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By Diane Reid, Antonio Marinucci, Robin Mao

Super Cells are an innovative, open-shaped bi-directional static load testing device used to promote concrete flow during placement while utilizing greater cross-sectional area of the pile to achieve large applied axial loads at relatively low hydraulic pressures (≤ 250 bar). This paper describes the results of multi-level load testing performed on a sacrificial drilled shaft that was 3.8 m (12.7 ft) in diameter and 110.6 m (363 ft) in length for the Jiaxing-Shaoxing River Crossing Bridge that spans Hangzhou Bay in Shaoxing, China. The test shaft was instrumented with embedded strain gauges and telltale rods along with displacement transducers at the top of the pile to measure the load-induced displacements along the length of the shaft. Load testing was performed twice using a Super Cell placed near the tip of the shaft, prior and subsequent to tip post-grouting, and then again using a Super Cell placed higher in the shaft. The axial resistance for the tested conventional drilled shaft was more than 5 times greater than the estimated axial resistance. In addition, the axial resistance after tip post-grouting (347,100 kN (39,033 ton)) was about 5.3% greater than the ungrouted axial resistance (329,600 kN (37,050 ton)). INTRODUCTION During the past few decades, the magnitude of axial, lateral, and flexural loading has considerably increased due to updated design codes, larger superstructures, and the manner in which extreme event loading (e.g. seismic and scour) is incorporated into design. The diameter and depths to which bored piles or drilled shafts are constructed have increased considerably during the last three decades due to the advancements in equipment technology and capabilities. In addition, monoshaft foundations have become increasingly used, as one large drilled shaft is able to replace a group of smaller diameter piles connected by a cap. Correspondingly, adequate strata, for both side and end resistance, must be discovered/determined as well as achievable to be able to construct the required foundations to support the greater design demands. As design demands have increased, the need to ensure integrity, quality, and performance of a constructed drilled shaft has become ever more crucial. Load tests are essential to validate design assumptions of side and end resistances, to assess the behavior and load transfer characteristics of the constructed drilled shafts, and to evaluate construction methods. Load tests utilizing a bi-directional static load testing (BDSLT) device can achieve considerably large applied axial loads and can be performed more economically, in less time, and in a much safer manner than conventional top-down static load testing methods.

Jan 1, 2019

By Eric Lindquist, John Compagnone, Gabriel Carvajal

"Condon-Johnson & Associates, Inc. (CJA) with the assistance of design consultant, Brierley Associates, designed and installed a water tight shoring system utilizing several ground improvement techniques jointly. Prior to the installation of the shoring system, a test program consisting of the installation and testing of 7 jet grout columns; 1 soil mix panel; 7 soil anchors and 3 tie downs was performed to verify design assumptions. State-of-the-art quality control measures were employed throughout the project.The shoring system consisted of:•,Deep Soil Mixing (DSM) wall utilizing triple axis tooling to install overlapping columns along the perimeter of the proposed excavation to a treatment depth of 54 feet.•,Installation of steel piles in DSM to provide rigidity to the wall.•,Installation of a jet grout bottom seal, installed from surface to a depth of 58 feet below existing grade.•,Installation of 153 soil anchors, 1-1/4” diameter and 47’-6” length, to tie the jet grout bottom seal to the native soil below to resist hydrostatic uplift, installed from existing grade to a depth of 91 feet.•,Installation of walers and pipe struts for internal bracing•,Installation and stressing of 117 tie downs, 1” diameter and 16 ft length, to tie the pump station mat slab to the jet grout bottom seal, installed from inside the excavated pit.Subsurface conditions at the site consist of uncontrolled fill materials to a depth of 20 feet comprised of sandy silt and clayey sand. The native soils underlying the fill generally consist of soft and compressible lean clay and silt with varying amounts of sands to a depth ranging from approximately 44 to 54 feet below ground surface, which in turn are underlain by dense to very dense silty sand. The groundwater elevation at the site is approximately 8 feet below ground surface.This paper covers the design aspects, construction, and quality control measures undertaken by the geotechnical contractor, with supporting figures.INTRODUCTIONThe owner, County Sanitation District No. 2 of Los Angeles County, designed upgrades to their existing Long Beach Main Pumping Plant Facility. The upgrades consist of a new pump station that includes a reinforced concrete below-grade wet well and dry well, a two-story operations building, two 78-inch diameter pipe inlets, two 42-inch diameter discharge pipelines connecting the existing manifold, two pipe junction structures, two insert-type junction structures, and electrical transformers. This paper focuses on the excavation shoring for the new pump station. The original shoring design concept for the pump station excavation illustrated on the contract plans consisted of pressed in sheet piles, a jet grouted bottom seal with soil anchors, 2 levels of internal bracing, and tie-down anchors to resist hydraulic uplift forces on the buried pump station."

