Seismic profiling of the sea-bottom in recognition of geotechnical condition

Abstract

Seismic surveys are widely applied in research on the recognition of geological and geotechnical conditions of seabed and ocean floor sediments. The methodology and equipment needed to carry out shallow seismic and direct geotechnical surveys, as well as the analysis of the results based on the survey of the Polish Baltic Sea bottom, shall be presented here. The interpretation of the seismic survey results is based on the analysis of the registration of different acoustic levels, characteristics of seismo-acoustic layers, their degree of readability and slope angles of individual acoustic reflections. The author deals with the analyses of seismic reflection data and tries to understand the wave image as best as possible. Based on the seismic registrations obtained by the Geofizyka-Torun company, the author has elaborated interpretation patterns for the Polish Baltic sediments, which are also presented here. The seismic surveys were used to construct maps of specific levels with different geotechnical conditions in the sea-bottom and at a depth of 10, 20 and 30 m below the seabed. The author presents here new results of research related to the geotechnical characteristics of the Polish Baltic substrate at a depth of 30 m below the seabed. The geotechnical map of the Polish Baltic Sea of the substrate at the depth of 30 m below the sea-bottom, as prepared by the author, is very important for building deep foundations of marine constructions, such as oil and gas exploration and production platforms. Seismic surveys allow a good degree of recognition of various geotechnical types of soils in the Polish Baltic sea-bottom, for which approximate values of characteristic geotechnical parameters have been determined.