The Application of Distributed Acoustic Sensing for Shallow Marine Investigations – an Intertidal Case Study

Typically, there is a paucity of geotechnical information available to designers of offshore foundations for marine renewable structures, which often results in highly conservative designs. Recent innovations offshore (e.g. McGrath et al. 2016; Long et al. 2020)) seismic surface wave (SW) measurements have highlighted their potential for providing offshore geotechnical information, thereby reducing design uncertainty. There is also an increasing recognition of the value of these measurements from the geotechnical industry, with Lunne (2013) recommending that measurements of seismic shear wave velocities (Vs) should be standard practice for important offshore site investigations. Vs is related to the small strain shear modulus Gmax, which is a critical input parameter for several applications, including static and dynamic analysis of foundation systems, soil liquefaction analysis and input for advanced constitutive soil models. The main disadvantage of current offshore SW practice is a relatively slow data acquisition procedure, which, in turn reduces the spatial coverage of the approach.