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By Justin Lukens, Di Stasim Jeffrey, Frank Di Salvo

Columbia University’s Manhattanville Campus expansion includes the construction of two new business school buildings. The new buildings require development of an entire city block bound by 12th Avenue, W 131st Street, W 130th Street and Broadway in Upper Manhattan. A support of excavation (SOE) package was first released, followed by a foundation package. The SOE package consisted of approximately 100 soldier piles and 280 anchors, up to 215’ long, to support a cut anywhere from 30’- 50’ below street level. The foundation package alone included approximately 1600 drilled micropiles. Given the breadth of the work scope, Hayward Baker Inc and Moretrench joint ventured on these two projects to bring sufficient knowledge and work resources to complete the work in an efficient and timely manner. This included working with the Owner/Engineer to propose different means and methods for construction to significantly reduce the schedule while meeting the design intent, such as large diameter (36” diameter) augercast piles in place of conventionally drilled soldier piles and large hollow-bar micropiles (103/51 bars) in lieu of pressure-grouted micropiles. The anchors, ranging from 3 to 22 strands, were used for earth retention through both soldier pile and lagging walls and existing slurry walls. These anchors were complicated based not only on their size and length, but also the need to drill some of them under the historic Studebaker building. The overall magnitude of the project with considerations to resource management and material lead times will be addressed, highlighting critical strengths provided by the Contractor to ensure project success. The scope of work discussed in this paper was executed under two separate competitive bid contracts. The first contract included the support of excavation work and the second contract included the foundation package. The support of excavation comprised of drilled soldier piles (performed by Case Foundation as a subcontractor to the JV), driven soldier piles, driven sheet piles, hollow bar tiebacks, multi-strand tieback anchors and micropile soldier piles. The foundation package consisted of drilled micropiles. Due to the large scope of work and critical schedule requirements of the project, the JV had to think outside the box and present value engineered alternates to expedite installation durations.

Jan 1, 2019

By Yazn Khasawneh Ph. D. P. E., Will Tjaden, Spencer E. Ness P. E., Mohammed Nasim Ph. D. P. E.

Wind turbine components undergo many loading cycles during their operational life. Additionally, wind turbines may undergo extreme loading conditions from natural hazards, mechanical failures, or emergency stops. Current design practice for the foundations of wind turbines accounts for these complex loading conditions through a simplified pseudo-static approach based structural loading combinations. A rotational stiffness for the foundation is estimated from the pseudo-static analysis and then compared to an acceptable minimum rotational stiffness provided by the turbine manufacturer. These minimum rotational stiffnesses are based on dynamic analysis of the tower and nacelle system with the foundation represented as linear springs. This approach provides a reasonable approach to the foundation design but does not accurately capture the true dynamic performance of the entire soil-foundation-tower-nacelle system. This becomes especially important for pier-type foundations, which are being more commonly used to support modern and future generations of larger turbines. Additionally, the dynamic performance of the foundation will vary as the adjacent soil undergoes a large number of loading cycles of varying strain magnitudes. In this study, the full turbine-tower-foundation-soil system was modeled using finite element methods. An advanced non-linear soil constitutive model and dynamic loading time histories were used to investigate changes in stiffness of the soil, and the possible impact on the dynamic response of the system. Results were compared to conventional design methodologies with the goal of reducing foundation capital costs while avoiding increases in O&M costs and which can lower the LCOE of wind energy.

