18 / 2023-05-14 07:22:03

Ensuring the safe development of a new deposit at the design stage of work

safety risk identification,tectonic disturbances,geomechanic models,rockmass stability

The most important issue when planning the development of a deposit is the identification of risks for the safe conduct of mining operations. To do this, when choosing a mining system, it is necessary to know not only the specifics of the geological characteristics of the proposed deposit for development, but also to take into account its geomechanical conditions. The purpose of the research was to clarify the features of the rock mass stability determined by the tectonic disturbance of the deposit and the ore field as a whole in order to adjust the proposed development project. The object of the research was the Lugiinsky deposit (Zabaikalsky Krai, Russia), which is supposed to be open-pit developed. Two natural types of ores have been identified at the deposit: gold sulfide and gold sulfide with a high content of polymetals. The gold sulfide type of ores is characteristic of the central part of the deposit, where the processes of berezitization are intensively and widely manifested. The gold sulfide type of ores with a high content of polymetals is mainly located in the northwestern part of the deposit. The main useful component of the deposit ores is gold, silver, lead and zinc are also present. The lineament analysis of the deposit area relief, carried out according to the topographical basis of 2021, revealed both multidirectional discontinuous linear structures, mainly of the north-western and north-eastern directions, and annular ones. Visual inspection of the surface within the deposit showed the presence of discontinuous faults of various ranks and systems of cracks crossing the sides of the future quarry, clearly expressed in the relief. The results of data analysis for four wells of oriented core drilling allowed us to establish the main parameters of crack systems. According to morphological features, 4 natural varieties of disturbances are identified. These are zones: tectonic collapse; tectonic crumpling; increased tectonic fracturing and vein-veined systems. Morphological types reflect the intensity of tectonic processes: the maximum is typical for tectonic clays, the minimum is for veining zones. Clays emphasize a very high degree of destruction of rocks, their complete mineral and structural transformation in the process of tectonic impact. To some extent, the features of the primary structure are preserved in the zones of disintegration, where, as a result of repeated dynamic impact, rocks are not only crushed, but also rolled. The data obtained are taken into account when compiling geological-structural and geomechanical models of the deposit within the proposed open-pit. Based on these data, a three-dimensional structural model of the studied territory is constructed. A hypothesis is made about the expected directions of stress action during the formation of the modern relief of the deposit area. Judging by the directions of the regional fault and the discontinuous structures crossing the area of the deposit, there was a redistribution of stresses. That is, before the modern direction of the stress field, there was a compression of the north-western direction, which subsequently changed to the north-eastern direction, which led to the development of linear structures of the north-western direction. The eastern part of the deposit is the most fragmented, especially in the area of articulation of linear structures with one of the annular ones, the southeastern part of which is in the least fragmented state. The evaluation of the parameters of the natural stress field showed that the magnitude of compressive stresses within the Lugiinsky deposit can reach 50 MPa. The vector of the modern main horizontal compression in the deposit area has a direction from sublatitudinal to east-northeast. The created geomechanical model of the Lugiinsky deposit showed that from the point of view of ensuring stability during the development of the deposit by open-pit, there are few most problematic areas. They are mainly confined to the zones of articulations of discontinuous structures. Apparently, in the western, northwestern and northern parts of the future open-pit, the stability of both the ledges and the side as a whole will be provided by compressive stresses acting in the rock mass of the studied area due to the presence of ring structures. Apparently, in the western, northwestern and northern parts of the future open-pit, the stability of both the ledges and the side as a whole will be provided by compressive stresses acting in the rock mass of the studied area due to the presence of ring structures. That is, in these parts of the site, it is probably possible to wrap the ledges. At the same time, the strong fragmentation of structures of different ranks in a separate section of the eastern part of the deposit in the area of intersection with the regional fault and its fins may lead to a decrease in the angles of the ledges and this part of the board as a whole. The results of the performed studies of the specifics of the tectonic disturbance of the massif, taking into account two types of ores, allowed the designers to adjust the configuration of the open-pit and the Lugiinsky deposit development system to ensure safe mining operations by increasing the stability of the sides and ledges of the open-pit.  Calculations and analysis were performed using the resources of the Center for collective use of scientific equipment "Center for processing and storing scientific data of the FEB RAS", funded by the Russian Federation in the person of the Ministry of Science and Higher Education of the Russian Federation under project No. 075-15-2021-663.