Active and Passive Seismic as an Indicator of Large Equipment Interactions with the Oil Sand

The strain softening of oil sand in the underfoot of ultra class mobile mining equipment, due to the loading action of large mobile mining equipment such as trucks and shovels, yields a highly unstable condition for the operation of this ultra-class equipment. Soft ground conditions in oil sand, due to the low stiffness of the material a condition especially present in the summer, can cause high rack, pitch, and roll in trucks, leading to fatigue failure in structural components. For shovels, poor ground stability can cause twists in car bodies and undercarriages, resulting in major damages. Track and shovel frame failures due to this instability result in high maintenance costs. The authors carried out a geophysical study of the oil sand in order to evaluate the ground conditions under large mobile mining equipment. A geophysical investigation performed in summer 2001 encountered 6–8 m of thick soft material, commensurate with very low velocities, caused by the loosening of the surface material by heavy mining machinery and excavation; and a transition zone of up to 25–26 m depth approaching the in situ oil sand below. The depth of the oil sand zones can be calculated by using the refraction analysis technique. Spectral Analysis of Surface Waves was used to estimate the ground stiffness. A new technique is proposed to evaluate the changing ground stiffness during the use of ultra-class mobile mining equipment.