Research Of Seafloor Cone Penetration Technology Powered By Seawater Pressure Energy

In the process of marine resource development,the offshore oil and gas development platform and offshore wind turbine generator foundation stability evaluation,international optical cable route survey,seabed mineral resource exploration need to master detailed and accurate seabed engineering geological conditions,such data for the development and utilization of marine resources Of great significance,more and more subsea in-situ testing techniques are applied to marine engineering geological surveys.Among the two main types of submarine static penetration technology,the seabed static penetration technology is superior to the downhole static penetration technology,with the advantages of convenient decentralized recovery,continuous probe path,high efficiency,etc.However,the probe driving system of the seabed static penetration technology is a motor or a hydraulic drive system,and the overall structure is complicated,the reliability is low.This paper designs a submarine static penetration driving system based on seawater hydrostatic pressure energy.This system does not need to carry underwater motor,hydraulic pump,umbilical cable,large-capacity battery and power distribution and power electronic equipment.The pressure difference between the seawater pressure and the self-contained low-pressure cavity is directly used to drive the probe into the ground.Compared with the conventional driving method,the structure is simple and the reliability is high.The driving system adopts a secondary adjustment system to control the movement speed of the probe,ensuring that the penetration rod maintains the drilling speed substantially constant under the formation resistance and has high energy conversion efficiency.In this paper,the structure of the drive system is proposed,and its mathematical model is established.Based on the mathematical model,the stability of the system,the speed control error,the natural frequency and damping of the system are analyzed.The analysis results show that increasing the mechanical system's moment of inertia,reducing the seawater pressure and increasing the control gain can improve the stability of the system.Based on the model,the speed errorformula is derived.According to the working conditions and error formula,the system parameters can be adjusted to stabilize the probe speed at 10 % error range.Based on the theoretical analysis results and the requirements of the system,the drive system test bench was designed and built.The lower computer software and the upper computer software system were developed.The different operating conditions of the drive system were tested.The effective test data was collected and analyzed.The system speed error data and conversion efficiency of system energy were obtained.The feasibility of the system was verified,and a good foundation was established for the improved test of the subsequent system...