It is not intended to be a comprehensive technical report on the ground improvement programme gip in canterbury. The project consists of an immersed singletube tunnel under the strait and two cutandcover tunnels at the ends of the immersed part. For simplicity within this chapter, ground improvement methods, volumes i and ii, fhwa nhi06019 and fhwa nhi06020, august 2006 will be referenced as ground improvement methods. Chapter 6 seismic design washington state department of. It is hoped that this document will 1 aid the owners and designers in the planning of ground improvement for liquefaction remediation near existing lifelines, and 2 identify those areas.
A study of effectiveness of ground improvement for liquefaction mitigation bin tong iowa state university follow this and additional works at. For the liquefaction ground improvement decision, the tree begins with a set of branches representing the individual treatment methods or depths identified. When evaluating, recommending and specifying various ground improvement methods for liquefaction mitigation, practitioners should understand the fundamental mechanics involved and applicability and limitations of the. Key words liquefaction, bridge abutment, ground failure, soil improvement, seismic design 18. Ground improvement of soils prone to liquefactionpdf. Drained timber pile ground improvement for liquefaction. H ence, a liquefied ground is no longer considered stable and fit for construction of structures. Ground improvement using sand columns to mitigate liquefaction a case study 4 fig. The results presented in figure 5 demonstrate significant reda uction in liquefaction vulnerability provided by shallow rap ground improvement illustrating the benefits produced by raps for densifying clean sand and sand with silt. Ground improvement techniques for mitigation of liquefaction hazards 701 zone levels iii, iv and v.
Ground improvement of soils prone to liquefaction page 6 introduction 5 1. It is hoped that this document will 1 aid the owners and designers in the planning of ground improvement for liquefaction remediation near existing lifelines, and 2 identify those areas where more study is needed. Importance of soil liquefaction after liquefaction, the soil no longer behaves as an inactive grid of particles. Ground improvement and liquefaction mitigation using driven. In short, ground improvement is executed to increase the bearing capacity, reduce the magnitude of settlements and the time in which it occurs, retard seepage, accelerate the rate at which drainage occurs, increase the stability of slopes, mitigation of liquefaction potential, etc. Propagating branch sets typically include a liquefaction parameter, a horizontal movement parameter given liquefaction and a damage parameter given movement. The ground can be improved by adapting certain ground improvement techniques. Ground improvement is carried out for various objectives.
Proceedings of the institution of civil engineers ground. Groundimprovement methods are those that are capable of improving certain characteristics e. The ground improvement that surrounds the castinplace piles extends to a depth of about 16 m. The framework is intended to be technologyneutral to allow for the best application of technology to the project needs. Mitigation of liquefaction and associated ground deformations. When liquefaction occurs, the strength of the soil decreases and the ability of a soil deposit to support the construction above it. National design guidelines for ground improvement of soils prone to liquefaction 2 the guidelines are module 5 in the mbie nzgs guidance series of geotechnical modules that have been developed by mbie and nzgs with support from nz and international consultants, contractors and universities mbie, 2016a. Proceedings of the institution of civil engineers ground improvement, volume 162, issue 2, 1 may 2009 6979 densification of granular soil by dynamic compaction authors. Ground improvement methods for liquefaction remediation request. The factors and phenomena governing the performance of the improved ground were identified and clarified.
Commentary guidelines for ground improvement using. Not all recommendations are applicable to all projects or every type of ground improvement, but this document presents a con. Horizontal soil mixed beam ground improvement as a. Mar 06, 2015 usually, insitu test are performed to evaluate the liquefaction potential of a soil deposit before the improvement was attempted. Vibrocompaction increases the density of the soil by using powerful depth vibrators.
The feasibility of using ground improvement at existing highway bridges to mitigate the risk of earthquakeinduced liquefaction damage has been studied. Resin injection as a ground improvement method 2 the aim of this study was to examine on a formal basis whether resin injection is a viable form of ground improvement, primarily for liquefaction mitigation. Graduate thesis or dissertation ground improvement and. Ussd static liquefaction workshop agenda wild apricot. Remediating structures affected by serious ground issues, such as liquefaction, poor compaction or settlement, has up until now been a complex process. The improved ground was constructed using a deep cement mixing method. Earthquakes of this magnitude can cause structural and ground failures from liquefaction. Horizontal soil mixed beam ground improvement as a liquefaction mitigation method beneath existing houses.
