Study on the Distribution Characteristics of Shallow Gas in the Submarine Pipeline Route Area of Hangzhou Bay

As a geological disaster, the development of shallow gas in shallow strata will have a long-term and hidden adverse impact on the stability of submarine pipelines. In order to ensure the safe operation of submarine pipelines, it is necessary to find out the distribution characteristics and development degree of shallow gas. The shallow gas situation in the submarine pipeline routing area in the north and south island areas of Hangzhou Bay was studied by using the method of middle-shallow stratum profile detection. The shallow gas in the north side of the submarine pipeline is mainly distributed near the landing sections of the north and south banks, and the gas cap is buried in a shallow depth, which is dispersed and disseminated. The shallow gas of the submarine pipeline in the south island area is widely distributed and continuous, and the buried depth of the gas cap is shallow. Under different sedimentary environments and different current erosion actions, shallow gas may cause the sea pipe to be exposed and the bearing capacity of the stratum under the sea pipe to decrease, resulting in shear failure.