级配饱和破碎岩石压缩变形与分形特性试验研究

Experimental study on compaction and fractal characteristics of saturated broken rocks with different initial gradations

综合利用MTS816.03试验系统与自制的破碎岩石压缩装置进行了不同岩性饱和破碎岩石的压缩试验,分析了岩性、轴向应力、粒径配比和加载速率4种影响因素下试样的压缩变形与分形特性。得出以下结论：1）矸石、泥岩和砂岩试样的压缩过程相似且可分为2个阶段,即为0~4MPa的快速变形阶段和4 MPa后的缓慢变形阶段;而灰岩试样的压缩过程变形速率均匀。2）在相同粒径配比条件下,随着轴向应力的增大,砂岩分形维数单调增大,岩石颗粒破碎程度加剧。轴向应力与分形维数之间关系可用指数函数拟合。3）在试样压缩过程中,Talbol幂指数越大,试样轴向位移越大;加载速率越大,试样轴向位移越小。4）在12 MPa轴向应力下,Talbol幂指数越大,试样压缩后的分形维数增量越大,被压碎的岩石颗粒越多;加载速率越大,试样分形维数越大,破碎程度越低。

Using the MTS816.03 test system and self-designed compression apparatus for broken rocks, the compaction tests for saturated broken rocks with different lithologic have been conducted, and the influence of lithology, axial stress, initial gradations and loading rate on compaction deformation and fractal characteristics has been analyzed. The results have shown that：1） The compaction processes of gangue, mudstone and sandstone are similar and can be divided into two stages, including the rapid compaction deformation stage（0-4 MPa） and the slow compaction deformation stage（after 4 MPa）. However, the compaction deformation rate of limestone is steady. 2） Under the same initial gradation, as axial stress increases, the fractal dimension of sandstone samples increases monotonously, and the breaking degree gets higher. The relations between fractal dimension and axial stress can be described by exponential function. 3） In the compacting process, as the Talbol exponent increases, the axial displacement increases. As the loading rate increases, the axial displacement decreases. 4） Under the same axial stress, 12 MPa, as the Talbol exponent increases, the increment of fractal dimension increases and the quantity of rock particles crushed increases. As the loading rate increases, the fractal dimension decreases, and the breaking degree gets lower.