不同饱水强度灰岩应变及微观孔隙分布特征研究

为揭示饱水强度对灰岩应变和微观孔隙分布特征的影响,对四组灰岩进行了强制饱水试验、单轴压缩试验、压汞试验,测得了应力—应变和压汞曲线。结果表明,与低饱水试样相比,高饱水灰岩的压密阶段相对延长而弹性阶段相对缩短;饱水强度显著降低了灰岩脆性而未对破坏类型造成较大影响,以剪切破坏为主;随饱水强度增加,平均峰值强度和平均弹性模量分别呈指数和对数衰减,闭合应力呈指数增加;进汞量—孔径曲线呈三次函数变化,小孔隙区域、中孔隙区域和大孔隙区域的孔径分界点为2 000、30 000nm,中型孔径孔隙决定孔隙度和损伤程度;单位质量进汞体积累计量随饱水强度呈一阶指数增加。

Study on Strain and Microscopic Pore Distribution Characteristics of Limestone under Different Saturation Intensities

To reveal the influence of different saturation intensity on the mechanical properties and microscopic pore distribution characteristics of limestone, four groups of limestone samples were subjected to forced saturation test, uniaxial compression test and mercury injection test. And then the stress-strain curve and mercury injection curve were measured. The results show that the compaction stage of higher saturation intensity is longer and its elastic stage is shorter than that of lower saturation limestone. Water saturation significantly reduces the brittleness but has no significant impact on its failure type. With increasing saturation intensity, the average peak strength and average elastic modulus decreases with exponential function and logarithmic function respectively, while the closed stress increases with exponential function. The curve of mercury intake-pore size changes in a cubic function, and its corresponding pore size boundaries of the small pore area, middle pore area and large pore area are 2 000 nm and 30 000 nm. The pores that in the middle pore area determine the porosity and damage degree of limestone. The accumulative mercury volume per unit mass increases a first-order exponentially with the saturation intensity.