路基施工对下埋引水隧洞受力特征的影响

以某高速公路路基施工为对象，采用数值方法研究了不同工况下，填方加载、挖方卸载对既有引水隧洞的不利影响，获取了隧洞的力学特征，对比分析了填方加载后隧洞的三种加固方案，即内衬钢板、灌浆固结、灌注桩+系梁。结果表明:内衬钢板方案加固效果好，经济合理灌浆固结对软岩加固效果不佳；灌注桩+系梁框架结构将承担部分上部荷载，加固后隧洞应力值减小约50%。深挖卸载将导致隧洞底板最大拉应力由点至面分布，但应力最大值与开挖前几乎一致。最后，计算了深挖路堑爆破药量及安全距离。

Influence of Subgrade Engineering on the Mechanical Characteristics of Water-diversion Tunnel

Taking the subgrade construction along a highway as an example, herein numerical method was used to study the adverse effects of fill loading and excavation unloading on the existing water-diversion tunnel under different working conditions, and then to get the mechanical characteristics of the tunnel; moreover, three reinforcement schemes for the tunnel after fill loading, including inner steel lining, grouting consolidation and cast-in-place piles plus tie beams, were compared. The result shows that grouting consolidation is unsatisfactory effect on soft rock reinforcement, cast-in-place pile plus tie beam frame structure bears part of upper load so that the stress value of the tunnel reinforced is reduced by about 50%; inner steel lining is effective with reasonable cost. Deep cut for unloading would cause the maximum tensile stress of the tunnel floor to be distributed from point to plane, but the maximum stress value was almost the same as before. Finally, the blasting charge and safety distance of the deep excavation slope were calculated.