Study on a method of the shear wave velocity in surficial marine Hedoro sediment layer using radiation impedance method

1.理论分析研究了Hedoro沉积层等高孔隙率海洋沉积物圆形振动板的辐射阻抗频率特性。考虑了Hedoro沉积物的孔隙度、浓度和横波速度之间的关系。实验(1)用辐射阻抗法测量了明胶作为剪切波速很慢的介质时的横波速度，该介质与高孔隙率的Hedoro沉积物一样。明胶浓度从2.5%变化到50%。从测量结果可以看出，剪切波速随着浓度的增加而增大。(2)用辐射入射…测量了1)高岭土悬浮液、2)Kibuhi粘土、3)口池港海底沉积物、4)清水港海底沉积物的横波速度。更多的舞步方法。从测量结果可以看出，对于所有的泥沙模型，剪切波速都随着孔隙度的减小而增加。然而，横波速度的孔隙度特征与介质的类型有关。这一结果被认为是因为尽管孔隙度相同，但泥沙模型的颗粒尺寸、颗粒形状和骨架结构都不同。测量系统的研制(1)需要在现场快速测量横波速度。研究了一种通过将测力传感器和加速度计的脉冲响应输入到FFT分析仪来快速获得辐射阻抗的方法。可以看出，脉冲响应法的测量结果与正弦波响应法的测量结果基本一致。(2)在特殊定制的防水容器中设置了带有拾力器和加速度计的可控震源。传感器电缆和振动器驱动电缆都进行了防水处理。此外，还设计了避免测力装置的装置，并展望了该测量系统在原位测量Hedoro沉积物剪切波速方面的应用前景。较少

1. Theoretical analysisThe frequency characteristics of the radiation impedance of the circular vibrating plate for high porosity marine sediment such as Hedoro sediment layer were investigated. The relationship between the porosity, the concentration and the shear wave velocity of Hedoro sediment were considered.2. Experiments(1) the shear wave velocity of gelatin which is seemed to be the medium with very slow shear wave velocity just same as high porosity Hedoro sediment were measured using the radiation impedance method. The concentration of gelatin was changed from 2.5% to 50%. From the measured results, it is seen that the shear wave velocity increases, as the concentration increases. It is also seen that the very slow shear wave velocity (0.07m/s) can be measured using the radiation impedance method.(2) The shear wave velocity of 1) Kaolin suspension, 2) Kibushi clay, 3) Seabed sediment of off-Kouchi port, 4) Seabed sediment of Shimizu port were measure using the radiation imped … More ance method. From the measured results, it is seen that the shear wave velocity increases, as the porosity decreases, for all sediment models. However, the porosity characteristics of the shear wave velocity are dependent on the kind of the medium. This results is considered due to the reason that the grain size, the grain shape and the structure of the frame of the sediment models are different, even though the porosity is the same.3. Development of a measuring system(1) It is necessary to measure the shear wave velocity rapidly in situ. A method for obtaining the radiation impedance rapidly by inputting the pulse responses of the force pickup and the accelerometer to a FFT analyzer was investigated. It is seen that the measured results using the pulse response method is almost agreed with that using the sinewave response method.(2) The vibrator with the force pickup and the accelerometer was set in the specially ordered waterproof vessel. The sensor cables and the vibrator driving cables were waterproofed. Moreover, the device to avoid the extra force to the force pickup was done.The prospects for the in situ measurements of the shear wave velocity of Hedoro sediments using the measuring system are obtained. Less