中文摘要：

基于传统稀释公式和前人推导的广义稀释公式存在的种种问题，在钻孔中存在垂向流的情况下，在合理的物理模型的基础上，考虑了渗透流速是示踪剂稀释时间的函数，重新推导了示踪方法测流速的稀释公式。通过3个公式的实例计算比较和误差分析，在钻孔中存在垂向流干扰时，孔中上下部垂向流速差得越大，新推导的公式与传统稀释公式计算出的渗透流速的相对误差越大，这一点与实际情况相吻合，因此新公式的计算结果更加可信。

英文摘要：

Owing to are some questions about the traditional dilution formula and the generalized dilution formula deduced by predecessors, a new dilution formula was derived to calculate seepage velocity with tracer method, based on the condition that there existed vertical flow in the borehole and a reasonable physical model was adopted, considering the seepage velocity as a function of tracer dilution time. When there was vertical flow in borehole, by the comparison between results of three formulas and the error analysis, it was shown that the greater the relative error of the seepage velocity calculated by the new deduced formula and traditional dilution formula was, the larger the difference of the vertical flow velocity of the borehole＇s upper and lower parts was, which was in accordance with the practical situation. So the results calculated by the new formula are more credible.