偏桥水电站引水隧洞K2＋010～+310地段位于节理发育岩体中，隧洞开挖后因没能及时支护引起岩体过度松弛，产生大量掉块现象。为保证隧洞的稳定性及基于工期的考虑，对该段隧洞的支护结构进行了优化设计，并采用国际广泛应用的离散单元法程序UDEC对该引水隧洞施工运营全过程进行了仿真模拟，探明了隧洞施工各阶段围岩内应力和位移分布，对支护结构优化设计进行了评估。同时，探讨了隧洞施工和运营全过程的离散单元法仿真技术。

K2＋010～+310 section of the diversion tunnel of Pianqiao Hydropower Station is located in heavily jointed rock mass. The surrounding rock mass has been greatly loosened and rockfall occurred due to delayed support after the excavation. In order to assure the tunnel stability and considering the tight construction period, the tunnel support is optimized and the worldwideused discrete element code UDEC is applied to simulate the complete tunnel construction and operation process so as to examine the stress and deformation distribution in rock mass at various stages of tunneling and to assess the optimized design of the tunnel support. Meanwhile, the simulation technology of tunneling and operation using UDEC is thus investigated.