scholarly journals Modeling of the stress-strain state in the earthquake epicenter area (Kumamoto Earthquake, Japan), 16.04.2016 M 7.3

Author(s):  
V. N. Morozov ◽  
A. I. Manevich

On the 16th of April, 2016, a strong earthquake with M 7,3 occurred in the Kumamoto prefecture (Kyushu, Japan). This earthquake is the strongest in the last 30 years in this area. For a day before the main shock, two foreshocks with M 6,4 were registered. For seven days after the main shock, aftershocks activity spread to the north-east and south-west, most of the hypocentres of the aftershocks with M 6,4 were localized within the seismogenic layer in the depth interval from 5 to 10 km. The authors have modeled a stress-strain state (SSS) of the epicentral area be fore the earthquake and after it (after the formation of the main fault). For this purpose, a software package is used, that allows 2-D formulation (plane strain condition), for modeling SSS block heterogeneous geological environment, disrupted by a system of tectonic faults. The faults are modeled in the form of extended zones of the dispersed geomaterial, which elastic modulus are significantly lower than the elastic modulus of the environmental media. A structural-tectonic scheme of the Kumamoto earthquake area is used. An analysis of the results of SSS modeling has been done for the area 30x40 km before and after the earthquake. It is shown that the area and magnitude of the stress intensity in anomalous zones are the predictive signs of the location and intensity of a possible strong crustal earthquake, and the vector of the rapid decrease in the potential energy of deformation could be a guide for the most probable direction of tectonic rupture during a crustal earthquake. The results received can be useful in a deterministic approach to seismic hazard assessment and carrying out the geophysical observations focused on the forecast of the strong crustal earthquakes in the continental areas.

Geotectonics ◽  
2018 ◽  
Vol 52 (5) ◽  
pp. 578-588 ◽  
Author(s):  
V. N. Morozov ◽  
V. I. Kaftan ◽  
V. N. Tatarinov ◽  
I. Yu. Kolesnikov ◽  
A. I. Manevich ◽  
...  

Author(s):  
М.Г. Попов ◽  
О.Г. Попова

При оценке сейсмической и экологической опасности напряженно- деформированное состояние геологической среды является важнейшей геодинамической характеристи- кой районов гидравлических (ГЭС) и атомных (АЭС) электростанций, предприятий ядерного топливного цикла (ЯТЦ), химической промышленности, стратегически важных объектов, густонаселенных мегаполи- сов и курортных районов. Цель работы. В статье обобщены полученные результаты значений геодинами- ческих показателей напряженно-деформированного состояния среды для разных по своей тектонической активности районов РФ. Методы исследования. Локальный сейсмо-экологический мониторинг (ЛСЭМ) позволяет оценивать значения геодинамических показателей анизотропности γ и напряженного состо- яния среды S по энергии обменных волн PS от далеких землетрясений. Эти показатели характеризуют состояние среды во времени и в пространстве. Наблюдения во всех регионах проводились с помощью локальной сети (площадная расстановка) трех компонентными станциями типа Дельта-Геон. Результа- ты. Приведены основные закономерности изменения значений геодинамических показателей для одного интервала глубин: диапазон значений γ и S в районах разной тектонической активности, цикличность их изменений и влияние на них внешних природных факторов (Луны, Солнца, солнечной активности и т. д.). По результатам самых длительных наблюдений ЛСЭМ (1995-2006г) на Кавминводском полигоне (сейс- моопасный Минераловодский регион) получены 3‑х мерные модели показателя анизотропности γ и про- ведена оценка показателей напряженного состояния S на разных уровнях глубин. Показано, что характер распределения показателя анизотропности γ непрерывно изменяется по глубине, латерали и во времени. Выявлена цикличность в изменении показателя S во времени на всех глубинах. Создание таких 3‑х мер- ных моделей и для других особо важных объектов позволит дать более объективную картину напряженно- деформированного состояния геологической среды, что требует, однако, более длительных наблюдений When assessing seismic and environmental hazards, the stress-strain state of the geological environment is the most important geodynamic characteristic of the areas of hydraulic (HPP) and nuclear (NPP) power plants, nuclear fuel cycle (NFC) enterprises, the chemical industry, strategically important objects, densely populated megacities and resort areas. Aim. The article summarizes the results obtained for the values of the geodynamic indicators of stress-strain state of the medium for regions of the Russian Federation that are different in their tectonic activity. Methods. Local seismic-ecological monitoring (LSEM) allows us to assess the values of the geodynamic indicators of anisotropy and the stress state of the medium S from the energy of the exchange waves PS from distant earthquakes. These indicators characterize the state of the environment in time and space. Observations in all regions were carried out using a local network (areal arrangement) of three component stations of the Delta-Geon type. Results. The basic laws of changing the values of geodynamic indicators for one depth interval are presented: the range of γ and S values in regions of different tectonic activity, the cyclical nature of their changes, and the influence of external natural factors (the Moon, the Sun, solar activity, etc.) on them. According to the results of the longest observations of the LSEM (1995-2006) at the Kavminvodsky test site (seismic hazardous Mineralovodsk region), 3‑dimensional models of the anisotropy index were obtained and stress state indicators S were evaluated at different depth levels. It is shown that the nature of the distribution of the anisotropy index continuously varies in depth, laterally, and in time. The cyclical nature of the change in S over time at all depths is revealed. The creation of such 3D models for other particularly important objects will allow us to give a more objective picture of the stress-strain state of the geological environment, which requires, however, longer observations


2019 ◽  
Vol 8 (5) ◽  
pp. 205-212
Author(s):  
Masato TAYAMOTO ◽  
Shinji FUKUMOTO ◽  
Michiya MATSUSHIMA ◽  
Kozo FUJIMOTO

Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.


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