Fully-graded concrete stress-free strain measuring device and measuring method

Abstract

The invention relates to the field of concrete technical parameter measurement, and aims at solving the problem of low precision of the existing concrete strain measurement and providing a fully-graded concrete stress-free strain measuring device and measuring method. The fully-graded concrete stress-free strain measuring method comprises the following steps of preserving a cylindrical pit with the bottom surface diameter being D and the depth being L in a concrete dam construction cabin surface; after the final setting of peripheral concrete, putting a stress-free barrel into the pit; installing a strain meter into an inner cavity of the stress-free barrel; casting fully-graded concrete into an inner cavity of the stress-free barrel, wherein the casting height h1 is smaller than the depthL1 of an inner cavity of the stress-free barrel; after the initial setting of the concrete in the stress-free barrel, taking the initial value of the strain meter; casting a next cabin of concrete; covering the stress-free barrel; continuously monitoring the strain meter value; analyzing the stress-free strain of the fully-graded concrete. The device and the method provided by the invention havethe beneficial effects that the external stress influence can be enabled to be effectively avoided or possibly reduced, so that the measuring value of the strain meter is sufficiently accurate.

Description

technical field [0001] The invention relates to the field of concrete technical parameter measurement, in particular to a fully graded concrete stress-free strain measuring device and a measuring method. Background technique [0002] At present, the common method of measuring the stress-free strain of dam concrete is used to cooperate with the strain gauge group to measure the stress state inside the dam. Since the installation accuracy of the strain gage group is easily disturbed, it is not suitable to fill fully graded concrete nearby. Therefore, wet screen secondary grade concrete is filled in the non-stress gauge bucket and near the strain gage group. [0003] However, the current simulation analysis and temperature control of dam concrete temperature stress rely on material parameters such as linear expansion coefficient and autogenous volume deformation obtained from stress-free measurement. Because the non-stress gauge bucket is filled with wet-screened secondary gra...

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Problems solved by technology

As the non-stress gauge bucket is filled with wet screened secondary grade concrete, the measured material parameters cannot reflect the true characteristics of the fully graded concrete in the dam

[0004] On the other hand, simply scaling up the size of existing unstressed strain measurement devices does not solve the problem

Because, ① the existing non-stress meter barrel is a double-layer thin iron barrel, and there is a gap between the double layers to isolate the interference of the external stress of the barrel, but the barrel body is easily buckled by lateral extrusion, resulting in the loss of the stress-free environment. After the size is enlarged, the possibility of buckling during the installation and vibration process also increases; ②The gauge length of the strain gauge used in the existing stress-free strain measurement is small, and the measured value is easily affected by the large particle size The impact of the spatial distribution of aggregates; ③The existing fixation method of the strain gauge is relatively simple. The strain gauge is fixed on the central axis of the barrel by iron wire. When grading concrete, it needs to be vibrated and shaped, and the position of the strain gauge is easily disturbed

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