Jan 1, 2017

By Peter Middendorp, Gerald E. H. Verbeek

"This paper will describe a brief history of the method of characteristics as an accurate solution of the wave equation, and the author's experiences with the method of characteristics over a period of 30 years.As a result of the offshore pile driving activities associated with the development of the North Sea oil fields in the 1970's, two Dutch companies initiated extensive research efforts. Heerema started to research the dynamic behavior of soil during driving and HBG (Hollandsche Seton Groep) extended the method of characteristics with a straightforward theoretical solution for the shaft friction along a pile.The research institute TNO started the development of the wave equation program TNOWAVE in the late 1970's based on HBG's friction model extension for the method of characteristics. Today the program has a worldwide application in the field of pile testing. This paper will describe its development and application over time and its relation to today's applications for driveability studies for impact hammers (PDPWAVE) and vibratory hammers (VDPWAVE), signal matching for Dynamic Load Testing (DL TWAVE), Pile Integrity Testing signal matching (SITWAVE), and Statnamic simulation (STNWAVE).The paper will highlight that these developments have been the result of multi-disciplinary and multi-national efforts and encourage geotechnical engineers to seek further developments of the wave equation program in a similar manner. Finally, the paper will indicate some areas where such further developments are required."

Jan 1, 2005

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which are 8 to 12 feet in diameter and extending over 200 feet in depth below grade. There are unique challenges associated with constructing such large and deep cast-in-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

Jan 1, 2013

By Michael Kynett, Francke Walberg, Richard Millet, Khaled Chowdhury, Mary Perlea

"Cutoff walls are the most common seepage improvement measure for levee flood control projects throughout California’s Central Valley. Cutoff walls are widely used because they can be implemented within an existing right of way in either heavily urbanized areas with limited access, or in high-value crop agricultural areas. The most commonly used seepage cutoff wall types are soil-bentonite (SB), soilcement- bentonite (SCB), and cement-bentonite (CB). Contract values for cutoff wall rehabilitation projects in the Central Valley range from several millions of dollars to hundreds of millions of dollars, and play a significant role in the reduction of flood risk in urban and rural areas. However, recentlycompleted construction of several levee improvement projects has shown limitations and inconsistencies among the commonly used technical specifications for construction of seepage cutoff walls. These limitations were evaluated by practicing engineers involved in different stages of cutoff wall design and construction. This paper describes the specification areas that typically generate design and construction issues. Recommended improvements to specifications are suggested to address these issues. The paper’s topics include: the applicability of the different types of cutoff wall materials and construction methods, quality control testing requirements, backfill gradation requirements, mixing procedures, and settlement criteria for backfill.INTRODUCTIONFlood control projects on the Sacramento and San Joaquin rivers in the Central Valley region of Northern California consist of a large system of reservoirs, bypasses, and levees. The thousands of miles of levees within the system were largely constructed and raised by local entities as need arose; this construction occurred prior to the development of modern design and construction techniques. The majority of these levees were initially constructed to protect land for agricultural development; however, a significant portion of these areas have become or will soon be urbanized. This urbanization has historically occurred in locations right up to the levee footprint. This expedient form of historical levee construction, when combined with adverse riverine geomorphology, urban development, and productive agricultural regions, has led to a levee systems with severe seepage performance issues in a real-estate-constrained setting."

