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The authors discuss applicability of phase characteristics of surface waves in monitoring of underground openings and tunnels. The mathematical model of surface wave propagation along extended cavities is presented. The properties of the numerical solutions obtained using the model are analyzed, including the amplitude and frequency characteristics, and the phase and group velocities of the waves. It is possible to recover elastic properties of a medium using the dispersion curves of the phase velocities. The data of numerical modeling of surface wave propagation along cavities of different geometry using the method of finite spectral elements are presented. The calculated results of the axisymmetrical and three-dimensional problems of surface wave propagation along cavities are studied.

Bischofite rock samples from a well at the Vologda underground gas storage are subjected to rheological tests. The time curves of deformation are plotted at different axial and lateral stresses. A viscoelastic phenomenological model is proposed, and the equation to describe these dependences is obtained. Being developed and algorithmically implemented, the experimental data interpretation procedure allows determining rheological characteristics of test rocks at different stress ratios. It is found that rheological properties of bischofite weakly depend on depth.

The implementation stages of ground laser scanning of an open pit field and the obtained data processing in Maptek I-Site Studio are discussed as a case-study of Kentobe open pit mine of iron ore. The procedure of a digital geological-geomechanical model is described; the framework is a set of spatial points obtained from the laser scanning. The model enables a detailed study of geological structure of the pitwall rock mass, with regard to the structure and tectonics, as well as the physical and mechanical properties of rocks. Using the developed model, the authors estimated the pitwall stability and substantiated safe slope parameters for deeper mining.

To predict uniaxial compressive strength using the indirect techniques of the Schmidt hammer rebound number (N) and Point Load Index (PLI), it is required to have valid empirical equations based on rock types. This study is an attempt to address this issue by developing a model that is valid for various rock types. Three models, i.e. linear, power and quadratic, were tested on each rock type (sedimentary, ingenious and metamorphic). The highest correlation was achieved by the quadratic model. The generalized model showed the lowest correlation as against the individual models.

The authors estimate stress state in the support system and in rocks nearby a roadway driven in unstable rock mass and when the voids and cavities in the roadway roof are filled with hardening foam. The calculation includes an assumption that the support system, rocks and the hardening foam deform elastically. The stress distribution in the support system is determined at different heights of the rock cavity in the roof rocks in the roadway and at different initial stress state of rocks. The zones of potentially hazardous stress concentration in the support system are identified.

The article describes the lab-scale testing data on acoustic and seismic emission generated in hydraulic fracturing of a cement block under volumetric loading by nonequal stresses. The connection of the acoustic and seismic emission with the rate of injection of power fluid and the change in the fluid pressure in the course of the fracture initiation, growth and arrest is demonstrated. The authors recommend on improvement of receiving equipment and on using the research findings in the hydraulic fracturing control.

This study focuses on an impact wave generated in a uniaxially compressed granite sample by a pendulum hammer in the direction transversal to compression. The pressure was varied from zero to a pre-destructive value. Microcracking during impacts was recorded using the method of acoustic emission (AE). The energy distribution in the time series of AE pulses followed an exponential law both in the unloaded and in the statically loaded samples. The first impacts induced local damage with a splash in AE from small cracks which, under subsequent impacts, coalesced and initiated redistribution of larger microdamages. In generation of an impact wave in a sample under pre-limiting compression, the surface of the induced main crack exceeds the area of the local damages by a few orders of magnitude, which is typical of the trigger effects which lead to large-scale fractures under external impacts at a safe-density energy.

Methods for calculating vertical channel deformations based on hydrometric observations at the network of Roshydromet posts are considered. A method based on the relationship between water flow rates and levels is evaluated. It is concluded that the use of this method causes a number of serious difficulties and contradictions which do not allow its use in mass calculations. A method for assessing deformations based on using the lowest elevations of the channel is proposed. These marks are calculated from measurements of the channel simultaneously with the regular determination of water flow rates. The method was tested at 41 stations with a catchment area from 116 to 186 000 km² in the basins of the Angara, Upper Lena, Vitim, and Lake Baikal. The data were used for the entire observation period, with a duration of 35 to 80 years from 1943 to 2017. Vertical deformations are noted at all posts without exception. Their characteristic amplitude for the observation period is 50-150 cm. At one quarter of the posts, this value reaches 150-300 cm. The trend of deformations is multidirectional. In 41 and 39 % of cases, scouring and alluvium were observed, respectively. At the other posts, the trend is not pronounced. The calculations and the examples of their interpretation show the ability of the approach described to reveal various features of the process of vertical deformation of river beds. In particular, on its basis, it is concluded that there is a relationship between deformations and water flow rates when the same water flow rate on small rivers can produce tens of times more work of deformation of the channel bed than on large rivers.

This research has identified the landscapes in Chiapas State (Mexico) with the best natural conditions by using the theoretical-methodological principles of complex physical geography. To achieve this goal, the biodiversity was assessed by calculating the number of vascular plant species for each landscape unit and correlated with the results of previous research regarding landscape diversity and anthropization of vegetation cover. The results indicate that the highest levels of biodiversity correspond to the predominant and recurring landscapes. These geographical relationships indicate the influence of the geomorphological component on the distribution of biodiversity, which was quantitatively validated via two statistical correlations. It was found that the complexes of summits, hillslopes, and gullies in mountain landscapes of tectonic-karstic, tectonic-accumulative and tectonic-intrusive origin, in temperate, semi-warm humid to subhumid, warm humid, and warm subhumid climates, located in the physical-geographical regions of Lacandona Mountains, Southern Mountains of Chiapas, and Western Mountains of Chiapas, all have the most preserved physical-geographical landscapes. In recent years, however, geocomplexes have been impacted by society, which is particularly evident in the Northern Mountains of the Chiapas region. The results of this research are an important contribution to the land-use planning processes because they make it possible to objectively establish environmental policies in Chiapas. For instance, this research provides the geographic basis for modifying or promoting new natural protected areas.

A brief review of research and organizational and teaching activities of a famous geographer Yuri Petrovich Mikhailov, whose creative life activity is connected with the V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences (1961-2010). The fields of his scientific interests are considered: theory and methods of socio-economic geography, problems of nature management, peculiarities of the development of the domestic agrarian sector and rural areas, and integrated development of the taiga territories of Russia. A special place in Yu.P. Mikhailov’s scientific work is occupied by the issues related to the study, assessment and mapping of natural resources as well as geographical expert examination of major projects, the study of processes associated with the transformation of the habitat and the prediction of the consequences, and the protection and reproduction of the natural environment. It is explicitly pointed out that the wishers and message of Yu.P. Mikhailov’s scientific work to future generations of geographers imply their commitment to a system approach in geography. Presented is an extensive geography covered by the scientist’s research: Leningrad oblast, Crimea (subjects-polygons of his first field work) and, later, the territories of Siberia and the Far East. Qualitative and quantitative parameters of his publication activity and achievements in research and organizational activities are reflected. It is emphasized that the works of Yuri Petrovich Mikhaylov have an enduring theoretical and methodological, constructive and ideological significance.