SV波空间斜入射下沥青混凝土心墙响应特性及抗拉破坏评价研究

Response characteristics and tensile failure evaluation of asphalt concrete core wall under spatial oblique incidence of SV waves

地震波空间斜入射下沥青混凝土心墙响应和动态抗拉破坏研究存在较大不足。考虑SV波入射方位角和斜入射角的空间任意性,基于波场叠加原理构建了地基边界上非一致自由场,建立了SV波空间斜入射波动输入方法。基于试验结果建立了沥青混凝土瞬时抗拉强度随应变速率变化的经验公式,提出了依据瞬时拉应力和瞬时抗拉强度判别心墙单元抗拉破坏的新方法。分析了入射方位角、斜入射角对沥青混凝土心墙加速度、应力空间分布的影响规律,揭示了空间斜入射相对垂直入射造成心墙局部拉应力激增导致心墙破坏机理,论证了传统静态强度判别方法相对本文方法对心墙破坏判别的误差,明确了不同入射方式下心墙抗拉破坏区分布特征。结果表明:与垂直入射相比,空间斜入射下心墙水流向、坝轴向和竖向加速度最大增加54%,9.2倍和5.2倍,心墙拉应力最大增加14.2倍,忽略空间斜入射,会严重低估心墙加速度和应力响应。入射方向越偏向坝轴向且斜入射角越大,心墙迎波侧更容易发生拉裂破坏;传统静态强度判别方法,会造成心墙较大的拉裂破坏判别误差。

The existing researches on response and dynamic tensile failure of asphalt concrete core wall under spatial oblique incidence of seismic waves have great shortcomings.By considering the arbitrariness of SV-wave incident azimuth and oblique incident angles and constructing the non-uniform free field on foundation boundary based on the wave field superposition principle,an input method for spatial oblique incidence of SV waves is established.Then,an empirical formula for the change in instantaneous tensile strength of asphalt concrete with strain rate is established based on the test results.A new method for the safety evaluation of core wall based on instantaneous tensile stress and strength is proposed.Finally,the influences of incident azimuth and oblique incident angles on the acceleration and stress distributions of core wall are analyzed.The damage mechanism of core wall caused by tensile stress surge caused by spatial oblique incidence is revealed.Using the proposed method,the error of the traditional static strength judgment method for core wall damage is demonstrated.The distribution characteristics of tensile failure zone of core wall under different incident modes are clarified.The results show that compared with those under vertical incidence,the acceleration of core wall in water flow,dam axis and vertical directions can be increased by 54%,9.2 times and 5.2 times at most under spatial oblique incidence.The tensile stress of core wall can be increased by a maximum of 14.2 times at most.Neglecting the spatial oblique incidence severely underestimates the accelerations and stresses of core wall.The more the incident direction deviates to dam axis direction and the larger the oblique incident angle,the more easily the tensile failure at the wave-facing side of core wall occurs.The traditional static strength judgment method leads to a large error of tensile failure of core wall.