考虑高地温及其梯度影响的围岩分级方法初探

工程岩体分级是岩石力学及其工程应用研究的最基本内容之一,当前岩体分级体系中尚无考虑高地温及高温度梯度等复杂地质环境下的围岩分级方法。依托南疆某水电站高温洞段引水隧洞工程建设,基于现场地质描绘、现场钻孔测试及室内岩石力学试验成果,采用RMR、GSI、BQ和HC等不同分级体系对高温洞段开展岩体质量评价;最后根据实际围岩级别与定性和定量分级结果对比分析,提出了高地热下围岩类别影响因子及阈值指标,给出了高地热赋存环境状态对围岩分级的修正方法,在此基础上提出适用于高地温梯度环境下的隧洞围岩质量分级与评价方法。研究表明,考虑了温度修正后,各类围岩的岩体质量评价结果相对传统方法减小1/4~1/2级,与实际定级结果更为接近,提高了分级的准确率。研究结果对于存在高地温的隧洞围岩分级有参考价值。

Preliminary Discussion on Classifying Surrounding RockmassConsidering Influence of High Ground Temperature andGeothermal Gradient

The classification of engineering rockmass is a most basic content in rock mechanics and rock engineering application research area. However, current applied rockmass classification system doesn’t cover the rockmass classification method for surrounding rockmass under special geological conditions, such as high ground temperature and high temperature gradient. On background of a hydropower station construction in south Xinjiang, a segment of diversion tunnel with high ground temperature is chosen for surrounding rockmass classification research. On the basis of field geological mapping, in-situ acoustic test and laboratory rock mechanics test results, the RMR, GSI, BQ and HC systems are applied respectively to the rockmass classification and rockmass quality evaluation for the research segment. According to actual surrounding rockmass grade as well as qualitative and quantitative grading results, the influence factors and threshold indexes of high ground temperature are proposed. The evaluation method of surrounding rock quality method of tunnel under complex geological conditions is obtained. Results show that the rockmass quality evaluation grade results with the proposed method are reduced by 1/4~1/2 grade, much closer to the actual grading results.