拱坝振动台动力破坏试验研究

水电资源富集而高烈度地震频发的西南、西北地区的水电建设在西部大开发和全国能源合理配置中具有举足轻重的战略地位,而高拱坝抗震安全是西部水电开发建设的关键技术之一。针对拱坝在强地震动作用下的动力响应和损伤破坏过程,进行振动台模型试验研究。试验模型最大限度地模拟影响拱坝地震响应的各种主要因素,包括坝体—基础—库水间动力相互作用,坝体构造横缝,坝肩关键滑裂体,动态能量辐射等。模型坝体材料采用自然干燥粉状材料加压制成,满足模型强度相似要求。在逐级增加的输入地震作用下坝体共发生11处可确认开裂损伤,但未出现受压破坏。试验模拟呈现拱坝在地震作用下的响应及其损伤破坏过程,确定抗震薄弱部位,为全面定量评价拱坝的抗震性能提供重要依据。

Experimental study on the dynamic failure of arch dams using a shaking table

Seismic safety of large arch dams presents a difficult design problem,constituting one of the greatest challenges in the development of hydropower in the southwest and northwest areas of China.The seismic safety of a large arch dam was studied through a shaking table experiment.The model system included a scaled arch dam(with contraction joints),part of the reservoir,part of the foundation rock mass with topographic features near the dam and key potential wedges around the abutments.A damping boundary consisting of viscous fluid was employed to simulate the effect of dynamic energy transfer to the far field,in order to characterize the dynamic interactions between the dam and the foundation.A new model material was employed to meet the requirement in strength similitude.The characteristics of major sliding planes near both abutments were carefully studied.Eleven overstressed or cracked locations were identified under strong seismic motions of different levels,with the largest being 6.5 times that of the design level.The dynamic characteristics of the arch dam system as well as its weak portions during earthquakes were discussed.