scholarly journals Numerical analysis of negative skin friction on piles in soft clay

HBRC Journal ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Yasser M. El-Mossallamy ◽  
Ashraf M. Hefny ◽  
Magdy A. Demerdash ◽  
Mohamed S. Morsy
Keyword(s):  
Numerical Analysis ◽  
Skin Friction ◽  
Soft Clay ◽  
Negative Skin Friction

Drag load on end-bearing piles in collapsible soil due to inundation

2016 ◽  
Vol 53 (12) ◽  
pp. 2030-2038 ◽  
Author(s):  
Ibrahim Mashhour ◽  
Adel Hanna
Keyword(s):  
Experimental Investigation ◽  
Skin Friction ◽  
Soft Clay ◽  
Soil Layer ◽  
Design Procedure ◽  
Collapsible Soil ◽  
Negative Skin Friction ◽  
Collapsible Soils ◽  
Surrounding Soil ◽  
End Bearing Pile

Collapsible soils may experience sudden and excessive settlement when inundated. The use of pile foundations that penetrate the collapsible soil layer to reach a firm stratum is widely used in practice. However, when the ground is inundated, large and sudden settlement of the surrounding soil may take place, causing negative skin friction on the pile’s shaft, which may lead to catastrophic failure. In the literature, research dealing with negative skin friction for piles in collapsible soil is lagging due to the complexity of modeling collapsible soil analytically. Alternatively, results of sophisticated experimental investigation may produce valuable information to predict the negative skin friction and accordingly the drag load on these piles. This paper presents the results of an experimental investigation on a single end-bearing pile in collapsible soil. The investigation is tailored to measure the soil collapse before and during inundation and the associated drag load on the pile. The theory proposed by Hanna and Sharif in 2006 for predicting negative skin friction on piles due to consolidation of the surrounding soft clay was extended to predict the negative skin friction for these piles in collapsible soils. A proposed design procedure is presented.

Numerical Analysis of Negative Skin Friction for Pile under Surface Loading by Particle Flow Code

2012 ◽  
Vol 166-169 ◽  
pp. 482-486
Author(s):  
Feng Xi Zhou ◽  
Yuan Ming Lai
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Skin Friction ◽  
Two Dimensions ◽  
Particle Flow ◽  
Particle Flow Code ◽  
Surface Loading ◽  
Negative Skin Friction ◽  
Pile Interaction ◽  
End Bearing Pile

Numerical simulations of soil-pile interaction under surface loading are performed by particle flow code in two dimensions. Considering an end-bearing pile subjected to flexible distribution load, the variety of negative skin friction is studied. Numerical results show that negative skin friction is variation with the increasing of surface loading, and the negative skin friction is decrease when the value is up to ultimate skin friction.

Development of negative skin friction on driven piles in soft Bangkok clay

1992 ◽  
Vol 29 (3) ◽  
pp. 393-404 ◽  
Author(s):  
B. Indraratna ◽  
A. S. Balasubramaniam ◽  
P. Phamvan ◽  
Y. K. Wong
Keyword(s):  
Skin Friction ◽  
Prestressed Concrete ◽  
Load Transfer ◽  
Soft Clay ◽  
Driven Piles ◽  
Short Term ◽  
Negative Skin Friction ◽  
Pullout Tests ◽  
Pore Pressures

This paper describes the results of short-term pullout tests and long-term full-scale measurements of negative skin friction on driven piles in Bangkok subsoils. Two instrumented cylindrical (hollow) prestressed concrete piles were fully equipped with two independent load-measurement systems, load cells, and telltale rods. Pore pressures and ground movements in the vicinity of the piles were monitored throughout the period of investigation. The effect of bitumen coating on negative skin friction was also studied. The long-term behaviour of driven piles was compared with the estimated values obtained from short-term pullout tests and soil strength data. It was found that the negative skin friction can be predicted well by the effective stress approach using values of β between 0.1 and 0.2. The load–settlement and load–transfer behaviour were numerically modelled to acquire a more comprehensive understanding of negative skin friction developed on driven piles. A settlement-controlled concept is also introduced for piles subjected to negative skin friction, on the basis of these findings. Key words : consolidation, downdrag, driven pile, embankment, finite elements, pore pressures, pullout, settlements, soft clay.

Down-drag on Piles in Clay due to Negative Skin Friction

1972 ◽  
Vol 9 (4) ◽  
pp. 323-337 ◽  
Author(s):  
Bengt H. Fellenius
Keyword(s):  
Skin Friction ◽  
Soft Clay ◽  
Clay Layer ◽  
Bending Moments ◽  
Pile Head ◽  
Design Rules ◽  
Negative Skin Friction ◽  
Negative Friction ◽  
One Year ◽  
Regional Settlement

In Part I of this report the results are given from 43 months of measurements of forces and bending moments on two instrumented precast piles driven through 40 m (130 ft) of soft clay and 15 m (50 ft) into underlying silt and sand. The force in the piles increased due to negative skin friction. After the first 5 months a force of nearly 40 tons was observed at the bottom of the clay layer. During this time the reconsolidation of the clay after the driving took place. The force due to the reconsolidation effect amounted to about 30 tons, while the rest was due mainly to negative skin friction caused by a small regional settlement. The latter force increased linearly with time by about 15 tons per year. Seventeen months after the driving the pile heads were loaded with 44 tons and one year later another 36 tons were added. The load on the pile head eliminated the negative skin friction, which however started to return with the continued regional settlements.In Part II of the report general design formulae for piles considering negative skin friction are given. The formulae should be used to check that the permanent and transient working loads, which have been chosen according to ordinary design rules, are not too large when negative skin friction develops.When settlements due to negative skin friction are not acceptable, the negative friction can be reduced by applying a thin coat of bitumen to the piles. References are made to investigations concerning reduction of skin friction, and practical difficulties are pointed out.

3D numerical analysis of piled raft interaction in drained soft clay conditions

2021 ◽  
Vol 14 (5) ◽  
Author(s):  
Abdelkrim Ferchat ◽  
Sadok Benmebarek ◽  
Mohamed Nabil Houhou
Keyword(s):  
Numerical Analysis ◽  
Soft Clay ◽  
Piled Raft

scholarly journals Downdrag Measurements on a 160-Ft Floating Pipe Test Pile in Marine Clay

1972 ◽  
Vol 9 (2) ◽  
pp. 127-136 ◽  
Author(s):  
M. Bozozuk
Keyword(s):  
Skin Friction ◽  
Compressive Load ◽  
Marine Clay ◽  
Positive Skin ◽  
Negative Skin Friction ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Test Pile ◽  
Excess Pore

Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about [Formula: see text] (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end where the positive excess pore pressures were high and relative movement between the pile and the soil was large, the positive skin friction approached the remoulded strength as measured with the field vane. Skin friction was increasing, however, as positive escess pore pressures dissipated.This paper shows that skin friction loads are related to the combination of (a) in situ horizontal effective stresses, (b) horizontal stresses due to embankment loads, and (c) horizontal stresses due to differential settlement of the fill.

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