层状岩体力学特性模拟实验研究

On the Simulative Experimental Study of Mechanical Properties of Stratified Rock Mass

对层状岩体变形特性和强度特性的正确认识,合理选取其变形和强度参数,是水电站等大型岩体工程论证与设计需要解决的关键问题。为此,利用模拟实验对层状岩体的变形特性和强度特性进行了研究,得到了模拟试样的变形模量和强度随试样所含节理数、轴向应力与节理面间的夹角和围压之间的变化关系。结果表明:当最大主应力与节理面间的夹角由0°增加至90°时,试样的应力-应变全过程曲线形状存在显著差异。其变形模量整体上遵循由大变小,再由小变大的变化趋势,强度遵循三角函数变化规律。当夹角为0°、75°和90°时,试样的破裂特性基本不受节理面的影响。其它夹角或含多条节理的试样其破裂面受节理面的影响较大,破裂面大部分沿节理面发育,形成与节理面同倾向的宏观破裂面。当破裂面穿过节理间的基质层时会形成剪张性破裂带,该带的宽度受夹角大小和试样所含节理数的影响。

It is a key problem to be solved for large-scale rock engineering demonstration and design such as hydropower to understand the deformation and strength characteristics of stratified rock-mass, and to select its deformation and strength parameters. So, the deformation and strength characteristics of stratified rock-mass were studied based on simulative experimental data, and relations among the deformation modulus and the strength of simulative sample and joint number contained in the sample, inclination angl＇e between axial stress and joint plane and confining pressure were obtained. Results show that when the inclination angle between the maximum principal stress and the joint plane al increases from 0° to 90°, obvious difference in sample＇ s stress-strain curve exists; its deformation modulus follows the tendency as a whole from bigger to smaller at first, then from smaller to bigger later; its strength changes as circular function. When the inclination angle equals to 0°, 75° and 90° respectively, the sample＇s break property is basically not affected by joint plane. When the inclination angle does not equal to 0°, 75°and 90°respectively, or the sample contains more than 1 joint, the break characteristics are affected seriously by the joint plane. Most parts of break plane grow along the joint and form break plane in same inclination direction. When break plane crosses through the layer between joint planes, a shear-expanding break belt forms, and its width is affected by the angle al and joint number contained in the sample.