Koichi Isobe

Ultimate Lateral Resistance of Pile Group in Clayey Soils Against Various Directions of Ground Movement

This study estimated the ultimate lateral resistance of pile group against horizontal ground movement by using two-dimensional rigid plastic finite element method (RPFEM). The effect of ground movement direction on the ultimate lateral resistance was investigated through the case studies. According to the results, it can be seen that changes in both the ultimate lateral resistance and the failure mode of ground around piles were observed. The effect of the pile spacing on load apportionment ratios was studiously investigated. Since each pile in the group affects other piles, it leads the load apportionment ratio significantly to depend on pile positions such as the front or back piles. Moreover, the load apportionment ratio of each pile went up with an increase in pile spacing, but it was obtained different remarkably among piles. The load apportionment ratio varied with the direction of the ground movement.

ULTIMATE BEARING CAPACITY ANALYSIS OF GROUND AGAINST INCLINED LOAD BY TAKING ACCOUNT OF NONLINEAR PROPERTY OF SHEAR STRENGTH

In the assessment of bearing capacity of footing, the bearing capacity formula proposed by The Architectural Institute of Japan (AIJ) has been widely used in Japan for the design of building foundation. However, this formula is limited to simple conditions like simple footing shape, flat ground and uniform material property. Although the rigid plastic finite element method (RPFEM) can solve this complex problem, it has not taken into account the size effect in assessment of bearing capacity. This study newly develops the RPFEM by introducing the nonlinear shear strength property against the confining stress and proposes the rigid plastic constitutive equation of parabolic yield function, basing on the change in the angle of shear resistance of Toyoura sand. The developed method and the bearing capacity formula (established by empirical approach) provided identical results for various footing sizes showing good estimation for wider range of footing size.