Recently, a large number of borehole data created for public construction works have been available on the Web sites of the national/local governments as a machine-readable data. The purpose of this study is to develop a simple and easy method for constructing a voxel model which gives a good overview of the spatial distribution of geological information like lithofacies, to facilitate utilization of borehole data in geological analyses. In this paper, we have proposed a voxel modeling method of lithofacies on the basis of a large number of borehole data. The proposed method is designed to construct a voxel model with high-objectivity using lithofacies information stored in borehole data and Voronoi diagram calculated from locations of borehole data in a simple way. Test calculation to evaluate the proposed method was performed using about 3,100 borehole data in Setagaya area, Tokyo. In this test, we constructed a voxel model of lithofacies which has 8 categories and create its birds-eye view image and vertical/horizontal cross-section images. The results revealed that the voxel model gives a good overview of three-dimensional distribution of lithofacies. It is expected that the proposed method will improve efficiency of stratal correlation of borehole data in three-dimensional geological modeling.

A drawing error of Figure 2.3(c) in Shiono (2019) is corrected.