声波透射法首先是当混凝土内部存在缺陷时，在超声波发一收通路上形成了不连续介质，低频超声波将绕过缺陷向前传播，在探测距离内，其绕射到达所需的“声时"比超声波在无缺陷的混凝土中直接传播时所需的“声时"长，反映出超声波的声速减小。其次是由于存在缺在缺陷时，超声波在混凝土中传播时声能衰减加大，接收信号的首波幅度下降。第三是由于混凝土存在缺陷时，高频成分比低频成分消失快，接收信号的频率总是比通过相同测距的无缺陷混凝土接收到的频率低。最后，由于超声波在缺陷界面上的复杂反射、折射，使声波传播的相位发生差异，叠加的结果导致接收信号的波形发生畸变。据此即可对混凝土内部的质量情况作出判断。
检测要点
1、预埋检测管：
（1）桩径0.6-0.8m应埋设双管；桩径0.8-2.0m应埋设三根管；桩径2.0m以上应埋设四根管，根据赤峰桥具体情况，桩基可埋设三根管。
（2）声波检测管宜采用钢管、塑料管或钢质波纹管，其内径宜为50～60mm。检测管连接处应光滑过渡，管口应高出桩顶100mm以上，且各声测管管口高度应一致，管的下端应封闭，上端应加盖，管内不得有异物，管身不得有破损。
（3）检测管可焊接或捆扎在钢筋的内侧，检测管之间应互相平行。
（4）在检测管内应注满清水。
2、现场检测
（1）现场检测前测定声波监测仪发射至接受系统的延迟时间t。并计算声时修正值。
（2）测量时发射与接收探头应以相同标高或保持固定高差同步升降。
（3）测量点距为40cm，当发现异常时再加密到20cm.
（4 ）选择适当的发射电压和放大器增益，并再测试过程中保持不变。
（5）实时显示和记录接收信号的时程曲线。
（6）将多根声测管以两根为一个检测剖面进行全组合，分别对多有剖面完成检测。
（7）每组检测管测试完成后，测试点应随机重复抽测10％，其声时相对标准差不应大于5％；波幅相对标准差不应大于10％。

Sound wave transmission method is first when the internal defects of concrete on the ultrasonic hair a closed path formed the discontinuous medium, low frequency ultrasonic transmission, routing around the defects will forward within the detection range, the diffraction reached the required "sound" than the direct spread of ultrasound in zero defect of concrete when the "sound", reflect the ultrasonic sound velocity decreases. Second is due to the lack of the defect, the ultrasonic propagation in concrete acoustic energy attenuation, receiving signal amplitude of the first wave. Third is due to the defect of concrete, the high frequency component is faster than low frequency components disappeared, the frequency of the received signal is always better than by the same range of defects in concrete the received frequency is low. Finally, due to the complexity of ultrasonic wave on the interface defect of reflection, refraction, differences in the phase of sound wave propagation, the result of superposition leads to the distortion of the received signal waveform. This can be a judgment about the quality of the concrete internal situation.
Test points
1, embed test:
(1) diameter 0.6 0.8 m should be embedding double tube; Diameter 0.8 2.0 m should be buried three root canal; Diameter 2.0 m above four root canal should be buried, according to the specific situation, chifeng bridge pile foundation can be buried three root canal.
(2) the acoustic detection tube appropriate USES steel pipe, plastic pipe, or steel corrugated pipe, the inner diameter should be 50 ~ 60 mm. Detection of pipe joint should be smooth transition, nozzle should be 100 mm or more above the pile top, and the test tube mouth height should be consistent, the lower end of the pipe should be closed, shall be affixed to the top, the tube can not have a foreign body, the play shall not be damaged.
(3) the test tube can be welded or tied reinforcement on the inside, between the test tube should be parallel to each other.
(4) in the test tube should be fresh water injection.
2, field testing
(1) the testing before the determination of acoustic monitor is the transmission and reception system delay time t. The sound and calculate the revised.
(2) the transmitting and receiving probe measurement should be in the same level or maintaining a constant altitude difference synchronization lifting.
(3) the measurement point to 40 cm, when found abnormal encryption to 20 cm.
(4) select the appropriate voltage and amplifier gain, and remains unchanged during the process of test again.
(5) the time history curve of real-time display and record the received signal.
(6) will be more acoustic detection tube for two root for all combinations, a test profile is section for more complete detection respectively.
(7) after completion of each group of test tube test, the test point should be repeated random parking 10%, relative standard deviation shall not be more than 5% when the sound; Amplitude relative standard deviation shall not be more than 10%.