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| An empirical formula for peak shear strength of irregular sandstone joints under seepage flow |
| CHENG Tan1，GUO Baohua1，2，3，SUN Jiehao1，TIAN Shixuan1，CHEN Yan1 |
| (1. School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454000，China；2. The Collaborative Innovation Center of Coal Safety Production of Henan Province，Henan Polytechnic University，Jiaozuo，Henan 454000，China；3. Jiaozuo Engineering Research Center of Road Traffic and Transportation，
Henan Polytechnic University，Jiaozuo，Henan 454000，China) |
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Abstract To study the effect of seepage on shear mechanical properties of rock joints，direct shear tests on 10 irregular sandstone joints in non-seepage natural state and 25 irregular sandstone joints in seepage state were carried out using the rock joint shear-seepage test device which is modified by RDS–200 rock direct shear apparatus. The influences of seepage pressure，normal stress and joint roughness on the shear mechanical properties of rock joints are analyzed，and the empirical formula for the peak shear strength of irregular sandstone joints under seepage is proposed. The results show that compared with the natural state without seepage，the peak shear strength of rock joints decreases，the peak shear displacement increases，and the pre-peak shear stiffness decreases in seepage state. Based on the empirical formula of peak shear strength of rock joints proposed by Barton，considering the effective stress principle and the influence of seepage water pressure on the basic friction angle together，the empirical formula of peak shear strength of irregular sandstone joints under seepage condition is proposed. Only two test parameters which can be easily to obtain(rock joint wall strength JCS and seepage water pressure) are added in the formula，and it has a good fitting effect on the test data of rock joint shear strength under seepage condition，which is helpful to accurately estimate the peak shear strength of rock joint under seepage condition.
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2022, Vol. 41 
