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By K Ilamparuthi, R. K. Madhumathi

"This paper presents the results of 1g model tests conducted on model piles both single and two pile groups embedded in sand by physically inducing lateral soil movement. From the test results it was found that the pile with higher L/D ratio exhibits higher deflection in case of pile embedded in medium dense sand whereas in loose sand the response is vice versa with higher deflection for the pile of lesser L/D ratio. The induced bending moment in piles is more for longer piles than shorter piles irrespective of the density of sand bed. It is also found that the pile head deflection and the bending moment are found to decrease exponentially with increasing distance between the pile and the wall. For pile group arranged in a row parallel and perpendicular to retaining wall, the deflection of single pile is more than the deflection of two pile group irrespective of the depth of excavation for spacing of piles tested. The influence of soil movement on the lateral response of pile is also analyzed through 3-dimensional finite element analysis. The numerical results thus obtained are validated with the results of experiments. The Mohr-Coulomb material model adopted to represent the soil behaviour predicts the response of pile reasonably and compares well with the experimentally observed response.INTRODUCTIONPile foundations are adopted to support structures such as foundations of high rise buildings, transmission towers, offshore platforms, bridge abutments etc., when good bearing stratum is not present at shallow depth to bear the loads of these structures. In the recent past particularly in the urbanized areas structures are built close to one another and nearby excavation will cause a reduction of lateral earth pressure and soil movement behind the retaining wall (Ong, 2004). The reduction in support stress will induce additional movement to the pile and leading to distress in pile foundations located adjacent to supported excavation. In these situations understanding the response of piles next to supported excavations becomes essential.The behavior of piles subjected to soil movement was studied by Poulos and Chen (1996 and1997) through tests on 1g models and the findings concluded that the maximum bending moment was found to decrease with decreasing pile diameter and decreasing pile spacing . Leung et al. (2000 and 2003) studied the effects of excavation induced soil movement on pile foundations in sand through centrifuge tests and established that the restraints on the pile head would cause additional shear force and/or bending moment at the pile head, although the restraints help to reduce the pile head deflection/rotation. In the theoretical studies of Poulos & Chen (1997), boundary element method (PALLAS) was used for analysing the pile subjected to lateral soil movement and charts were proposed for designing the piles. Pan et al. (2002) and Miao et al. (2006) analysed the passive pile behavior through three dimensional finite element analyses. However research works reported on piles subjected to lateral soil movement are limited."

Jan 1, 2015

By P. J. Nicholson

The methods of reinforcement to be discussed in this paper are all insitu methods, ones that can be used on the soil structure as it exists in the ground, and do not rely on excavation and replacement of the soil. Current practice in the United States, as well as new ideas and methods, will be discussed as they relate to slope stability, retaining walls, and to other uses such as control of mine or cavity related subsidence and to liquefaction control under existing structures. The method is based on the concept of "nailing" or reinforcing the soil in place, and thereby causing a mass of soil to act as a coherent unit. When performed properly, a true gravity structure can be constructed, one that will remain intact under both horizontal and vertical loadings and that will also resist vibrational and seismic loadings.

Jan 1, 2010

By Eric Brandner

Expansive soil formations can be found throughout the United States. When subjected to wetting, many of these formations have the potential to swell and exert large uplift forces which can significantly damage lightly-loaded structures. Designing an economical foundation that can resist uplift forces is critical to prevent damage to these structures. The current solutions to control uplift due to swelling soils, such as over-excavation and replacement of the expansive material, or drilled shafts, can be costly and problematic. Piles made from recycled polymer materials may provide a solution. Due to a lower coefficient of friction along the interface than piles made from traditional materials, solid recycled plastic piles can allow expansive soils to move nearly independently from the pile when wetted. This results in a much smaller magnitude of uplift force being transferred to the structure which minimizes the risk of significant structural damage. This paper presents the preliminary results of research conducted on the use of recycled plastic piles in an expansive shale environment. The preliminary phase of the project involved the installation of six 13 in. (330 mm) diameter recycled plastic piles at a test site on the South Dakota School of Mines and Technology campus. The piles varied in length from 15 ft. to 25 ft. (4.6m to 7.6 m). Two of the piles were subjected to a full-scale compression load test in order to determine ultimate capacity, while the additional four piles are being subjected to long-term monitoring of uplift movement. A cast-in-place concrete pile, with a diameter of 6 in. (152 mm) and length of 15 ft. (4.6 m), was also installed at the test site for monitoring. The preliminary results indicate that the use of solid recycled plastic piles is a viable alternative for support of lightly-loaded structures in expansive soil environments.

