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By Steve Davidow, Ashely E. Evans, Peter M. Kandaris

"Annually thousands of deep foundations are constructed across North America supporting high voltage transmission line structures. However, a recent state of the practice survey by the Deep Foundation Institutes’ Electric Power Systems Foundation Working Group discovered that the electric power utility industry lacks consistent foundation design guidelines. The survey identified a wide variability in design assumptions, a minimal understanding of risk based analysis, and a need to standardize design methodologies. This paper summarizes the state of practice in electric system foundation design and proposes a framework for risk-based foundation design by accounting for uncertainty from both loads and resistances. Loads derived from electric system codes do not necessarily provide a compatible level of reliability for the design of foundations, as they are a mixture of probabilistic and deterministic values. Load uncertainty is derived from variability in weather conditions, structural models and material properties, typically accounted for by code derived overload factors. Resistance uncertainty arises from variability in natural soil properties, resistance models, subsurface construction techniques, material sampling methods, and limited observations. A consistent methodology is offered relating nominal resistance capacity (strength) to structure loads and service state criteria. Discussion also includes the need for risk-based assessments to account for non-structure load influences (fluvial loads, scour ground loss, liquefaction, etc.).INTRODUCTIONNearly 40 years ago the Electric Power Research Institute (EPRI) embarked on a major research effort to optimize reliability and economics of transmission line foundation design. Strategies focused on improvements in design models, site characterization, exploration strategies and testing to reduce uncertainty and variance in analysis. Transmission line engineers realized that safety and reliability advancements in design based on probabilistic approaches, with a focus on the unique nature of transmission line, could better control risk and cost.Some transmission line professionals took full advantage of these advancements, particularly where research led to improved software and models. Yet, even after two decades of extensive research, by 1995 the industry still had made little progress in changing design habits. The majority of designers were still characterizing sites via deterministic methods, using loads that may or may not relate to a consistent probability of occurrence, and applying a traditional global factor of safety approach (Phoon, et al. 1995). The following two decades have seen even greater developments in software and reliability-based analysis methods, but old habits seem to die hard as recent surveys show less than half of design professional quantitatively assess risk in their design process."

Jan 1, 2017

By W. L. Chong, Y. Zou

There are many types of Earth Retention Systems (ERS) available in the market where more than one method can be a feasible solution for a project. This paper examines the design and construct process of a project in Dee Why, NSW using a hybrid ERS comprising contiguous piles with jet grout infill. The development comprises a deep basement and mixed-use urban superstructure. The site is located in an area of variable ground conditions, high ground water table and in proximity to existing buildings with multi-level basements. This paper details a comprehensive assessment of the geological conditions and strategies adopted to better understand the effectiveness of the proposed product and to minimise the associated risks of the proposed solution. This involved conducting additional geotechnical investigation, extensive numerical modelling and in-situ monitoring of the movements and the performance of the walls. A monitoring regime consisting of inclinometers, survey points on capping beam and prisms on the neighbouring buildings and roads surrounding shoring wall was implemented. The monitoring results were back-analysed using computer software WALLAP, Plaxis–2D and Plaxis–3D for the post-construction examinations. This paper details the effectiveness and advantages of a hybrid ERS using contiguous piles with jet grout infill.

