边坡潜在滑移面关键单元岩体裂隙演化特征细观试验与滑移机制研究

EXPERIMENTAL STUDY ON CHARACTERISTICS OF MICRO-CRACK EVOLUTION AT KEY PLACE OF POTENTIAL SLIP SURFACE OF SLOPES

利用自行研制开发的剪切蠕变细观试验装置与软弱煤岩细观力学特性测控软件,对边坡潜在滑移面关键区红砂岩进行系统剪切蠕变试验研究,分析红砂岩在不同载荷水平的剪切蠕变作用下细观裂纹扩展的时空演化规律及破坏后破裂面形态特征与剪切蠕变强度之间的关系,初步探讨边坡的滑移机制。结果表明:剪切蠕变作用下,红砂岩宏观蠕变变形与细观裂隙扩展同步进行;红砂岩裂纹扩展方向与剪切应力方向具有一定偏差,且出现多次分岔;裂纹多为绕晶体边缘扩展,扩展路径的不规则性受到岩体晶体分布特征的影响;岩体不同成分之间的应力响应差异、变形不协调和微裂隙之间的相互作用促进了裂隙的萌生和扩展,裂隙多在张拉和剪切共同作用下形成;破裂面粗糙度与剪切蠕变强度呈非线性递增关系,曲率呈先增大后减小趋势。

Shear creep tests on red sandstone were performed using the microscopic shear creep testing device and the monitoring software of coal micromechanics properties developed in-house. The temporal and spatial variation of the micro-cracks in red sandstone under the shear creep condition and the relationship between the morphological properties of the rupture surface and the shear creep strength were analyzed. The mechanism of the slope slip was also discussed. The creep deformation and the micro-cracks propagation were found to develop simultaneously. The direction of propagation of micro-cracks was not in the direction of shear stress and multiple bifurcations occurred in the process of crack propagation. Most cracks were along the boundaries of grains and the irregularity of the propagation path of cracks was affected by the distribution of rock grains. Micro-cracks were mostly produced by the tension and shearing together. The differences of stresses and the incompatible deformation at the different components of rock and the interaction of micro-cracks promoted the initiation and propagation of micro-cracks. The curve describing the roughness of rupture surface versus the shear creep strength increased non-linearly with the curvature increased at first then decreased.