Experimental Study On Disintegration Characteristic Of Swelling Rock Subjected To The Dry And Wet Cycle

The disintegration of the swelling rock can lead to the exfoliation of the slope,the formation of caverns,the induction of collapse.And the provenances for landslides and mudslides are provided.So many geological disasters are caused.In the project,the swelling rock after disintegrating is often used as roadbed filler.But the disintegration of large particles has certain safety risks for the long-term stability of the roadbed.So in this paper,the swelling rock in Zhuzhou area of Hunan Province is taken as the research object.And the disintegration characteristic of swelling rock subjected to the dry and wet cycle is studied.And the results have good theoretical and practical significance for revealing the mechanism of disintegration and guiding engineering practice.The main research contents and conclusions are as follows:1.The mechanism of disintegration of swelling rock was studied.The tests of SEM,EDS,and XRD were carried out.Then the analytical methods of digital imaging systems,energy spectrum analysis,and software of Jade 6.0 were used.Afterwards the original void and structure,elemental content,and mineral composition of swelling rock were analyzed.After that the mechanism of disintegration of swelling rock was studied based on the above test.The results show that,the original void is relatively developed,the sample of No.1 has the complete grain structure,the sample of No.2 has the obvious sheet structure,and it has the characteristic of partial loose and directional arrangement.Furthermore,the mainly contain of swelling rock are the O,Mg,Al,Si,K,Ca,and Fe.And the mass fraction of O element exceeds 50%.Moreover,the mineral composition of the swelling rock mainly includes: quartz,calcite,feldspar,mica,kaolinite,chlorite,illite,nontronite,montmorillonite.And the quartz content which reaches more than 40% in both rock samples is the highest.what's more,swelling rock repeatedly undergoes the "water swelling and wedge fracture destruction coupled with water loss and dry cracking shrinkage" under the dry and wet cycle,resulting in the continuous disintegration of the expanded rock.2.The swelling and disintegration properties and their correlation of swelling rock were studied.The free swelling ration test,lateral constraint swelling stress,and lateral constraint swelling ration,and water-immersed disintegration test were carried out.The related indicators were used to quantitatively describe the characteristics of swelling and disintegration,and the relationship between different indicators and cycle times and the energy characteristics during disintegration were studied.Then based on the above test,the correlation between swelling and disintegration was studied.The results show that,slake durability index,standard basis entropy,disintegration ratio have good exponential correlation with cycle number,and fractal dimension has good logarithmic correlation with cycle number.Furthermore,the change law of newly added surface energy after disintegration can intuitively reflect the disintegration characteristics of the swelling rock.Moreover,swelling clay minerals are one of the major causes of disintegration of swelling rock.And the correlation between swelling and disintegration properties depends on the law of swelling.As the rock samples disintegrate and gradually break up,the law of the swelling and disintegration is basically the same as that of the swelling and the cycle number.3.There are many influencing factors of the disintegration of the swelling rock during the dry-wet cycle,the article focuses on the factors involved in the project.Using the water-immersion disintegration test,222 samples were prepared and 28 sets of tests were developed.That is,effects of different drying temperatures,external disturbances,different initial masses,dry and wet cycle effects,microstructures,and different indicators on disintegration are studied.The results show that,under static water immersion conditions,the drying temperature has a great influence on the disintegration properties.And relative to the drying temperatures of 105?,80? and 30?,the drying temperatures of 60? is the most favorable for the disintegration of the swelling rock.Then,in the case of external disturbance,the swelling rock can disintegrate rapidly,and the degree of disintegration is hardly affected by the drying temperature.Furthermore,compared with static water immersion,the disintegration rate of swelling rock under external disturbances is significantly faster than that under static submersion.However,when the cycle number is large,the disintegration rate of the expansive rock at the drying temperature of 60? can reach a level equivalent to that of the external disturbance.Moreover,the initial mass of the single block has a certain influence on the disintegration properties of the swelling rock,showing that the larger the mass of the bulk is,the faster the disintegration rate will be.what's more,the microstructure has a great influence on the disintegration of its particle size distribution.There are some subtle differences in the description of disintegration properties of swelling rock by using different indicators.Relative to the slake durability index,fractal dimension and disintegration ratio,the standard basic entropy is more suitable as an indicator for judging rock disintegration.