Research On Characteristics Of Fluctuating Pressure In The Gap Under The Floor Of Special-Shaped Plunge Pool

The amount of water that can be developed and construction scale ranks first in the world. These projects in flood energy dissipation process due to the high head, flow, resulting in energy dissipation flood protection dam safety problem is very prominent. In order to achieve energy dissipation and scour purposes, mostly downstream of the dam within a certain distance up the river with concrete protection, and the construction of two dams on the downstream channel in place, part of the flood discharge energy dissipation structures-plunge pool.Due to the complexity and high speed flow stream generated by the gap, stilling pond dam safety protection structure has been a hot issue in the field of hydraulic engineering safety studies. Which the protective body structure optimized to achieve increased resistance to buckling one purpose is to improve the discharge capacity of the structural safety methods, optimized design have been proposed based on flat floor, anti-arched floor, Permeable floor and with keyway form. This paper presents a special-shaped structure plunge pool that the floor with keyway plus permeable porous structure. In the context of model test of Xiangjiaba plunge pool, based on the model test results, using a variety of signal processing techniques studied on the characteristics of fluctuating pressure acting on the gap of special-shaped plunge pool bottom, the main achievements and research of this paper include as follows:(1) Study on the propagation characteristics of fluctuating pressure of keyway bottom in the case of a single plate. Combined with the physical model test results of Xiangjiaba plunge pool, analysis of the pulsating pressure of the plunge pool on the bottom floor at the upper and lower surfaces and the vertical gap at the pulsating pressure size distribution before and after the addition of the keyway, and frequency domain characteristics and pulsating pressure and related properties. The results show that the maximum possible uplift of fluctuating pressure with keyway bottom is smaller than the bottom of without keyway. After adding the keyway surface space and time scale increases and increases the possession of a vortex, strengthen the connection between the plates.(2) Study on the influence of sealing gap width on fluctuating pressure. Ensure the floor and bedrock gap unchanged, changes the sealing gap between the plates. The results show that with the increase of water gap, produces a fluctuating uplift is reduced, is conducive to the plate stability; with the decrease of water gap, frequency shifts toward low frequency, dominant frequency band becomes narrow, focuses on 0.1Hz.(3) Study on the influence of floor pulsating width on fluctuating pressure. Combined with Xiangjiaba physical model test, to ensure the floor and the bottom sealing gaps remain unchanged, changes floor and basement cracks. The results show that: with the increase of the gap thickness, surface measuring points under the mean variance decreases; the lower surface of the measuring point integral time scale increases, the rate of increase in holdings of vortex.(4) Study on the structure stability of the special-shaped bottom. Additional keyway on the plate and arranged some open porosity permeable holes, comparative analysis of the similarities and differences of special-shaped bottom and ordinary water plunge pool on uplift force characteristics under the impact of the role of the high-speed flow. Thus explained special-shaped structure plunge pool can greatly improve the stability of the structure. The results show that the surface pressure coefficient ripple shaped structure under the bottom plate is less than the pressure coefficient of surface fluctuation general construction under the plate. Special shaped concrete slab can effectively reduce the fluctuation of flow energy, integrate the pervious slab and keyway bottom advantage, obviously improve the plate stability.