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By Nadir Ansari, Brian W. Wilson, Marina S. W. Li

"A hybrid Deep Mixing (DM) shoring system was recently constructed for a high-rise development in downtown Vancouver, British Columbia, Canada for the temporary support of a five-level basement excavation. The site is bounded by an existing bridge off-ramp structure along its longest side and by city streets on the other two sides, which formed a truncated triangle in plan. A conventional secant pile wall was installed along the longest side, about 380 ft (116 m) in length, of the site. Hybrid shoring walls (HSW) 1 and 2 were installed along two shorter sides with each being 235 to 246 ft (72 to 75 m) long. HSW 3 completed the excavation support system along the shortest side with a length of about 55 ft (17 m). Cutter soil mixing (CSM) was proposed by the excavation and shoring design-build team in lieu of conventional secant piling. CSM was the preferred method to construct the infill panels between soldier piles because of the speed at which the shoring system could be constructed in the variable fill, peat, wood waste and overburden. Design ConsiderationsTo minimize the impact on buried utilities along the outside perimeter of the excavation, the temporary shoring was designed to limit the lateral displacements to less than 0.8 in (20 mm). Factors taken into consideration for shoring design included the lateral earth pressures from the fill and native soils, groundwater pressures, temporary construction loads (e.g., crane or heavy plant/equipment), and permanent structural requirements. The subsurface conditions at this site typically consisted of fill (cohesive and granular), overlying peat and/or wood waste, overlying clayey silt to sandy silt, overlying weathered to dense to very dense clayey silt till to sandy silt till with silt layers. Localized, perched groundwater was observed within the fill, peat, wood waste and sandy silt layers above the dense till."

Jan 1, 2017

By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan, Joseph Toth

The difficulty in material characterization and the erratic response of cemented soil layers, such as caliche in the Las Vegas valley, creates challenges for practicing engineers to reliably predict the response of deep foundations. The focus of this paper is the numerical prediction of axial response in drilled shaft foundations, which are commonly used in infrastructure projects (i.e., bridges and tall buildings) in Las Vegas, NV. The prevalence of hard caliche layers with variation in the degree of cementation add to the complication in numerical modeling. In this study, the applicability of two existing t-z models, developed for Florida limestone and soft rock, was evaluated based on numerical simulations of three bi-directional load tests conducted at caliche-dominant sites. The corresponding top-down load tests were also simulated for further assessment. A MATLAB-based finite-difference program, NVShaft, has been used to implement the mentioned t-z models in axial load analysis. Complexity originating from drilled shaft construction and the interaction with caliche during one axial load test resulted in a stiffer predicted response compared to measure data. For the other two load tests, both t-z models produced comparable load-displacement responses. It was observed that the t-z model for Florida limestone predicted relatively stiffer responses and higher drilled shaft capacity.

Sep 8, 2021

By Sushant Upadhyaya, Deniz Karadeniz

As part of the widening of I-64 in Williamsburg, Virginia, an extensive subsurface exploration program consisting of Standard Penetration Tests (SPT), Cone Penetration Tests (CPT), Dilatometer Tests (DMT), and Vane Shear Test was performed. In addition to these in-situ tests, an extensive laboratory testing program was completed including Consolidated-Undrained Triaxial, Unconsolidated-Undrained Triaxial, Direct Shear, and consolidation tests. The strength and the compressibility properties are deemed conservative for Yorktown and St. Mary’s Formations when evaluated based on the current topography, the existing overburden pressure and SPT values. SPT exhibited low blow counts especially within Yorktown Formation due to the increased excess pore water pressures resulting in a localized liquefaction at the tip of the split spoon sampler corresponding to remolded or fully softened strength of the soil. Therefore, the applicability of the SPT correlated soil parameters somewhat leads to conservative designs with deeper piles to achieve a desired structural load demand. Generally, the in-situ estimated soil design parameters are found to be comparable with the laboratory test results corresponding to long-term resistance gain with time. It is of practical importance to employ realistic soil design parameters for design applications such as pile foundations to provide cost and schedule savings. This paper presents a discussion on the soil strength estimates and variability from in-situ and laboratory tests for realistic strength characterization of Coastal Plain deposits.

