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By Ali Ebrahimi, Meena L. Viswanath, John F. Beech, Mustafa B. Erten, Ming Zhu

"Excessive deformation of a cantilever sheetpile wall can occur due to dredging, excavation, backfilling, or long-term creep behavior of soil. A buttressing berm constructed in front of the wall can be considered as a mitigation technique to prevent or decrease the deformation by increasing the passive earth pressure and thus improving the wall stability. The effect of the buttressing berm on the stability and deformation of a sheetpile depends on the berm geometry (i.e., the thickness/depth and the width) as well as the properties of the sheetpile and the adjacent soils. A parametric study was conducted using a conventional limit equilibrium method. Design charts were prepared to evaluate the effect of a buttressing berm and the soil friction angle on the wall stability and deformation. These charts can be used as a tool by geotechnical engineers to make a quick estimate of the required size of a buttressing berm in case of calculated or unexpected excessive deformation of a sheetpile. An analysis of the effect of a buttressing berm on the stresses and deformation of a sheetpile was also compared with the results from finite element analysis. The results of this comparison are discussed.INTRODUCTIONCantilever sheetpile walls are commonly used to support excavations. Sheetpiles are hot rolled or cold formed sections of steel made to interlock with adjacent sections to form a continuous structure providing lateral support. Sheetpile walls can be cantilever walls or anchored with tiebacks. To construct a cantilever sheetpile wall, sheetpiles are driven by pile drivers or vibrated in to a design depth sufficiently below the depth of excavation. Excavation can then proceed in front of the sheetpile wall, which resists the earth pressure loading from behind the wall. The design depth and geometry of the sheetpile wall depend on the soil conditions, the depth of excavation, and the tolerable deformation. In certain cases, when a small buttress of soil can be left immediately adjacent to the sheetpile wall, the required depth or geometry of the sheetpile wall can be reduced or adjusted, which can significantly decrease the cost of procuring and installing the wall. Such a buttress can also serve as a short-term or long-term remedy in case of observed excessive deformation in a constructed wall. Traditional methods of analyzing the stability of a sheetpile wall do not account for the passive pressure effects of this small buttress. In this paper, a parametric study was performed for a variety of soil types and wall and buttress geometries by implementing traditional limit equilibrium methods in commercial software and design charts were created illustrating the effect of a buttressing berm on sheetpile deflection. Selected cases were then modeled in a finite element software to compare the results with the traditional limit equilibrium method. The resulting design charts can be used as a tool by geotechnical engineers looking to reduce the design geometry of a sheetpile wall or address observed excessive deformation in a constructed sheetpile wall."

Jan 1, 2016

By Mohsen Elsayed, Amr Sallam, Ahmad Mohamed, Xuebing Zheng, Mohamed Alrowaimi

The foundation is an essential component of the wind turbine that ensures continued operation under stable and safe conditions. Both shallow and deep foundations are utilized to support wind turbines including gravity spread foundation, anchor foundation, pier or drilled shaft foundation and pile and pile cap foundations. Conventional methods were typically utilized to design the wind turbine foundations. With the advances in numerical modeling in the geotechnical field, foundation designers may utilize numerical analysis to design wind turbine foundations. Geotechnical numerical packages allow modeling structural components and soil-structure interaction that is usually neglected in conventional methods. Furthermore, the subsoil conditions, geometries, stress-strain behavior, boundary conditions and load staging can be modeled, minimizing the assumptions and generalization. This results in better understanding of the stress strain behavior of the foundation leading to optimized foundation designs. This paper includes a brief review of current foundations used to support wind turbines with an emphasis on post tensioned single pier foundations. The current conventional foundation design methodologies and state-of-the-art foundation design utilizing numerical modeling of the single pier foundation will be discussed. Two case histories where the single pier foundation, designed using numerical modeling, were utilized to support the wind turbines will be presented. INTRODUCTION The foundation is an essential component of every wind turbine that ensures continued operation under stable and safe conditions. Turbine manufacturers provides load specifications for designers to be utilized for wind turbine foundations design. Loads include bending moments, torsional moments, lateral forces and vertical forces in both operational and extreme wind conditions. Essential specifications under seismic conditions might also be provided in seismic prone areas. Turbine manufacturers also include foundation design criteria including minimum rotational stiffness, minimum horizontal stiffness, maximum allowed inclination and maximum allowed lateral movement under both operational and extreme loads. Geotechnical explorations and evaluations are typically performed at early stages of the wind development projects. The field explorations usually include Standard Penetration Test (SPT) borings, Cone Penetration Test (CPT) Soundings, geophysical surveys, and laboratory tests to define soils stratification system and soil strength and compressibility characteristics. The most critical soil parameters for turbine foundation design are shear strength parameters (cohesion and friction), shear modulus, Poisson’s ratio, and unit weight. The depth to the groundwater table is also a crucial parameter in design. Advanced field explorations techniques such as Dilatometer Tests and Pressuremeter Tests may also be utilized. Laboratory tests for foundation design typically include index parameters, consolidation and triaxial tests.

