A tunnel floor lining concrete temperature control anti-cracking tensile stress K value control design method

Abstract

The invention provides a tunnel bottom plate lining concrete temperature control anti-cracking tensile stress K value control design method. The method comprises the following steps of 1, collecting the data for tunnel bottom plate lining concrete temperature control anti-cracking calculation; step 2, analyzing and determining a temperature control anti-cracking target and an anti-cracking safetycoefficient allowable value K; step 3, designing a temperature control anti-cracking measure scheme, analyzing the variables, and formulating a plurality of lining concrete temperature control anti-cracking construction measure schemes; substituting each proposed temperature control measure scheme into formulas 1 and 2 for calculation to obtain tensile stress omega 1 and omega 2 when the minimum anti-cracking safety factor Kmin of each scheme in the early stage and winter of the concrete construction period occurs; calculating the age d1 and the age d2 of each scheme at the early stage and inthe case of Kmin in winter; step 3-4, calculating the minimum anti-cracking safety factor Kmin of the lining concrete during the construction period of each scheme; step 3-5, under the condition thatKmin is greater than or equal to K, optimally selecting a measure scheme for construction application according to a simple, practical and economic principle.

Description

technical field [0001] The invention belongs to the technical field of temperature control and anti-cracking of engineering structures, and in particular relates to a control design method for the temperature-controlled anti-cracking tensile stress K value (safety factor) of concrete lining the floor of a city gate tunnel. Background technique [0002] Cracks are one of the main diseases of concrete. According to the dominant cause of cracks, it can be divided into two categories: structural cracks caused by external loads and non-structural cracks caused by deformation changes. Deformation effects include temperature, drying shrinkage and wet expansion, and deformation of surrounding rock, among which 80% are temperature cracks. In recent years, with the rapid development of water conservancy and hydropower engineering construction, the scale and section size of underground hydraulic engineering have become larger and larger, and the environmental conditions such as geolog...

AI Technical Summary

Problems solved by technology

In doing so, firstly, the temperature control standard for dam concrete cannot be applied to the thin-walled lining structure, and does not reflect the influence of differences in concrete strength, surrounding rock performance, lining thickness, and structural scale; secondly, the construction unit calculates the maximum temperature inside the lining concrete. Large, a large number of coefficient values ​​are highly artificial; the temperature difference between the two aspects may lead to a large distance between the formulated construction plans, and the target of temperature crack control cannot be effectively achieved

In particular, the analytical temperature stress is not calculated

[0007] Based on the above situation, at present, there are no clear requirements and technical standards for temperature control and crack prevention of lining concrete in underground engineering construction; there is no simple and high-precision design method, and the finite element method is time-consuming and expensive, and cannot be applied without concrete test results. The preliminary design stage and the rapid adjustment of the construction plan; the strong constraint method has a large error, and the temperature stress cannot be calculated; it is difficult to quickly and effectively achieve the temperature crack control target

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