Influence And Analysis Of Limestone Strength Under Water-rock Physics And Chemistr

As engineering materials widely existing in nature and widely used in engineering,rock structure is not only complicated due to the existence of a certain amount of internal pores,fracture surface and corresponding joints.However,these defects will cause the mechanical performance of rocks to change with the change of external environment,and water,as one of the above external environments,is regarded as a non-negligible stability of geotechnical engineering.In view of the complex temporal and spatial evolution mechanism of limestone damage and the lack of rapid identification theory for the safety assessment of engineering construction foundation in the region with different damage degrees of limestone,different acidic environments were used for soaking treatment,that is,dilute hydrochloric acid solution with p H=3,p H=5 and PH-7 were soaked.The mechanical behavior and strength deterioration of limestone soaked in acid solution at different acidity levels were investigated.The main research contents and achievements are as follows:(1)The corresponding performance of physical parameters of limestone soaked in acid solution is studied.In the limited soaking space and relatively closed environment,the physical deterioration property of limestone under acidic solution is time-dependent,that is,in the early stage of soaking,the acidic solution is mainly in contact with the outer wall of limestone specimen,thus producing chemical reactions to neutralize acidic substances.In the middle stage of soaking,the acid solution mainly invaded the interior of the rock,which was mainly represented by the slow increase of calcium and magnesium ions.At the later stage of soaking,the acid substance is exhausted,and the main corrosion is water.The increase of physical deterioration parameters in acidic solution was mainly concentrated in the early stage and the late stage of soaking,that is,the period when acidic substances were effective.(2)The mechanical strength characteristics of limestone specimens with different damage degrees were studied.Uniaxial compression test was carried out to study the corresponding strength deterioration of limestone specimen under the corrosion of acid solution,and the variation law of corresponding strength parameters was obtained.In the relevant enclosed environment,the uniaxial compressive strength of limestone decreases slowly with the increase of soaking days,and finally becomes stable.In this paper,the fitting formula of limestone strength and soaking days is obtained by statistics of deterioration data of corresponding days.On this basis,the days when different soaking environments reach a stable state and the corresponding strength of rock specimens at that time are estimated.(3)The energy characteristics of limestone specimens with different damage degrees were studied.Through uniaxial compression test,the stress-strain curves under corresponding conditions are obtained.Based on this,the strain energy values of rocks under different deterioration degrees are obtained through calculation and analysis.According to the statistics and analysis of the corresponding soaking environment,the variation law of strain energy in different soaking environment was obtained.The rule shows that:in the effective stage of acidic substances,acidic substances and aqueous solutions change the strain limit value by changing the elastic modulus,so that the strain energy increases first and then decreases,and finally presents a slow decline trend.(4)Explore the reasons for the differences in energy characteristics of different limestone samples.Through the above calculation of strain energy,the energy change coefficient is defined and the energy change coefficient in the elastic body in the ideal case is determined.By calculating the energy change coefficient of limestone specimens in different soaking environments and soaking days,it is determined that the energy change coefficient is usually greater than 1.5625 during the effective period of acidic substances.At the acid depletion stage,the energy change coefficient is usually less than 1.5625,and the elastic-plastic stability is relatively high.