• Muhammad Safdar Earthquake Engineering Center, Department of Civil Engineering, University of Engineering and Technology, Peshawar
  • Tim Newson Department of Civil and Environmental Engineering, Western University, London Ontario, Canada


Back pressure, Saturation, Fibre reinforced, Cemented Toyoura sand, Cavitation; Stress-strain, Pore water pressure


This study is focused on understanding the fundamental behaviour of undrained shear strength of fiber reinforced cemented Toyoura sand under varying back pressure conditions using triaxial apparatus. In this study, sand samples with dimensions of 50 mm diameter and height of 100 mm were prepared to a target dry density value (e.g., = 1.489 g/cm3) using Toyoura sand mixtures. Triaxial specimens were prepared using the under-compaction moist tamping technique. Unreinforced, fiber, cemented, and fiber reinforced cemented sand samples were prepared and mixed to 10 percent of water content by dry weight of soil. The results of the deviator stress versus axial strain showed that by increasing the value of the applied back pressure increased the maximum deviator stress. For the unreinforced and reinforced specimens, the increase in peak and critical state strength (assumed at 30% axial strain) is approximately 20-100%. In addition, the results of pore water pressure and axial strain showed that specimens saturated under lower back pressures generated lower negative pore pressures and for higher back pressures, generated higher negative pore water pressures. Moreover, increase in the generation of larger negative pressure of 50% to 100%, increased the effective stresses and also increased the undrained shear strength of both unreinforced and reinforced sand specimens by 20% to 100%. Furthermore, similar increase in negative pressure was also observed for the fiber, cement, and fiber reinforced cemented specimens. One interesting feature of the data is the significance of the kink (cavitation occurrence) in stress-strain and pore water pressure response. For dilative soils (e.g., medium dense sand, fiber, cement, and fiber reinforced cemented sand), pore pressure increases and then decreases during undrained shearing. Hence, the phenomenon may be attributed to a condition of zero net change in pore pressure during shear. The point of zero net change in pore pressure during shear/cavitation might be a possible reason for the kinks observed in the stress-strain and pore pressure responses.


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How to Cite

Safdar, M., & Newson, T. . (2021). UNDRAINED SHEAR STRENGTH OF FIBER REINFORCED CEMENTED TOYOURA SAND UNDER VARYING BACK PRESSURES. Bahria University Research Journal of Earth Sciences, 6, 30–39. Retrieved from https://burjes.bahria.edu.pk/index.php/ojs/article/view/24





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