EXPECTED SEISMIC INTENSITY ASSESSMENT TAKING INTO ACCOUNT LOCAL TOPOGRAPHY SITE EFFECT

ABSTRACT: The analysis of seismic codes of different countries shows accounting of seismic properties of soils caused mainly by their physical and mechanical properties but effect of the topography on site effect is not even considered. Exception is the Building Codes of France. The paper presents the results of experimental investigations of the influence of topographic features on the formation of the effect of strong earthquakes. Examples of amplification of seismic effect due to relief features are shown in the form of field, laboratory and numerical (mathematical modelling) investigations. It is defined that not only slope angle but also height of observation point significantly influences on site effect. It is shown that the intensity of the earthquake in mountainous areas is determined not only by the slope angle value, but also the specific location of the site in the hierarchy of the rock massif. Obtained instrumental data analysis showed that the influence of the relief on the seismic effect of the earthquakes can be most completely accounted by the parameter R, that is the product of the slope angle and the height. It has been defined that the intensity increment can be changed regardless of the constituent rock types from 0 to 1.5 points. It is found that the vibration amplitude varies considerably with the relief and this dependence is different for the displacements, velocities and accelerations.

Soils’ classification according to their seismic properties in Building Codes of various countries

The article presents the results of Building Codes’ analysis in different countries of the world in terms of taking into account the seismic properties of soils when calculating buildings and structures for seismic effects. The main indicators of the soils’ seismic properties are highlighted, their analysis is carried out from the point of view of the possibility and necessity of taking them into account in the future Building Codes of Georgia. The basis for the soils’ classification according to their seismic properties has been developed. The conclusion about the validity of using the new Building Codes of Russia and the Building Codes of the United Europe (Eurocode-8) is made as the basis for future Russian standards in terms of taking into account the seismic properties of soils by their seismic properties. The paper indicates that the new Building Codes in Russia will be developed based on the Building Codes of the former USSR. The main provisions of the standards have been tested in practice and, if the construction is in accordance with them, buildings and structures withstand seismic effects well. These Regulations do not contradict the Eurocode-8 Standards, which are undoubtedly more progressive and can be taken as a basis for future Building Codes in Russia. In conclusion, the main criteria for the soils’ classification according to their seismic properties are given

SPECTRAL CHARACTERISTICS OF SEISMIC WAVES AT STRONG GROUND MOTIONS

ABSTRACT: Introduction of the value of the weight-average period of ground vibrations significantly improves the differentiation quality of various types of soils. The dependence of the spectral composition of the seismic waves on power, physical and mechanical properties of soils that compound a ground stratum and hydrogeological conditions are considered. On the basis of data analysis a conclusion about high usefulness of powerful pulsed and vibration artificial nonexplosive sources for seismic microzonation is made. A particular attention was paid to the investigation of the absorption indexes of seismic energy in different types of soil. It is shown that the use of the extended type of soil indexes, in particular, to include the standard spectral characteristics can significantly improve the accuracy and reliability of the establishment of engineering and geological cross-section of a ground stratum and its hydrogeological conditions

Allocation of zones with different responses of ground movement individual indicators to standard seismic impact

The paper presents the results of calculating the vibrations of the soil strata using the ZOND- (linear) program. Accelerograms of earthquakes recorded in Tbilisi (12/14/2000) and Athens (09/7/1999) on rocky soils were set as a standard seismic action in the bedrock of a loose soil layer. The maximum amplitudes of records and the soil vibrations real spectrum areas were considered as the soil movement indicators. The ratios of the presented indicators to the corresponding values of the initial values were calculated. The results obtained in the form of the indicators’ ratios for the soil movement in the areas under consideration were used to differentiate soils by their response to standard seismic action. Differentiation of soils in the corresponding areas was carried out in three groups according to the value of this ratio. The zones of soil reaction to the standard seismic action were identified. The sites of the third group are tentatively assigned to the most dangerous areas in terms of seismicity. Due to the fact that the calculations were based on a linear-elastic representation of the soils’ behavior, typical for small deformations, the data obtained are preliminary methodological in nature and will be refined in the future

Eco-Geophysical and Geoecological Factors in Assessing the State of the Geological Environment Based on the Analysis of Spatial Databases of the Territory of the Republic of North Ossetia–Alania

