"Вестник МГСУ"

The problems of hydraulic engineering require expansion of the scale of research on destructive coastal processes of water bodies located on the territory of the permafrost. Subject: of research in this article are the slopes of the rivers located in the zone of frozen rocks, and the main possible processes on them, occurring under the influence of various seasonal factors. The aim of this work is to study the thermo erosion slope processes of permafrost with allowance for hydromechanical and thermodynamic factors and the development of the main characteristics of these processes, as well as the construction of a single model that allows estimating and predicting the effect of seasonal conditions (including spring snowmelt and exposure to solar radiation) on possible destructive coastal processes at water bodies located on the territory of the permafrost zone. Materials and methods: theoretical analysis and generalization of known achievements in the field of hydrology and glaciology, the theory of slope processes, sediment transport, mechanics of frozen soils, and filtration. As a factual material, the data of laboratory experiments carried out in the PFUR hydraulic laboratory on a facility that allows varying rain currents of varying intensity, while measuring both the rate and number of infiltration flows, and the amount of side flow in the case of frozen or partially thawed soil, that were used as factual material. A various soil structure was modeled by freezing or introducing ice interlayers. Such studies in the laboratory were conducted for the first time. Results and conclusions: a method for predicting thermo-erosion is proposed taking into account the effect of seasonal conditions on permafrost. The influence of the direction of the coastal incline on the rate of thawing of soils under the influence of solar radiation is studied. The influence of ultraviolet rays on snow melting is different from the influence of infrared rays, since short waves (UV) penetrate deep into opaque substances and are transformed into heat fluxes within the snow layer. Cloudiness is a deterrent only for the IR portion of the spectrum. It has been shown experimentally that the dependence of the erosion of solid matter on the slope angle (other things being equal) will have a exponent (4/3) form. Thawing and erosion of frozen water bodies are proportional to the square root of time. The linear coefficient depends on the nature of the rock, ice content, ambient temperature and flow temperature. On the basis of the results obtained, it is possible to give practical recommendations for preventing and reducing the negative impact of the destructive processes under investigation, which is especially important for those areas where intensive hydrotechnical construction is being carried out.

The authors consider varied engineering actions aimed at the protection of pipelines from developing erosion processes with a focus on the conditions of northern regions. Engineering solutions, considered in the article, include prevention of erosion processes along pipelines, protection from suffusion, protection of extended areas having the limit value of the slope angle, and actions aimed at the drainage of areas along pipelines. Prevention of erosion processes along pipelines consists in the restoration of the fertile layer using biological methods, as well as the volumetric soil reinforcement using geological grids. Prevention of suffusion processes consists in the employment of various types of suffusion shields accompanied by the application of geotextile. Berms are constructed as suffusion prevention actions in extended areas having a limit value of the slope angle. This action is used to reduce the water flow energy of drainage ditches and trays along the pipeline. The authors believe that a complete geotechnical monitoring network must be designed and developed to monitor the condition of pipelines and foundation soils.

In this article we propose a classification for the masses of rock and soil, located in the bases of the buildings in permafrost zone. Classifications are made for masses consisting entirely of rock and soil with negative temperature, as well as for masses, including thawed soils and rocks. Updated in 2011 the Russian All-Union State Standard«Soil», which came into force in 2013, includes a classification of frozen soils, which are distinguished in a separate class. This is one of the differences of our inter-state standard, issued by the Eurasian Council for standardization, Metrology and certification, from the international English-language normative document (ISO). It is caused by the fact that on the territory of the European Union there is no permafrost soil, and only soils and rocks are discussed. In contrast, on the territory of Russia permafrost soil is widely distributed, in particular in the areas of extraction of exported raw materials. Permafrost is causing a significant, ongoing difficulties of construction and operation of buildings.The classification of soils in the Russian All-Union State Standard «Soil» and here is based on the type of physical and physico-chemical bonds between the particles in a soil. In frozen soils there are specific unstable bonds, due to the presence of ice. This fact calls for distinguishing the frozen soils into a separate class. In permafrost zone along with frozen soils that include ice, there are waterless soils and rocks with negative temperature. The list of soils in the permafrost zone, would be incomplete without:1) ice-soil (more than 90 % of ice), 2) chilled soil of the temperature below 0 °C, 3) soil with positive temperature. Cooled plastic or loose soils with negative temperatures lie in cryolithozone where there are soluble minerals or saline groundwater. Soils with positive temperature lie everywhere under permafrost at different depths, in summer they also arise over permafrost. In some places they occur in cryolithozone.In the classification of soils we will adhere to the principles set out in the first article of the series. In respect of the classes, we divide soils by the type of the bonds in them. Firstly, we single out frozen soils with the bonds created by ice, and, secondly, conditionally waterless soils with negative temperature, where there is no ice and bonds are physical and physico-chemical. For brevity, the second class of frozen masses is convenient to call the special soil of permafrost zone. At the level of subclasses we specify the classification by the same types of bonds in soils. In each of these two classes we detach subclasses: 1) rock mass, 2) disperse mass and 3) «skadi». Among the frozen soils there are specific fourth subclass — ice soils. The classification in respect of the types is made for masses consisting entirely of soils with negative temperatures, as well as for masses including thawed soils. The author offers justification and discussion of the proposed classifications.

Subject: in this paper we discuss a method of calculation of the increase in mean water discharge during spring debacle of water streams in cryosphere. The main features of the debacle of water streams of river mouth zones in cryosphere are considered: ice drift, regular formation and destruction of ice jams, catastrophic floodings and washout holes. We discuss the methods of forecast of ice jams based on the estimate of the water discharge upstream of the potential cross-section of ice accumulation. Research objectives: theoretical investigation of flow velocity distribution over the depth of the stream during the ice breakup and its application for estimation of the stream velocity during the ice breakup. Materials and methods: the results of papers that describe the remote methods of estimating the speed of ice on the surface of water are analyzed. The aerophotography and satellite imagery methods, which enable us to estimate the stream velocity and water discharge during the ice breakup, are analyzed. These methods permit us to calculate current velocity profile and water discharge during breakup. Possibility of using logarithmic and power laws for description of flow velocity profile over the depth is investigated. The advantages of estimation of stream resistance with the help of Darcy-Weisbach coefficient in comparison with Manning’s roughness coefficient are discussed. Results: we consider application of power law for distribution of velocity over the depth to calculate the specific discharge of the water stream with ice floes on the surface. By integrating the specific discharge values through the width of a stream with the use of independently measured depth and water levels, one obtains water discharge of the stream. The method assumes that the ice run is not highly dense, and the stream velocity profile is not considerably different from that of an open stream due to the quick motion of ice on the water surface. Calculated magnitude of specific water discharge includes the water discharge moving along with the ice and the water discharge inside the permeable ice layer. The magnitudes of porosity of permeable ice layer during the ice breakup in rivers are presented. Conclusions: the research shows that application of power law velocity profile for estimation of stream discharge during the ice breakup has some advantages as compared with the logarithmic one. In particular, it becomes unnecessary to define the roughness coefficient during the ice drift, which is not a less difficult task than the estimation of water discharge. The improved method based on the power law velocity profile, developed in this paper, enables one to reduce the error of the method, as compared with the method based on logarithmic law velocity profile.