Моделирование деформаций русел, сложенных мёрзлыми породами, при повышении температуры окружающей среды

This paper is devoted to investigation of the influence of river flow and of the temperature rise on the deformation of the coastal slopes composed of permafrost with the inclusion of ice layer. The method of investigation is the laboratory and mathematical modeling. The laboratory experiments have shown that an increase in water and air temperature changes in a laboratory analogue of permafrost causes deformation of the channel even without wave action, i.e. at steady-state flow and non-erosive water flow velocity. The previously developed model of the bed deformation was improved to account for long-term changes of soil structure with increasing temperature. The three-dimensional mathematical model of coastal slopes thermoerosion of the rivers flowing in permafrost regions, and its verification was based on the results of laboratory experiments conducted in the hydraulic tray. Analysis of the results of mathematical and laboratory modeling showed that bed deformation of the rivers flowing in the permafrost zone, significantly different from the deformation of channels composed of soils not susceptible to the influence of the phase transition «water-ice», and can occur even under the non-erosive velocity of the water flow.Работа посвящена исследованию влияния речного потока и повышения температуры воды на деформации береговых склонов, сложенных многолетнемёрзлыми породами с включением пластов льда. Методы исследования – лабораторное и математическое моделирование. Лабораторные эксперименты показали, что при повышении температуры воды и воздуха изменения в структуре лабораторного аналога многолетнемёрзлого грунта вызывают деформации русла даже без волнового воздействия, т.е. при стационарном режиме течения и неразмывающих скоростях водного потока. В связи с этим возникла необходимость усовершенствования разработанной ранее модели деформации русла с целью учёта долгопериодных изменений структуры грунта при повышении температуры воды. В основу трёхмерной математической модели термоэрозии береговых склонов рек, протекающих в районах развития многолетней мерзлоты, и её верификации положены результаты лабораторных экспериментов в гидравлическом лотке. Анализ результатов математического и лабораторного моделирования показал, что русловые деформации рек, протекающих в криолитозоне, значительно отличаются от деформаций русел, сложенных грунтами, не подверженными влиянию фазового перехода «вода–лёд», и могут наблюдаться даже при неразмывающих скоростях водного потока

LABORATORY RESEARCH OF DEFORMATIONS IN THE LOWER BYEF ON THE EXAMPLE OF THE RYBINSK WATER-ENGINEERING SYSTEM

Currently, the Russian rivers created by hydro, ensuring the solution of a large number of tasks that combine issues of livelihood and work of major industrial regions of the country. These facilities have significantly changed the natural regime of rivers and surrounding coastal areas. One of the main problems encountered during the construction and operation of hydro - negative channel processes downstream such as washouts and riverbeds destruction shores. Today this task is urgent, and even acute in some areas. However, some issues of erosion of banks and the reorganization of riverbeds downstream waterworks and their impact on the environment is not well understood. When activated, the lateral erosion develops general erosion processes with heterogeneous composition of sediments. In urban areas there is a risk of contamination of river water and coastal areas, damage to pipelines, dams collapse, flooding and inundation of large areas. The study and assessment of the extent of the dynamics of channel processes, allows us to develop recommendations, methods of forecasting and regulatory relief in order to prevent the negative consequences. It is necessary to solve problems that are important for the protection of rivers and coastal areas, and for the proper functioning of the industry and maintain the security of life of the population in such areas. The research of deformation shores downstream waterworks (for example, Rybinsk), a laboratory model at different levels of releases. The simulation showed that the strain is directly dependent on expenditures. However, if there is a permanent presence of transit charges, and it will be gradually added to the cost of other sources, the strain will be considerably less than the sudden release of water without transit

Strength of frozen soils during thawing

More than a third of the Earth's surface is subject to seasonal or prolonged soil frosts, and the recent warming of the climate requires revision of the construction standards in the conditions of permafrost because under heavy load in low-strength soils, there is a high risk of mobility of thawing rock and collapse of the construction structures, which is fraught with disastrous consequences. For design tasks it is necessary to know the behavior of frozen soils under certain changing conditions. This creates new requirements related to the degradation of permafrost and, as a result, the criteria for strength and stability of soils suitable for construction are changing. Calculation of loads during construction in the permafrost zone requires a special approach in each specific case, since it is impossible to make a single model in connection with the variety of soils and the history of their freezing. Soil typization does not give a clear picture at negative temperatures, since the transition "water-ice-water"in the soil changes the behavior of the grounds, and the unpredictability of climatic changes affecting this process greatly complicates the task. In the hydraulic laboratory of the RUDN University, a series of experiments was conducted for various types of soil subject to load, in order to determine the main parameters affecting the stability of soils during thawing, and to give approximate recommendations regarding the use of these soils as bases. © Published under licence by IOP Publishing Ltd

