Failure characteristics of surface vertical wells for relieved coal gas and their influencing factors in Huainan mining area

Based on data from through-hole and logging,we studied the failure characteristics of surface drainage wells for relieved coal gas in Huainan mining area and its influencing factors.The results show that the damaged positions of drainage wells are mainly located at the thick clay layer in the low alluvium and the lithological interface in the upper section of bedrock in west mining area.The failure depth of casing is 244-670 m and concentrates at about 270-460 m deep.These damaged positions are mainly located in the bending zone according to three zones of rock layers in the vertical section above the roof divided. Generally,the casing begins to deform or damage before the face line about 30-150 m.Special formation structure and rock mass properties are the direct causes of the casing failure,high mining height and fast advancing speed are fundamental reasons for rock mass damage.However,the borehole configuration and spacing to the casing failure are not very clear.

INFLUENCE OF CURRENIS ON WAVES AT STRONG TIDE AND ESTUARY AREA

As known to all, tides and river discharge at both the Yangtze River Estuary and Hangzhou Bay are quite strong. So the wave data measured at these regions must have been affected by current. Since the combination of current with wave climate is a random process, i. e. spring tide may be met with small waves, or neap tide with strong waves, so the measured wave data related to the wind data have great divergence under the influence of current. In this paper, based on the research of wave refraction by influence of both current and water depth (Pan and Li, 1987), the influence of tide current and river discharge on the wave parameters in Luojing area of Yangtze River Etuary and Beilum harbour area are discussed. As a conclusion, for determining the design wave in still water, or for establishing the relationship between waves and winds, pure wave data should be separated from the measured wave data.

Geopolitical Analysis of the Entry of Finland and Sweden to the North Atlantic Treaty Organization(NATO)

Russia’s invasion of Ukraine has significantly altered the pattern of alliances and geopolitical balances on the European continent to such an extent that countries like Finland and Sweden that have traditionally remained neutral are now applying to join the North Atlantic Treaty Organization(NATO).These two countries fear that Russia,which is currently trying to reposition itself,could try in the near future to invade these two Nordic countries to prevent the West(European Union,United Kingdom,and United States)from increasing its military presence and its military force in the Scandinavian peninsula and in the Baltic Sea.The enlargement that the European Union(EU)has carried out since the 1990s,and that has also meant the expansion of NATO,has been viewed with great concern by the government of Vladimir Putin,who considers that the United States and the European Union did not fulfill their commitment to former Russian President Mikhail Gorbachev to respect the sphere of influence of the former Union of Soviet Socialist Republics(USSR).Within the framework of this geopolitical confrontation,Helsinki and Stockholm do not want to run the risk of being invaded by the Russian army,which is why they seek to take advantage of the principle of collective security that NATO membership would grant them.