饱水-风干作用下砂岩断裂韧度与抗拉强度研究

Research on fracture toughness and tensile strength of sandstone under water-saturated and air-dried circulation

为了解考虑时间效应的饱水-风干循环作用时砂岩Ⅰ型断裂韧度、抗拉强度的变化规律及其相关性,选取三峡库区库水位变幅带砂岩为研究对象,对周期性饱水-风干循环状态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:在饱水风干循环作用下,砂岩的断裂韧度和抗拉强度软化效应明显,且试验前期砂岩强度软化效应较大,后期趋于稳定。同时,在同一时间周期内,砂岩试样的断裂韧度和抗拉强度具有相近的软化系数。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,并通过与相关其他试验成果的比较,验证了公式的可靠性。

In order to investigate the variation and correlation of fracture toughness and tensile strength of sandstone under saturation-air dry circulation with consideration of time effect,we conducted three-point bending fracture toughness test and splitting tensile strength test for sandstone samples that were selected in water-level fluctuating zone of Three Gorges Reservoir area.The test results show that under water-saturated and air-dried circulation,the fracture toughness and tensile strength of sandstone both have obvious softening effect that is larger in early test period and tend to be stable in the later period.Meanwhile,the fracture toughness and tensile strength of the sandstone have similar softening coefficient in the same time period.Through data fitting,we obtain the correlation between fracture toughness and tensile strength with a high relativity.Compared with other related experimental results,the reliability of formula is verified.