Natural Creation of Large Rock Cavern: Can We Construct Them? Jenolan Caves as a Case Study

The Jenolan Caves are the most spectacular limestone caves in Australia. Within this cave system, the Grand Arch, which is 24 m high, 55 m wide, and 127 m long, is the largest open cave in the country. A cave of this size could potentially accommodate small city streets, buildings, and other facilities. This paper examines a stability simulation of the Grand Arch, using numerical models to deduce foundational insights into rock openings under different geological and rock mass conditions. Following this, using numerical analysis, we investigate the creation of a man-made rock opening with the same span, height, and ground conditions of the Grand Arch but formed in two different arch shapes (i.e., with and without rock reinforcement as a stabilization measure). With all stability simulations conducted in this study, a clear explanation to describe the relationship and interaction between various parameters, such as rock mass structure and quality, rock mass strength, and in situ stress field, as well as different arch roofs shapes of the rock opening, is provided. Through its comparisons between natural rock cave and man-made rock openings, this study provides some findings and deep insight, as well as further questioning on creating a large size rock-reinforced cavern in different shapes to be opened in a range of rock conditions.