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By Mark Johnson, Mathew Janes

"The Resonator RD 260 Resonant Pile Driver delivers ground disturbance free, high production pile driving. The Resonator has recently been used on numerous production pile driving sites in the Netherlands and Melbourne, Australia to drive piles in sensitive areas where conventional pile drivers could not be used. Two case histories are provide in this paper which demonstrate the features and benefits of Resonant pile installation.. In the Netherlands the Resonator RD 260 was used at the Vopak Oil Storage facility in the Port of Rotterdam to install pipe and sheet pile within an active pumping gallery. The site demanded vibration free pile installation to construct a cofferdam within sensitive, highly valued assets. Access was an issue and schedule demands were stringent as shutdown windows were narrow. The RD 260 provided ground disturbance free piling immediately adjacent to fragile structures. At Vopak the only site access was using a large crane positioned over 40 m from the location of pile driving. Driving was conducted amongst 900 mm dia pipes carrying heated crude oil.In Melbourne the RD 260 was used to drive GU 18 sheet piling adjacent to light rail easements. The project was the first of many grade separations being constructed within Melbourne urban areas to lower the light rail and provide quieter rapid transit. The original trial used an RGT MR105 series vibrator but noise and vibration criteria were exceeded. The RD 260 was brought in for a trial and performed with high production and produced negligible ground vibration. Up to 17 sheet piles 14 m in length were driven in a 2.5 hour window during the trial.IntroductionThe Resonant Pile Driving method is gaining acceptance around the world as a new method to rapidly drive piles free of ground borne vibrations. The high frequency vibrator resonates the pile, essentially turning the pile into a spring, to excite the toe of the pile with high accelerations and low amplitude. High acceleration with low amplitude generates high penetration rates but the high frequency stress waves are quickly dissipated in the soil. Typically ground borne vibrations are measured at below 1 mm/sec within 1 to 5 m of the pile. The Resonant method can drive a pile next to a glass of wine, without spilling, as has been demonstrated on numerous piling sites.How Does Resonance Work?The Resonant method uses a hydraulic piston - cylinder geometry to generate high magnitude, high frequency oscillating force. This is a very different mechanism than the eccentric mass technology used in conventional and variable moment vibrators.A unique valve geometry achieves the high frequency flow switching necessary to oscillate the hydraulic piston at up to 180 Hz (10800 VPM). The valve is controlled electronically for maximum accuracy of the desired frequency. The volume of hydraulic oil delivered through the valve to the piston (flow rate) determines the amplitude while the hydraulic pressure determines the peak force."

Jan 1, 1900

By Stephan A. Jefferis, Adrian H. Bath

"This paper draws together some themes on the durability of barrier systems, and particularly cementitious systems. For contaminated land and water retaining structures, durability can be poorly addressed at all stages of a project, from specification, to barrier material selection, barrier design including toe-in and through to performance assessment in operation. Permeability (hydraulic conductivity) is a dynamic property which will vary over time as reaction processes propagate through a barrier. However, laboratory testing, when undertaken, tends to be focused on short term tests with aggressive chemicals so that the effects of longer-term processes such as carbonation and leaching by permeating water are missed. For water retaining structures, carbonation and leaching actually may be the most significant processes affecting barrier performance as the groundwater adjacent to many water bodies can be otherwise rather benign (as regards bentonite and cementitious systems). These and other reaction processes have been modelled in the arena of nuclear waste repositories and procedures are well recognised. However, such procedures have yet to be widely adopted for the assessment of other barrier systems.INTRODUCTIONOver the last few decades there has been an enormous amount of laboratory research on the durability of barrier materials or more specifically papers reporting the results of permeability tests. Unfortunately there is a much smaller literature on scaling test results to barrier dimensions in the field or to required design lives. Although in the geotechnical industry durability research has been largely laboratory based, in the nuclear industry where relevant timescales are multi-millennia rather than decades, research has been heavily underpinned by geochemical modelling. A significant purpose of this paper is to examine the tools that may be used to analyse the results of tests on barrier materials used in geotechnical engineering, for example, for water retaining structures and contaminated land and draw the attention of the construction industry to the potential of the modelling procedures developed for nuclear repository assessments. Modelling can help to identify underlying processes and so augment information from laboratory testing focused on changes of physical properties such as permeability and strength."

