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By Timothy C. Siegel

This report presents the results of a synthesis on the design and analysis of ground improvement for liquefaction mitigation. The synthesis included an industry survey concerning the practice of ground improvement for liquefaction mitigation. Participation in the survey was solicited by advertisements in several trade magazines and by e-mail for the DFI membership. The survey participants numbered 150. Their professional roles include consulting engineers, specialty contractors, design engineers, government engineers, and academicians. They represent a variety of geographical areas including North/Central/South America, United Kingdom, Middle East, Caribbean, Hawaii, Japan, India, Egypt, France, Australia and New Zealand. Upon completion of the survey, several professionals in the field of liquefaction and ground improvement were interviewed for them to elaborate on the survey results. The interviews are included in the Appendix of this report. Financial support for the project was provided by DFI and Dan Brown and Associates PC. The concept of the liquefaction mitigation synthesis was developed by DFI?s Ground Improvement Committee in recognition that: (a) The results of recent research and post-earthquake reconnaissance have challenged previously longheld beliefs about liquefaction and associated mitigation techniques, and; (b) The DFI membership and the engineering/construction industry are interested to know if and how engineers and designers are subsequently adjusting their practice in consideration of recent research and post-earthquake reconnaissance. For more detailed information on recent research and post-earthquake reconnaissance, presentations are available from the State-of-the-Art Forum: Liquefaction Consequences and Mitigation that was held in St. Louis in 2012. A commentary of the state-of-practice in ground improvement for liquefaction mitigation (prepared by DFI?s Ground Improvement Committee) is included in this issue of the DFI Journal. The author would like to thank the participants of the survey and especially Mr. Mike Jeffries, Dr. Les Youd, and Dr. Ikuo Towhata for their willingness to share their expertise in interviews. The author also acknowledges Mary Ellen Bruce of DFI, Billy Camp of S&ME, Inc., and Marty Taube of DGI Menard (and Chair of DFI?s Ground Improvement Committee) for their signifi cant contributions.

Aug 1, 2013

Jan 1, 1986

By Steve Davidow, Nick Salisbury

"The Sunrise Powerlink project received numerous industry awards for excellence. The DFI C. William Bermingham Innovation Award recognized the innovative use of prefabricated steel micropile caps to increase safety, accelerate project schedule and minimize the project carbon footprint. DFI’s Outstanding Project Award (OPA) and World Cup of Micropiles Challenge Award honored the project as a whole and its positive outcome and industry example. Sunrise Powerlink involved construction of San Diego Gas and Electric’s (SDG&E’s) new 117 mile (188 km) 500/230 kilovolt transmission line from Imperial County to San Diego County, Calif. The alignment traversed a wide variety of geotechnical conditions, including desert, mountain and marine environments, and many of the 421 lattice tower structures used to carry the transmission lines were located in remote, rugged or environmentally-sensitive terrain.Micropiles were introduced as a solution to foundation construction in these challenging areas, which ultimately involved the design and application of Crux Subsurface Inc.’s patented steel micropile cap at 234 tower locations. This was the inaugural application of the technology, and a significant component to ensuring a successful project outcome. Foundation ChallengesThe alignment crossed a number of protected environments, including National Forest land, critical habitat for bald eagles and Peninsular big horn sheep, and numerous private properties. As a result of the remote, rugged terrain, it was initially determined that 75 lattice tower locations would not permit road construction access and would require helicopter-only construction techniques. A strict in-service date combined with long permitting lead times eventually increased this number to 234 sites. Preconstruction access constraints prohibited site-specific geotechnical sampling, so initial foundation designs were completed using only available seismic geophysical surveying and preliminary mapping data. The combination of these challenges required a foundation alternative that could accommodate variable subsurface conditions, required a minimal environmental footprint for installation, and featured lightweight materials and equipment that could be transported by helicopter."

