Vertical uplift resistance of two closely spaced horizontal strip anchors embedded in cohesive-frictional weightless medium

The vertical uplift resistance of two closely spaced horizontal strip plate anchors has been investigated by using lower and upper bound theorems of the limit analysis in combination with finite elements and linear optimization. The interference effect on uplift resistance of the two anchors is evaluated in terms of a nondimensional efficiency factor (eta(c)). The variation of eta(c) with changes in the clear spacing (S) between the two anchors has been established for different combinations of embedment ratio (H/B) and angle of internal friction of the soil (phi). An interference of the anchors leads to a continuous reduction in uplift resistance with a decrease in spacing between the anchors. The uplift resistance becomes a minimum when the two anchors are placed next to each other without any gap. The critical spacing (S-cr) between the two anchors required to eliminate the interference effect increases with an increase in the values of both H/B and phi. The value of S-cr was found to lie approximately in the range 0.65B-1.5B with H/B = 1 and 11B-14B with H/B = 7 for phi varying from 0 degrees to 30 degrees.

[1]  Jyant Kumar,et al.  Effect of Footing Roughness on Lower Bound Nγ Values , 2008 .

[2]  J. D. Geddes,et al.  Uplift of Anchor Plates in Sand , 1987 .

[3]  Scott W. Sloan,et al.  Stability of plate anchors in undrained clay , 2001 .

[4]  K. M. Kouzer,et al.  Vertical uplift capacity of a group of shallow horizontal anchors in sand , 2008 .

[5]  Malcolm D. Bolton,et al.  Vertical bearing capacity factors for circular and strip footings on Mohr–Coulomb soil , 1993 .

[6]  J. Kumar,et al.  Vertical uplift capacity of a group of two coaxial anchors in a general c-phi soil , 2012 .

[7]  K. M. Kouzer,et al.  Vertical uplift capacity of horizontal anchors using upper bound limit analysis and finite elements , 2008 .

[8]  Abdul-Hamid Soubra,et al.  Upper-Bound Solutions for Bearing Capacity of Foundations , 1999 .

[9]  Jyant Kumar,et al.  Effect of Footing Roughness on Bearing Capacity Factor Nγ , 2007 .

[10]  Jyant Kumar,et al.  Vertical uplift capacity of two interfering horizontal anchors in sand using an upper bound limit analysis , 2009 .

[11]  Robert Sparks,et al.  ANCHOR BEHAVIOR IN SAND , 1972 .

[12]  J. D. Geddes,et al.  Plate Anchor Groups Pulled Vertically in Sand , 1996 .

[13]  E. Davis,et al.  The behaviour of anchor plates in sand , 1982 .

[14]  Braja M. Das,et al.  MODEL TESTS FOR UPLIFT CAPACITY OF FOUNDATIONS IN CLAY , 1978 .

[15]  E. Davis,et al.  THE BEHAVIOUR OF ANCHOR PLATES IN CLAY , 1982 .

[16]  J. Pastor,et al.  Finite element method and limit analysis theory for soil mechanics problems , 1980 .

[17]  Wai-Fah Chen.  Limit Analysis and Soil Plasticity , 1975 .

[18]  G. G. Meyerhof,et al.  The Ultimate Uplift Capacity of Foundations , 1968 .

[19]  Scott W. Sloan,et al.  Lower bound limit analysis using finite elements and linear programming , 1988 .

[20]  S. Sloan,et al.  Upper bound limit analysis using discontinuous velocity fields , 1995 .

[21]  Radoslaw L. Michalowski,et al.  AN ESTIMATE OF THE INFLUENCE OF SOIL WEIGHT ON BEARING CAPACITY USING LIMIT ANALYSIS , 1997 .

[22]  R. Merifield,et al.  The ultimate pullout capacity of anchors in frictional soils , 2006 .

[23]  John R Booker,et al.  THE BEARING CAPACITY OF STRIP FOOTING FROM THE STANDPOINT OF PLASTICITY THEORY , 1971 .