Analysis of Vegetation Effects on Slope Stability of Embankment
American Journal of Civil Engineering
Volume 8, Issue 4, July 2020, Pages: 77-86
Received: Dec. 17, 2019;
Accepted: Dec. 26, 2019;
Published: Aug. 25, 2020
Views 48 Downloads 77
Md. Murad Hasan, Western Bangladesh Bridge Improvement Project (WBBIP), Oriental Consultant Global Limited, Jashore, Bangladesh
Mehejabin Chowdhury Ankan, Western Bangladesh Bridge Improvement Project (WBBIP), Jashore, Bangladesh
Follow on us
Embankments play a significant role in protecting cities from many natural disasters. Erosion and landslides of embankments and natural slopes are common phenomena occurring every year in Bangladesh. It has become a great concern of protecting embankments and natural slopes from failure. In many cases, traditional methods for protecting embankments and natural slopes are not effective during their designed lives. In such a condition, bio-engineering has been adopted in many countries as an effective and environment friendly measure for the protection of slopes. The role played by vegetation in improving slope stability is now well recognized. Many research works have been done in many countries on many species of trees that are locally available and suitable for the climatic and soil conditions of that country. In this study, an attempt has been made to evaluate the performance of lebbek tree and royal poincianain protecting the Rajshahi City Protection embankment. In-situ direct shear test was performed on block samples to determine the in-situ shear strength of rooted soil and soil without root. A numerical analysis has been performed to compute the factor of safety and shear strength of slope soil with root and without root. Also the effect of different types of vegetation on slope stability is observed by numerical analysis. It has been found that the values of factor of safety vary between 1.781 and 1.926 in case of slope without root whereas the values of factor of safety vary between 1.997 and 2.173 in case of slope with root. In numerical analysis, the shear strength of soil varies between 40.311 kPa to 41.782kPa in case of slope without root whereas in case of slope with root this value varies between 50.929 kPa to 52.13 kPa. The average percentage of increase in shear strength for lebbek tree root is 14.35% whereas this value for royal poinciana is 24.29%. It has been also found thatthe factor of safety of soil slopes without vegetation, with uniform vegetation, cylindrical vegetation and semi-spherical vegetation are 1.605, 1.653, 1.654 and 1.616 respectively. From the results, it is understood that plants with cylindrical root architecture increase the most significantly slope stability. It also appears that lebbek tree and royal poinciana may be low-cost and environment friendly alternative solution for the protection of embankment in Bangladesh.
Protecting Embankments, Bio-engineering, Slope Stability, Factor of Safety, Shear Strength, Numerical Analysis, Lebbek Tree, Royal Poinciana
To cite this article
Md. Murad Hasan,
Mehejabin Chowdhury Ankan,
Analysis of Vegetation Effects on Slope Stability of Embankment, American Journal of Civil Engineering.
Vol. 8, No. 4,
2020, pp. 77-86.
Copyright © 2020 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/
) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nilaweera, N. S., & Nutalaya, P. (1999). Role of tree roots in slope stabilisation. Bulletin of engineering geology and the environment, 57 (4), 337-342.
Islam, M. S., Nasrin, S., Islam, M. S., &Moury, F. R. (2013). Use of vegetation and geo-jute in erosion control of slopes in a sub-tropical climate. World Academy of Science, Engineering and Technology, 73, 1162-1170.
Abdullah, M. N., Osman, N., & Ali, F. H. (2011). Soil-root shear strength properties of some slope plants. Sains Malaysiana, 40 (10), 1065-1073.
Vishnudas, S., Savenije, H. H. G., Zaag, P., Anil, K. R., &Balan, K. (2006). The protective and attractive covering of a vegetated embankment using coir geotextiles. Hydrology and earth system sciences, 10 (4), 565-574.
Islam, M. S., Shahriar, B. A. M., &Shahin, H. M. (2013). Study on growth of vetiver grass in tropical region for slope protection. International Journal of GEOMATE, 5 (2), 729-734.
Gautam, T., “Broom Grass: Rehabilitation of Forests Degraded by Shifting Cultivation/Slash-and-Burn Agriculture”, 2015-11-25, article posted on 08 September 2015, http://www.wwfnepal.org/.
Islam, M. S. and Arifuzzaman (2010), “In-situ shear strength of vetiver rooted soil”, Bangladesh Geotechnical Conference 2010: Natural Hazards and Countermeasures in Geotechnical Engineering Dhaka, Bangladesh, pp. 274-279.
Norris, J. (2005), “Root reinforcement by hawthorn and oak roots on a highway cut-slope in Southern England”, An International Journal on Plant-Soil Relationships, Vol. 278, Issue 1-2, pp. 43-53.
Roads & Highways Department, Bangladesh (RHD).
Local Government Engineering Department, Bangladesh (LGED).