Effect of Flexible Void on Ultimate Bearing Capacity of Eccentrically Loaded Shallow Strip Footing on Granular Soil

Abstract

Since the development of Terzaghi's theory on the ultimate bearing capacity of shallow foundations in 1943, outcomes of various studies either theoretical, experimental and numerical, done by various investigators has been brought into light. Apart from centric vertical load, various researchers have also studied the effect of eccentric vertical load, centric inclined load and eccentrically inclined load on foundation system. Due to chemical flow, underground pipe lines, mining, blasting and other underground activities, which have dynamic impact on the soil creates flexible voids below the foundation. Nearness of void underneath the footing influences the stability itself and causes serious harm to the structure.
Based on the literature review, it appears that limited research has been carried out in the field of ultimate bearing capacity of shallow foundation, when the foundation is subjected to eccentric vertical load having a void beneath the foundation. The origin of present study targets that scarcity in research.
In order to achieve the objective, one hundred and fifty-six numbers of numerical models have been made using PLAXIS to study the ultimate bearing capacity of shallow strip foundation resting over dry sand bed with the flexible void underneath the footing. The embedment ratio (Df /B) was varied from zero to one. The eccentricity was varied from 0 to 0.15B (where, B = width of footing) with an increment of 0.05B. The effect of flexible void on the ultimate bearing capacity of the footing has been analyzed by varying the size (D = Diameter of void), location (L = Location of void below foundation base) and horizontal distance (H) of the voids from center line of the footing. Based on the numerical results, three numbers of reduction factors are developed to predict the ultimate bearing capacity of shallow strip footing lying over a void on dry sand bed by knowing the ultimate bearing capacity of footing in the absence of flexible void.