Study on liquefaction of soil national institute of. A number of methods can be used to verify the effectiveness of soil improvement. Request pdf ground improvement methods for liquefaction remediation soil liquefaction continues to be a major source of damage to buildings and. Improvement of potentially liquefiable soil beneath and surrounding structures is currently feasible. Chapter 16 ground improvement for mitigating liquefactioninduced. Supa centa ground improvement the northwood supa centa in christchurch had suffered from serious earthquake damage including liquefaction and required extensive ground improvement work to densify the soil beneath the structures to help bring the existing building back to level. Ground improvement method an overview sciencedirect topics. Pdf soil improvement to counter liquefaction using. Technical feature guidance for drafting specifications. The goal of the technical commentary is to highlight the findings of the recent studies on this matter. Liquefaction of foundation soils imposes geotechnical hazards primarily in the form of loss of bearing capacity and permanent ground deformations. Ussd static liquefaction workshop agenda july 09 10, 2019 aecom building 6200 s. According to the result, the cost of countermeasure can be reduced significantly. The risk of liquefaction and associated ground deformation can be reduced by various ground improvement methods including densification, solidification e.
While the ground improvement programme was driven by the needs of the canterbury community following the 20102011 earthquakes, the lessons learned are applicable globally. Jul 06, 2015 soil liquefaction seminar and ppt with pdf report. Liquefaction is one of the cardinal concern to the geotechnical engineers as well as those involved in the building and development of structural foundations. The scope of the chapter is limited to practical aspects of case history project and covers following. Sample problems to demonstrate each design procedure are included in the appendices. We have provided soil liquefaction seminar and ppt with pdf report. Vacuum consolidation is used for improving soft soils by using a vacuum pump.
Ground improvement techniques for mitigation of liquefaction. Usually, insitu test are performed to evaluate the liquefaction potential of a soil deposit before the improvement was attempted. With this method, wider spacing of the lattice can be applied and liquefaction layer beneath the stabilized bodies can be left. The construction of the road fixedlink crossing between preveza and aktio on the northwestern coast of greece has recently been completed. These failure mechanisms include lateral spreading. Mainmark was able to successfully remediate the retail centre back to. The technical commentary does not intend to define suitable methods or design equations for ground improvement design in potentially liquefiable soils. The main goal of most soil improvement techniques used for reducing liquefaction hazards is to avoid large increases in pore water pressure during earthquake shaking. The ground improvement programme earthquake commission. 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. There have been major advances occurred in the past in understanding as well as practicing of engineering treatment of seismic soil liquefaction and assessment of seismic site response.
Soil liquefaction, ground failure or loss of strength that causes otherwise solid soil to behave temporarily as a viscous liquid. Owing to the potential for instability following liquefaction, geotechnical engineers often prescribe ground improvement programs to densify, drain, andor reinforce liquefiable soils. Ground improvement techniques for stabilization of. Soil improvement to counter liquefaction using colloidal silica grout injection article pdf available in journal of environmental protection and ecology 201. Pdf liquefaction of soil results when there is hardly any shear strength left in the soil to resist the shear stresses induced when subjected to.
Presented also are the most widely accepted methods for evaluating the liquefaction potential of cohesionless oils in level ground, for estimating earthquakeinduced settlements and. With the knowledge of the existing ground characteristics, one can then specify a necessary level of improvement in terms of insitu test parameters. Commentary guidelines for ground improvement using discrete. Vibroflotation involves the use of a vibrating probe that can penetrate granular soil to depths of. Boulanger and idriss 2014 liquefaction triggering methodology. The selective methods like vibro compaction, dynamic compaction were. To strengthen the subsoil properties in terms of its bearing capacity, shear strength, and. This can be achieved by densification of the soil andor improvement of its drainage capacity. Ground improvement techniques were employed to mitigate liquefaction hazards. Engineering of ground for liquefaction mitigation using. Preloading method is used to remove pore water over time. The immersed section is constructed of eight precast rectangular concrete elements placed on the. Report on ground improvement costs for cleared sites in. Commentary on the selection, design and specification of.
