Topsoil erosion control using jute geotextile (JGT) under simulated rainfall

Abstract

The failure of road side slope, hill slope, river bank etc. due to erosion is one of the common problems in Bangladesh. Various measures have been taken to prevent soil erosion. The traditional practices for protecting the slopes are expensive and sometimes not effective due to improper design and construction faults. Use of Jute Geo-textile (JGT) is an alternative method for controlling soil erosion. Effectiveness of jute geo-textile on runoff and soil erosion for slope has been investigated. Effectiveness of using various types of JGT in different slope conditions is still required to be examined. In this study, investigations were made to check the effectiveness of JGT in controlling erosion for mild slope (1:1.5) and steep slope (1:1). Two types of JGTs (500 gsm and 700 gsm) were selected this study. Physical and hydraulic properties of the JGTs were determined at first. Models were constructed at BUET premises. Sandy soil of FM 1.18 was used for the model study which was collected from local market. D50 and D60 of the soil were 0.23mm and 0.26mm respectively. The uniformity coefficient (Cu) and coefficient of curvature (Cc) of soil were 2.36 and 1.13 respectively. The angle of friction of the soil which obtained from direct shear test under consolidated drained was 33o.Artificial rainfall was arranged using a perforated GI sheet tray. Rainfall simulation was conducted to apply a particular rainfall intensity of 150 mm/hr. A container was used for collecting eroded soil and runoff. Synthetic geotextile was used as a filter material to separate the eroded soil. Eroded soil was air dried after the separation. Also a steel frame filter was used instead of weep hole wall to support the toe of soil slopes. From model tests, it is observed that steep slope (1:1) covered with JGT is more stable than mild slope (1:1.5) covered with JGT for both types of JGT used in this research (i.e., 500 gsm and 700 gsm). It is also observed that 700 gsm jute geotextile is more effective than 500 gsm jute geotextile in respect to soil erosion by reducing surface runoff. Again, all the test data and observations suggest that open mesh JGT system reduces the eroded soil particles by 92% in comparison to a bare slope soil. Finally, it can be concluded that jute geotextile is a cost effective and sustainable solution for the protection of slope against rain-cut erosion in Bangladesh.