弹性拉拔中锚杆轴力和剪力分布力学计算

Elastic stress distributions:axial and shear stress distributions in an anchor bolt during a pullout test

通过构建平面和三维力学模型,推导了弹性状态下沿杆长方向轴力和黏结剪应力的分布函数,提出了锚杆剪应力衰减系数的概念,并给出了力学算式;对比分析了围岩为砂岩和煤体时,水泥锚固和树脂锚固两种情况下,锚杆轴力和剪力的衰减特征.结果表明:软岩锚固中轴力和剪力为全长分布型,硬岩0.8～1.0m左右即衰减为拉拔力的5%,黏结剪应力的主要作用范围为0～0.5m,在0.4～0.5m处衰减为0.06MPa左右.

Planar and 3-D mechanical models were used to test rock-bolt pull out. The results were used to derive formulas for the axial force and bond shear stress in the bolt under elastic conditions. A new term, the decay of shear stress coefficient, is proposed that has an obvious effect on the stress distributions. Theoretical estimates of how cement or resin-anchored bolt stresses decay in sandstone rock are presented. These estimates are then compared to bolt properties in a coal body. Axial force and grout shear stress in soft rock are found to be distrib- uted along the entire length of the bolt. However, in hard rock the axial force decays rapidly, dropping by 95 percent along 80 to 100 cm in the grout. The grout shear stress decays to 0.06 MPa within about 40 to 50 cm in the grout.