Oct 1, 2022

By Joseph A. Mann

"Soil mixing is a proven solution for the construction of ground improvement adjacent to sensitive structures due to the use of computer controlled and monitored equipment. The precision to which geometry is controlled can often be the deciding factor for selection of soil mixing versus other means of ground improvement. Protection of existing structures and utilities requires careful planning, investigation, and may demand supplemental control measures. During planning, it is imperative that the process be fully developed by the project team to ensure proper control measures are budgeted; otherwise, the success and safety of a project can be jeopardized.This paper discusses case histories of soil mixing performed in close proximity to large, sensitive, and critical utilities, including foundation support for an existing earthen dam impounding a water reservoir in upstate NY, a buffer zone for a tunnel drop shaft at an operating wastewater treatment plant in Washington DC, and a containment system to protect a major water line along an interstate widening project in Baltimore, MD. The function of soil mixing as ground improvement varied; however, the selection and application of the technique versus other means of ground improvement was specific due to the controlled manner of construction with soil mixing. Through the three case studies, small diameter (3- ft [0.9 m]), large diameter (8-ft [2.4 m]), and mass mixing applications will be discussed. Furthermore, the case studies offer insight into how the geotechnical community in the Mid-Atlantic utilizes soil mixing technology for widely varying applications. Additional topics of discussion will be the design and construction of the ground improvement systems, procedures and execution of the work to protect existing structures, and the QA/QC methods, procedures, and results from the projects.INTRODUCTIONWet soil mixing, also known as the Deep Mixing Method, is a ground improvement technique that improves the characteristics of weak soils by mechanically mixing them with cementitious binder slurry. To construct columns, a powerful drill advances a mixing tool with radial mixing paddles located near the bottom of the drill string. The binder slurry is pumped through the drill string to the tool as it advances and additional soil mixing is achieved as the tool is withdrawn.Wet soil mixing is applicable in a wide range of soils. Soil mixing has been performed at depths more than 100 lf (30 m). Soils vary widely in their ability to be mixed, depending on the soil type, strength, water content, plasticity, stratigraphy, and texture. Almost any soil type, including organics, can be treated with certain soil mixing technologies, although they may require high binder contents and/or pretreatment to achieve the required results. In cases when the target soil is very soft, including some very weak clays and peats, 100% of the soil may require treatment. This complete coverage of soil mixing is referred to as mass mixing."

Jan 1, 2015

By Greg Nutson, Jeremy Butkovich, Bill Perkins, Hollie Ellis, Paul Bott

"Dynamic soil-structure interaction (DSSI) analyses are becoming more common in bridge designs, especially in seismically active areas. Because of its proximity to two active fault zones, the Evergreen Point west approach bridge replacement will be base isolated, and will be designed using DSSI. The project team completed two independent bridge designs to satisfy peer review requirements. The designs required substantial characterization of the soil dynamic behavior using both laboratory and in-situ testing. The analyses made use of earthquake time histories spectrally matched to conditional mean spectra. This led to reduced, and more realistic seismic demands on the structure, compared to conventional uniform hazard spectrum matching. The bridge analyses suggest that the preliminary bridge design is relatively conservative. This will allow the design team to potentially reduce shaft/column diameters and reinforcement. The design team estimates that the dynamic analysis design could represent a net savings of around $60 to $90 million compared to a conventional design.INTRODUCTIONThe Evergreen Point Bridge conveys State Route (SR) 520 2.6 miles (4.2 kilometers [km]) from Seattle to Medina across Lake Washington. The bridge is located in a seismically active area, and the Washington State Department of Transportation (WSDOT) has determined that the western half of the 1960s-era bridge (the “west approach”) is vulnerable to earthquake damage. WSDOT has begun preliminary design to replace the west approach bridge.The west approach extends about 6,100 feet (1,900 meters [m]) east from Seattle’s Montlake neighborhood, over Union Bay and Foster Island, then into Lake Washington proper (Figure 1). Approximately 5,600 feet (1,700 m) of the replacement bridge would be constructed over water. Subsurface conditions along the bridge alignment consist of 5 to 80 feet (2 to 24 m) of very soft peat and clay, over very dense/hard sand and clay. Multiple pile supported columns support the existing bridge. The new bridge would be supported by 8- to 10- foot-diameter (2.4 to 3.0 m) drilled shafts that extend about 50 feet (15 m) into the underlying very dense/hard soil. To reduce seismic demands on the bridge superstructure, WSDOT has decided to incorporate a base-isolation system into the bridge design."

