Foundation will be subjected to resistance during the process of uplift or pullout. Adhesion is a contributing component of the resistance and a key factor in determining the pullout capacity of soils. In order to study the laws and factors of adhesion

the compound adhesion-measuring disc is modified to eliminate the effect of the pore water pressure of soils on adhesion during its pullout by venting the bottom of the inner disc. Adhesions of soil are measured with different water contents and pullout velocities. Test results show that the drawing stress of soil on structure increases linearly with the increase of the displacement of pullout until it reaches adhesion limit. The adhesion of soil is zero when the water content is low and increases when the water content exceeds plastic limit. It decreases to a constant value after it reaches its maximum. The maximal cohesion under constant pullout velocity increases and the corresponding water content decreases as the pullout velocity increases. When the water content of soil is the same

the relationship between adhesion and the logarithm of pullout velocity is in an S shape. The ratio of adhesion to undrained shear strength increases with the increase of water content. The test results provide a sound basis for understanding the laws of adhesion and can be used in practical engineering.