Jan 1, 2015

By Martin Mcdermott, Kevin Tehansky, Robert Ross, Jeffrey Goodwin

A foundation value engineering redesign is a collaboration between the project owner, original design team, general contractor, foundation contractor and redesign team. Without the acceptance and collaborative effort of all the stakeholders, the redesign process is doomed to failure. For the addition at the Hackensack (New Jersey) University Medical Center (HUMC) we had just such a collaborative effort for the drilled shaft redesign. For a successful redesign effort, the collaboration between the foundation contractor and their redesign team needs to fully exploit the contractor’s specific equipment and experience and convey how to apply this to the project as a whole to ensure everyone is confident that the project design goals are being met. For the HUMC project, applied load testing of the drilled shafts (bi-directional and lateral) were used to provide ultimate geotechnical design values for the redesign effort. By utilizing the contractor’s preferred equipment and the redesign team’s testing and application expertise, the redesign collaboration was able to enhance a good design and make it into a great project.

By Andrew R. Klaetsch, Peter W. Deming

"The Washington Avenue tunnel in Kingston, NY was completed in 1912 to convey combined storm water and sanitary sewage. Over a mile in length, the tunnel was driven almost entirely in bedrock, with the exception of an approximately 170 foot long brick arch segment constructed in soil. About 90 years after the tunnel was put into service, persistent subsidence problems and sinkholes were observed in Washington Avenue above the shield-driven soil tunnel segment, eventually causing the important traffic thoroughfare to be closed. Subsequent tunnel inspections revealed a breach in the brick arch and a significant volume of fine soil within the tunnel. A two-phase remediation program was implemented to control seepage, reduce soil migration, and remedy sinkhole problems. The first phase included in-situ soil densification by vibratory pile probe driving to improve density in shallow sandy soil loosened by ground loss. The second phase included installation of a continuous soilcrete arch structure over and alongside the tunnel, extending to rock or compact glacial till and spanning the length of the soil tunnel segment. Overlapping vertical soilcrete columns were installed through interlayered sandy and clayey silt by jet grouting to form a continuous arch structure, using grout parameters verified by full scale field testing.PROJECT BACKGROUNDThe Washington Avenue tunnel in Kingston, NY (Figure 1) was completed in 1912 to convey combined storm water and sanitary sewage to Rondout Creek by the Board of Water Supply of the City of New York. The tunnel is over a mile in length and constructed primarily in rock. Contract documents indicate the tunnel was designed with a horseshoe shape at least 3 ft wide and 5.5 ft high."

Jan 1, 2016

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 L. D. Johnson

12 groups of 12 precast prestressed (PCPS) piles were driven in the lagoon of Kwajalein Island to support a dry dock. Pre-construction investigation of the calcareous coral sands and static pile loeid tests were performed to determine if the 7.9 by 7.9 cm (20 by 20 inches) by 26 m (85 ft) long PCPS piles embedded to a depth of 16 m (53 ft) would adequately support the dry dock. Driving records for production piles indicated that the blowcounts of the piles at the fincil embedment depth became substantially less than expected as piles wssre driven further toward the lagoon end of the dry dock and decreased to as low as 2 blows/ft. A supplemental investigation that included a static load test on a production pile, the driving of an indicator pile, and restrikes indicated that the pile foundation has adequate bearing capacity. The observed bearing capacity appears to be effected by several mechanisms including breakdown of cementation between sand particles, densification of the sands during driving, and dissipation of excess pore pressures and recementation after driving.

Jan 1, 1993

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 Bernard B. Vannoy, Howard W. Gault, Ramesh Bobba

