Mechanical performance test and finite element analysis of prefabricated utility tunnel L‐shaped joint

Abstract

SummaryIn order to promote the industrial production of utility tunnel, based on the actual prefabricated utility tunnel engineering background, two types of precast L‐shaped joint with end boundary elements are experimentally studied. In this paper, two precast L‐shaped top plates with the haunch zone and two precast L‐shaped bottom plates without haunch zone were designed. These two types of specimen were tested to investigate the mechanical performance of precast L‐shaped joint under different load combination effects. There were no obvious phenomenon in the whole opening test, and the most unfavorable load combination was in the elastic stage. In the closed test, the average ultimate bearing capacity of the prefabricated top and bottom plant specimens decreased by 2% and 1%, respectively, compared with the cast‐in‐place specimens, and the average ductility coefficients of the top and bottom plates are 5.78 and 2.73, respectively. It is also found that the setting of the haunch zone can improve the bearing capacity. The bending capacity of prefabricated L‐shaped joints calculated by the Chinese code's recommended formula is conservative, and the ratio of the test value to the calculated value is about 1.5. Finally, the reinforcement arrangement of the prefabricated specimens in the closed test was optimized by finite element software. It can be considered that changing the diameter of the reinforcements in the concrete compression zone to 16 mm will not affect the mechanical properties of precast joints.