Jan 1, 2019

By Satyajit Vaidya, Rudolph Frizzi, Quadri Owokoniran

"This paper presents a case history in the design and construction of high-capacity drilled shafts for the iconic New York Wheel presently being constructed along the St. George area waterfront in northern Staten Island, New York. Although the site is located in an area that offers views of the Statue of Liberty, the Manhattan skyline, and New York Harbor, the variable and challenging subsurface conditions at the site and the structural loading requirements for Wheel erection and service conditions presented geotechnical design and construction challenges. The paper focuses on site and subsurface conditions, drilled shaft design and construction details, results of Osterberg-cell and lateral load testing, and load test data analysis and evaluation.PROJECT DESCRIPTIONThe proposed 630-foot (190 m) -tall New York Wheel (the Wheel) is projected to be one of the tallest observation wheels in the world. Upon completion, the Wheel will be capable of carrying over 1,400 passengers in its 36 capsules. The Wheel site is located along New York Harbor offering views of the Statue of Liberty, the Manhattan skyline, and the New York Harbor; see Fig. 1. The Wheel structure is sited along the waterfront, and served by a 3-story terminal located south of the Wheel in the eastern portion of the site and having a footprint area of about 34,250 sq-ft (3,180 sq-m). A 4-story parking Garage, with a footprint of about 112,840 sq-ft (10,480 sqm), is to be constructed south of the Wheel in the central and western portions of the site.SITE AND SUBSURFACE CONDITIONSThe site’s close proximity to the New York Harbor presented geotechnical challenges because the site is located in an area that was once beyond the historic shoreline of Staten Island. The site is an about 350,000-sq-ft (32,500-sq-m) parcel generally bounded by the Richmond County Bank Ballpark to the southeast, the 9-11 Memorial to the east, Bank Street to the north and northeast, and Richmond Terrace and an associated retaining wall to the southwest and south. A 50-ft (15-m) -wide New York City Transit Easement, with an active on-grade service area and tracks, is located in the southern portion of the site. See Fig. 2 for site location and approximate location of the Wheel foundation footprint."

Jan 1, 2016

By A. Ortigão, M. Felix, E. Falk, T. Koehler

"Ground improvement techniques such as vibro-replacement or deep soil mixing are fairly young products in the Brazilian geotechnical market. Soft soils in this country are deep, very soft, have low sensitivity and are challenging. In general, ground improvement techniques are increasingly selected as more costefficient and flexible solutions on infrastructure projects compared to the conventionall technologies such as piled embankments, wickdrains with surcharge or jet-grouting. The geotechnical challenge expansion project for the Porto Alegre Airport, South Brazil, involved a taxiway area of five ha of 8 to 10 m of soft clay deposit. The deep soil mixing (DSM) technique was selected as a cost-effective solution to reduce settlements. As part of the design, an extensive soil investigation programme includ ing laboratory and field trials was carried out to define the most economical slurry-recipe, DSM installation patterns and quality control specs. This paper gives details of the field and laboratory trials and present results.INTRODUCTIONThe International Airport of Porto Alegre in the state of Rio Grande do Sul in Brazil is located in an area with extensive sediments near to Guaíba Bay. During the different construction phases of the airport over the last decades, the soft clay deposits have been a challenge for the local geotechnical community as well as for the specialized contractors (Schnaid et al, 2001). As part of the most recent expansion scheme, a cargo-terminal with a five ha airplane tarmac area will be constructed."

