Design And Study Of In-situ Sampling Column For Pore Water In Submarine Sediment

In situ sampling column for pore water of submarine sediment is a device for collecting pore water,which is widely used in exploitation of marine resources,survey of submarine geological,change of earth climate and other research areas.This article relies on the national 863 plan " Development of in-situ sampling column for pore water of sediment ".Based on in-situ sampling system of pore water during the 11 th Five-Year Plan,in-situ sampling column is improved according to shortcomings of system device and engineering demand in order to improve sampling and filtration performance of the device.Device after improved design can simultaneously separate surface seawater and sediment pore water to ensure the collect sample's air tightness and fidelity,which provide high-tech support for China's marine sciences field in natural gas hydrate search for mineral resources and resource assessmen aspects.The specific research work of full text is summarized as follows:(1)This paper overviews the research status of in situ sampling system of pore water in submarine sediment,anslyzing and summaring the current research problems,and then determining overall design scheme and working principle which can meet relevant technical requirements of in situ sampling column.Dimension parameter design and structural design of the device components are carried out on the basis of overall design scheme,and material selection and performance characteristics of each part of structure are analyzed.(2)Through static analysis module of ANSYS Workbench,the bending strength of double bottle in situ sampling column is analyzed based on actual working conditions,and analysis objects include solenoid valve mounting cylinder,sampling cylinder and double clamps.The analysis results show that overall in situ sampling column has reasonable structural design,reliable performance,and meets requirements of strength and stiffness of material.In addition,FLUENT flow analysis software was used to analyze the external flow field of a single bottle in situ sampling column under laboratory environment and three different filter apertures.The results show that pore water of the sampling column with pore size of 1mm has the lowest damage impact to outer filter screen,and the filtration effect is the best.(3)ANSYS Workbench finite element simulation software was used to optimize response surface of a single bottle in situ sampling column about shell tube and base,which is used under simulated test condition.In this paper,important parameters of shell tube and base are taken as input parameters.At the same time,mass,maximum deformation and maximum equivalent stress are looked as output parameters.In additon,mass minimization and maximum equivalent stress under specified range are considered as constraint condition.Before optimizing design analysis,we need to use Solidworks 3D software to parameterize model.Model structure after optimized design can not only meet requirements of material performance,but also decrease in quality,so as to save material and reduce manufacturing cost.(4)Based on the experimental platform of Marine Laboratory,a confirmatory filtration test was carried out on a single bottle in situ sampling column.Test objects included three kinds of single bottle in situ sampling columns with filter pore diameters of 1mm,1.5mm and 2mm respectively.By comparing the turbidity degree of pore water samples collected by the three devices,it is judged that the optimum sampling and filtering device.Before the experiment,the real seabed sediments of different seas are tested,and the particle size range of seabed sediments is obtained,which can provide reference for design of external filter layer.After repeated tests,the test results are consistent with theoretical simulation results,and ultimately determine the filtering aperture of 1mm in situ sampling column can be used as the best sampling filter equipment,so as to improve the overall filtration performance of the device.