Quantitative evaluation of borehole density impact on 3D geological modeling of quaternary structures

Accurate 3D geological modeling of Quaternary deposits is crucial due to their inherently heterogeneous structures, such as clay-silt lenses, channels, and slope deposits. These small- to medium-scale features significantly influence geological engineering and resource evaluation but are challenging to reconstruct with limited borehole data. In this study, a synthetic explicit 3D geological reference model containing typical Quaternary structures was constructed using GOCAD®. Borehole data were systematically extracted at varying densities using both regular and irregular sampling layouts and used to build implicit models through Leapfrog Geo™ software. Quantitative comparisons between the explicit and implicit models were conducted using Jaccard distance and normalized City-Block Distance metrics. The results demonstrate that as borehole density increases, the accuracy of the implicit models improves significantly, particularly in capturing small-scale structures such as lenses and narrow channels. Meanwhile, the influence of sampling layout remains comparatively minor. The study identifies a critical borehole density threshold required to reliably reconstruct complex geological features, providing quantitative measures for optimizing borehole exploration strategies in Quaternary geological settings.