Jan 1, 2014

Jan 1, 1991

By W. G. K. Fleming

The general history of piling is traced up to the present time with regard to the evolution of methods and materials. The processes have been strongly influenced by developments in basic equipment and industrial change. It is noticeable that in the twentieth century more progress has taken place than in the many previous centuries. It has been strongly influenced by the general development of Soil Mechanics. Test loading is probably the most effective way to assess the success of designs and many empirical relationships have been challenged through it. As we approach a new century it appears that it will be an age of rapid equipment development, with much enhancement of understanding of what has been done. Processes of automatic construction and testing will becoming commonplace. These changes will narrow the limits of conventional scatter that have come to be accepted and to a large extent will be driven by political efforts to curtail energy consumption, to raise standards of quality and reliability, and to conserve the environment. 1. Ancient history. Piling is an ancient art. Its first mention in history is from Herodotus, the first person to commit an account of his times to the written word in the years 557 to 479 BC. He evidently had a strong interest in engineering matters because he wrote of building, brick making, reinforced brickwork, river training, canal building, bridge construction, tunnelling and its acoustic detection and piling. The piling reference comes from Book 5 at paragraph 16.

Jan 1, 1999

Jan 1, 1992

Jan 1, 2001

This Workshop was held at the Doubletree Inn, Seattle, Washington from September 26 to 28, 1997. Run under the auspices of the Deep Foundations Institute (DFI), it was co-funded by the newly formed Japanese Association of Micropiles (JAMP), and the Federal Highway Administration (FHWA). The Workshop was jointly organized and facilitated by Fujita Research Corporation and ECO Geosystems, Inc., with close support by Donald B. Murphy Contractors, Inc. DFI kindly consented to publish these Proceedings. As is clear from the list of attendees, 42 specially invited engineers from all aspects of micropile technology were present, representing Japanese, European and American practice. This proved to be a most friendly and interactive group of people, who freely exchanged ideas, views and close comradeship, not only during the technical sessions, but (and especially!) during the numerous social events. Perhaps the best illustration of this came in Day 2 when the attendees were divided into five competing teams, each comprising representatives from the different geographic groupings. These teams had to quickly devise solutions to two technical problems (using standard data previously provided. A team of "referees" (who also acted as "coaches") later determined the most apposite response, based on constructability design concept, cost, schedule and so on. Not only were the winning team very liberal in distributing the prize (vintage California champagne) among themselves, but the whole Workshop soon benefited from their generous division of the spoils of victory.

Jan 1, 1997

Jan 1, 1997

Jan 1, 1994

By Amy B. Cerato, Shawn Allred, Tatiana Vargas

"Helical piles are deep foundation elements that resemble, and are installed like, a large steel soil screw — they have a slender steel shaft with one or more round helix bearing plates welded to the shaft to provide support to the structure they hold. Helical piles are rotated into the ground with a large torque motor and provide support through soil bearing on the helix bearing plates and along the shaft. The piles are available in many lengths and, due to their small footprint along with their ability to create minimal disturbance to surrounding structures, they are often used in urban settings for foundation repair, retrofitting existing buildings and for new construction projects. Helical piles are routinely installed as foundation elements in seismically active areas, such as New Zealand, Japan and the U.S.Anecdotal observations (e.g., from New Zealand, Japan and the U.S.) have shown that piles with a comparatively small cross-section and high anchoring capacity, such as helical piles, are beneficial for seismic resistance. This is presumably due to the pile’s slenderness, higher damping ratios, ductility and resistance to tipping uplift. In New Zealand, it was observed that helical pile foundations fared much better than driven and drilled concrete piles after the 2011 Christchurch earthquake. In a personal communication, Woods (2016) described that, out of the 300 structures in center city Christchurch that were supported by helical piles, fewer than 10 structures suffered significant structural damage. However, many structures supported by driven and drilled concrete piles were damaged to such an extent that they were condemned and subsequently demolished."

Jan 1, 2017

By Za-Chieh Moh

This paper presents a summary of the current pile foundation practice in Taiwan. Constructions of driven piles, drilled shafts, and barrette foundations are reviewed. This paper also briefly summarizes the pile works of four major construction projects in Taiwan, namely, Hsin-Ta Power Plant, Taichung Power Plant, Taipei Transit Systems, and Taiwan High Speed Rail.

