scholarly journals Influences of root-induced soil suction and root geometry on slope stability: a centrifuge study

2017 ◽  
Vol 54 (3) ◽  
pp. 291-303 ◽  
Author(s):  
A.K. Leung ◽  
V. Kamchoom ◽  
C.W.W. Ng
Keyword(s):  
Slope Stability ◽  
Soil Suction ◽  
Intense Rainfall ◽  
Centrifuge Modelling ◽  
Clayey Sand ◽  
Mechanical Reinforcement ◽  
Root Reinforcement ◽  
Real Roots ◽  
Soil Bioengineering ◽  
Transient Seepage

Soil bioengineering using vegetation has been recognised as an environmentally friendly solution for shallow slope stabilization. Plant transpiration induces suction in the soil, but its effects on slope stability are often ignored. This study investigates the influences of transpiration-induced suction and mechanical reinforcement of different root geometries (i.e., tap- and heart-shaped) to the slope stability subjected to an intense rainfall with an intensity of 70 mm/h (prototype scale; corresponding to a return period of 1000 years), via centrifuge modelling. New model roots that have scaled mechanical properties close to real roots were used to simulate transpiration-induced suction in the centrifuge. Transient seepage analyses were performed using SEEP/W to back-analyse the suction responses due to transpiration and rainfall. Subsequently, the back-analysed suction was used to assess the factor of safety of the slopes using SLOPE/W. It is revealed that heart-shaped roots provided greater stabilization effects to a 60° clayey sand slope than tap-shaped roots. The heart-shaped roots induced higher suction, leading to 14% reduction of rainfall infiltration and 6% increase in shear strength. Although transpiration-induced suction in a 45° slope was reduced to zero after the rainfall, mechanical root reinforcement was found to be sufficient to maintain slope stability.

Centrifuge modelling of soil slopes reinforced with vegetation

2010 ◽  
Vol 47 (12) ◽  
pp. 1415-1430 ◽  
Author(s):  
R. Sonnenberg ◽  
M. F. Bransby ◽  
P. D. Hallett ◽  
A. G. Bengough ◽  
S. B. Mickovski ◽  
...  
Keyword(s):  
Slope Failure ◽  
Centrifuge Modelling ◽  
Mechanical Reinforcement ◽  
Root Reinforcement ◽  
Geotechnical Centrifuge ◽  
Post Test ◽  
Reinforcement Model ◽  
Root Properties ◽  
Centrifuge Model Tests ◽  
Made In

This paper reports a series of geotechnical centrifuge model tests conducted to investigate the mechanical reinforcement of slopes by vegetation. Some of the model slopes contained young willow trees, which were grown in controlled conditions to provide different root distributions and mechanical properties. Slopes were brought to failure in the centrifuge by increasing water pressures. The failure mechanisms were investigated photographically and using post-test excavation. By measuring the soil properties and pore pressures in each test when failure occurred, slope stability calculations could be performed for each slope failure. These back-calculations of stability suggest that only a small amount of reinforcement was provided by the root system even when it was grown for 290 days before testing. In contrast, the use of the measured root properties and a commonly used root reinforcement model suggests that significant reinforcement should have been provided by the roots. This disparity is probably due to either inappropriate assumptions made in the root reinforcement model or soil alteration produced by root growth. Such disparities may exist in the application of root reinforcement models to full-scale slopes and therefore require additional study. The modelling technique outlined in this paper is suitable for further investigation of root mechanical interactions with slopes.

scholarly journals Wurzelverstärkung und Hangstabilitätsberechnungen: ein Überblick

2019 ◽  
Vol 170 (6) ◽  
pp. 292-302
Author(s):  
Massimiliano Schwarz
Keyword(s):  
Forest Management ◽  
Slope Stability ◽  
Lateral Root ◽  
Forest Cover ◽  
Root Reinforcement ◽  
Online Tool ◽  
Protection Forest ◽  
Soil Bioengineering ◽  
Spatially Distributed ◽  
Landslide Body

Root reinforcement and slope stability modeling: a review Rooted soils are comparable to composite materials that have very heterogeneous mechanical properties. The analysis and quantification of these properties and their change over time is very time-consuming and complex, but central to many practice-relevant aspects of soil bioengineering and protection forest management. The article summarizes recent knowledge and approaches for the quantification of so-called root reinforcement – the reinforcement of soil by roots – and its implementation in slope stability models. Root reinforcement involves four mechanisms: basal root reinforcement, lateral root reinforcement under tension, lateral root reinforcement under pressure, and stiffening of the landslide body. Recently, the SlideforNET/SlideforMAP and SOSlope models have been developed for practical use. SlideforNET is an online tool that allows to assess the likelihood of shallow landslides and the protective effect of forest cover within a few minutes. SlideforMAP is based on the same approach as SlideforNET, but is spatially distributed and takes into account the forest structure in a catchment area or a region in detail. In particular, SOSlope supports the quantification of the protective effectiveness of forest stands as well as the planning of protection forest management and of soil bioengineering measures. Initial pilot projects show that the models enable the transition from a “qualitative” to a “quantitative” soil bioengineering.

