6 research outputs found
About the ice-rock collapse from the northern slope of Mt. Dykhtau on August 12, 2023 and the potential threat of collapse from the slope of Mt. Dzhangitau (Cherek-Bezengiysky River basin, Central Caucasus)
No full textThe causes and consequences of the ice-rock fall that occurred in 2023 on the Mount Dykhtau (Side ridge of the Greater Caucasus) are analyzed. This happened in the early morning of August 12, 2023 on the northern slope of Mt. Dykhtau (5.204.7 m a. s.l.) in the upper reaches of the Mizhirgi River valley of the Cherek Bezengiysky River basin at the altitude of about 4.400 m. The analysis of Sentinel-2 and Landsat-7 ETM+ satellite images of different times made possible to reveal the place where a block of ice had fallen from the hanging glacier, and to determine the area affected by this ice-rock block which volume was estimated as close to 0.9-1.0 million m3 and a distance of the runout about 2.3 km. As a result of the collapse, a group of tourists were injured, one of whom died. Investigation of the dynamics of the collapse site for the period 2015–2023 showed that earlier in the period September 3 – November 12, 2015 a crack formed on the same hanging glacier massif, which continued to grow until January 2016. This was followed by several ice-rock falls, the largest of which happened in the period April 10 – June 19, 2016. In total, all collapses of 2016 were comparable in volume to the collapse of 2023. By this time, the hanging glacier had been fully restored and occupied the same position it had in 2015. We next investigated a part of the slope of the Dzhangitau Zapadnaya mountain (5059 m a.s.l.) on the Bezengi Wall massif, on the hanging glacier of which the formation of a crack with a length of about 400 m was revealed in the summer of 2023. By September, the crack width had increased to 40 m. Leyer on, the crack became stable. But in the period of September ‒ December a certain surge of the glacier at the foot of Dzhangitau Zapadnaya mountain was revealed at a speed of about 1 m per day with the formation of a prominent frontal bank overlying the Bezengi Glacier. This research confirmed the activation of the landslide processes in the high-altitude zone and showed the need for continuous monitoring based on the analysis of satellite images for the timely revealing areas with a potential threat of any ice-rock falls and warning about the danger
Evolution of lakes near the Dzhikiugankez glacier (Northern Elbrus area) in 1957–2020 with consideration of underground flow channels
Get PDFEvolution of lakes near the Dzhikiugankez Glacier in the north of Elbrus for the period of 1957–2020 was studied using a comparative interpretation of aerial and satellite images as well as aerial and ground surveys in 2007–2018. Within this period the area of the Dzhikiugankez Glacier (43,35 N, 42,53 E) decreased by 8.2 km2. On the territory previously occupied by the glacier and close to it, 19 lakes appeared at different times, which dynamically developed and broke through. The lakes cover the area of 0.43 km2, that equals to 5.21% of the total icefree area. The average area of the lakes is 26.6 thousand m2. The maximum (the lake East Birdzhaly) is 89 thousand m2. In total there were six lakes larger than 25 thousand m2. They are concentrated in depressions on the surface of an ancient lava flow dammed by glaciers, dead ices and moraine lines. At a certain stage in the evolution of lakes, water from them penetrated through these barriers and, thus, formed subglacial and underground drainage channels. In 2013, during helicopter flights, an underground drainage channel with a length of more than 80 m was detected in the moraine line around the Lake «Podkova». The survey made possible to determine decreasing in the lake level by 2 m, and the accumulation of water with a volume of up to 48 thousand m3 in the cavities of the moraine massif, until it reaches the outer slope. The accumulated volume of water interflowed through the underground channel gradually, but despite the pot-holes on its bottom, no mudflow happened in the valley. Although in another case, the formation of an underground drainage channel from the Severnoye Chungurchat Lake was accompanied by a lake breakthrough and a mudflow. Other characteristic features of the evolution of lakes and changes in the direction of drainage from glaciers are also analyzed in the paper
