Spatial Variability of Depth to Weathered Rock for Chennai Using Geostatistical Kriging

The objective of this study is to evaluate the spatial variability of depth to weathered rock in Chennai city using field test data. The database consists of nearly 400 borehole data covering the entire city with stratigraphic information and the same is used in the study. Ordinary kriging technique, which uses the spatial correlation of the data, is applied to estimate the depth at locations where the field measurements are not available. In addition, the variance of the estimated data is also computed. The developed map indicates that the depth to weathered rock in the study area varies from 3 to 30 m from the ground level. The estimated depths to weathered rock are compared and validated with a few selected borehole data and Multichannel Analysis of Surface Wave (MASW) test results. These maps can be used in the ground response analysis, foundation analysis, and design studies.