Influence Of Water Environment On Engineering Properties And Mechanism Of Dispersive Clay

Repulsive force is greater than attractive force of intermolecular force between dispersive clay in deionized water(or pure water).Granular aggregate is made up of soil particles also can disperse into original level.There are huge security issues with the hydraulic structure built by dispersive clay because of the low resistance to erosion.The theory of soil mechanics shows that engineering properties of soil will be impacted by water environment,especilly for dispersive clay.In this research,dispersity identification tests(the pinhole test and crumb test),wet disintegration test,compression test,direct shear test and SEM test had been investigated in different concents of hydrochloric acid and sodium hydroxide,so as to study the effect on the dispersity,strength property and microstructure characteristics of dispersive clay with the change of water environment.Hoping to provide the basis of the management and safe operation of water conservancy projects.Research conclusions are as follows:(1)The pinhole test and crumb test showed that the dispering property of dispersive clay reduced with the increasig content of acid and alkaline.For the non-dispersive soil,the acid had no obvious effect on its dispersibility,while with the increasing content of the alkaline,its dispering property increased first,and than reduced.(2)The compression and direct shear test showed that the compression modulus,cohesion and internal frictional angle reduced of dispersive clay with the increasing content of acid while the compression modulus and cohesion climbed up and then declined with the increasing content of alkali,but the internal frictional angle changed irregular.(3)The SEM test showed that trellis pores and intergranular pores of dispersive clay increased with the increasing content of acid while the soil skeleton bacame dense and then loose with the increasing content of alkali.(4)The erosion mechanism of acid and alkali were different.The erosion mechanism of acid mainly included the corrosion of the cementing material in the soil and the ion exchange.The erosion mechanism of alkali mainly included the corrosion,precipitation cementation and the ion exchange.The engineering properties enhanced because of the precipitation cementation in a low content of alkali while reduced because of the corrosion in a high content of alkali.