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本文叙述了生产天然气的毛伊海上钻井平台的地震警报系统,该平台位于新西兰海岸的塔斯曼海近海处。当加速度达到该平台的设计标准的一半时,该警报系统的功能就是给予紧急报警,以便能够实行安全措施。该警报系统的设计只用于监测平台的低频振动类型响应,因这些低频振动类型会对平台中的应力起着主要作用。进行的环境振动测量表明,6个最低频的振动类型的频率值是0.45赫至1.35赫不等。该警报系统就是按此要求设计的,因此,来自转换器的信号通过一个具有极小平坦频率响应的滤波器,该滤波器的带宽为0.3赫至2赫,响应曲线在较高频处,每倍频程24分贝急剧偏离。为减少误报的危险性,在海岸上安装了拥有类似检波器的无线电接收线路,对是否发生地震给予确认。
This paper describes an earthquake alert system for a Maui offshore drilling rig producing natural gas located off the Tasman Sea off the New Zealand coast. When acceleration reaches half the design standard of the platform, the alarm system’s function is to give an emergency alarm in order to be able to implement safety measures. The alarm system was designed to monitor only the low frequency vibration type response of the platform, as these types of low frequency vibrations play a major role in the stress in the platform. Environmental vibration measurements conducted showed that the frequency of the six lowest frequency vibration types ranged from 0.45 Hz to 1.35 Hz. The alarm system was designed so that the signal from the converter passes through a filter with a very small flat frequency response with a bandwidth of 0.3 Hz to 2 Hz and a higher response frequency at Octave range 24 dB sharp departure. To reduce the risk of false positives, a similar receiver-equipped radio receiver line was installed on the coast to confirm the occurrence of an earthquake.