The article considers the main sources of pollutionin the territory of the Republic of North Ossetia–Alania. A study of environmental geophysical factors in the city of Vladikavkaz was carried out at 126 points; indicators of noise pollution, electric fields and the level of gamma radiation were measured. A geoaccumulation index of heavy metals in soils and indices of carcinogenic and non-carcinogenic risks were calculated and corresponding maps were constructed. The obtained data supporting a high level of carcinogenic risk are consistent with a high level of cancer morbidity in the city, which indicates a close relationship between morbidity and the carcinogenic risk index. It has been determined that emissions from road transport are greater by an order of magnitude than stationary sources emissions, while there is a steady trend towards an increase in air pollution as a result of the increasing negative impact of motor vehicle emissions. It has been established that the most hazardous way for heavy metals to enter the human body from the soil is by inhalation. It has been determined that in areas where environmental pollution with heavy metals is higher, cancer morbidity is also higher

Detailing the Pore Structure of Productive Intervals of Oil Wells Using the Color 3D Imaging

The article describes an approach to expanding the methodology for applying hydraulic fracturing in oil fields by adding the possibilities of 3D modeling with color imaging of the pore structure of the productive intervals of wells. As an applied example, the geological and geophysical section of the productive level of one of the wells of the Moscudinskoye oil field, with known data on the integrated interpretation of the results of well-logging and microcomputer tomography, was chosen. According to well-logging data, the productive reservoir in the analyzed section of the section is characterized by a high degree of heterogeneity. Tomographic studies of a full-size core made it possible to identify four lithotypes here with different pore structure features. Accounting for the identified reservoir heterogeneity, as well as data on the thickness and other characteristics of reservoir properties of individual lithotypes that make up the section, made it possible to significantly increase the detail of the final geological model of the wellbore section. A distinctive feature of this final geological model is the use of the method of enlargement of the initial data array by adding intermediate values that were calculated theoretically. The visibility of the final geological model of the borehole walls is provided by color 3D imaging of the calculated data of the enlarged massif and makes it possible to judge the presence of areas with good and weak fluid conductivity on the lateral surface of the borehole walls. According to this model, intrastratal transverse and longitudinal fluid-conducting “corridors” are observed in the circumwell zone that determine the hydro-dynamic movements of natural and artificial fluids in the space of productive reservoirs

Anthropogenic landslide geodetic monitoring

The first results of monitoring the slow dynamics of an anthropogenic landslide located in the mountainous part of the Republic of North Ossetia-Alania are presented in the article. Landslide motion measurements were performed using tacheometric surveying and the GPS/GLONASS global positioning system. The article considers the selection of sites for installation the basic network points for landslides monitoring

Pollution of urbanized territories by motor transport using the example of the Republic of North Ossetia - Alani

According to numerous studies, even with a relatively low level of exposure to adverse environmental factors, risk of health deterioration may occur. Both the amount of harmful emissions and their chemical composition directly affect the level of air pollution. The article considers the issues of environmental pollution of an urbanized area by automobile exhausts. The most polluted city is Vladikavkaz that is the capital of the Republic. There the main stationary sources of pollution are located and the largest number of vehicles is concentrated. The dynamics of increasing the number of vehicles in the city of Vladikavkaz over the past 10 years and a corresponding increase in harmful emissions from combustion products are shown. For the same period of time, the amount of emissions of harmful substances into the atmosphere from stationary sources has been considered in order to compare their contribution to total pollution compared to road transport. Based on the explorations, it is shown that the main source of pollution in terms of emissions in the Republic of North Ossetia-Alania is road transport. The number of vehicles is increasing year after year, amid a decrease in total emissions of pollutants from stationary sources

Natural endogenous factors of geoecological transformation of the mountain part of North Ossetia

Geoecological transformation of the biocenosis habitat is an evolutionary process, predetermined by the interaction of the lithosphere with the hydrosphere, atmosphere and the solar system as a whole, under the condition of anthropogenic impact absence. Geoecological transformation occurs under the influence of many natural factors of an endogenous and exogenous nature, the effects of which in the mountainous areas are especially intensive and damageable, due to the sharp and intense exposure forms of exogenous factors of the erosive destruction, the presence of a large gravitational potential for a spatial removal of the destroyed material, poor protection of the bedrocks by biogeocenosis, low strength of terrigenous rocks, etc. The main factors of the intensive geoecological transformation of the mountain landscape are endogenous geodynamic processes. The Greater Caucasus, as the geosynclinal region of young Alpine orogenesis, is characterized by the active deep geodynamics, the focal zones of which can be activated in time and migrate in the lithosphere, as evidenced by the interchange of the periods of seismic activity and relative passivity of deep geodynamic processes (fault tectonics, seismicity and magmatic manifestations). A high density of the tectonic faults contributes to the weakening of rock strength in the zone of a faulting crop out due to jointing and claying along the friction planes