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By Tony Suckling

"As we head toward the United Nations Climate Change Conference in Copenhagen in December, the environment and sustainability will become headline news for a while. Governments are expected to agree to a set of binding targets to reduce carbon emissions probably before 2020, and certainly before 2050. This will, in effect, initiate a low carbon economy in many parts of the world. Sustainability has mainly been rhetoric so far, the exceptions being projects for those looking to the long-term future and not for short-term financial gains.The probabilities and consequences of negative impacts on the environment and on society over the short term and in the long term can be assessed and mitigated, but mitigation often adds cost. Also, we cannot know what technologies will be available, say 1,000 years into the future, which is about 40 generations of our society. It is easier to have a connection with 100 years into the future, which is only about 4 generations. Individuals may have a different sense of sustainability, and place a different value on mitigation, its cost, its importance and its potential impacts.Sustainability means different things to different parties on a construction project. For example, a land developer is likely to have a different view on the design in terms of sustainability than that of the designer. The developer may also likely to be more interested in sustainabiliy if there are tangible economic benefits that might accrue. Achieving sustainability on any project, leads to conflict between competing interests or demands cooperation between the economic and technical sectors involved. The foundations for a building or bridge, by definition, need to interact with the ground whose behaviour cannot be dictated by man. The aims of sustainability are the same as for the building or bridge, both of which are constructed of manmade materials, but it is less clear how they should be achieved. An example is the driven pile that does not produce spoil waste, but is likely to be too noisy to be acceptable in an urban environment. This then begs the question, should the public accept the nuisance of short-term pile driving to achieve a more sustainable foundation? Additionally, the question has to be asked, can the deep foundations industry develop its techniques and products to help make them more acceptable and appropriate more often than is possible now?"

Jan 1, 2009

By Dennis Wrixon

It was a little bit exceeded. The decision was the uniform settlement is measured at each one corner and the highest one corner is the important one. And in addition there is a differential settlement of 2.1 mm allowed. So we reached about 7.8 or 7.9 mm with the highest corner and in addition 2.1 so it was a little too much. But behind there is a very difficult calculation of the authorities where all of the displacements are combined together and there are of course some more factors of safety in these settlements.

Feb 10, 2003

By A. R. Katti

The stone columns are widely used in the improving the bearing capacity of weak soils mostly for supporting flexible foundation systems. The load carrying capacity of a stone column is complex in nature. The load capacity is derived from the lateral stresses acting on the stone column due to load transmitted from the flexible structure due to deformation to soil mass and which in turn transmits lateral pressure in s3 direction. The load capacity is also function of the f value of the stone column, cohesion of the surrounding soil, K0 and Gb2 of surround­ing soil including passive resistance developed to lateral deformation of the stone column. The assessment of axial and radial deformation is much more complex. Recently Katti et.al. have developed a method based on a granular heap approach and computed with equivalent fe. which combines the effect of s3a and equivalent volume concept to estimate radial and axial strains. In this paper an attempt is made to put forward guidelines for design of stone column accounting for both stability with respect to shear and also with respect to settlement. The estimate of settlement are based on the internal properties of stone column and surrounding soil. It is considered thus the settlements computed are more realistic.

Jan 1, 1996

By Reinaldo J. Villa, Joshua C. Adams

The I-395/SR-836/I-95 reconstruction project is an $818-million design-build construction effort that includes construction of viaduct, segmental and signature bridges in Miami leading into Miami Beach in Florida. Based on the load testing performed during the design phase, the design-build team determined that conventional driven pile and drilled shaft foundations were not feasible for support of segmental and signature bridges. Due to the weak limestone formation and successful use of auger cast-in-place (ACIP) piles in the Downtown Miami area on commercial developments, ACIP piles were selected as a foundation system to support bridges. This is the first time in history where the bridges will be supported by ACIP pile foundations in an interstate highway in the State of Florida. The design build-team worked closely with the Florida Department of Transportation to develop requirements for the load test program. The paper will provide an overview of the geotechnical data collected, results of dynamic/bi-directional load testing performed on test piles, data collected, installation of piles, and lessons learned. The load test program included a total of fifteen test piles with dynamic, bi-directional, and lateral load testing on 30 and 36-inch diameter ACIP piles and instrumented with thermal integrity profiling wires.

