不同长度石灰岩动态压缩力学性质试验研究

Study on dynamic compression mechanical properties of limestone with different lengths

为研究高应变率下岩石力学性质尺寸效应,采用Ф50mm分离式霍普金森压杆装置(SHPB)对直径50mm,长度为15~100mm的12种规格的石灰岩试件进行冲击加载试验。结果表明,石灰岩试件单轴动态抗压强度存在明显的尺寸效应,动态抗压强度随试件长度变化呈先增大后减小的趋势,在试件长度为60mm时强度最大;长度为15~35mm的试件应力-应变曲线的形态变化比较大,试件长度大于35mm时随着试件长度的增大应力-应变曲线大致形态变化不大;随着试件长度的增大,试件的峰值应变呈减小趋势,试件的动态弹性模量呈先增大后减小的变化趋势在试件长度为60mm时存在一个峰值;随着试件长度的增大破碎程度呈先减小后增大的变化趋势与强度存在相关性,强度越大试件破坏越弱。

In order to study the size effect of rock mechanics under high strain rate,Ф 50 mm split Hopkinson pressure bars(SHPB) was used to carry out impact loading test for 12 types of limestone specimens with diameter of 50 mm and length of 15 mm to 100 mm. The results show that the single axis dynamic compressive strength of limestone specimens has obvious size effect,and the dynamic compressive strength increases first and then decreases with the change of the length of the specimen. The strength of the specimen is the maximum at the length of 60 mm,and the stress strain curve of the specimen with a length of 15 mm to 35 mm is larger and the length of the specimen is more than 35 mm. With the increase of the length of the specimen,the stress strain curve generally has little change. With the increase of the length of the specimen,the peak strain of the specimen decreases,and the dynamic elastic modulus of the specimen increases first and then decreases when the length of the specimen is 60 mm,and the fracture degree is first with the increase of the length of the specimen. There is a correlation between the decreasing trend and the increase trend. The greater the strength is,the weaker the failure is.