Jan 1, 2015

By Venugopal B, M Kumaran, Thomas John, Vetriselvan A

The initial pile load tests are conducted to ensure the geotechnical capacity of the pile in a particular site condition. Normally kentledge method is adopted for the compression pile load tests. In this method the entire kentledge load is loaded above secondary beams which are supported by concrete blocks above the Natural Ground Level. So, it is important to ensure the SBC (for shear and settlement) of the natural ground. In one of our projects initially it was decided to go with kentledge system for initial compression load test on 56m long 1200mm diameter BCIS pile. The test load and total kentledge load were 2160t and 2700t, respectively. The soil strata mainly consisted of clay with low SPT N value and water table almost at ground level. It was suggested to replace top soil using Granular Sub-base (GSB) with good compaction in order to avoid excessive settlement of concrete blocks placed to support the kentledge weight. When the kentledge loading started, even before reaching 10% of total kentledge load, excessive settlement on the GSB layer was observed. This paper describes the problems faced during normal kentledge method and how it was overcome using the liner pile system for initial compression load tests in this particular site condition for higher test load.

Nov 1, 2022

By Xavier Pita, Alexandre Pinto, António Cristovão, Rui Tomásio

"The cutter soil mixing technology was been applied in Portugal since the last seven years. The aim of this paper is to present the main design and execution criteria, related with both the cofferdam and foundations solutions, using soil-cement panels, reinforced with steel profiles, at the new Leixões Cruise Terminal, located at the Leixões Port, in Portugal. The Terminal building was built with one basement on a marine environment, over very difficult geological and geotechnical conditions, which demanded the use of some unusual and integrated geotechnical solutions. It is also pointed out the importance of the QC/QA, as well as the technical, economic and environmental advantages of the cutter soil mixing technique, comparing with same more conventional solutions.1 INTRODUCTIONThe construction of the new Cruise Terminal at Leixões, main gate of the Atlantic Ocean to the North of Portugal and Spain, as a consequence to the constant increase of the cruise traffic, was a challenge from both the geotechnical and structural point of views, mainly due to very difficult and unusual conditions, ranging from the geological and geotechnical scenario to the existent and under operation Leixões Port infrastructures, mainly the South break water, as well as the existent cruising boarding deck (Figure 1).According to the Terminal Project it was necessary to build one basement below the water table level, including several earth retaining structures in order to allow the excavation works on dry conditions leading to a global cofferdam effect. For this purpose soil - cement panels, using CSM technology, reinforced with steel profiles, micropiles (both for foundation and cut off effect) and the existent sheet piles were used. Also pointed out are the adopted special foundations of a very complex structure, including bored piles and micropiles (Figure 1)."

Jan 1, 2015

By Unnikrishnan Nair, Sandeep S. Nikam, Sanjay D. Patil, Prabir C. Basu

"Mumbai Metropolitan Region Development Authority (MMRDA) entrusted to implement Monorail Systems in various parts of Mumbai Metropolitan Region (MMR) with the objective to supplement the present transport system in MMR. The stretch of Monorail is starting from Sant Gadge Maharaj Chowk (SGMC) and extending up to Chembur Railway Station, divided into 2 phases. Construction of Phase 1 (Chembur to Wadala Depot) is complete and Phase 2 (Wadala Depot to SGMC) is under construction.Monorail runs on prestressed girder (guide beam) of span ranging from 20m to 28m supported on pier founded upon group of end bearing piles embedded in rock, pile group ranging from 2-4 piles of diameter 1000mm each.For the purpose of site characterization, geo-technical investigations were carried out along the alignment of Monorail system as mentioned above. These investigations included field and laboratory tests. The subsurface strata mainly consist of silty sand, gravel, underlain by marine clay extending up to stronger basalt rock with volcanic breccia. Overburden consisting of mainly marine clay ranging from 5.5m to 11m at all locations within the influence zone of settlement.The existing rigid pavement along of Sion-Koliwada and Anik-Wadala were constructed about 5 years prior to the construction of Monorail piers. Before laying the rigid pavement, to improve the geotechnical strength of subsoil (mainly marine clay), ground improvement using stone columns was undertaken by MMRDA. In light of limited right of way, the Monorail piers have been constructed in the median portion of the road. The line became operational on February 2014, in few months it was noticed that, in the vicinity of the Monorail piers, along Sion-Koliwada link and Anik-Wadala link, the Road Pavement Quality Concrete (PQC) panels adjacent to the Monorail piers started showing distress in form of nonuniform settlement of the concrete panels.Effect of pile foundation on pavements/PQC slab distress and possible causes of distress were investigated. Initially the distress was thought to be upheaval of monorail pier cap, but further investigations revealed the same to be soil settlement occurring over time. This paper describes the investigation carried out for identifying the cause of this settlement."

