Вестник МГТУ, 2021, Т. 24, № 2.

Вестник МГТУ. 2021. Т. 24, № 2. С. 214-227. DOI: https://doi.org/10.21443/1560-9278-2021 -24-2-214-227 Fig. 6. Changes in the shape of the west side section of the quarry in one year. In the top figure there is the result of the 2019 shooting, in the bottom - the result of comparisons between models obtained in 2018 and 2019 (model developed by V. Shekov) Рис. 6. Изменение формы западной части карьера за год. Вверху - съемка 2019 г., снизу - результат сравнения моделей, полученных в 2018 и 2019 гг. (модель разработана В. Шековым) A detailed survey of this site has shown that some of the rocks on board hang over the filled quarry and its stability is controlled by the strength of the rocks, as shown in Fig. 7, a, or due to the wall cracks shown in Fig. 7, b. The areas shown in Fig. 7 are characterized by the fact that earlier in this place there were significant downfalls of pieces and blocks of different shapes and volumes. The remained shapeless pieces of varying volumes remain on the board of the quarry and their condition is currently undetermined. Some of them can collapse at any moment when significant loads appear on the upper edge, and some parts can be stable in the absence of loads (Fig. 8). The situation is aggravated by the presence of systemic cracks falling at the angle of 45-50 degrees towards the lake, along which some large pieces of the massif have already fallen earlier. The area represented in Fig. 7, b from the western side is the remnant of the downfallen block (the place is highlighted by a black rectangle), which is sandwiched between two cracks. The right crack at the top deflects slightly giving a wedge shape to the clamped block. In the lower part of the structure, breakaway pieces are visible, jamming the bulk of the stone hanging over them. The structure is in an extremely unstable condition and can collapse at any time if small pieces holding the overhanging block fall out. The unstable part of stone is dangerous for visitors, especially for those who constantly approach it. From the side of the tourist trail, this part looks safe, and this can deceive visitors. On our recommendation, it was strictly forbidden to approach this slope for visitors. Later, the castle stone was removed and the entire structure hung on it was collapsed managed with the removal of hanging blocks, as shown in Fig. 9. However, the collapsed mass revealed another problem - the crack along which this block is adjacent to the wall. In the block itself, you can see the cracks caused by stretching, which could be opened unpredictably. The hanging block should be dismantled and brought down into the lake as soon as possible. 219