Study On Influencing Factors Of Uniaxialtensile Strength Of Dispersive Soil

Most or even all of the cohesion between clay in dispersive soil can disappear with theaction of deionized water or low salinity water. Granular aggregate is made up of soil particlesalso can disperse into original level. So it is easy to cause engineering accidents withoutprotective measures. So many researchers has researched on identification methods ofdispersibility, dispersion mechanism, application of dispersion improvement about dispersivesoil. These studies have helped people to know dispersive soil deeply, but researches aboutstrength characters of dispersive soil are rarely reported.Based on tensile strength characteristics of soil, we have developed uniaxial tensiletester and sample preparation mold. We have studied the law of dispersive soil along withtensile rate, aspect ratio, moisture content, compactness, clay content by using dynamicuniaxial tension tester. In this test, non-dispersive soil and transitional soil was used as acontrol to analyze fracture mechanism of dispersive soil.1)selfe-develoed instrument has offered a good method to study tensile strength, which issimple to use, and cost is low. The most appropriate stretching rate is0.8mm/min, and themost appropriate aspect ratio is2.5, adopting these indexes can avoid end effects and sampleweight.2) Uniaxial tensile strength of dispersive soil, transitional soil and non-dispersive soilwith the trends of moisture, compaction and clay content is basically same. The trend showsthat uniaxial tensile strength decreases with water content, on the contrary, uniaxial tensilestrength increases with compaction and clay content. Under the same test conditions uniaxialtensile strength of dispersive soil is the least, but uniaxial tensile strength of non-dispersivesoil is the largest, transitional soil is center.3) Tensile strength of dispersive soil is low compared with transitional soil andnon-dispersive soil, the main reasons are that the content of Na+is high and pH is high. The two reasons lead to diffuse double layer become thickness, then grivatation between soilpartical becomes lower, on the contrary repulsion becomes higher, uniaxial tensile strength ofdispersive soil reduces on the macro level. Fracture of the three kinds of soil is all brittilefracture. The tensile force in sample become zero immediately and there is no phenomenon ofwire diameter shrinkage.