Jan 1, 1996

By Christian Hoyme, Jochen Maurer

Most of the current foundation projects are suffering from disconnected information silos. In the first silo there is the planning of the project with corresponding data, presented by paper or digital drawings. Here will Building Information Modeling (BIM) be one of the trends for the future. We will see more and more projects leaving the “old way” of 2D drawings and moving into 3D planning including metadata of the foundations. But even with a perfect BIM model of a jobsite, we are not at final end of digitalization. While execution of the project at the jobsite, a second data silo is evolving. Data collected directly from construction equipment and manual measurements is currently undervalued in most projects. Paper is passed to the equipment operator and major data from measurements on site are noted on paper and digitized afterwards. Automatically collected data is not be used to create site progress reports or similar report. So, the real “data” just flows around without connection to any other data already existing in projects. And then the third silo arises: The documentation of the project. Data collected on paper es reentered to create some basic documentation of the work handed over to the client. Spreadsheet software is still the “tool-to-be-used” to create at least some documentation. Finally, the documentation is not connected to the data created while planning and not connected to the automatically collected data from the jobsite. A connected jobsite in the foundation industry must link these information silos and have to create a full data-workflow from the design through the execution to the as-built documentation. INTRODUCTION Building information modelling (BIM) is currently the most popular term of construction business in Germany and probably all over the world. But as often there are many different definitions out there and everyone has his own definition or at least understanding what BIM is about. But for sure it is the most relevant for the construction industry in the near future. Most popular is the digital twin for the upper structure of a building. In most cases the BIM models just shows the building itself, but there is more to be implemented. For example: projects where a special foundation is needed, BIM should include also the foundation elements with meta data. There are several advantages. Not only the clash detection of anchors, but also the possibilities to check the interaction with neighbor constructions, power lines and so on are a use case. For sure most of the special foundation elements are not relevant for the whole lifecycle of a building. But during construction and later the demolition the information about the hidden elements is important and gives a benefit to all stakeholders. In the future there will be not the question: “What is already in the ground?”. The risk for following construction projects on the same ground will be minimized.

Jan 1, 2019

By Kul Bhushan

This paper presents the results of lateral load tests on 0.61-m to 1.27-m (24 to 50-inch) diameter drilled and cast-in-place piers in San Diego area residual/formational soils. The test piers were installed and tested in the following soils: Decomposed Granitic Rock (Ktd), Stadium Conglomerate (Tst), and Friars Formation (Tf). Lateral loads of up to 845 KN (190 kip) were applied to the piers in residual granitic soils, and loads up to 1780 KN (400 kip) were applied to the piers in Stadium Conglomerate and Friars Formation. The tests were conducted by jacking against adjacent piers and monitoring the lateral load and lateral deflection at the ground line. Test results indicate that ultimate lateral pile capacities of up to 1800 KN (400 kip) can be obtained for 0.61 m (24-inch) drilled piers with penetration of 3 to 6 m (10 to 20 ft) in the residual/formational soils tested. Lateral load analyses using p-y curves for very dense sand significantly overestimate the observed lateral deflections. For lateral load analyses using dense sand p-y curves, p-multipliers that increase the lateral soil stiffness (p-y curves) by 2 to 8 times are required to match the load-deflection behavior measured in the test piles. When applied to the dense sand p-y curves, the p-multipliers provide a more accurate prediction of load-deflection behavior in the residual/formational soils, and can result in shorter required pier penetration and significant savings in foundation cost.

