四平市的地下水超采及对策

四平是吉林省西南部的重要中等城市.总人口40.2万人,工农业总产值23.36亿元.主要靠开采地下水和利用市郊两座中型水库供水.日供水量9.48万m~3,缺水5.30万 m~3.由于长期供水不足,不但制约了经济的发展,也造成了地下水严重超采,引起环境水文地质条件不断恶化.这一问题已引起市政府及有关部门的重视.如何合理开发利用和保护管理地下水资源,防治危害,已成为亟待解决的课题.1 地下水超采现状四平市集中开采地下水已有50多年的历史.根据多年开发利用和勘察评价资料,市区有集中开采价值的赋水区为104km~2,可开采量不超过6.0万m~3/d(开采条件下的补给量为6.05万m~3/d).1960年有开采井28眼,开采面积18km~2,日开采量1.150万m~3.70年代后期,随着城市的发展,开采规模急     

Experimental Investigation on Vortex-Induced Vibration of Steel Catenary Riser

Steel catenary riser (SCR) is the transmission device between the seabed and the floating production facilities. As developments move into deeper water, the fatigue life of the riser can become critical to the whole production system, especially due to the vortex-induced vibration (VIV), which is the key factor to operational longevity. As a result, experimental investigation about VIV of the riser was performed in a large plane pool which is 60 m long, 36 m wide and 6.5 m deep. Experiments were developed to study the influence of current speed and seabed on VIV of SCR. The results show that amplitudes of strain and response frequencies increase with the current speed both in cross-flow (CF) and in-line (IL). When the current speed is high, multi-mode response is observed in the VIV motion. The amplitudes of strain in IL direction are not much smaller than those in CF direction. The seabed has influence on the response frequencies of riser and the positions of damage for riser.