Jan 1, 2015

By Sanjay Gupta, Sorabh Gupta, Ravi Sundaram, Abraham Varghese

"Geotechnical investigation for the Kochi Metro revealed a critical section of the Viaduct near Ernakulam Junction Railway Station. Four piers, located over a 220 m stretch, were passing through an area with substantial thickness of soft clay. The scope of the geotechnical investigation included two boreholes and a static cone penetration test at each pier location. In the boreholes, field vane shear test was conducted at different depths in addition to the routine SPT. The design of heavily loaded piles in such strata is a challenge due to the liquefaction of the shallow sands and negative skin friction / down-drag in the soft under-consolidated clay. Bored cast-in-situ piles of 1500 mm diameter extending to 50-60 m depth were used to carry 500-600 tonnes load.INTRODUCTIONThe first phase of the rapid transit system at Kochi, Kerala (See Fig. 1) whose elevated route spans from Aluva to Thripunithura covers a total distance of about 25 kilometers. One of the more critical sections of the viaduct exists near the Ernakulam Junction Railway station where the alignment takes a sharp curve to move towards Vyttila, crossing the railway tracks and running partially over the approach of South over-bridge.In this section, four piers located on either side of the railway tracks near the Route Relay Cabin of Ernakulam Junction Railway Station pass through an area with substantial thickness of soft underconsolidated clay.The alignment is geotechincally challenging due to the presence of loose liquefiable sand and soft underconsolidated and sensitive clay.Initial investigations by the owner based on limited boreholes only yielded conservative and inconclusive pile capacities. For a thorough understanding of the soil behaviour, a detailed geotechnical investigation was carried out to assess the engineering behaviour of the soil strata.The scope of the geotechnical investigation included two boreholes and a static cone penetration test at each pier location. In the boreholes, field vane shear tests were conducted at different depths in addition to the routine SPT."

Jan 1, 2015

By Yazen Khasawneh, Osvaldo P. M. Vitali, John E. Agee, Mohammad Nassim

A 3D FEM modeling of a ground improvement solution for an ice rink slab with stringent differential settlement limits is presented. Due to the complexity of the geotechnical conditions and strict deformation requirements, a structural slab supported by micropiles was initially proposed. However, this solution was costly and alternative solutions using ground improvement techniques were investigated. The proposed slab is supported directly on rock at one end and on approximately 45-ft deep cohesive soils on the other end. The numerical simulations show that differential settlement would be larger than allowable, if the ice rink slab is supported directly on the existing subgrade. The addition of the ground improvement scheme with compaction grouting demonstrated that the anticipated differential settlements are reduced significantly and would become less than the allowable magnitude. This study demonstrates that the use of numerical simulations to study complex loading and geological conditions will help to optimize designs and may result on significant cost savings.

Sep 8, 2021

By Steve Davidow, Scott Tunison

As the demand for electric power grows and generation facilities are constructed in more remote areas, the industry faces an increasing number of foundation construction challenges. The importance of quality geotechnical information prior to construction is accentuated by the linear nature of the projects and the potential for drastic changes from one end to the other, but is often difficult or unfeasible to obtain. Alignments are crossing remote, rugged and/or environmentally protected terrain, and completing a comprehensive geotechnical program is made challenging from an access or economic standpoint, or both. In these situations, the industry needs a flexible foundation alternative. This paper will present micropiles as that alternative and demonstrate how the implementation of micropile foundations mitigated these challenges on the Koolau-Wailupe 46 kV Circuits in Oahu, Hawaii, which involved rugged, steep slopes and helicopter construction methods. It will detail the selection of micropiles over other foundation options, micropile and steel pile cap design methodologies, foundation construction, and quality control. Special attention will be given to the unique geology in the area, and why precise identification of saprolite and basalt layers was integral to the successful performance of the foundations. The intention is to communicate the benefits of a flexible solution based on continuous collaboration between design and construction.

