摘要
为研究岩石压拉应力下的强度和破坏,对外径50mm、孔道6～25mm的孔道圆柱试样进行不同轴压下的内压致裂试验,对外径50mm、孔道4.6～20.0mm的圆环进行巴西劈裂试验。试验结果表明:轴向应力低于单轴压缩强度80%时孔道试样在内压下拉伸破裂,压力与轴向应力没有明显关系;试样承载的孔道内压随孔道直径的增加而减小,孔壁的最大拉应力也随孔道直径的增加而略有减小,试样承载的平均切向应力随孔道直径明显增加;孔道试样能够承受的拉应力远大于巴西劈裂强度,如内孔直径25mm的试样可以承载10MPa的内压,切向拉应力在内壁为17MPa左右、外侧面为7MPa左右,而6个完整圆盘的巴西劈裂强度最大值仅为6.17MPa。内孔直径小于20mm的试样,因内压增大孔壁处岩石拉伸变形增大到极限、引起裂纹扩展,最终破裂成2块;而内孔直径25mm的试样,在内孔压力达到破裂压力时,孔壁处材料没有达到断裂所需要的变形,因而只有试样外侧也达到屈服应力才能整体断裂。承载非均匀应力的岩石结构需要考虑载荷和变形2个破坏指标。
To study the strength and failure of rock under compression-tension stresses,hollow cylinders with 50 mm in outer diameter and 6-25 mm in inner diameters were cracked by inner hydraulic pressure under different axial loads;and ring specimens with 4.6-20.0 mm in inner diameters were tested with Brazilian split.The experimental results show that the cracking pressure for hollow cylinder is not influenced by the axial load when it is lower than 80%of the uniaxial compression strength.The cracked pressure decreases with the increase of the inner diameter;and the tangential stress at the hole wall also decreases slightly,but the average of tangential stress increases.The hollow cylinders can hold tensile stress much higher than that of the Brazilian disc.The cracking pressure for hollow cylinder with inner diameter of 25 mm is about 10 MPa;and the tangential stress is about 17 MPa on the inner surface and 7 MPa on the out surface.However,the maximum strength in 6 pieces of Brazilian disc is only 6.17 MPa.Hollow cylinders with inner diameters less than 20 mm failed for the deformation on the inner surface increasing to the limitation and cracked into two parts.Hollow cylinders with inner diameters of 25 mm failed for the tangential stress on the out surface increasing to the tensile strength,and single crack was produced.Two indices of deformation and stress are related to the failure of rock specimen suffered from nonuniform stresses.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2010年第6期1096-1105,共10页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(10572047)
关键词
岩石力学
孔道试样
圆环试样
破坏形式
内压致裂
巴西劈裂
rock mechanics
hollow cylinder
ring specimen
failure modes
inner pressure crack
Brazilian split