Nov 1, 2022

By Ziyad Abunada, David O’Connor, Fei Jin, Abir Al-Tabbaa

"In-situ remediation of contaminated land with deep mixing can enable a multi-technique remedial strategy on the same site combining low permeability barriers, permeable reactive barriers, stabilisation/ solidification treatments as well as ground improvement, delivering significant advantages over alternative strategies. This was the core objective of Project SMiRT (Soil Mix Remediation Technology) which involved the execution of the largest research field trials in the UK to date to provide field validation for this technique. Around 800m3 of soil were treated on a contaminated site in Yorkshire in May 2011 with 6 different treatments, testing ~40 binder compositions and 10 different installation methodologies. Field monitoring, testing and coring activities at the site took place within the first 2 months after treatment and then again at 34 months after treatment. This paper presents an overview of the field activities to date and some 3-year results and assessment of a subset of the treated soil sections. Some good correlations are seen together with some clear differences between treatments. There is generally an observed consistency with depth, with the mixing effectiveness having a more profound effect than the binder composition or content, within the tested materials and ranges. These field trial activities are currently being used in the development of the full-scale commercial remedial strategy for the site.INTRODUCTION AND OVERVIEW OF PROJECT SMiRTWhile there are strong financial and environmental incentives to remediate and redevelop brownfield sites there are also barriers including fear of the unknown, regulatory control, delays, increased costs and the stigma associated with such sites. Hence the remediation process needs to be conducted in such a way to maximise the incentives and overcome the barriers, which is how deep mixing found its niche in the land remediation market. Soil mix technology is such a versatile technique that can perform a number of remediation treatments on the same site. These include low permeability in-ground barriers (cut-off walls), permeable reactive barriers (PRB), stabilisation/solidification (S/S) treatments, other additive related remediation, e.g. in-situ chemical oxidation and bioremediation, as well as soil amendments for greening and also ground improvement all on the same site (Al-Tabbaa et al, 2011). Placed in the context of alternative solutions, soil mix technology could potentially replace the five techniques shown in Figure 1, which would be required to deliver the same treatments mentioned above. Treatment trains strategy, where a combination of techniques in succession are used to both reduce the contamination levels and deal with residual contamination, is becoming common in land remediation and the use of one set of equipment to deliver this would bring about significant financial advantages. In addition, soil mix technology has many other advantages in terms of speed of implementation, elimination of exposure to contamination, elimination of off-site disposal and low cost. Soil mix technology for the remediation of contaminated land emerged in the UK in the mid 1980s and has since been employed in over 30 or so projects, which far exceeds its application to ground improvement for which only a handful of jobs have been carried out to date."

Jan 1, 2015

By Hayel M. El-Naggar, Mohamed Sobhi, Mamdouh M. Hamza, Marawan M. Shahien

"This paper presents the results of two lateral load tests on large bored piles in soft clay deposit for a major site in northern Egypt. The tests are carried out on 0.8 m diameter piles. One of the tests is carried out on the pile where the clay starts from the ground surface. The other test is carried out on a pile after surface improvement by replacing the top 1.50 m of the clay deposit by compacted granular soil. The results of the tests show the influence of the surface replacement layer on the lateral load versus lateral displacement relationships of the loaded pile. The results of the two tests are used to calibrate a 3D Finite Element Analysis model for the pile. The model is used to investigate the influence of the thickness and lateral extent of the surface replacement layer on the behavior of laterally loaded large bored piles.INTRODUCTIONLateral loads for piles are produced by seismic events, wind, wave action, ship impact, traffic, and land slide forces. The lateral resistance of a pile is controlled by the stiffness and the strength of the material of the pile and the soil surrounding the upper portion of the pile. In most situations, the soil surrounding the upper portion of the pile is too weak to sustain the design lateral loads. Thus there is a need to increase the lateral resistance of the pile or groups of piles. Such an increase may be achieved by either increase number of piles or increase pile diameter. Alternatively, an economic way to increase the lateral resistance is to improve the soil surrounding the upper portion of the pile (Rollins and Brown, 2011; Faro et al., 2015).Ground improvement has the ability to increase the lateral resistance of the pile by increasing the passive resistance of the soil surrounding the upper portion of the pile. The ground improvement techniques have the potential for being more cost-effective and reducing construction time. In spite of this fact, such techniques are rarely implemented in practice. Further, there are relatively few tests or records available in the literature to guide engineers in evaluating the actual effectiveness of this approach. In addition, there is no standard or methodology to aid engineers in designing increase of lateral resistance with surface ground improvement. There are specific improvement methods for each soil type, whether it is loose cohesionless soil or soft cohesive soil and these methods are provided by Michell (1981), Tershai and Juran (2000), ASCE (1997), and Rollins and Brown (2011). Furthermore, there are number of case histories that add a new hole in the sight, such as the cases provided by Brown et al. (1987, 1988), Mokwa and Duncan (2001), Rollins et al. (2005), Rollins and Cole (2006), Cole and Rollins (2006), Rollins, Snyder et al. (2010) , Rollins, Gerber, and Kwon (2010), Rollins and Nasr (2010), and Gerber et al. (2010)."

