Papers by Author: Yong Zhang

Abstract: Considering the influence of atmosphere action, field test of swelling force on expansive soil is carried out in Nanning Guangxi. The test sustains a whole rain season. The testing results show that swelling force is closely linked to the process of rainfall. The phenomenon, that long drought turns the rain, induces a sudden change of swelling force. But the persistence of rainfall brings different influence on vertical and horizontal swelling force. The results of field test can provide reference to optimize the engineering design.

Abstract: Based on the consolidated undrained triaxial test of soft clay, a formula for computing pore water pressure is developed, by using of the critical state theory of volume strain and the characteristic normalization of soft clay. It is shown that the new proposed formula is reasonable to reveal the nonlinear stress-strain relationship and the dilatancy characteristics of soft clay. With the comparison between the pore water pressure simulation results by the new formula and the experimental data, it is shown that the simulation values agree well with the experimental data. Meanwhile, based on the failure criterion, a formula for the critical pore water pressure is proposed. It is shown that the new formula is reasonable to simulate the critical pore water pressure. It is very useful to predict the foundation stability.

Abstract: Through the undrained dynamic triaxial experiment, the deformation characteristics of saturated soft clay under cyclic loading are investigated. The cyclic loading was simplified as sine wave. It is found that under different dynamic stress, the deformation patterns of specimen in this experiment can be divided into three kinds, such as dense compressed, tensile break-up and shear failure type. In the process of vibration, the deformation forms of samples can also be divided into three types by dynamic stress amplitude, such as stable, destructive and critical type. The dynamic stress amplitude corresponding to the critical type is called critical dynamic stress. With the dynamic elastic strain increasing gradually, the dynamic elastic modulus decreases and rigidity softening occurs. Furthermore, dynamic elastic modulus and dynamic elastic strain curve decrease while the cyclic number is increasing. Finally, to establish the equation of the relationship between dynamic elastic modulus and dynamic elastic strain, the factor of cycle number should be considered.