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By Ørjan Nerland, Torgeir Haugen, Astri Eggen, Kjell Karlsrud

"Ground improvement by the deep dry mixing (DDM) method is used in Norway since the late 1970's. A brief review is given of the Norwegian guideline for ground improvement with DDM issued in 2012, but focus is on practical examples and experiences related to improving the stability of excavations and natural slopes in soft clays. Two examples deal with experiences from 10 to 18 m deep excavations in soft and partly highly sensitive clays, where DDM panels and block stabilization were used to both give sufficient stability against bottom heave and to limit lateral wall displacements. A third case deals with improving the stability of a natural slope in quick clay by installing DDM panels near the crest of the slope. To limit disturbance and excess pore pressures generated during the DDM works, vertical drains were installed in advance in between the DDM panels. This ensured that the excess pore pressures generated by the DDM works (up to 150 kPA) dissipated quickly, which was instrumental to avoid triggering a landslide during the stabilizing works.INTRODUCTIONThe lime column (LC) method developed in Sweden and Japan in the mid 1970's (e.g. Broms and Boman, 1977). Since then, there have been significant developments in Scandinavia and around the world in terms of rigs, mixing machinery and tools, and type of binders used. The method, presently named the ""Dry Deep Mixing"" (DDM) method in contrast to the wet deep mixing methods (WDM) that also have developed significantly over the past decades, e.g. Kitazume and Terashi (2013). The first application of the DDM method in Norway was in the late 1970's to improve the stability of an excavation in quick-clay, then using only lime as binder. Most DDM applications in Norway have also thereafter been to improve the stability of cuts, supported excavations or natural slopes in soft clays. The Norwegian Geotechnical Society (2012) issued in 2012 “Guidelines for design of ground improvement with DDM methods"". The following highlights design issues dealt with. The paper focuses however, on some practical cases where DDM has been used to improve stability of deep excavations and a natural slope in soft and partly highly sensitive clays."

Jan 1, 2015

By Jesus Gomez, Mary Nodine

Rigid inclusions are widely used in the U.S. as a ground improvement tech- nique, particularly for industrial, low- rise and highway applications with poor subsurface conditions, where control of settlement is necessary. Rigid inclu- sions consist of grouted or concrete elements typically 12-24 in (305-610 mm) in diameter that may or may not be reinforced with a center bar. Typical soil conditions where rigid inclusions are feasible might consist of a surface layer of fill and natural, granular soil, followed by a stratum of soft silt or clay overlying a dense or stiff formation. Rigid inclusions are installed from the existing ground surface or suitable work platform, through the surface soils and through the soft, compressible layer, and into the deeper layer, which is less susceptible to compression- induced settlement. Typically, when used to support an extended area surcharge, the inclusions are installed in a rectangular or triangular pattern at regular spacings ranging from 5-12 ft (1.54 m), depending on a variety of factors. The rigid inclusion system is often capped with a load transfer platform (LTP), whose function is to direct a significant portion of the applied load toward the rigid inclu- sions. Additional load is transferred to the rigid inclusions through the upper fill soils above the compressible layer. The rigid inclusions transfer the applied load axially to their tips and into the deeper layer. In the U.S., rigid inclusions are mostly installed using displacement auger systems. The use of a dis- placement auger has significant advantages. It produces zero to near- zero spoils, which is an important environmental consideration. The