Root reinforcement in plantations of Cryptomeria japonica D. Don: effect of tree age and stand structure on slope stability

2008 ◽  
Vol 256 (8) ◽  
pp. 1517-1526 ◽  
Author(s):  
Marie Genet ◽  
Nomessi Kokutse ◽  
Alexia Stokes ◽  
Thierry Fourcaud ◽  
Xiaohu Cai ◽  
...  
Keyword(s):  
Slope Stability ◽  
Cryptomeria Japonica ◽  
Stand Structure ◽  
Tree Age ◽  
Root Reinforcement

scholarly journals Vector Sum Analysis Method of Loess Slope Stability under Rising Groundwater Level Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Haibin Xue ◽  
Faning Dang ◽  
Yanlong Li ◽  
Xiaotao Yin ◽  
Man Lei
Keyword(s):  
Spatial Distribution ◽  
Slope Stability ◽  
Groundwater Level ◽  
Analysis Method ◽  
Seepage Analysis ◽  
Force Method ◽  
Loess Slope ◽  
Structural Deterioration ◽  
Transient Seepage ◽  
Vector Sum

The stability analysis of loess slopes with a rising groundwater level is a problem that integrates unsaturated and transient seepage, stress analysis, and stability prediction. For this purpose, a sequentially coupled method of seepage-softening-stability was used. First, seepage analysis of a loess slope with a rising groundwater level was conducted according to unsaturated and transient seepage analysis theory. Second, the spatial distribution of the deformation and strength parameters of the soil, both of which were based on the calculated results of the seepage analysis, were adjusted according to the water-induced structural deterioration equation. Third, the vector sum analysis method of loess slope stability, which was based on the temporal-spatial distribution laws of effective unit weight, elastic modulus, Poisson’s ratio, cohesion, internal friction angle, and seepage force, was performed by the body force method. To verify the proposed method, the limit equilibrium method of loess slope stability was conducted by the surface force method. Finally, the progressive failure process of a loess slope with a rising groundwater level on the White Deer Plain was presented as an example. A comparison analysis of the calculated results of the two methods revealed that the proposed method was reasonable and reliable.

scholarly journals Hydro-Mechanical Effects of Several Riparian Vegetation Combinations on the Streambank Stability—A Benchmark Case in Southeastern Norway

2021 ◽  
Vol 13 (7) ◽  
pp. 4046
Author(s):  
Vittoria Capobianco ◽  
Kate Robinson ◽  
Bjørn Kalsnes ◽  
Christina Ekeheien ◽  
Øyvind Høydal
Keyword(s):  
Slope Stability ◽  
Methodological Approach ◽  
River System ◽  
Flood Management ◽  
Natural State ◽  
Mechanical Reinforcement ◽  
Climate Conditions ◽  
Salix Caprea ◽  
Stability Of Slopes ◽  
The Stability

Vegetation can be used as a nature-based solution (NBS) to restore rivers and mitigate water-triggered processes along streambanks. Roots are well known to improve the overall stability of slopes through hydro-mechanical reinforcement within the rooted zone. Vegetation-based solutions require the selection of species that are most suitable for specific locations, and they are aimed at restoring the natural state and function of river systems in support of biodiversity, flood management, and landscape development. Selecting a combination of different species along different zones of the riverbank can improve the conditions for the river system with regard to biodiversity and stability. Therefore, more studies are needed to investigate how the combination of a variety of different plant species can improve the stability of the riverbank. This paper presents a methodological approach for slope stability modeling including vegetation as well as the results obtained from a series of slope stability calculations adopting the proposed methodology. The analyses were carried out for critical shallow (≤3 m deep) shear planes of ideal benchmark slopes covered with four different plant combinations—(i) only grass, (ii) grass and shrubs, (iii) only trees, and (iv) trees, shrubs, and grass—for species typically found along streams in southeastern Norway. In this desk study, two types of tree species were selected, namely Norway spruce (Picea abies) and Downy birch (Betula pubescens). The Goat willow (Salix caprea) was selected as a shrub, while a common mixed-grass was chosen as grass. Vegetation features were obtained from the literature. The methodology was used for two main cases: (1) considering only the mechanical contribution of vegetation and (2) considering both the hydrological and mechanical reinforcement of vegetation. The main outcome of the numerical modeling showed that the purely mechanical contribution of vegetation to slope stability could not be decoupled from the hydrological reinforcement in order to have a realistic assessment of the roots improvement to the stability. The most critical shear surfaces occurred below the rooted zone in all cases, and the best performance was obtained using the combinations including trees. Considering the typical climate conditions in Norway, the hydro-mechanical reinforcement was most effective in the spring and for combinations including low height vegetation (i.e., grass and shrubs). The study concludes that a mixed combination of vegetation (trees, shrubs, and grass) is the most suitable for reaching the highest hydro-mechanical reinforcement of streambanks, together with erosion protection and boosting the ecosystem biodiversity. The current study can help practitioners determine which vegetation cover combination is appropriate for improving the current stability of a streambank with restoration practices.