Sep 8, 2021

By Paul J. Sabatini, Robert C. Bachus, Terence P. Holman, Panos Andonyadis

A recent landslide comprising approximately 12 acres (4.86 hectare) and a displaced volume of more than 500,000 cy (382,000 m3) caused the shutdown of a four-lane state highway and two high-capacity freight railway lines. After completion of immediate landslide stabilization activities, various long-term slope stabilization measures were implemented that focused primarily on gradual slope unloading in areas near and upslope from the scarp of the landslide. Near the completion of the upslope excavation, an anchored soldier beam and lagging wall was constructed to allow for the temporary unloading of the toe of the main landslide area to facilitate installation of a permanent underdrain. The design of the anchored wall utilized information collected during the rehabilitation construction and included inclinometer data, site survey results, piezometer data, and field construction observations. Using the history of site-specific movements, results of back-analysis calculations from the landslide, and geometry/performance of the post-construction slope configurations, the fully softened and residual shear strengths along two potentially critical sliding surfaces were calculated. Owing to the high confidence in the values of shear strength as afforded by this information, the confidence in local groundwater conditions, and control of the loads, the designers selected a relatively low, calculated short-term factor of safety (FS) (i.e., FS ˜ 1.1 to 1.2) for the most critical unloading step. Long term calculated FS values on the order of 1.2 to 1.3 were anticipated. This paper describes the detailed evaluation of the landslide slope movement data associated with the shallow and deep potentially critical failure surfaces and selection of the associated values of design shear strength for these potentially critical surfaces. A description is presented of the analyses and design of the anchored wall, measures implemented during construction to minimize slope movements, and post-construction monitoring results during the unloading and subsequent installation of the underdrain.

Jan 1, 2017

By Joseph T. Coe, Alireza Kordjazi, Michael Afanasiev

Cross-hole sonic logging (CSL) is a common quality assurance measure for the evaluation of the structural integrity of drilled shafts. The results of CSL can be supplemented by a set of tomographic images generated by cross-hole tomography (CT). Although the same access tubes, sources and receivers are used in both methods, CT has the advantage of providing a higher quality image of the possible anomalies in drilled shafts. Nevertheless, it has been reported in literature that the CSL and CT miss anomalies with sizes of smaller than 10 percent of the cross sectional area of the drilled shaft. This implies poor resolution despite the high-frequency of the stress waves utilized in these methods. This issue with resolution can be at least partially attributable to the fact that CT relies entirely on the inversion of the first time of arrival and ignores the information embedded in the rest of the recorded traces. This study examines the application of full waveform inversion (FWI) to generate a higher resolution image of the possible defects in drilled shafts from the same data used for cross-hole tomography. FWI is a wave-field method that aims to directly match the recorded traces with traces obtained from a numerical model of the domain. This has the benefit of avoiding the selection of the first time of arrival, along with increasing the resolution of the final image due to extracting more information out of the traces. Through a series of numerical simulations, synthetic traces were generated from a drilled shaft with defects of known mechanical properties, dimensions, and location. These traces were then inverted to evaluate the performance of FWI for structural integrity testing of the drilled shafts. INTRODUCTION The presence of construction defects can compromise the structural integrity of drilled shafts and negatively affect their performance (O’Neil 1991; Sarhan et al. 2002; O’Neil et al. 2003; Poulos 2005). Several non- destructive testing (NDT) methods exist that are currently used for the evaluation of the structural integrity of drilled shafts. Cross-hole sonic logging (CSL), cross-hole sonic tomography (CT), and thermal integrity profiling (TIP) are well-established and documented in the industry and practical manuals (Brown et al. 2010). NDT methods prevent the need for coring and excavation and are relatively fast and cost effective. Successful implementation of these techniques has also been reported in the literature (Branagan et al. 2000; Iskander et al. 2001; Mullin 2010; Johnson 2016).

