UHPC在隧道衬砌裂损整治中应用的可行性及性能要求研究

为解决隧道二次衬砌裂损整治中面临的净空限制等问题，提出采用超高性能混凝土（UHPC）代替普通混凝土作为衬砌补强材料，并对其可行性及材料力学性能要求进行系统研究。基于异性材料叠合梁理论对裂损衬砌和加固层的共同受力机制进行研究，得到加固材料的力学性能与结构受力特征之间的关系，从而得到加固工程对加固层厚度及UHPC力学性能要求； 在此基础上，提出一种实体单元应力和内力换算的计算方法，并通过有限差分法数值模拟，对衬砌与加固材料之间结合面的受力特征进行分析，从而得到加固工程对UHPC和普通混凝土之间黏结强度的要求。研究结果表明： 对于承载力损失不超过40%的衬砌，可采用UHPC进行加固； 对于承载力损失不超过15%的衬砌，UHPC的使用可将加固层的厚度减小到10 cm左右。

Feasibility and Performance Requirements of Ultra High PerformanceConcrete in Crack Treatment of Tunnel Lining

The headroomlimit always restricts the crack treatment of tunnel secondary lining.Accordingly, ultra high performance concrete(UHPC)is proposed to replace ordinary concrete as a lining reinforcement material,and the feasibility and performance requirements of UHPC application areexamined systematically. Based on the composite beam theory of dissimilarmaterials, the joint stress mechanism of a cracked lining and reinforced layeris studied. The relationship between the performance parameters of thereinforced material and the mechanical characteristics of the structure isobtained. Thus, the requirements of reinforcement layer thickness and themechanical properties of UHPC are obtained. On this basis, a calculation methodfor converting between the stress and internal force of solid elements isproposed, and the stress characteristics of the joint surface between thelining and reinforcing materials are analyzed using a finite differencenumerical simulation method. Consequently, the requirement of bond strengthbetween UHPC and ordinary concrete is obtained. The results indicate thefollowing: (1) For linings with a bearing capacity loss of less than 40%, UHPCcan be used for reinforcement. (2) For linings with no more than 15% bearingcapacity losses, UHPC can reduce the thickness of the reinforced layer to about10 cm.