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在离开 Yucatar 半岛的 Campeche 海堤处的浅海中做了一项实验,此项实验是为了测量简正波幅度函数和衰减系数而设计的。测量是在海堤的两个测位上进行的,该处水深约30米;下面是坚实的石灰石底,其中已测得声速为每秒1900米。所用脉冲连续波信号的频率是400赫,750赫和1500赫。利用海底液态模型而计算得到的简正波幅度函数理论值同测量值符合得很好。为了使所测得的简正波衰减系数同理论值相一致,需要假设该海底的切变速度是每秒钟1000米.此值低于水层中的最小声速,所以海底中传播切变波的产生是引起衰减的主要机制.在两个测位上测得的简正波衰减系数有着显著的差别,这可以用水层底部低速声道的深化来解释.
An experiment was conducted in the shallow sea off the Campeche sea dike in the Yucatar peninsula, designed to measure the amplitude and attenuation coefficients of a simple normal wave. The measurements were made on two seawalls with water depths of about 30 meters; underneath was a solid limestone floor with a measured sound velocity of 1900 meters per second. The frequency of the pulsed CW signal used is 400 Hz, 750 Hz and 1500 Hz. The theoretical value of the amplitude of the normalized wave function calculated by the liquid-sea model of the sea is in good agreement with the measured value. In order to make the measured simple normal attenuation coefficient consistent with the theoretical value, it is necessary to assume that the shear rate of the seafloor is 1000 meters per second, which is lower than the minimum velocity of sound in the water layer, so the propagation of shear waves in the sea floor is generated Is the main mechanism that causes attenuation.The difference between the attenuation coefficients of normalized waves measured at the two locations is significantly different, which can be explained by the deepening of the low velocity channel at the bottom of the aquifer.