Jan 1, 2019

By Zia Zafir

Design of the deep foundations for the loads imposed by lateral spread include the estimate of the pressure applied by the liquefied material as well as amount of anticipated displacement. In the absence of a non-liquefiable cover over a liquefiable layer, it is possible to design the foundation system just for the additional pressure applied by the flow slides. On the other hand, if a non-liquefiable layer exists above the liquefied zone, the foundation should be designed for anticipated movements. To completely account for liquefaction and/or lateral spread and their interaction with the deep foundation system, a coupled soil-structure interaction (SSI) analysis should be performed. However, a complete SSI analysis may not be feasible for most of the projects. This paper will present recent advances in analysis techniques and simplified methods to design deep foundations for liquefaction and lateral spreading. In addition, a case history of the Rancho California Bridge in southern California located within 1 km of the active Elsinore fault will be presented. One of the bridge abutments is underlain by potentially liquefiable layers. The pressure applied by the liquefiable layer was estimated to be greater than the shear capacity of the 36-inch CIDH piles designed for the abutment. However, with limited ground improvement and more careful analyses incorporating structural effects of CIDH piles, resulting design and construction resulted in a factor of safety greater than 1 against slope failure. The recommended approach was generally consistent with the recently published, and AASHTO sponsored, NCHRP 12-49 project regarding seismic design guidelines for new bridges and the effects of seismic displacements against bridge foundations.

Jan 1, 2006

By W. J. van Niekerk

Ballast Nedam is in Surinam constructing two bridges that will improve communications in the coastal region. The bridges will cross the Coppenam and Surinam rivers and will be founded on open-ended steel piles over 60 meters in length. The majority of piles are inclined and support prefabricated concrete girders forming the roadway. In most locations the stratum is consolidated cohesive layers extending to a depth in excess of 60 meters. For this reason, before pile driving operations commenced, it was decided that a number of test loads would be carried out determine the capacity of the piles. Loading tests were carried out on specially installed piles as well as on piles that would be used as working piles to support the structure. Working piles were dynamically tested using Pile Driving Analysis (PDA) equipment. This decision was based on the inclination of the piles, the cohesive nature of the soil and the increase of strength after the piles are driven. A good insight has been obtained into the real strength of the soil by comparing dynamic and static loading tests on vertical test piles. This made it possible to determine the required length of pile.

Jan 1, 2000

By Nagarajan. D, Raja Rajan. K, Vijayakumar. T

Major bridges crossing mighty rivers must be constructed in flowing water. Constructing the sub-structure in water has been a challenging job for contractor. Special construction techniques with marine fleets to be adopted for waterfront construction. Enabling works like temporary piling platform and cofferdam used for pile and pile cap construction. Apart from this, enabling works like load out jetty to transport the materials from land to water; temporary walkway for access of workman to work location; temporary access bridge for construction vehicles movement; temporary liners for tower crane foundation; Concrete block to act as dead man anchor for barge movements were all required by the contractor for smooth functioning of site as per construction schedule. Investment in enabling works by contractor plays a significant role on profit margin of the project and of course with utmost safety. Design of enabling works for waterfront structures involves hydrological data like afflux, bathymetry survey, current force, scour depth and wave force to be taken cautiously for safe and economic design. Type of foundation and pile/well cap top level corresponding to water levels shall influence the construction scheme. Usage of geotechnical software like Wallap and Plaxis required for enabling work design to enhance the safety of the structure. Bathymetry and soil condition play a critical role in design and construction of enabling works. Water Discharge quantity in river along with water levels like low water level, high flood level, seasonal fluctuation of water levels has a great impact on design of enabling works. Establishing enabling works for waterfront construction near to an existing bridge is an additional challenge for the contractor. Along with design, constructing the enabling works in water requires special construction methodology and sequence of work. This paper shall provide insights on overview of design and construction of enabling works for waterfront construction.

