用5种圆盘试件的劈裂试验确定岩石断裂韧度

Determination of rock fracture toughness by split test using five types of disc specimens

用5种不同形状的圆盘试件测定了大理岩张开型断裂韧度。5种圆盘试件分别为平台巴西圆盘、带有中心圆孔的平台巴西圆盘、人字型切槽巴西圆盘、直切槽巴西圆盘和圆孔切槽平台巴西圆盘。加载模式是对径压缩劈裂。介绍了试件的制作方法,提出了用每种圆盘确定断裂韧度的公式。结果表明,含有切槽圆盘的断裂韧度值在0.78～0.91MPa·m1/2之间,不含切槽圆盘测得的值在1.01～1.04MPa·m1/2之间。有3种含有切槽圆盘测得的断裂韧度值比较稳定,其中孔槽式平台巴西圆盘能够制作理想的宽度较小的切槽。

The opening mode fracture toughness of rock can be tested by five different configurations of disc specimens, which are flattened Brazilian disc, holed-flattened Brazilian disc, cracked chevron notched Brazilian disc, cracked straight-through Brazilian disc, and holed-cracked flattened Brazilian disc. The loading manner is splitting through diametrical compression. The machining method for specimens is introduced; and the formulas for determining the fracture toughness are given. The results of disc splitting test show that the values of fracture toughnesses for marble determined from the discs with notch are between 0.78 MPa·m^1/2 and 0.91 MPa·m^1/2; and the values determined from the discs without notch are between 1.01 MPa·m^1/2 and 1.04 MPa·m^1/2. It is found that values determining from the discs with notch are more stable; and more ideal thinner notch width can be achieved for the holed-cracked flattened Brazilian discs.