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岩溶是桥梁桩基施工中的安全隐患之一,探明桥梁范围内岩溶的空间分布特征对桥梁安全尤其重要。岩溶勘查目前多以钻探与物探方法相结合,但特定的岩溶勘察需要根据具体情况选择合适的物探方法,常用的地质雷达等方法由于受限于各自的适用范围,往往不能精确地确定局部范围内溶洞的边界。井间电磁波CT探测技术主要依据电磁波在不同介质中传播时的吸收差异,重建井间介质吸收系数的分布图像,形象而直观地展现地质体内部结构,具有分辨率高,勘探距离小的特点,特别适合于探测桥墩等局部范围内的溶洞分布情况。以惠州S119线水西大桥主桥墩溶洞探测为例,介绍了电磁波法CT探测技术的原理、工作方法及应用效果,结果表明井间电磁波CT探测技术有较高的精度和可信度,可全面清晰地揭示场地岩溶的空间分布,为工程设计提供可靠的地质资料。
Karst is one of the hidden dangers in the construction of bridge pile foundation. It is especially important to verify the spatial distribution of karst within the bridge. Currently, karst exploration is mostly combined with drilling and geophysical methods. However, specific karst exploration needs to select appropriate geophysical methods according to specific situations. Because of the limitation of their respective applicable ranges, commonly used methods such as geological radars often can not precisely determine the local scope Karst cave border. Crosswell electromagnetic CT detection technology mainly based on electromagnetic wave propagation in different media differences in absorption, reconstruction of crosswell absorption coefficient distribution image, and intuitively show the internal structure of geological bodies, with high resolution, low exploration distance characteristics, Particularly suitable for detecting the distribution of caves and other local cavities. Taking the detection of karst caves of the main pier of Shuixi Bridge in Huizhou, for example, the principle, working methods and application effects of the CT method of electromagnetic wave method are introduced. The results show that the CT detection technique of the electromagnetic waves between wells has high accuracy and reliability and can be fully Clearly reveal the spatial distribution of site karst and provide reliable geological data for engineering design.