结构面长期强度确定方法对比研究∗

结构面长期强度的确定对工程岩体长期安全稳定性评价具有重要意义。在对水泥砂浆结构面试件分别进行了不同法向应力条件的剪切应力分级剪切蠕变试验和循环剪切应力松弛试验的基础上,分别利用过渡蠕变法、应力-应变等时曲线法和应力松弛法对结构面的长期强度进行了求解。结果表明:过渡蠕变法确定的长期强度精度依赖于蠕变试验中加载应力级的划分;等时曲线法将长期强度值视为考虑时效作用的屈服强度值,结果偏保守;应力松弛法考虑了循环加载条件应力松弛的终止条件和长期强度之间的关系求得,结果合理明确。该研究对考虑时效作用的工程岩体安全稳定性支护提供设计依据。

Comparative Study on Methods to Determine Long-term Strength of Discontinuity

The long-term strength of discontinuities contained in rock mass is directly relate to the stability of engineering rock mass,so a reasonable approach to determine it is of great significance for engineering design.In this paper,a series of stepwise shear loading creep tests and cyclic shear stress relaxation tests on artificial discontinuities were conducted to investigate the determination of long-term strengths.Three determination methods,i.e.transition creep method,isochronous curve method and stress relaxation method,were employed to determine long-term strengths,respectively.The longterm strengths determined by the above-mentioned methods are compare to each other.It is indicated that the transition creep method can only determine the long-term strength contained in a range whose accuracy depends on the loading steps.The isochronous curve method,which treats the long-term strength as the yield strength considering time-effect,is apt to be conservative.The stress relaxation method recommended in this paper can guarantee the reasonable and accuracy results of long-term strength,which provides reference for the design of engineering rock masses considering time effect.