Effect of Earthquake Induced Lateral Soil Movement On Pile Behavior

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.

scholarly journals Thrust and bending moment of rigid piles subjected to moving soil

2010 ◽  
Vol 47 (2) ◽  
pp. 180-196 ◽  
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.

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

2015 ◽  
Vol 52 (6) ◽  
pp. 769-782 ◽  
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.

scholarly journals Fragility functions for performance-based ground failure due to soil liquefaction

2017 ◽  
Author(s):  
Brett Maurer
Keyword(s):  
Land Use Planning ◽  
Ground Surface ◽  
Lateral Spreading ◽  
Soil Liquefaction ◽  
Hazard Mapping ◽  
Fragility Functions ◽  
Damage Potential ◽  
Damage State ◽  
Site Assessment ◽  
Ground Failure

The severity of liquefaction manifested at the ground surface is a pragmatic proxy of damage potential for various infrastructure assets, making it particularly useful for hazard mapping, land-use planning, and preliminary site-assessment. Towards this end, the recent Canterbury, New Zealand, earthquakes, in conjunction with others, have resulted in liquefaction case-history data of unprecedented quantity and quality, presenting a unique opportunity to rigorously develop fragility-functions for liquefaction-induced ground failure. Accordingly, this study analyzes nearly 10,000 liquefaction case studies from 23 global earthquakes to develop fragility functions for use in performance-based frameworks. The proposed functions express the probability of exceeding specific severities of liquefaction surface manifestation as a function of three different liquefaction damage measures (LDMs), wherein four alternative liquefaction-triggering models are used. These functions have the same functional form, such that end-users can easily select the model coefficients for the particular damage state, triggering model, and LDM of their choosing.It should be noted that these functions are not to be used to predict lateral spreading, which requires LDMs other than those assessed herein. Lastly, the proposed functions are preliminary and subject to further development. In this regard, several thrusts of ongoing investigation are discussed.

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

2014 ◽  
Vol 51 (6) ◽  
pp. 705-711 ◽  
Author(s):  
Kee Kiat Tho ◽  
Zongrui Chen ◽  
Chun Fai Leung ◽  
Yean Khow Chow
Keyword(s):  
Interaction Analysis ◽  
Free Field ◽  
Bending Moment ◽  
Flexural Behavior ◽  
Computationally Efficient ◽  
Two Stage ◽  
Soil Movement ◽  
Multi Stage ◽  
Element Approach ◽  
Lateral Soil Movement

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.

Response amplification of back-rotated piles

2020 ◽  
Vol 57 (11) ◽  
pp. 1780-1795 ◽  
Author(s):  
Wei Dong Guo
Keyword(s):  
Failure Mechanism ◽  
Shear Force ◽  
Bending Moment ◽  
Lateral Spreading ◽  
Model Tests ◽  
Integral Abutment ◽  
Rotational Stiffness ◽  
Soil Movement ◽  
Response Amplification ◽  
First Time

Piles are largely back-rotated in sliding slope or subjected to lateral spreading. This paper reveals for the first time that response of these piles (e.g., displacement, rotation, bending moment, and shear force) is amplified against forward rotating piles. In particular, magnification is detrimental, once normalized rotational stiffness (NRS) of the piles is around a singularity value (i.e., normalized singularity stiffness, NSS). New expressions are developed to gain the NSS value, the magnification degree, and the sliding depth to incur the singularity. The NRS is assessed using 1g model tests. The solutions are adopted to capture the response of the model piles, to detect new failure mechanism of Showa Bridge, and to check the safety of Christchurch bridges. The main conclusions are as follows: (i) piles are prone to response amplification, when subjected to lateral spreading or in sliding slopes. (ii) The NRS is only slightly affected by soil movement profiles and sliding depths. (iii) Showa Bridge collapsed from displacement amplification of back-rotated piles. Finally, (iv) the roller connections between girder and piers, and an integral abutment and piers are proved to be effective to curb the amplification. The amplified response needs to be assessed in practice to lessen failure of back-rotated piles.

scholarly journals Nonlinear response of laterally loaded rigid piles in sliding soil

2015 ◽  
Vol 52 (7) ◽  
pp. 903-925 ◽  
Author(s):  
Wei Dong Guo
Keyword(s):  
Nonlinear Response ◽  
Unit Length ◽  
Bending Moment ◽  
Lateral Spreading ◽  
Soil Movement ◽  
Passive Piles ◽  
Pile Deflection ◽  
Laterally Loaded ◽  
Sliding Soil

This paper proposes a new, integrated two-layer model to capture nonlinear response of rotationally restrained laterally loaded rigid piles subjected to soil movement (sliding soil, or lateral spreading). First, typical pile response from model tests (using an inverse triangular loading profile) is presented, which includes profiles of ultimate on-pile force per unit length at typical sliding depths, and the evolution of pile deflection, rotation, and bending moment with soil movement. Second, a new model and closed-form expressions are developed for rotationally restrained passive piles in two-layer soil, subjected to various movement profiles. Third, the solutions are used to examine the impact of the rotational restraint on nonlinear response of bending moment, shear force, on-pile force per unit length, and pile deflection. Finally, they are compared with measured response of model piles in sliding soil, or subjected to lateral spreading, and that of an in situ test pile in moving soil. The study indicates the following: (i) nonlinear response of rigid passive piles is owing to elastic pile–soil interaction with a progressive increase in sliding depth, whether in sliding soil or subjected to lateral spreading; (ii) theoretical solutions for a uniform movement can be used to model other soil movement profiles upon using a modification factor in the movement and its depth; and (iii) a triangular and a uniform pressure profile on piles are theoretically deduced along lightly head-restrained, floating-base piles, and restrained-base piles, respectively, once subjected to lateral spreading. Nonlinear response of an in situ test pile in sliding soil and a model pile subjected to lateral spreading is elaborated to highlight the use and the advantages of the proposed solutions, along with the ranges of four design parameters deduced from 10 test piles.

