锦屏水电工程预应力锚杆检验当中，实际张拉伸长值始终不能满足设计要求，为深入了解预应力锚杆实际伸长值变化规律，在加工车间和施工现场分别进行了自由段完全自由张拉试验和现场施工工艺张拉试验，前者锚杆体自由段处于最理想受拉状态，后者与实际施工工艺一致，试验过程中发现不同条件下锚杆伸长值变化规律复杂，并受施工工艺、锚杆材质、温度、张拉力等诸多因素影响。通过试验证明： 2类样品锚杆实际张拉伸长值均不能达到理论伸长值要求，但锁定拉力基本不受影响。因此，预应力锚杆张拉工序质量验收以控制张拉力为主，伸长值作参考能满足设计质量要求。

In the test of prestressed rock bolt in construction of Jinping Hydropower Station, the actual tensioning length could not meet the requirements. Free tensioning test on the free rock bolt section is carried out in the workshop, and construction tensioning test is carried out in the site, so as to obtain the variation rules of the tensioning length of prestressed rock bolt. The tests showed that the variation rules of the tensioning length of the prestressed rock bolt are complicated under different conditions, and can be affected by construction technologies, rock bolt material, temperature and tensioning force. The tests proved that the tensioning lengths of the rock bolts tested can not meet the theoretical requirements, but the locking capacity of the rock bolts is almost unaffected. Therefore, the control of the tensioning force of the prestressed rock bolts is the key in the control of the tensioning quality of the rock bolts, and the tensioning length can be regarded as the reference value.