Method for detecting hollow depth of concrete under steel shell

Abstract

The invention discloses a method for detecting the hollow depth of concrete under a steel shell. The method comprises the steps as follows: step 1, establishing a hollow depth calibration curve library: by changing hollow depth 1 between a steel plate and a concrete simulation standard block, thickness h of the steel plate and water content omega of the concrete simulation standard block, calibrating the hollow depth 1 by a thermal neutron detector to obtain the hollow depth calibration curve library, wherein the hollow depth calibration curve library comprises multiple hollow depth calibration curve units with different water contents, and each hollow depth calibration curve unit comprises three hollow calibration curves with different steel plate thicknesses; step 2, arranging detectionpoints; step 3, selecting and determining hollow depth calibration curves; step 4, measuring and determining the hollow depth. The hollow depth calibration curves are established, effects of water content of concrete on the hollow depth are fully considered, and different calibration curves are adopted for different steel plate thicknesses and water content of concrete, so that the detection of the hollow depth is more accurate and rapid.

Description

technical field [0001] The invention relates to the application field of radioisotope technology, in particular to a method for detecting void theorem between two heterogeneous media, steel shell and concrete. Background technique [0002] Large-scale hydropower and subsea tunnel projects often have some steel shell-concrete structures, such as pressure pipes of hydropower generating units, turbine volutes, runner chambers, nuclear power plant nuclear islands and large immersed tubes of subsea tunnels. When these concrete structures with steel plate lining are poured, due to the existence of the steel lining and the dense steel bars inside, the pouring construction is very inconvenient, the vibration is quite difficult, and the concrete is difficult to fill. Therefore, concrete and steel plates Void defects often exist between linings, which affect the safety and durability of structures. [0003] In view of this, it is necessary to use certain detection methods to detect t...

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Problems solved by technology

[0006] 1. The production cycle of the concrete slab module is long, such as after the pouring is completed, it needs to be placed for more than 28 days, etc., which will affect the calibration cycle

[0007] 2. After the production process and completion of the concrete slab module, the actual water content in the concrete slab module will change due to the influence of the ambient temperature and humidity at that time, resulting in a large deviation between the actual water content in the concrete slab module and the set water content

[0008] 3. A concrete slab module can only correspond to one water content. When the water content of concrete changes, a new concrete slab module needs to be made

In the patent application number 92112969.6, when calibrating the correlation curve between the cavity depth and the thermal neutron count rate, the variation of the void depth caused by the difference in concrete water content is not considered, so the calibration result is inaccurate

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