Enhanced analysis of pile flexural behavior due to installation of adjacent pile

The installation of piles causes lateral soil movements which will induce additional lateral loading on adjacent existing piles. A simplified two-stage approach is conventionally adopted to quantify the installation effect on an adjacent pile. The first stage involves estimating the free-field lateral soil movement profile due to the pile installation process, and this is then applied as input to a pile–soil interaction analysis in the second stage. Such an approach is computationally efficient, but its efficacy has not been rigorously assessed due to the lack of reliable rigorous reference solutions. In this study, the Eulerian finite element approach is applied to obtain rigorous reference solutions for the response of an existing pile due to the installation of an adjacent pile. The efficacy of the two-stage approach is then evaluated against these reference solutions. It is found that the bending moment profiles generated using the simplified two-stage approach deviate significantly from the reference solutions. The shortcomings of the existing two-stage approach are identified, and an improved analysis method denoted as the Enhanced Multi-Stage Approach is proposed and validated in this paper. The results based on the Enhanced Multi-Stage Approach are found to be in good agreement with the more rigorous reference solutions.

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Thrust and bending moment of rigid piles subjected to moving soil

Canadian Geotechnical Journal ◽

10.1139/t09-092 ◽

2010 ◽

Vol 47 (2) ◽

pp. 180-196 ◽

Cited By ~ 39

Author(s):

Wei Dong Guo ◽

H. Y. Qin

Keyword(s):

Current Model ◽

Bending Moment ◽

Soil Movement ◽

Model Pile ◽

Experimental Apparatus ◽

Lateral Soil Movement ◽

Laterally Loaded ◽

The Given ◽

Maximum Thrust

An experimental apparatus was developed to investigate the behaviour of vertically loaded free-head piles in sand undergoing lateral soil movement (wf). A large number of tests have been conducted to date. Presented here are 14 typical model pile tests concerning two diameters, two vertical pile loading levels, and varying sliding depths with the movement wf driven by a triangular loading block. Results are provided for driving force as well as for induced shear force (T), bending moment (M), and deflection ( y) along the piles with wf / normalized sliding depth. The tests enable simple expressions to be proposed, drawn from the theory for a laterally loaded pile. The new expressions well capture the evolution of M, T, and y with soil movement observed in current model tests, and the three to five times difference in maximum bending moment (Mmax) from the two modes of loading. They further offer a good estimate of Mmax for eight in situ pile tests and one centrifuge test pile. The study quantifies the sliding resistance offered by a pile for the given wf profiles, pile location (relative to the boundary), and vertical load. It establishes the linear correlation between the maximum thrust (resistance T) and Mmax, regardless of the magnitudes of wf.

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Effect of consolidation on responses of a single pile subjected to lateral soil movement

Canadian Geotechnical Journal ◽

10.1139/cgj-2014-0157 ◽

2015 ◽

Vol 52 (6) ◽

pp. 769-782 ◽

Cited By ~ 14

Author(s):

L.Z. Wang ◽

K.X. Chen ◽

Y. Hong ◽

C.W.W. Ng

Keyword(s):

Soft Clay ◽

Bending Moment ◽

Coefficient Of Consolidation ◽

Construction Period ◽

Soil Movement ◽

Centrifuge Tests ◽

Short Period ◽

Lateral Soil Movement ◽

Pile Response ◽

Pile Length

Given extensive research carried out to study pile response subjected to lateral soil movement in clay, the effect of consolidation on the pile–soil interaction is rarely considered and systematically investigated. For this reason, four centrifuge tests were conducted to simulate construction of embankment adjacent to existing single piles in soft clay, considering two typical drainage conditions (i.e., drained and undrained conditions) and two typical pile lengths (i.e., relatively long pile and short pile). The centrifuge tests were then back-analyzed by three-dimensional coupled-consolidation finite element analyses. Based on reasonable agreements between the two, numerical parametric studies were conducted to systematically investigate and quantify the influence of construction rate and pile length on pile response. It is revealed that by varying drainage conditions, the piles respond distinctively. When the embankment is completed within a relatively short period (cvt/d2 < 2, where cv, t, and d denote the coefficient of consolidation, construction period, and pile diameter, respectively), the pile located adjacent to it deforms laterally away from the embankment. Induced lateral pile deflection (δ) and bending moment reduce with construction period. On the contrary, embankment constructed within a relatively long period (cvt/d2 > 200) leads the pile to deform laterally towards the embankment, with δ and bending moment increases with construction period. By halving the length of pile embedded in the drained ground, the maximum induced bending moment (BMmax) was slightly reduced (by 23%). On the other hand, shortening the length of the pile in the undrained ground is much more effective in reducing BMmax, i.e., halving pile length resulting in 78% reduction in bending moment. A new calculation chart, which takes various drainage conditions and pile lengths into account, was developed for estimation of BMmax.