By William F. Starke

"The Ontario College of Art & Design (OCAD) located in Toronto, Ontario, found itself in dire need of space due to increased enrollment, leading them to embark on a major expansion and redevelopment on campus. The expansion entailed an additional 115,000 sq.ft. (10,700 m2) and a new major structure was required, as well as extensive redevelopment of existing buildings. The new Sharp Centre for Design was designed by acclaimed British Architect Will Alsop, of Alsop Architects, in a joint venture with Toronto-based Robbie/Young + Wright Architects. The OCAD campus is cramped for space and the design selected was a structure built over top of existing structures. The building has been described as resembling a “shoebox in the sky”, supported on raked columns transmitting high lateral forces as well as compression load to the foundations. There are 12 such supports, each supported by an individual caisson. In addition, the project entailed installation of other caissons in the courtyard area with the construction work accomplished under very confined conditions among the existing structures. The remarkable design for the new Ontario College of Arts will surely make it another of Toronto’s architectural landmarks. Several things make this project stand out as a unique deep foundations project.First is the architectural design. Words cannot do it justice: the picture is the only effective way to start to describe it. This is a big two-story box, built over the top of a fragile existing building. The underside of the box is 86 ft (26m) above street level. Students remained still inside the old building while construction was going on around and above them. There were serious concerns about vibration – not only its effects on the academic life; but more significantly, upon the stability and safety of the old building, which rests somewhat shakily on shallow spread footings.Steel stilts that look like toothpicks when scaled against the new and existing structures support the box. The stilts are much sturdier than they appear from the pictures, but it is easy to visualize the complexity of the loads they transfer to the foundations below."

Jan 1, 2004

By Qingwei Joshua Ong

Tension piles, also known as uplift or anchor piles, are necessary to resist uplift forces that might cause structural distress. In excavation projects, most uplift forces are developed because of hydrostatic pressures, and so tension piles are subjected to a great deal of tensile forces. Most current methods of design for tension piles completely neglect the tensile strength contribution of concrete, relying only on the steel members to carry the tensile stresses, resulting in an overly conservative design. The stressstrain behavior of the composite material of concrete and steel must be considered for a realistic simulation of tension piles. This paper will examine a case on a tension bored pile in typical soft clay to demonstrate the importance of considering the tension strength and tension softening of the concrete.

Nov 1, 2022

By Richard E. Sylwester

Evaluating surface and subsurface conditions for marine foundations (bridges, causeways, terminals, etc.) is often done with a limited amount of data. Subsurface information for these projects is primarily acquired using traditional methods, such as boreholes, test pits or divers, which tend to be expensive and limited in the area of coverage. A number of geophysical methods, including precision bathymetry, sidescan sonar, and seismic reflection or subbottom profiling are extremely cost-effective and obtain significantly more data than can be acquired using traditional intrusive methods. These geophysical methods provide detailed surface images and continuous profiles of the subsurface stratigraphy. This information can be invaluable for selecting the best location for geotechnical boreholes and to map potential geohazards such as submarine slides and filled or open scour holes. Offshore investigations conducted for a proposed highway bridge (Knik Arm Bridge, Cook Inlet, AK), the retrofit of two existing bridge (Antioch and Dumbarton Bridges, CA) and a proposed cruise ship terminal (Ketchikan, AK) used a combination of geophysical methods to map water depth, detect and map debris on the seabed, map the thickness of unconsolidated sediment, determine the depth to bedrock and identify potential geohazards such as scour holes. The results of the geophysical investigations will be used to select locations for obtaining geotechnical borings, to extrapolate geologic information between existing or proposed boreholes, evaluate the potential depth of scour and design a pile support pier. Geotechnical engineers, offshore contractors and bridge designers are realizing the importance of the early use of offshore geophysics for (i) site characterization, (ii) to reduce the uncertainty of geotechnical conditions thus avoiding designs that may be overly conservative and thus more expensive and (iii) to assist in selecting locations for geotechnical borings.

