Research On Key Techniques Of Measurement Equipment For Acoustics-pressure Characteristics Of Seafloor Sediments

With the large consumption of land resources,the efforts of the development of ocean keep on heating.As the lower boundary of the sea,the sea bottom is the key area of the research of the ocean,extracting physical and mechanical properties of seabed sediments by acoustic method which is an important method for the research of the seabed.Because most of the acoustic measurements are sampled and measured in laboratory in our country,which ignore the stress state of the ocean floor,it is a key technology to develop measurement equipment for acoustics-pressure characteristics of seafloor sediments,conducting test for acoustics-pressure characteristics of seafloor sediments based on the equipment is a bound link between laboratory measurement technology and in-situ measurement technique,through researching the effect of the acoustic properties of sediments by hydrostatic pressure systematically,solving the problem of sampling measurement out of in-situ state and researching the acoustic velocity difference of the same type of seafloor sediments in different seabed systematically.Measurement equipment for acoustics-pressure characteristics of seafloor sediments,which designed based on programmable logic controller PLC measurement and control platform?the servo pressure control?stepper drive control?multi-sensor measurement ? touch screen interaction and other functions to implement pressure controlled acoustic measurement.The equipment can achieve the automatic pres sure control of pore water of seafloor sediments samples,pressure up to 30 MPa pressure control accuracy up to 0.1MPa,ensure the uniform pressure of the sediment samples by the pressure holding time can be adjusted,control the propulsion accuracy of the piston rod in the test chamber to adapt to different length samples in 0.1mm.Main contents of this paper are as follows:Based on the analysis of the characteristics and disadvantages of simulation equipment for seabed pressure environment,proposed overall scheme and key techniques of measurement equipment for acoustics-pressure characteristics of seafloor sediments;The influence of the deformation of the test chamber on the accuracy of the acoustic measurement is analyzed;Conducted hardware design of control system of equipment,which includes equipment's overall circuit,servo pressure control?stepper drive control?multi-sensor measurement module,touch screen?controller PLC,etc;According to the design requirements of the equipment for T-shaped program design including automatic and manual pressure,holding pressure,test chamber space adjustment,ect and touch screen control design;The equipment was debugged,tested for performance and the seabed sediment acoustic experiment is carried out based on the equipment.Performance test of equipment,including automatic pressure,holding time and manual pressurization,chamber distance adjustment,indicating that equipment can achieve the desired function and accuracy.Equipment was used to verify velocity-pressure characteristics of water,and based on experimental results of velocity-pressure characteristics of the seabed sediments of equipment are in agreement with the theoretical results of the literature,which indicated that equipment meeted the intended design requirements.