Jan 1, 2016

By Haijian Fan

Currently, deep foundation designs for the service limit state are deterministic in nature. The settlements and lateral deflections of deep foundations are calculated by means of numerical techniques whereby the foundation-soil interactions are characterized by discrete load transfer curves such as t-z or p-y curves. The noted deficiency of the deterministic approach is that the uncertainties arising from various sources, such as soil properties and model errors are not considered. To address this deficiency, a performance-based reliability design methodology is developed using Monte Carlo statistical methods. The performance based design criteria are defined in terms of the specified allowable displacement. The input to the numerical solution techniques, including the soil strength parameters, unit weight of the soil are relevant to the generation of the load transfer curves are treated as random field. The well established random field generator algorithm, local averaging subdivision, is used to generate random samples of input, where the mean values, variances, the probability distribution, and correlation structures are required statistical parameters for these random variables. The objective of the performance based reliability design is to determine the optimized foundation dimensions so that the probability of failure is less than the target probability of failure. The probability of failure by the Monte Carlo approach is simply the ratio of the number of unsatisfactory performance to the sample size. A numerical example for laterally loaded drilled shaft is given to illustrate the application of the methodology. The incorporation of the correlation length is shown to be critical for properly accounting for the site soil spatial variability.

Jan 1, 2017

By Haijian Fan

Currently, deep foundation designs for the service limit state are deterministic in nature. The settlements and lateral deflections of deep foundations are calculated by means of numerical techniques whereby the foundation-soil interactions are characterized by discrete load transfer curves such as t-z or p-y curves. The noted deficiency of the deterministic approach is that the uncertainties arising from various sources, such as soil properties and model errors are not considered. To address this deficiency, a performance-based reliability design methodology is developed using Monte Carlo statistical methods. The performance based design criteria are defined in terms of the specified allowable displacement. The input to the numerical solution techniques, including the soil strength parameters, unit weight of the soil are relevant to the generation of the load transfer curves are treated as random field. The well established random field generator algorithm, local averaging subdivision, is used to generate random samples of input, where the mean values, variances, the probability distribution, and correlation structures are required statistical parameters for these random variables. The objective of the performance based reliability design is to determine the optimized foundation dimensions so that the probability of failure is less than the target probability of failure. The probability of failure by the Monte Carlo approach is simply the ratio of the number of unsatisfactory performance to the sample size. A numerical example for laterally loaded drilled shaft is given to illustrate the application of the methodology. The incorporation of the correlation length is shown to be critical for properly accounting for the site soil spatial variability.

By Abdulazeez Rotimi, Barry Sheppard, Abid Adekunte

Good engineering practice is a function of sound theoretical knowledge, first-hand experience on previous projects of similar scope and scale, good acquaintance with case histories of similar projects completed by others in similar environmental conditions, as well as satisfactory degree of exposure to state-of-the-art methodologies. The four factors itemised above are typically interdependent. They amalgamatively influence the judgement of the Engineer and they ultimately result in the delivery of safe and cost-effective solutions by Professional Engineers. This technical paper presents detailed information on the ground engineering aspects of a large-scale housing development project located on a sloping site that had been presumed to be unstable in West Sussex, England. The ground engineering design package for the scheme comprised of temporary working platform designs & stability assessment for piling rigs and other construction machinery, geostructural designs for approximately 1km total run of permanent bored pile retaining walls to support the split-level construction on the sloping site and geostructural designs for the permanent foundation piles to support the housing units. The paper details how the four factors outlined above were amalgamated by the project’s foundation specialist consultants & piling contractors to deliver safe and practical solutions for the development, with significant savings in materials, cost and project completion time.

