摘要
超声波在混凝土中的传播速度与混凝土的强度有关，而混凝土的强度与混凝土的龄期有直接关系。因此，利用超声波管法检测桩身质量，应以混凝土的28天龄期设计强度为依据。在天津永基花园工程中的超声波管法检测中，因桩身混凝土龄期变幅很大（3天～54天）．检测人员忽略了混凝士强度与龄期的关系，因而对25根桩做出了“不合格”的误判。后经用高、低应变法进行检测．合格率为100％。尤其对用超声被管法检测的9根“不合格”桩进行高应变测试，合格率为100％，优良率为89％，从而否定了超声波法的测试结果。
The propogation speed of ultrasound in concrete is related to the strength of concrete and the strength ofconcrete is directly related to the age of contrete. Therefore, the quality testing of the pile shaft by ultrasonictube methods shall be based on the design strength of 28-day gaes of concrete. The ultrasoic tube method wasapplied in Yongji Garden Project, Tianjin. With a significant varied range at the age of concrete (3 to 54days), the relations between the strength and the age of concrete was neglected, thus 'Unqualified' misjudgemen t for the 25 piles was made. Furthermore, the high and low strain testing were carried out. Throuth thetest, it was found that the qualified rate of the concrete piles reaches 100%. Especially for the unqualified 9 pilestested by the ultasonic insPecting, a high strain testing was conducted. The qualified rate of the concrete pilesreaches 100% and the sound rate is 89%. thus negating the test results by ultrasonic inspebtion.
关键词
超声波法
检测
钻孔灌注桩
混凝土龄期
桩身质量
ultrasonic inspection, testing, cast -in-situ piles, age of concrete, high strain testing, low strain testing
