FAILURE MECHANISM AND SCOPE PREDICTION MODEL OF HORIZONTAL INTERBEDDED SURROUNDING ROCK TUNNEL

Due to the remarkable bedding structure of horizontal interbedded surrounding rock, the failure form of horizontal interbedded surrounding rock is quite different from that of homogeneous surrounding rock. The current research on horizontal interbedded surrounding rock focuses on a single failure mode, without considering the diversity of failure modes. In order to explore the failure area of horizontal interbedded surrounding rock, firstly, it is divided into single-layer surrounding rock to analysis according to its bedding plane. The horizontal interbedded surrounding rock failure is divided into three typical failure modes: tensile failure, shear failure at wedge boundary and shear failure at arch boundary. The rock beam-tension analysis model and the arch key block-shear analysis model are established respectively to analysis the failure of single-layer surrounding rock, and the corresponding failure criteria are proposed. And use the slump coefficient and critical height to study the division conditions of different failure modes. This method is applied to mine channel and tunnel engineering examples, and compared with the existing methods to verify the reliability of the failure mechanism model of single-layer surrounding rock. At the same time, it is substituted into the example of abscission damage calculation to verify the practicability of the failure mechanism model of single-layer surrounding rock. Based on this, a horizontal interbedded surrounding rock failure model is established by combining the interlayer continuous conditions and the failure rest conditions of the failure range. The above horizontal interbedded surrounding rock failure model is applied to the example of Bulianta mine roadway, and the results show that the horizontal interbedded surrounding rock failure range predicted by this method is in good agreement with the numerical simulation results and the actual collapse situation. The research achievements can provide a theoretical basis for the design of support scheme of tunnel in horizontal interbedded surrounding rock.