水岩作用下砂岩断裂韧度及抗拉强度的试验研究

为了解在考虑时间效应的水岩作用下砂岩Ⅰ型断裂韧度、抗拉强度的变化规律及其相关性,选取三峡库区库水变幅带砂岩为研究对象,设计紧凑的实验方案,对周期性饱水-风干循环状态和长期饱水状态下的砂岩试样开展了三点弯曲断裂韧度试验和劈裂抗拉强度试验.试验结果表明:在水岩作用下,砂岩的断裂韧度和抗拉强度软化效应明显,且随着浸泡时间的增加,软化效应呈先增大后稳定的趋势.同时,在同一周期内砂岩试样的断裂韧度和抗拉强度有相近的软化系数,契合岩石的抗拉强度和断裂韧度存在较好的相关性.最后通过数据拟合得到了砂岩断裂韧度与抗拉强度的相关关系,拟合相关性较高,并通过与试验数据的比较,验证了公式的可行性.研究成果对水岩作用下砂岩断裂韧度与抗拉强度的相关性有一定的参考价值,为通过砂岩抗拉强度预测估算断裂韧度提供了便利,同时也可为其他类型岩石的相关研究提供参考.

Experimental Research on Fracture Toughness and Tensile Strength of Sandstone under Water-Rock Interaction

In order to understand the variation and correlation of fracture toughness and tensile strength considering time effect under water-rock interaction, we conducted three point bending fracture toughness test and splitting tensile strength test according to the design of the experiment scheme for compact on sandstone samples in periodic full water-air dry cycle state and long-term saturated state which were selected from Three Gorges reservoir area reservoir water with horn. Test results show that under water-rock interaction, the fracture toughness and tensile strength of sandstone softening effect is obvious; and softening effect is first increases, then stable trend along with the increase of soak time. Meanwhile, the fracture toughness and tensile strength of the sandstone in the same time period have similar softening coefficient, corresponding rock tensile strength and fracture toughness good correlation exists. Finally, through the data fit got sandstone fracture toughness and tensile strength of the correlation fitting high correlation, and through comparison with experimental data, we can verify the feasibility of formula. The research results have some reference value for the correlation of fracture toughness and tensile strength of sandstone under water-rock interaction; and provide a convenient way for through the sandstone tensile strength prediction estimating fracture toughness and the reference for the other types of rock related research.