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| Experimental study on acoustic and mechanical properties of intermittent jointed rock mass |
| ZHAO Xiucheng1，ZHAO Xiaoyan1，GUO Jiaqi2 |
(1. Faculty of Geosciences and Environmental Engineering，Southwest Jiaotong University，Chengdu，Sichuan 611756，China；2. School of Civil Engineering，Henan Polytechnic University，Jiaozuo，Henan 454003，China)
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Abstract The influence of intermittent joints on the strength of rock masses and its evaluation method have always been one of the hotspots and difficulties in the field of rock mass mechanics. In this paper，45 samples of intermittent jointed rock mass are made from gypsum with different combinations of joint inclination，density connectivity，and ultrasonic wave speed and uniaxial compression strength(UCS) tests are performed. The correlation characteristics between the mechanical and acoustic parameters are investigated，the influence of the distribution characteristics of joints on the rock mass failure mode and UCS is explored and consequently a determination method of the UCS of intermittent jointed rock mass is proposed. The results show that the P-wave velocity is positively correlated with the joint connectivity and has an approximately V-shaped change with increasing the joint dip angle，and that both the UCS and the elastic modulus(E) of the jointed rock mass increase with increasing the joint connectivity and the UCS presents an approximately U-shaped change with increasing the joint dip angle. Four fracturing modes of intermittent jointed rock masses are proposed and it is pointed out that samples are most prone to fail when the joint forms a 45°angle with the loading direction. Finally，a fitting relationship between the UCS of jointed rock masses and intact rock block is proposed by considering not only the P-wave velocity but also the internal friction angle of the rock block and the joint dip angle.
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2020, Vol. 39 
