反复直剪试验节理强度与粗糙度变化的研究

夏才初^{1, 2}，宋英龙^{1, 2}，唐志成^{1, 2}，宋英杰³

(1. 同济大学 岩土及地下工程教育部重点实验室，上海，200092；
2. 同济大学 地下建筑与工程系，上海，200092；
3. 中国恩菲工程技术有限公司 能源环境事业部，北京，100038)

摘 要：通过对人工模拟节理在不同法向应力作用下的4次反复直剪试验，分析节理峰值抗剪强度与反复剪切次数之间的关系以及节理粗糙度系数C_JR退化与剪切次数之间的关系，并提出考虑反复剪切次数n的节理峰值强度公式和节理粗糙度系数C_JR衰减的经验公式。研究结果表明：峰值强度随剪切次数的增加逐步减少，但第1次直剪试验得到的峰值抗剪强度与第2次直剪试验得到的峰值抗剪强度差异最明显，后3次直剪试验得到的峰值强度较接近；在相同的法向应力作用下，C_JR随剪切次数的增加而减少，但减少速率逐步变小。

关键词：岩石力学；节理；直剪试验；剪切次数；峰值抗剪强度

Shear strength and morphology characteristic evolution of joint surface under cyclic loads

XIA Cai-chu^{1, 2}, SONG Ying-long^{1, 2}, TANG Zhi-cheng^{1, 2}, SONG Ying-jie³

(1. Key Laboratory of Geotechnical and Underground Engineering, Ministry of Education,
Tongji University, Shanghai 200092, China;
2. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China;
3. Department of Energy and Environment Engineering, China Enfi Engineering Corporation, Beijing 100038, China)

Abstract:Based on the shear tests of artificial rock joints under different normal stresses for four times, the relationship among the peak shear strength, shear test times and normal stress and between the roughness coefficient and shear test times were analyzed. A new shear strength criterion and roughness coefficient C_JR degradation criterion were proposed considering the effects of both the normal stress and test times. The results show that the peak shear stress decreases gradually with the increase of the test times, and the difference is apparent between the first and the second time. The peak shear strengths of the last three times are close to each other. Under the same normal strength, C_JR decreases with the increase of the test times, but the decrease rate is slower and slower.

Key words:rock mechanics; rock joint; direct shear test; shear times; peak shear strength