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Experimental Investigation of Root Tensile Strength for Slope Stabilization

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Abstract

Bioengineering approaches provide cost-effective ways to protect slopes against surface erosion and shallow mass movements. Indeed, vegetation is an excellent way to control slope erosion and instability of slopes. Plants play an active role both on the surface, protecting and holding soil particles, and at deeper layers, reducing pore pressure and increasing soil shear strength. The use of vegetation is particularly appropriate where soil conservation measures are needed. In the paper, a series of laboratory tests are described, together with the equipment used, to better understand plant root effects on soil shear strength and slope stability. Two species of Mediterranean plants, such as Asparagus acutifolius and Spartium junceum, were tested in the laboratory. More than 170 tensile tests have been performed on dry and saturated samples. In order to evaluate the effect of soil moisture, most several roots were also tested at different saturation ratios. Laboratory tests also included direct shear tests on root-reinforced and unreinforced samples. Comparison between reinforced and non-reinforced samples confirms the contribution of roots to improve the soil strength.

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Abbreviations

α :

Angle between the root and the normal to the sliding surface

A R :

Roots area

A :

Considered area for stability analysis

A i :

Root area in the class i

β :

Angle of the sliding surface to the horizontal

c′:

Cohesion

D b :

Root diameter into the stable soil

Δτ L :

Increment in strength due to the root

ϕ :

Friction angle

F s :

Safety factor with root contribution

F s0 :

Safety factor without root contribution

γ :

Soil unit weight

H w :

Height of the water table

H :

Height of the sliding slope

k h :

Horizontal seismic coefficient

k v :

Vertical seismic coefficient

L b :

Average length of the root apparatus into the stable zone

m :

Number of classes of roots having a same diameter

n :

Number of roots with a same diameter

p m :

Value of distributed load

σ R :

Tensile strength of the root

σ Ri :

Average root tensile strength in the class i

τ *L :

Strength increment due to roots

τ L :

Soil shear strength

τ lb :

Average value of the ultimate shear stress at the interface along the root into the stable zone

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Authors and Affiliations

  1. Department of Civil and Industrial Engineering, University of Pisa, Largo Lucio Lazzarino no. 2, 56122, Pisa, Italy

    P. P. Capilleri

  2. Department of Civil Engineering and Architecture, University of Catania, Catania, Italy

    M. Cuomo, E. Motta & M. Todaro

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  1. P. P. Capilleri
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  2. M. Cuomo
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  4. M. Todaro
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Correspondence to P. P. Capilleri.

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Capilleri, P.P., Cuomo, M., Motta, E. et al. Experimental Investigation of Root Tensile Strength for Slope Stabilization. Indian Geotech J 49, 687–697 (2019). https://doi.org/10.1007/s40098-019-00394-2

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