Experimental Study On Water Chemical Environment Effect On The Fracture Toughness Of Sandstone

The rock is a natural and complex material in nature. It is a collection of particles or crystals by mutually cemented together, which is different from the general engineering materials. Because of its special diagenetic process, the initial micro cracks and defects exist in the rock inevitably. However, the rock is often in water environment,with the rapid development of the national industry, soil water, groundwater, rivers and lakes are polluted in different degrees, so that the water shows the different p H.Therefore, the mechanical properties of rock are affected by the water solution, which leads to erosion of rock through initial micro cracks and defects, then the rock tensile strength, compressive strength and fracture toughness and other mechanical parameters are affected by the complex water environment.In this paper, the purpose of the experiment is to test a study on chemical damage of sandstone fracture toughness, with the changes of the solution p H, relative quality,porosity and the fracture toughness of the specimens, the deterioration mechanism of sandstone fracture toughness was studied in the macro opinion. I respectively from the macro solution p H changes, relative quality and porosity of the specimens, and the fracture toughness specimen changes with time and p H value, study of sandstone fracture toughness deterioration mechanism. Through the test and analysis of the test results, the following results were got in this paper:① When sandstone were immersed in the water chemistry solution, Water-Rock Interaction would be changed with time going, meanwhile, the solution p H, relative quality and porosity of sandstone would be changed in relation to Water-Rock Interaction.② When sandstone were immersed in the water chemistry solution, then the fracture toughness of sandstone lower than the un-immersed, It is showing that the fracture toughness of sandstone was damaged, And with the immersed duration going,the fracture toughness was reduced; With the soaking solution p H decreasing, the fracture toughness was reduced.③the un-immersed sandstone were compared with the immersed,It was found that the failure processes were different. The lower of failure loading was loaded on sandstone, the earlier cracks appeared, the compaction process and the failure duration was longer, then rock ductility was showed, which was different from the whole brittlefailure in initial state.④Sandstone fracture toughness has obvious size effect, the size larger, the value higher.⑤ The deterioration mechanism of sandstone fracture toughness was analyzed,made calculation of damage variable and found the regularity of fracture damage, in view of two factors such as duration and PH respectively.