硬石膏岩浸水后单轴抗压强度变化规律试验研究

Experimental Study on Uniaxial Compressive Strength of Water Immersed Anhydrite

硬石膏质岩浸水后生成二水石膏,岩石内部孔隙被结晶水填充导致强度发生变化。为研究硬石膏质岩浸水后抗压强度与硬石膏含量、硬石膏水化率的关系,在实验室内对106块不同含量的硬石膏岩试件进行了浸水后的室内单轴抗压强度试验,试验结果揭示:在不同水化率条件下,岩石试件的单轴抗压强度与试件硬石膏含量的关系不能用统一的函数形式进行描述,其中,岩石的水化率0.65~0.7,0.8~0.84的前后其单轴抗压强度函数曲线发生较大变化;不同硬石膏含量时,岩石单轴抗压强度与硬石膏水化率的函数曲线呈下凹曲与上凹两种形态,这两种形态曲线的变化拐点出现在石膏含量0.64~0.78间;岩石单轴抗压强度与硬石膏含量、硬石膏水化率三者在空间上呈现“飞鱼”状的不规则曲面关系,其中在水化率为0、水化率大于0.8和石膏含量大于0.7、水化率为0.5~0.7和硬石膏含量0.6~0.65这3处位置的岩石单轴抗压强度属于高势区;岩石水化率为0.35~0.45和水化率0.2~0.6,石膏含量0.7~1及水化率大于0.75,石膏含量小于0.6,这3处位置的单轴抗压强度为低势区。硬石膏岩水化反应是一项十分复杂过程,水化后的岩石强度受控于水化程度和石膏含量两因素。

Anhydrite becomes dihydrate gypsum after immersion in water, its inner pore is filled with crystalline water which makes its strength change. In order to study the relationship of the compressive strength of water immersed anhydrite with content and hydration rate of anhydrite, the uniaxial compressive strength test on 106 blocks of water immersed anhydrite with different anhydrite contents is carried out in the laboratory. The test result shows that (1) Under different hydration rates, the relationship between uniaxial compressive strength and anhydrite content of the rock sample cannot be described as an unified functional form, the function curves of uniaxial compression strength of the rock whose hydration rates around 0.65-0.7 and 0.8-0.84 have great changes.(2) Under different anhydrite contents, the function curves of uniaxial compression strength and hydrating rate of anhydrite can be divided into concave curve type and concave curve type, and the turning point is between the gypsum content of 0.64-0.78.(3) It appears as an irregular surface of "flying fish" among the uniaxial compression strength, the content of anhydrite and the hydrating rate of anhydrite in space. When the hydration rate is 0, the hydration rate is more than 0.8 and the gypsum content is greater than 0.7, the hydration rate is 0.5-0.7 and the anhydrite content is 0.6-0.65, the uniaxial compression strength belongs to the high potential area. When the hydration rate is 0.35-0.45 and the hydration rate is 0.2-0.6, or the gypsum content is 0.7-1 and the hydration rate is greater than 0.75, or the gypsum content is less than 0.6, the uniaxial compression strength belongs to low potential area. The hydration reaction of anhydrite is a very complex process, and the strength of the water immersed hydrated rock is controlled by hydration degree and gypsum content.