Jan 1, 2009

By Stuart Coutts

"This paper presents an overview of the author’s experience related to the assessment of the base capacity of straight shafted and enlarged-base bored piles in sand. A design approach based on CPT qc is described which has been calibrated using a database of load tests. The importance of correct installation techniques with instrumentation are illustrated and a discussion is presented on the current use of high strain dynamic testing to validate compliance with design. An example of a recent project with high quality instrumented load test data illustrates the close match to the proposed best practice approach and also highlights the importance for consideration of the effects of stress relief for deep foundations installed in deep excavations.1 INTRODUCTIONContinuous Flight Auger (CFA) piles are the bored foundation pile of choice for sand deposits across Australia. The evolution of the determination of the base resistance of CFA piles has been shaped by available investigative techniques, calculation methods, and calibration of designs with laboratory and field testing. The Cone Penetration Test (CPT) has been widely used in Western Australia (WA) where the test has been commercially available via multiple contractors for more than 25 years. On the East coast, the adoption of CPT testing has been slower with a transition from traditional Standard Penetration Testing (SPT) still occurring. Dynamic pile load tests are often used to derive parameters. The influence of pile installation on performance is commonly misunderstood and is an important element on any discussion of pile capacity for CFA pile types. The interface between the base of the constructed pile and the in-situ soil has an influence on capacity such that a poorly constructed pile base will have limited (if any) contribution to pile performance within the normal working range, generally within a 10 mm movement. The research presented in this paper pertains to CFA piles (no drilling fluids) and enlarged base piles constructed using CFA techniques under drilling fluids such that clean pile/base interface is targeted. Developments in modern piling equipment and instrumentation allow the pressure and volume of delivered concrete/grout to piles to be accurately monitored at various stages of installation such that repeatable ‘best practice’ can be achieved. The changes in soil conditions that occur due to the disturbance of the install technique are also important.Although the results of this research are likely applicable to bored piles, the interface between the pile and in-situ soil (shaft and base) need to be considered for various installation techniques. The effects of stress relaxation (due to removal of soil above pile base and adjacent shaft), time to concreting, and the zone of disturbed soil around the pile shaft are paramount.2 INSTALLATION CONSIDERATIONS The pile mix (concrete/grout) and interface with the in-situ soil are also an important consideration. For example, coarse grained, poorly graded, dry, clean sand will be partially permeated by most pile mixes; such that the influenced soil will be enhanced and in instances the overall effective pile dimensions increased. Permeation of the disturbed zone of a pile or anchor shaft along with scale effects (Lehane 2009) can have significant effect on shaft capacity and shaft frictions significantly exceeding expected are not uncommon based on ‘theoretical’ dimensions. Advancements in mix technology and mix techniques also have a large influence on the pile/soil interface. The ability of the piling rig and augers to excavate a plumb and gauge hole can also have a large influence on the zone of soil disturbed adjacent the constructed pile with a resulting influence on capacity."

