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The value of the formation resistance coefficient is very important for the design, construction and the long-term operational safety of the shield tunnel lining structure.In view of this, this paper first gives a summary analysis on the existing value methods of formation resistance coefficient in the load-structure analysis method of shield tunnel, and then according to the assumption of a simplified two-directional unequal stress field, a new modified formula of the formation resistance coefficient is proposed.Through the introduction of the correction factor ξ, this modified formula takes into account the influences of the load factors and the whole section distribution of formation resistance, and also makes up for the lack of the existing value methods which just using a single empirical value in the whole section and could be more reasonable reflect of the interaction between the surrounding strata and tunnel.Finally, the modified formula was used into the beam-spring model, and made a comparative analysis with the exiting formation resistance value methods.The results show that: axial force corresponding to the maximum positive and negative moments are little difference with the field test results;the segments positive moment results are greater than the measure values both in the Muir wood method and Plizzari-Tiberti method, however the results which used this modified formula have a small deviation with it, thereby the reasonableness of this modified formula is verified.The study results can provide an important basis for the reasonable value of formation resistance coefficient.