岩石力学行为长期时效性是岩石工程领域及相关学科面临的重要挑战之一，利用仅仅持续几个小时到几个月的蠕变破坏试验来预测百年、千年或以上尺度的长期强度有着极大的不确定性。岩石的蠕变是对其内部微结构渐进演化的宏观响应，与常规短时试验中脆性岩石的裂纹发展有着相似的物理机制。结合3座古洞室群的花岗岩、凝灰岩和砂岩样本及一系列原位岩石破裂实例，本项目拟在实验室开展基于微结构演化和声发射观测的常规短时加载试验及特征应力分析、基于天-月-年尺度的恒载蠕变试验及长期强度测定、基于十年-百年尺度的长期强度反演及有关的精细数值模拟试验。结合其他来源的强度数据及长期强度下限阈值分析，从多个时间尺度揭示脆性岩石裂纹演化的物理本质及强度退化机制，建立脆性岩石长期强度的多时间尺度效应模型、千年及以上尺度的预测方法和公式。有关成果不仅可以核废料地质处置等岩石工程的长期稳定性评价提供依据，还有望推动岩石力学行为时效性的研究。

Long-term time dependency on mechanical behavior of rocks is one of major challenges in the field of rock engineering and relevant subjects. However,it is greatly uncertain to predict long-term strength of rocks on a hundred-year, thousand-year or longer time scales by means of creep failure tests of several hours to several months. Creep of rock is a macro-response to progressive evolution of its interior micro-structures, which has a mechanism similar to crack development in brittle rocks loaded during conventional short-term tests. Using granite, tuff and sandstone specimens from three ancient cavern groups and a series of rock rupture cases in situ, we will conduct the following studies, i.e., conventional short-term tests and characteristic stress analyses based micro-structure evolution and AE measurement, constant-load creep tests and long-term strength testing on different day-month-year scales, long-term strength back-analyses on 10-year and hundred-year scales, and relevant high-resolution numerical modeling. Combined with other strength data and lower limit threshold analyses, we will find physical essence of gradual crack evolutions, and strength degradation mechanism in/of brittle rocks on multiple time scales, establish multiple time-scale dependency model for long-term strength, prediction method and formulas on a thousand-year-scale or longer-scales. Relevant studies can not only provide basic data for long-term stability evaluation of rock engineering (e.g., underground disposal of nuclear waste), and potentially promote studies on time-dependent behaviors of brittle rocks.