Tunnel secondary lining strain measurement and load back calculation method based on stress relieving method

Abstract

The invention relates to a tunnel secondary lining strain measurement and load back calculation method based on a stress relieving method. A strain gauge is attached to a position to be detected, andan initial strain value is read by the strain gauge; then, scribing is conducted on a selected part of the surface of a tunnel in the length direction of the tunnel, and afterwards, a cutting machineis used for cutting and slotting concrete along the scribing part; 15 minutes after slotting is completed, secondary number reading is conducted through the strain gauge to obtain a secondary lining surface strain value; then the load bearing value of a secondary lining is marked according to the secondary lining surface strain value of each reference point in a theoretically-calculated load-surface strain curve; each reference point is separately compared to remove failure data, and effective data is averaged to obtain a final load value to serve as the secondary lining load bearing value. The method is easy to implement and high in efficiency, the load bearing state of the secondary lining of the tunnel can be determined, and a basis is provided 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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