Jan 1, 2017

By Timothy Nelson, Simon Burnworth

"The University of California’s new Berkeley Art Museum and Pacific Film Archive will showcase a collection of art and film in a facility that pairs an existing 1930s-era printing press facility with a new, architecturally unique auditorium wing. The centerpiece of this adaptive-reuse project is the existing 3- story art-deco Administrative Building, which will be integrated into the new museum and provide approximately 18,000 square feet of usable space. Degenkolb Engineers, as the shoring engineer of record, along with Condon Johnson & Associates Inc., the shoring contractor, worked together with general contractor Plant Construction Company to design and build a temporary structure to facilitate the complex retrofit, renovation, and expansion of the Admin Building. This paper will discuss the challenges faced by the design and construction team, the sustainable solutions implemented on the project, and the collaboration between teams to meet the unique constraints of the project and the site.INTRODUCTION AND PROJECT BACKGROUNDThe Berkeley Art Museum and Pacific Film Archive (BAMPFA), which currently resides in a 1970s-era post-modern concrete structure just south of the University of California Berkeley (UCB) campus, was in need of a new home after an engineering evaluation revealed that the building possessed seismic deficiencies. Pressed for space, the University looked within its portfolio of properties and identified the site of the former University Printing Press facility as the place to build BAMPFA’s new home."

Jan 1, 2017

By M. Melih Demirkan, Juan J. Gutierrez, Raghav Ramanathan

"As the capital of the United Arab Emirates (UAE), Abu Dhabi is one of the world’s fastest-developing cities. To sustain its significant growth rate, Abu Dhabi must surmount challenging engineering problems in the most efficient manner. One of the challenges facing Abu Dhabi is ground settlement caused by poor groundwater control practices in inherently difficult subsurface conditions. For construction projects in Abu Dhabi located near the Arabian Gulf, groundwater is frequently encountered and must be accounted for and addressed during design and construction. Abu Dhabi City CenterRecently, the Abu Dhabi government developed a geodatabase by digitizing, processing and qualifying an extensive amount of existing information (i.e., more than 26,000 borehole logs). Because of the evaluation and processing of the geodatabase, detailed maps of geotechnical and hydrogeological surface features were generated using 3D modeling. Ultimately, the geodatabase was used to develop risk maps indicating geohazards, such as sabhka (or salt flats), uncontrolled fill and cavities. This information identifies the location and extent of the areas vulnerable to surface subsidence. Dewatering can change pore water pressure, which, in turn, alters the effective vertical stress in a soil mass and can affect groundwater chemistry. Changes in pore water pressure and groundwater chemistry can significantly affect soil and rock. The potential effects of dewatering include:• Change in effective stresses and shear strengths in soils• Increase in seepage velocities and pressures• Erosion or transport of soil particles and piping• Settlement• Collapse of subsurface cavities or voids• Transport of groundwater containing contaminants• Dissolution of soluble materials, such as rock salt or gypsum"

Jan 1, 2017

By John P. Briand III, Douglas J. Aghjayan, Robert E. Fosse

This paper highlights the successful pile load testing program for the redevelopment of Pier One in East Boston, Massachusetts. Pier One is a 5.4-acre parcel on a dormant waterfront site used in the 1950s as a warehouse and distribution facility. The developer plans to re-use the existing 14-inch-diameter concrete-filled steel pipe piles to support four 5- to 7-story apartment buildings above a 2-story parking garage. A pile load testing program was developed to establish if the existing piles could support design loads of 240 kips for project financial feasibility and up to 300 kips for a significant reduction in future foundation costs. The Phase 1 program consisted of statnamic and dynamic load testing on two piles with two loading intervals (200 and 240 kips). Based upon the favorable results of the Phase 1 program, the Phase 2 program involved statnamic load testing on two piles and dynamic load testing on ten piles with three loading intervals (200, 240, and 300 kips). The Phase 2 program confirmed the favorable results which were applied across varying strata thicknesses and pile embedment depths. The average allowable capacity for the piles tested was greater than 300 kips with pile movement up to 0.3 inches.

