BEARING CAPACITY OF HIGHLY FRICTIONAL MATERIAL

Highly angular dense soils are known to possess secant friction angles well in excess of commonly encountered sands. These soils also exhibi t a significant variation of the friction angle over a common range of mean normal stress confinement. These characteristics raise questions regarding the ability of conventional solutions to predict bearing ca pacity and how linear strength parameters are to be determined for a n onlinear material. To examine these issues, centrifuge experiments wer e performed on shallow foundations at three embedment depths. Linear s trength parameters required for three conventional solutions were obta ined from the nonlinear envelope first by a simple averaging technique . To indirectly account for the material nonlinearity, tangent and sec ant linear strength parameters were estimated once an appropriate leve l of mean normal stress was determined. A relationship between mean no rmal stress and the resulting footing bearing capacity was developed u sing classical plasticity theory. The latter approach offered signific antly better predictions than the averaging method, yet the results in dicate the inability of conventional theories to model experimentally observed behavior.