Cause Investigation of Fractures in the Anti-Arc Portion of the Gravity Dam’s Overflow and the Top of the Substation Tunnel

Clarifying the origins of fractures and adopting acceptable repair plans are crucial for the design, maintenance, and safe operation of concrete gravity dams. In this research, numerical simulation is largely utilized to investigate the reasons for fractures in the anti-arc portion of the concrete gravity dam and the top of a substation tunnel in Guangdong Province, China. The calculation parameters are chosen based on the design information and engineering expertise to model the temperature field and stress field distribution of the dam during both normal operation and severe weather. The study demonstrates that under the effect of severe structural restraints and high temperatures, the tensile stress at the top of the substation tunnel would be 2.64 MPa in the summer, which is more than the tensile strength by 1.5 MPa and causes deep cracks. The tensile stress reaches 3.0 MPa in the summer under the effect of severe weather near the top of the substation tunnel. When a cold wave strikes in the winter, the concrete’s tensile stress on the overflow dam surface rises from 1.6 MPa to 4.0 MPa, exceeding the tensile strength by 1.9 MPa, resulting in the formation of a connection fracture in the reverse arc section. Both the actual observed crack location and the monitoring findings of the crack opening, as determined by the crack gauge, agree with the modeling results. The technique to lessen the structural restrictions of a comparable powerhouse hydropower station is pointed out based on engineering expertise, and various and practical repair strategies are proposed to guarantee the structure’s safe operation.

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