Study On Decompression Mechanism Of The Pervious Slabs In Special-shaped Plunge Pool

With the development and utilization of hydropower resources,large numbers of water conservancy project are or will be built.Due to the complexity of high speed flow,it is a difficult problem for the researchers to ensure the safety of the plunge pool.In order to protect the downstream of the dam,different plunge pool protective structures are built to make the first defence line.With the expansion of water conservancy project,the unfavorable factors of mass concrete structure are growing.So,many researchers constantly explore the new ideas of research,such as anti-arched floor,permeable floor and with keyway form,In the context of model test of Xiangjiaba plunge pool,and based on the model test results,this paper studied on the characteristics of pervious slab with keyway,thereby,studied on decompression mechanism of pervious slabs in special-shaped plunge pool.The main contents and results as follows:(1)Study on the propagation characteristics of fluctuating pressure of pervious slab with keyway.Based on the model test results,the paper makes analysis of pulsating pressure,frequency domain characteristic and related properties on the upper and lower surfaces and vertical gap of the pervious bottom floor.The results show that: after making permeable porous,the maximum uplift of fluctuating pressure and fluctuating pressure intensity coefficient are smaller.When H is 95 m,the changing of fluctuating pressure intensity coefficient on the bottom points is more than 30%.The probability density distribution has no change.The correlation among the measuring points is smaller.It shows that the permeable porous make the floor structure more stability.(2)Study on the hydrodynamic load characteristics of slabs with keyway.The results show that: after adding keyway,it reduces the maximum force and the fluctuating lift force on the slabs.But the probability density distribution has no change.The frequency of uplift force shifts toward low frequency.(3)Study on the permeable to the influence of the hydrodynamic load characteristics.The results show that: the maximum force and the fluctuating lift force have more reduced.It shows that keyway and permeable work together to make the stability of the slabs.The probability density distribution has no change.Based on the predecessors' research,the maximum force and fluctuating uplift force have the maximum force and fluctuating uplift force have the quantitative relationships.It is 3 times for impermeable slabs with keyway,and 4 times for permeable slabs with keyway.(4)Study on the structure stability of permeable slabs with keyway.With the impact of high-speed flow,water dynamic load characteristics are analysid between permeable slabs and the flat slabs.The results show that compared to impervious slab,corresponding pressure fluctuations spectral density of pervious slab is reductive.Thereby,it can reduce the energy on crack.The keyway and permeable have comprehensive advantages which is beneficial to the stability of the base plate.