Ultrasound Study of the Quality of Consolidation Grouting Works for Retaining Rocks in Underground Structures
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Vol. 54, No. 3, September, 2020
ULTRASOUND STUDY OF THE QUALITY OF CONSOLIDATION GROUTING WORKS FOR RETAINING ROCKS IN UNDERGROUND STRUCTURES S. K. Davlatshoev1 Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 4, April 2020, pp. 2 – 7
The effectiveness of consolidation grouting for retaining surrounding rocks of the turbine hall at the Rogun hydro power plant (HPP) on the Vakhsh River in southern Tajikistan is evaluated. The ultrasonic method is used to examine samples, informing the choice of a test site in the aleurolite zone, as well as a drilled grout and test hole scheme. The results of processing and analysis of the ultrasonic study results are presented. Keywords: consolidation grouting; test site; turbine hall; ultrasonic logging; aleurolite; test hole; geophysical surveys.
gravitational and tectonic pressures leading to the wall’s convergence. It should be noted that the response of the enclosing rock massif to the construction of the turbine hall is not limited to the processes of decompression and subsequent consolidation of the rock massif. At the same time, a convergence of the excavation walls takes place [5]. The intensity and duration of convergence are significantly different in sandstones and aleurolites (Fig. 2). While, in the case of sandstones, the convergence effectively ends six months following the completion of the massif compaction, the results of recent year observations indicate that this process continues in the case of aleurolites. For a rock massif in a stressed state of compression, unloading leads to a change in the stress state in the border zone of rocks, where stresses decrease in the radial direction but increase in the tangential direction resulting in the destruction of rocks at the excavation border [6]. According to the concept of strengthening the excavation walls, in addition to the anchoring of the massif, the consolidation grouting of the enclosing rock massif is specified. The control of the effectiveness of the grouting measures for increasing the elastic and strength characteristics of the enclosing rock massif can be ensured using geophysical methods. To this end, test sites were selected in the walls of the up- and downstream parts of the turbine hall at the Rogun HPP. The studies were carried out in the turbine hall of the Rogun HPP in 2014 by specialists from the Center for Geodynamic Surveys in Energy Industry of the Hydroproject Institute (Moscow) and LLC Gidrospetsproekt (Rogun). Investigations for the elastic and strength characteristics of rocks in under-
The turbine hall of the Rogun (hydro power plant) HPP on the Vakhsh River in southern Tajikistan has a span of 21 m, a height of 70 m, and a length of 220 m. Parallel to it, at a distance of 63 m in the axes, a transformer room is located with a span of 19 m, a height of 37 m, and a length of 182 m [1]. One of the characteristic features of the turbine hall is the presence of lithological varieties of rocks — stronger thick-bedded slabby sandstones of the K1ob2 Upper Obigarm Formation and weaker sil
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