GFRP筋连接钢-混凝土复合衬砌斜接缝抗弯刚度试验研究

Experimental Study on Bending Stiffness of Oblique Seams of Steel-Concrete Composite Lining Conrected by GFRP Bars

为避免隧道冰冻暗挖法施工弊端和灾害,首次提出盾构直接切削式GFRP筋连接钢-混凝土复合衬砌。钢混复合衬砌刚度分布十分不均匀,考虑GFRP筋低弹模变形,其斜接缝为管片刚度最薄弱点。基于钢混复合衬砌管片斜接缝荷载试验,分析多因素下交界面抗弯刚度变化规律。通过接缝处弯矩转角试验曲线回归分析推导建立了接缝抗弯刚度计算公式。结果表明:钢混交接斜接缝抗弯刚度为非线性和线性两阶段模型,随着接缝弯矩增大抗弯刚度逐渐趋于稳定。接缝处轴力作用能显著提高初始抗弯刚度,而GFRP筋初始松弛和低弹模变形增大了接缝转角,从而削弱了接缝抗弯刚度。轴力作用下,接缝抗弯刚度随偏心距增大而减小。

In order to avoid the disadvantages of tunnel construction by frozen digging,steel-concrete composite lining connected by GFRP bars in shield cut is proposed firstly in this paper.The distribution of steel composite lining stiffness is uneven,and its oblique seam is the weakest point of stiffness considering low elastic deformation of GFRP bars.Based on composite lining load experiments,change law of bending resistance at the cross interface under multi-factors is analyzed.Formula for calculating the bending stiffness of the seam is established by deriving the moment-rotation curve at the Fitted seam.The results show that the bending stiffness of the steel mixed-transition seam is a nonlinear and linear two-stage model,and the seam stiffness tends to stabilized with the increase of bending moment.At a same stress level,the axis force at the seam significantly improves the initial bending stiffness,while the large deformation of GFRP bars increases the seam angle and weakens the seam bending stiffness.Under the action of axial force,stiffness of the seam decreases with the increase of eccentricity.