Jan 1, 2016

By Osamu Taki

The development of new auger bits for soil cement column drilling equipment has made it possible to create a homogeneous mixture of soil and cement-reagent slurry. As a result, soil-cement columns are used for foundations of houses and buildings, with reliable results, as demonstrated by many field projects and laboratory tests. This paper presents and discusses construction techniques for soil-cement columns, characteristics of the soil-cement solid, quality control, bearing test results, and soil-cement foundation design procedures.

Jan 1, 1992

By Akhila Manne, Prasad P. V S R

Storage tanks are heavily loaded thin-shelled structures that exert large loads on and require large foundations to support them. They are generally very sensitive to foundation settlements as it may hinder the performance of tanks resulting in significant commercial or social impacts. Selection of their foundation is dependent on availability of suitable ground and limitations imposed by design specifications. Design of the tank foundations is generally based on theoretical methods and validation by representative field tests. This paper reviews settlement criteria for storage tanks as per national and international standards, case studies of large to medium diameter tanks supported on deep foundation i.e., bored cast-in-situ piles and shallow foundations on improved ground and their performance during load tests & hydro-tests is discussed. Paper concludes that storage tanks can also be supported on shallow foundations resting on improved ground reducing the settlement, time and cost significantly depending on the sub-soil.

Nov 1, 2022

By Dan Mahrt

"In June of 2009, a slope failure occurred along River Road in Bismarck, North Dakota. The slope failure affected approximately 300 feet of River Road with vertical displacements up to 3 feet, resulting in closure of the road. River Road travels along the Missouri River in Bismarck in a geologic area riddled with historic slope failures of varying sizes. River Road is a city roadway which travels along the Missouri River. The toe of the failure extended into the Missouri River, therefore methods to repair the slope needed to be constructed within United States Army Corps of Engineers (USACE) requirements, and be acceptable to the City of Bismarck. As this is a scenic area along the river, the stakeholders desired to maintain the scenic landscape along the roadway as a part of the slope stabilization.Due to the magnitude movement of the failure mass, the geometry of the failure was relatively easy to evaluate. In evaluating remediation options and collaborating with the USACE, the team determined that the scarp was situated primarily within the navigable portion of the Missouri River. This required USACE approval for any repair or remedial work downslope of the roadway. The City of Bismarck wished to reopen the roadway as soon as possible, therefore stabilization options were limited to working within the road right-of-way to avoid permitting for working within the navigable waterway.The remediation solution for this project involved a combination of driven H-pile and placement of lightweight fill to re-construct the roadway at the original grades, and avoid impacting the navigable portions of the Missouri River. This paper discusses the unique project constraints and the innovative solution using multiple technologies to successfully stabilize the slope.BackgroundIn June 2009, Bismarck, North Dakota experienced two consecutive days of significant rain resulting in over 5 inches of precipitation in a 36-hour period. Shortly after these rain events, a slope failure was noted on River Road, a city street along the Missouri River in Bismarck. Initial findings noted the slope failure affected about a 300-foot long portion of the roadway, with vertical displacements of about 2 feet. The city of Bismarck closed the roadway and began evaluating repair solutions for the road."