Jan 1, 2013

By Ambarish Ghosh, Chitralekha Ghatak, Tanumaya Mitra, Tarun Sengupta, Sajib Das, Sankar Kumar Nath

"Currently construction of important structures like bridges, flyovers and high rise buildings in and around Kolkata are in full swing. These structures have mostly pile or well foundations. The design methodology and construction techniques are being employed keeping in view both the safety and economy of the project. The data presented in this investigation have been taken from Geotechnical Investigation report of Component B in connection with construction of Extradosed Cable Stayed Bridge over River Hooghly in Hooghly and Nadia district of West Bengal, India. The investigation site is located within close proximity of Eocene Hinge Zone which is being taken as the principal contributor of Earthquakes in and around Kolkata. Considering the importance of the project detailed and exhaustive geotechnical investigation has been carried out and site specific response spectra have been generated for analysis and design of the bridge. This paper presents site specific response spectra, liquefaction analysis and comparison of lateral load carrying capacity of pile using Winkler approach and IS 2911 guidelines.INTRODUCTIONPile foundations are used to transfer the load of the super structure through soft soil deposit to deeper bearing stratum by means of skin friction or end bearing or both. Pile foundations are regarded as a safe alternative for supporting structures in seismic areas and have been used for this purpose in non-liquefying as well as liquefying soils. But their design in case of potentially liquefiable soil is quite different from that of non liquefiable soil. In liquefiable soil the progressive buildup of excess pore water pressure will cause stiffness degradation and loss of strength which in turn will induce additional shear force and bending moment in the pile. The mechanism of pile behavior in liquefying soil has been investigated by several investigators in the recent years based on observations of pile performance during earthquakes and studies in the centrifuge and Shake Table tests. Exhaustive geotechnical investigation has been carried out along the proposed alignment of the Extradosed Cable Stayed Bridge i.e., along Baropara, Bansberia ROB, Ishwar Gupta Bridge, Saraswati River to collect disturbed as well as undisturbed soil sample, to develop average soil profile and to determine the design parameters. The proposed project site is very close to Eocene Hinge Zone, which is basically a strike slip fault, capable of generating an earthquake of Mw 6.7. Thus it is evident that the proposed Bridge needs to be designed considering the adverse geo-hydrological condition as well as the earthquake aspects needing special attention following the state-of-the-art technology as guided by relevant codes and published literatures. Considering the soil profile of these locations ground response analysis has been carried out using equivalent linear method to determine the site amplification. Site specific response spectra have been developed for the four zones and zone factors have been determined. The computed zone factors are 0.198g, 0.195g, 0.195g and 0.20g for the four zones respectively, much higher than the zone factor 0.16g, which is for zone III, as stipulated in IS 1893:2002."

Jan 1, 2015

By Frederic A. Verheyde

The CPT pile design method of the ‘Laboratoire des Ponts et Chaussées’ (LPC) uses the cone resistance (qc) for the design of axially loaded piles. It was originally proposed in 1982 and was revised in 1993 and 2012. It has been widely used in France for several decades and is included in the current French pile design code. The objective of this paper is to summarise the two first versions (1982 and 1993) of the method and to detail the most recent one as described in the current French pile design code (AFNOR 2012).

Nov 1, 2022

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 Venkata Krishnaiah Yeddala, Sai Vivek Adari, Suresh Kumar Velugu

Assam cancer care foundation (ACCF) proposed the construction of hospitals and related facilities across 18 locations in the state of Assam-India. Tezpur is one among the 18 locations of Assam with high seismic risk. The strata at the site are comprised of mostly fine silty sands of lower SPT- N values. The water table is also encountered and ranging from 1 m to 2 m below EGL. Since the site lies in seismic zone V as per IS 1893, detailed liquefaction analysis is carried out for all five boreholes and indicates that soil is liquefiable and ground improvement is inevitable up to a depth of 15 m below existing ground level. To mitigate the liquefaction potential and enhance the seismic performance of the soil, ground improvement using stone columns by Wet top feed Vibro-replacement method is proposed. Also, the differential settlements can be avoided effectively under the raft foundation with Vibro Stone Columns. In this paper, field test validation results such as Pre and post-SPTs and ECPTs to access the extent of ground improvement, along with other information adopted in this project presented.

