多级板块缝隙中脉动压力传播过程数值研究

NUMERICAL INVESTIGATION OF PRESSURE FLUCTUATIONS WITHIN CRACK LAYERS OF LOWER SURFACES OF SLABS

基于一维瞬变流模型，对高坝下游水垫塘内多级底板块缝隙层中的脉动压力传播机理进行了数值研究，详细地分析了不同板块缝隙层中脉动压力的变化特征，以便为水垫塘底板块的受力分析提供科学依据．

Fluctuating pressure and its propagation within cracks under bed slabs in a plungepool downstream of a high dam are two main factors which cause destruction and scour of bed slabs in a plunge pool. The impingement by a free jet on the slabs in a plunge pool downstream of a large dam creates intense pressure flutuations within the cracks under slabs and causes the bed slabs to be unstable.The instantaneous differences of pressure on the upper and the lower surfaces of bed slabs can generate transient uplift forces, which loosen the bed slabs and cause them to move and vibrate within their matrix. Finally, when the uplift forces are larger than the sum of the drag forces andweights on bed slabs, the bed slabs are swept away.Based on one-dimensional model of transient flow and the characteristic method, the transmission of fluctuating pressures within cracks under many slabs in a plunge pool downstream of a high dam is investigated numerically. Characteristics of pressure fluctuations within crack layers of lower surfaces of different slabs are obtained, which provides a scientific basis for design of concrete slabs in a plunge pool. l) The project supported by the National Natural Science FOundation of China.