By Arpana P. Sabu, Themis Vaxevanis, Sissy Nikolaou, Guillermo Diaz-Fanas

Geo-failures from extreme events (landslides, wild fires, earthquakes, floods, etc.) have increased exponentially in recent years around the world and within the USA. When catastrophic failures occur, they usually involve hundreds of fatalities especially in cases of unexpected triggering events, such as large intensity earthquakes or heavy flash floods. Protective actions against identified potential geohazards can mitigate the associated risks and the future occurrences and prevent these occurrences from becoming disasters, targeting the essence of resilience in geotechnical engineering. Imaging and other virtual design and construction tools can be used to identify weaknesses that trigger geohazards and can, in combination with numerical simulations, guide decision making. In spatially distributed problems, 3D visualization and LiDAR-type of technologies are essential in providing geotechnical engineers a deeper understanding of precarious soil zones and support finding appropriate solutions. This paper will present the value of using virtual design and construction technologies though the case study of the Iztapalapa suburb of Mexico, about 20 km southeast of Mexico City. Iztapalapa was developed within irregular topography and has a long history of severe soil subsidence. Following the 2017 Puebla-Morelos earthquake, the town experienced large settlements resulting in extensive damage to the already frail buildings and unregulated infrastructure. The soil subsidence was visualized by mapping available historic and geotechnical data. The visualization helped to identify areas where additional investigations were needed. Additionally, this paper presents a case study of a series of landslides from the 2016 Mw7.8 Muisne Ecuador Earthquake, which demonstrates the advantages of using novel technologies to collect data and create cloud datasets from drones and digital photos to understand and evaluate geo-vulnerabilities in anticipation of an extreme event and during rapid reconnaissance to plan for long-term instrumentation, which can enhance geo-disaster prevention and overall community resilience. INTRODUCTION Iztapalapa is a southeastern borough of Mexico City (CDMX) located within the Mexico Basin (Figure 1). This borough is a densely populated area of CDMX with a total of 1.8 million inhabitants, and has a third of its population living in poverty (Gonzalez-Hernandez et al., 2015) with limited to no access to clean drinking water. Iztapalapa also suffers from high rates of crime, drug trafficking, sex trade and illegal buildings. As the population continues to grow, the already non-regulated and fatigued infrastructure is unable to meet the community needs, especially during and after natural hazard occurrences. The region of CDMX is one of the world’s most seismically active regions that is also exposed to other geo-hazards such as floods, volcanic eruptions, and continuous settlement due to water pumping that has reached 11 meters over the past 100 years (Nikolaou et al, 2019). While the soil subsidence alone has caused significant infrastructure damage in Iztapalapa and throughout the rest of the city, recent earthquakes have also contributed to those damages.

Jan 1, 2019

By Patrick J. Hannigan, Seth Robertson, Frank Rausche, Rozbeh B. Moghaddam

The Top-Loaded Bi-Directional Test (“TLBT”) and the conventional Bi-Directional Load Test (“BDLT”) are full-scale load tests where loads are applied bi-directionally to the foundation element. The BDLT uses an embedded loading source consisting of a jack assembly with one or multiple hydraulic jacks located between two steel bearing plates. As the jack(s) within the jack assembly is/are pressurized, the plates receive the load from the jack(s) and transfer these loads to the foundation element. In the case of the TLBT, the loads are also applied bi-directionally to the foundation element. However, in the TLBT case, the loading source is located above the foundation head. With the TLBT’s non-embedded and reusable load assembly, the loads are applied to the foundation using the steel shaft bearing and base bearing plates cast within the foundation. These plates are connected to the load assembly at the foundation head via Grade 75 or Grade 150, threaded, steel bars. This paper presents comparison results from a full-scale load test performed by both bi-directional load testing methods on adjacent test shafts. Details regarding subsurface conditions as well as test shaft construction and installation are included for the comparison tests. Test results and corresponding analyses are presented and discussed in detail.

Sep 8, 2021

By Clarissa Aguiar, Seok hyeon Chai, Thamer Yacoub, Sina Javankhoshdel

Sheet piles are used as an excavation support for soil retention. They are interlocked systems to form a wall for earth support along with anchors to provide an extra lateral support in excavations. The earth pressure against a sheet pile structure is not unique for each soil, but rather a function of soil-structure system. Movements of the structure with respect to the soil are primary factor in developing the pressure and thus the problem becomes indeterminate. In order to model a sheet pile wall for the analysis, structural element/interface can be used for the sheet pile. However, the use of the structural element with soil model alone is insufficient to simulate this soil-structure system as it fails to capture the slip condition between the sheet pile and the retained soil. In order to capture this slip condition, an interactive element can be used between sheet pile and soil to allow slip to occur. There have been many case studies where this method was used to analyze the response of the retained soil. Numerical studies have shown a good agreement with experimental results, but this stiffness is often not a well-known parameter, due to its complexity in nature of interactive behavior between soil and sheet pile walls. Also, many case studies are carried out with twodimensional analysis of the foundation, where three-dimensional analysis may be more suitable in some practical applications. In this paper, the interactive behavior of the element between sheet pile and soil is investigated with case studies for staged excavation using sheet piles and anchors. Then, investigation of a three-dimensional model is carried out by comparing with two-dimensional analysis.