May 1, 2023

"Full time inspection of drilled shafts by qualified personnel is a necessary part of construction. Detailed inspection procedures for routine inspection are provided in the Drilled Shaft Inspector’s Manual, published jointly by the DFI and ADSC: the International Association of Drilled Shaft Contractors.The use of NDT methods or other observation methods, such as probes, video camera inspection, remote shaft wall inspection devices or various calipers are not suitable substitutes for routine "topside" construction inspection as described in the Drilled Shaft Inspector’s Manual. However, these NDT and other "remote" or indirect observation methods are valuable alternatives to direct entry of personnel into drilled shaft excavations. They should be considered whenever appropriate to reduce the risks of direct entry of personnel into drilled shaft excavations.As described in the Drilled Shaft Inspector’s Manual, observations made during construction are essential for quality construction of drilled shafts. The shaft depth, diameter, plumbness, bottom conditions, reinforcement, concrete continuity, and bearing conditions are most easily checked during construction. Some of these observation methods include excavation around the shaft for relatively shallow inspection, down-hole inspection for end bearing conditions or rock sockets, and video camera devices for remote inspection. In rare circumstances, a drilled shaft can be extracted for inspection. Before concrete placement, the bottom of the shaft can also be probed by drilling or coring to determine if there are voids or soft zones in the material at the base of the shaft.The Drilled Shaft Inspector’s Manual focuses on traditional "topside" inspection for routine drilled shaft construction."

Jan 1, 2004

By M. Meckkey El Sharnouby

In this paper, the results of full-scale field testing of reinforced helical pulldown micropiles (RG-HSP) installed in clayey till soils and resting on sandy soils are presented. Piles were tested under monotonic and two way cyclic lateral loadings. Effect of different loading setups on the results is demonstrated. The factors affecting the piles' performance are discussed. It was found that under monotonic loading the piles were able to sustain displacement up to 50% of the grout shaft diameter. Under low cyclic loading levels, the piles did not suffer degradation in the performance. Also, the degradation rate during cyclic loading increased with the increase of the load level. The experimental results show that the reinforced helical pulldown micropile is a reliable foundation option for lateral monotonic and cyclic loading applications.

Jan 1, 2011

By Anne Lemnitzer

Experimental data are the cornerstone of scientific research, providing empirical evidence to validate hypotheses, test theories, inform decision-making and help develop innovative design and analysis methods. However, beyond traditional empirical validations, experimental data have also become the most crucial component of AI algorithms, measuring the algorithms' effectiveness, and allowing engineers to ensure their reliability and applicability. The DFI "Rock Socket Project," awarded in the spring of 2018 allowed for the indispensable, experimental data-based validation of structural shear magnitudes, which have been hypothesized and discussed for years within the deep foundations community and cautiously approached by many design engineers. The fundamental project idea, i.e., the investi- gation of pile shear magnitudes through experimental research, was sparked during a heated discussion in the October 2016 Drilled Shaft Committee meeting in New York. Should we design for amplified shear at the rock socket of a drilled shaft or is this merely an artifact of the p-y design approach? Data were needed to provide consensus.

Nov 1, 2023

By W. G. K. Fleming

Mr P. Bermingham introduced paper 9.1, describing the development and trials of a new pile load-testing technique that the Authors had termed "Statnamic". The system involved launching a test weight mounted on the head of the pile by igniting chemical fuel in a pressure combustion chamber between the pile head and the test weight. The expansion products from the burning fuel generated large pressures which were used to launch the weight upwards at high velocity. The reaction from this force generates an equal and opposite force at the pile head. This force is typically of much longer duration compared with, for instance, dynamic load testing by drop hammer. In addition the pile experiences a much lower acceleration - typically of less than one g. Because of the long duration blow, the pile is loaded at below its natural frequency and is therefore under a uniform high stress over its full length throughout the duration of the test. The pile behaviour is not dominated by the complex action of an impulsive stress-wave as with standard dynamic testing. The test technique is thus essentially quasi-static. It was anticipated that a ram test weight of 16 tonne would be sufficient to provide the test reaction for a 600 tonne load test. It was pointed out that the device was still at the research stage, but had yielded encouraging results to date. Testing would proceed from model testing and computer simulation to full scale field testing.

