The paper presents some selected topics related to the role of in-hole geophysical tests in the design and construction of the Zelazny Most depository, one of the world’ s largest copper tailings disposal, in South-West Poland, owned by KGHM (Polish acronym for Copper Mine and Mill Company). Considering the dimension of the object dealt with and the volume of the tailings already stored, presently ~ 618x106m3, one of the most demanding challenges to geotechnical engineers involved with its design and construction concentrates on its safety with respect to the hazard of flow failure. To ensure the overall security of the surrounding area, the safe development of the disposal is overseen by an International Board of Experts (IBE) by applying the R. Peck (1969, 1980) observational method. After mentioning the role of geophysical in-hole tests in geotechnical design, this paper focuses on the use of seismic waves, P-wave and S-wave, in combination with dedicated consolidated undrained triaxial tests to evaluate the susceptibility of tailings to liquefaction in fully and partly saturated state. The following selected topics, oriented towards practitioners interests, are discussed: brief description of Zelazny Most tailings depository; characterization of propagation of S-waves in down-hole mode to determine the shear wave velocity Vs ; mapping the state of the tailings with depth by propagation P-waves from 16 cross-hole station, to distinguish between fully from near to saturated tailings and the greater increase of the liquefaction resistance of partly saturated with respect to fully saturated tailings.
Subjects: Copper tailings, tailings disposal, in-hole geophysical tests, partly saturated tailings, gel-push sampler
Author: Michele Jamiolkowski Emeritus Professor and Andrea Masella, Project Manager
Publisher: DFI, EFFC