Date of Award

Summer 2010

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil/Environmental Engineering

Committee Director

Isao Ishibashi

Committee Member

Duc T. Nguyen

Committee Member

Gene Hou


This study investigated the effect of anisotropy on passive pressure in sands by developing computer simulation utilizing FLAC code for plane strain condition. A series of wall movement modes was applied namely translation, rotation about a point below the wall, RBT, and rotation about a point above the wall, RTT.

From comparisons with other FLAC model in translation mode with isotropic material, the coefficients of passive pressure Kp were similar to each other except for some combinations of zero dilation, low wall friction, and high angle of internal friction ϕ. Dilation angle has less effect on Kp than the effect of ϕ. Dilation angle of a half of ϕ could be used without significant effects on Kp.

When comparing simulations with anisotropic material properties and model wall experiment in translation mode, the values of peak Kpx (Kp in x direction) from simulations were higher for loose sand, close for medium dense, and about the same for dense sand. Strains to reach the maximum Kpx were less for loose sand, close for medium sand, and higher for dense sand. In RBT modes, Kpx values were higher for low "n", and close for high "n" values", where "n" is the ratio of distance of center of rotation to the wall height. In RTT mode, Kpx values were higher from simulation with low "n", and close for high "n". For all modes, points of application of resultant of lateral earth pressure "a" at large wall displacement were practically similar. However, in the early stage of wall movement, there exist some differences.

From simulations with increasing "n" with various relative densities, Kpx values for RBT and RTT modes reached similar maximum at "n" about 2 and 15 respectively. For simulations with various ϕ angles in translation RBT (n=0), and RTT (n=0) modes, Kp values of anisotropic simulations were significantly smaller than the isotropic simulations. Increasing wall high from 0.5 m to 4.0 m resulted in lower Kpx values in anisotropic simulations with an average reduction of 13%.