Jan 1, 1991

By Norm Kirk, Robert Bittner

"The addition of a new powerhouse at the existing Tulloch Hydroelectric site on the Stanislaus River in the western foothills of the Sierras Nevada Mountains of central California required a deep excavation in rock on the downstream face of the dam. A cofferdam (water exclusion device) was necessary to isolate the powerhouse construction site excavation from the existing Goodwin Reservoir and the turbulent discharge from the existing powerhouse. The cofferdam was positioned on a steeply sloping fractured rock surface exceeding 50 degrees.This paper describes the challenges encountered during design and construction of the cofferdam and describes the unique design features used to address these challenges including:•,The use of flat-sheet-piles to form cellular walls on the steeply sloping rock surface.•,The use of 5-ft deep tremie concrete plugs in the bottom of the sheet pocket cells to create the bottom seal of the cellular cofferdam walls against the sloping rock surface.•,The use of vertical post-tensioned rock anchors to provide shear resistance at the contact point between the base of the cellular-wall and the sloping rocksurface.INTRODUCTIONModification or expansion of existing hydroelectric power plants often require downstream cofferdams or water exclusion devices to temporarily separate new construction from turbulent downstream discharge of the existing dam. Most dams are positioned on solid rock in the narrowest and therefore the steepest section of the river. This combination of steeply slopingrock and the need for an exclusion barrier creates a challenge for the design engineer trying to maintain a safe dewatered construction site. Typical cofferdam solutions for hydroelectric dams usually use large granular filled circular sheet pile cells that perform as gravity structures. However, this type of structures is not well suited to steeply-sloping highly irregular rock surfaces in a confined area."

Jan 1, 2017

By M. Hesham El Naggar, Tony Sangiuliano, Alper Turan

"Bridge abutments supported on pile foundations are often constructed over weak and compressible soils. The consolidation settlements induced by the embankment loads are known to result in downdrag and lateral forces on the piles supporting the bridge abutments. The performance of a pile group including inclined piles embedded in consolidating soils was investigated numerically considering surcharge loads from approach embankment construction. A two-dimensional numerical model was constructed using commercial finite element software PLAXIS and calibrated against field measurements of the abutment movements observed on Brookdale Avenue Underpass Structure located on the Macdonald-Cartier Freeway in Ontario between Cornwall and the Quebec border. The soft soil model (SSM) was used to simulate the constitutive behavior of the compressible soil deposit. The SSM model parameters were determined based on the laboratory tests. Subsequently, time dependant development of downdrag effects was comparatively evaluated for vertical and inclined single piles as well as a pile group that included both vertical and inclined piles.Results showed that drag loads increased with the consolidation time. However, majority of accumulation of drag loads took place within first 120 days after installation of piles. The results also indicated that the shear forces and bending moments are controlled by the lateral spreading of foundation soil and their accumulation is proportional to consolidation time. The large axial strains caused by large downdrag forces are considered to have yielded the piles and this is a possible reason for unusual abutment movements. The results presented in this study are considered to be of interest to researchers and practitioners.1. IntroductionDeep foundation units are widely used for supporting bridge piers and abutments, where weaker surficial soils preclude shallow foundations. Particularly in Ontario, semi-integral and integral abutment bridges are typically supported on end-bearing steel driven piles. The construction of approach embankments over weaker, compressible soils results in significant vertical and lateral soil movements, which induce additional loads on piles supporting the abutments. In order to minimize such effects, preloading and surcharging are commonly employed approaches to avoid unanticipated settlements prior to the installation of piles. Other alternatives such as aggregate pier supported approach embankment are also being studied as the schedule restrictions imposed by preloading and surcharging becomes cost prohibitive (Turan et al. 2012)."

