Field Testing Study On Pile Hydrodynamic Characters Of Inland River Suspended Vertical Wharf

Mountainous river have jet velocity and steep slope, which also have large variation range of water level. The overhead port with high structure and large diameter and multilayer freely contact support get large and complex water force. The existing “Code for Loads of Port Engineering”(JTS144-1-2010) has been unable to meet the calculation of this structure of the force of water flow. To accurately calculate the force of water flow of overhead port, this project based on early experiment of this topic and relying on the wharf engineering has redesigned the experiment scheme once again and improved system of dynamic water testing and data processing method, further analyzed and studied the hydrodynamic characteristics of single pile, steel braces, bent, and group pile based on“Study on key technique of wharfs construction in canalized reach in mountain rivers”(2012BAB05B04). Main research contents and innovations are as follows:(1) Improve the test system of hydrodynamic characteristics and optimize experimental program based on the preliminary tests. A total of 17 sets of test systems were developed to carry out field tests on the wharf. And the water instantaneous pressure data were collected, obtaining more than 100 million valuable experimental data.(2) Based on stochastic process theory, mathematical statistics and application of auxiliary calculation software such as MATLAB, ORIGIN, a set of the feasible method for analyzing hydrodynamic pressure was performed, including calibration and conversion of data, outlier adjustment, frequency domain analysis, digital filtering, time-domain statistical analysis, calculation of hydrodynamic pressure. After the data processing, the instantaneous pressure signal, the hydrodynamic pressure sample and the eigenvalues of each single point under different conditions were obtained.(3) Flow velocity, water depth and flow angle have certain influence on the dynamic characteristics of a single positioning: there is a certain proportional relationship between flow velocity and flow turbulence intensity, that is, as the flow rate increases, the flow turbulence intensity tended to increase. With water depth increase, the flow turbulence intensity and flow resistance of individual locations increase first, then decrease, and increase again. This change has roughly corresponding relationship with the relationship between flow velocity and water depth.(4) With solution of flow resistance acting on single pile under different flow rates,mountain river flow resistance coefficient, approximately 0.30 to 0.40, is obtained by further calculation.(5)Flow around pile group, subject to the mutual interference between the flow field around pile foundation, the average and amplitude of dynamic water pressure acting on parallel piles first decrease and then become steady from the middle of river to river bank direction. On longitudinal direction, the flow wake and cover of front pile have influence on the flow flied of second pile of intandem piles. And the surrounding water became chaotic, turbulent intensity increased. The turbulent intensity around the fourth pile became decrease because of the vortex shedding and energy weakening. Under the influence of flow around horizontal brace and pile foundation in front, average dynamic water pressure on the pier longitudinal steel spreader surface has a decreasing trend after increased first,and average dynamic water pressure and the amplitude in flow front point are maximum,the flow turbulence is strongest.