Slope stability analysis of underground water induced failure for kestelek open pit boron mine in Turkey

A landslide occurred in February 2010 in the northwestern part of a boron mine that has been operated by Eti Mine in Kestelek, Bursa, Turkey. It has been decided to investigate The landslide by numerical analysis methods. The formations which are alluvium, marl, calcareous, tuff, conclomera, and boron were worked out to cross sections. 3 boreholes were drilled to understand water conditions which are in-situ permeabilities and phreatic water level. Samples from the boreholes were tested to determine cohesion, internal friction angle, unit volume weight, modulus of elasticity, and permeability of the formations. After that, natural status was investigated and the results show that water, which comes from a river, flows through alluvium strata and inside the calcareous formation that causes sliding. After that, jet grout columns decided to be applied to the site along all the sliding area. Numerical analysis was applied to revised cross section with jet grout and results show that water flow field decreases to 27.48×10-9 m/s while total discharge is also going down to 0.011 m3/day/m. These results are also supported by total displacement and effective stress distributions which are also decreasing by the application of the jet grout columns to the landslide area.