Stability of the Čachtice Underground Corridors

At the beginning of the 16th century, the original inhabitants of Čachtice built a large complex of tunnels and cellars under the village, today called the Čachtice underground. The underground protected people from war conflicts, most recently during World War II, as anti-aircraft shelters. Over time, the underground lost its significance. The corridors were walled up, covered with rubble, and collapsed due to construction work. Later, a part of the underground was repaired, and historical events occurred in such a preserved part. Due to a lawsuit, the Čachtice underground was eventually closed to the public, and it was necessary to test the stability of the walls of the Čachtice underground. A 3D model of the underground was created, and three areas were identified in which numerical calculations were performed in Plaxis 2D software. The whole underground is located in loess soil. The Čachtice underground is stable if the conditions do not change diametrically. The calculated factors of safety support this assumption.