Research On Shallow Sea Sediments Penetrometer Measurement System

The shallow sea sediment probe measurement system is a system for rapidly measuring the intensity of shallow sea sediment by using shallow sea sediment probe.Shallow sea sediment probe can measure the intensity of sediment layer in the shallow sea area within 20-200 meters depth.The system has the advantages of simple operation,rapid measurement,etc.,and provides important information for the development and utilization of marine resources,the description of the marine geography and geomorphology and the national defense safety.There are many different types of sediment probe,which can be divided into different categories: the Doppler probe,the mechanics probe,the acceleration probe and so on.According to the measurement range it can be divided into two types:shallow sea and deep sea.According to the signal transmission mode it can be divided into wire probe and wireless probe.Since the development and utilization of marine resources by human at present is mainly limited in the shallow sea area,and additionally the marine environment has intense attenuation and refraction to acoustic signals,wired probe for shallow sea is the current development trend,and is also the main research area of sedimentary layer probe.In this paper,based on the measurement principle,the mathematical and physical model of the acceleration probe,an acceleration free fall shallow sea sediment probe and a matched measurement system is designed and implemented.The system can be used to measure the intensity of the sedimentary layer in 20-200 meters deep underwater in shallow sea area,and the sediments can be classified by calculating the elastic modulus.The system is composed of an acquisition unit and a deck unit.The acquisition unit comprises a probe body and a signal line,while the deck unit comprises a data acquisition control box and a computer.Acquisition circuit is loaded in the probe,and sends out collected acceleration data through the RS-485 after being thrown into sea water.The deck unit is fixed on the deck.The data acquisition control box receives data from the acquisition unit,and then communicates with the computer through the USB protocol.The computer runs user interface and data storage program coded in Lab VIEW to display the real-time measuring curve.In order to realize the classification of the sediment intensity,the data are analyzed in time domain and frequency domain respectively.In the time domainanalysis,the intensity of the sedimentary layer is classified by theoretical calculation of elastic modulus.While in the frequency domain analysis,amplitude spectrum of the discrete Fourier transformation is used to distinguish the different deposition intensity.In order to test the performance of shallow sea sediment probe measurement system,the following experiments were carried out:(1)In the laboratory environment,the different soil samples with different saturation and different types were tested and the classification was realized.(2)In the lake environment,the lake sediment was tested to verify the availability of the mechanical structure and data transmission function.(3)The system had been tested in the shallow sea area of known sedimentary type,and the design goals were achieved.