By Jason Buenker, Molly Winston

Torque-installed piles are gaining popularity in Southern California as the go-to deep foundation element for small- to medium-capacity loads in urban environments. The torque-installed pile is a displacement- based screwed pipe pile with a closed-end conical tip welded to the bottom of the pipe. Torque-installed piles are most efficient in loose to medium dense soils with high liquefaction potential. Where used properly, torque-installed piles can be installed faster, require less clean-up, and create less onsite vibration/disturbance than other pile alternatives. However, torque-installed piles are not applicable in all soil conditions and care must be used to apply the pile effectively in the correct subsurface environment. This paper will review current Southern California state-of-the-practice for torque-installed pile design and construction, potential roadblocks to successful installation, and available capacities from load tests. INTRODUCTION Torque-installed piles are a type of full-displacement screwed pipe pile originally developed in Southern California circa 2001 by Substructure Support, Inc. The pile is unique for its proprietary closed-end conical tip shown in Fig. 1. The tip has a welded steel-helix plate and cutter teeth that allow the pile to be advanced efficiently under applied torque and down pressure (crowd). Since original development of the pile, several contractors or manufacturers have proposed similar proprietary screw-type piles with comparable conical tips. Pile installation is relatively quiet, vibration-free, does not generate spoils, and faster than comparable pile types. The pile was originally developed as an alternative to driven pile foundations and remains a critical substitute to driven foundations in urban environments. Torque-installed piles are conventionally specified as 12 ¾-inch outside diameter (OD) steel pipes with a ⅜-inch-thick wall, although larger sizes with alternative dimensions have been used outside Southern California. Pile installation lengths generally range from 30 to 50 feet but may reach 80 feet or greater where soil conditions permit. The pile is generally backfilled with concrete following installation to increase lateral pile stiffness and may incorporate rebar cages or other reinforcing steel to facilitate connections to structural elements. The pile is frequently specified using performance-based specifications that encourage contractor innovation and use of proprietary installation means and methods.

Jan 1, 2019

By Chetan D. Savani, Mike K. Muchard

The necessity to evaluate undocumented foundation lengths is essential in assessing the useable life, need for scour protection, retrofitting, or full reuse of existing bridge foundations. For this purpose, Parallel Seismic Testing (PST) has the best accuracy and is applicable to the widest range of foundation configurations used in bridge construction of any test method. Although not limited to bridges, PST case studies are presented involving two bridges. To preface the case study discussions, an overview of the PST method is given along with its results and analysis thereof. In one of the cases, we were afforded the rare opportunity to see the existing piles being extracted long after the PST testing program was completed. The resulting Class A prediction reaffirms the accuracy of the method. Versatility of the PST method is also exemplified in the two cases presented, where unique situations from complex foundation systems were overcome by analysis to provide successful results.

By Eric S. Lindquist

Two microtunnel access shafts were constructed using the Cutter Soil Mixing (CSM) method in the San Joaquin Delta region of California, east of San Francisco. Unlike conventional slurry walls and diaphragm walls that utilize concrete, soil mixing relies on blending the soils in situ with a cement slurry to create a soil-cement wall. Cutter Soil Mixing technology utilizes two sets of vertically mounted cutting wheels rotating about a horizontal axis to produce rectangular panels of treated soil. Overlapping of the soil mixed panels enabled the construction of two circular shafts. CSM panels were constructed to a depth of 29 m (95 ft) for the microtunnel jacking shaft and to a depth of 19 m (63 ft) for the microtunnel receiving shaft. The site presented several challenges, including the high depth of treatment, the variable nature of the alluvial soils, and the high water table. This paper describes the CSM technique and presents the design, construction, quality control measures and advantages of using this method for this project.

Jan 1, 2010

By Tai Luu, Michael McNicholas, James C. McIntyre

The Jersey City Municipal Utilities Authority (JCMUA), discovered that an existing sewer pipe had collapsed under the New Jersey Transit Conrail Railroad between Pine Street and Ash Street in Jersey City New Jersey. Immediate action was taken to abandon the pipe in place and install a new sanitary sewer. The borings showed 10-20 ft (3.04 m.- 6.09 m) of competent fill overlaying approximately 8 ft. (2.44 m.) of compressible peat and organics. Groundwater was at 8 ft (2.44 m) below ground level. The poor condition of the soils at subgrade could not withstand the extreme weight of the jacking machine or the thrust force required to push the casing from the launching pit to receiving pit. The support of excavation (SOE) would therefore not only need to retain the soil to allow the jacking equipment to reach subgrade at 14 ft (4.27m) below working grade, but also the back wall of the SOE would need to be sufficiently robust to function as the reaction block for jacking operations. The alignment and allowable tolerance for the jacked casing was minimal, therefore the performance of the SOE was extremely critical to the success of jacking operations. This paper will discuss in detail the design concepts that were developed and implemented by the team to overcome these obstacles. HISTORY The discovery of a collapsed section of an existing sanitary sewer led the Jersey City Municipal Utilities Authority to act on an emergency contract. The project design team was tasked with developing an abandonment plan for the broken pipe and installation of the new pipe through challenging geology. The new 180 ft.(54.96 m) long, 54-in. (1.37 m) . diameter sewer pipe was designed to be contained within a 72-in. (1.83 m) protective steel casing. The installation of the new sewer pipe would require a detailed understanding of the geology. The geotechnical subcontractor assembled a subsurface investigation report on November 2nd, 2017. It was quickly realized that the only way to replace the pipe was with a jacked pipe system since the large grade change and the Conrail Right of Way created no other alternative. Delaying or closing the railway was absolutely not an option as that particular railway served as the main heavy-haul route to and from Jersey City. It became apparent that a major obstacle to pipe jacking was the challenging geology present across and beneath the proposed sanitary sewer. The following challenges faced the design team prior to the installation of the replacement pipe:

