A fundamental approach to mobility by studying deformations and stresses in a soil as a wheel moves is described. A driven rigid model wheel was constructed to run over a sample of amorphous granular peat. Metal markers were placed throughout the peat and records of their movements, using an X-ray technique, were obtained as the wheel travelled over the peat. The markers moved in cardioids (heart shapes). The marker movement for any location within the sample was obtained from relationships which existed between the movement of the markers and the positions of the wheel.The trajectories of the principal stresses were determined from the deformations by a graphical method. Using an assumption regarding the angle of internal friction for this peat, the surfaces of maximum shear were obtained. The surfaces of maximum shear resembled the configurations associated with slope stability problems in soil mechanics.
Finite element analyses of slope stability problems using non-associated plasticity