Nov 1, 2022

By Vijaya Bhushan Rao, Jason Redgers

The typical Vibrocompaction projects undertaken in the UAE are on reclaimed Sands. These Sands which are predominantly the crushable, calcareous, carbonate sands found locally as opposed to the more common quartz or silica sands that are featured in most design literature. The famous reclamations such as the iconic Palm Jumeirah in Dubai, often have specification for mitigation of liquefaction induced settlements, bearing capacity increases and total and differential settlement requirements. Often these performance targets are achieved by the means of achieving a particular relative density that are generally measured by a defined Cone Penetration Test, CPT targeting values of cone resistance (Qc), MPa at respective depth zones. In this paper some case studies are presented, where soil suitability for deep compaction by vibratory methods was firstly assessed for suitability using the Massarsch, 1991 compactability chart prior to the application of vibrocompaction and its subsequent evaluation. One such project named the Island Development required 17 to 23m depth of penetration only to treat the lower 5 to 6m of sand above rockhead as eventually the top 15m of sand will be further excavated to allow for the construction of basement. The paper will present pre and post CPT results, the results of initial site calibration trials and evaluation of the completed works.

Oct 1, 2022

By Keithe J. Merl, Brendan FitzPatrick, Gregg Piazza

Urban and industrial construction projects commonly involve interior work within buildings, warehouses and manufacturing facilities. Renovations of these existing structures must address both structural and geotechnical engineering challenges while also balancing the practicality of implementing solutions within site constraints including limited site access, overhead clearance restrictions, vibration tolerances and uninterrupted facility operations. This paper highlights two projects for an international shipping company where mezzanine level additions within active shipping facilities required construction of new foundations. Construction requirements included low vibration levels, as well as rapid and clean installation to limit impacts on the active shipping operations. The selected system also needed to adjust to both variable ground conditions and differing overhead clearances. This paper describes the installation, design and performance of Ductile Iron Piles used to meet the project challenges. The low vibration, driven pile system offered the ability to work within restricted overhead environments while successfully delivering working compression capacities ranging from 45 to 75 tons (41 to 68 tonnes) as well as lateral and tension resistance. The paper also presents the results of site-specific load testing (and pile capacity) for various termination criteria. INTRODUCTION Urban and industrial construction projects commonly involve interior work within buildings, warehouses and manufacturing facilities. Renovations of these existing structures must address both structural and geotechnical engineering challenges associated with the new construction. Foundation solutions must also balance the need to achieve design requirements with the practicality to be installed within the particular site constraints including limited site access, overhead clearance restrictions, vibration tolerances and uninterrupted facility operations.

Jan 1, 2019

By Sylvia S. Eskander, Sherif S. AbdelSalam, Mona B. Anwar

Expanded Polystyrene (EPS) geofoam has long been used in numerous geotechnical applications due to its lightweight and durability. Among these applications is the use of EPS as an alternative fill material to conventional roadway soil embankments. This study investigates the benefits of using EPS roadway embankments to reduce the induced stresses and strains on the underlying peat and soft clay. Firstly, mechanical and interface properties of the EPS were acquired from a companion study that also considered the cyclic loading and creep effects. In order to determine the actual stress-strain distribution within the EPS blocks, a physical prototype was developed in this study with overall dimensions of 1.2 x 1.0 x 0.5 m, with a density of 35 kg/m3. The prototype EPS blocks were subjected to cyclic loading with intensities ranging from 10 to 50 kN. Then, a numerical model was developed to simulate the behavior of EPS roadway embankments. The numerical model outcomes were verified against the prototype measurements. A parametric design study was also conducted to develop a correlation between EPS embankment height and the stress-strain that occur in the underlying strata. Results showed that EPS embankments could reduce stress and settlement in the underlying soil by about 40% and 54%, respectively. EPS APPLICATIONS AND BACKGROUND Expanded Polystyrene (EPS) geofoam blocks have been effectively used during the past several decades in numerous geotechnical applications. EPS static and dynamic properties as well as interface behavior were extensively characterized in various published studies such as that conducted by Horvath, 1994; Stark et al., 2004; Zarnani and Bathurst, 2008; Trandafir et al., 2010; Athanasopoulos et al., 2012; AbdelSalam and Azzam, 2016; and others. However, to be able to use locally produced EPS blocks, its physical and mechanical properties must be thoroughly determined. The lightweight and compressible material of EPS geofoam makes it suitable both as a backfill and for absorbing pressure in both the vertical and horizontal directions. Kim et al. (2010) adopted EPS as an alternative for soil backfill around buried pipes; their model showed a reduction in the vertical stress acting on the pipes by up to 36%. Oshati et al. (2012) presented a case study of a field-instrumented box culvert with EPS blocks on top, which reduced vertical stress by 58%. Meguid et al. (2017) used an EPS inclusion to surround culverts and achieved up to 72% stress reduction, depending on the EPS density and the culvert depth to width ratio. AbdelSalam et al. (2017) used a relatively thin EPS inclusion behind flexible cantilever retaining walls, verifying that the lateral pressure can be significantly reduced by 25%; they also developed a design chart for this application. Moreover, AbdelSalam et al. (2019) investigated the use of EPS as a lightweight alternative for soil backfill above shallow tunnels. It was found that EPS had created a differential movement between the wedge located above the tunnel and the neighboring soils, which accordingly reduced the vertical stress acting on the tunnel by 85%, due to the use of lightweight EPS material and positive soil arching.

