Back analysis of rock mass behavior of the Quintner Limestone at the Gonzen mine near Sargans, Switzerland

摘要

Iron ore has been mined from Gonzen mine, in Sargans, Switzerland, since Roman times. Thernmine has been inactive since it closed in 1966. Observations of different failure types have been used to calibraternthe likely stress field using continuum models. Observed failures included, pillar instability averaging 0.7mrndeep, intersection spalling, roof collapse, and stope collapse. The latter two being localized observations. A K_orn(horizontal/vertical stress) ratio between 0.8–0.9 was found to adequately capture the observed depths of failurernfor the pillar and intersection models. The localized roof and stope collapse models required the inclusion ofrnbedding weakness planes to induce and localize yielding which could correctly capture the region of failure,rnhowever, the dimensions could not be correctly captured. The 2-dimensional models calibrated to the pillarrninstability and intersection spalling can be used as a starting point for more complex 3-dimensional models,rnwhich can represent the complex stress field, influenced locally by the mine openings and faulting. This workrnis part of a large study of the behavior of limestone, with a particular focus on the long term influences onrnexcavation stability.