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During the construction of concrete ship locks, prolonged interruptions between the casting of the floor and lock wall are inevitable. In terms of mass concrete, long placement delays are one of the major reasons for the presence of cracks in newly placed concrete. Therefore, this study examines both the placement and structural characteristics of ship locks after long casting interruptions based on the mass concrete thermal stress theory to determine the major causal factors for cracks in newly poured concrete. Specifically, a block placement method is proposed to reduce thermal stress in newly placed concrete, and the temperature control and crack prevention capacities of the proposed method are verified using the finite element method. The development of the structure's thermal stress under different temperature control measures is analyzed, finding that thermal stress in the lock walls can be effectively reduced by 50% through low-temperature block casting. The results demonstrate that the proposed method can significantly reduce the internal thermal stress of newly placed concrete after prolonged casting interruptions, thereby highlighting its applicability for achieving effective temperature control and crack prevention in concrete ship locks. [ABSTRACT FROM AUTHOR]

High-pressure hydraulic fracture (HF) is an important part of the safety assessment of high concrete dams. A stress-seepage-damage coupling model based on the finite element method is presented and first applied in HF in concrete dams. The coupling model has the following characteristics: (1) the strain softening behavior of fracture process zone in concrete is considered; (2) the mesh-dependent hardening technique is adopted so that the fracture energy dissipation is not affected by the finite element mesh size; (3) four coupling processes during hydraulic fracture are considered. By the damage model, the crack propagation processes of a 1 : 40 scaled model dam and Koyna dam are simulated. The results are in agreement with experimental and other numerical results, indicating that the damage model can effectively predict the carrying capacity and the crack trajectory of concrete gravity dams. Subsequently, the crack propagation processes of Koyna dam using three notches of different initial lengths are simulated by the damage model and the coupling model. And the influence of HF on the crack propagation path and carrying capacity is studied. The results reveal that HF has a significant influence on the global response of the dam. [ABSTRACT FROM AUTHOR]