中文摘要：

针对大秦线盖板涵底部直线体外预应力加固方式,利用体外预应力筋的应力增量与盖板涵跨中挠度和混凝土压应变的相互关系,分别按考虑和未考虑体外预应力筋反弯矩对盖板涵截面转角和挠度关系的影响,推导体外预应力筋应力增量以及盖板涵截面强度和刚度的计算式,并进行了室内试验验证。结果表明：进行加固盖板涵的体外预应力筋应力增量计算时必须考虑反弯矩的影响;盖板涵截面压应力、受拉钢筋拉应力、跨中挠度的理论计算结果与试验结果基本相同,验证了推导的理论计算方法是正确的;相比在一定范围内改变预应力筋与盖板涵底的距离及锚固位置,增大体外预应力筋的截面面积和有效预应力可明显提高盖板涵截面的刚度和强度;当荷载为75kN·m-1时,与采用16mm体外预应力筋加固相比,采用32mm体外预应力筋加固后盖板涵混凝土上表面的压应力减小10.5%,跨中挠度减小44.1%;有效预应力从15kN增大到135kN,加固后盖板涵混凝土上表面的压应力减小15.5%,跨中挠度减小37.7%。

英文摘要：

According to the reinforcement method of straight line external prestressing for slab culvert of Datong-Qinhuangdao line and by using the mutual relations between the stress increment of externally prestressed tendon,the mid-span deflection of slab culvert and the compressive strain of concrete,under the two conditions of considering and without considering the influence of the negative bending moment of externally prestressed tendon on the sectional angle and deflection of slab culvert,the calculation formulas for the stress increment of externally prestressed tendon,and the section strength and stiffness of slab culvert were deduced and were verified by indoor experiments.Results show that the influence of negative bending moment must be considered in calculating the stress increment of the externally prestressed tendon of reinforcement slab culvert.The theoretical calculation results and test results are nearly the same for the section compressive stress,the stress in tensile reinforcement and the mid-span deflection of slab culvert,which indicates that the deduced theoretical calculation method is accurate.Compared to changing the distance between the prestressed tendon and the bottom of slab culvert and anchorage position within certain range,increasing the section area of externally prestressed tendon and effective prestressing can obviously increase the stiffness and strength of slab culvert section.As the load is 75kN·m-1,compared with the externally prestressed tendon reinforcement of16mm,the compressive stress on concrete surface of slab culvert with the externally prestressed tendons reinforcement of32mm decreases 10.5%,mid-span deflection decreases 44.1%.After the effective prestressing increases from 15 to 135kN,the compressive stress on concrete surface of reinforcement slab culvert decreases 15.5%,mid-span deflection decreases 37.7%.