Jan 1, 2016

By Ramanathan Ayothiraman, Anurag Singh

"An experimental program was undertaken to investigate the effects of randomly distributed basalt fibre on the index and engineering properties of Dhanori clay and to compare its performance with the properties of soil reinforced with polypropylene fibre. In the present investigation, 7 groups of soil samples were prepared at four different percentages of basalt fibre and polypropylene fibre content and tests were done for measuring their consistency limits, compaction characteristics, unconfined compression strength and consolidation properties. The test results indicate that the inclusion of basalt fibre in Dhanori clay resulted in significant improvement in properties. The improved properties are not comparable with polypropylene fibres, nevertheless, the improvement by basalt fibres is able to meet the typical design target values and the cost is very much less than synthetic fibres. More importantly, basalt fibres are environment friendly.INTRODUCTIONConstruction of buildings in low lands with engineered filling, flexible and rigid pavements for highways/airfields, and embankments for highways/railways are also part of major infrastructural development in addition to construction of tall buildings, bridges/fly overs, major dams and underground structures. The later projects require different improvement techniques than that is adopted in the former projects. Ground improvement techniques such as use of reinforcement inclusions within soil found as an effective and reliable technique. Especially such modification by fibre reinforcement, is primarily possible in engineered filling, pavements subgrade and embankments, where surface mixing is easier; and may not be feasible when stabilization/modification is required for deeper depths. In comparison with conventional reinforcement using geosynthetics (strips, geotextile, geogrid, etc.), there are some advantages in using randomly distributed fibre as reinforcement. In past few decades, the discrete fibres are simply added and mixed randomly with soil, in much the same way as cement, lime, or other additives.There are several studies (Ziegler et al. 1998; Puppala et al. 2000; Bei-xing et al. 2004; Cai et al. 2006; Tang et al. 2007, 2012, 2016; Abdi et al. 2008; Viswanadham et al. 2009; Le et al. 2015) that investigated the behaviour of polypropylene fibre-reinforced soil and reported that an increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential. The length of fibres had an insignificant effect on soil characteristics, whereas fibre contents proved more influential and effective. A study on rubber fibre conducted by Hambirao and Rakaraddi (2014) mentions that tensile cracking of clays can be improved with the inclusion of short rubber fibres, optimum fibre content was about 15 % of weight of soil. Several experimental studies (Babu et al. 2008; Chaple and Dhatrak 2013; Vibhakar and Nahta 2014; Soundara and Senthilkumar 2015; Goyal et al. 2015; Jayasree et al. 2014, 2015) were conducted on coir fibre-reinforced soil and concluded that it helped in reducing the swell potential and 1% fibre by weight of the soil almost doubled the CBR value. Martins et al. (2015) found that 4% of sisal fibre by weight of the soil reduced the visibility of cracks. Pillai and Ayothiraman (2012), Ayothiraman et al. (2014) and Sahu et al. (2016) have demonstrated that human hair fibres can be used to improve the properties of both fine grained and coarse grained soils."

Jan 1, 1900

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 Tracy Brettmann

In recent years the Augered Cast-In-Place (ACIP) Pile industry has seen a substantial increase in the quality control options available to Contractors, Engineers, and Owners. Quality control methods range from the simple, manual techniques that have been used for years to new computerized installation monitoring equipment and nondestructive testing methods. Our ability to monitor and test ACIP piles has grown to such a degree that the industry is struggling to determine how much quality control is enough. This paper reviews the many options available and describes the pros and cons of each. The various nondestructive testing methods, in particular, have been difficult to apply reliably due to misapplications of methods and misinterpretation of the results. ACIP piles have unique properties that require the various nondestructive testing methods available be considered very carefully in determining the method most appropriate for a particular use. Some nondestructive testing methods, as well as automated monitoring equipment, potentially can be applied effectively to increase the level of quality control for ACIP piles. The experience gained on real projects using these new methods, in conjunction with the old procedures, provides valuable information for future applications.