Nov 1, 2022

By Lois G. Schwarz

I did a project (Sungai Piah) as a consultant to your firm in Malaysia, where we were faced with a similar situation as sketched out in your question. The following is what we did for the grouting of the primary holes, which were both located upstream of the plug as well as downstream: We used a hydrophobic MDI based semi-rigid polyurethane prepolymer in the first phase of the grouting operation when grouting under water flow conditions. Then in the second phase and also for the contact grouting we used a two component water compatible polyurethane elastomer. And then for deeper formation grouting, when all the water flow had been stemmed in the vicinity of the plug, we used a regular (balanced stable) cement based grout. So it may not exactly answer your question, but we first used hydrophobic grout because it is very efficient to grout a formation through which water flows. We didn't stop all the leaks day-lighting downstream of the plug or all water running through the formation near the plug, but the flow of water through the rock formation adjacent to the plug was reduced by 99.9%, after completing the urethane grouting. This facilitated the placement of cement based suspension grouts without wash-out.

Feb 10, 2003

By Charles M. Wilk

"Solidification/stabilization (S/S) treatment is used to treat hazardous wastes for disposal and in the remediation/site restoration of contaminated land . SIS is also an increasingly popular technology for Brownfield (industrial property) redevelopment, since treated wastes can often be left on-site and to improve the soil for subsequent construction. This paper discusses the applicability of the technology to various wastes, basic cement chemistry relating to SIS, tests used to design treatability studies and to verify treatment, basics on implementation of the technology in the field , and examples of SIS use at brownfield sites, including a former wood preserving site, former manufactured gas plant sites, a former electric generating station, and a shopping mall development.INTRODUCTIONSolidification/Stabilization (S/S) is a widely used treatment for the management/disposal of a broad range of contaminated media and wastes; particularly those contaminated with substances classified as hazardous in the United States. The treatment involves mixing a binding reagent into the contaminated media or waste. The treatment protects human health and the environment by immobilizing contaminants within the treated material. Immobilization within the treated material prevents migration of the contaminants to human, animal and plant receptors. SIS treatment has been used to treat radioactive wastes since the 1950s and hazardous waste since the 1970's (Conner 1990). SIS continues as a cornerstone treatment technology for the management of radioactive waste, hazardous waste, and site remediation and Brownfield redevelopment."

Jan 1, 2005

By Daniel P. Stare, Lucian P. Spiteri, Christopher M. Hallahan, James C. Myers

Buckeye Lake Dam was substantially remediated between 2015 and 2018 as a result of unacceptable dam safety performance. A permanent seepage cutoff, consisting primarily of a soil mixed cutoff wall (SMCW) with occasional sections of steel sheet piling, was constructed along the dam alignment. Closures were required at the terminus of the soil mix elements with existing structures or coffer cells, and at locations where new sheet piling was constructed parallel to the new soil mixed cutoff wall, creating a short circuit seepage path. The original proposed design to construct these closures included permeation grouting methods with chemical grouts. However, a combination of multiple chemical grout types, multiple grout pipes, and an extensive post-grouting verification program was required to ensure the design intent was achieved. After award of the project, the specialty grouting contractor elected to evaluate jet grouting as an alternative closure construction method. The advantages of the jet grouting option offered potential schedule and cost savings to the project as well as a superior product for seepage reduction, given the mixed soil conditions at the site. This paper presents an examination of the site conditions and project goals for the construction of the proposed closure elements for the rehabilitation of Buckeye Lake Dam. Descriptions of the original and alternative treatment methods are provided, with expected performance results. A description of the relative strengths and deficiencies of each method, as well as the feasibility and constructability of each method is provided. The implementation of the jet grouting program is presented, including a discussion of the design elements, quality control test methods, movement monitoring, and verification test methods. This paper also examines the risks associated with jet grouting and how those risks were mitigated during the grouting operations. HISTORY Buckeye Lake is situated approximately 28 miles east of Columbus, Ohio and is managed and operated by the Ohio Department of Natural Resources (ODNR) as part of the Ohio State Parks system. The lake is impounded by natural features that exist along the south and east banks of the reservoir, and by the embankment structure constructed along the north and west banks of the reservoir (see Fig. 1). The reservoir site was originally a natural swamp and the original purpose of the constructed dam and reservoir was to provide water to the Ohio and Erie Canal System. Several dam alignments and configurations were constructed during its early history; however, the original embankment is comprised of homogeneous earthen fill. The embankment is 15 ft (4.6 m) high and extends 4.1 miles (6.6 km) from the North Shore abutment along the east, continuing to the abutment at Lieb’s Island to the West. Several spillway and outlet structures exist along the embankment alignment. Most noteworthy are Seller’s Spillway and Amil Spillway. Fig. 2 is a Plan View of the embankment alignment and appurtenant structures at Buckeye Lake.