INFLUENCE OF RAINFALL PRECIPITATION ON THE DEFORMATION OF THE RIVER BANK CHANNELS IN PERMAFROST

We studied in the lab the interaction of river runoff from frozen soil, simulating the upper, active-layer, changing the thermal (warming) and mechanical (impact of rain) external influences. We determined the time of thawing of ground and infiltration in soil, sediment transport along the lines under the influence of slope flows, caused by both natural thawing permafrost and storm flows. A mathematical model for predicting the dynamics of river channels in the permafrost under the influence of external factors is suggested

Pilot study of influence of solar radiation on intensity of snowmelt

In the hydraulic laboratory of People's Friendship University of Russia a series of experiments to study the various possible external influences on the process of snow melting were carried out at the facility, which allows to measure the amount of seepage flow in time. The laboratory investigations of the continuous snow melting and infiltration of melt water into the ground, depending on the properties of the snow (initial density, thickness and temperature) were carried out. The impact of rain flows and radiation of the sun on the snow-melting process were examined, carried out experiments with exposure to infrared (IR) and ultraviolet (UV) radiation on the snow. The work is a continuation of the study of the dynamics of the coastal slope of the water bodies in a permafrost [1]

LABORATORY STUDY INFLUENCE OF FLOW ON THAWING OF UNDERWATER SLOPES AND THE PACE COASTAL EROSION OF RIVERS, OCCURING IN THE PERMAFROST ZONE

In the RUDN hydraulic laboratory researches of destruction of an underwater and surface coastal slope in the conditions imitating a kriolitozona depending on type of the soil composing a slope and a bias corner are executed. It is shown that the speed of an erosion of an underwater slope lags behind the speed of thawing of frozen soil. Work of a water stream considerably exceeds influence of other factors (temperature, wind influence, solar radiation), leading to formation of niches of washing away. Work is continuation of a research of dynamics of a coastal slope of water objects in the conditions of a kriolitozona [1-4]

Modeling of river bed deformation composed of frozen sediments with increasing environmental temperature

This paper is devoted to investigation of the influence of river flow and of the temperature rise on the deformation of the coastal slopes composed of permafrost with the inclusion of ice layer. The method of investigation is the laboratory and mathematical modeling. The laboratory experiments have shown that an increase in water and air temperature changes in a laboratory analogue of permafrost causes deformation of the channel even without wave action, i.e. at steady-state flow and non-erosive water flow velocity. The previously developed model of the bed deformation was improved to account for long-term changes of soil structure with increasing temperature. The three-dimensional mathematical model of coastal slopes thermoerosion of the rivers flowing in permafrost regions, and its verification was based on the results of laboratory experiments conducted in the hydraulic tray. Analysis of the results of mathematical and laboratory modeling showed that bed deformation of the rivers flowing in the permafrost zone, significantly different from the deformation of channels composed of soils not susceptible to the influence of the phase transition «water-ice», and can occur even under the non-erosive velocity of the water flow

Laboratory research of snow melting as component of seasonal process of deformations stream channel

A laboratory study of the process of continuous snowmelt and subsequent infiltration of meltwater into the soil, depending on the properties (different initial density, layer thickness and temperature) of snow. We consider the impact of storm flows in the process of thawing

ВЛИЯНИЕ ОСАДКОВ В ВИДЕ ДОЖДЯ НА ДЕФОРМАЦИИ БЕРЕГОВОГО СКЛОНА РУСЕЛ РЕК В УСЛОВИЯХ МНОГОЛЕТНЕМЁРЗЛЫХ ПОРОД

We studied in the lab the interaction of river runoff from frozen soil, simulating the upper, active-layer, changing the thermal (warming) and mechanical (impact of rain) external influences. We determined the time of thawing of ground and infiltration in soil, sediment transport along the lines under the influence of slope flows, caused by both natural thawing permafrost and storm flows. A mathematical model for predicting the dynamics of river channels in the permafrost under the influence of external factors is suggested.Впервые в лабораторных условиях исследовалось взаимодействие речного стока с мёрзлыми грунтами при изменении термических (потепление) и механических (влияние дождя) внешних воздействий. Определялись время оттаивания грунта, инфильтрация в грунте, перенос наносов в русле под воздействием склоновых потоков, вызванных как естественным оттаиванием мёрзлых грунтов, так и дождевыми потоками. Предложена математическая модель прогнозирования динамики русла рек в многолетнемёрзлых породах под влиянием внешних воздействий