Strain Measurement and Load Back Calculation Method of Tunnel Secondary Lining Based on Stress Relief Method

Abstract

The invention relates to a method for measuring the strain of the secondary lining of a tunnel and back-calculating the load based on the stress relief method. The strain gauge is pasted at the position to be detected, and the initial value of the strain is read through the strain gauge; Then use the cutting machine to cut and groov the concrete along the scribed line; 15 minutes after the grooving is completed, read the reading of the strain gauge for the second time to obtain the surface strain value of the secondary lining; then theoretically calculate In the load-surface strain curve of Average the final load value and take it as the load value of the secondary lining. The method of the invention is simple in implementation and fast in efficiency, can determine the load-bearing state of the secondary lining of the tunnel, and provides a basis for evaluating the safety of the tunnel.

Description

technical field [0001] The invention relates to a method for strain measurement and load back calculation of the second lining of a tunnel based on a stress relief method. Background technique [0002] A key issue in evaluating the safety of the lining structure of highway or railway tunnel is to accurately determine the actual load of the secondary lining. However, due to the following two reasons, the load of the second lining cannot be accurately determined. The first one is that the surrounding rock has a certain self-stabilization ability, and the self-stabilization ability of the surrounding rock has been further improved through bolt reinforcement, grouting and other measures, resulting in the actual pressure on the second lining being far less than the design load; the other is that the construction During the process, there may be defects or diseases such as insufficient thickness of the local lining, insufficient strength to reach the design value, and excessive s...

AI Technical Summary

Problems solved by technology

However, due to the following two reasons, the load of the second lining cannot be accurately determined

The first one is that the surrounding rock has a certain self-stabilization ability, and the self-stabilization ability of the surrounding rock has been further improved through bolt reinforcement, grouting and other measures, resulting in the actual pressure on the second lining being much smaller than the design load; the other is due to the construction In the process, there may be defects or diseases such as insufficient thickness of the local lining, insufficient strength to reach the design value, and excessive spacing of the second lining steel bars. In addition, sensors are not pre-embedded in the construction of the second lining under normal circumstances, so the actual stress state of the second lining and The load situation cannot be accurately evaluated

At present, experts and scholars at home and abroad mostly inversely calculate the tunnel load and surrounding rock pressure based on a large amount of measured displacement data. Load and surrounding rock pressure are particularly difficult

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