DETERMINATION OF THE OPTIMAL DISTRIBUTION OF SUPPORTS IN THE FLOOR SLABS OF IN-DUSTRIAL BUILDINGS USING STOCHASTIC METHODS
Get PDFAbstract. Aim. The purpose of the study is to determine the optimal location of supports used in the floor slab of an industrial building.Method. In order to determine the optimal arrangement of the columns, a Monte Carlo algorithm was used in combination with the finite element method. The calculation was carried out on the basis of the theory of elastic thin plates.Results. The article presents a solution to the problem of determining the optimal location of a given number of point-supports of a floor slab n from the condition of minimum objective function. For the objective function, the maximum deflection of the slab, the potential energy of deformation and the flow rate of reinforcement were selected as variables. The selection of reinforcement was carried out in accordance with current generally-accepted standards for the design of reinforced concrete structures. The calcu-lations were performed using a program developed by the authors in the MATLAB computing environment. The results are given for n = 3,4,5. The algorithm, which has been modified for a large num-ber of supports n, is presented alongside a comparison of the basic and modified algorithm with n = 25. The possibility of a significant reduction in plate deformations with an irregular arrangement of supports compared to a regular distribution is shown.Conclusion. A method is proposed for finding the rational locations of point supports for a floor slab for a given quantity from the condition of min-imum deflection, potential strain energy and consumption of reinforcement materials based on the Monte Carlo method. This technique is suitable for arbitrary slab configurations and arbitrary loads. A modification of the algorithm is presented that is suitable for a large number of supports. The test example shows that the maximum deflection can be reduced by 42% when using an irregular support configuration compared to regular column spacing. In the considered examples, the position of all the supports was previously considered unknown, but the developed algorithm easily allows for stationary supports, whose position does not change
ТРАНЗИТ И АККУМУЛЯЦИЯ СЕЛЕЙ РЕКИ ГЕРХОЖАН-СУ НА УЧАСТКЕ СЕЛЕПРОПУСКНОГО КАНАЛА В ГОРОДЕ ТЫРНЫАУЗ
Get PDFDebris flows of the Gerkhozhan-Su River are distinguished by high activity and danger and pose a threat Tyrnyauz city (Central Caucasus) and its inhabitants. To protect the Tyrnyauz city from debris flows of the Gerkhozhan-Su River a debris flow check channel was built in the early 1960s. It was partially destroyed after the disastrous debris flows of 1999–2000 and then restored. Subsequent debris flows (2011 and 2017), passing through the channel, left traces on its walls and also deposited debris material at the bottom of the channel, gradually filling it. Specific characteristics of the transit and accumulation of debris flows at the section of debris flow check channel were determined using route surveys and video-footage analysis of the Gerkhozhan-Su River debris flows. The dynamics of debris flows on August 14–15, 2017 at the section of debris flow check channel was recorded on numerous videos. The photo and video information was processed in the ArcGIS software – scaled multi-temporal photos taken before and after debris flows were linked and combined with video frames. The debris flow waves passage velocity was determined by means of video materials with the measurement of distances on a high-resolution satellite image. Debris flows in 2017 were sweeping through the channel at a velocity of 9–12 m/s. Sections of temporal debris flow mass deposit with the preserved structure of debris flow were revealed. Subsequent debris flow waves passed over and carried the deposited debris flow mass down from the channel. It is shown that the determination of the debris flow cross-section from debris flow traces on the walls of the channel can lead to overstatement in the values of the calculated debris flow discharges. It is revealed that after each debris flow at the bottom of the channel, the thickness of the debris flow deposits increased by 1.5 m on the area of the former pedestrian bridge. Protection role was noted of debris flow check channel and the need for its timely cleaning from deposits to ensure the debris