Jan 1, 2002

By Brian Wilson, Franz-Werner Gerressen

"Cutter Soil Mixing, also known as CSM, was developed in Europe as an alternate method of Deep Mixing to the more traditional single and multiple auger techniques, and brought to market by Bauer Maschinen GmbH (Bauer), towards the end of 2003. Initial development of the technique had been completed in a joint venture between Bauer and Bachy Soletanche. In 2004 the concept was introduced to the North American market. Continued development of the method and demonstration of its versatility, both in terms of applications and applicable soil types has seen a steady growth in the number of designs incorporating the approach, and contractors offering the technique. This paper provides a brief overview of the variety and size of projects and applications where the method has been adopted, discusses some lessons learned with respect to equipment operation as well as the improvements that have been introduced to the equipment, and briefly reviews the current state of practice, as well as some of the associated on-going research and development.BACKGROUNDCutter Soil Mixing (CSM) is a technique for deep soil mixing that was initially developed as a collaborative effort between Bauer Maschinen (Bauer) and Bachy Soletanche, but which ultimately resulted in the separate development of two somewhat different brands of CSM tool. The Bauer brand of CSM entered the European market in 2004, and was first promoted in the North American market in late 2004, with the first project starting in 2005. The Bachy Soletanche brand, sometimes referred to as “Geomix” was first marketed in Europe in 2005 and the first model introduced in North America in 2007.The development of the Cutter Soil Mixing technique utilized the experiences gained from Trench Cutter/Hydrofraise equipment, developing a technique that incorporates two cutting wheels rotating about a horizontal axis as opposed to the more conventional deep soil mixing approach which utilizes augers and mixing paddles rotating about vertical axes. Whereas the Trench Cutter/Hydrofraise technique excavates the soil from within a panel, and supports the open hole using a bentonite slurry, the CSM technique cuts and displaces the soil whilst pumping a slurry/grout directly into the soil through a port located between the wheels. The combination of cutting the soil while introducing an appropriate volume of slurry effectively fluidizes the column of soil around and above the cutter head. While this process achieves a high degree of mixing, even on the downward cutting stroke, thorough in-situ mixing typically occurs on the withdrawal stroke, when most of the slurry is added."

Jan 1, 2015

Jan 1, 1994

By Tony Amis, Marco Barla, Alice Di Donna

"Energy geostructures are becoming an increasingly popular solution around the world for Developers looking to reduce CO2 and system running costs. Energy geostructures are geotechnical structures that provide both the important role of structural stability while also acting as a heat exchanger with the ground, enabling the supported buildings and or infrastructure to be heated and cooled using the principle of low enthalpy geothermal systems. The main advantage of this innovative technology with respect to standard geothermal plant is the reduction of the initial installation costs and construction schedule benefits, compared to installing conventional geothermal solutions, largely due to the additional use of structures which would be constructed in any case. However, it is important with respect to energy geostructures that additional aspects need careful consideration. For this very reason, several research studies have been carried out over the last decade on this subject and a number of real case studies have been monitored and analysed. The key difference with respect to conventional shallow geothermal systems are mainly related to the geometry, which is imposed by the geotechnical project, and the need to ensure that the primary structural role is always guaranteed. Special boundary conditions, the reduced depth, the influence of atmospheric external temperature can also play an important role for energy geostructures. They can affect, both energy efficiency and, the geotechnical behaviour because of the possible thermal induced mechanical effects. This paper presents a picture of the current situation regarding energy geostructures and their peculiar features, and collects available data to provide a reference framework. Data has been collected from literature and personal communications and then processed to provide easy-to-read charts useful for practical consultation at a glance. This paper provides, an indication of the distribution of such systems worldwide, their spread in time, and a global view of their actual efficiency from the structural, energy, economic and environmental point of view.1. IntroductionEnergy geostructures are becoming an increasingly popular consideration around the world. Energy geostructures are geotechnical structures with a dual role of providing structural stability and the ability to exchange heat with the ground, to provide low carbon heat and coolth to supporting and or adjacent buildings and infrastructure, using the principle of low enthalpy geothermal systems (Barla and Di Donna, 2016; Laloui and Di Donna, 2013). A closed circuit of high density polyethylene (HDPE) pipes is embedded in the concrete, and a heat carrier fluid circulates through them exchanging heat with the ground. The HDPE pipework circuit inside the geostructure is linked to one of the above buildings or infrastructure through a heat pump, which adapts the temperature of the circulating fluid to the heating (winter mode) and cooling (summer mode) needs. In this way, heat can be injected into the ground during summer and extracted from it during winter. In principle, all structures in contact with the ground can be used as energy geostructures. The first examples of energy geostructures date back to the eighties in Austria and were mainly piles and shallow foundations. A decade later, Henderson et al. (1999) reported on what would appear to be the first successful use of geothermal energy piles in the US, with loops incorporated into the foundation for a hotel in Geneva, New York. As was their use in this New York case history, the typical geothermal energy pile application is used in conjunction with additional closed loop boreholes to provide the required energy capacity for a structure. Interestingly the report concludes that the geothermal energy piles had a better heat transfer performance than the borehole field. The first energy walls appeared slightly later, while still today only a few experimental cas"

