Comperhensive Detection Techonlogy Of Shallow Gas In Deep Soft In Oujiang Estuary Area Experimental Research

A large amount of underground shallow gas(methane)is distributed in the deep and soft soil layer in the Oujiangkou area of Wenzhou.Due to its hidden and heterogeneous occurrence form,with the development of urban underground space construction,traditional engineering drilling and exploration methods cannot be completed.Eliminate the shallow underground gas.Once the shallow gas erupts,it will disturb the structure of the soft soil layer,cause ground subsidence,and even cause methane explosion accidents.It brings a series of safety hazards to the construction of urban infrastructure projects,which must be solved in the construction of underground projects.Geological issues.As an advanced engineering detection method,the geophysical method has the advantages of simple operation,high detection efficiency,and rich exploration information.According to the shallow gas geological exploration data,the static pressure controlled release gas technology is the experimental basis,combined with multi-function In-situ cone penetration,electrical method,seismic wave and other technical characteristics,systematically carry out the comprehensive detection technology test research of shallow gas in Lingkun Island area,and compare and analyze the changes of related geophysical signals during the static pressure release of shallow gas.The research work has achieved the following main Achievements and understanding:(1)The survey and research of shallow gas in deep and soft soil layers in the Oujiang Estuary area has been systematically carried out.Including the occurrence of shallow gas in the northern mouth of the Oujiang River,investigation and analysis of comprehensive detection methods,site selection,and detection test plans.These comprehensive preparations have provided very strong support for the comprehensive detection of shallow gas.(2)Using multifunctional resistivity in-situ static cone penetration technology to carry out in-situ testing of shallow gas formations,achieving the purpose of accurate stratigraphic division of soft soil layers and judging the location of shallow gas deposits.(3)Conduct comprehensive tests combining multiple detection technologies in deep and thick soft soil areas to detect the occurrence information of shallow underground gas.Using the inversion calculation results of the surveying geoelectric method,seismic scattering,seismic CT and other data,combined with the geological data of the test area,the shallow gas interpretation work is comprehensively analyzed,and the distribution information of the deep soft soil layer in the test area and the shallow gas distribution are given.Store the location signal characteristics and the area affected by the shallow gas release.Emphasize the combination of multiple geophysical exploration methods and comprehensive analysis of the occurrence of shallow gas in order to reduce the uncertainty of the geophysical interpretation results.