黏质土围岩分级指标的界限值确定

在分析了确定黏质土围岩分级指标界限值的依据基础上，通过分析已有研究成果资料、室内试验成果及长序列黏质土围岩统计数据，确定了设计阶段黏质土围岩的分级指标液性指数、天然密度、塑性指数分段的各段界限值。研究结果表明：依据分级指标随强度值比的变化情况确定其界限值是合理的；当隧道的埋深一定时，统计分析和室内试验都得到了强度值比随液性指数的增大逐渐减小的结论；液性指数较大时，天然密度的增大对强度值比的影响不明显；液性指数分段处界限值为0，0.25，0.5，天然密度分段处界限值为1.6，2.0 g/cm3，分级指标塑性指数分段处界限值为18。

Value limits of clayey surrounding rock classification indices

Through ascertaining the rule which is employed to obtain the value limits of clayey surrounding rock classification indices, value limits of liquid index, natural density and plastic index in design phase are made certain based on analyzing existing research results, a long sequence test data of clayey surrounding rock and test data. The research results show that it is reasonable to ascertain the value limits according to the different conditions of classification indices as intensity ratio changing. While the depth of the tunnel is constant, consistent result, which can be received through statistic analysis and testing, is that intensity ratio decreases with liquid index increasing. If the value of liquid index is larger, the influence of natural density increasing on intensity ratio is inapparent. The value limits of liquid indices are 0, 0.25, 0.5; and 1.6g/cm3, 2.0g/cm3 for natural density; 18 for plastic index, respectively.