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ROOT STRENGTH MEASUREMENTS OF VETIVER AND RUZI GRASSES Chairat Teerawattanasuk; Jindarat Maneecharoen; Dennes T. Bergado; Panich Voottipruex; Le Gia Lam
Lowland Technology International Vol 16 No 2, Dec (2014)
Publisher : International Association of Lowland Technology

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Abstract

This paper aims to study effect of roots of vegetation on the stability of soil along slopes and also soil erosion. The effects of root reinforcement depend on the morphological characteristics of the root system, the tensile strength of grass roots, and the spatial distribution of the roots in the soil. The experiments were carried out to evaluate the root tensile strength of two different grasses namely: Vetiver and Ruzi grasses, by conducting the laboratory tensile tests and field direct shear tests. For each type of grass, single root specimens were sampled and tested for their ultimate tensile strength and Young’s modulus in the laboratory tests. The results of laboratory tests revealed the significant correlations between root diameter and tensile force or tensile strength and Young’s modulus of Ruzi and Vetiver grasses. In addition, large scale field direct shear tests were carried out involving roots of Vetiver and Ruzi grasses to evaluate the contributions of their root systems to the soil shear strength. Vetiver roots contributed higher components of shear strength compared to Ruzi grass. However, it was found that the combination of Ruzi and Vetiver grass roots yielded much better effects than Vetiver grass alone. It can be concluded that the Vetiver grass roots help enhanced the shear strength for soil reinforcement while the short roots of Ruzi grass can help control surface soil erosion.
Maximum Tension Lines of MSE Embankments with Polymer and Metallic Reinforcements on Different Foundations Types a Dennes T. Bergado; Salisa Chaiyaput; Ray M. Basilio; Ochakkraphat Sukchaisit; Takenori Hino
Lowland Technology International Vol 23 No 3 (2021): Lowland Technology International Journal
Publisher : International Association of Lowland Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.0001/ialt_lti.v23i3.999

Abstract

Four full scale and fully instrumented mechanically stabilized earth (MSE) test embankments were constructed to 6 m high for analyses and comparison of their behaviour, namely: one on hard ground, one on DCM improved ground and two on soft ground. The MSE on hard ground was reinforced with strong polymer geogrid in one side as well as metallic grids and strips in the other side. The MSE on improved ground was reinforced with hexagonal grids. Due to the negligible vertical and lateral movements in hard and improved ground, the consequent maximum tension lines were observed to closely follow the bilinear Coherent Gravity Method with standard distance from the facing of 0.3H where H is the equivalent height of the reinforced embankment. Moreover, two fully instrumented MSE were constructed on soft ground having similar trapezoidal cross-sections. One embankment was reinforced with polymer geogrids and the other with steel grids. The resulting large vertical and lateral movements of both embankments have almost identical patterns. The maximum tension lines of both embankments closely resemble to that of Coherent Gravity Method but with location of the vertical line portion at closer distances of 0.1H to 0.2H from the embankment facing.