Dynamic-Response Analysis of the Branch System of a Utility Tunnel Subjected to Near-Fault and Far-Field Ground Motions in Different Input Mechanisms

• Published in: Computer modeling in engineering & sciences Vol. 130; no. 1; pp. 167 - 186
• Main Authors: Jin, Yuhang, Guo, Endong, Wu, Houli, Yan, peilei
• Format: Journal Article
• Language: English
• Published: Henderson Tech Science Press 2022
• Subjects: Earthquake damage; Earthquakes; Equivalence; Far fields; Finite element method; Ground motion; Mathematical models; P waves; Pipelines; Seismic response; Tunnels; Typhoons; Underground structures; Vertical motion
• ISSN: 1526-1506; 1526-1492; 1526-1506
• DOI: 10.32604/cmes.2022.018113

There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures, especially for the branch joint of a utility tunnel (UT) and its internal pipeline. Based on the theory of a 3D viscous-spring artificial boundary, this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program, which was applied to an ABAQUS finite element model. Based on near-fault and far-field ground motions obtained from the NGA-WEST2 database, the dynamic responses of a utility tunnel and its internal pipeline in different input mechanisms of near-fault and far-field ground motions were compared according to bidirectional input and tridirectional input, respectively. Generally, the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion, and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel. In addition, the joint dislocation of the upper and lower three-way joints of the pipeline in the branch system under the seismic action led to local stress concentrations. In general, the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline from damage during the rare earthquake.