Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

Mechanical biological treatment(MBT)technology has attracted increasing attention because it can reduce the volume of waste produced.To deal with the current trend of increasing waste,MBT practices are being adopted to address waste generated in developing urban societies.In this study,a total of 20 specimens of consolidated undrained triaxial tests were conducted on waste obtained from the Hangzhou Tianziling landfill,China,to evaluate the effect of loading rate on the shear strength parameters of MBT waste.The MBT waste samples exhibited an evident strain-hardening behavior,and no peak was observed even when the axial strain exceeded 25%.Further,the shear strength increased with an increase in the loading rate;the effect of loading rate on shear strength under a low confining pressure was greater than that under a high confining pressure.Furthermore,the shear strength parameters of MBT waste were related to the loading rate.The relationship between the cohesion,internal friction angle,and logarithm of the loading rate could be fitted to a linear relationship,which was established in this study.Finally,the ranges of shear strength parameters cohesion c and effective cohesion c′were determined as 1.0–8.2 kPa and 2.1–14.9 kPa,respectively;the ranges of the internal friction angleφand effective internal friction angleφ’were determined as 16.2°–29°and 19.8°–43.9°,respectively.These results could be used as a valuable reference for conducting stability analyses of MBT landfills.