To confirm the robustness of a tunnel, the quality of the rock mass is usually evaluated by several rock mass classification (RMC) systems before its design. Besides, the accuracy of the RMC should be checked through the correlations between different RMC systems. The relationship between the different RMC systems and P-wave velocity indexes is conducive to the interpretation of the rock mass. Here, based on linear or nonlinear regression analysis of 231 samples, we established the RMR–Q, [BQ]–Q, and [BQ]–RMR relationships with R² = 0.935, 0.732, and 0.759, respectively. Further analysis showed that the grading differences between any two RMC systems yield different characteristics when the rock mass score is at different intervals. To evaluate the relations between RMC indexes and P-wave velocity, we conducted a group study on the different grading differences among RMR, Q, or BQ. Depending on the consistency of the grading results, we arranged the values from large to small as the amplitude of the slope of the curve, and the grading results differed by either one or two levels. Our data demonstrated that the grading differences between the systems are proportional to the discontinuous state of rock mass in the classification. In addition, the classification results of Q, RMR, and BQ showed more significant differences when less consideration is given to the integrity of the rock mass.

为了确定隧道的坚固性，通常在设计之前通过几种岩体分类（RMC）系统来评估岩体的质量。此外，RMC的准确性应通过不同RMC系统之间的相关性进行检查。不同的RMC系统与纵波速度指标之间的关系有利于岩体的解释。在此，根据231个样本的线性或非线性回归分析，我们建立了RMR– Q，[BQ] –Q和[BQ] –RMR与R ^2的关系。 分别为0.935、0.732和0.759。进一步的分析表明，当岩石质量得分处于不同的区间时，任意两个RMC系统之间的坡度差异会产生不同的特征。为了评估RMC指标与P波速度之间的关系，我们对RMR，Q或BQ之间的不同坡度差异进行了小组研究。根据定级结果的一致性，我们将值的大小从大到小排列为曲线斜率的幅度，并且定级结果相差一两个级别。我们的数据表明，在分类中，系统之间的等级差异与岩体的不连续状态成正比。另外，Q的分类结果较少考虑岩体的完整性时，RMR和BQ表现出更大的差异。