Effect of Strain Rate on Cyclic Behavior of Pond Ash Reinforced with Geocell

Abstract

This paper studies the effect shear strain on cyclic behavior of unreinforced and geocell reinforced pond ash samples. Pond ash was collected from upstream side of an ash embankment of Panki thermal power plant, Kanpur, India (seismic zone III). The size of pond ash samples was 70 mm × 140 mm. According to the size of the sample, geocells were fabricated using high density polyethylene sheets with three interconnected cells of circular cross section. A series of consolidated undrained (CU) cyclic triaxial tests at a constant loading frequency of 1 Hz were carried out on pond ash samples with and without geocell reinforcement. These tests were carried out with varying cyclic shear strain rate (0.2%, 0.3% and 0.4%) over a constant confining pressure of 50 kPa. Results show that geocell reinforced pond ash exhibit better liquefaction potential and secant shear modulus than unreinforced pond ash samples. The secant shear modulus decreases with increase in cyclic shear strain rate from 0.2% to 0.4% for both unreinforced and geocell reinforced pond ash samples. The decrease is more pronounce in unreinforced pond ash samples. The number of cycles for initiation of initial liquefaction increases about 89% to 105% for geocell reinforced pond ash samples as compared to unreinforced samples.