Citation :

Rodulfo A. Macalam, "Machine Twine Coconet Reinforcement in Sandy Backfill for Mechanically Stabilized Earth Applications," International Journal of Engineering Trends and Technology (IJETT), vol. 74, no. 3, pp. 200-215, 2026. Crossref, https://doi.org/10.14445/22315381/IJETT-V74I3P115

Abstract

This study was conducted to investigate the pullout behavior of machine twine coconets reinforcement embedded in sandy backfill. It is aimed at readily available substitutes for geosynthetics for specific applications in civil engineering, like Mechanically Stabilized Earth (MSE) walls and other ground improvement techniques. The study employed an experimental research design by using four experimental phases to achieve an empirical model of the pullout interaction coefficient (𝐶𝑖) of coconet for use in the design of the MSE wall. The effects of various normal pressures (𝜎𝑛) and various specimen lengths (𝐿𝑒), on the pullout behavior of the three different coconet specimens was investigated and characterized. Results of laboratory pullout simulations revealed that the pullout resistance-displacement behavior of coconets is affected by the applied normal pressure, the type of coconet, and the specimen lengths. The stiffer coconet, such as coconet 700, requires the longest specimen length of 50 cm under the highest applied normal pressure of 31.20 kPa to attain its maximum pullout resistance of about 8.5 kN/m. While the less stiff coconet 400 attains its average pullout resistance of 6.87 kN/m at an applied normal pressure of 31.20 kPa for the specimen lengths of 30, 40, and 50 cm. In addition, the (𝐶𝑖) values were found to slightly decrease with increasing specimen length. Also, the stiffer coconet, such as coconet 700, has slightly higher values of (𝐶𝑖) than the other coconet specimens. Interestingly, the values of (𝐶𝑖) are dominantly affected by the applied normal pressures, and the values tend to decrease with increasing normal pressures. On average, (𝐶𝑖) values vary from around 1.3 at a normal pressure of 10 kPa to around 0.80 at a normal pressure of 30 kPa. Furthermore, an empirical model of (𝐶𝑖) with the normal pressure is proposed for use in the design of MSE using coconet reinforcement. Finally, this study has concluded that coconet, as far as its mechanical properties, such as the pullout resistance, can be a potential soil reinforcement for MSE applications, especially the stiffer coconet, such as the locally available coconet 700 used in this study.

Keywords

Pullout tests, Pullout resistance, Pullout interaction coefficient, Coconet, Soil reinforcement.

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