Chersky Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia

E. K. Romanova, Researcher, Candidate of Engineering Sciences, helconst@mail.ru
D. E. Soloviev, Senior Researcher, Candidate of Engineering Sciences
V. V. Kiselev, Senior Researcher, Candidate of Engineering Sciences

Mirny Polytechnic Institute–Division of the Ammosov North-Eastern Federal University, Mirny, Russia

A. S. Lvov, Senior Lecturer

The study addresses stability of pitwall and bench crests in open pit kimberlite mines in the permafrost zone. The results of the study in pitwall and bench crest sustainability ensured by hydro- and thermal insulation are presented. The domestic experience gained in construction of heat shielding from foamed plastics for the pitwall protection from thawing at open pit kimberlite mines in the permafrost zone is described. For the efficiency evaluation of the method and its implementation optimization, a two-dimensional mathematical model of heating and humidification in pitwall rock mass, saturated and unsaturated with water, is developed. The model takes into account the phase transition of moisture and the use of hydro- and thermal insulation. The mathematical model is solved using the finite-difference method, and allows long-term prediction of the formation of temperature and humidity fields in pitwall rock mass depending on various climatic conditions and pit design parameters. Based on this mathematical model, a technique is developed for selecting optimum parameters of hydro- and thermal insulation to preserve yearround freeze of rocks under bench crests. The technique is implemented as a Microsoft Windows OS application and is a computer software package consisting of two functionally interconnected blocks: a temperature and water regime block and an optimization block. The numerical experiments were carried out as a case-study of an open pit kimberlite mine in the Mirny district of the Republic of Sakha (Yakutia). The studies proved effectiveness of hydro- and thermal insulation as the pitwall thawing protection in the permafrost zone by means of maintenance of year-round freeze of pitwall rock mass. The problem solution on optimization of hydro- and thermal insulation ensuring pitwall slope stability in the permafrost at a significantly reduced material cost is described.
The research was carried out under the state contract with the Ministry of Science and Higher Education of the Russian Federation, Topic No. 0297-2021-0021, State Registration No. 122011800083-0, and with equipment sharing at the Center for Shared Use of the Yakutsk Science Center, Siberian Branch, Russian Academy of Sciences, Grant No. 13.CKP.21.0016.

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