输水隧洞灌浆式预应力衬砌结构承载机理研究

输水隧洞双层混凝土衬砌之间采用预应力灌浆可以提高结构的承载能力，但此类灌浆式预应力衬砌结构的承载机理尚未得到系统阐释。基于弹性理论，采用荷载结构法，建立了考虑变形协调关系的灌浆式预应力衬砌力学分析模型。通过对衬砌结构的受力分析，揭示了预应力灌浆提高衬砌结构承载力的机理，推演了衬砌结构环向拉应力判定式，以及环向抗拉强度与灌浆预应力的关系式。利用有限元数值模拟验证了理论方法的合理性，针对工程案例分析了灌浆预应力对衬砌结构的定量影响规律。结果表明:结构能承担的最大内水压力与灌浆预应力及外部水土压力，均近似呈线性正相关，内衬结构的径向变形和环向应力随灌浆预应力的增大而减小，外衬结构的径向变形和环向应力随灌浆预应力增大而显著增大。这种考虑临界情况的分析和计算方法，揭示了灌浆式预应力衬砌结构的承载机理，可为该类型输水隧洞的力学分析和结构设计提供理论依据。

Study on bearing mechanism of grouting prestressed lining structure of water conveyance tunnel

Prestressed grouting between double-layer concrete linings of water conveyance tunnel can improve the bearing capacity of the structure, but the bearing mechanism of this kind of grouting prestressed lining structure has not been systematically explained. Based on the elastic theory, the mechanical analysis model of grouted prestressed lining considering the deformation coordination relationship is established by using the load structure method. Through the stress analysis of lining structure, the mechanism of prestressed grouting to improve the bearing capacity of lining structure is revealed, and the judgment formula of circumferential tensile stress of lining structure and the relationship between circumferential tensile strength and grouting prestress are deduced. The rationality of the theoretical method is verified by finite element numerical simulation, and the quantitative influence law of grouting prestress on lining structure is analyzed according to engineering cases. It is found that the maximum internal water pressure that the structure can bear is approximately linearly positively correlated with the grouting prestress and external water and soil pressure. The radial deformation and circumferential stress of the inner lining structure decrease with the increase of grouting prestress, while the radial deformation and circumferential stress of the outer lining structure significantly increase with the increase of grouting prestress. This analysis and calculation method considering critical conditions reveals the bearing mechanism of grouting prestressed lining structure, which can provide a theoretical basis for the mechanical analysis and structural design of this type of water conveyance tunnel.