水库大坝渗水问题一直是工程建设中的难题,尤其是大坝蓄水后,渗漏现象处理较为困难。常规的高密度电法、探地雷达等无损检测手段受到场地或干扰条件限制,很难准确发现渗漏具体位置和规模。引入跨孔超声波透射技术对大坝裂隙进行探测,将获取的声波初至走时进行拾取,利用网格射线获取大坝介质内部波速结构,结合PSD(Power Spectral Density)判别法判断大坝裂缝发育的具体位置和规模。研究结果表明:跨孔声波法透射成像技术能获取较高的分辨率,精细探测水库大坝坝肩裂隙发育状态,探测结果与钻孔取芯资料高度吻合。该方法的成功引入为水库大坝渗漏检测提供了行之有效的新手段,其探测成果不仅可为大中型水库大坝渗漏处理提供检测依据,还可为水库大坝风险后果综合评价提供参考,具有较高的推广应用价值。

The seepage of reservoir dam has always been a difficult problem in engineering construction, especially after the impoundment of dam. Limited by site or interference conditions, conventional nondestructive testing methods such as high-density electrical method and ground penetrating radar could not easily find the specific location and scale of leakage accurately. In this paper, the cross-hole ultrasonic transmission technology is introduced to detect the cracks in a dam. The first-break travel time of the obtained sound wave is picked up, and the wave velocity structure in the dam medium is obtained by using grid ray. The specific location and scale of dam cracks are determined with PSD (power spectrum density) discriminant method. The research results demonstrate that the cross-hole acoustic transmission imaging technology could detect the fracture development state of dam abutment by obtaining high resolution images. The detection results are highly consistent with the drilling data. In conclusion, it is proved to be an effective method for detecting reservoir dam leakage. The detection results offer detection basis for the treatment of leakage in large and medium-sized reservoir dam, and also provide reference for comprehensive assessment of reservoir dam risk consequences.