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| Experimental study of mechanical properties of staggered zones under loading and unloading conditions of high stresses#br# |
| DUAN Shuqian1，FENG Xiating1，JIANG Quan1，XU Dingping1，XU Hong2，LIU Guofeng1 |
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy
of Sciences，Wuhan，Hubei 430071，China；2. Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines，
Northeastern University，Shenyang，Liaoning 110819，China) |
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Abstract For staggered zones revealed in Baihetan underground powerhouse with complex mechanical response behavior，a series of undrained triaxial conventional and unloading tests under different stress levels and paths were carried out to study the mechanical properties of staggered zones under loading and unloading in high stress conditions. In the unloading process，the unloading stress-strain curves were related to the initial confining pressure，deformation rebounded in the direction of unloading and strong dilation occurred from the start of unloading. The lateral expansion in the course of the unloading of the axial and confining pressure was more significant than that in the course of loading axially and unloading of confining pressure. The tensile-shear cracks appeared in the surface of the staggered zone samples. For the stress unloading path，the deformation modulus was degraded with the decrease of confining pressure，which was described with a cubic polynomial. The bulk modulus was decreased exponentially with the increasing of volumetric strain. The Poisson?s ratios of interlayer zone samples increased gradually with a parabola trend. In comparison to the loading conditions，the failure stress was decreased and the internal friction angle was increased and the cohesion was reduced significantly. The degradation in the course of unloading of axial and confining pressure was more significant than that in course of loading axially and unloading of confining pressure.
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2016, Vol. 35 
