Mukhopadhyay, Raja
Marine geophysical surveys for geotechnical appraisal off manjeshwaram, Kasaragod, Kerala - Vol.52(1), Feb - USA Springer 2022 - 125-131p.
Single-channel marine seismic reflection and bathymetric surveys were conducted along 160l km off Manjeshwaram, Kerala coast, as a part of a geotechnical appraisal. The quality of overburden and depth to bedrock are prerequisites for any geotechnical planning since subsurface dredging for channels or the base of a foundation for any subsequent structures and their cost implications can be estimated. They help to arrive at a techno-economically viable decision for building harbour, jetty or any other related structures. The seismic survey can assess all these parameters with the validation of a few boreholes from the respective areas. Though boreholes provide precise geological information at discrete locations, the procedure of drilling of boreholes in the sea is both times consuming and expensive. Further, the interpolation of geological information between two holes in a nearshore environment is not advisable as rapid variations in strata can occur within the shallow geological sequences. It is, therefore, desirable to undertake site-specific marine geophysical surveys and a limited number of borehole drilling to corroborate the findings. Though during the time of the survey, there was no such drilling information and there is a plan of developing port or harbour in the future, the seismic results can be corroborated with the borehole that would have been proposed at that time. Since the compressional (P-wave) and shear (S-wave) velocities along with density of different geological layers are the controlling factors for the assessment of geotechnical parameters and single-channel seismic reflection survey displays the vertical subsurface images in Two Way Time, it is little handicapped without borehole information for the depth and quality of different strata. The efficacy of the survey lies in the fact that it can reduce the number of boreholes and thus minimizes the cost and makes fewer hazards to the environment. It also reduces the lateral surprises that are sometimes encountered by nearby boreholes.
Civil Engineering
Marine geophysical surveys for geotechnical appraisal off manjeshwaram, Kasaragod, Kerala - Vol.52(1), Feb - USA Springer 2022 - 125-131p.
Single-channel marine seismic reflection and bathymetric surveys were conducted along 160l km off Manjeshwaram, Kerala coast, as a part of a geotechnical appraisal. The quality of overburden and depth to bedrock are prerequisites for any geotechnical planning since subsurface dredging for channels or the base of a foundation for any subsequent structures and their cost implications can be estimated. They help to arrive at a techno-economically viable decision for building harbour, jetty or any other related structures. The seismic survey can assess all these parameters with the validation of a few boreholes from the respective areas. Though boreholes provide precise geological information at discrete locations, the procedure of drilling of boreholes in the sea is both times consuming and expensive. Further, the interpolation of geological information between two holes in a nearshore environment is not advisable as rapid variations in strata can occur within the shallow geological sequences. It is, therefore, desirable to undertake site-specific marine geophysical surveys and a limited number of borehole drilling to corroborate the findings. Though during the time of the survey, there was no such drilling information and there is a plan of developing port or harbour in the future, the seismic results can be corroborated with the borehole that would have been proposed at that time. Since the compressional (P-wave) and shear (S-wave) velocities along with density of different geological layers are the controlling factors for the assessment of geotechnical parameters and single-channel seismic reflection survey displays the vertical subsurface images in Two Way Time, it is little handicapped without borehole information for the depth and quality of different strata. The efficacy of the survey lies in the fact that it can reduce the number of boreholes and thus minimizes the cost and makes fewer hazards to the environment. It also reduces the lateral surprises that are sometimes encountered by nearby boreholes.
Civil Engineering