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Offshore Permafrost Well Design Lateral Soil Movement-Induced Bending Strains

Journal of Energy Resources Technology ◽

10.1115/1.3231176 ◽

1985 ◽

Vol 107 (2) ◽

pp. 195-198

Author(s):

S. W. Laut ◽

M. T. Bradshaw

Keyword(s):

Free Field ◽

Permafrost Soil ◽

Soil Movement ◽

Offshore Production ◽

Field Displacement ◽

Well Design ◽

Production Wells ◽

Parametric Studies ◽

Lateral Soil Movement ◽

Soil Movements

Offshore production wells placed through permafrost are subjected to lateral soil forces when production of hot oil thaws the surrounding permafrost. Previous work completed indicates lateral soil movements in the Canadian Beaufort Sea to be large enough to cause severe bending strains in the well casing if the well casing moves with the soil. A lateral pile program was utilized to determine the bending strains induced in the well casing subjected to a free-field displacement of the thawed permafrost soil. Parametric studies were undertaken to determine the effect of varying soil properties and well casing rigidity for a given free-field displacement. The results show well casing strains to be lower than first predicted as the well casing does not move exactly with the soil.

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Behavior of Slender Piles Subject to Free-Field Lateral Soil Movement

Journal of Geotechnical and Geoenvironmental Engineering ◽

10.1061/(asce)1090-0241(2008)134:4(428) ◽

2008 ◽

Vol 134 (4) ◽

pp. 428-436 ◽

Cited By ~ 18

Author(s):

David J. White ◽

Mark J. Thompson ◽

Muhannad T. Suleiman ◽

Vernon R. Schaefer

Keyword(s):

Free Field ◽

Soil Movement ◽

Lateral Soil Movement

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Effect of Earthquake Induced Lateral Soil Movement On Pile Behavior

International Journal of Geotechnical Earthquake Engineering ◽

10.4018/jgee.2011070106 ◽

2011 ◽

Vol 2 (2) ◽

pp. 71-90

Author(s):

K. Muthukkumaran ◽

I.P. Subha

Keyword(s):

Seismic Analysis ◽

Ground Surface ◽

Bending Moment ◽

Bottom Layer ◽

Lateral Spreading ◽

Ground Failure ◽

Soil Movement ◽

Common Causes ◽

Margin Of Safety ◽

Lateral Soil Movement

One of the most common causes of ground failure during earthquakes is the liquefaction phenomenon, which produces severe damage to property. Although methods are available for seismic analysis of pile foundations, most of them consider soil to be an elastic material. Collapse of piled foundations in liquefiable areas has been observed in most recent strong earthquakes despite the fact that a large margin of safety is employed in their design. Lateral spreading of gently-sloping deposits of liquefiable sand is a cause of much damage in earthquakes, reportedly more than any other form of liquefaction-induced ground failure. The present investigation finds the effect of earthquake induced lateral soil movement on lateral pile capacity. Parametric study is carried out on the same model by changing the ground surface to different slopes on the top of the non liquefiable layer and by changing the length of the pile in the bottom layer of the non liquefiable layer. The paper focuses on the behaviour of pile under lateral soil movement due to earthquake. The bending moment and displacement behaviour of pile is studied in detail for different slope conditions.

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Pile response due to unsupported excavation-induced lateral soil movement

Canadian Geotechnical Journal ◽

10.1139/t96-091-312 ◽

1996 ◽

Vol 33 (4) ◽

pp. 670-677 ◽

Cited By ~ 19

Author(s):

H G Poulos ◽

L T Chen

Keyword(s):

Finite Element ◽

Boundary Element ◽

Bending Moment ◽

Major Effect ◽

Soil Movement ◽

Lateral Soil Movement ◽

Clay Layers ◽

Stage Analysis ◽

Pile Response ◽

Element Method

In this paper, a two-stage analysis involving the finite element method and the boundary element method is used to study pile response due to excavtion-induced lateral soil movements, focusing on unsupported excavations in clay layers. It is shown that the pile response in this case is different from that caused by excavations which are braced. Design charts for estimating pile bending moments and deflections are presented for free-head single piles, and these may be used in practice for assessing the behaviour of existing piles due to the excavation. However, proper account should be taken of the pile head condition, which has been found to have a major effect on the pile bending moment. The application of the charts is demonstrated via a study of a published case history. Comparisons are presented between measured pile behaviour and that predicted both from the chart solutions and the computer analyses, and reasonably good agreement is found between them. Key words: analysis, boundary element, excavation, finite element, pile, soil, movement.

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