Jan 1, 1900

By Clifford Taylor, Alexander Zöhrer

"The execution of deep basement excavations under narrow conditions is one of the most challenging tasks in geotechnics. The vicinity of neighbouring buildings, roads, and underground structures such as sewers or power lines, quite often prohibits the application of standard solutions. In addition, legal considerations in the use of adjacent properties is becoming increasingly difficult. This paper will present some innovative approaches to overcome the above-mentioned challenges based on several case studies from central Europe. For every project the design approach as well as the techniques used for execution will be explained, detailing both the advantages and the limitations of the applications. One case study shows a deep basement excavation (approx. 17m) in the centre of Prague, Czech Republic. This project featured many challenging boundary conditions (narrow construction area, high ground water table, jet grouting column embedment into bedrock, constraints regarding use of ground anchors due to property rights, etc). The realisation of the complex design is described and illustrated in detail. Other case studies will show the combined application of bored piles with jet grouting and also explain the design of vertical prestressed anchors for retaining walls.INTRODUCTIONThe development of urban areas has always presented challenges, from access for equipment and materials to the rectification of existing foundations in unknown condition. Compounding these is the increasingly stringent requirements to retain, maintain and reduce impact on culturally and historically significant structures. As available space is becoming more limited, optimisation of real estate has resulted in buildings getting higher and their basements deeper below ground. Two or more basement levels are quite common, with typical excavation depths ranging from 5 to more than 10m. Additionally, we are faced with neighbouring buildings that are equally high, deep and massive. These buildings directly adjacent the retaining structure require underpinning to limit settlement, and in cases where they are within just a few meters, this building mass generates additional earth pressure for the retaining wall to support, resulting in complex loading cases.This paper highlights several common challenges and explores the measures implemented to overcome them. The challenges and examples of either design based solutions or practical applications will focus on the following topics – the limitations of conventional geotechnical construction methods, overcoming challenging geology and the requirement for watertight basement constructions."

Jan 1, 1900

By Remco Offenberg, Marcel Bielefeld, Martijn van Delft

The question of the continued suitability of existing foundations arises when the function of the superstructure changes. This can occur when the superstructure is replaced or when the existing structure is expanded, leading to higher loads on the existing foundation. Quite often it is a challenge to define the suitability (with respect to integrity, bearing capacity or both). The lack of information on the existing foundation (such as pile dimensions, installation records, original soil investigation, design calculations, etc.) makes it frequently seemingly impossible to assess whether the foundation or foundation elements can be re-used. The paper outlines the tools available to an engineer to evaluate existing foundation piles for potential re-use. The paper illustrates the application of these tools through a few case studies from The Netherlands, including the evaluation of a 400 years old bridge foundation to address increasing traffic loads.

May 1, 2022

By N. Schmitz

This paper explains how new digital solutions improve reverse circulation drilling operations. Upgrading field-proven reverse circulation drilling (RCD) rigs with new digital technologies enables semiautomated drilling, with upgrade options for fully automated & remote drilling. Key elements of the improvements are electrically controlled valve systems, process instrumentations, a state of the art machine controller and drilling operation via a touch control panel. Automation of core processes, such as adding drill pipes, reduces set-up times, increases machine uptime for drilling and as a result efficiency. While drilling, sensors provide continuous feedback, which is used to automatically adjust e.g. the weight on bit to the optimum; resulting in an increased rate of penetration and less wear and tear. While in the past hydraulic power packs (HPU) have typically been operated at a constant high-performance level with related high fuel consumption, a new interface between the machine controller and the power unit regulates the HPU performance exactly according to the actual drilling operation needs. This leads to significant fuel consumption reduction. The safety benefits of the digital improvements are the ability to remotely operate the rig in challenging site conditions via a mobile operator panel.

Sep 8, 2021

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan PhD

The experience gained during more than 900 Crosshole Sonic Logging (CSL) tests on drilled shafts shows the importance of establishing proper project acceptance and repair protocols. Drilled shaft evaluation is a multidisciplinary task that should not be left solely to the outcome of the CSL test. This test allows to characterize and delimit areas of different qualities of concrete, and it is important that all the interested parties understand the difference between flaws and defects. The information presented here is intended to give a guideline to contractors, inspectors, engineers, owners and clients on how to deal with acceptance and remediation of defective drilled shafts, detected using CSL tests. A database of flaws is presented depending on their location, intensity and remediation method. Procedures that allow the flaws to be analyzed are presented in order to dismiss or classify them as defects. In many cases, the CSL test may indicate an anomaly, but by coring the concrete and analyzing the structural demands and conditions, the flaw can be classified as non-severe. When flaws are classified as defects, their repair will depend on the area where they are located in the drilled shaft pile. In this document two procedures are described for repairing defects depending on their location. For defects in the drilled shaft head area, the procedure takes into account the interaction between the new and old concrete. For repairing the middle zone of the drilled shaft by grouting, the major concerns are the difficulty of accessing through the drilled shaft at deep depths and the communication between boreholes. For defects at the drilled shaft tip, two proposed remediation methods are presented. Finally, tomography tests are presented to compare the effectiveness of remediation by grouting.