Jan 1, 2015

By Jacob A. Jordan, Rachel M. Garrett, W. Robert Thompson III, James C. Pegues

"Environmental control structures for an existing fossil-fuel power generating plant near Pascagoula, Mississippi faced several design and construction challenges due to space limitations. Conceptual design calculations indicated drilled shaft foundations would likely be needed to accommodate the higher lateral and compressive loads expected under some structures. A maximum drilled shaft diameter of 60-in was preferred due to various space constraints. Smaller diameter drilled shafts were deemed acceptable under structures with more moderate loading conditions. Furthermore, augercast piles were considered where lateral loading was not a governing design criterion.A series of SPT borings and CPT soundings revealed a subsurface profile consisting of soft to firm clays to depths of about 25 feet, underlain by fine to coarse sands. The apparent relative density of the sands was loose just below the clay, with increasing density noted with an increase in depth.Analysis of conventional drilled shafts indicated needed capacities could not be achieved unless shaft lengths exceeded 100 feet. Post-grouted drilled shafts were therefore evaluated to decrease shaft lengths by taking advantage of increased base capacity. Analyses showed the higher predicted capacities needed for some structures could be achieved with this approach. Final design for the project incorporated 90-ft long, 60-in diameter post-grouted drilled shafts; 60-ft long, 48-in diameter post-grouted drilled shafts; and 60-ft long, 48-in diameter conventional shafts. Both post-grouted and conventional trial shafts were installed as part of the detailed design phase of the project. Each trial shaft included CSL integrity testing and Osterberg-cell bi-directional load testing. Load test results revealed that additional base capacity was, in fact, achieved through the post grouting process. The 60-in diameter post-grouted production shafts and the 48-in diameter conventional production shafts have been installed at the site, with the project that would utilize the 48-in diameter post-grouted shafts deferred at this time."

Jan 1, 2015

By I. D. Dayal, Anil Kumar Jain

"Cutoff walls are frequently used to slow down or prevent seepage of water through and/or around dams. Cutoff wall is a type of seepage barrier structure designed to reduce the flow of water underneath temporary or main dam. There are number of techniques for the construction of cutoff walls including concrete, Jet grouting and permeation grouting. NHPC LTD, a premier Govt. of India undertaking has been instrumental in the hydropower development within the country & in nearby countries like Nepal & Bhutan since last four decades. NHPC LTD has completed more than 20 hydro-electric projects with total installed capacity of 6587MW (including capacity addition by JV- NHDC). In all these projects, different types of dams and spillways were constructed in not so benign to extreme challenging geological set up. There has always been challenge associated with the temporary diversion works. The project sites sometimes incur huge river bed excavations in case of concrete gravity dam founded on rock foundation at large depth. The challenges for minimizing the seepage have been well taken care by constructing the dedicated seepage barriers. The construction of cut-off walls have progressed from “conventional continuous trench backfilled with conventional concrete or plastic concrete” to “grout curtain”, to “jet grouting” to the “concrete cut-off wall” , the last being the most sophisticated & credible seepage barrier.The efficiency of the cut-off walls are monitored by the seepage quantity observed (reduction of the seepage flow), uplift pressures or exit gradients after construction of cut-off walls. For construction of the main concrete dam, required space is created by the river bed excavation for placing the dam foundation on sound rock. Sometimes there is deep river bed excavation from 30 to 40 m depth or even more as per the available rock profile. Temporary coffer dams are constructed for diverting the river flow through diversion tunnels / channels etc. In deep river bed excavation; there are high chances of the significant seepage through the coffer dam foundation / river bed material due to high hydraulic gradients. Seepage and piping are the main causes of the failure / damage of the temporary coffer dams. If the seepage quantity is too high, then it becomes difficult to handle it by dewatering in the dam pit. Dam concrete is required to be placed unhindered to have a monolithic construction of dam blocks & to have faster construction in the working season. Cut-off walls increase the seepage path considerably thus reducing the exit gradient and further reduction of the seepage thus helping in maintaining the seepage free area for working."

