单轴压缩条件下岩体内部蠕变特性试验研究

    Creep Characteristics of Rock Mass Interior Under Uniaxial Compression

    • 摘要: 基于岩体相似匹配特性,采用铁晶砂胶结岩土相似材料制作正方体似砂岩试块,试验前把改进的三维直角式接触应变花预埋进试块内部,接着在岩石蠕变仪上进行岩体相似模拟试块的蠕变试验。通过分析试块内部应变的测量结果,得出岩体内部某点蠕变变形的三维应变状态矩阵,通过假定试块中心点O为空间直角坐标系原点(0,0,0),α角为射线OA在xOy平面上投影与x轴的夹角,β角为射线OA在yOz平面上投影与z轴的夹角,用点O(0,0,0)、α角、β角便可以确定射线OA的三维空间位置。接着利用三维应变矩阵反算任意时刻OA方向应变值达到最大时所对应的α、β角度就可以表征岩体内部的蠕变特征。计算结果表明:α、β角度值和最大应变值在低荷载阶段均呈稳定发展;在高荷载阶段,当隐性裂纹产生时,α、β角度值和最大应变值在同一时刻发生突变且角度值和应变值的突变方向相反。

       

      Abstract: The paper is based on the similarity matching characteristics of rock mass, and took cube block as specimen with similar materials. During the process of making specimen, the improved three dimensional right angle contact strain rosette was embedded into interior of the test block. Then, the test block is placed on the YR-2000 rock creep tester for uniaxial compression test. Based on the measurement data of the internal strain of the test block, a three-dimensional strain state matrix of a certain point of creep deformation in the rock mass can be obtained. It is assumed that the center point O of the test block is the origin of the space right angle coordinate system (0,0,0), and alpha(α) is the angle of the ray OA between the xOy plane and the x axis, beta(β) is the angle of the ray OA between the yOz plane and the z axis. The three-dimensional space position of the ray OA is determined by the point O (0, 0, 0), alpha (α) angle, and beta(β) angle. And the data of alpha (α)and beta(β) angle corresponding to the maximum strain value of OA direction can be representation of creep characteristics of rock mass. The results showed that the α, β angle values and the maximum strain value are stable at low load stage. In the high load stage, when the recessive crack occurs, the α, β angle values and the maximum strain value are abruptly changed at the same time. Moreover, the α, β angle values and the strain values are reversed in the opposite direction.

       

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