饱和级配破碎泥岩压实与粒度分布分形特征试验研究

通过饱和级配破碎泥岩的压实试验，得到了不同级配下试样轴向位移和粒度分布分形维数随轴向应力变化曲线，分析了Talbol幂指数对饱和破碎泥岩压实变形与粒度分布的影响规律，建立了一种饱和破碎泥岩压缩模量与轴向应力的关系式。试验结果表明，饱和破碎泥岩的压实过程可分为2个阶段，即0~4 MPa的快速变形阶段和4 MPa后的缓慢变形阶段。其中，约80%的变形发生在快速变形阶段。轴向位移、压缩模量与粒度分布分形维数均可用轴向应力的指数函数拟合。相同轴向应力下，Talbol幂指数越大，试样轴向位移越大，粒度分布分形维数越小。轴向应力大于8 MPa后，各级配试样的粒度分布分形维数相差很小，且随着轴向应力的进一步增大，各级配试样的分形维数差异将继续减小，最终，分形维数将趋于一致。在加载初期，试样压实变形主要以岩石颗粒移位为主；而在加载后期，试样的压实变形则以颗粒破碎为主。

Experimental study of compaction and fractal properties of grain size distribution of saturated crushed mudstone with different gradations

By the compacting test on saturated crushed mudstone with different gradations, the curves of axial displacement and grain size distribution with variable axial stress are obtained; and the influence of Talbol exponent on the compaction deformation and grain size distribution is analyzed. In the end, the relationship between compression modulus and axial stress is established. The experimental results indicate that the compacting process of saturated crushed mudstone can be divided into two stages: the rapid deformation stage (0-4 MPa) and the slow deformation stage (after 4 MPa). And about 80% of the deformation occurs in the first stage. Axial displacement, compression modulus and fractal dimension can be fitted by the exponential functions of axial stress respectively. Under same axial stress, the axial displacement increases and the fractal dimension decreases with the Talbol power exponent increasing. After the axial stress exceeds 8 MPa, the fractal dimensions of samples with different grain size distributions are very close. In addition, with the further increase of the axial stress, the fractal dimension difference between samples with different gradations will continue to decrease; and finally, the fractal dimension will tend to be consistent. In the initial stage of loading, the compaction deformation of samples mainly results from movement of rock particles, and in the late loading, the compaction deformation mainly results from rock particles crushing.