Research On The Measurement Method Of The Bottom Damage Of The Stilling Basin

The stilling pool is an important part of the flood discharge and energy dissipation of hydropower dams,which can eliminate 40% to 70% of the kinetic energy of flood discharge,and its structural integrity directly affects the safety of the dam.When the stilling pool is built,it will often face crustal movement,flooding,and natural structural aging during its operation.Therefore,the bottom of the stilling pool will have cracks,pits,bulges,exposed tendons,abrasion and other damages during long-term operation.Therefore,it is very important to detect the damage of the bottom of the stilling pool.Traditional drainage detection and diver detection are gradually brought to an end under the impetus of smart power plants,smart monitoring,Internet accelerated speed and other technologies.The rise of smart robot technology and computer vision in the underwater inspection industry has set off a wave of underwater fine measurement.Starting from the need for three-dimensional information inspection of concrete defects at the bottom of the stilling pool of hydropower dams,the natural light in the muddy water environment at the bottom of the pool cannot be transmitted to the bottom of the stilling pool,the refraction distortion of waterproof camera imaging,and the two-dimensional image can not accurately reflect the stilling pool.The real damage of the bottom and other factors interfere with the visual measurement.For this reason,a three-dimensional visual measurement method for the bottom damage of the stilling pool is established.First,for the turbid water environment without natural light transmission,the Intel Real Sense SR300 depth structured light camera is used to build an underwater 3D point cloud acquisition module,and the module is placed in the "Clean Water-Replacement" module to eliminate the point cloud in the turbid water environment The interference of the collection realizes the acquisition of point cloud data in the underwater dull and turbid environment;then,the principle of refraction distortion of the underwater 3D point cloud is analyzed and the 3D model of non-parallel surface imaging is established,through the underwater non-parallel surface The construction of the multi-medium refraction distortion image model realizes the effective mapping between the point cloud and the model in the natural scene.Then,in view of the influence of the refraction distortion model on the imaging field of view,the parameter optimization method of the refraction distortion model is established.The degree of change retains the imaging field of view of the refraction and distortion 3D point cloud;finally,the underwater 3D point cloud refraction distortion correction algorithm is constructed using the imaging model after parameter optimization,and the distorted underwater point cloud data is restored to realize the correction in the turbid water environment.Three-dimensional measurement of the target structure.In order to verify the effectiveness of the proposed method,experimental tests were carried out in real scenarios.The accuracy measurement experiment of the distortion point cloud correction shows that using the Intel Real Sense SR300 depth camera can obtain effective point cloud image data within a range of 253 mm underwater.The 3D point cloud data after refraction distortion correction is used when measuring the 3D size of underwater structures.,Its measurement accuracy has reached ±3.77 mm,and the measurement error is 8.76%.Compared with the current mainstream measurement methods,the measurement accuracy of the method proposed in this paper is improved by 2.23 mm.The effect of turbidity on point cloud data collection experiments show that the "clean water-replacement" device can effectively eliminate the interference of environmental turbidity on point cloud data collection.The analysis of experimental results shows that the measurement accuracy of the method proposed in the study is relatively high,and the collection of point cloud image data is less affected by turbidity,and can be applied to complex water environment.