Forward Modeling Of The Mechanical Mechanism Of Cracks On Tunnel Structures

The unpredictability of the failure of the structure remains to be the core part of the research in underground engineering considering the complexity of geological condition, structural design and construction, management and resilience analysis. Moreover, tunnel cracks and fracture is one of the major deficiencies of underground structure. The appearance and development of cracks can result in leakage and may thusly cause the failure of the structural stability. Therefore the transportation safety will be disturbed due to the ignorance of the deficiency.As a result, the major goal of this dissertation is to establish an effective correspondence between the cracks and their main causes. Briefly, the object is to find out the possible causes of cracks using the relative characteristics of cracks. The core part of this dissertation can be summarized as follows:because of the relatively better performance of the modeling of cracks testified by the comparison between ABAQUS-XFEM and ANSYS from the mechanism of cracking and an calculation example, ABAQUS-XFEM is therefore applied to conduct numerical simulation of several common deficiencies, and followed by the result of the crack features. Besides, the collection of the data of tunnel cracks can cast light on the classification of the causes of cracks. In this dissertation, mechanics-related causes and non-mechanics-related causes are used to classify the possible causes of cracks. The announced cracks are mainly categorized into two types, longitudinal and circumferential cracks, distributing in the relative parts of the tunnel. Generally, in the numerical simulation, a single assumed cause of tunnel deficiency basically lead to a single crack feature. However, different kinds of features may result in similar crack features. As a result, the core part of this paper relies on the digging of the correspondence between the observed crack features and the possible reasons.