SENSITIVITY ANALYSIS FOR AUTOGENOUS VOLUMEDEFORMATION’S INFLUENCE ON THERMAL CREEP STRESS OFXIAOWAN HIGH ARCH DAM

摘要

Autogenous volume deformation is an important parameter of evaluating concrete’srnanti-cracking behaviors. The maximum thermal creep stress of concrete arch dam appears in therndam center at the end of late-stage water pipe cooling. If the autogenous volume deformation is inrnthe stage of shrinking at the same time, it will superpose with the shrinkage deformation caused byrnconcrete’s dry-shrinkage deformation and temperature drop. That may make the thermal creeprntensile stress exceed concrete’s earlier tensile strength and thermal crack may appear. Contrarily,rnexpansion autogenous volume deformation can counteract part of shrinkage deformation and canrnbenefit the concrete’s anti-cracking quality. This paper adopts 3D FEM to analysis the influence ofrnautogenous volume deformation on Xiaowan concrete high arch dam’s thermal creep stress on thernbasis of simulation of 3D transient temperature field. When presuming autogenous volumerndeformation, earlier expansion concrete, earlier shrinkage concrete, delaying expansion concrete,rndelaying shrinkage concrete are considered. The results show that early expansion and earlyrnshrinkage concretes have obvious influence on the dam’s early thermal creep stress, however havernless influence on dam center’s maximum thermal creep stress. The longer of delaying expansionrnconcrete’s expansion period is, the smaller of dam center’s maximum thermal creep tensile stressrnand the final residual thermal creep tensile stress, which can benefit the concrete’s anti-crackingrnquality. While delaying shrinkage concrete has the contrary character. The shrinkage autogenousrnvolume deformation has distinct influence on the thermal creep tensile stress in dam heel and damrntoe, the longer of shrinkage period and the larger of shrinkage deformation are, the larger of thernthermal creep tensile stress is in dam heel and dam toe. In the case of material’s strength andrnlasting quality can be assured, the expansion period and expansion deformation should bernincreased properly so that to simplify temperature control measures, reduce cost and advance thernspeed of concreting.