Reinforcement-Steel Fiber Concrete Shield Segment Normal Section Bearing Capacity and Reinforcement Determination Method

Abstract

The invention discloses a steel bar-steel fiber concrete shield segment normal section bearing capacity and reinforcement measuring method, which is characterized by taking an elastic flexural-tensileresidual strength value obtained through an open beam three-point bending test as a basic parameter of a material constitutive model, converting the elastic flexural-tensile residual strength obtained by the test into axial-tensile residual strength under a constitutive model; determining the axial force and the bending moment of the steel fiber reinforced concrete on the normal section of the shield segment according to the tensile strength and the stress distribution function of the steel fiber reinforced concrete; and then, considering steel bar configuration, establishing a steel bar-steel fiber concrete shield segment normal section ultimate bearing capacity balance equation set, and determining ultimate bearing capacity or steel bar configuration on the shield segment normal section. Therefore, the method not only can be used for determining the ultimate bearing capacity, but also can be used for determining the steel bar configuration, a steel bar-steel fiber reinforced concrete structure normal section bearing capacity measuring and calculating system is further perfected, and full exertion of the advantages of the steel bar-steel fiber reinforced concrete structure and application and popularization in other fields are facilitated.

Description

technical field [0001] The invention belongs to the technical field of tunnel engineering, and relates to the measurement of the bearing capacity of a shield tunnel segment in tunnel engineering, in particular to a method for measuring the bearing capacity of a front section of a shield tunnel segment and reinforcement in consideration of the post-crack strengthening and toughening mechanism of steel fiber concrete. Background technique [0002] The shield construction method is that the tunnel boring machine builds (lays) the "shield" (referring to the supporting segment) of the tunnel while driving. The lining of shield tunnels mostly adopts ordinary reinforced concrete segments. The reinforced concrete segments have reliable mechanical strength, good corrosion resistance, and mature construction technology. However, large steel consumption, low production efficiency, and It is prone to problems such as brittle failure and high local damage rate. The addition of steel fib...

AI Technical Summary

Problems solved by technology

Although the calculation method used in the code takes into account the strengthening effect of steel fiber on the bearing capacity of concrete, there are still the following problems: (1) The tensile strength value of steel fiber reinforced concrete in the code is mainly based on empirical parameters, and the constitutive model is consistent with the actual deviation, the calculation results are conservative and the accuracy is not high; (2) As a member of the ordinary reinforced concrete structure judged to be a large bias, after considering the tensile reinforcement of the steel fiber reinforced concrete, the tensile reinforcement cannot yield when the compression zone is damaged , become a de facto small eccentric component; the regulation considers the limited improvement of the bearing capacity of small eccentric compression components, so it is still calculated according to the current ordinary reinforced concrete structure regulations, ignoring the impact of the improvement of the tensile performance of the steel fiber reinforced concrete after cracking on the eccentric (3) The regulations do not set a limit value requirement for the height of the compression zone to ensure that the compression reinforcement reaches the compressive strength when the component fails

[0004] To sum up, there is currently a lack of an effective method for measuring the bearing capacity of the steel fiber reinforced concrete shield segments.

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