Strength of fabricated enclosed roadway support structure for TBM-excavated coal mine roadways: Experimental and numerical study

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An increasing number of tunnel boring machines (TBMs) had been successfully applied in underground coal mines in China in recent years. While The tunnelling speed of TBM-excavated roadways has been difficult to exceed 600 m/month in deep-buried underground coal mines, which is still slow compared with the TBM tunneling speed in traffic and water conservancy tunnels. The lesson learnt from the engineering applications suggests that the rockbolting is the main factor that delays the TBM tunnelling operations. This paper proposed a fabricated enclosed roadway support structure (FERSS) for TBM-excavated roadways. The full-scale model tests under uniform and non-uniform loading conditions were conducted. The strain distribution and deformation behaviors of models were studied by using both conventional monitoring technologies and new emerged photogrammetric deformation monitoring system. The deformations of the models are negligible throughout almost the whole tests. Near the end of the tests, the displacement of models increased dramatically and then the failure of models occurred immediately. The bearing capacity of models dropped significantly from 6454.09 kN to 3481.21 kN when the lateral coefficient increased from 1 to 2. Moreover, the numerical models of FERSS were established by ABAQUS software and numerical tests were implemented under various conditions thereby obtaining further data which cannot be acquired from experimental tests. The results of numerical tests are in good agreement with those of the experimental tests and the influence factors of FERSS bearing capacity were analyzed.