Jan 1, 2016

By Daniel Stevenson, Richard Guenther

"The preservation of historic buildings is not only essential to the understanding of our national heritage, but it is also environmentally responsible to adapt existing buildings to compatible new uses. With this perspective, the American Enterprise Institute began exploring options to expand the newly acquired Andrew Mellon Building, located at 1785 Massachusetts Ave. NW in Washington, D.C., without causing any harm to the Beaux Arts style limestone façade and its plaster interiors. The building is a National Historical Landmark, but its 72,000 sq ft (6,690 sq m) of usable floor space did not meet the needs of its new owner. The building perimeter is very near the property line, so horizontal expansion was not possible. Adding height to the building was not an option, as this would have altered the historic nature of the building exterior. The only feasible option that could provide the desired floor space was to add a new floor underneath the existing structure. By adding a level beneath the existing building, an additional 28,000 sq ft (2,601 sq m) of floor space could be produced.Berkel & Company Contractors was chosen as the deep foundation/shoring contractor tasked with ensuring that the existing structure was stable and remained undamaged during the excavation and construction of the new lower level. To accomplish this, Berkel provided a shoring system that would act as both excavation support and permanent deep foundation elements for the final structure.Preservation of the existing limestone façade and plaster interiors was critical to the success of the project, as additional foundation settlements could damage these irreplaceable building components. Project specifications, therefore, included very stringent limits for foundation settlements. The maximum allowable total settlement for all existing building walls and columns was ¼ in (6 mm) for the duration of the project."

Jan 1, 2017

By David S. Graham, Joseph D. Bailey, Paul J. Axtell, Michael K. Muchard

"Two instrumented test piles were simultaneously subjected to a static lateral load test by jacking the piles apart. One of the piles was loaded in axial compression via kentledge during the lateral load test. Both piles were constructed in an identical manner. These piles were constructed and tested as part of a construction-phase load test program for a floodwall improvement project along the Missouri River in Kansas City, Kansas. Details of the subsurface conditions, drilled pile construction, instrumentation, and load testing procedures are described. Data collected during testing of the piles are presented and compared. Potential effects of the axial compressive load related to observed differences in pile lateral response are discussed.INTRODUCTIONTwo instrumented test piles were simultaneously subjected to a static lateral load with one of the piles also subject to a combined axial load during testing. The load test program was part of a floodwall improvement project in Kansas City, Kansas. Known as the BPU floodwall, the floodwall runs along the south bank of the Missouri River at a Kansas City Board of Public Utilities power generation and water treatment facility. The project location is shown in Fig. 1.Drilled, 2-ft (610-mm) diameter piles were designated by the designer, the U.S. Army Corps of Engineers (COE), as the foundation type for supporting extended floodwall footings. The drilled piles are fully cased, cast-in-place concrete, reinforced with a steel 12x74 (310x110) H-pile. In order to test soil lateral response and pile structural response under combined loading, the COE required that both a lateral test and combined lateral and axial test pile be constructed and tested. In order to most efficiently test both piles and to allow for simpler comparison, the two piles were simultaneously laterally loaded by jacking the piles apart, applying a maximum lateral load of 195 kips (867 kN). A constant axial load was applied to the combined test pile by kentledge prior to lateral loading and was maintained for the duration of the lateral load test. The total weight of the kentledge was 61.5 kips (274 kN). Fig. 2 shows the test setup."

Jan 1, 2017

By Timothy C. Siegel, Paul J. Axtell

The Missouri Department of Transportation (MoDOT) recently replaced the Hurricane Deck Bridge that carries Highway 5 traffic across the Osage Arm of the Lake of the Ozarks in Camden County, Missouri. The former bridge was constructed in the 1920's and was supported on pneumatic caissons bearing on dolostone bedrock. The replacement structure is founded on drilled shafts socketed into the bedrock. During the design phase of this bid-build project, a baseline design was developed and Alternative Technical Concepts (ATC's) were allowed from approved contractors. Those ATC's were confidential and not shared between teams. Either the baseline design or the approved ATC design could be bid by the respective contractors. The baseline design included re-use of the 90-year old caisson foundations. Accordingly, an extensive evaluation of the caissons and underlying bedrock were conducted by coring, laboratory testing, acoustic tele-viewer (ATV), and cross-hole sonic logging (CSL) methods. The results of the investigation indicated the caissons were in excellent condition and suitable for re-use. However, a more cost-effective ATC was submitted, awarded, and constructed that did not re-use the existing caisson foundations but rather reduced the span lengths, increased the number of piers in the water, and supported those piers on drilled shafts. Interestingly, the difference in low bid price between the awarded ATC and the baseline design was less than one percent of the construction cost. This paper describes the multiple foundation designs that were necessary for this interesting project. The various foundation evaluations include the existing pneumatic caissons, large-diameter open-ended pipe piles to support the baseline design, and the design of rock-socketed drilled shafts that were successfully constructed in 2012.

