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：与深埋隧道的分析相比，浅埋隧道的研究涉及诸多不同维度。其显著特征包括变形断面的非均匀形态，以及无法沿用部分简化假设——例如假定开挖周边应力均匀分布。由于隧道衬砌同时承受弯压组合荷载，浅埋隧道更易产生最终拉应力（此类拉应力在深埋隧道中不会出现），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，研究目的为分析开裂行为对浅埋隧道位移的影响，并通过三类不同模型模拟混凝土的力学特性：线弹性模型、粘弹性模型，以及考虑开裂效应的粘弹性模型。