scholarly journals FUNCTION OF INTERCEPTION, EVAPOTRANSPIRATION AND ROOT REINFORCEMENT OF PLANT ON SLOPE STABILIZATION

2020 ◽  
Vol 15 (1) ◽  
pp. 19-26
Author(s):  
Euthalia Hanggari Sittadewi
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Tree Canopy ◽  
Shear Stresses ◽  
Slope Stabilization ◽  
Root Reinforcement ◽  
Soil Shear Strength ◽  
Positive Effect

The ability of plants to carry out the functions of interception, evapotranspiration and root reinforcement provides an effective and contributes to an increase in slope stability. Canopy has a role in the process of interception related to the reduction of amount the infiltrated water and the rapid fulfilment of soil moisture. Through the evapotranspiration mechanism, plants can reduce pore water pressure in the soil so that the trigger force for landslides can be reduced and the soil will be more stable. The roots mechanically strengthen the soil, through the transfer of shear stresses in the soil into tensile resistance in the roots. Roots also bind soil particles and increase surface roughness, thereby reducing the process of soil displacement or erosion. There is a positive relationship between the density of the tree canopy with the value of rainfall interception, evapotranspiration with a decrease in pore water pressure in the soil and the ability of root anchoring and binding with an increase in soil shear strength, indicating that the function of interception, evapotranspiration and strengthening of plant roots have a positive effect on increasing slope stability. Plants selection that considers the level of interception, the rate of evapotranspiration and root reinforcement by adjusting environmental and slopes conditions will determine the success of slope stabilization efforts by vegetative methods.Keywords : interception, evapotranspiration, root reinforcement, slope stabilization.

scholarly journals Effect of Oriental beech root reinforcement on slope stability (Hyrcanian Forest, Iran)

2014 ◽  
Vol 60 (No. 4) ◽  
pp. 166-173 ◽  
Author(s):  
E. Abdi
Keyword(s):  
Tensile Strength ◽  
Slope Stability ◽  
Root Distribution ◽  
Factor Of Safety ◽  
Power Relationship ◽  
Strength Increase ◽  
Hyrcanian Forest ◽  
Reinforcement Effect ◽  
Root Reinforcement ◽  
Oriental Beech

Vegetation significantly affects hillslope mechanical properties related to shallow landslides and slope stability. The objective of this study was to investigate and quantify the effect of Oriental beech root reinforcement on slope stability. A part of Hyrcanian forest in northern Iran was selected for the study area. To do the research, the Wu model (WM) was used and data related to the distribution and tensile strength of Oriental beech roots were collected. Root distribution was assessed using the concept of the root area ratio and trenching method. Laboratory tensile tests were conducted on fresh roots for strength characteristics. The factor of safety was calculated for two different soil thicknesses (1 and 2 m) and slope gradients between 10 and 45&deg;. The results showed that the root distribution generally decreased with increasing soil depth and the mean root strength value was 38.23 &plusmn; 1.19 MPa for 0.35&ndash;5.60 mm diameter range. The results verified a power relationship between tensile strength and root diameter. The reinforcement effect (C<sub>r</sub>) decreased with depth and the strongest reinforcement effect was in the second soil layer (10&ndash;20 cm) which showed a shear strength increase of 1.47 kPa. The increased factor of safety due to the presence of roots in one- and two-metre soil thicknesses was 27&ndash;44% and 15&ndash;26%, respectively. The improvement effect of roots was increased with increasing slope gradient and shallower soil thicknesses. &nbsp; &nbsp;

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