Oct 1, 2022

"What can we do in ground engineering to reduce damage to the environment, to repair historic pollution, to reduce our demand on basic resources and to reduce the carbon footprint of our industry? Some developments in geotechnical engineering are already heading in the right direction. These include reductions of ground pollution from grouting, improved dewatering procedures and advances in mix-in-place processes, ground improvement and jet grouting.There is increased interest in certain promising technologies (for example, drilled partial or full displacement piles), but this approach remains for the moment somewhat avant-garde. These piles require substantially greater power to install, and the overall sustainability balance for general application has yet to be shown to be in their favour. They are particularly suited to polluted sites where the problem of dealing with spoil would be costly and where, in the past, driven cast in-situ piles would have been employed. Drilled displacement piles offer some environmental benefit over driven piles in that they cause far less drawdown of potentially contaminated near-surface ground into sensitive, underlying aquifers.There is also great interest in various means of increasing the frictional capacity of bored piles, both conventional auger and continuous flight auger (CFA) piles, by threading or ribbing the soil/pile interface. The increase in adhesion capacity allows reduction in the pile dimensions necessary for a specific load. This obviously leads to less construction waste, but also to less permanent material consumption in the piles and also in the pile caps.The role of ground improvement remains significant for brown land sites and lower capacity foundations. Information technology (IT) has improved the quality assurance of stone column construction, for example. From the sustainability point of view, this is a good news method; here is no cement, no pollution and little obstruction to future redevelopment. We now need to introduce recycled crushed materials instead of natural aggregate as general practice and the technique’s green credentials will be really compelling."

Jan 1, 2009

By Emad Farouz, Francis A. Abreu

"This paper presents a case history of a successful construction-phase pile load test program that optimized the pile design in challenging ground conditions at the Great Neck Wastewater Treatment Plant in the Town of North Hempstead in Nassau County, New York. The improvements and expansion of the wastewater treatment plant included the construction of several new structures to comply with new stringent nitrogen discharge requirements and new design flow. The challenging ground conditions included up to 20-ft thick organic deposits with weight of hammer blow counts and up to 14 percent organic content and tidal ground water that was near the ground surface. The foundation design evaluated various deep foundation alternatives and selected driven closed-ended pipe piles then filled with concrete as the most suitable foundation. The selection process included considerations of cost, risk, vibrations, noise, and schedule. The contract documents utilized an innovative approach of performing an optimization load test program that was implemented during construction to optimize pile lengths and reduce potential vibration and construction schedule.This paper discusses the details of the successful load test program including static testing, dynamic testing, and the innovative contracting approach utilized to implement the construction phase load test program. It also discusses the successful development and implementation of driving criteria for production piles and construction challenges. The successful load test program resulted in savings of several hundred thousand dollars, optimized schedule, and lower environmental impacts.SITE AND PROJECT DESCRIPTIONThe Great Neck Water Pollution Control District (GNWPCD), located in the Town of North Hempstead in Nassau, New York, owns and operates a municipal wastewater treatment plant (WWTP) that discharges treated effluent through an outfall to Manhasset Bay, which is a tributary of the Long Island Sound. The site is located west of Manhasset Bay and is surrounded on three sides by local roads, and commercial, industrial, and recreational properties. The site has a gentle slope ranging from elevation +20 to +7 from west to east, respectively, based on the Nassau County Datum.To comply with new nitrogen discharge requirements and new design flows, the GNWPCD contracted CH2M HILL, Inc. and William F. Cosulich Associates as a Joint- Venture (JV) to design and provide services during construction of eight new advanced nitrogen removal facilities."

