Calculation Method of Loosening Pressure for Deep-buried and Non-symmetry Closely-spaced Tunnels

Based on the Pu's sliding failure model of rock mass around a deep single tunnel, an analytical model of rock pressure for deep-buried and non-symmetry closely-spaced tunnels was proposed by considering asymmetrical structure and the construction processes. Meanwhile, based on the deduced formula, the causes that affect the rock pressure such as buried depth, rock pillars thickness, excavation span and excavation height were discussed. Finally, the comparison analysis was made between monitoring data from practical tunnel engineering and theoretical values from the model. The results show that the calculated model and the theoretical method proposed are rational and practicable. The experience and conclusions can be referred to the analysis of the design of supporting structure and reasonable construction scheme of deep-buried and non-symmetry closely-spaced tunnel.