By Maurizio Siepi, Paul van Horn, John Coupland, Julian Crawley

"TTMJ is the acronym for the Slurry (Diaphragm) Wall Tension Track Milled Joint currently in development as part of the European Union's innovative and far-reaching Horizon 2020 initiative (FTI Pilot-2015-1 720579). The TTMJ Project has been specifically set up to deliver this versatile new step-forward in Slurry Wall technology. The TTMJ System is protected by patent in Europe and the USA, and is currently under development by a consortium comprising Trevi SpA (Italy), Arup (Netherlands) and CCMJ Systems (UK). The principles of the TTMJ System together with the installation process are herein described in general terms. The system is still under development with field trials scheduled for early 2018, so some of the detail will not be disclosed at this stage. It is the intention of the Authors that the results of these field trials and a more complete description of the System will be presented in a paper we intend to submit for the DFI/EFFC International Conference on Deep Foundations and Ground Improvement to be held in Rome, Italy in June 2018. The final section of this paper explains how the TTMJ system can be applied to a common application of slurry wall construction; deep circular or multi-cell shafts. The system can be used to construct shafts more easily and at less cost than current methods. It also allows shafts with smaller internal dimensions to be constructed than is currently practical.INTRODUCTIONCCMJ Systems (UK) realised that an innovative new approach to forming joints in both Slurry (Diaphragm) Walls and Secant Pile Walls would provide greatly improved joint integrity to greater depths, to the overallbenefit of retaining wall quality, across the world-wide foundations industry.In particular this new system is designed to:??Increase the effective depth range of Slurry Walls (especially walls excavated by grab) and Secant Walls??Remove the requirement for Stop-ends or Joint Formers??Allow for a Shear Key at the joint??Allow for a Water Stop to be installed at the joint??Permit Continuous Reinforcement across the joint??Optimise Reinforcement Density and hence Concrete Flow??Facilitate joints in corner panels eliminating the need for “L” shaped cages and reducing largesingle-pour concrete volumes and slurry storage capacity requirements.??Enable the construction of smaller-dimensioned square and circular deep shafts (especially useful for city-centre sites) than is possible with current methods.CCMJ Systems approached other industry specialists with a view to forming a development team to explore the possibilities for this new technique."

Jan 1, 2017

By Brenton Cook, Daniel Mageau, Larry Applegate, Aaron McCain

"Ground freezing was successfully used to create an impermeable barrier wall along 3,000 feet of the downtown Seattle waterfront as part of the Seattle Seawall Replacement Project. This $360 million re-development involved removing the original 1930-era seawall and replacing it with a new, seismically resistant concrete wall supported on fill soil improved by jet-grout. The replacement wall was one of the largest construction projects in the state of Washington at the time. Ground freezing is typically used as both a structural shoring wall and groundwater cutoff. However, at this project it was used primarily as a cutoff wall to stop groundwater seepage into the 16-foot deep excavation from the landside areas.The project was divided into ten boxes (sections), each typically 200 to 600 feet in length. Only a few boxes were under construction at one time to reduce the impact on tourist-dependent local businesses. Soil conditions in the freeze zone consisted of sand, gravel and silt fill with abundant wood and debris. Tidally influenced groundwater, much of it contaminated, was difficult and expensive to control using wells during initial stages of construction. For all subsequent stages, a frozen soil wall extending to about 35 feet in depth was used to stop groundwater seepage into the excavation. An additional benefit of ground freezing included elimination of potential settlement beneath nearby buildings, utilities, and the Alaskan Way Viaduct that would likely have occurred with the use of conventional dewatering wells. The frozen soil wall crossed more than 130 buried utility locations (including water, sewer, storm, electrical, fiber optic, phone, gas, steam) with no damage. The frozen soil wall was very successful and limited groundwater influx from the landside to the seawall excavation to a negligible amount so that pumping, storage and treatment of contaminated groundwater was essentially eliminated."