Jan 1, 2017

By Rodrigue Karam

An assessment of the geotechnical conditions at the Manhattan Cruise Terminals (Piers 88, 90, 92 & 94) was conducted after excessive settlement and structural distress was reported at Pier 92. The piers are located on the Hudson River along the west side of Manhattan, New York. The following paper focuses on the investigation and analysis performed on Pier 88 located at the western terminus of 48th Street. The pier is supported by approximately 2,500 timber piles bearing on soft organic silts and clays. The first portion of the analysis consisted of an offshore field investigation and laboratory testing to classify the subsurface soils within the project area and estimate the geotechnical capacities of the timber piles. Additionally, a settlement analysis including consolidation and negative skin friction analyses was performed to evaluate existing settlement levels. Axial and lateral analyses were performed to develop the soil springs (p-y, t-z, and q-z curves) necessary for the structural analysis.

By John Erikson, Alan J. Lutenegger, Nicholas Williams

"In order to evaluate the level of disturbance produced in clays during installation, a series of single-helix and multi-helix anchors were installed at a test site consisting of a stiff overconsolidated clay crust overlying softer near normally consolidated clay. Field vane tests were then conducted over the top of the helical plates at various depths to determine the undrained shear strength after installation and were compared with undrained shear strength measured in adjacent undisturbed ground. The tests represent the first time that the degree of installation disturbance has been evaluated directly and show that even with perfect installation practice the clay is disturbed as a result of rotation of the helices during installation. The results show that the soil is not completely remolded but that the strength is below the peak undrained strength of the adjacent undisturbed ground. Measurement of the installation torque and the rate of advance are used to define an “Installation Disturbance Factor” which may help to evaluate the quality of the installation by the Contractor and degree of soil disturbance. INTRODUCTIONAn important consideration in the design of Helical Anchors is the degree of disturbance to the soil during installation. This may be especially important for saturated fine-grained soils where the disturbance from installation may produce a reduction of the undrained shear strength. Even though this was recognized as early as 1950 by Skempton, soil disturbance is often ignored by engineers using current design procedures. Field investigations were performed to obtain both directs and indirect evaluation of the degree of disturbance produced by the installation of single-helix and multi-helix anchors in clay and the influence of disturbance on behavior. The investigations involved measurement of torque and advance during installation, load tests performed to determine load-displacement behavior and ultimate capacity and field vane tests performed over the helical anchors to evaluate changes in undrained shear strength as compared to adjacent undisturbed ground. The characteristics of the site and details of the installation are presented. Results of the field vane tests are shown for a number of helical anchor installations and results of load tests are presented. The results indicate that a reduction should be made to the undisturbed undrained shear strength for design and that the reduction may be related to the Sensitivity of the clay and quality of installation."

