The Research Of Design And Control For Experiment Device Of Constant Water Pressure For Unsaturated Soil

The experiment device of constant water pressure for unsaturated soil is a kind of device for soil mechanics test to study the characteristics of underground soil,which has wide application in the field of ocean investigation and geotechnical engineering.This paper is based on the national 863 project of "the technology development and application of 60 meters multi-purpose drilling system in seabed " as the research background.Aiming at the needs of indoor test research on seabed sediment sampling,a experiment device is developed to provide constant water pressure for permeability test of seabed sediment.The main contents of this paper are as follows:1.According to the technical requirements and the design scheme of the experiment device,the design and relevant calculation of the structure components of the device are given,and the standard parts of them are selected,then the whole structure model of the device is established by the Solidworks.ANSYS is used to optimize the parts for design and is used to analysis for finite element simulation.2.The control system of device is designed by using LabVIEW,PLC,servo motor and other hardware and software facilities.Aiming at the matter that servo drive will be crashed due to the oversized servo displacement when the hydraulic cylinder piston arrives the end,a control method,the improved TLC control method,is put forward,and is designed through the program by using the LabVIEW and PLC.The simulation research of water pressure constant control is made by using MATLAB.According to the results of simulation research,a kind of constant pressure control method,the improved PID control method,is put forward,and is realized through the program by using PLC.3.Through building the platform of the experiment device,the proposed method to automatically eliminate the displacement of the servo and the proposed method of the constant pressure control are verified.The experimental results show that the corresponding control methods are effective and feasible.The control pressure error of the device for the full pressure control range and full flow output range is detected.The test results show that the maximum water pressure control error of the device is reduced by 0.5KPa compared with that of foreign countries.Therefore,the water pressure control precision is improved compared with that of foreign countries.Through the systematic research on the structure and control part of the experiment device,it provides theoretical and technical support for further research and development of the experiment device of constant water pressure for high control precision,it also establishes the foundation for the development of indoor test instrument for seabed sediment.