STABILITY OF STRIP FOOTING ON SAND BED WITH CIRCULAR VOID

Abstract

Underground voids can be created by different reasons such as tunneling, mining, water and gas networks and old conduits. These voids can cause serious engineering problem leading to instability of the foundation, incurring severe damage to the superstructure. With population growth and resulting extension of urban sprawl to the areas of prior mining cavity such as new cities in Egypt (Menia new city, Assuit new city, Sohag new city and et.,) there is a growth STABILITY OF STRIP FOOTING ON SAND BED WITH CIRCULAR VOID concerning to the geotechnical engineering regarding the foundation stability in these areas. In this paper, numerical investigation of such phenomenon is presented using PLAXIS, 2D software. A series of numerical analysis for strip footing supported on sand bed with an inside circular continuous voids were carried out. The parameters studied in this investigation include the relative density of sand bed (dense sand, medium dense sand and loose sand), the voids embedment depth and voids diameter. The results demonstrate that the bearing capacity of strip footing decreases with the decrease of void embedment depth and vice versa. Also, the bearing capacity decreases with the increase of void diameter. For all sand relative densities, the undesirable structural effects of the void can be eliminated for a void embedded at a depth of around 3.5 times the void's diameter (D). An Equation relating the bearing capacity ratio with the influencing factors investigated is developed. This equation provides a data base useful for design of continuous footing centered with an underground void.