Study on the surface morphology and fractal characteristics of granite under thermal shock of seawater

Geothermal energy has become one of the new energy sources of great concern due to its wide distribution, abundant reserves and green, clean and renewable advantages. In view of the advantages of both geothermal energy development potential and abundant seawater reserves in the coastal areas, granite is taken as the research object, and the surface topography under different temperatures (100 degrees C, 200 degrees C, 300 degrees C, 400 degrees C, and 500 degrees C) and different thermal shock cycles (0, 5, 10, 15 and 20) is obtained. Based on 3-D scanning technology, the damage details of the surface are reconstructed, and the roughness parameters of the surface are obtained. The maximum height, the maximum valley depth and the arithmetic mean height increase with the increase of the temperature and the number of times, but the maximum peak height does not change significantly. Based on fractal theory, the variation law of the fractal dimension is further discussed. The impact regions that affect the fractal dimension and thermal damage are divided: the weak impact region, the transition region, and the significant impact region. It lays a corresponding basic law for the heat exchange efficiency and strength charac-teristics of dry hot rock.