Jan 1, 2019

By Filippo Maria Leoni, Alessandro Bertero, Gianluca Pianezze

"As part of the Southeast Louisiana (SELA) drainage program, designed by the U.S. Army Corps of Engineers (USACE) to reduce flood damages in the City of New Orleans and surrounding parishes through the construction of new pumping stations and better drainage canals, the SELA-22 project entailed the installation of a concrete covered canal along Jefferson Ave. and Prytania Street, in a highly urbanized portion of Uptown New Orleans, LA. The scope of the required soil improvement was to replace the soil between two parallel lines of sheet piles with a soil-cement mass to eliminate underseepage and provide structural support for the concrete culvert. The USACE selected the jet grouting (Jet Grout) technology for the construction of the bottom plug. The bottom plug is between 18 and 21.5 ft thick with a maximum depth of approximately 40 ft, for a total length of approximately one mile. The treated soil comprised soft clays and silts with occasional presence of sands. Project specifications required 100% area coverage, a 28-days unconfined compressive strength of 100 psi and hydraulic conductivity of 1x10-6 cm/s, to be verified by testing specimens from cored samples. The specialty geotechnical contractor proposed to accomplish the task utilizing their proprietary and innovative elliptical bi-fluid Jet Grout technology, and elected to perform a pre-construction bench scale laboratory mixing program to determine the most suitable grout mix features (i.e. binder type and proportions, binder content, etc.) to be applied in the subsequent field test and production stages. This paper will summarize and compare the results obtained from the different pre-construction and construction stages; interpretations of the data will be provided, along with general considerations regarding the effectiveness and significance of bench scale testing for jet grouting applications.INTRODUCTIONIn general, the effectiveness of the construction parameters in any ground improvement work depends largely on the physical and mechanical properties of the soil to be treated. Therefore, well designed laboratory and field test programs, aimed to disclose the interaction between the site-specific soils and the mixing parameters, are essential to achieve the desired end product."

Jan 1, 2016

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 Stefano Trevisani

Abstract The FIEC Sustainability Vision states that “risks should be identified and allocated in a fair manner across the project team from the early stages of the design phase. A partnering approach, where objectives and timescales are agreed in advance together with all relevant partners in the value chain, offers a useful solution to improve on site efficiency and reduce disputes”. An alliance or collaborative form of contract involving all parties is the best way to ensure fair contract conditions and proper risk allocation in construction projects. Collaborative contracts are particularly useful where there is uncertainty or undefined information or in the event of technical difficulties and other risks difficult to allocate among the parties involved in the project. Owners sometimes require even special output in terms of innovative technical solutions or special performance. In addition, this particular form of cooperation has been construed and developed with the intention of avoiding and mitigating another great risk associated with the construction industry (especially in complex projects): disputes and conflicts, which are often a major cause of delays, increased costs, loss of reputation and opportunities. In contrast, Alliances are a way to increase and strengthen business relationships, technical and economic innovation and effectiveness, in a worldwide global context where the waste of resources must be avoided in order to guarantee future recovery and growth. Of course, the total cost of a project is usually a key factor and the main driver for the Owner and the Contractors in deciding the type of relationship between them as well as the subsequent relationship with subcontractors and lower-tiers. This paper and presentation, will explain the main features and the principle benefits that the use of collaborative contracts can bring to all parties involved in the construction project, including the sustainable financial return that might be achieved if costly and time consuming disputes can be avoided.