Jan 1, 2016

By Terry Eldridge, Keith MacKay, David Siddle, Luke Moger

On August 4th, 2014, a breach occurred in the Perimeter Embankment of the Tailings Storage Facility (TSF) located at the Mount Polley Mine, releasing approximately 10.6 million m3 of supernatant water, 7.3 million m3 of tailings solids, 6.5 million m3 of tailings interstitial water and 0.6 million m3of construction materials. A Temporary Upstream Rockfill Berm was constructed between August 2014 and February 2015 within the area of the tailings dam failure in order to retain the remaining tailings solids during the low flows of the winter season. The Temporary Upstream Rockfill Berm was constructed as part of the initial response phase, with the primary objective to abate the flow of tailings into the receiving environment. A secondary objective of its construction was facilitating the required investigation works downstream of the tailings dam failure. The selection of the coarse grained material used in the construction of the Temporary Upstream Rockfill Berm was based on the availability of the material (timeliness of construction) and the non-water retaining design of this initial response phase. Consequently, an alternative method was required in order to prevent further loss of mine-affected water and tailings from the TSF, as well as to provide short-term contingency water storage, during high flow conditions expected in late spring. Golder Associates Ltd. designed the 2015 Freshet Management Embankment, a deep mixing cut-off wall, to meet these site requirements, which was constructed by Mount Polley Mining Corporation and Golder Construction Inc. between December 2015 and April 2015. The works included 132 soil cement panels constructed to depths of up to 27 meters. This aspect of the works was completed using an RG25S Bauer CSM rig on a 24 hour per day, 7 day per week schedule. The cut-off wall specifications included a target unconfined compressional strength (UCS) of between 1 and 2 MPa, a maximum hydraulic conductivity of 1x10-6 cm/s, and a ductility to enable the soil cement to undergo a minimum of 5% strain without a reduction in strength or increase in hydraulic conductivity. In order to control and assure the quality of the soil cement, 2553 wet grab specimens were retrieved from the fresh soil cement panels using a project-developed sampler. Four of the soil cement panels were cored with a mud-rotary drill rig and optical and acoustic televiewers were placed into the boreholes in order to log several relevant parameters, including image, texture, relative hardness, borehole-shape, and temperature.

Jan 1, 2016

By George Gazetas, Sissy Nikolaou, Fani Gelagoti, Irene Georgiou, Rallis Kourkoulis

"The need to shift geotechnical design from a “factor of safety” to a “performance based” design (PBD) approach has increased rapidly in the past years following examples from structural engineering. PBD supports sustainable engineered systems that target project-specific geotechnical behavior objectives and results in more rational and, in most cases, less conservative solutions. Resiliency, efficiency, risk optimization, and cost-effectiveness are key components of this approach. For design of retaining walls, the concept of mechanically stabilized earth (MSE) systems combines these attributes, while being environmentally friendly and adaptive to variable construction conditions. Natural hazards, such as earthquakes, may drive the design of MSE systems whose reliability depends on their performance under extreme events. In this paper, the authors compare the seismic response of an MSE steel-reinforced vs. concrete-reinforced retaining wall. The MSE system is composed of a grid of longitudinal and transverse ribs which internally enhances the capacity of the soil backfill. Results of fully non-linear twodimensional (2-D) numerical finite element analyses using two commercial programs with emphasis on the interface conditions are presented. The pull-out resistance of the grid used in the numerical simulation was evaluated from actual pull-out experiments. The results demonstrate a superior performance of the MSE system as compared to the concrete one, especially when subjected to strong seismic excitations.INTRODUCTIONThe idea of performance-based geotechnical engineering is not new, and has been evolving as our perception for ‘good’ performance has also evolved (Kramer, 2008). In early practice, the only criterion for achieving good performance was to avoid failure; designers had only to ensure that the available capacity of the geotechnical system is sufficiently higher than the expected demand (i.e. Load and Resistance Factor Methodologies). Yet, even when the key design requirements against collapse are satisfied, the system may still be placed into a condition in which the deformation constraints are not met (Bolton, 2012). To address these issues, geotechnical design has been developing into a predominantly performance-based approach that correlates deformation considerations to the severity of the experienced loading. As such, in earthquake-related problems, the definition of good performance of a geotechnical system is no more unique; for a low intensity earthquake the system should remain serviceable (i.e., the developed deformations should remain low), whilst for the design earthquake the maintenance of lifesafety is the single performance criterion."

