Study On The Damage Characteristics Of Basalt Under Dry-wet Cycle In Chemical Condition

Water-rock interaction has always been an important factor affecting the stability of rock mass engineering,which has attracted the attention of many scholars.A large number of experimental studies have been carried out in recent decades.Long-term water-rock interaction will bring a series of problems,such as slope landslides,unstable dangerous rocks,bank slope instability,etc.,which will seriously affect the safety of people’s lives and property.In view of the above problems,in this paper,combined with the natural environment of Yunnan,the basalt of an open-pit mine slope in Yunnan was selected as the research object,and the HCl solution with pH=3.0,distilled water and NaOH solution with pH=11.0 were used as the soaking solution to carry out the dry-wet cycling test on basalt.The main research work and achievements are as follows:(1)Uniaxial compression tests were carried out on basalts at different stages under different chemical solutions and dry-wet cycles.Stress-strain curves were obtained at different stages of dry-wet cycles under different chemical solutions,and relevant mechanical parameters were calculated.On this basis,the variation of mechanical parameters with the number of wet-dry cycles and the relationship between the mechanical parameters of different chemical solutions under the same number of wet-dry cycles were analyzed.(2)The water absorption of basalt is tested and calculated.The results show that the water absorption of basalt in different chemical soaking liquids increases with the increase of wetting and drying cycles,but the water absorption of basalt in different pH values is different.It can be inferred that the dry-wet cycling test changed the fine pore characteristics of basalt and enhanced its water absorption.(3)Basalt after dry-wet cycling test was observed by scanning electron microscopy,and relevant data were consulted to prove that dry-wet cycling changed the micro-pore structure of basalt,and the change of pore structure of basalt was also different under different chemical solution conditions.(4)The concentration and pH value of the important ions in the soaking liquor during the dry-wet cycle test were measured,and the change rule with the increase of the number of dry-wet cycles was obtained.The dissolution rate of the ions was calculated,and the corrosioncharacteristics of the chemical solution to basalt were analyzed.On this basis,the chemical corrosion mechanism of feldspar in basalt in acidic,neutral and alkaline solutions was analyzed based on dissolution kinetics and X-ray diffraction analysis.(5)Assuming that the strength of basalts obeys Weibull distribution,based on the uniaxial compression deformation test results,the statistical constitutive model of rock damage under different chemical solutions and dry-wet cycles is constructed by using Lemaitre’s strain equivalence theory and continuous damage model theory.The results show that the calculated theoretical stress-strain curves are in good agreement with the experimental stress-strain curves.