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 Ashirbad Satapathy, Sanket Rawat, Ramanand Shukla, Ravi Kant Mittal

Bearing capacity factor (Nq) and Adhesion factor (α) are the key parameters for analyzing the load carrying capacity of pile foundations embedded in cohesionless and cohesive soils respectively. Numerous models are available in the form of charts or equations for the computation of these parameters and hence, have been adopted by most of the International and National standards. Indian Standard for the Design and Construction of Concrete Pile Foundations, IS 2911–Part 1 (2010), also makes use of charts detailed in its Annexure B. However, the sources of these charts have not been specified clearly, making it difficult to back-refer to the actual models to assess their basis for resolving any critical scenarios encountered during design. The present study aims at acquiring a distinct understanding of the development of these charts in order to bring more clarity to the design process of pile foundations. The given charts have been compared with various models specified in existing literature and international standards for the calculation of Nq and α for both driven and bored piles and hence, the basis of Indian Standard charts has been identified. Moreover, it is evident that the use of these charts complicates the process of automation of analysis and design of pile foundations as well as the associated optimization studies. Additionally, the manual entry of data especially, from the logarithmic graph of Nq, escalates the chances of error thus, making it a critical concern for design offices. Therefore, this paper also presents a non-linear regression model for Nq and α, developed using NCSS software for both driven and bored piles. Through multiple iterations, the value of coefficient of determination for Nq and α has been found to reach greater than 0.995. The developed equations can be simplistically used for both manual and automated analysis of pile foundations.

Nov 1, 2022

By Adrian Gygax, Sarah Gaib, Rod Kostaschuk

The British Columbia Ministry of Transportation and Infrastructure (Ministry) recently completed a slope stabilization project at Ten Mile Slide on Highway 99. The highway is an essential part of the road network connecting the British Columbia (BC) coast with the interior of the province. The landslide was first identified in the mid-1980s and has retrogressed more than 250 m upslope since then, leading to continual and expensive repairs to the highway. The Ministry engaged BGC Engineering Ltd. (BGC) and their structural sub-consultant Gygax Engineering Associates Ltd. (GEA) to develop a stabilization scheme that would halt the slide with an acceptable level of residual risk. The design required careful consideration of construction stages and the stresses induced in the structural components as the slide movement was progressively stopped as construction advanced. Four stabilization design options were shortlisted with the preferred option selected in Fall 2016. The selected solution comprised the construction of five rows of post-tensioned soil anchors upslope of the highway and a tied-back concrete tangent pile retaining wall for the roadway itself as well as reconstruction of the highway alignment, grade and drainage through the slide. Works were installed by top-down construction within defined time allowances stipulated in the contract. Significant engineering was undertaken beyond standard design processes for this complex project, such as comprehensive geotechnical investigations, aerial and terrestrial laser scanning and change detection analyses, pre-production test anchors, detailed geo-structural numerical modelling and due diligence activities to validate and optimize the design. The stabilization works have been very successful with the slide response being as predicted and the highway operating again as full two-lane service.

