For Shear Joy

Overview

Objectives/Goals To determine the effects of adding recyclable materials (thermoplastic strips and polyethylene terephthalate strips) to soil behind an MSE (mechanically stabilized earth) retaining wall. Methods/Materials Scale models of MSE walls were constructed using dry, poorly graded sand as the soil type. The thermoplastic strips and polyethylene terephthalate strips were added to the soil behind the front-facing wall (scaled to size and strength of posterboard) at various addition rates. Normal force was then added to the top of the scale model as a surcharge load. The more normal force the MSE wall held, the greater the improvement in shear strength. Results The scale MSE wall with the polyethylene terephthalate strips at an addition rate of 2% held the most normal force, exhibiting the greatest increase in shear strength. The scale MSE wall with the polyethylene terephthalate strips at an addition rate of 1% held the second highest normal force, showing the second greatest increase in shear strength. The scale MSE wall with the thermoplstic strips at an addition rate of 0.2% held the third highest normal force, showing the third greatest increase in shear strength. The thermoplastic strips at an addition rate of 0.1% held the least normal force (excepting the Control) showing the least improvement in shear strength. Conclusions/Discussion Adding plastic materials to soil can greatly improve the shear strength of the soil. The more friction generated in the soil when the soil begins to slip, the stronger in shear the soil is. When placed in the soil, the plastic strips generate friction as well as cross over many shear planes, further stabilizing the soil. The more abrasive the plastic strips are, the more friction they create when the soil tries to slip, and the more the increase in soil stability.

Awards (1)

• Honorable Mention

Competition history

• CSEF 2011 Applied Mechanics & Structures · Entry J0315

Resources

• CSEF project summary ↗

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