Jan 1, 2000

By J. S. Lee, R. K. Massarsch

"A 3.2 km long immersed road tunnel forms part of the Busan-Geoje Fixed Link in South Korea, which connects Korea's second largest city Busan, with the island of Geoje. To ensure the water tightness of the joints of the segmental tunnel structure and to limit the forces in the shear keys, the differential settlements have to be limited. This was achieved by extensive soil improvement of the marine clay below the tunnel with cement deep mixing (CDM) and sand compaction piles (SCP). This paper focuses on the characteristics of the marine clay, the basic design principles, layout and constructional issues of the CDM soil improvement, and numerical and numerical analyses to predict settlement and stability.INTRODUCTIONThe Busan-Geoje Fixed Link consists of two short cut & cover tunnel access ramps, a 3.2 km long immersed tunnel (Figure 1) and two long span cable stayed bridges. The tunnel consists of eighteen concrete elements each of 180 m length having a rectangular cross section of 26.5 m in width and 10 m in height. The tunnel elements are cast in a dry dock on shore and floated out to the sea, immersed in their final positions on a gravel bed in pre-excavated trench and connected to each other by a dual gasket system. The water depth was up to 50 m making the tunnel of the deepest yet constructed. After immersion, the tunnel is protected by backfill material at the sides and rock armour on top. Each tunnel element consists of eight 22.5 m long segments. The joints between the segments and between the tunnel elements are equipped with EDPM water stops, Omega seals and concrete shear keys. The longitudinal displacement behaviour of the segmental tunnel structure in the varying ground conditions represents a complex soil-structure interaction problem which has been modelled with a FEM structural model representing the tunnel, the joints and with springs to represent the soil that are derived from the PLAXIS soil/foundation models. In order to ensure the water tightness of the joints which have limited opening capacity and to limit the forces in the shear keys, differential longitudinal settlements have to be limited. This is achieved by limiting the variations in subgrade modulus along the alignment and it in practice means that differential settlements are limited to a few tens of millimetres. Without soil improvement of the marine clay below the tunnel, long-term tunnel settlements of up to 400 mm were predicted when taking into account the likely variations in the trench profile, backfilling and uncertainties in the soil properties. Such large total settlements led to large variations in the sub-grade reaction along the alignment, which in turn resulted in significant differential settlements, unacceptable joint opening and large shear key loading. It was therefore decided to carry out extensive soil improvement with cement deep mixing (CDM) (CDIT, 1999) and sand compaction piles (SCP) (Kitazume, 2005) after studying a number of foundation alternatives."

Jan 1, 2015

By J. Racinais, P. Vincent

"In September 2011, Menard Oceania (MO) was engaged by Mac Mahon John Holland Joint Venture (MJHJV) to provide ground improvement solution for the $34bn Ichthys LNG development. With close to 400,000m2 of mangrove swampland set to be reclaimed and improved, this project was a great opportunity to showcase the technical, commercial and environmental benefits that Dynamic Replacement (DR) ground Improvement technique can provide. The ground improvement works involved complete design and construction for the Ichthys LNG site located at Blaydin Point on a low lying peninsula in Darwin Harbour. Dynamic replacement and stone columns technique were selected to treat intertidal mangrove mud to achieve required bearing strength, stability and limit settlement to an acceptable levels. The site is underlain by a 3m to 5m thick layer of highly organic mangrove muds with very soft shear strength ranging from 0kPa to 12kPa at depth. The site is exposed to daily sea water level tidal variations of up to 8m, which created significant constructability constraints and slope instability risks. This paper presents the design philosophy, the process involved in the selection of the construction methods, the site constraints encountered during the works and a review of the results achieved, quality control and post constructions performance.INTRODUCTIONInpex Browse, Ltd (Inpex) and its partner Total are developing the Ichthys gas field to pipe gas to onshore facilities at Blaydin Point on the south side of East Arm in Darwin Harbour. The proposed LNG plant consists of gas receiving facilities, 2 x 4.2Mtpa nominal capacity LNG trains, LPG and condensate production facilities, product storage and export facilities, a module offload facility (MOF), a flare pad (FP) and associated off plot facilities.The proposed on-shore facilities are located on extremely soft intertidal mangrove muds, therefore an appropriate ground improvement was required to achieve required strength and stability of site works and limit long term settlement to an acceptable level.Various ground improvement techniques were studied to select the most suitable for the ground conditions and site constraints encountered at the Blaydin point site. Dynamic replacement technique was selected for onshore section to improve soft mangrove mud to depths of 5.5m and Stone Columns (SC) technique was selected for MOF off-shore section to improve intertidal deposits to a depth of 2.5m.This paper presents DR design and construction works performed between December 2012 and August 2013 at Flare Pad Area."