Based on improvement objectives and ground and site conditions. Engineering of ground for liquefaction mitigation using granular. The ground improvement programme is a significant step forward in understanding the effects of liquefaction damage and ways to reduce damage in future earthquakes. Soil liquefaction during recent largescale earthquakes.
The main purpose of this report is to reduce the damage due to liquefaction disaster by introducing some ground improvement. Earthquake geotechnical engineering practice series. Developed jointly by mbie and the new zealand geotechnical society, module 5 is part of the earthquake geotechnical engineering practice series and relates specifically to ground improvement of soils prone to liquefaction. The strength and stiffness of the liquefied soil are significantly decreased, often resulting in a variety of structural failures.
Report on ground improvement costs prepared for earthquake commission 22 june 2015 page 3 of 69 1. Ishihara 1985 recognised that athick nonliquefying crust overlying soils would liquefying reduce the consequences of liquefaction i. National design guidelines for ground improvement of soils. Foundations in liquefiable soils need to be designed to withstand these hazards, or ground improvement measures need to be implemented to mitigate the resulting impacts.
Liquefaction countermeasures by shallow ground improvement for houses and their cost analysis kazuo tani, takashi kiyota, katsuya matsushita, takao hashimoto. The pressures generated during large earthquakes with many cycles of shaking can cause the liquefied sand and excess water to force. The geotechnical manual documents the departments standards of practice for geotechnical investigations, design, and reporting. Note that the foundation loads caused by flow failure are affected by the foundation details and therefore may require some design iteration between the geotechnical and. The fundamental ground improvement mechanisms for liquefaction mitigation include densification, drainage, and reinforcement.
The phenomenon occurs in watersaturated unconsolidated soils affected by seismic s waves secondary waves, which cause ground vibrations during earthquakes. A study of effectiveness of ground improvement for. Request documents that are not currently available by emailing. Report on ground improvement costs for cleared sites in the. Insitu techniques are popular because of the limitations of many laboratory techniques. Ground improvement northwood supa centa, christchurch, nz the supa centa had suffered from serious earthquake damage including liquefaction and required extensive ground improvement work to densify the soil beneath the structures to help bring the existing building back to level. From the above consideration, it can be concluded that soil under consideration is susceptible for liquefaction. Ground improvement solutions to mitigate liquefaction. Soil liquefaction and the associated ground deformations have caused significant damage to many infrastructure and builtup areas. Chapter 11 ground improvement geotechnical design manual page 7 of 7 11. Soil liquefaction occurs when a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid.
If ground improvement is needed, the geotechnical engineer also provides a ground improvement design. Rammed aggregate pier ground improvement as a liquefaction. Ground improvement for liquefaction mitigation at existing. Specification of ground improvement for residential properties in the. Lessons learnt from the mackays to peka peka expressway, new zealand 5 figure 4 example pre green vs post blue cpt comparisons and design lines.
Introducing terefirm resin injection the next generation in ground improvement, liquefaction mitigation and bearing capacity enhancement solutions. This new ground improvement method considering confining effect is called cgi method. However, the depth upto which it is susceptible for liquefaction, generally termed as liquefaction depth, needed to be. While research on liquefaction continues, the geotechnical. Ground improvement techniques for liquefaction remediation. Liquefaction is the process that leads to a soil suddenly losing strength, most normally as a result of ground shaking during a large earthquake. Pdf stone column ground improvement against liquefaction. Decision analysis for liquefaction ground improvement. Liquefaction can occur when earthquake ground motions raise porewater pressures in loose, sandy soil, resulting in a substantial decrease of soil strength. A study of effectiveness of ground improvement for liquefaction. Soil liquefaction can also exert higher pressure on retaining walls, which can cause them to slide or tilt. Use of gravel drains is a rather recent development compared with the more traditional soil densification approaches. This has been achieved through a series of trial injection panels, where preinjection and postinjection soil density and stiffness. Liquefaction can be manifested either by the formation of boils and mudspouts at the ground surface, by seepage of water through ground cracks or in some cases by the development of quicksand conditions over substantial areas 1.