effects remain difficult to quantify, given the diversity of plants in situ, the variability of their morpho-mechanical characteristics and their impact on soil hydraulic states. For this purpose, the case of a landslide that occurred following torrential rains in Costa Rica was analysed. After the geotechnical characterisation of the soils affected by the movement, the plant species and their main morpho-mechanical characteristics were identified. These characteristics were used to evaluate the changes in the hydromechanical parameters of the soil due to the presence of the roots, and the transpiration rates generated by the plants themselves. In the FE model, a “continuum material” approach was adopted to simulate the vegetated soil numerically, jointly with a failure criterion for partially saturated soils. Using available meteorological data, the evolution of the hydraulic state of the slope in the weeks before and during the storm that caused the landslide was simulated, comparing the cases of vegetated and hypothetically not vegetated slopes. Results validated the observations carried out on the site and confirmed the hydromechanical effects of plants in delaying in time the triggering of the landslide.

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“…11(i)). To quantify the SU propagation from one step to the other, a SU magnification factor (SU-MF) is defined: (9) where RE i,α is the RE of an output (i) of CT-IBA at a specific α; RE r,α is the RE of an output r along the same SU propagation path of the output i. SU-MF = 1 means the same SU between the two steps of CT-IBA. SU-MF higher than 1 means a magnification of SU from one step of CT-IBA to the next.…”

Section: Measurements Of Segmentation Uncertaintymentioning

confidence: 99%

“…Investigation on mechanical soil-root interaction have been extensively conducted since 1970s and are still a topic of major interest nowadays. Recent advancements include the uses of classic elastoplastic framework [5,6] and fabric anisotropy [7,8] to interpret and understand the hydromechanical responses of saturated and unsaturated rooted soils observed in the * Corresponding author: ceanthony@ust.hk laboratory when subject to different stress paths (triaxial compression and triaxial extension [3]; direct tension [9]). Advanced numerical modelling means [4,10] have also been developed to capture the soil-root load transfer mechanisms at their interface for more accurate modelling of vegetation-related problems such as the stability of slopes [11] and trees [4].…”

Section: Introductionmentioning

confidence: 99%

When nature meets technology: AI-informed discovery of soil-water-root physical interaction

2023

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Nature-based solution using vegetation has been considered as a sustainable and environmentally friendly approach to improve slope performance through root reinforcement and variations of soil matric suction upon transpiration. During plant growth, roots explore soil pore space. How fundamentally the pore structure might evolve with time following root growth dynamics and how this dynamic soil-root interaction may modify the hydraulic properties of unsaturated soils remain unclear. This paper reports the use of advanced technologies including artificial intelligence (AI) to aid the discovery of soil-root-water physical interaction and the characterisation of the hydraulic properties of rooted soils. A newly developed miniature unsaturated triaxial apparatus that enables rooted soil samples to subject to simultaneous in-situ loading and X-ray imaging is introduced. An AI-informed image processing technique is illustrated, aiming to enhance the reliability of phase segmentation of X-ray computer tomography (CT) images of four-phase unsaturated rooted soils for quantifying 3-D pore structure and root phenotype. New discoveries of how roots interact with the pore space, including the dynamic changes in the distribution, orientation and connectivity of soil pore sizes, and how this pore-level information can be used to explain the hydraulic properties are discussed.

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Tensile strength of a compacted vegetated soil: Laboratory results and reinforcement interpretation

Cited by 10 publications

References 65 publications

Large cell triaxial tests of a partially saturated soil with vegetation

Large cell triaxial tests of a partially saturated soil with vegetation

The impact of soil-vegetation-atmosphere interaction on a landslide initiation under torrential storms: a case study

When nature meets technology: AI-informed discovery of soil-water-root physical interaction

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