ИСТИНА

There are serious problems with the reliability of buildings and structures in towns and villages of the Chukchi Autonomous District,. Deformation of objects connected not only with the abandonment of the last 15-20 years many of the mines and towns, the lack of engineering geocryological monitoring, lack of maintenance and construction services, but also with the development of dangerous cryogenic processes: reduction of the bearing capacity of foundations for heating frozen grounds, the activation slope processes, freezing and destruction of the foundations, etc. The largest settlement with a predominance of the indigenous population are located on sea coasts composed icy frozen soils, which are subjected to thermal abrasion. Retreating of shores of the Arctic – is an established fact. According to various sources, Russia for one year due to coastal retreat loses about 30 km2 [6]. Under thermal abrasion is understanding the wave impact on the shore, composed of icy deposits. Thermoerosion factors can serve as lithology, temperature and ice content of frozen shores, and climatic factors (duration of ice-free time, the frequency of storms, the main wind direction, etc.). To assess the engineering and permafrost hazards associated with thermal abrasion of Arctic coast, was selected the national settlement Lorino (pop. 1,400), located 500 km on the E-N-E of Anadyr on the shore of the Chukchi Sea [2,7]. Changing the position of the coastal scarp estimated by geodetic materials (reports on conducting geodetic surveys, reflect the situation in certain periods of time in the 1967-92 years.), and space images of different years with regard to litho-genetic conditions of the territory. As a result, over 25 years the area around the Lorino and himself fell by 2.5% (10,000 m2) due to thermal abrasion coasts, and became unsuitable for the operation of 9% (35,000 m2) of the village because of the linear thermoerosion. Coastal scarp retreated by an average of 12 meters, sometimes up to 45 m. But comparing satellite image (with resolution 0.5 m) of 2010 year and map of shore retreat for 1967-1992, speed of shore retreat is significantly decreased. It may be caused by exposure of more resistant rocks to thermal abrasion. By Zhestkova [8] and Shur et al. [9], among the unconsolidated frozen rocks the most susceptible to erosion by are sands with a high content of ice, and the least are clay with a low content of the ice. There is supposed, that at the base of the erosion bank clay was exposed. At the summer of 2012 field expedition had comprehensive investigation of this feature and confirmed this. There were explored clays in the base of shore slope - the deposit more resistant to thermal abrasion than loam and sands. For Lorino developed a preliminary forecast of enhancing thermal abrasion and the basic techniques to stabilize the situation, but the problems of other coastal settlements of Chukotka experiencing similar adverse impacts are not addressed. Relevant is also the development of methods to ensure the reliability of frozen foundation built and operated facilities in Chukotka.