Effect of stress level on the bearing capacity factor, N γ , by the ZEL method

Abstract

It has been known that soil shear strength parameters are stress level dependent. On the other hand, foundation size has a significant effect on the level of imposed stress on subsoil elements. In this study, the Zero Extension Lines (ZEL) method, which has wide applications in determination of bearing capacity and load-displacement behavior of foundations and retaining walls, is employed to consider the stress level dependent nature of soil shear strength parameters to predict the actual bearing capacity of foundations. The ZEL equations which are capable of considering variations in soil shear strength parameters have been employed to consider their dependency on stress level and solved numerically by a computer code developed for this study. The presented approach has been compared with experimental data showing reasonable predictions when the effect of stress level is taken into account. It is then utilized to develop some design charts showing modified values of N γ , as a function of foundation size and soil properties based on Bolton (1986) equation for stress level effect in cases of smooth and rough base foundations. The charts represent the decreasing tendency in N γ with an increase in foundation size and it shows the decreasing tendency in the reduction rate when the foundation size increases.

End-bearing capacity of driven piles in sand using the stress characteristics method: analysis and implementation

“…As the variation of soil friction angle has a major influence on N q , it becomes important to examine the dependency of soil friction angle on the stress level. The dependency of soil friction angle on the stress level has been well observed and reported (Meyerhof 1950;Bolton 1986), and its influence on the bearing capacity of shallow foundations has been widely studied (Bolton and Lau 1989;Clark 1998;Jahanandish et al 2010). In deep foundations, this effect seems to be of greater importance.…”

“…The bearing capacity, N g , decreases with an increase in the width and (or) diameter of the foundation. This aspect has been thoroughly investigated in the available literature for shallow foundations (Bolton andLau 1989, 1993;Clark 1998;Cerato 2005;Cerato and Lutenegger 2007;Yamamoto et al 2009;Jahanandish et al 2010;Veiskarami et al 2011).…”

“…In summary, the superposition assumption can be dropped, at least for cases in which both the surcharge and self-weight effects are important. In shallow foundations, the contribution of the surcharge pressure is negligible, in particular for relatively large foundations and, hence, the role of the third bearing capacity factor, N g , is much more important (Jahanandish et al 2010). In contrast, for deep foundations, the surcharge and the self-weight effects are of similar importance.…”

Stability of Supported Vertical Cuts in Granular Matters in Presence of the Seepage Flow by a Semi-Analytical Approach

“…The literature review behind the stability analysis for problems addressed above is rather long and rich with contributions including the force limit equilibrium methods (classically Coulomb [1,[4][5][6][7][8][9][10], method of stress characteristics (Sokolovskii, 1965;Larkin, 1968;Ghahramani, 1972 and1973;Houlsby and Wroth, 1982;Kumar, 2001; Kumar and Chitikela, 2002) [11][12][13][14][15][16][17] or the limit analysis (Chen, 1969;Lysmer, 1970;Chen and Davidson, 1973;Collins, 1973;Chen, 1975 [18][19][20][21][22][23][24][25][26][27][28], among others. Attempts to include the e ect of the groundwater ow in the stability analysis may date back to Terzaghi (1943) who studied the stability of the soil mass in the vicinity of sheet pile walls [3].…”

Evaluation of Load Bearing Capacity of Foundations with Different Vertical Cross-sectional Shapes

“…Moststudies on the interaction of foundations with soil bases are carried out using load-settlement approach. Many studies [14][15][16][17][18], havebeen conducted on the effect of foundation shape on settlement and load bearing capacity of soils.Vast of these past studies considered the shape of the foundations plan-wise. The interaction of these shapes of foundations with the soil bases is such that the soil above their bases contributes to the resistance of the structural loads mostly by surcharging the soil below the base of the foundation.Therefore the study of other shallow foundations shapes, which can both partly distribute/resist structural loads vertically along their trunks and bases, is presented.…”