Jan 1, 2014

By Alp Gokalp

The aim of this article is to present an application of jet grouting technique in stiff clays for foundations of the natural gas combined cycle power plant, under construction in Aliaga, Turkey. The plant site is in the Aegean coastal region and 60 km north of Izmir. The foundation soil is composed of quaternary alluviums on top and tuff base rock. The thickness of the alluvium varies between 16 m to 30 m. Groundwater was observed 2.5 m below the ground level. At the design stage, settlement analyses were carried out for the various buildings and facilities in the power plant. Based on the analyses, it was predicted that total and differential settlements are not tolerable, thus jet grouting is implemented as a ground improvement under the majority of the foundations of the power plant. This paper also describes the selection of jet grouting technique, application type and details of the process parameters such as injection pressure, number and size of nozzles, lifting and rotation speeds. Prior to the commencement of the jet grouting works, a number of preliminary parameter tests and preliminary pull-out tests were carried out throughout the site in order to define and verify the jet grouting process parameters to achieve the required diameter of 600 mm and minimum jet grout strength of 3.2 MPa. Moreover as part of the comprehensive quality control and quality assurance program pursued in the project, a number of tests; such as continuous coring, integrity testing, installation of confirmatory jet grout columns, were carried out during the production of jet grout columns.

Jan 1, 2002

By Brian T. Nereson, Michael C. Penney

"This technical paper was prepared to describe the general process by which the authors designed a column-supported load transfer platform (LTP) for support of asphalt-paved runway and taxiway embankment areas over soft organic soils, the major tasks and observations made during construction of the system, and the outcome of the system design and construction. The LTP system was designed using the method described in the BSI Standards Publication Code of Practice for Strengthened/Reinforced Soils and Other Fills, BS 8006-1:2010 (BS8006), to achieve performance objectives for the project. The design also used other criteria based upon the authors’ engineering experience and understanding of the expected interaction between soils, structures and geotextiles. The design and construction process described herein resulted in a successful project. The authors identified that full-time engineering oversight during construction was of high importance and provided a high degree of value to the project. The authors’ intimate knowledge of the potentially adverse effects of variations in construction practices promoted timely identification of construction deficiencies that could have affected the reliability of the system. This resulted in corrections and modifications being made, while materials were still accessible, to protect the intended performance of the finished system.INTRODUCTIONThe site is located in Marshfield, Massachusetts. The surrounding area is flat and contains significant wetlands with a water table at or near the ground surface. Prior to the improvements described herein, the site was already developed as an existing municipal airport with an approximately 3,000 linear-feet asphalt-paved runway oriented in a northeast/southwest direction (northeast end referred to as Runway 24 and southwest end referred to as Runway 6; Fig. 1). The site is located approximately 0.5 to 1 mile (Runway 24 and Runway 6, respectively) from the Atlantic Ocean.The improvement project included total extension of approximately 550 linear feet of asphalt-paved runways and taxiways over existing wetlands that consisted of soft, organic soils with varying but significant depths (Fig. 2). An initial geotechnical assessment performed for the project identified that the subsurface conditions were not suitable to support the proposed runways and taxiways in their existing state."