Oct 1, 2022

By Donald Bruce, Alex Reeb, George Filz, Wesley Schmutzler, Mitsuo Nozu

"One million seven-hundred thousand cubic yards of deep mixing were installed to support an elevation raise of an earthen levee known as LPV 111, which is located in east New Orleans. The deep mixing was done by two contractors using somewhat different technologies, but producing elements of the same size. As part of the quality control and quality assurance program, 507 deep-mixed elements were cored and 5,082 specimens were strength tested in unconfined compression. This paper presents data from the coring and testing program. Very high percentages of the core run lengths were recovered, except during one period for one mixing technology. The coring methods are described, and reasons for the isolated episode of low recovery are discussed. The strength data show that the specification acceptance criteria were satisfied. Statistical parameters of the strength data are provided, and trends between strength and the following factors are discussed: depth, soil type, binder factor, and project-specific experience. Photographs of longitudinal cuts of core specimens are presented. Important lessons learned from this unusually large project are described.INTRODUCTIONThe Lake Pontchartrain and Vicinity Hurricane Protection system included a project known as LPV 111, which is an approximately 5-mile long segment of levee and floodwall located in east New Orleans along the Gulf Intracoastal Waterway and adjacent to Bayou Sauvage National Wildlife Refuge (Cali et al. 2012). The majority of the project consisted of a raise of an existing earthen levee from an existing crest elevation of about 18 ft to a new crest elevation of about 28 ft. The underlying soils were weak and compressible, providing inadequate support for the raised levee. Ground improvement in the form of deep mixing was selected to provide the necessary stability and settlement control for the raised levee.The US Army Corps of Engineers (USACE), New Orleans District, was the governmental agency in responsible charge of the project, including approval of design, construction, and payment. The lead designer was URS Corporation, and the general contractor was Archer-Western-Alberici (AWA), working in alliance with TREVIICOS South (Trevi), who, together with Fudo Construction (Fudo), performed the deep mixing.As part of the quality control and quality assurance program, over 500 production deep-mixed elements were cored, the cores were carefully logged, and over 5,000 unconfined compression tests were performed. In addition, selected specimens were carefully photographed before and after longitudinal saw cuts to expose the interior of the specimens. This paper provides a summary of the coring and testing performed on the production deep-mixed elements."

Jan 1, 2015

By Takefumi Takuma, Ali Fayad, Shigeru Kambe

"This paper discusses the unique design and construction circumstances of the cantilevered dual sheet pile walls and the Accordion Sheet Pile Wall for the repair and upgrade of the East Garden Grove-Wintersburg Channel in Huntington Beach, California that was concluded in 2014. It also describes the 2008 Emergency Sheet Pile Project for the same channel. Both projects utilized the Press-in Piling Method for its low noise and almost no vibration advantages.BackgroundThe East Garden Grove-Wintersburg Channel is part of the Orange County Flood Control District (OCFCD) and is operated and maintained by OC (Orange County) Public Works (see Figure 1 for its location). The channel, referred to as OCFCD facility # C05 (C05), had suffered significant toe undercutting and slope erosion of its levee due to a series of storms. These began after the facility was constructed in the 1960’s and culminated in 2005. Consequently, the levee was deemed significantly deficient and was eventually declared as a local emergency in 2007. C05 was an incised channel and its levee was constructed primarily from native materials. Operation and Maintenance (O&M) personnel notified the design staff at OC Public Works to be aware of major consequences associated with the dilapidation problem in the most downstream reach of the channel in the vicinity of the Bolsa Chica Wetlands Restoration Project. In 2007, the Orange County Board of Supervisors declared a local emergency to fix the levees with sheet piles to be driven by the Press-in Piling Method, hydraulic pushing piles into ground by holding onto previously installed piles. The project that ensued represented the first in-tandem use on the West Coast of the United States of the Press-in pile driver with its GRB System (Press-in pile driver, a support crane and pile transporter travel on top of already-driven sheet piles). This is further discussed in this paper in the sections titled “Press-in Piling Method” and “GRB System”, respectively. The project repaired approximately 3,800 feet of erosion on the north levee of C05 with 45-foot long cantilevered sheet piles. The sheet piles design constraints are discussed in this paper in the section titled “C05 2008 Emergency Sheet Pile Project (Phase 1)”. Between 2012 and 2014, another mile’s worth of levee reach was improved with the Soil-Mix-Sandwich (SMS) Method. This concept consisted of deep soil cement mix (DSCM) columns sandwiched within the dual rows of sheet piles. Additional details on the SMS, its DSCM construction, and its hybrid geo-structure design concepts are well beyond the scope of this discussion, which is primarily focused on sheet piles. Instead, the interested reader is referred to two papers on the SMS and its DSCM metrics (Fayad, 2015; and Arora, et al., 2015). These were presented and published in the Proceedings of the Deep Foundations Institute (DFI) 2015 Conference on Deep Mixing. Hence, in the section of this paper titled “C05 SMS Dual Sheet Piles Project (Phase 2)” only the sheet pile design constraints of the SMS are covered. Finally, in the area where the project traversed the Alquist-Priolo zone of the Newport-Inglewood tectonic fault, an expandable and deflectable sheet pile wall was used to isolate the flood channel from the Bolsa Chica wetlands. Its details are addressed in the section titled “C05 Accordion Sheet Pile Wall (Phase 2)” of this paper."

