Study on Three-dimensional Bearing Capacity on Level and Slope Grounds

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In order to study three-demensional properties of failure surface and of the ultimate bearing capacity (qu), when loaded on bases in finite length placed on level and slope foudations, and to propose a practically useful design method of stability analysis, laboratory loading tests were performed on sand and clay foundations by changing the ratio of base size (eta=B/L) and the position of the base on the foundation.In loading test on level ground, qu-value decreases as eta increases in sand foundations, showing shape factor (s=q_3/q_2=1+neta) of n=-0.2 - -0.5 that is in good agrreement with other test results as pbtained. In clay foundations on the other hand, qu-value increases as eta increases in the similar manner as analytical results, nevertheless n-value showed a considerably large defference.In loading tests on sand slope, qu-value increase as eta increases unlike in level grounds, but the trend of qu showed gradual change to level ground as the distance from the slope shoulder increases. In comparisons with computation, test results of qu were in good correspondence in the range eta<0.5, but showed considerably smaller value as eta approaches to unity (square foundation).In loading tests on sands, failure surfaces were obseved successfully by setting thin dark stripes between sand layrs, and they were to be approximated mathmatically in good accuracy with log-spiral curves.The three-dimensional slice method of analysis of bearing capacity which has already been proposed for level ground was extended to problems of sloping ground, of inclined anisotropic ground, and of eccentric and inclined loading conditions. Quite successful results were obtained by comparing the above test results and solutions so far presented.