Physical overloading test for 3D printed caverns: Failure performance and supporting effect

Abstract

Excavation of a large underground cavern often induces the unstable behavior of the surrounding rock due to intensive stress redistribution; thus, reasonable supporting measurements are necessary. A new 3D print-based physical overloading test method is presented for exposing the failure performance of caverns and the reinforcing effect of supported structures. Taking the Yingliangbao underground caverns as an engineering background, a physical model and supporting elements for the cavern groups are manufactured first by 3D printing (3DP) technology, including a multi-cavern 3DP sand model, 3DP polymer lining and metal bolt. Further overloading tests for the printed physical models are carried out, and the progressive failure performances are exposed, including crack extension, model loading evolution, local strain development, etc., which indicate that shear failure often appears on the mid-wall. Moreover, the overloading test for the supported cavern model also quantitatively reveals the reinforcing role of the 3DP polymer lining and metal bolt, such as increasing the bearing capacity by more than 10%. A corresponding numerical back analysis is further applied to certify the progressive failure process of multiple caverns under overloading conditions, which provides some cures for the supported bolt position and depth in multiple caverns. This method can enrich the physical model test and guide the support design for underground engineering construction.