Research On Comprehensive Measurement Of Static Sounding And Shallow Gas

With the development of economy and science and technology,the ocean with rich natural resources has become a hot spot for resource development in the new era.The development of resources in the ocean depends on the construction of marine engineering,and the most important thing before the construction of marine engineering is to determine the mechanical properties of the submarine soil.The determination of the basic mechanical properties of the submarine soil and the bearing capacity of the foundation are important test items for marine engineering surveys.Shallow gas is widely distributed in the near-gulf area and the main gascomponent is methane gas,and the submarine soil layer with shallow gas will destroy the structure of the marine engineering and affect the safety of the construction personnel.At present,the domestic testing of mechanical properties and shallow gas before the construction of marine engineering is conducted separately,which takes time and effort,do not even conduct shallow gas detection,leaving security risks.Moreover,the detection of shallow gas is mainly carried out by manually extracting the gas sample and then performing laboratory testing.There are problems such as low automation,high detection cost and inability to detect in real time.In view of the above problems,this paper has designed a Static sounding and shallow gas comprehensive detection device,which can simultaneously measure the mechanical properties of submarine sediments and the concentration of methane in shallow gas,and through the ultrasonic wireless transmission part,the output data of the seabed sediment mechanical property detection part is transmitted to the shallow gas detection part.Compared with the traditional shallow gas detection device,this design can stably detect shallow gas in a wide concentration range,the detection data has real-time performance and short response time.The main work and specific research contents of this paper are as follows:(1)Researched the main detection methods of static sounding and shallow gas at present,and analyzed the advantages and disadvantages of each method,and proposed the purpose of this research,the main work and the key technical problems that need to be solved.(2)The overall plan of the instrument is proposed,which mainly includes the overall mechanical structure design and key component design.The design of the mechanical structure includes the design of the mud water-gas separation structure,the design of the sealing head and the design of the adapter.The key component designs include the selection of mechanical property detection sensors,the selection of methane detection sensors,the selection of membranes and permeable stones,the selection of acoustic wave transducers and the selection of modulation and demodulation techniques.(3)Carry out the overall hardware design of the instrument,mainly including mechanical characteristic parameter measurement circuit design,shallow gas detection processor circuit design,gas sensor output signal reading circuit design,power supply circuit design,wired data transmission circuit design and modulation and demodulation Circuit design.(4)The overall software design of the instrument is carried out,which mainly includes the design of multi-channel ADC sampling software,coding program design and decoding program design.(5)Carried out system tests and analysis of on-site test results.First,the signal transmission and reception experiments were carried out,the output waveforms of each stage of signal transmission were measured to verify the feasibility of wireless signal transmission,methane detection experiments with different concentrations were carried out,and then field tests for shallow gas detection were conducted,and the test results were analyzed and summarized.The static sounding and shallow gas comprehensive measurement device proposed in this subject can achieve one-time intrusion into the seabed sediments,at the same time measure the mechanical characteristics of the seabed sediments and the methane concentration in the shallow gas,and obtain real-time detection data to guide the ocean Engineering construction to ensure the quality of marine engineering and protect the safety of construction personnel.