The Spatiotemporal Distribution Characteristics and Sensitivity Analysis of Stress in the Galleries of a Super-High Arch Dam During Construction

In recent years, construction has started on several high arch dams in the southwestern region of China, and the problem of concrete crack prevention has become prominent. During the construction period of the foundation gallery of high arch dams, the stress is high and there are many influencing factors, making it more prone to cracking, and there is relatively little systematic research on this issue. This article focuses on the cracks in the 733 m gallery of the 7th section of a super-high arch dam. Using self-developed 3D finite element software, the stress spatiotemporal distribution and influencing factors during the construction period were analyzed. Research has shown that a decrease of 4 °C in the average annual temperature inside the gallery results in an increase of approximately 0.25 MPa in surface stress on the arch and bottom plates. When poured to an elevation of 870 m, the circumferential stress caused by the self-weight on the arch of the gallery is 2.3 MPa, but it decreases to 0.9 MPa at a distance of 0.3 m from the surface of the arch. The stress at both ends of the bottom plate before and after the arch sealing is always greater than that in the middle, with a maximum stress of about 2.4 MPa. The selection of material parameters has a significant impact on the evaluation of crack resistance. When calculating the mechanical parameters of fully graded concrete, the crack resistance safety of the arch crown and bottom plate is significantly reduced. It is recommended to focus on strengthening the water cooling and “winter period” insulation measures for the arch crown and bottom plate during gallery construction and to use fully graded test parameters in simulation analysis to improve calculation accuracy and structural safety. The research results can provide reference for similar projects.