Seismic Based Geophysical Engineering Study of Jand Area for Site Characterization & Development of a Seismic Engineering Parameters Computation Software

Abstract

Geophysical Engineering is becoming more and more important due to the demand for construction of large civil infrastructure. The variations in the near surface layers need to be mapped before the construction of any heavy industrial zone or highway. In addition varying thicknesses and velocities of near-surface layers cause serious problems for seismic reflection imaging of the deeper subsurface. Seismic Refraction and Uphole Logging Survey is carried out in Jand area to map the near surface layers and estimate their velocities. This information is used to derive elastic properties, geophysical engineering properties and seismic characterization of the area. These properties give an estimate of the strength of Soil/Rock in the study area are used to identify suitable zones in the area for Civil Engineering works and construction of industrial sites. Contour maps of all important parameters; elastic moduli, soil amplification factor, soil fundamental period, allowable bearing pressure, standard penetration test, average horizontal spectral amplification are used for seismic characterization of the study area. In addition the near surface data is also used to compute Static corrections that can be applied to seismic reflection data for deep imaging of the Earth. The processing and interpretation of the data is performed on a highly interactive software, K-tron SeiRA along with Visual Oil Scripts and Surfer. As part of thesis work a Geophysical Engineering parameters computation software application has been developed, which efficiently computes all engineering and seismicity parameters from the near surface model and generates contour maps of any parameters on the fly. This application generates quick visualisation of all parameters for efficient interpretation and engineering decisions