Field Testing Method for Evaluating the Small-Strain Shear Modulus and Shear Modulus Nonlinearity of Solid Waste

Dynamic properties of solid waste are needed to reliably evaluate the seismic response of landfills. A testing method for investigating the dynamic properties of solid waste in situ has been implemented at various landfills. The field method is primarily aimed at evaluating shear wave and compression wave velocities at small strains as well as the shear modulus reduction versus shearing strain relationship of solid waste. In this study, shear modulus nonlinearity was successfully evaluated for shearing strains ranging from 10(-4) to 0.2 %. The relationship between shear modulus and shearing strain was investigated by applying dynamic horizontal loads applied by a mobile field shaker at the waste surface in a staged-loading sequence. The solid waste response was measured with a buried array of three-component geophones. The testing method also permitted in situ assessment of the effect of confining stress and waste variability on the dynamic properties of solid waste. Load-settlement measurements and in situ unit weight measurements were also made. Testing equipment, field setup, testing procedure, data analysis, and examples of test results are presented.