scholarly journals Probabilistic Prediction of Severity of Liquefaction Surface Manifestation Using Geotechnical and Geospatial Models

2017 ◽  
Author(s):  
Brett Maurer
Keyword(s):  
Land Use Planning ◽  
Ground Surface ◽  
Lateral Spreading ◽  
Hazard Mapping ◽  
Probabilistic Prediction ◽  
Damage Potential ◽  
Damage State ◽  
Site Assessment ◽  
Ground Failure ◽  
Surface Manifestation

The severity of liquefaction manifested at the ground surface is a pragmatic proxy of damage potential for various infrastructure assets, making it particularly useful for hazard mapping, land-use planning, and preliminary site-assessment. Towards this end, the recent Canterbury, New Zealand, earthquakes, in conjunction with others, have resulted in liquefaction case-history data of unprecedented quantity and quality, presenting a unique opportunity to develop fragility-functions for liquefaction-induced ground failure. Accordingly, this study analyzes nearly 10,000 liquefaction case studies from 23 earthquakes to develop functions that express the probability of exceeding specific severities of liquefaction surface-manifestation as a function of five different liquefaction damage measures (LDMs), of which three are based on geotechnical data and two are based on freely available geospatial data. The proposed functions have the same functional form, such that end-users can easily select the model coefficients for the particular damage state and LDM of their choosing. It should be noted that these functions are not to be used to predict lateral spreading, which requires LDMs other than those assessed herein. Lastly, the proposed functions are preliminary and subject to further development. In this regard, several thrusts of ongoing investigation are mentioned.

Pile response due to unsupported excavation-induced lateral soil movement

1996 ◽  
Vol 33 (4) ◽  
pp. 670-677 ◽  
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.

scholarly journals Behavior Characteristics of Single Batter Pile under Vertical Load

2021 ◽  
Vol 11 (10) ◽  
pp. 4432
Author(s):  
Jiseong Kim ◽  
Seong-Kyu Yun ◽  
Minsu Kang ◽  
Gichun Kang
Keyword(s):  
Bearing Capacity ◽  
Relative Density ◽  
Model Test ◽  
Ground Surface ◽  
Bending Moment ◽  
Vertical Position ◽  
Vertical Load ◽  
Behavior Characteristics

The purpose of this study is to grasp the behavior characteristics of a single batter pile under vertical load by performing a model test. The changes in the resistance of the pile, the bending moment, etc. by the slope of the pile and the relative density of the ground were analyzed. According to the results of the test, when the relative density of the ground was medium and high, the bearing capacity kept increasing when the angle of the pile moved from a vertical position to 20°, and then decreased gradually after 20°. The bending moment of the pile increased as the relative density of the ground and the batter angle of the pile increased. The position of the maximum bending moment came closer to the ground surface as the batter angle of the pile further increased, and it occurred at a point of 5.2~6.7 times the diameter of the pile from the ground surface.

scholarly journals Imaging ground surface deformations in post-disaster settings via small UAVs

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Richard L. Ybañez ◽  
Audrei Anne B. Ybañez ◽  
Alfredo Mahar Francisco A. Lagmay ◽  
Mario A. Aurelio
Keyword(s):  
Surface Deformation ◽  
Ground Surface ◽  
Point Clouds ◽  
Lateral Spreading ◽  
Fault Movement ◽  
Field Surveys ◽  
3D Point Clouds ◽  
Vertical Displacements ◽  
Resolution Imaging ◽  
Post Disaster

AbstractSmall unmanned aerial vehicles have been seeing increased deployment in field surveys in recent years. Their portability, maneuverability, and high-resolution imaging are useful in mapping surface features that satellite- and plane-mounted imaging systems could not access. In this study, we develop and apply a workplan for implementing UAV surveys in post-disaster settings to optimize the flights for the needs of the scientific team and first responders. Three disasters caused by geophysical hazards and their associated surface deformation impacts were studied implementing this workplan and was optimized based on the target features and environmental conditions. An earthquake that caused lateral spreading and damaged houses and roads near riverine areas were observed in drone images to have lengths of up to 40 m and vertical displacements of 60 cm. Drone surveys captured 2D aerial raster images and 3D point clouds leading to the preservation of these features in soft-sedimentary ground which were found to be tilled over after only 3 months. The point cloud provided a stored 3D environment where further analysis of the mechanisms leading to these fissures is possible. In another earthquake-devastated locale, areas hypothesized to contain the suspected source fault zone necessitated low-altitude UAV imaging below the treeline capturing Riedel shears with centimetric accuracy that supported the existence of extensional surface deformation due to fault movement. In the aftermath of a phreatomagmatic eruption and the formation of sub-metric fissures in nearby towns, high-altitude flights allowed for the identification of the location and dominant NE–SW trend of these fissures suggesting horst-and-graben structures. The workplan implemented and refined during these deployments will prove useful in surveying other post-disaster settings around the world, optimizing data collection while minimizing risk to the drone and the drone operators.

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