Jan 1, 1900

By Tracy Brettmann, Melis Sutman, C. Guney Olgen

"The use of energy piles for geothermal heat exchange has been steadily increasing during the last decade, yet there are still pending questions on their behavior during temperature changes. This paper focuses on the thermo-mechanical response of three full-scale energy piles installed in Richmond, TX. The behavior of test piles subjected to thermo-mechanical loadings was studied in situ with the aim of quantifying the thermal influence on the performance and capacity of energy piles. An extensive field test program, including conventional pile loading tests and application of heating-cooling cycles was conducted on the test piles during a period of six weeks. For thermal load applications, the heat exchanger fluid with maximum temperature of 113°F (45°C) and minimum of 47°F (8°C) was circulated in the geothermal loops placed at the center of the test piles. Optical fiber sensors, vibrating wire strain gages, thermistors and thermal integrity profile wires were installed to monitor the strain and temperature variations along the energy piles throughout the field tests. The strain and temperature profiles during heating-cooling cycles on the test piles under static loads and without a maintained load were monitored to investigate the effect of thermo-mechanical and pure thermal loads on the energy piles, respectively. Conventional pile load tests were applied before and after the application of thermal cycles. The results of the pile load tests are compared to evaluate the effect of temperature cycles on pile capacity.IntroductionEnergy piles are deep foundation elements designed to access and exploit the relatively constant temperature of the ground and its heat storage capacity for efficient heating and cooling of buildings. The deep foundation elements that are already in place for structural support are integrated with adsorber pipes to perform as heat exchangers connected to ground source heat pump (GSHP) systems. With the use of energy piles, the heat energy is fed into and withdrawn from the ground for cooling in the summer and heating in the winter, respectively.Energy piles present an innovative way to harvest near-surface geothermal energy and to provide lower carbon emissions, however, there are still pending question on their performance. During heating-cooling cycles, energy piles experience temperature changes, which result in expansion or contraction of the piles."

Jan 1, 2017

By RavikiranVaidya, Vishal Dhamecha

Low Strain Pile Integrity Testing has been used in India since 1990’s and several have tried to demonstrate the utility and benefits of this method. However, use of this technology was limited till 1998 as not enough data maybe was not available to justify its use and application on major infrastructure and real estate projects. The first author has done significant work in this method resulting in its use in practically all sectors of the industry that use concrete bored pile foundations as a supporting element. The paper explains various signal enhancers or modifiers involved in processing of low strain test data and its implication on the final output. It also describes how the method can lead to abuse or can provide poor interpretation if incorrectly used. The current effort is to demonstrate that data collection and evaluation becomes complex with changes in soil stratum and pile profile. The paper highlights the present testing practices and provides a guideline for classification of pile integrity into few simple categories in Indian context rather than writing complex interpretations.

Sep 1, 2022

By James S. Graham

Research at the University of Colorado on southern pine and Douglas-fir piling has determined that the existing building code design stress values of 1200 psi and 1250 psi, as determined by ASTM D-2899, are substantiated; but testing procedures should be revised. All full size piling tests should be standardized at 1/d ratios of 2:1, or confined tests performed. Also, it has been determined that theoretical design values for timber piling should not be based on the lumber criteria of D-245 and D-2555, but instead should follow the pattern set by engineers in the utility industry for timber poles, in accordance with ANSI 05.1.

Jan 1, 1986

By Bill Shea, Gordon King

"For a drainage channel built in San Juan, Puerto Rico, a value engineering (VE) proposal incorporating a secant pile top-down approach saved time and facilitated construction work on the larger flood control project. The channel, at the Bechara Industrial Area, Puerto Nuevo Port Facility and the Puerto Rico Maritime Shipping Authority Dock, was needed to allow drainage of the Rio Puerto Nuevo into San Juan Bay. The port area, one of the busiest in the Caribbean, has over 6,000 ft (1,800 m) of berthing wharves for ocean-going container ships along with over 500,000 sq ft (46,000 m²) of container loading and unloading areas, and is critical to the local economy.Planners wanted to minimize the impact of construction to the port and dock users, and developed a construction methodology and work sequencing that would prevent a complete barrier to port traffic. This plan involved non-contiguous and limited work area that “leapfrogged” along the alignment so as to prevent long barriers to lateral traffic movement across the culvert alignment.After reviewing the project plans and schedule, Morris-Shea Bridge Company (MSB) proposed an alternate design and construction approach that provided significant cost and schedule benefits, and also provided better access for the port and dock users. The alternate VE proposal involved top-down construction methodology and redesigned drainage culvert geometry with two parallel 2,000 linear ft (lf) (600 m) secant walls installed on each side of the culvert. These walls facilitated excavation and formed part of the culvert permanent walls. The result was a significantly reduced required construction right of way that allowed construction work in contiguous areas largely without impact on ongoing port activity. MSB conceived the design concept, and engineered design and construction of the VE alternate secant pile culvert.The project initially consisted of an open channel in the industrial area picking up water from the existing Rio Puerto Nuevo, transitioning to an enclosed culvert through the port and dock areas, and outfall through the existing dock. The base bid construction included three main areas of work:"

