RESEARCH ON THE MECHANICAL PROPERTY OF THE SURROUNDING ROCK OF DEEP-BURIED TUNNEL BASED ON THE ADVANCED REINFORCEMENT

In order to guarantee the stability of excavation face and surrounding rock in a construction process, ground reinforcement measures have been widely used, and how to properly evaluate the mechanical properties of the surrounding rock under the action of reinforcement is very important to tunnel design and to stability analysis. To investigate the mechanical behavior of tunnels under the effect of ground reinforcement, the deep buried circular tunnel is simplified as a plane strain model. The equivalent reinforced region is introduced to present the strengthening of ground mechanical property. Taking the ground reinforcement into consideration, a mechanical analytical model of tunnel surrounding rock is proposed. Based on the generalized Hoek-Brown yield criterion and non-associated flow rule, the displacement, stress and plastic zone radius of surrounding rock are derived in the presence of full-face type ground reinforcement, by analyzing the possible distribution of plastic zone. The validity and rationality of the method is verified by comparing with the in-situ measured value and numerical results, and the engineering significance of this formula in the design of support is further discussed by comparing with the traditional method. The results of the study show that the calculation results agree with the in-situ measured value and numerical results, and it is more advantageous than the traditional method in guiding the design of the support. The results of this paper better reflect the effect of ground reinforcement measures on the surrounding rock, providing a theoretical basis for the quantitative design of advanced reinforcement, thus providing a reference for tunnel design and safety evaluation under full-face reinforcement.