Apr 26, 2012 a coupled pile soilstructure interaction spsi analysis method is presented to study the liquefaction effects on lateral pile behavior of the highway bridges. Thus the observations and conclusion from this study are thought to also apply to the majority of shallow foundations. In contrast, very simple pseudostatic methods are used in engineering practice to determine. Design and construction of a largescale laminar box of 2 m. The pacific earthquake engineering research center peer is a multiinstitutional research and. Effects of liquefactioninduced ground displacements on pile performance in the 1995 hyogokennambu earthquake. This report describes the development of a performancebased framework to create seismic designs of pile group foundations that consider all potential levels. Effects of liquefaction on inelastic demands on extended pile. Seismic design of highway bridge foundations with the effects of liquefaction since the 1995 kobe earthquake. Seismic design of deep foundations introduction observations from recent earthquakes have shown that pile foundations are susceptible to significant damage when subjected to loads induced by large seismic events. Lateral spreading near deep foundations and influence of soil. Thus, use 75% of seismic vertical reactions foundation design 17. This book is a comprehensive contribution to the stateoftheart design of building foundations that are prone to seismic effects. Design of extended pile shafts for the effects of liquefaction.
The analysis of pile foundations for liquefaction effects may include nonlinear equivalent static. Influence of site liquefaction on seismic design of bridge. The seismic design of pile foundations in liquefiable soils poses very difficult. As a consequence, an effective seismic design of pile foundations has not. Seismic design of highway bridge foundations with the. An attempt has been made in this paper to summarize the currently available information on design of shallow foundations under seismic loading. Performancebased design factors for pile foundations. This report provides basic knowledge about liquefaction of cohesionless soils under seismic loading. Liquefaction can cause lateral spreading beside the banks of rivers and waterways. Let us consider the case of pile foundations in level ground comprising a soft, horizontal soil layer in which no soil liquefaction occurs, overlying a. The design should be safe and at the same time economical. Seismic design of pile foundations for different ground conditions. Pile design for lateral loading where liquefaction does not occur.
Pile models were installed in the ground, and the force acted on the piles were measured. This report presented the progress in the seismic design of highway bridge foundations with the effects of liquefaction and its background since the 1995 kobe earthquake, in relation to the liquefaction potential assessment, the ductility design of pier and abutment foundations for liquefaction, and seismic design of pier foundations for. Force on a pile eq on unloaded pile pile supporting structure. Seismic design of pile foundations for liquefaction effects 279 capacity,andnonlinearshapeofthesespringelementsmaybemadefromestimatesof. Improved understanding of liquefaction effects on shallow. Presented also are the most widely accepted methods for evaluating the liquefaction potential of cohesionless oils in level ground, for estimating earthquakeinduced settlements and for analyzing slope stability against flow slides. Apr 20, 2016 in other words, liquefaction potential of the chosen site should be lo. This project was motivated by the large costs associated with the construction of new pile foundations and the remediation of existing foundations in areas where liquefaction and lateral spreading are a concern. Jun 02, 2019 numerical analyses have developed the effects of liquefaction triggering on seismic response of structures and soil stiffness, and the results of analysis illustrated a robust framework for mitigation of pile foundations by using recent design earthquakes. The southwestern tip of indiana is close to the new madrid seismic zone, which generated the large earthquakes of 18111812. The seismic design of foundations for structures depends on dynamic bearing capacity, dynamic settlements and liquefaction susceptibility of soil.
The processes of soil liquefaction and soilpile interaction during earthquakes are extremely complex. Earthquake geotechnical engineering, 4 th international conference on earthquake geotechnical engineering invited lectures, k. The seismic response of pile foundations is a very complex process involving inertial interaction between structure and pile foundation, kinematic interaction between piles and soils, seismically induced porewater pressures pwp and the nonlinear response of soils to strong earthquake motions. Effects of soil liquefaction on pile foundation and its. The phenomenon of liquefaction and how it should be evaluated continues to be the subject of. Design issues in addition to the conventional design issues of axial load capacity, settlement, structural adequacy and durability under static imposed loadings, the design of deep foundations in seismic areas requires consideration of the following factors. Liquefaction effects on pile foundations last updated on wed, 04 feb 2015 seismic design eurocode soil liquefaction is the association of phenomena like piping, boiling, ud volcanoes etc. In this paper, emphasis is placed on the seismic design of pile foundations, a foundation type often used at sites where liquefaction is a potential problem. Pdf seismic design of pile foundations for liquefaction effects. This helps expedite compliance to international design codes for oil and gas, and wind turbine platform structures subject to environmental and mechanical loads. Behavior of piles in liquefiable soils during earthquakes. The moment distribution approximated based on the design guide sugimura, 1988 by assuming the total lateral force resisted by piles to be1. Lq soil it is incorrect to displace the pile head to match the. Effects of soil liquefaction on pile foundation and its remedies.
It is well known that loose sandy soils and sandy silts are particularly vulnerable from a liquefaction point of view. Seismic risk management of piles in liquefiable soils. The seismic design of pile foundations is currently performed in a relatively simple, deterministic manner. The effects of soil liquefaction on the built environment can be extremely damaging. This report presented the progress in the seismic design of highway bridge foundations with the effects of liquefaction and its background since the 1995 kobe earthquake, in relation to the liquefaction potential assessment, the ductility design of pier and abutment foundations for liquefaction, and seismic design of pier foundations for liquefactioninduced ground flow. Before proceeding to the design of the foundation, the susceptibility of the underlying soil to liquefaction is evaluated. There are several methods available to engineers for seismic design and. Buildings whose foundations bear directly on sand which liquefies will experience a sudden loss of support, which will result in drastic and irregular settlement of the building causing structural damage, including cracking of foundations and damage to the building structure, or leaving the structure.
