Study on calculation method of tunnel earth pressure considering expanding arch effect postprint

Abstract: In the process of tunnel excavation, considering the form of tunnel potential slip surface, combined with the development law of stratum arch effect, a triangular slip surface model with comprehensive consideration of expanded arch effect is proposed, and the tunnel earth pressure under the limit equilibrium condition is deduced and calculated by using this model. Through an example, the influence of the model parameters, such as cohesion reduction coefficient, sliding surface friction angle and slip surface camber angle, on the earth pressure calculated by the model is compared and analyzed, and various limit equilibrium theory tunnel earth pressure analysis is carried out to verify the applicability of the calculation model. The results show that the smaller the cohesion reduction coefficient, the greater the earth pressure calculated by the model. The smaller the friction angle of sliding surface, the greater the earth pressure calculated by the model; The greater the camber of slip surface, the smaller the calculated earth pressure will be. With the increase of depth, the earth pressure first increases and then decreases. In this model method, the selection of cohesion reduction coefficient plays a decisive role in the calculation of tunnel earth pressure, and the earth pressure calculated by selecting cohesion reduction coefficient =0.2 is similar to that calculated by other theories, which is more applicable. At the same time, combined with the analysis of the limitations and applicable critical depth of various kinds of loose earth pressures, according to the use conditions and influencing factors of various kinds of earth pressures, the appropriate calculation method is selected, which provides a basis for accurate calculation of tunnel earth pressures.