Jan 1, 2012

By Yazn Khasawneh Ph. D. P. E., Will Tjaden, Spencer E. Ness P. E., Mohammed Nasim Ph. D. P. E.

Wind turbine components undergo many loading cycles during their operational life. Additionally, wind turbines may undergo extreme loading conditions from natural hazards, mechanical failures, or emergency stops. Current design practice for the foundations of wind turbines accounts for these complex loading conditions through a simplified pseudo-static approach based structural loading combinations. A rotational stiffness for the foundation is estimated from the pseudo-static analysis and then compared to an acceptable minimum rotational stiffness provided by the turbine manufacturer. These minimum rotational stiffnesses are based on dynamic analysis of the tower and nacelle system with the foundation represented as linear springs. This approach provides a reasonable approach to the foundation design but does not accurately capture the true dynamic performance of the entire soil-foundation-tower-nacelle system. This becomes especially important for pier-type foundations, which are being more commonly used to support modern and future generations of larger turbines. Additionally, the dynamic performance of the foundation will vary as the adjacent soil undergoes a large number of loading cycles of varying strain magnitudes. In this study, the full turbine-tower-foundation-soil system was modeled using finite element methods. An advanced non-linear soil constitutive model and dynamic loading time histories were used to investigate changes in stiffness of the soil, and the possible impact on the dynamic response of the system. Results were compared to conventional design methodologies with the goal of reducing foundation capital costs while avoiding increases in O&M costs and which can lower the LCOE of wind energy.

Oct 1, 2022

By D. A. Bruce

The use of small diameter cast-in-place bored piles is becoming increasingly popular in the United States. Such inserts are used as conventional load bearing piles, and are generally referred to as pin piles. The other major application is for the in situ reinforcement of soil slopes or excavations. The paper reviews the applications, construction, design and performance of inserts of each type.

Jan 1, 1989

By Bengt H. Fellenius

"ABSTRACTAn example from a guidelines document for the Eurocode is discussed that addresses design for geotechnical strength of piled foundations in settling soil, generating drag force and downdrag. A modified example of geotechnical response is then analyzed in a failure mode, Ultimate Limit States (ULS), and stationary long-term state, Serviceable Limit States (SLS). It is shown that the Eurocode principles, when applied to correctly determined forces, results in an irrational and costly design. The results of the analysis of the modified example are applied to eight different codes pertaining to piled foundations from USA, Canada, Europe, and other countries. Several of the codes require that the drag force be included as a load in a ULS design, which an absurd and costly requirement, in some codes, in one case made even worse by combining drag force with live load. A major weakness of almost all codes is their minimal treatment and sometimes total absence of aspects of settlement of piled foundation. In contrast, my main argument is that design for capacity, whether in working stress approach, or by LFRD or ULS approaches, is not always safe unless a thorough settlement analysis shows that the design also meets the requirements of the SLS.1. INTRODUCTIONFirst, there were analysis, design, and construction establishing a State-of-Practice, SOP. Then, came codes and specifications summarizing the SOP, as interpreted by a committee. When the state-of-art, SOA, was not understood by that SOP-interpreting committee, the codes and specifications are uneconomical and, sometimes, also unsafe.The paper first presents an example quoted from two commentaries on the Eurocode 7 on design for geotechnical strength by the Eurocode (1997). The example is then modified to a more realistic case and analyzed in failure mode (ultimate limit states, ULS) and in the context of settlement (serviceability limit states, SLS). The analysis results are then applied to eight codes addressing piled foundation design and changes necessary for the referenced codes and specifications to be closer to the SOA are identified."

