顺层陡倾岩质边坡变形机理探究

Research on Deformation Mechanism of Steep Bedding Rock Slope

顺层岩质边坡是指坡向与岩层倾向一致的边坡,自然界中广泛分布。在顺层陡倾岩质边坡中往往存在滑移-弯曲变形和倾倒变形两种变形破坏模式,它们的典型变形特征与变形演化过程截然不同。总结了顺层陡倾岩质边坡滑移-弯曲变形和倾倒变形的典型特征,开展了不同边坡坡角、岩层倾角组合下边坡的底摩擦模型试验,揭示了顺层陡倾岩质边坡的变形机理和影响因素。结果表明:(1)工程实例统计分析显示,倾倒变形往往发生于岩层倾角为70°~90°、边坡坡角为40°~60°、且边坡坡高大于300 m的顺层陡倾岩质边坡中,而滑移-弯曲变形往往发生于岩层倾角为50°~70°、边坡坡角为15°~60°、且边坡坡高在300 m左右的顺层陡倾岩质边坡中;(2)顺层陡倾岩质边坡倾倒变形的典型变形特征表现为中上部岩体呈现滑移-倾倒变形,中下部岩体呈现弯曲-倾倒变形,整个变形演化过程可以概括为卸荷回弹、滑移-倾倒和蠕变-滑移3个阶段;(3)数值模拟结果显示,岩层陡倾角是顺层陡倾岩质边坡发生滑移-弯曲-倾倒变形的必要条件,当边坡坡角大于60°且岩层倾角与边坡坡角之差小于15°时,顺层陡倾岩质边坡往往发生滑移-弯曲变形,而当边坡坡角大于60°且岩层倾角与边坡坡角之差大于15°时,则其发生滑移-弯曲-倾倒变形。

The bedding rock slope is a kind of slope widely distributed in nature.There are two deformation and failure modes of"sliding-bending"and"toppling deformation"in the steep bedding rock slope,and their typical characteristics and deformation process are quite different.This paper summarizes the typical characteristics of the steep bedding rock slope,carries out bottom friction model test research and numerical simulation with different slope angles and dip angles combinations,and then studies the deformation process of the steep bedding rock slope,and reveals the deformation mechanism and influencing factors.Indications of the results are as follows:(1)The statistical analysis of engineering examples shows that toppling deformation often occurs in bedding rock slopes with dip angles of 70°-90°,slope angles of 40°-60°,and slope heights greater than 300 m while"sliding-bending"often occurs in bedding rock slopes with dip angles of 50°-70°,slope angles of 15°-60°,and slope heights about 300 m.(2)The typical characteristics of toppling deformation of the steep bedding rock slope are that the upper rock mass of the slope shows the failure of"sliding-toppling"while the rock mass in the middle and lower part of the slope shows the failure of"bending-toppling".The"sliding-bending-toppling"process is dominated by shear failure,and the whole deformation process can be summarized into three stages:unloading rebound stage,sliding-toppling stage,and creep and slip stage.(3)Numerical simulation results show that the steep dip angle is the necessary condition for the steep rock bedding slope to form"sliding-bending-toppling"deformation.When the slope angle is greater than 60°and the difference between the dip angle and the slope angle is less than 15°,the bedding slope tends to have"sliding bending"deformation,while the slope angle is greater than 60°and the slope angle is greater than 15°,the"sliding bending toppling"deformation occurs.