Jan 1, 2017

By Hitendrabhai S. Dewangan, Dr. Aashish A. Mehta

Pile foundation is widely used in construction of marine structures. In offshore & marine piling work, drilling/boring supporting fluid is used to stabilize the borehole (excavation) prior to tremie concrete. The poly-fluid is a synthetic drilling granular polymer characterized by high molecular weight.it is mainly used for the preparation of stabilizing and lubrication mud in drilling of deep foundations. Disposal of polymers after using it into the sea, pollutant the sea environment, which may be harmful for living organisms inside sea. To reduce the pollution in offshore/Onshore, it is essential to take the precautions during flushing operation with proper recycled, reused & it’s Disposal. To provide economic and environmental solutions, used slurry was treated with addition dose of fresh material/polymers. The amount of fresh materials/ Polymer to be added can be decided based on (viscosity, density and pH value) test results. Finally, initiate water flow and air agitation as required. Run the tests on the re generated slurry before transferring to storage tank. Also, after storage, polymers will be reused for next operation. Moreover, mud wastage coming from borehole will also be disposed at suitable dumping places.

Sep 1, 2022

By Michael J. Marasa

"Geotechnical engineering and construction primarily relies on the subsurface characteristics of the particular site; however, obtaining both accurate and precise information on those features is challenging due to the numerous factors involved in testing procedures used to analyze varying site geology. This includes a detailed and thorough geotechnical investigation to understand the site conditions, allowing the implementation of the most practical and economical solution.This paper presents a case history of the installation of wick drains and construction of aggregate piers on the site of a large facility to be constructed in Memphis, Tennessee. Throughout intensive subsurface investigations, highly variable soils were encountered, requiring settlement control and increased bearing capacity. This paper will discuss the design and installation of the systems constructed, and procedures and execution of the work to ensure design specifications were achieved.BackgroundA 1.4 million square foot expansion directly adjacent to an existing 1.1 million square foot distribution facility in Memphis, Tennessee was planned to serve as a centralized facility for increased production. The first phase of construction included an 858,000 square foot warehouse and parking lot for approximately 400 trucks to the north of the existing structure. The anticipated column load for the warehouse was 125 kips; slab design bearing pressures ranged from 200 to 500 pounds per square foot (psf) and elevations ranged from EL. 264 to 282. Parking lot elevations ranged from EL. 264 to 290, requiring a design life of 10 years with an estimated 100 in- and out-bound trucks daily and maximum weight of 80 kips per truck. The second phase of construction took place east of the existing structure, and included a 794,000 square foot multi-level warehouse, a 100,000 square foot office, and additional employee parking. The anticipated column load for the second warehouse was 225 kips and slab design bearing pressures ranged from 200 to 500 psf. Elevations ranged from EL. 267 to 282. Anticipated column loads from the office were 25 125 kips, with slab design bearing pressures ranging from 100 to 200 psf. Due to the varying elevations within each planned footprint, up to 18 feet of new fill was required to match the existing structure’s finished floor elevation (FFE) at EL. 282."