Jan 1, 2017

By David H. Sanders, Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan

Large-diameter drilled shafts (DS) are a critical part of a seismic-resistant system, and therefore it is important to be able to accurately model lateral resistance. To undertake the lateral load analysis of largediameter DS, a finite-difference p-y analysis program, NVShaft, is being developed at the University of Nevada Reno. Validation of the new program involved numerous p-y analyses using commercially available programs. Subsequent comparisons suggested the program's ability to yield reasonable predictions for typical diameter DS. Based on the I-15/US 95 load test program carried out in Las Vegas, NV, this study presents the evaluation of NVShaft in Nevada’s subsurface condition. Lateral load analyses of a 2 ft and an 8 ft diameter DS were attempted using NVShaft. The location of the applied lateral loads and the presence of cemented soil-layers were incorporated in the modeling. A good agreement between NVShaft prediction and the measured response was found for the 2 ft diameter DS. For the 8 ft diameter DS, a stiffer response was predicted. The inspections of the moment-curvature characteristics at different load levels suggested cracked response of the concrete due to prior axial load testing may be one of the reasons behind the deviation.

Jan 1, 2004

By Moi Arzamendi, Jose Ramirez, Kenneth Kniss, Sunil Arora, James Gingery

Construction of a new approach embankment for a railroad bridge over a river in Southern California required placing up to 12 ft of fill over soft to medium stiff silts and clays along an approximate 1,500-ft long stretch. The embankment, situated within a narrow railroad right-of-way between an existing live track and existing buildings, would have been susceptible to excessive settlement that could damage existing buildings and numerous underground utilities if regular weight soil fill had been placed over the unimproved ground. To limit total and differential static settlements to tolerable levels, a design was developed using a combination of mechanically stabilized earth wall with lightweight cellular concrete fill and rigid inclusions ground improvement. This paper describes the design of the ground improvement system, construction methods used, and challenges of working next to live railroad traffic. Ground improvement quality control and assurance measures, and verification of performance by settlement monitoring are also addressed. INTRODUCTION AND BACKGROUND The 0.9-mile San Diego River Double Track (SDRDT) project is located on the Los Angeles-San Diego- San Luis Obispo (LOSSAN) Corridor in San Diego, California. The project includes the replacement of the existing 900-ft long single track railroad bridge over the San Diego River with twin double track structures. Construction of the project is phased and closely coordinated with the associated Mid-Coast light rail project (San Diego Trolley Blue Line Extension). The new bridge is a 7-span, twin steel, through girder structure supported by six cast-in-place reinforced concrete pier caps and two abutments. The large diameter cast-in-drilled-hole (CIDH) foundations are up to 9 ft in diameter, with upper portions encased in a 1.5-in.-thick permanent steel casing. The north abutment approach embankment includes a mechanically stabilized earth (MSE) retaining wall up to approximately 10 ft high and 1,520 ft long. This paper focuses on the design and construction of the north approach embankment. The project site is characterized by challenging geotechnical and seismic conditions. The site contains liquefiable soils interbedded with soft cohesive soils, underlain by competent layers of sand/gravel/cobble and other sedimentary formations. Static settlement of the new railroad, crossing utilities and adjacent buildings was a primary design concern for the north approach embankment.

Jan 1, 2018