A 3D Ubiquitous-Multiple-Joint Model and Its Application to the Stability Analysis of TBM Excavated Roadway in Jointed Stratum

Tunnel Boring Machines (TBMs) have been used in many underground coal mines in China with high constructive efficiency, sound equipment integration and low cost. A recent application of TBM in Yuandian No.2 Coal Mine in Huaibei, China, has shown that the surrounding rockmass spalled severely in stratum impacted by multiple joint sets. To analyze this problem, a new 3D ubiquitous-multiple-joint (UMJ) model was proposed in the present research, which comprised a rock matrix and multiple sets of joints according to geological conditions. Then, the yielding and deformation of the roadway excavated by TBM were analyzed. The results showed that the plastic zones, stress states and displacement of surrounding rockmass were significantly affected by the orientation of joint sets. The results could well indicate failure characteristics of the in-situ roadway and showed the advantages of UMJ model to simulate the excavation in jointed rockmass. The key factors influencing the roadway stability were discussed by the UMJ model. Based on the simulation results, suggestions on excavation-support schemes were proposed for TBM excavating roadways.