Slope-stability failures have occurred in several improper landfills and illegal
dumping sites. To investigate the shear response of municipal solid waste (MSW), it is
significant to consider the stability of dumping site and landfill design. In the present paper,
the shear response and shear strength of MSW recovered from four different landfill sites (in
Japan and China) were investigated using a developed in-situ direct shear test apparatus.
Moreover, the pa-per introduces the steps for preparation of undisturbed samples and test
procedures in details to determine the in-situ shear strength characteristics (c and φ) of MSW.
The in-situ experimental results indicated that the shear response of waste materials affected
by the existence of fibrous materials. In addition, the values of cohesion and friction
parameters of waste materials strongly depended on the percent of fibrous materials. Results
of geotechnical investigations and slope stability studies of landfill sites have been also
introduced.