VNIPIpromtekhnologii JSC, Moscow, Russia:

A. M. Ioffe, Head of laboratory, Candidate of Engineering Sciences
D. V. Velichko, Leading Engineer, Velichko.D.V@vnipipt.ru
A. V. Seleznev, Head of Mining Research Department, Candidate of Engineering Sciences
E. S. Mironova, Leading Engineer

In the late 1990s–early 2000s, deformation processes became active in the southwest and south areas of Urtui pitwall, with instability of individual benches and vast pitwall sites. Until certain time, deformation run with local landslides and rock falls of the pit slopes. In 2005 deformation processes swept the whole height of the southwest pitwall. After undermining the coal benches which acted as toes, deformations became active at the pitwall top. Since July to October of 2005, velocities of displacement in the landslide sites increased from 200 to 400–500 mm/day. The key causes of the pitwall instability include high water content of rocks and weak contacts which d ip toward the mined-out void. A substantial promotion of deformation is owing to active suffusion with ejection of fine particles in places of groundwater discharge in the pitwall, and one of the major complicating factors and causes of hazardous processes is the paleochannels for most underflows in quaternary deposits. The near-surface geological and geotechnical and hydrogeological conditions in the area of deformations in the western pitwall are characterized as complex. During the studies, the comprehensive geotechnical analysis of the landslide pitwall was carried out, and the main causes of displacements were formulated. The numerical model of landslide sites was constructed and calibrated. On the basis of the modeling results, the recommendations on stability of the landslide sites were evolved. The add-on stabilization measures included construction of fill counterforces along and across the landslide sites. The check calculation of the parameters of the counterforces was carried out. On the ground of the numerical modeling and hydrogeological data analysis, the rock mass drainage recommendations were formulated.

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