Abstract
Due to the demand in flood season for power generation, the first-stage face slab of a high concrete-face rockfill dam often must be constructed ahead of schedule, and advanced water storage is needed for the reservoir. Since the dam-body filling has not yet been completed at this point, the internal stress of the first-stage face slab is more complicated than that of normal construction. Taking Buxi Power Station as an example, the first-stage face slab temporary construction seam showed large areas of shear stress damage during the rise in reservoir water levels during the second segment of the second construction stage. The concrete-face slab showed large-piece brittle bulging, and the steel rebar was exposed and developed contortional deformation. Based on the monitoring data for Buxi Power Station along with the first-stage fracture characteristics of Shuibuya concrete face, this paper applied a numerical analysis to conduct research on the causes of fracture mechanics. The results indicate that the cracks occurred on the face slab during the second segment of second-stage water storage primarily due to the advanced concrete pouring of the first-stage face slab; during the first stage of reservoir water storage, the internal stress of the first-stage face slab was not reduced or eliminated prior to second-stage face slab pouring. Thus, with the rise in the reservoir water level, the shear stress increased continuously, eventually leading to partial large-scale shear stress failure of the first-stage face slab. The research results provide important references for the design and construction of concrete-face rockfill dams.
Highlights
Concrete-face rockfill dams have advantages such as their large scale, low interior stress, and construction efficiency attributable to the use of large construction equipment [1, 2].erefore, the number of dams of this type is rapidly increasing
For the high concrete-face rockfill dam, due to the demand in flood season for power generation, the first-stage face slab must be constructed beforehand, and advance water storage is needed for reservoir [12,13,14,15]
For the 135.8 m Buxi and the 233 m Shuibuya concrete-face rockfill dam, before the dam body was completely filled to the top, the construction of the first-stage concrete slab and first-stage reservoir water storage had already begun
Summary
Concrete-face rockfill dams have advantages such as their large scale, low interior stress, and construction efficiency attributable to the use of large construction equipment [1, 2]. In the advance construction of the first-stage face slab and reservoir water storage, due to the influence of water pressure at the Advances in Civil Engineering reservoir water level along with settlement and deformation in the interior of the rockfill mass, the internal stress of the concrete slab will undergo certain changes. Shuibuya shows no large-scale shearing failure, the cracks in the upper and lower layer appear in the relatively concentrated region, and the cracks display an “I” shape [18] Both slabs present concentrated crack regions with limited width at the top and bottom [7, 19]. Based on the above description and the monitoring data of the slab for Buxi Power Station, this paper used a comparative analysis method that applies Ansys finite element software to conduct mechanical-cause research on the slab cracks at Buxi Power Station to determine the cause of brittle failure of the first-stage slab during advance construction and reservoir water storage, presenting design ideas along with corresponding structural measures to prevent the occurrence of cracks [21]
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