Jan 1, 2017

By Stefan Swartling, Rudy Lyon, Donald A. Bruce

"Since their first production application in Sweden in 1995, water-powered, down-thehole hammers (WDTH) have been used throughout the world in many different drilling applications, total lines, over 25 million lineal meters of drill hole. This paper reviews the history and principles of down-the-hole drilling (DTH) in general with both air and water, before focusing on the details of WDTH hammers. A summary of the numerous and considerable advantages of WDTH drilling is provided, with particular emphasis on their superior productivity, smaller deviation, applicability in sensitive/urban conditions, environmental protection and much reduced energy requirements.HISTORICAL PERSPECTIVE ON PRODUCTION DRILLING METHODSAir-flushed drilling with top hammers began in the mining industry in Sweden in 1873, while down-the-hole (DTH) drills, again with air flush (and activation) became operational in 1950. During that same time interval, Simon Ingersoll had patented the first steam-powered, top hammer rock drill to provide higher productivity in blast hole drilling. It is well known that water, as an activating, flushing and cooling medium, has many significant advantages over the use of air. However, it was not until 1973 that top hammer systems (either air or hydraulically activated) for larger rigs were adapted to the use of water flush, typically via “under the head” swivels.The concept of a water-powered, down-the-hammer (WDTH) had been explored prior to G. Drill acquiring the original patent from Atlas Copco in 1988. LKAB, a huge underground mining company owned by the Swedish Government and providing about 90% of the European Union’s iron ore, purchased G. Drill in 1991 and encouraged the commercial development of the WDTH. The first full-scale WDTH production works were carried out for LKAB in 1995, since when over 25 million lineal meters of drilling have been recorded in both underground and surface applications.In 2001, G-Drill was renamed Wassara, which today still holds the worldwide patents for WDTH technology. Regarding North American usage, the first significant application was by Advanced Construction Techniques (ACT) Ltd. during the test grouting program conducted for the U.S. Army Corps of Engineers at McCook Reservoir, Chicago, in 2002. Since then, WDTH has become the tool of choice for specialty drilling and grouting contractors on dams and other major structures throughout the U.S."

Jan 1, 2015

By Rob Jameson

"Although seismic retrofit is recognized as a key micropile application, widely-used reference documents do not clearly address design and testing recommendations for micropiles that are loaded primarily under seismic conditions. The principles of micropile design and construction and their application to seismic retrofit projects are well understood and executed by leaders in the field. As the micropiling market grows, a wider audience relies on the information presented by DFI and similar industry groups. State-of-practice updates appear periodically in conference proceedings, but examination of recent bid documents makes it clear that there are opportunities to improve the specification of load, deflection, testing and acceptance criteria on many seismic retrofit projects. Updates to the FHWA Manual or DFI Sample Specification that specifically address seismic retrofit cases would be useful tools to disseminate information and enhance the state of practice.Micropile Survey UnderwayAs one step in this process, I am distributing surveys to contractors and designers prior to DFI Super Pile ’09 (June 4-6, San Francisco) seeking recommendations for design and testing procedures applicable to seismically loaded micropiles. I am also requesting any existing references that could be promoted as a standard for these cases. Anyone interested in participating in this survey, should contact me at rjameson@malcolmdrilling.com. Seismic RetrofittingMicropiles are ideally suited to seismic retrofit applications. Their high-tensile and compressive capacity can sustain the large concentrated loads induced during seismic events. They can be installed within and around the access limitations of existing structures, and can be drilled through and grouted into the wide variety of soil and rock materials encountered in seismically active zones.Seismic retrofits have included micropiles since the early 1990s, and they are now widely specified in the Western U.S. In the San Francisco Bay Area alone, thousands of micropiles have been installed for seismic upgrades of highway and transit aerial structures, and retrofits of commercial, residential and public buildings. Micropile use is growing in both public and private sectors, with large-scale retrofit projects currently underway for both the Bay Area Rapid Transit (BART) system-wide upgrades and renovations at San Francisco Airport."

Jan 1, 2009

By Dan Brown

Deep foundation contracting for transportation projects in the United States has typically followed the design-bid-build model in which contractors bid on a specific work product according to relatively inflexible prescriptive specifications. With continuous flight auger piling and the many types of proprietary drilled displacement auger piling, there appear to be advantages to contracting this work according to a different model. This paper provides a discussion of the use of a performance specification for this work in which the contractor has greater freedom to choose the most appropriate foundation system and also greater responsibility for the performance of the completed foundation. With public agencies subject to open bidding, this type of contractual arrangement presents opportunities to encourage innovation. There are also challenges for implementation in public works projects, notably the selection of qualified contractors and the verification of performance requirements on production foundations.