Jan 1, 2014

By Anthony T. C. Goh

"For deep excavations in soft clay, it is common to use jet grouting piles (JGP) prior to excavation to minimize wall deflections and ground settlement, and to prevent basal heave instability. In this paper, finite element analyses were carried out to assess the basal heave factor of safety for excavations in soft clay supported by JGP. Comparison of the factor of safety from the finite element analyses with limit equilibrium methods was then performed. Subsequently, to account for the uncertainties in the soil and JGP properties, a simplified reliability analysis procedure is proposed to estimate the probability of basal heave failure for deep excavations supported by JGP.INTRODUCTIONJet grout piles (JGP) are often used to prevent basal heave instability and to minimize excessive wall and ground movements associated with deep excavations in soft clay deposits (Shirlaw 2003; Wen 2005; Ou 2006). The jet grouting process which is carried out prior to any excavation works produces a series of short overlapping grout columns resulting in a “continuous” base slab (commonly termed as jet grout pile or JGP) below the final excavation level that spans across the entire excavation (Gaba 1990; Hsieh et al. 2003; Ho and Hu 2006). Typically, the JGP thickness ranges from 2 m to 4 m.The focus of this paper is on the assessment of basal heave instability for deep excavations in clay stabilized with JGP. Finite element analyses were first conducted to determine the basal heave factor of safety for deep excavations in clay with JGP. Comparisons were then carried out with factors of safety based on conventional limit equilibrium methods. Since the conventional factor of safety approach does not explicitly reflect the uncertainties of the soil and JGP properties, it is demonstrated in this paper that a simple reliability based approach (Hasofer and Lind 1974) can be used to assess the probability of basal heave failure.LIMIT EQUILIBRIUM METHODFor excavations is clay, the Terzaghi (1943), Bjerrum and Eide (1956) and Eide et al. (1972) methods which are based on bearing capacity theory, are commonly used to determine the basal heave factor of safety. Another commonly adopted method in Japan and Taiwan is the slip circle method which involves taking moments about the lowest strut level (JSA 1988; Hsieh et al. 2008; Luo et al. 2012). The slip circle method has also been applied for excavations with a JGP at the base by incorporating the undrained shear strength of the JGP. In the slip circle method, the basal heave factor of safety FSslip is assessed by taking moments about the lowest strut level (Fig. 1)"

Jan 1, 1900

By Scott A. Walker, Gabriel J. Alcantar, Brian Zuckerman, Ramin Golesorkhi

"The stadium development consists of construction of a 68,500-seat, open-air NFL football stadium for the San Francisco 49ers. The main structure will consist of a 7-story above grade steel structure supported by over 3,000 piles. Berkel and Company Contractors, Inc. (Berkel) was selected as the design-build pile contractor who used their auger pressure grouted displacement (APGD) piles for this project. During an indicator pile installation and pile load test program, fifteen piles were tested to develop installation criteria to support demands of 150kips tension and 180 kips compression. Following the indicator pile program Berkel installed 3088 piles in 30 working days. Throughout pile installation data were collected with an automated data acquisition system (DAS). During pile installation field engineers from Treadwell & Rollo observed the pile installation as well as the real-time data from the DAS. Strategic staging and pre-production planning by Berkel along with consistent collaboration with the design team created an atmosphere for a successful and on schedule project completion.IntroductionThe new San Francisco 49ers Stadium in Santa Clara, California will be a 68,500-seat facility, a rendering of which is shown in Figure 1. The main structure will consist of a 7-story above grade steel structure supported by more than 3,000 piles. The north, east and south portions of the stadium are designed as an open seating bowl, while the western portion includes open seating at the lower levels and seven-story tower which houses over 150 suites.The stadium project includes the stadium structure, as well as elevated open pedestrian walkways, commercial community space, and three new pedestrian bridges spanning a nearby by creek. Sustainable designs and innovations such as a green roof, photovoltaic panels, a ground source geothermal system, stadium-wide Wi-Fi capability, and access to public transit are provided throughout the project. The stadium is designed as an open, light, and airy structure and is surrounded by an existing amusement park, office buildings, the Santa Clara Convention Center, and the training facility of the 49ers."

Jan 1, 2015

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