大型薄壁输水渡槽流固耦合振动台试验研究

Experimental study of dynamic interaction between large thin wall aqueduct and water

地震高烈度区大型高架渡槽的抗震安全是我国西南地区长距离调水工程建设及运行过程中难以回避的重大挑战。渡槽结构与槽内水体动力相互作用是地震响应分析及安全评价的关键问题。目前使用较多的将水体以附加质量方式计入其对结构动力响应影响的方法是基于刚性壁与流体相互作用假定下推导建立的。大型渡槽多为薄壁结构,柔性结构与水体间的动力相互作用与刚性壁假定存在明显的不同。本研究采用几何比尺1/10的大型薄壁渡槽物理模型,通过振动台试验研究渡槽与水体的动力相互作用。通过深入分析稳态白噪声激励和11组双方向地震波激励下渡槽结构的动态响应,确定大型薄壁渡槽中水体对结构自振频率及渡槽两端支座力产生的重要影响,并给出了试验对象渡槽结构槽内水体与渡槽动态相互作用的等价质量定量关系。为实际工程抗震设计准确分析评价渡槽抗震安全提供可靠依据。

It is an unavoidable challenge to guarantee the seismic safety of large aqueducts for long distance water transmission projects in Southwest China, where the seismic intensity is very high and earthquakes are very frequent. The dynamic interaction between structure and water is the critical problem in numerical procedure for the estimation of seismic responses and safety verification of aqueducts. Added mass method is widely used to simplify the structure-water interaction, which is deduced based on the rigid wall assumption. Most of large aqueducts, however, are thin wall structure, evidently different to rigid wall. A physical model of 1/10 in geometrical scale, representing a large thin wall aqueduct, was used in our research to study the aqueduct and water interaction on a shaking table. With the analyses of the aqueduct responses to stationary white noise excitations as well as 11 sets of earthquake motions, the dynamic influence of the water on the eigen-frequencies as well as the reaction forces of seat of the aqueduct were clarified and the relation with the water mass was given quantitatively. These results can provide scientific basis for the numerical seismic analysis of the proto structure where the dynamic interaction between aqueduct and water has to be treated properly.