考虑自由段受荷的锚杆变形和承载特性研究

针对锚杆端部的拉拔荷载由锚固段的锚固体和自由段的锚固体共同承受的特点,采用反映土锚界面抗剪强度衰减的双折线模型,基于荷载传递理论推导得到锚杆抗拔力与位移之间的解析关系式,工程实例计算结果验证了理论推导的正确性.计算结果表明:自由段受荷后对锚杆的刚度和承载力都有明显的提高,且随着自由段长度的增加,其承载力会有所提高,但锚杆整体刚度却在降低,因此在预应力锚杆的设计与施工中应合理地选择自由段长度.

Research on the Deformation and Bearing Characteristics of Anchor Considering the Load Bearing of Free Section

Considering the common load bearing features of free section and anchoring section of the prestressed anchor bolt and using the double broken line model,which can present the damping properties of the soil-bolt surface strength,the analytical solutions between bolt resistance force and displacement was obtained based on the load transfer theory.Engineering example analysis verified the correctness of the theoretical derivation.The calculation results indicate that the stiffness and strength of the prestressed bolt are improved when the bearing capacity of free section is taken into account.The calculation results also show that the bearing capacity of the whole bolt increases,but the stiffness decreases on the contrary,while the free section length increases.So it is important to determine the rational length of free section in prestressed anchor bolts design and construction.