为研究预应力锚杆内锚固段长度对杆体轴力及围岩支护效果的影响，将锚杆内锚固段长度与杆体总长度之比定义为内锚固段长度系数，根据锚固界面剪应力计算公式，推导锚杆轴力与杆体伸长量的关系式。在分析内锚固段长度系数对杆体轴力影响规律的基础上认为，在锚杆杆体总长度一定的情况下，减小内锚固段长度，可有效控制杆体轴力的增大。基于预应力锚杆加固围岩的组合拱理论，利用FLAC3D数值模拟技术，分析内锚固段长度对锚杆的预应力场及围岩支护效果的影响，结果表明：内锚固段长度的降低，有利于扩大锚杆的预应力场影响范围、提高围岩有效承载圈厚度、减少围岩塑性区深度和变形量。最后，讨论了通过改变锚固长度协调支护刚度的工程意义。

This paper aims to study the effect of the interior bonding section length on axial force of prestressed anchor rod and its supporting effect on surrounding rock. In this study, the ratio of interior bonding section length to total length of anchor rod is defined as interior bonding section length coefficient. Based on the equation of the shear stress of anchorage interface, an expression is deduced, which describes the relationship between the axial force and total extensional length of anchor rod. Then the effect of the interior bonding length coefficient on axial force of prestressed anchor rod is analyzed, and it is found that axial force of anchor rod increases with decreasing the interior bonding section length. According to the combined arch theory of prestressed anchorage, the influence of the interior bonding length of prestressed anchor rod and its supporting effect are studied by using the FLAC3D numerical software. The results show that the decrease of the interior bonding section length is beneficial to enlarging the influence scope of prestress field, increasing the thickness of the ‘effective load-bearing ring’ and minimizing the depth of plastic zone and deformation of the surrounding rock. Finally, changing interior bonding section length is significant to coordinate the support the stiffness of supporting structure in engineering.