"Treviicos-Soletanche Joint Venture (JV) and the US Army Corps of Engineers (USACE) have installed a 3800-foot long, 275-foot deep and minimum 2-foot wide secant pile barrier wall at Wolf Creek Dam in Jamestown, KY. This paper describes the methodology employed by the JV and USACE to evaluate the overlap, thickness, and position of the barrier wall. It addresses the contractual requirements, positional uncertainty, and evaluation procedures.These procedures evolved over the course of the project as various issues were identified and procedures developed to evaluate these issues. During the project, it became clear that the JV and USACE could ascertain that the wall thickness and overlap requirements could be met if the overlap based upon Koden data was at least 0.7’ in the left-right direction. For a small number of piles with overlaps between 0.5’ and 0.7’, the piles are contractually compliant yet contain a minor degree of uncertainty in the overlap. Initially, the USACE assumption was that the amount of uncertainty of verticality measurements would require more than a 1-foot measured overlap in the left-right direction to confirm an actual, contractual 6-inch overlap. With time and experience, the limit of measured overlap was reduced in accordance with greater understanding of the equipment capabilities and tolerances. Other lessons learned include the need for Quality Control/Assurance personnel to collect data at the same starting point for every pile.For every pile the JV and USACE compared analog and digital data to provide confidence that the correct digital data was used for overlap calculations. Perhaps the most important lesson learned was the importance of the JV and USACE working together and sharing all data. Overlap analysis was performed by the JV’s Barrier Wall Specialist and a small number of USACE personnel. This resulted in a high level of experience and expertise within a small group.IntroductionThe Treviicos-Soletanche Joint Venture (JV) and the US Army Corps of Engineers (USACE) have installed a 3800-foot long, 275-foot deep, and minimum 2-foot wide secant pile barrier wall at Wolf Creek Dam in Jamestown, KY. The wall was installed through a 6-foot wide Protective Concrete Embankment Wall (PCEW) which was installed two feet into rock. The PCEW protects the embankment from erosion of drilling fluids during subsequent operations. Below the PCEW the piles were installed to a specified elevation (staggered at 475’ and 473’ below the 748.2’ work platform). The Ordovician limestone and shale bedrock is flat lying with few vertical fractures. These conditions facilitate the advancement of pilot holes with very low deviations (with considerable credit to the JV’s drillers and steering engineers). The pilot holes were spaced on 31.5-inch and 35-inch spacing. Subsequent enlargement of the pilot holes to 50’ resulted in a continuous wall. This paper addresses the requirements and procedures to assure that the wall was as wide, deep and continuous as specified."

Jan 1, 2015

By Evangelia Ieronymaki

Civil engineering education relies on traditional methods of teaching, comprising mostly of deductive instruction by presenting the theory, followed by applications. This paper presents an alternative way for teaching foundation design to senior students, introducing a more inductive approach. The students are presented with a project/game adapted to a real-world problem at the beginning of the course. They are asked to identify the correct steps and methods throughout the lectures, for reaching an appropriate solution that they document and present at the end of the course. To make the project more enjoyable, the project has the format of a game where the students compete with each other on completing the task faster and more efficiently. The goal of this teaching approach is to enhance the ability of the students for problem solving and the engineering way of thinking, while playing a game. In the end, the students were requested to respond to a survey regarding the efficiency of this project/game on their learning. The results showed that students prefer more inductive methods for a design course, feeling that this project made them think more like engineers, while the ‘game’ twist of it made the whole course more fun. INTRODUCTION Most civil engineering courses are taught in 2019 the same way they used to be taught 40 years ago in the 80s. Classic methods are mostly deductive, where the instructor presents the theory first and then applications of that theory follow. Little or no attention is given initially to why the theory was developed or what are the problems it solves. The applications of the theory, and thus the purpose it serves, come only in the end and after methodologies have been presented, leading the students to show low interest in the material. As Albanese and Mitchell (1993) have reported, people are mostly motivated to learn things when they clearly see the need to know them. This explains the students’ little motivation that, if any, comes mainly from the fact that the material may be useful either in other courses or in their future careers. On the other hand, there are alternative inductive methods of teaching, where the role of the students is more active. A lot of researchers have highlighted the benefits of inductive methods in teaching engineering courses. Based on Prince and Fedler (2006), inductive methods include; a) inquiry-learning, b) discovery learning, c) problem and project-based learning (PBL), d) case-based teaching, and e) just-in-time learning. Inquiry-learning is maybe the most traditional method of inductive teaching/learning methods, where the instructor asks questions or poses problems and the students need to apply the theory they have learnt in order to find the solution (Bateman 1990; Prince 2004; Lee 2012). Similar to inquire-learning is the discovery learning, where students have to find the solution to a problem or answer to a question, while the instructor simply provides feedback to the students without guiding their efforts (Leonard 1988; Westbrook and Rogers 1994).

