Method for testing stress and deformation of concrete inner wall of vertical shaft based on concrete conductivity

Abstract

The invention discloses a method for testing stress and deformation of a concrete inner well wall of a vertical shaft based on concrete conductivity. The method is suitable for nondestructive stress and deformation testing of the concrete inner well wall of a newly-built well. Short carbon fibers are added into the vertical shaft concrete inner shaft wall at the position where the vertical shaft concrete inner shaft wall bears large stress and is commonly damaged, so that the local vertical shaft concrete inner shaft wall has the conductivity characteristic and the self-sensing stress characteristic. Based on the principle that compressive deformation resistance changes remarkably, a specially designed scanning test circuit and a wireless transmission technology are adopted, and nondestructive online diagnosis and detection on the stress condition and damage degree of the inner wall of vertical shaft concrete are achieved. The technology changes the passive and point test uncertainty of the original test technology, reduces the test error, can improve the tensile and flexural properties of the concrete by adding the carbon fiber, does not reduce the strength and safety of the inner well wall, and has the advantages of simple construction, high cost performance, high test precision and the like.

Description

technical field [0001] The invention relates to a method for testing the stress and deformation of the concrete inner shaft wall of a vertical shaft based on the electrical conductivity of the concrete, and is especially suitable for establishing a non-destructive test of the stress and deformation of the inner shaft wall of the shaft concrete. Background technique [0002] The shaft shaft is the most critical part of coal mine production, and its safety and stability are the prerequisites for ensuring the safe production of the entire coal mine. However, when the vertical shaft passes through complex and special strata, it is difficult to accurately and reasonably determine the load on the shaft wall. As the depth of the stratum increases, the design thickness of the shaft wall continues to increase according to the "Coal Mine Shaft Shaft and Chamber Design Code" (GB50384-2016). The construction cost, construction difficulty and potential safety hazards of the vertical shaf...

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Problems solved by technology

[0004] (1) Surface strain gauges are installed on the inner surface of the shaft shaft: this scheme has little disturbance to the shaft wall, and can obtain the deformation and stress of the inner surface of the shaft shaft wall, but limited by the number of measuring points, only the deformation and stress of local points can be obtained. However, it is still necessary to use a simplified mathematical model to invert the stress on the wellbore wall, and such surface strain gauges are mostly installed on relatively intact wellbore walls, which have poor reliability in estimating the load on the wellbore wall that has been ruptured or after the rupture. ;

[0005] (2) Strain gauges are installed inside the shaft wall: This scheme has a large disturbance to the shaft wall, and can obtain the three-dimensional deformation and stress state of the shaft wall, but it is also limited by the insufficient number of measuring points and the limitation of the installation location. and the accuracy of the evaluation of the wall load after the fracture is poor;

[0006] (3) Direct test of vertical shaft wall water and soil pressure: only applicable to newly built shafts. During the construction period, earth pressure gauges and water pressure gauges are buried between the shaft wall and surrounding rock to directly test the water and soil pressure of the vertical shaft concrete inner shaft wall. It is the most direct test method, but because most of the double-layer shaft wall construction schemes adopt the freezing method, it is difficult to obtain the test data of the sensors during the construction period, and the sensors cannot be repaired afterwards. optimization

[0007] To sum up, the traditional test schemes either cannot directly test the stress state of the vertical wellbore, or the test method has a large disturbance to the vertical wellbore, or it is difficult to obtain the test data of the whole life cycle due to manual conditions. At present, there is an urgent need for a comprehensive Azimuth non-destructive testing scheme for shaft concrete inner shaft wall stress condition

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