Jan 1, 2017

By Adel M. Hanna, Ibrahim M. Mashhour

"Collapsible soil is known as one of the difficult soils, which possesses considerable strength when it is dry and significantly reduced when inundated. In practice, in case of a thick layer, pile foundations are often used to penetrate the collapsible soil to firm soil/rock strata. Inundation of collapsible soil is accompanied by a large and sudden settlement, which may significantly increase the negative skin friction and accordingly the drag loads on the pile’s shaft. Inundation may take place from the running surface-water or raising the groundwater. In case of surface water, the amount of settlement varies, depending on the extent of the wetted zone and the degree of saturation in the soil, while rising groundwater will produce full saturation in the ground and accordingly larger settlement.In the literature, there is lack of reports dealing with the prediction of the drag load on piles in collapsible soils subjected to inundation. This is due to the complexity of modeling collapsible soil analytically. Alternatively; the results of a sophisticated experimental investigation may guide the researcher to develop a model to predict the drag load on these piles.This paper presents the results of a small-scale experimental investigation tailored to measure the soil collapse during inundation and the associated drag load on an endbearing pile’s shaft. Based on the results of the present investigation, the effect of the soil collapse potential and the pressure acting on the soil during inundation on negative skin friction is presented.INTRODUCTIONCollapsible soil is a metastable material, traditionally defined as unsaturated soils that experiences a radical rearrangement of particles and significant reduction of volume upon wetting with or without loading (Bara 1976; Houston et al., 1988). A wide range of soils fall into the category of collapsible soil, including naturally existing types of soils such as: Alluvial flood plains, mud flows, residual soils, colluvial deposits, fans, aeolian or wind-blow deposits sands and silts (loess), volcanic tuffs, gypsum, dispersive clays, loose cemented sands , sodium rich montmorillonite clays (Clemence and Finbarr 1981).Soil wetting and soil saturation may take place as a result of urbanization or natural causes, such as: groundwater level rise, landscape irrigation, broken water pipelines or sewer lines, poor surface drainage, groundwater recharge, cut/fill construction, and moisture increase due to capillary rise. The severity of the outcome depends heavily on the so called collapse potential of the soil, which depends mainly on; soil type, compaction effort, initial water content and stress level at soaking (Houston and Houston, 1997; Ayadat and Hanna, 2007)."

Jan 1, 2015

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 R. K. Filip

"Steel bearing piles have long been used to carry high compressive, tensile and lateral loads. Such piles are most commonly tubular or ""H"" profile and are typically installed using percussive techniques. The noise and vibration associated with such installation techniques tends to preclude the use of steel bearing piles in urban and other sensitive areas.This paper describes the design and construction of an innovative new road bridge in Milton Keynes, UK. The steel bearing piles were required to continue out of the ground to form the bridge columns and abutments and then be cast directly into the soffit of the reinforced concrete bridge deck. This project was to be the first time in the UK, that this form of bridge design had been used.The paper shows how new installation techniques allowed the designers to use these high capacity steel elements in a sensitive urban environment without the use of percussive or vibratory installation techniques. Finally the paper shows how these quiet and vibration-less installation techniques can be extended to other applications.A UNIQUE BRIDGE SUPPORTED ON ""BOXED SHEET PILES""CONCEPT HISTORYThere are over 700 bridges in Milton Keynes. Concrete is the dominant construction material, most are single span with massive parallel wing wall retaining abutments. All have a certain uniformity of aesthetic design. Pell Frischmann Consultants Ltd (PFC) proposed to the client, English Partnerships (EP), that an ""integral bridge"" with a slender open appearance would be an appropriate aesthetic form for a new highways bridge, within the district of Westcroft (figure 1). The concept required that the bearing piles be continued up out of the ground to form the bridge columns and abutments. Four rows with four piles in each row were suggested. Each would then be cast directly into the reinforced concrete bridge deck forming a moment connection (figure 2). This concept meant that a single continuous steel structural member would replace traditional reinforced concrete bored piles, pile caps and piers. This member would carry vertical and lateral loads. The conceptual design was intended to meet the following client requirements:"

