Save Alexander Column in St. Petersburg
The Eighth Wonder of the World - Alexander Column was erected in St. Petersburg under the direction of Auguste de Montferrand in 1834, is made of granite rapakivi (in Finnish - “rotten stone”). The peculiarity of granite as one of the varieties of intrusive rocks, is the high level of residual (“frozen”) microstrain. Process of successive crystallization minerals granite intrusion from 1400 ° C ends the crystallization of quartz at ~ 600 ° C (Bowen number). Differentiation of elastic and thermal properties of minerals composing the granite leads to the formation of microstrain, reaching ~ 50 MPa under normal conditions. When separating of an array granite monolith, residual stresses mikro destruction stimulate the development and in conjunction with the penetration of moisture and its subsequent freezing at low temperatures lead to the formation of the surface macro-cracks. Periodic seasonal and daily temperature fluctuations, up to ± 30 ° C in St. Petersburg, cause the development of bulk stress in the body of the column, which can not be excluded sealing macro-cracks on the surface. A good example is the spontaneous destruction of granite vases in 2008 in the Summer Garden (a gift from Charles XIV Nicholas I, set in 1839). Accelerating the process of destruction of the Alexander Column (currently in the column there were 27 fractures, a total length of more than 8 meters) requires the immediate adoption of effective measures for the conservation of this magnificent historical monument of Russia. In this paper we propose measures to stabilize the degradation of the Alexander Column, including proposals for the draft protection from aggressive environmental influences and anthropogenic impacts.