flow safety of the Tyrnyauz CityСелевые потоки реки Герхожан-Су отличаются высокой активностью и опасностью и представляют угрозу городу Тырныаузу (Центральный Кавказ) и его жителям. Для защиты города Тырныауза от селей реки Герхожан-Су в начале 1960-х годов был построен селепропускной канал, который частично разрушился после катастрофических селей 1999–2000 годов и затем был восстановлен. Последующие селевые потоки (2011 и 2017 годов), проходя транзитом, оставляли следы на стенках канала, а также откладывали обломочный материал на дне канала, постепенно заполняя его. На основе данных маршрутных обследований и видеонаблюдений за селевыми потоками реки Герхожан-Су определены особенности транзита и аккумуляции селей на участке селепропускного канала. Динамика селевых потоков, прошедших 14–15 августа 2017 года, на участке селепропускного канала зафиксирована многочисленными видеороликами. Фото- и видеоинформация обрабатывалась в программе ArcGIS – привязывались разновременные масштабированные фотографии до и после прохождения селей и совмещались с кадрами видеосъёмки. По материалам видеороликов определялась скорость прохождения селевых волн с измерением расстояний на космоснимке высокого разрешения. Селевые потоки 2017 года проносились по каналу со скоростью 9–12 м/с. Выявлены участки временного отложения селевой массы с сохранившейся структурой селевого потока. Поверх отложенной селевой массы проходили последующие волны селевого потока, которые в итоге выносили временно отложенную массу вниз из канала. Показано, что определение поперечного сечения селевого потока по следам селей на стенках канала может приводить к завышенным величинам рассчитанных расходов селевых потоков. Выявлено, что после каждого селевого потока мощность селевых отложений на дне канала на участке бывшего пешеходного моста увеличивалась на 1,5 м. Отмечена важная селезащитная роль селепропускного канала и необходимость своевременной его очистки от селевых отложений для обеспечения противоселевой безопасности города Тырныауз.
Докукин М.Д., Савернюк Е.А., Богаченко Е.М., Иванов Г.И. Сель 3 августа 2011 г. в бассейне реки Герхожан-Су: причины, динамика и возможные последствия // Геориск. 2012. № 2. С. 48–56.
Докукин М.Д., Беккиев М.Ю., Богаченко Е.М., Калов Р.Х., Савернюк Е.А., Хаджиев М.М. Селевые потоки 14–15 августа 2017 г. в бассейне р. Герхожан-Су (Центральный Кавказ): условия и причины формирования, динамика, последствия // Геориск. 2018. Т. 12. № 3. С. 82–94.
Запорожченко Э.В. Сели бассейна р. Герхожан-Су: история проявления, условия формирования, энергетические характеристики // Сборник научных трудов ОАО «Севкавгипроводхоз». 2002. Вып. 15. С. 80–148.
Сейнова И.Б., Золотарев Е.А. Ледники и сели Приэльбрусья: (Эволюция оледенения и селевой активности). М.: Научный мир, 2001. 203 с.
Соколова Д.П., Куровская В.А., Осташов А.А., Казаков Н.А. Оценка динамических характеристик селевого потока по видеоматериалам // Гидросфера. Опасные процессы и явления. 2019. Т. 1. Вып. 1. С. 31–51. DOI: 10.34753/HS.2019.1.1.003.
Черноморец С.С. Селевые очаги до и после катастроф. М.: Научный мир, 2005. 180
Активизация обвалов на Центральном Кавказе и их влияние на динамику ледников и селевые процессы
Get PDFWe analyzed multi-time satellite images of the Central Caucasus glacial zone and interpreted more than thirty rock avalanche events in the 21st century with a total damage area of more than 25 km2 (including the collapse zone of the Kolka Glacier disaster). The highest rock and rock-ice avalanche activity is detected in the section of The Greater Caucasus range (northern and southern slopes) with a length of about 20 km between the Bashkara and Kulaktau peaks (16 rock avalanches) and in the section of the Kazbek-Dzhimaray Massif (series of rock avalanches to the surface of Kolka, Suatisi and Devdoraki glaciers). The feature of the rock and ice-rock avalanches is the large runout distance. For 12 events (about 40%) the distance was more than 2000 m. One ice-rock avalanche from the Mount Kazbek (excluding the Kolka Glacier disaster in 2002) reached the runout distance more than 10 km. In some areas, the rock avalanches occurred several times. In particular, a large number of avalanches were in the cirque of the Kolka Glacier; the last of them at the end of 2019. Thrice шт each case, rock avalanches originated from Mount Bashkara, in the cirques of the Murkvam Glacier, the East Shtulu Glacier, and