隧道支护工字型钢与喷射混凝土粘结滑移性能研究

STUDY ON BOND-SLIP BEHAVIOR BETWEEN I-SHAPED STEEL AND SHOTCRETE FOR TUNNEL SUPPORT

工字型钢与喷射混凝土的粘结滑移性能对隧道初期支护的协同变形,整体承载能力具有重要影响。该文进行了自然粘结和焊接栓钉两组对照的推出试验,观察试件的破坏特征,获取粘结滑移曲线。在此基础上分析试件的粘结滑移性能,通过函数建立了自然粘结和焊接栓钉试件的粘结滑移本构模型,并提出了特征值的计算公式。试验结果表明:自然粘结试件的破坏模式为纵向劈裂破坏,焊接栓钉试件为拉裂破坏,拉裂缝位置沿栓钉横向排列方向;试件的荷载-裂缝宽度曲线与平均粘结强度-滑移曲线变化规律基本一致,可分为四段:无滑移段、斜线上升段、曲线下降段和水平残余段;在型钢腹板增加栓钉连接件,能有效提高型钢喷射混凝土的特征粘结强度。试验曲线与本构模型曲线对比拟合较高,表明该文提出的本构模型具有较高的精度。研究结果对于隧道工字型钢与喷射混凝土支护结构破坏特征研究及设计提供理论支持。

The entire bearing capacity and the synergistic deformation of the initial support of tunnel are significantly impacted by the bond-slip behavior between I-shaped steel and shotcrete.The push-out tests of natural bonding and welded studs were conducted to observe the failure characteristics of the specimens and obtain the bond-slip curve.On this basis,the specimen’s bond-slip behavior was analyzed,and the bond-slip constitutive models of natural bond and welded stud specimens were established.The calculation formula of eigenvalues was proposed.The test results exhibit that the failure mode of the natural bonding specimen is longitudinal splitting failure,the welding stud specimen falls in tensile failure,and the tensile cracks occur along the transverse direction of the stud.The specimen’s load-crack width curve is consistent with the average bond strength-slip curve,divided into four stages,i.e.,no slip stage,inclined upward stage,downward curve stage and residual horizontal stage.Adding stud connectors to steel webs can improve the characteristic bond strength of steel shotcrete.The fitting between the test curve and the constitutive model curve is high,indicating that the constitutive model proposed in this paper has high accuracy.The research results provide theoretical support for the research on failure characteristics and the design of tunnel I-shaped steel and shotcrete support structure.