Jan 1, 2006

By Julie H. N. Hampden, Per G. Reinhall

"Executive summary: Impact pile driving of steel piles is a common construction practice in freshwater and marine environments for the building of structures and foundations. This practice produces extremely high sound levels underwater that have proven injurious to aquatic fish and wildlife. To limit impacts to sensitive species, resource management agencies employ a variety of different strategies including timing restrictions to limit in-water construction windows to those months when there are low flow conditions in lakes or rivers, to those hours when tides are low, or to periods of the year when species of concern are least likely to be present in the project vicinity. In addition, permitting agencies have identified noise thresholds above which sensitive species could be injured, resulting in additional project conditions to curtail the extent of project noise impacts including: limiting the number of piles or pile strikes per day, requiring biological monitoring, and mandating the use of noise attenuation techniques, such as bubble curtains and cofferdams. Numerous studies have shown current noise attenuation techniques are costly and provide limited or variable noise reduction [1-3]. This is because the noise from pile driving is not only transmitted through the water column, it is also transmitted through the sediment back into the water column [1, 4-8]. Though these protective measures may help to reduce project impacts, they also result in additional complexity, expense, and potential risk for project delivery. Marine Construction Technologies, a Public Benefit Corporation, in collaboration with University of Washington and Washington State Department of Transportation, has developed a pile that can be installed with standard pile driving technologies (vibratory or impact hammers) and consistently decreases the total noise transmitted into the water. The double-walled pile is relatively quiet in comparison to unattenuated piles or existing noise attenuation techniques. This technology not only reduces the risk to sensitive species by minimizing the extent of potential impacts, it also reduces potential risks to project delivery by limiting the size of monitoring areas, minimizing the need to cap daily production rates, and eliminating the need for deployment of additional noise attenuation devices. Results from finite element modeling of the pile, scaled prototype testing, and full scale field testing in Commencement Bay (October 2014) and Vashon Island (October 2015) in Puget Sound, Washington indicate a reduction the peak sound pressure between 14 and 20 dB relative to single walled piles at a range of approximately 10 meters. These tests also confirm that the double-walled piles provide drivability similar to standard steel piles. In addition, preliminary calculations for capacity and structural characteristics demonstrate that double-walled piles provide equivalent or better performance than same-sized standard piles."

Jan 1, 2017

By Rangaswamy. K, Naga Sivaji

A stone column is one of the most commonly employed methods of ground improvement techniques. This method used to increase the strength, decrease the compressibility of loose granular and finegrained soils. Also, it accelerates the consolidation in clays and reduces the liquefaction potential of sands and silt soils. In general, the stone column contains 15 to 75mm stone aggregates. In reality, it is not easy to avail the natural stone aggregates due to unavailability in locally nearby places. Present work aims to replace the stones partially or entirely by scrap tyre chips as an alternative material. The utilisation of recycled tyre chips in ground improvement is an environmentally friendly solution and avoid the disposal of tyre chip waste in large pits. Model tests conducted on marine clay with encased end bearing stone columns (ESC) constructed with a mixture of stone aggregate and tyre chips with sizes 4.75 to 10mm. The column diameter is 75 mm, L/d ratio maintained to 5.3. Non-woven geotextile wrapped encased stone column has introduced in the soft marine clay model. Encasement prevents the lateral squeezing of aggregates into the surrounding clay and protects the drainage function of the stone column. A set of load-settlement tests were conducted on both the clay model and clay model treated with the stones-tyre chips column. The model was loaded by the tri-axial loading frame. Shear strength parameters of stones and tyre chips were determined by large size direct shear tests. Model test results are concluding that the load-carrying capacity of the clay is improved significantly after installing the stone column in it. The encasement increases the load-carrying capacity and stiffness of the ordinary stone column. It is also proved that the stone aggregate could be replaced partially by tyre chips up to 60% without a significant reduction in its performance.

Nov 1, 2022

By Venkatesh S. V J, Shubha M, Srilakshmi G

Choosing for the best option of pile foundations to overcome large lateral and uplift loads for the foundations in transmission line towers/offshore environment is still being a concern to achieve the required capacities but also by considering the suitability aspect in the environment. The objective of this paper is to review the methods that have been done for knowing the uplift resistance and lateral resistance of pedestal piles. Investigations by different methods such as experimental studies, numerical and analytical studies have been done by various researchers in order to evaluate the response of a belled pile. These methods are discussed in this paper and the comparison with straight shaft pile based upon the test and analysis. The results indicated that the uplift resistance and lateral resistance were significantly increased with the adoption of belled piles than straight shaft piles.