Jan 1, 2005

By João Veludo, Eduardo Júlio, Helen D. Robinson, Jesús E. Gómez

"Utilization of micropiles for structural retrofit requires connection of the micropiles to the footings of the existing structure. Almost ten years ago, an experimental research effort was carried out in the US to investigate the magnitude and mechanism of development of the bond strength between micropiles and existing concrete. The study resulted in important conclusions on the mechanism of connection capacity development and provided specific recommendations for practical design of micropile-to-footing connections. In the last five years, the original study was complemented by an intensive experimental effort in Portugal aimed at answering many of the questions still remaining on this topic. This paper is a summary of the knowledge that is presently available on the capacity of micropile-to-existing footing connections. It presents the results and observations of model tests performed in the US and Portugal, as well as some tests from actual construction sites. The paper presents clear evidence that friction may be the most important component of connection capacity. It also presents a clear correlation between confinement and connection capacity.IntroductionUtilization of micropiles for structural retrofit requires connection of the micropiles to the footings of the existing structure. This is often accomplished by drilling through the footing and developing the connection by direct bond between the micropile grout and the existing concrete. Almost ten years ago, an experimental research effort was carried out in the US to investigate the magnitude and mechanism of development of the bond strength between micropiles and existing concrete. Smooth and textured micropile inserts of varying lengths were tested to failure inside pre-drilled holes of varying diameters. That investigation led to several publications (Gomez et al. 2005, Wilder et al. 2005, Cadden 2009) on the mechanism of development of bond strength between micropiles and concrete, which included a chart for preliminary bond value selection depending on the diameter of the hole and texture of the micropile.An intensive testing program was carried out in Portugal in the last five years. The program focused on answering questions posed by the original investigation and on finding the relationship between connection capacity and level of confinement. Both investigations, and especially the testing performed in Portugal, provided an invaluable amount of information on the mechanisms of failure of micropile-to-footing connections. This information should be the basis for development of design procedures that, until now, were not available."

Jan 1, 2015

By Serhat Baycan, Mikias Yohannes

"Kuala Lumpur Karst is a complex limestone formation that is characterized by presence of cavities, solution channels, pinnacles and floaters. Basement excavations in such geological formations are usually challenging, mainly owing to the unpredictable rock head depths and potential for groundwater inflow. Any excavation support system should have adequate robustness and water tightness. Traditionally, Secant Bored Pile walls (SBP) with struts are the preferred option for karst ground. This paper discusses a cost effective and innovative alternative solution for a particular site – using Deep Soil Mixing (DSM) and using Contiguous Bored Piles (CBP) together with Ground Anchors (GA). The site, located around one of the busiest areas of Kuala Lumpur, is a 5,700 m2 commercial and residential development. A 16.0 m deep excavation was needed for four levels of basement and excavation support along the 275 m perimeter of the development. Within the site, the depth to rock head varied from 6 m to 19 m. The basis for each solution and conditions for its suitability are discussed in detail. Some design considerations and construction challenges are also presented. The performance of the two retention systems during excavation are presented, together with comparisons versus design predictions. Suggestions for future development are also given. Advantages of this approach compared to other traditional approaches are highlighted.1. INTRODUCTIONThe geology of Kuala Lumpur is among the most complicated and geotechnically challenging formations in South East Asia. The majority of the city falls into the Kuala Lumpur Limestone formation; which is a thick, highly-weathered and cavernous limestone. This formation is pure calcitic to dolomitic in composition, having infrequent schist and phyllite interbedding (Gobbett et al., 1973).The KL limestone has a highly karstic topography dotted with cavities, ravines, interconnected subterranean channels, pinnacles, overhangs, floaters and slump zones (Tan, 2006). This results in erratic bedrock profiles even within short distances. It is not uncommon to see a precipitous rock head incidence within short distances in the same site. In most parts of the City, the bedrock is typically encountered ranging from very shallow depths to about 30.0 m. The exception to this is at the heart of the City, where Kenny Hill formation prevails above the KL limestone. In such cases the limestone bedrock can be encountered much deeper. The erratic rock head profile and the highly karstic nature of the KL limestone makes it a geotechnical challenge requiring careful consideration of suitable engineering solutions.1.1 – Site DescriptionThe site, located in downtown Kuala Lumpur, is abutted by a busy street on the North. Before development, the site previously served as a car park. To the west an access road separates the site from an empty lot; while on the east, the lot is bounded by light weight residential and commercial buildings. On the south side, the site is bordered by a road that separates it from a prominent Shopping Mall in the City. A layout plan and an artist’s impression of the finished development is shown in Figure 1."

Jan 1, 1900