Influence of the cracking consideration in the displacements of a shallow tunnel lined in steel-reinforced concrete: numerical model

abstract: The study of shallow tunnels introduces different aspects when compared to deep tunnels analysis. Among these characteristics can be emphasized the non-uniform shape of the deformed cross-section and the impossibility of some simplifications such as the consideration of homogeneous stresses around the excavation. Since the tunnel lining is subject to combined bending and compression, shallow tunnels are more susceptible to the development of final tensile stresses (not founded in deep tunnels) and the consequent concrete cracking. This paper presents a numerical simulation in finite elements with the ANSYS software. The purpose of the study is to analyze the cracking influence in the displacements of shallow tunnels, treating the concrete behavior by three different models: elastic, viscoelastic and viscoelastic with cracking effects.摘要：与深埋隧道分析相比，浅埋隧道的研究涉及诸多独特的方面。其中可重点关注的特征包括：变形断面的非均匀形态，以及无法采用诸如开挖周边应力均匀化这类简化假设。由于隧道衬砌承受弯压联合作用，浅埋隧道更易产生最终拉应力（深埋隧道中不会出现此类拉应力），进而引发混凝土开裂。本文采用ANSYS软件开展有限元数值模拟。本研究的目的在于分析开裂行为对浅埋隧道位移的影响，通过三种不同模型模拟混凝土的力学特性：弹性模型、粘弹性模型，以及考虑开裂效应的粘弹性模型。