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渗透率是地下工程的流-固耦合分析中的一个关键因素。对多孔红砂岩进行了三轴压缩试验,在不同变形阶段实施了轴向应力循环加卸载,并在试验全过程中测量轴向渗透率,得到了试样破坏全过程的渗透率演化规律。从平均应力和循环加卸载对渗透率的影响等两方面进行了深入分析,结果表明,(1)随着轴向变形的增加,初始压密阶段和弹性变形试样渗透率均匀减小;进入塑性变形阶段,渗透率与轴向变形的曲线逐渐趋于水平,低围压条件下渗透率略有增加。(2)轴向加载使骨架颗粒被压缩,引起孔隙减小,造成渗透率减小;采用经验公式定量描述了渗透率和平均应力之间的关系。(3)轴向应力循环加卸载过程中,骨架颗粒的不可恢复变形引起渗透率产生不可恢复现象。(4)峰值后渗透率只发生少许突跳,说明对于多孔砂岩,孔隙和裂隙对渗透率的影响相当,且渗透率的突跳程度随着围压的升高而降低。
Permeability is a key factor in the fluid-solid coupling analysis of underground engineering. The porous red sandstone was subjected to triaxial compression tests. Axial stress cycles were loaded and unloaded during different deformation stages. Axial permeability was measured during the whole experiment. The permeability evolution of the whole sample was obtained. The results show that: (1) As the axial deformation increases, the permeability of the initial compaction stage and elastic deformation specimen decrease uniformly; During the plastic deformation stage, the curves of permeability and axial deformation gradually become horizontal, and the permeability increases slightly under low confining pressure. (2) The axial loading causes the skeleton particles to be compressed, causing the pores to decrease, resulting in the decrease of permeability. The empirical formula is used to quantitatively describe the relationship between permeability and average stress. (3) In the process of axial stress cycle loading and unloading, the irreversible deformation of the skeleton particles causes the irreversibility of the permeability. (4) After the peak, there is only a few kicks in the permeability, which shows that for the porous sandstone, the influence of porosity and fracture on the permeability is similar, and the kurtosis of permeability decreases with the increase of confining pressure.