Jan 1, 2019

By Tony P. Suckling

This paper describes an investigation into the bleeding behaviour of bentonite slurry observed on a trial diaphragm wall panel. The bleeding is thought to be due to the bentonite experiencing a chemical reaction leading to settlement of the solids within the fluid, possibly as a self-weight consolidation process. The trial panel was constructed in a busy airport environment where many different chemical products are used for de-icing the aeroplanes, runways, apron areas, vehicle access and pedestrian routes. The relationships between slurry contamination, bleeding, bentonite hydration time and filter loss behaviour were examined as no relevant published literature could be found. The results show that the amount of bleed strongly depends on both the degree of contamination and the hydration time. It is concluded that bentonite fluids should be allowed to sit in the storage tank for at least 24 hours after mixing, and that the filter loss test is a quick and effective method to determine the potential for bleeding of contaminated slurries.

Jan 1, 2011

By Alok Bhowmick

The most uncertain and challenging part of a bridge design and construction is the ‘Choice of foundation’. During the planning and conceptual design stage, it is extremely important to choose the right type of foundation. Wrong choice can lead to disaster for the project. This paper will present three interesting case studies of past bridge projects, to demonstrate how correct choice of foundation can help to meet the project commitments while the wrong choice of foundations can led to huge delay in project completion, leading to time and cost overrun.

Nov 1, 2022

By Challa Venkata Rami Reddy, Anindya Roy, G. R. Konni

This paper presents the results of pile lateral capacities obtained from both conventional design and fullscale pile lateral load tests. Conventional design using P-Y curve analysis is very commonly being used by designers; designers use well accepted software programs like Lpile and Allpile for analysis. However, these programs do not cover the soil models to simulate engineering behavior of marine carbonate sands; which generally have different engineering behavior than silica/quarts sands. In this study, the existing soil models for common sands have been used to assess pile lateral capacities and these results are compared with the results from full-scale instrumented pile lateral load tests performed in compacted marine carbonate sand fills of artificial island constructed for oil and gas facilities in Abu Dhabi. The objective of this study was to verify the applicability of the existing sand soil models for carbonate sands and also to verify the associated conservatism in the pile lateral capacities. This study shows that the actual pile lateral response is much stiffer than what was anticipated through the LPile analysis. Therefore, further research focus may be required to capture the engineering behavior of the marine carbonate sands to develop specific P-Y curves.