the Devdoraki Glacier. Ice and rock avalanches were the initial stage of the complex process of the Kolka Glacier disaster and following catastrophic glacial debris flow in the Genaldon/Gizeldon River valley in 2002. Also, they were causes of glacier surges, formation of dammed lakes, and debris flows. As a result of the collapse of the hanging glacier and bedrock, the former right tributary of the Kolka Glacier surged to 200 m in 2006. Ice-rock avalanche from Mount Kazbek in 2014 load up the former right tributary of the Devdoraki Glacier and caused its advancing in 2015–2019, at a distance of more than 400 m. The avalanches caused catastrophic debris flows in the Amilishka/Kabakhi River valley in 2014, the Mestiachala River valley in 2019. Rock avalanches can cause outbursts of lakes and debris flows. Two dammed lakes formed as a result of the rock avalanche from the cirque above the Seri Glacier in the Tviberi River valley of the in May 2016. The lakes (total area was more than 0.05 km2) have outburst at the end of August 2017 after heavy rains. Rock avalanches of the 20th century led to an abrupt deceleration in the retreat of the Yusengi, Bartuytsete, East Shtulu and Mosota glaciers. The formation of rock avalanches in the 21st century took place at high altitudes (an average of about 3900 m). Possibly, the reason was associated with an increase of the «0» isotherm and of the high border of the zone of intense frost weathering due to climate warming. Some rock avalanches in the section of the Kazbek-Dzhimarai Massif have been caused by endogenous factors (seismicity and volcanism).На основе анализа разновременных космических снимков приведены данные о 32 обвалах в ледниковой зоне Центрального Кавказа в ХХI в. Половина из них сосредоточена на участке северного и южного склонов Главного Кавказского хребта восточнее горы Башкара. Отмечена высокая активность обвалов в 2019 г., показано влияние обвалов на динамику ледников и селевые процессы
Эволюция озёр у ледника Джикиуганкез (Северное Приэльбрусье) в 1957–2020 гг. с учётом подземных каналов стока
Get PDFEvolution of lakes near the Dzhikiugankez Glacier in the north of Elbrus for the period of 1957–2020 was studied using a comparative interpretation of aerial and satellite images as well as aerial and ground surveys in 2007–2018. Within this period the area of the Dzhikiugankez Glacier (43,35 N, 42,53 E) decreased by 8.2 km2. On the territory previously occupied by the glacier and close to it, 19 lakes appeared at different times, which dynamically developed and broke through. The lakes cover the area of 0.43 km2, that equals to 5.21% of the total icefree area. The average area of the lakes is 26.6 thousand m2. The maximum (the lake East Birdzhaly) is 89 thousand m2. In total there were six lakes larger than 25 thousand m2. They are concentrated in depressions on the surface of an ancient lava flow dammed by glaciers, dead ices and moraine lines. At a certain stage in the evolution of lakes, water from them penetrated through these barriers and, thus, formed subglacial and underground drainage channels. In 2013, during helicopter flights, an underground drainage channel with a length of more than 80 m was detected in the moraine line around the Lake «Podkova». The survey made possible to determine decreasing in the lake level by 2 m, and the accumulation of water with a volume of up to 48 thousand m3 in the cavities of the moraine massif, until it reaches the outer slope. The accumulated volume of water interflowed through the underground channel gradually, but despite the pot-holes on its bottom, no mudflow happened in the valley. Although in another case, the formation of an underground drainage channel from the Severnoye Chungurchat Lake was accompanied by a lake breakthrough and a mudflow. Other characteristic features of the evolution of lakes and changes in the direction of drainage from glaciers are also analyzed in the paper.По данным дешифрирования аэрофотоснимков и космических снимков за 1957–2020 гг., а также полевых наблюдений и вертолётных облётов определены особенности эволюции озёр у ледника Джикиуганкез и механизмы их прорыва, в том числе по подземным каналам. На примере озёр Подкова, Северное Чунгурчат и Балык Южное показано, что формирование подземных каналов стока не обязательно приводит к сходу селевых потоков, однако даже небольшие озёра могут быть очагами значительных селей
