Field Study of Downdrag and Dragload of Bored Piles in Consolidating Ground

AbstractThis paper reports a field study on the downdrag and dragload of two pairs of bored piles installed in consolidating ground in the Zhejiang coastal area, China. During and after the construction of a 2.5-m-high embankment, the dragload and downdrag induced on the four piles, surface and subsurface soil settlement, pore water pressure, and lateral earth pressure were monitored. The field measurements show that the maximum dragloads in piles founded on relatively stiffer (end-bearing pile) and relatively softer layers (floating pile) ranged from 1,198 to 1,238 kN and from 798 to 870 kN, respectively. This suggests that the dragload in a floating pile can be one-third less than that in an end-bearing pile with similar geometries and embedded in the same consolidating ground. Deduced β values above the neutral plane (NP) in the clay strata ranged from 0.28 to 0.3, respectively. A much smaller β (0.04–0.06) was found below the NP. The existing analytical solutions overestimated the depth of the NP, lea...

[1]  John Burland,et al.  SHAFT FRICTION OF PILES IN CLAY--A SIMPLE FUNDAMENTAL APPROACH , 1973 .

[2]  Harry G. Poulos,et al.  Effects of Tip Location and Shielding on Piles in Consolidating Ground , 2008 .

[3]  M. T. Davisson,et al.  Negative Skin Friction in Piles and Design Decisions , 1993 .

[4]  J. Little.  Downdrag on Piles: Review and Recent Experimentation , 1994 .

[5]  Barry Lehane,et al.  Behavior of Axially Loaded Pile Groups Driven in Clayey Silt , 2006 .

[6]  Bengt H. Fellenius,et al.  Determining the Resistance Distribution in Piles Part 1. Notes on Shift of No-Load Reading and Residual Load , 2002 .

[7]  T W Lambe,et al.  PREDICTION AND FIELD EVALUATION OF DOWNDRAG FORCES ON A SINGLE PILE , 1974 .

[8]  Jinchun Chai,et al.  Analysis of field performance of embankments on soft clay deposit with and without PVD-improvement , 2005 .

[9]  Yi Hong,et al.  Ground deformations and soil–structure interaction of a multi-propped excavation in Shanghai soft clays , 2012 .

[10]  Dian-Qing Li,et al.  Effect of spatially variable shear strength parameters with linearly increasing mean trend on reliability of infinite slopes , 2014 .

[11]  Gholamreza Mesri,et al.  The coefficient of earth pressure at rest , 1993 .

[12]  Leonardo Zeevaert.  Foundation engineering for difficult subsoil conditions , 1973 .

[13]  Malcolm D. Bolton,et al.  Numerical modelling of group effects on the distribution of dragloads in pile foundations , 2002 .

[14]  Yu Wang,et al.  Bayesian Model Comparison and Characterization of Undrained Shear Strength , 2014 .

[15]  Siew-Ann Tan,et al.  PERFORMANCE OF PRECAST DRIVEN PILES IN MARINE CLAY , 1991 .

[16]  L C Reese,et al.  DRILLED SHAFTS: CONSTRUCTION PROCEDURES AND DESIGN METHODS , 1999 .

[17]  Akira Asaoka,et al.  OBSERVATIONAL PROCEDURE OF SETTLEMENT PREDICTION , 1978 .

[18]  Buddhima Indraratna,et al.  Development of negative skin friction on driven piles in soft Bangkok clay , 1993 .

[19]  Lizhong Wang,et al.  Modeling Strain-Rate Dependent Behavior of KR0-Consolidated Soft Clays , 2012 .