Jan 1, 2019

By Marcel Bielefeld, Joost Bakker, Rob van Dorp

Pile load testing can be performed by a static, rapid or high strain dynamic (generally designated as dynamic) testing method. The static load test is often considered the “gold standard” of testing with the other methods merely ‘alternatives’. However, the rapid load test, as a quasi-static test, has all the positive elements of the static alternative: the direct measurement of loads and displacements. Moreover as stress wave phenomena have no influence, the interpretation of rapid load test results is more straightforward than that of dynamic testing, and also independent of the person performing the interpretation. This paper will explore the Rapid Load Testing method and illustrate the advantages and limitations through a case study in Rostock, Germany

May 1, 2022

By Seth Robertson, Daniel Belardo, Travis Coleman

Thermal Integrity Profiling (TIP) is a non-destructive method used to evaluate drilled deep foundation integrity. This integrity testing method is specified more frequently, and is becoming an industry standard in the transportation and private construction sectors. This testing method utilizes heat generated during the concrete/grout curing process to assess deep foundation integrity over the evaluated length. With compilation of the measured temperature versus time and installation records, a model of the Effective Average Radius versus measurement depth is generated. The generated effective shaft model is highly dependent on specific construction details, subjective modeling parameters, and proper interpretation of concrete/soil heat dissipation characteristics. Key components of the TIP analysis include both qualitative and quantitative assessments. Qualitatively, variations or sharp reductions in temperature profiles may indicate potential anomalous regions. Quantitatively, a correlation is established between measured temperatures and estimated Effective Radii for subsequent integrity evaluation. Best practices in processing the TIP measurements are presented, including selecting the optimal time for analysis, normalizing the thermal profile, and proper interpretation of potential anomalous regions. Recommendations for implementing mitigation efforts and interpretation of the TIP results are presented.

Sep 8, 2021

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 Emilie Lapointe, Fernando Famania

"A reliable determination of the in-placed cement factor, as defined by mass of cement over volume of final element of treated soil, allows the optimization of cement usage to achieve treated soil requirements. Cement determination tests were performed on soil-cement samples, both fresh (as per ASTM D5982) and hardened (as per ASTM C1084). This paper reviews the calibration work required for the D5982 determination of cement content by the heat of hydration method used on soil-cement samples obtained by wet-grabbing. Using the correlation curves in the field provides a rapid assessment of cement content hence optimizing the cement injection rate to match laboratory tests previously conducted. Cement determination tests on hardened soil-cement specimens from wet-grabs and cores were performed using the oxides method. Samples, both cored and wet-grabbed, were tested in a given cement-treated element, and in different soils to inform on the expected variation in cement content from field installation. Results indicate that both cement determination methods are valid for forensically determining cement contents and that they provide better assessment than the conventional field reporting methods. The methods can be used to optimise the cement usage as well as for Quality Assurance, especially when coring quality is poor.INTRODUCTIONThe degree of improvement, and inherent strength, which is attained in a deep-mixed soil is a function of many factors. The binder type, the existing soil, the mixing conditions and the curing conditions are the categories of factors influencing the strength of a given cement-treated soil as agreed by the deep mixing community and as summarized by the Coastal Development of Technology [CDIT] (2012). Given a site with existing soils and conditions requiring soil improvement using a given binder, the designer and/or contractor can control the mixing conditions. Mixing conditions are inclusive of the degree of mixing, mixing duration and the quantity of binder. Once a deep mixing method has been chosen to mix optimally the in-situ soil, the quantity of binder is the only remaining factor to be optimized. The quantity of binder, in the construction industry is commonly referred to as the field binder factor [ar] and defined by the mass of binder over the volume of soil treated with kg/m3 as unit. In research, the quantity of binder is referred to as the binder content [Cc] and expressed as a ratio of the mass of binder over the mass of dry soil mixed."

