基于超声脉冲法的火灾损伤后混凝土裂纹深度检测

Measurement of Concrete Crack Depth after Fire Based on Ultrasonic Impulse Method

检测或诊断裂纹深度是火灾后混凝土结构受损综合评判的重要依据。开发一种专用的火灾后混凝土裂纹深度检测仪器,是一项填补国内该领域空白的重要研究课题。在研讨和分析超声脉冲法检测混凝土表面损伤裂纹深度的单面平测法、逐层穿透法和损伤层厚度判定3种测试方法的基础上,笔者设计开发了一种超声测试诊断仪,采用高精度计时电路、传感器驱动电路和自动增益电路,提高了仪器计时精度和抗干扰性。经对多组火灾损伤后的结构混凝土试件的测试,获取了6组共60个声时数据,用给出的方法进行了计算,得出的裂纹深度值与观察结果能较好地吻合。理论与实测表明,提出的裂纹检测方法和开发出的测试仪器具有实用性。

To test or diagnose the depth of crack is the important basis of integrated judgment of damaged concrete structure after fire. k is a significant task to develop a special inset for concrete crack depth test after fire. Three kinds of testing methods based on ultrasonic impulse such as single surface flat measurement, measurement by penetrating through every layer and depth determination of the damage layer are introduced. An ultrasonic diagnose instrument is developed by using high precision timing circuit, sensor driving circuit and automated gain circuit. The precision and anti - interference character has been enhanced in the instrument. 60 sound-time data of 6 groups are obtained and calculated by the method after many times of testing of the concrete structure, The results are basically consistent with the observed data. The crack depth test method and the instrument presented are testified to have fine practicability.