Sep 8, 2021

By Michael D. Justason

"In January 2009, long-time competitors, Anchor Shoring & Caissons Ltd. of Toronto and Bermingham Foundation Solutions of Hamilton, joined forces to tackle one of the Greater Toronto area’s largest deep foundation projects: the West Toronto Diamond Rail Grade Separation. The two companies formed the “West Diamond JV” and succeeded in winning the contract from the Canadian National Railways. This deep foundations work was the first and most significant part of the $300-million-plus rail grade separation project. A big part of the job turned out to be dealing with local government regulations and citizens’ concerns with noise and vibration.The project is approximately 10 km (6 mi) northwest of downtown Toronto in an area of mixed-zoning including light industrial, commercial and residential buildings. The area is commonly called the “The Junction,” because of the heavy rail- traffic. The “West Toronto Diamond” refers more specifically to the railway junction where the North-South tracks of Canadian National (CN) Railway meet at a level crossing with the East-West tracks of the Canadian Pacific (CP) Railway. The goal for this part of the project was to convert the West Toronto Diamond into a grade-separated junction by depressing the CN lines under the CP lines, thus allowing commuter rail carrier, called GO Transit, intercity carrier VIA Rail, and CN freight trains to pass through the new underpass.Dawn Tattle, president of Anchor Shoring & Caissons says, “not only is the site in a densely populated area adjacent to homes and businesses, the crews worked adjacent to active rail lines with numerous trains passing daily. During the 7-hour working day, approximately 60 trains passed through the site in very close proximity to working crews.” Safety was paramount. While trains were passing through the site, it was a railroad requirement that all equipment and men stop working. In addition, at those times, all personnel were required to stay 6 m (20 ft) from the tracks and were required to face the tracks. For the faster commuter trains, this work interruption could last as little as 2-3 minutes, while interruptions caused by the slower freight trains could last as long as 25 minutes. The most disruption to the site occurred during the morning commute between 7 to 9 a.m., so work did not really get underway until after that time. Once work finally commenced the race was on to finish as much as possible before the afternoon commute – hence the shortened work day. The amount of disruption caused by the trains was a big unknown faced by the JV going into the project, but crews adapted quickly to the very unusual work environment"

Jan 1, 2012

By Dominic Ammon, Mark Rothbauer, Paul Landers P. E.

Across the Potomac River from the location of the DFI47 Annual Conference (October 2022), in Alexandria, VA, two large permanent anchored walls with a decorative shotcrete face were recently constructed for the North Hill project, a new multi-family and townhome development. The project was executed with a design-build approach for the Fairfax County Redevelopment and Housing Authority with review by the Fairfax County Geotechnical Review Board. The project was constructed in highly variable Potomac group sediments that include high plasticity clay/silt terrace deposits overlying coarser grained materials. The soils were over consolidated and exhibited potential for slickensides from relief of horizontal stresses from past erosion. The wall system was designed to include deep soldier piles and permanent long strand anchors considering past slope instability in the area. As the construction progressed, problematic soil conditions and water issues required modifications to drilling methods. The two permanent walls spanned 800 and 1,000 feet long with a maximum height reaching 40 feet.

Oct 1, 2022

By Phil Wilkinson, Sam Whitaker

"The installation of large (XL) diameter monopiles offshore typically requires expensive and specialist plant, equipment and vessels. Due to the increasing size (weight, diameter and length) of the foundations, in order to mitigate installation risk, the use of large diameter drills is becoming an increasing requirement.Project developers often try to avoid drilling operations due to the time associated with the drilling process. This restricts projects in terms of location and it also overlooks the additional engineering benefits drilling can bring to monopile foundation design e.g. reduced foundation material and better fatigue design life.By comparing the lessons learned of three milestone overwater drilling projects; methods of maximising drill speed and decreasing drilling process time is established. Particular emphasis is put on pile internal relief drilling in a process known as Drive-Drill-Drive (DDD).The milestone overwater drilling projects are North Hoyle Offshore Wind Farm (OWF) (2003); Flamanville EPR cooling water outlet shaft (2008); and Gwynt-y-Mor OWF (2014).By evaluating the effect of foundation pile diameter on drilling process times, example foundation installation costs are derived and used to show that incorporating drilling as part of a process may not be cost prohibitive to projectsContinued advances in drill technology, and drilling rates of penetration, combined with an integrated approach to foundation design, challenge whether hammering only is always the optimal solution for XL monopile installation."

