Improvement Methods for Reduction of the High Stress of Ultra-High Asphalt Concrete Core Dams

Abstract

With the rapid development of asphalt concrete core rockfill dams (ACCRDs), the construction of ultra-high asphalt concrete core rockfill dams (UACCRDs) has been improved significantly. However, the security problems of asphalt concrete core (ACC) become very prominent with the increase of dam height. The shear failure control standard and tensile failure control standard of ACC are suggested. The mechanisms of ACC that generate high shear stress and high tensile stress are investigated. Based on the definition of stress level and the transmission mechanism of arch structures, the improvement methods that reduce the high shear stress and high tensile stress of ultra-high asphalt concrete core (UACC) are proposed and investigated. The results show that the stress level of ACC can be reduced significantly by the increase of the strength parameters of ACC (failure ratio, cohesion, and internal friction angle). The following value ranges of the failure ratio, cohesion, and internal friction angle of ACC for the suitable construction of UACCRDs are recommended: Rf ≥ 0.75, C ≥ 0.30 MPa, and φ ≥ 28.5° (h = 150 m), with the growth gradient adjusted by 5%, 15%, and 5%/25 m. The tensile stress and tensile stress area can be reduced obviously by the new type of dams (curved asphalt concrete core rockfill dams (CACCRDs)). The value ranges of the curvature of CACC (k ≥ 1.0 × 10−3) for the suitable construction of UACCRDs are recommended.

Influence of joint form on shear characteristics of asphalt concrete core under steep bank slope condition

“…The calculation results show that as the slope of the left bank becomes steeper, the stress level and shear stress S13 component of the core decrease. The maximum stress level is located in the left bank near the bottom area, and there is also a large area of high stress level in the middle of the right bank, which is consistent with the conclusion of the reference [30] . The rock on the left bank is steep and the core has a large misalignment along the bank slope.…”

“…The study shows that there is a signi cant shear effect between the core and the bank slope due to the constraints of the valley terrain. In order to quantify the magnitude of shear action, [12] proposed the shear safety control standard of ACC based on the stress characteristics of ACC in different periods. In general, the current research on ACCRDs at home and abroad is mainly aimed at the general valley terrain, and there are few studies on the impermeability and safety of the joint between the asphalt core and the base under the condition of high-steep bank slopes.…”

“…Its mechanical properties need to comprehensively consider the combined effects of its own load (self-weight) and surrounding structures (friction, earth pressure, water load, etc.) [12] . When analyzing the mechanical properties of ACC, it is necessary to comprehensively consider the combined effect of transition layer and rigid contact.…”

Evaluation of the Effect of Varying the Angle of Asphaltic Concrete Core on the Behavior of the Meijaran Rockfill Dam

“…Moreover, some researchers have recently used FEM for identifying the static and dynamic behavior of an asphaltic concrete rockfill dam [20,21]. Wu et al (2018) found that the stress distribution and deformation of the asphaltic core are appropriate during the completion and operating stages and do not cause shear failure in the asphaltic core or hydraulic failure.…”