复杂节理岩体的剪切强度特性的尺寸影响研究

基于三维块体离散元软件3ＤＥＣ程序，考虑存在三组节理的复杂节理岩体的情况，通过对10个不同尺寸的岩体块体进行直剪试验模拟，探讨岩体尺寸对于剪切强度特性的影响效果。由于剪切面相对节理面位置的不同，块体分为两组（第Ⅰ、Ⅱ组），得出了法向应力作用下的剪切应力与水平位移的关系曲线图。通过计算可得出剪切强度参数———黏聚力和摩擦角及其与块体尺寸的关系曲线。由此可见，两组的差异较大，故在进行选择参数时应根据剪切面的位置分别进行考虑。最后对岩体的剪切强度特性的尺寸效应进行了理论分析，认为节理岩体的剪切强度特性的尺寸影响的关键原因是节理结构面的存在，节理的相对位置、组数、间距、材料属性等都是重要的影响因素。

Size Effect to Shear Strength of Jointed Rock Masses

Shear strength characteristics of rock is one of the indicators of rock mechanical properties,thus the study of size effect has been a subject of particular concern of scholars,so the impact study of the size to jointed rock mass shear strength characteristics emerged.Based on three-dimensional block discrete element software program 3DEC,considering the case of the presence of three sets joints of jointed rock mass,through direct shear test simulation of rock blocks of different sizes,explore the effect of dimension to shear strength characteristics.Due to the different positions of the shear plane,blocks are divided into two groups (Group Ⅰ 、Ⅱ),a graph of shear stress and horizontal displacement under the action of normal stress was acquired.It can be derived by calculating the shear strength parameters-cohesion and friction angle,and the curves with the rock size.It shows large differences between the two groups,therefore,it should be considered separately when selecting these parameters,and theoretically analyze rock size effect to shear strength propriety.The key reasons for shear strength of jointed rock mass affected by size is the presence of joint structural planes,besides the relative position of joints,the number of joint groups,spacing,material properties etc.are all important influence factors.