浅埋黄土隧道衬砌结构受力分析

 通过对三十里铺隧道的现场测试，研究浅埋黄土隧道一衬和围岩接触应力、锚杆轴力、喷射混凝土表面应变、二衬中钢筋应力和浇注混凝土应变随时间变化规律及分布特征。结果表明，围岩释放应力最大值在7～10 d，位置在拱腰处；锚杆轴力稳定时间为30 d左右，且在空间上出现压应力区；喷射混凝土表面应变较大且常出现跳跃性变化；二衬钢筋应力初期为拉应力；边墙处的稳定时间为6～8 d后，拱顶处30 d后仍然递减；二衬混凝土应变由初期的拉应变向压应变变化。隧道衬砌的受力分析结果为支护系统的优化提供依据，对同类工程的设计提供借鉴。

MECHANICAL CHARACTERISTICS OF TUNNEL LINING STRUCTURE IN SHALLOW-BURIED LOESS AREA

By the in-situ test of Sanshilipu tunnel，the mechanical characteristics of tunnel lining in shallow-buried loess are studied，such as the spatial distributions and temporal changes of surrounding rock pressure，bolt axial stress，surface strain of shotcrete，reinforcement stress and concrete strain in secondary lining. The results show that the maximum stress released in surrounding rock takes place in 7–10 days；the bolt axial stress stabilizes in about a month and in some area exist compression forces；surface strain of shotcrete is relatively great and fluctuates discontinuously；and the reinforcement stress in secondary lining is firstly tensile. The stress value gradually stabilizes in 6–8 days near side wall but continues decreasing near arch；and the strain in secondary lining changes from tensile to compressive states. The results provide support for optimization and give references to future design and construction.