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Pullout capacity of batter pile in sand

Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0, 10, 20, and 30. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pa occurs at batter angle approximately equal to 20, and it is about 21–31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18–75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted. | Journal of Advanced Research 2013 4 147-154 Cairo University Journal of Advanced Research ORIGINAL ARTICLE Pullout capacity of batter pile in sand Ashraf Nazir Ahmed Nasr Structural Engineering Department Faculty of Engineering Tanta University Tanta Egypt Received 25 December 2011 revised 22 March 2012 accepted 3 April 2012 Available online 7 May 2012 KEYWORDS Batter pile Pullout capacity Sand Inclination angle Pile roughness Shape of cross section Abstract Many offshore structures are subjected to overturning moments due to wind load wave pressure and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments these forces are due to earth pressure. For foundations in such structures usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose medium and dense sand to an embedded depth ratio L d vary from 7.5 to 30 and with various batter angles of 0 10 20 and 30 . Results indicate that the pullout capacity of a batter pile constructed in dense and or medium density sand increases with the increase of batter angle attains maximum value and then decreases the maximum value of Pa occurs at batter angle approximately equal to 20 and it is about 21-31 more than the vertical pile capacity while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is .