Influence Factors of the Adhesion Strength of Clayey Soil

Abstract

AbstractWhen earth pressure balance (EPB) shield tunnels are constructed through clayey ground, the soil adheres to the cutter and cutterhead due to the high adhesion strength between the steel and the clay. To investigate the influence of different factors on the adhesion strength, this study used montmorillonite, kaolin and mixtures of the two as test soils. The adhesion strength between steel and clay was determined with a customized rotary shear apparatus. The results show that the adhesion strength between the steel and the clay increased with the consistency index. As the consistency index decreased, the effect of the normal pressure on the adhesion strength gradually weakened. As the contact angle of the shear plate increased, the adhesion strength decreased. The plasticity index had little effect on the adhesion strengths. The adhesion strength increased gradually with increasing surface roughness. The most important factors which influenced the adhesion strength are the soil consistency index, the normal pressure and the contact angle of the shear plate.KeywordsEPB shieldClayed soilAdhesion strength