Thickness Measurement of Concrete Structures by Radar Detector
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摘要: 为了得到混凝土结构的厚度，采用了探地雷达技术进行检测。介绍了探地雷达的检测原理，由发射天线向混凝土结构发射高频脉冲电磁波(1 MHz~2 GHz)，电磁波在其中传播时，其传播路径、电磁场强度和波形将随所通过介质的电磁属性(介电常数)和几何形态的变化而变化。雷达主机将接收此部分的反射波，并根据其双程传播时间t和计算所得速度v计算出各结构层的厚度。通过采用RIS-2K型探地雷达配置1 600 MHz天线，对阶梯试件厚度的检测，发现在厚度<400 mm时，检测最大误差为6.7%。实际的桥梁混凝土检测发现，该技术对120 mm左右的现浇混凝土板的变异系数为4.5%，而钢筋保护层厚度和钢筋间距的变异系数较大，说明后两者的均匀性较差。试验证明，采用雷达法检测混凝土结构的厚度是切实可行的。Abstract: In order to measure the thickness of concrete structures, ground penetrating radar technology was used. The detection theory of ground penetrating radar was introduced. The system applied transmission antennas to launch high-frequency pulse electromagnetic wave(1 MHz~2 GHz) to the concrete structure, and while spreading along the path, its strength and waveforms would be adopted as the medium of electromagnetic property(dielectric constant) and the geometry. The main machine of Radar would receive the reflected wave, and in accordance with its double-layer propagation time t and calculated speed v to calculate the thickness of the layer structure. Through the thickness measurement of samples, the testing results showed that with thickness <400 mm, the detection maximum error was 6.7%. The on-site concrete bridge testing found that, for 120mm concrete slab cast-in-place, the standard measuring error was 5.29 mm, while for reinforced protective layer thickness and reinforcement of the larger spacing, the standard measuring error was much higher, which illustrated the less uniformity of the latter two. Testing results proved that it was practicable to measuring the thickness of concrete structures by Radar.
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