Usually, the operating parameters and performance parameters of tunnel boring machines show a significant relationship with the geological conditions of the tunnel route. This relationship is the basis of many empirical relationships and models for predicting the performance of the machine. By knowing the geological conditions of the tunnel route, an estimate of how the machine will perform can be obtained using these models. Obviously, conversely, by knowing the actual performance parameters of the machine in a drilled tunnel, the geological conditions of the tunnel route can also be indirectly determined to some extent. This can be very useful for understanding the characteristics of the excavated ground, especially in tunnels that are excavated using shielded tunnel boring machines. In this article, considering the uncertainties that exist, especially regarding the location of the active Pourkan-Verdij fault in the Karaj water transfer tunnel route (second segment), an attempt has been made to indirectly interpret the geological conditions of the tunnel route in the area around the fault and determine the thickness and location of the fault zone by using some indicators, including operator parameters and parameters related to machine performance.