Diagnostics of the anti-seepage screen of a protective dam in permafrost on using an inverse problem with piezometric measurement data

Abstract

Using the finite elementmethod we designed and implemented a nonlinear geomechanical model of the rock mass in the vicinity of the protective dam of tailing facilities in the permafrost of the Kumtor mine (the Kyrgyz Republic). The model takes into account the information on the structure of the object, the data on the strain-strength, thermophysical and filtration properties of frozen and thawed soil, as well as on the seasonal variations in air temperature. Numerical experiments showed that, under constant external conditions, the invariant properties of the rock mass, and the position of the neutral layer, the zero isotherm separating frozen and thawed rocks reaches a stationary position in 12–15 years after filling the storage; minor damage to the antiseepage screen can lead to a vast destruction area in the body of the dam. Using synthetic data, we demonstrated the solvability of the inverse boundary-value problem of determining the timing and location of damage in the anti-seepage screen from the data of piezometric measurements at several observation wells.