Jan 1, 2017

By Ramin Motamed, Farshid Ghazavi, Joseph A. W. Toth

"Post-disaster reconnaissance of areas affected by earthquakes has documented extensive damage to buildings with shallow foundations located in liquefaction-prone areas. Currently, estimation of liquefaction settlement is based on empirical correlations that evaluate settlement in the free-field environment and are based on one-dimensional consolidation. However, observations have shown that liquefaction settlement under buildings can be considerably greater. This research is based on a series of 1- g shake table experiments using a transparent soil box to reproduce liquefaction-induced building settlement. Building settlements were evaluated using a scaled model of a building foundation representing a 1-2 story building. Comprehensive parametric study was carried out to establish the effects of several parameters on free-field and building settlements such as building width and thickness of liquefiable soil layer. The experiments utilized accelerometers and pore-water pressure sensors to monitor ground accelerations and buildup of pore-water pressures in both the free-field and model building footprint. Results of these experiments are compared to available centrifuge tests and field observations and conclusions are drawn with respect to the potential scaling effects. Lastly, this paper discusses the feasibility of installing helical piles as a mitigation strategy to reduce the building settlements by presenting some of the exploratory experimental data obtained from this series of 1-g shake table tests.INTRODUCTIONThe 2010-2011 Canterbury earthquake sequence and the 2011 Great Tohoku earthquake are some of the most recent examples where large numbers of low-story structures sustained damage resulting from liquefaction-induced settlements. This damage has commonly been observed in residential and commercial areas developed over loose, unconsolidated and saturated coarse grained soils resulting from both natural and man-made deposits. Damages incurred from the 2010-2011 Canterbury earthquake sequence occurred in the largely unconsolidated fluvial environment bordering the Avon River in Christchurch (Henderson 2013). Similar damage was also incurred during the 2011 Great Tohoku earthquake where liquefaction of soils occurred in both young alluvial deposits and fill materials (Ashford et al. 2011). Figure 1 presents typical modes of failure to structures resulting from the effects of liquefaction. Current practices in evaluation of liquefaction settlement rely on empirical correlations (Tokimatsu et al. 1987; Ishihara et al. 1992) developed for liquefiable soils in the freefield environment (Dashti et al. 2010a). However, recent observations of the performance of foundations suggest that settlement of rigid shallow foundations in liquefiable soils are commonly greater than those predicted in the free-field. Therefore, new correlations should be developed to better predict the degree of settlement of shallow foundations in liquefiable soils. Current research is beginning to focus on the mechanisms of settlement during liquefaction in regards to confining stress, pore-water pressure and shear stress induced from foundations (Dashti et al. 2010b)."

Jan 1, 2016

By Arunsiva R., Sivaranan S., Venugopal B., Kumaran M.

Being a rapidly developing country, India is undergoing a massive infrastructure phase change remarkably. The construction industry is already set to boom, but the time and space constraints necessitate the employment of heavy plants and machinery to take the foundations deeper than ever. Operating such machinery on soft or poor ground conditions without a good working platform leads to uncertainties with massive loss of men and machinery. Plenty of such cases can be observed on construction sites across the globe. Unfortunately, forming a temporary working platform is given least to no importance in the construction industry, particularly ground engineering. This glitch can only be addressed through standard guidelines or codal recommendations on designing and implementing temporary working platforms issued by regulatory bodies. The present paper highlights the importance of providing the working platform, existing design method for working platforms such as TWf 2019:02 of Temporary Works forum, Building Research Establishment BR470 and a brief discussion on the design and construction of the geosynthetic reinforced working platform with a case study is also included. A pitch has been made on the importance of Indian codes/guidelines for the design and construction of temporary working platforms. These guidelines will ensure the safety of the men and heavy machinery and, in addition, increase the productivity of foundation construction irrespective of weather conditions and also become part of the regular construction scope.

Sep 1, 2022

By Arash Saeidi-Rashk-Olia, Dunja Peric

Energy piles are gaining increased popularity due to a growing demand for clean energy. To further advance the understanding of soil-structure interaction in energy piles, recently-derived analytical solutions have been implemented to investigate the impact of stratigraphy on the soil-structure interaction. This was accomplished by comparing the measured and predicted head displacements, axial strains and stresses in an energy pile embedded in the actual homogeneous and layered soil profiles, as well as into synthetic homogeneous soil profiles. The analytical solutions for homogeneous soil profile captured the smooth experimentally observed response versus depth very well. In the case of a layered soil profile, the corresponding analytical model was capable of capturing nuances in trends of axial stress and strain versus depth at the interface of different layers. The analytical predictions for the layered profile appear to be slightly less accurate than for the homogenous profile. The experimental data obtained from the layered profile appear to be a bit more scattered than those from the homogeneous profile. In the former case, the interplay of the individual soil layers with the pile occurs while maintaining the continuity of the pile stress and displacement at the interface of different layers. The response throughout each layer of the layered profile is quantitatively different than the corresponding homogeneous response. Nevertheless, qualitatively the response throughout each layer of the layered profile is similar to the response of the pile embedded in the corresponding homogeneous layer.

Sep 8, 2021