Three-Dimensional Reconstruction Of Porous Structure Of Pervious Concrete Based On Simulated Annealing Algorithm

Permeable concrete is essential for the construction of sponge cities.And the permeability of permeable concrete is closely related to its pore structure.Since the previous qualitative research projects are usually conducted for the pore structure model through physical experiments,it is impossible to quantitatively describe the characteristics of pore distribution.Therefore,establishing a real model of the pore structure and quantitatively describing the characteristics of the pore structure has been widely concerned.In this thesis,the 3D numerical reconstruction of the pore structure of permeable concrete is explored,and the following research work are implemented:（1）Continuous slice images of permeable concrete were obtained through CT scanning.Optimization measures such as clipping,gray scale adjustment,filtering and threshold segmentation were conducted for these slice images by means of Avizo software.Moreover,the3D structural model of permeable concrete was reconstructed through volume rendering,and the visualization of the 3D structure was achieved.Through research,it is found that the size,geometry and distribution of pores in the model are consistent with the original model.It has the original pore structure characteristics.（2）Based on Tianhe-2 Supercomputer,the seepage simulation of the FCC array model was conducted through the Lattice Boltzmann（LBM）method,and the simulation results were compared with the theoretical values.It is found that the error is only 5%.Furthermore,standard samples generated from PFC were produced by 3D printing technology.The seepage experiments were carried out with standard samples.The research is conducted by means of experiments and numerical simulation,thus verifying the accuracy of the LBM method.（3）Focusing on the problems in 3D reconstruction based on simulated annealing,clustering segmentation solutions were provided to appropriately solve the excessive isolated pores and isolated matrices in pores.Based on the improved simulated annealing algorithm,the autocorrelation function and linear path function were adopted for the reconstruction calculation of reference models with different resolutions.Methods of recurrence rate and permeability were proposed to evaluate the effectiveness of 2D and 3D reconstruction models.The results show that the reconstruction based on the autocorrelation function is characterized by better effectiveness.As for the 3D reconstruction of models with a resolution of about 100,if the maximum lag length R is 45,and annealing coefficientsλ_minandλ_max are 0.2 and 0.75,respectively,the permeability error will only be 2.29%.Therefore,the optimal effectiveness and efficiency of reconstruction will be achieved.（4）Based on Avizo software,the pore network models were extracted from the reconstruction and reference models.Statistical analysis was conducted for the parameters in the pore network models.It is found that the pore distribution and connectivity of the reference model are highly like those of the reconstruction model,thus also verifying the effectiveness of the reconstruction algorithm.