Jan 1, 2017

By Craig M. Shillaber, Joseph E. Dove, James K. Mitchell

"This paper addresses two primary factors affecting the sustainability of Deep Mixing Methods (DMMs): construction materials and handling of the spoil from wet mixing methods. We examine these factors within a life-cycle embodied energy (EE) and carbon dioxide (CO2) emissions accounting framework, using the LPV 111 project in New Orleans, LA as a case history. The underlying assumption is that project planning and preliminary design have determined that a DMM is the best ground improvement alternative for achieving the broader aims of sustainable development. While EE and CO2 emissions are direct measurements of environmental impact alone, we illustrate how their minimization can also influence the social and economic consequences of the project. It is recommended that DMMs use lower energy and carbon material alternatives to Portland cement and lime in the binder whenever possible, with preference given to locally sourced materials. Currently available alternative cementitious materials include fly ash and slag, which are waste products from other processes. In addition, recycling the spoil material from wet mix methods on site is recommended. If the material cannot be recycled on site, transporting it to a processing and recycling center for later use as fill is preferred over landfilling. INTRODUCTIONWithin the geotechnical community there is an increased appreciation for sustainability considerations, which are an important component of the planning, design, construction, operation and maintenance of projects. An assessment of project sustainability includes holistic life cycle thinking, systems analysis, environmental impact assessment, use of safe and benign materials, awareness of local societies and cultures, social equity, protecting human health and well-being, and monetary costs (Abraham, 2006). Since ground improvement is a principal practice domain of geotechnical engineers, it is important that geo-professionals play a role in addressing the sustainability for these projects. In this paper, we illustrate by case history how different materials and methods associated with deep mixing projects can impact overall project sustainability through quantifying project embodied energy (EE) and carbon dioxide (CO2) emissions. EE is defined as all energy consumed to bring something into its present state (Chau et al., 2008; Inui et al., 2011; Soga et al., 2011; Chau et al., 2012). Recommendations are then made for how adverse environmental impacts of Deep Mixing Methods (DMMs) may be minimized, leading to more sustainable geotechnical construction."

Jan 1, 2015

By William M. Tanner, Daniel C. Brahana

"A drilled pier foundation was originally designed to support the proposed G. Wayne Clough Undergraduate Learning Commons on the campus of Georgia Tech in Atlanta, GA. Reflective of the site geology, the original drilled pier foundation was divided into a Northern and Southern portion with an allowable end bearing capacity of 60 ksf and 100 ksf, respectively. After initial pricing on the original design, several value engineering options were submitted that featured changes to the original design capacity and construction method. The project team selected the value engineering option that involved conducting an Osterberg Load Cell test to assess end bearing of the site bedrock and skin friction. Results of the Osterberg Load Cell test justified increasing the allowable end bearing capacity of the site bedrock to 100 ksf in the Northern portion and 125 ksf in the Southern portion. Considering the final foundation design and Osterberg Load Cell test program, a net savings of approximately $259,000, or approximately 34%, was obtained over the original design.Project BackgroundThe G. Wayne Clough Undergraduate Learning Commons (CULC) is a 5-story academic building on the Georgia Tech campus in Atlanta, Georgia. The CULC was completed in 2011 and consists of a concrete frame structure supported on a drilled pier foundation.After pricing of the original drilled pier foundation design, several value engineering (VE) analyses were performed by the foundation contractor in an effort to demonstrate the potential for a reduced foundation cost. The VE analyses focused on variations in design assumptions, as well as construction techniques. This paper presents a case study that demonstrates how the value engineering process can be used to reduce foundation costs.Site Investigation and Subsurface ConditionsThe CULC building site is located within the Southern Piedmont Physiographic Province, an area underlain by metamorphic and igneous rocks. McConnell and Abrams (1984) indicate that the site is located at the boundary between two distinct geologic formations. The Northern portion of the site is underlain by the Wahoo Creek Formation while the Southern portion of the site is underlain by the Stonewall Formation. The following paragraphs briefly describe the geotechnical investigations performed by the project geotechnical engineer (GE) for the CULC."

Jan 1, 2015