Effect of Degradation of Municipal Solid Waste On the Shear Strength Behavior from a Dump Site In Una Town, Himachal Pradesh

The behavior of shear strength property of municipal solid waste (MSW) during decomposition/degradation was presented in this study. The large-scale direct shear laboratory tests were performed for analyzing the variation in shear properties of fresh to decomposed waste. The physical characteristics, organic content, moisture content at different stages of degradation and increasing age were evaluated for better understanding of the mechanical response. The reduction in the organic fraction from 56% to 16.5% was observed with increase in depth. However, the unit weight increased with the degradation from 6.97 kN/m3 for fresh to 7.05-10.3 kN/m3 for degraded waste. The results obtained from the direct shear test indicated an increase in the angle of internal friction (φ) whereas cohesion (c) did not follow any pattern with degradation of waste. It was further observed that the fresh samples of MSW exhibited lower strength than degraded waste. The shear strength of waste was observed to increase with rise in finer fraction thereby also increasing the unit weight and density of the waste. The mobilized cohesion of waste was observed to vary from 31.9 kPa to 33.4 kPa with an increase in depth till 1.5 m. The results obtained from the tests were compared with the literature and the best fit shear strength parameters for the current study depending upon the degradation of waste was characterized by cohesion value 32.6 kPa and angle of internal friction of 21°.