Sep 1, 2022

By James W. Niehoff

"Prior to 2003, most high rise structures in Honolulu, Hawaii were supported on driven pile foundations, extending through shallow coral strata and bearing in competent formations at depths of 100 ft (30 m) or greater. In 2003, the 40-story Hokua Tower became the first building in Hawaii to use continuous flight auger (CFA) piles for support. These piles derived most of their capacity from side shear in the shallow coral formations, which reduced their required lengths to less than 100 ft (30 m) sand significantly increased their capacity. Not only did CFA piles prove to be more efficient and cost-effective than driven piles, but the reduced noise and vibration associated with their installation made them and drilled piers the foundations of choice for most mid- to high-rise projects going forward. Because drilled foundations were new to Hawaii, it was necessary to develop effective design parameters for the unique soil and rock conditions found within this urban area. While drilled foundations were found to have many advantages over driven piles, construction techniques had to be modified to compensate for extensive voids in the coral formations. This paper presents a compendium of the data derived from numerous full scale, instrumented load tests conducted during the past decade and provides guidance for the design and installation of CFA and drilled pier foundation systems in areas having geologic settings and history similar to that of Honolulu.INTRODUCTIONThe State of Hawaii is one of the most remote areas in the world, lying nearly 2400 miles (3800 km) from the nearest continental land mass. In spite of this vast distance, the population of the islands has grown to over 1 million people, the majority of whom live within and in close proximity to the City of Honolulu on the Island of Oahu. The city is densely populated with over 400 high rise apartments, condominiums, hotels and office buildings located within 5 miles (8 km) of the city center (Fig.1). Nearly all of these buildings have been constructed within the past 50 years."

Jan 1, 2016

By Tsuyoshi Honda, Kazuhiro Kaneda, Masayuki Imai, Kazuo Konishi, Kunio Higashinaka

"In recent years, the demand for measures to control liquefaction of existing airport runways and harbor structures has increased. However, from the perspectives of constructability and cost, application of grid-form deep mixing walls to these types of structures requires the formation of wider grid spacing as compared with conventional designs. In this research, we focused on the extent of liquefaction and ground surface settling when grid spacing is made wider than conventional designs. We conducted centrifuge model tests, and confirmed the liquefaction suppression effect when grid-form modifications involving wide grid spacing are adopted under asphalt pavement. The tests were conducted under conditions that included changing the grid spacing and groundwater level. When the groundwater level was high, an increase in water pressure was observed, even within the grid. However, when the groundwater level was low, the increase in water pressure inside the grid was suppressed. We also found that if the generation of water pressure can be suppressed, the amount of settling due to liquefaction can also be controlled.INTRODUCTIONOne construction technique used as a countermeasure to liquefaction is grid-form deep mixing walls. Grid-form deep mixing walls are a construction technique for which improved grid-shaped wall bodies are built into the ground below the surface using a deep mixing method. This construction technique minimizes shear deformation by surrounding liquefied ground with improved wall bodies, thereby preventing liquefaction (Fig.1). With conventional designs, grid-form deep mixing walls determine the grid spacing that can deter liquefaction based on a ratio of the grid spacing L to the improved depth H (ratio = L/H). Ordinarily, designs are implemented with an L/H ratio of 0.8 or less (PWRI, 1999).In recent years, a demand for measures to control liquefaction of existing airport pavement and harbor structures has increased. However, when liquefaction countermeasures are implemented at these types of facilities and structures, the construction work must be implemented while the facilities and structures remain in service. Therefore, temporal and spatial constraints must be considered. In addition, unlike conventional liquefaction countermeasures, performance requirements are such that, even if some degree of liquefaction is allowed, the performance is acceptable as long as the amount of settlement is within a predetermined value. Therefore, if grid-form deep mixing walls are applied to these structures, grid spacing that is wider than conventional standards is desired."

Jan 1, 2015