Jan 1, 2016

By James M. Tantalla, Roderic A. Ellman, W. Allen Marr, Scott R. Bamford

"Construction of the powerhouse for the Willow Island Hydroelectric Project required a 100-ft deep excavation inside the limits of a cofferdam and embankment-seepage cut-off wall through soil and rock adjacent to the Ohio River. Portions of the rock had preexisting weak plans and slickensided surfaces with low frictional strength. Stability analyses were performed for critical sections of the excavation to evaluate the stability of the soil slopes and rock cuts using buckling, tension crack, and limit equilibrium analysis techniques. Loading conditions included the 100-yr and intermediate floods, normal pool, sudden drawdown, and seismic design conditions.Stability analyses indicated adequate factors of safety for soil slopes and for rock cuts through the landside embankment sections. However, the results of deep-seated stability analyses through the rock supporting the riverside cellular cofferdam indicated unacceptable factors of safety. Consequently, the riverside portion of the excavation required measures to increase stability. Long, high-capacity rock anchors and deep dewatering wells to lower the site piezometric head were chosen for this purpose.Thirty high-capacity rock anchors were installed on the upstream, riverside, and downstream sides of the cofferdam rock cut. Required rock anchor loads varied from 1,968 to 2,074 kips. The designed anchors consisted of multiple, seven–wire strands with up to 59 strands per anchor. Bond lengths used an allowable bond stress of 100 psi based on the rock bond measured with pull-out tests. Maximum bond and anchor lengths were 50 ft and 140 ft, respectively. Measurements of forces in selected strands and displacements of the excavation showed excellent performance."

Jan 1, 2017

By Adrian Mercer, Ashkan Ameri

Due to general degradation, increased traffic levels, and historical ground movement, this road and rail bridge which provides an essential link between the interior of the country and the Port of Abidjan, required significant repair and reinforcement. This included strengthening the pre-stressed concrete box girders and replacement of the existing bored pile foundations. Replacement piles had to be adjacent to, and no longer than, the existing piles, in order to not compromise the stability of the operational bridge during the works. The underlying geology, however, meant that the pile loads had to be predominantly transferred into the ground through end bearing. Rather than installing a greater number of piles or larger diameter piles, innovative thinking changed the usual mind-set of designing the piles to the prevailing ground conditions, to designing the ground conditions to suit the piles. Jet grouted columns were installed beneath the toes of the new piles to increase the bearing capacity of the ground. This significantly contributed to the sustainability of the project and reduced carbon emissions through saving concrete, steel, plus transportation and disposal of spoil.

Sep 8, 2021

By Nicolas Denies, Jeroen de Leeuw, Bart Lameire, Jan Maertens, André Vervoort, Flip Hoefsloot, Noël Huybrechts, Flor De Cock

"In recent years, the Deep Mixing Method has increasingly been applied for the construction of earth and water retaining structures. From practice, it has been experienced that there is a real need to develop execution and design rules adapted to the function of the soil mix wall (retaining wall, water barrier, foundation solution or a combination) including the temporary or permanent character of the application. Based on the results of the BBRI Soil Mix project (2009-2013), a design approach has been developed in collaboration with the SBRCURnet. The present paper briefly discusses the principles of this design approach which takes into account the function of the soil mix wall and the characteristics of the soil mix material. The interaction between the soil mix material and the steel reinforcement can be considered in the calculations depending on the function of the soil mix wall. Design and quality control requirements are given in function of the application and take the lifetime of the structure into account. Durability aspects of the soil mix material are therefore considered in the present design approach.INTRODUCTIONSince several decades, the deep mixing method is used for ground improvement works. A more recent application is the use of soil mix as structural elements such as in the case of the earth-water retaining soil mix walls. Since 2000, due to the economic and environmental advantages of the method, this particular application has shown an amazing growth in Belgium and in the Netherlands. A typical excavation (16 m depth), realized with CSM (Cutter Soil Mix) panels, is shown in Fig. 1. For temporary applications, the questions related to the mechanical characteristics of the material, its permeability and its adherence with steel have been investigated with success within the framework of the BBRI Soil Mix project (2009- 2013) (see Denies et al. 2012 for more details). The durability of the soil mix material remains a complex topic while permanent applications are more and more observed in practice. In order to define an obvious design approach, it was necessary to clarify the potential functions of soil mix walls and to establish the requirements related to their design and construction. The BBRI (in Belgium) and SBRCURnet (in the Netherlands) have therefore worked together to publish guidelines in the form of a handbook titled ‘Soil Mix Walls’ (publication foreseen in 2015). In this handbook, a methodology is proposed for the design of the soil mix walls for which the interaction between steel and soil mix can possibly be taken into account dependent upon the application. Each potential function of the soil mix wall is described (e.g. earth retaining wall, cut-off wall, etc.) and the temporary or permanent character of the application is always considered."

Jan 1, 2015