Using the Grid-Characteristic Method to Investigate Parameters of the Geological Environment in the Vicinity of a Tunnel

The construction of underground structures, such as tunnels, requires thorough preparation and research to ensure the safety of work. During such operations, problems can arise related to the presence of various geological heterogeneities near the work site. Various methods for predicting the presence of these geological heterogeneities near the ongoing work can be used to detect them. The development and advancement of such methods and approaches is an important task. One approach that facilitates the development of these technologies is numerical modeling, i.e., solving the direct problem of seismic exploration. This article discusses the application of the grid-characteristic method for the numerical modeling of seismic wave propagation in complex geological environments in the vicinity of a tunnel, with the aim of detecting geological heterogeneities. The proposed grid-characteristic method demonstrates advantages due to its combination of computational efficiency, ability to handle complex geometry, and accurate accounting of material interfaces. The work includes verification of the method based on a field experiment of seismic investigation near a tunnel under construction. Numerical experiments were conducted for three scenarios: without a geological feature, with a fault, and with a water-saturated layer. Wave fields and probability maps of heterogeneity boundaries were constructed. The results showed qualitative agreement with real seismograms and confirmed the possibility of detecting geological features ahead of the tunnel face.