Seismic design of pile foundations for liquefaction effects 297 pushover analyses of the global bridge structure can be used to estimate this load transfer behavior. Numerical analyses have developed the effects of liquefaction triggering on seismic response of structures and soil stiffness, and the results of analysis illustrated a robust framework for mitigation of pile foundations by using recent design earthquakes. The potential of liquefaction and lateral spreading increase the likelihood of damage in both. Pile foundations for such structures, as shown for example in figures 1 and 2, are normally required in the presence of softer more compressible soils, where design concerns relate to. Seismic design of highway bridge foundations with the effects. Soils and foundations, special issue on geotechnical aspects of the january 17, 1995 hyogokennambu earthquake, tokyo, japan.
Sacs pile structure design, offshore structure foundations. Seismic design of pile foundations for liquefaction effects 293 thebene. Design examples pilepier foundations view of cap with column above and piles below foundation design 29 passive resistance see figure 4. The objective of the investigation is to develop a subsurface geological model for the site so as to reliably predict the future behaviour of the ground at the site so that the designer can create a suitable. Design safe foundations for offshore structures using sacs pile structure design. This book is a comprehensive contribution to the state of theart design of building foundations that are prone to seismic effects. Various recommended design methods for pile foundations affected by liquefaction e. Instructional materials complementing fema p751, design examples foundation design 3. Small effects may be neglected ground improvement may be considered february 11, 2015 bssc colloquium.
Pdf procedures for the seismic design of pile foundations for liquefaction effects are presented with emphasis on the conditions relevant to. Pile design for axial loading, including the possible effects of liquefaction. There are several methods available to engineers for seismic design and analysis of piles. Liquefaction effects on lateral pile behavior for bridges. Based on those results, a seismic design technique of bridge foundations for liquefaction. Reduce the fatigue risk of foundations by determining response from cyclic environmental loads. Liquefaction effects on pile foundations seismic design.
Seismic design of pile foundations for liquefaction effects. Lateral spreading near deep foundations and influence of. Pile soil interaction is simulated by the dynamic nonlinear py method including the effect of liquefaction. Piles are considerably long element and the soil around it offers an excellent support. Of particular emphasis in this book is the seismic design of pile foundation that is prone to subsoil liquefaction and loss of bearing capacity. Estimate the bending moment for resonant conditions via equations 611. Seismic design considerations for pile design according to international and indian codes of practice 4. Following are the effects of liquefaction on pile foundations which are discussed in details.
Cracks open up along the banks, which can extend back on to properties and building foundations. Stone columns for liquefaction mitigation and pile groups foundation assessment were investigated by the osu team, while dsm and large diameter pilesshafts alternatives were investigated by the ucd team. Liquefaction also contributes to other ground effects, such as settlement and lateral spread. Missouri university of science and technology scholars mine.
Hence, the design of piles against earthquake loads and soil liquefaction is a very difficult task. The shear wave velocity in the upper liquefied layer is now vs1liq vs1v. Liquefaction seismic design eurocode eurocode standards. A coupled pilesoilstructure interaction spsi analysis method is presented to study the liquefaction effects on lateral pile behavior of the highway bridges. For the design of foundations in seismic zones, knowledge in a wide spectrum of disciplines such as soil dynamics, geology, seismology and structural dynamics is required. If deep pile foundations are being considered, the investigation also needs to study at least 10 pile diameters into the bearing stratum.
Moreover, the seismic design of pier foundations for liquefactioninduced ground flow was newly prescribed. Effect of steel casing thickness and pile cap on pile performance. Most analysis for design of shallow foundations under seismic loads are based on the assumption that the failure zones in soil occur along a static failure surface. Soil liquefaction significantly affects the dynamic response characteristics of a bridge structure founded on piles e. Soil liquefaction is the association of phenomena like piping, boiling, ud volcanoes etc. Three different combinations design cases of pile head constraints and soil conditions were considered, which are commonly encountered in practice. The dynamic bearing capacity problem has been attracting the attention of researchers during the last about fifty. Pilesoil interaction is simulated by the dynamic nonlinear py method including the effect of liquefaction. Fugros comprehensive earthquake engineering services combine wideranging, stateoftheart analysis and modelling techniques to predict the effects of seismic activity on foundations and structures and to inform appropriate geotechnical design and engineering solutions. In contrast, very simple pseudostatic methods are used in engineering practice. Design of piles, liquefaction, lateral spreading, py method introduction one of the most damaging effects of earthquakeinduced soil liquefaction is the lateral spreading of soils.
Procedures for the seismic design of pile foundations for liquefaction effects are presented with emphasis on the conditions relevant to bridges. Seismic design of pile foundations for liquefaction effects 279 capacity, and nonlinear shape of these spring elements may be made from estimates of the soil strength and stiffness parameters. Effects of liquefaction on inelastic demands on extended. Two local subsystems for a bridge are discussed in detail. Evaluation of the effects of liquefaction on concrete pile.