Behaviour of Shallow Strip Foundation on Granular Soil Under Eccentrically Lnclined Load

Abstract

Since the publication of Terzaghi’s theory on the ultimate bearing capacity of shallow foundations in 1943, results of numerous studies—both theoretical and experimental—by
various investigators have been published. Most of the studies relate to the case of a vertical load applied centrally to the foundation. Meyerhof (1953) developed empirical procedures for estimating the ultimate bearing capacity of foundations subjected to eccentric and inclined loads. Based on the review of the existing literature on the bearing capacity of shallow foundations, it appears that limited attention has been paid to estimate the ultimate bearing capacity when the foundation is subjected to both eccentric and inclined load and the objective of present study stems from this paucity. Besides, only a few studies have been made to estimate the average settlement of embedded footings when subjected to eccentric load.In order to arrive at the objective and to quantify certain parameters, extensive laboratory model tests have been conducted to determine the ultimate bearing capacity of shallow strip foundation resting over sand bed and subjected to eccentric and inclined loads. The tests have been conducted on two types of sand i.e. dense sand and medium dense sand.
The load inclination has been varied from 00 to 200 whereas the eccentricity varies from 0 to 0.15B (B = width of footing). Depth of the footing is varied from 0 to B. Traditionally,in all analysis of such problems; the line of load application is towards the center line of the footing. However, in this thesis, it is investigated for the two possible ways of load application i.e. (i) towards and (ii) away from the center line of the footing.Based on the model test results, an empirical non-dimensional reduction factor has been developed for each mode of load application. This reduction factor will compute the ultimate bearing capacity of footing subjected to eccentric and inclined load by knowing the ultimate bearing capacity of footings under centric vertical load at the same depth of footing. Similarly, neural network models have been developed under each mode of load application and combined mode of load application to compute reduction factor as described above. Finally, the developed equations are compared with the existing theories.vi In addition to bearing capacity, the settlement of eccentrically loaded embedded footings is investigated. Based on some of those laboratory test results as discussed above, an empirical procedure has been developed to estimate the average settlement of the foundation subjected to an average allowable eccentric load per unit area, where the applied load is vertical.