Enhancing the ability of the square footing to resist positive and negative eccentric-inclined loading using an inclined skirt

Abstract

Laboratory model tests were performed to investigate the behavior of shallow and inclined skirted foundations placed on sandy soil with R.D%=30 and the extent of the impact of the positive and negative eccentric-inclined loading effect on them. To achieve the experimental tests it was used a box of (600*600)mm cross-sectional and 600mm in height and a square footing of (50*50)mm and 10mm in thickness attached to the skirt with Ds=0.5B and various an angle of (10°,20°,30°). The results showed that using skirts leads to a significant improvement in load-carrying capacity and decreased settlement in addition when the skirt angle increased, the ultimate load improved. load-carrying capacity decreased with increasing eccentricity and load inclination For load inclination (Beta) 15° when the eccentricity changed from e=0.15B to e=0.05B the load improvement percentages were (323.2% to 263%) and (214% to 220%) and settlement reduction factor was (83% to 78%) and (62% to 58%) for positive and negative eccentric-inclined loading, respectively also the result showed the effect of positive on the reduction of soil-bearing capacity is more than negative. Increasing eccentricity increases the improvement percentage for positive eccentric-inclined load and decreases for the case of negative eccentric-inclined load. Increased skirt angle will increase the Improvement factor (IR) When the skirt angle increased from 10° to 30° for an improved foundation with load angles of 5°, 10°, and 15° the improvement factor (IR) increased from (2.53, 2.51, 2.4) to (3.45, 3.65, 3.97) and (2.43, 2.58, 2.54) to (4, 4.63, 5.3) for both negative and positive eccentric-inclined load respectively and settlement reduction factor for load angle 15° and skirt angle increase from 10° to 30° were 34% and 27% for positive and negative eccentric-inclined load respectively. the (IR) for positive eccentric-inclined load is more than the negative eccentric-inclined load for all cases, in addition, the skirt angle of 30° showed a significant improvement in the improvement factor (IR).