Jan 1, 2015

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 Ali Azizian, Brian Hall

"Driven piles were selected to support the Fraser Heights Bridge bents. Piles were a key component of the top-down construction approach, which was adopted for minimizing potential impacts on an environmentally sensitive wetland. Project requirements mandated verification of pile capacities using dynamic methods. More than 40 Pile Driving Analyzer (PDA) tests were performed. The subsurface conditions were highly variable. On the east side, piles extended through loose sands, soft silts/clays, and two peat layers and were founded in glacial till-like soils at about 45 m depth. However, on the west side, till-like materials were so shallow that it was difficult to drive the piles sufficiently deep to obtain the necessary lateral support. This paper provides an overview of the geotechnical considerations of the bridge design and top-down construction approach, and expands on the presentation of PDA results and how they compared to pile capacity estimation methods and parameters recommended in the applicable design codes.INTRODUCTIONThe Fraser Heights Bridge (FHB) was a component of the Fraser Heights Connector (FHC), a 2 km section of the South Fraser Perimeter Road (SFPR), constructed as part of the Port Mann/Highway 1 (PMH1) Improvement Project. The FHC is located in northeast Surrey BC (Fig. 1).Two major design and construction determinants were: 1) a mandated tight schedule to provide a non-tolled alternative to a new toll bridge; and, 2) an obligation that construction had to occur with minimal impact on the environmentally sensitive wetland the FHB crossed, including limiting the footprint of the permanent and temporary works to less than 45 m2, and prohibiting construction access onto the wetland. Construction equipment was only allowed on the wetland on temporary trestles or on the finished structure. This latter requirement resulted in the bridge being constructed span by span, using a top-down approach."

Jan 1, 2016

By James Coull, Brian Wilson, David Siddle

"In 2012, Golder Construction Inc. was awarded a Design-Build contract for the design and construction of an extensive, deep ground improvement scheme to support up to 20 metres (66 ft) high Mechanically Stabilized Earth walls and bulk earthworks required for the development of the proposed Kitimat Liquefied Natural Gas (LNG) facility at Bish Cove, British Columbia (BC). Utilizing Cutter Soil Mixing (CSM) to construct barrettes consisting of overlapping rectangular panels of in-situ cement-treated soils, a deep mixing scheme, covering an area of approximately 12,900 m2 (15,430 yd2) and comprising some 1645 CSM panels to depths of up to 30.7 m (101 ft), was developed to provide the required static and seismic stability for the LNG structures, and meet the project-specific performance criteria.CSM panels were constructed through varying thicknesses and discontinuous layers of fine-grained, very soft to soft marine deposits, and loose to compact sands, with occasional interbeds of dense sands and gravels. Panel completion criteria was based on soil response factors, as measured by the CSM equipment, with the design requiring a typical embedment of about 2 m (7 ft) into dense silty sand to sand and gravel to provide the required bearing. A total volume of approximately 73,900 m3 (96,660 yd3) of soil was treated with cement to consistently yield average unconfined compressive strengths exceeding 2.5 MPa (363 psi).This paper outlines the challenges associated with the construction and quality control of this large deep mixing scheme in highly variable geotechnical conditions at a remote location with barge-only access, and limited communication facilities. Specifically the paper will discuss the logistical challenges faced and solutions adopted for the project; equipment redundancy requirements for a 24/7 operation; the impacts of wear and tear, as well as variability in subsurface conditions on productivity; quality control processes adopted for the project, including the value of provision of an on-site laboratory; and materials handling issues, and their impacts on mix design and quality control."

Jan 1, 2017

By Jahnavi Parmar, Pranav R. T Peddinti, Saloni Pandya, P. S. Prasad

Coastal cities are in desperate need of suitable land to meet the ever-increasing demand for urban infrastructure to support commercial, residential, tourism, and off-shore activities. Countries with a lengthy coastal line, such as India, possess significant areas of wide spread highly saline soils subjected to periodic seawater intrusion. One such soil stratum was encountered at the Gulf of Cambay, Bhavnagar district, Gujarat, India. Due to the high volume of river runoff, the Gulf has a positive water balance. The relative humidity ranges from 65 to 86 percent, making the climate semi-arid to sub-humid. The high salinity, mineral content, basaltic origin, and deeper water table offered the impetus to investigate applicability of various soil treatment options for such saline soils. Admixture stabilization techniques have been shown to help with problematic soil features. The Current study aims to determine effectiveness of addition of locally available lignite fly ash (10% - 30% by weight) and cement (6% - 9% by weight) to Bhavnagar saline soil in respect of strength, electrical conductivity and CBR. In this assessment, a comparison of stabilized and unstabilized saline soil mixtures is expected to highlight the need of understanding influence of treatment on instinctive performance of stabilized saline soils, as well as assist practitioners in efficacious treatment of extreme saline soils for diverse geotechnical and construction applications.

Sep 1, 2022