Jan 1, 2016

By Steven E. Darnell, William W. Haasz, Brandon T. Buschmeier, Frederic Masse

"Landfills often cover expansive areas in locations where large building facilities or infrastructure is in high in demand after the land has been reclaimed. Most landfills have soil or fill properties that vary widely over small distances; combined with the strict guidelines and restrictions for the removal and treatment of soil or material that is on site, these projects can be a major challenge for any prospective developer. In order to make landfills suitable for the construction of any project it is necessary to conduct a detailed evaluation of the subsurface conditions. Ground improvement techniques are among the most typical methods for making reclaimed landfills suitable for the construction of any major project. The paper will discuss the approach that was taken to support a proposed warehouse in Elizabeth, New Jersey using Controlled Modulus Columns Rigid Inclusions (CMC Rigid Inclusions), which are grouted, auger-displacement elements. Additionally, we will discuss the use of Dynamic Compaction (DC) that was performed in areas outside the proposed warehouse footprint. Through the combination of CMC rigid inclusions and DC, the general contractor’s project schedule was expedited, the costs to support the warehouse were economized, and the anticipated settlement of the parking lot areas was drastically reduced. Furthermore, the paper will outline the benefits of using CMC rigid inclusions and DC methods in order to minimize the impact of working with contaminated soils from a landfill.OVERVIEW OF THE ELIZABETH WAREHOUSE PROJECTOver the past several decades the foundations industry has seen an increase in demand for the support of developments on reclaimed landfills; particularly, on the east coast where many landfills were capped before the 1980’s and steady population growth and city expansion have caused high demand for this now highly desired real estate. Unfortunately, these landfills, often as large as twenty (20) or more acres present tough geotechnical and environmental challenges for Owners planning to develop or build structures of any size on the reclaimed land. Consequently, the options for building on reclaimed landfills can quickly become cost prohibitive.Site SpecificSelected by a developer for the location of a future warehouse, the 29 acres (114,424 sq-meters) project site is located in Elizabeth, New Jersey and demonstrates the complexities of designing over a once reclaimed landfill. The landfill was used for municipal solid waste (MSW) consisting of trash, wood, metal, glass, plastic, brick, concrete fragments, and other types of debris. This landfill was capped in the 1960’s, and developed in the 1970’s for a warehouse. The new project included the demolition of the existing warehouse and the development of the site to be repurposed for a new 481,650 sq-ft single-story warehouse, surrounded by paved parking and truck loading areas. Figure 1 below, shows an overview of the project site layout."

Jan 1, 2017

By Kishore Kumar B., Eswaran Prasad C R, Srini Naik B., Ramakrishna Raju N

The authors through this paper intend to introduce the non-vibro technique of ground improvement by stone column, being used for the first time in India under the Western Dedicated freight Corridor in Mumbai area. New 2x25 KV double line dedicated freight corridor tracks, capable of carrying 32.5-ton axle load are proposed to be built on this stretch. Non-Vibro Displacement Stone Columns of 900 mm diameter were installed to improve the safe bearing capacity of the soft ground to take the loading of Dedicated Freight Corridor Railway embankment. Vertical footing load tests on single and three column groups were conducted to assess the improvement in the sub-surface condition after installation of stone columns. This paper describes load tests conducted on stone columns and analysis of the obtained results. The observed load settlement behaviour of the improved ground has also been presented. Behaviour of single and group of stone columns have been compared and criteria adopted for arriving at desired factor of safety based on the settlement observed, has also been discussed.

Nov 1, 2022

By Renzo D. Verastegui, T. C. Michael Law, Sitotaw Y. Fantaye, Alfredas Daugiala

"When completed, 520 Park Avenue will amend the Manhattan skyline and be one of the most prestigious high rise towers in New York City. The 52-story condominium building is located on a 60 by 100 feet lot on East 60th Street between Park and Madison Avenues. The geographically complex site is bounded by two fragile 5-story masonry buildings on the east and west, a mid-rise building on the north, and a New York City subway tunnel on the south. To add to this complexity, the ambitious development required 70 to 80 feet of excavation, mostly below groundwater level in highly permeable rock, to accommodate four levels of cellars. The new building also cantilevers 24 feet over a five-story historic building on the east. The limited footprint of the building coupled with large compressive and tensile axial loads, considerable base shear and over-turning moments, and the required deep excavation, presented unique foundation challenges. This paper describes how the challenges were solved with an innovative combination of permanent secant pile walls and drilled shafts.INTRODUCTIONThe project site is located at 45 East 60th Street, on the block bounded by East 61st Street to the north, East 60th Street to the south, Park Avenue to the east, and Madison Avenue to the west. As shown in Fig. 1, the site is surrounded on three sides by buildings sensitive to differential settlement. In addition, a NYCT underground subway structure lies below East 60th Street approximately 13 feet south of the site. The base of the subway structure is approximately 42 feet below the street.The project consisted of constructing a 52-story tall building. A portion of the superstructure cantilevers 24 feet over an adjacent five-story historic building. The underground construction for the new building involved a four-level basement, extending about 60 feet below ground surface. The excavation subgrade is much deeper than both the subway structure and the adjacent shallowly-founded building foundations."

Jan 1, 2016