Sep 8, 2021

By Yan Lap J. Kan

"A waterfront stabilization system consisting of Deep Soil Mixing (DSM) columns, vinyl sheet pile fascia, and concrete flood walls supported on shallow footings was designed and constructed for a high-density waterfront development in Northern California. The project site is underlain by soft, compressible organic soil locally known as Bay Mud that has been capped with loose sand and imported fill. The waterfront stabilization system constructed at the site mitigates liquefaction, consolidation settlement and seismic potential slope deformation along the waterfront; the system was designed to reduce lateral displacements to tolerable amounts for the proposed structures. This paper presents the general design methodologies, construction challenges and quality control of this waterfront stabilization system.INTRODUCTIONUrban development in Northern California is fueling innovations in geotechnical engineering as more complex sites are developed. ENGEO Incorporated introduced a deep soil mixing technology from Japan to the US and designed a waterfront stabilization system for a high density waterfront development project in Redwood City, California. The approximately 12½-acre project site, as shown on Fig. 1, is surrounded by water on three sides, with an inner marina at the center of the site.The project site is located in the seismically active San Francisco Bay Area in California. The San Andreas Fault, the Monte Vista-Shannon Fault, the Hayward Fault and the San Gregorio Fault are major active faults located within 25 miles of the site. Once a former marshland with a major slough until the late 1950s, the site was reclaimed by placing imported fill over the native compressible clay deposits, locally known as Bay Mud."

Jan 1, 2016

By James M. Tantalla, Dwight Metcalf, Roderic A. Ellman Jr.

"The construction of a new low head hydro-electric plant at the Cannelton Lock and Dam required the design and construction of a cofferdam to accommodate a deep excavation extending approximately 150 feet below the Ohio River levels. The new plant, which generates about 390 GWh of electricity annually, is owned by American Municipal Power (AMP). A specialist team was assembled to design and construct the cofferdam, marine dike and CB slurry wall that helped make the project successful and on time for project delivery.Because the new plant diverts water from the locks and dam through a powerhouse to generate power, it would need to be partially in the river to operate properly. To accomplish this, approximately 250,000 square feet of land was reclaimed from the river by construction of a marine dike. The dike, combined with the design and construction of a 150 foot deep cement bentonite (CB) cutoff wall enabled construction of the new plant in the dry. Extensive dewatering analyses were performed using Modflow to evaluate pumping requirements and the number of wells needed to maintain ground water at required levels within the side slopes and final subgrade. A monitoring program consisting of inclinometers, piezometers and movement monitoring points were used to monitor cofferdam stability and performance throughout construction. Detailed two and three dimensional stability analyses that included a parametric study of fluctuating river levels and slurry unit weight were performed to ensure stability and suitable low permeability of the trench during cut-off wall excavation both on land and in the marine dike. The wall was constructed with both a hydromill excavating primary panels and a clamshell following behind to construct secondary panels. Data acquisition systems onboard the excavating equipment allowed for detailed confirmation of the continuity of the wall at each interface between panels. Another challenging aspect was the CB mix design for the trench. The cofferdam required the construction of a 1,300-foot long marine dike downstream of the existing dam up to 100 feet tall founded on existing river sediment to enclose the site and cut-off the seepage into the excavation from the river. Marine dike construction utilized vibro-compaction to pre-densify granular fills placed underwater through which the CB trench extended."

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

By Douglas R. Hardin, Stanley L. Worst, Joanna Mason

A challenging earth retention project presented itself in Washington, DC in the backyard of the historic House of the Temple (The Scottish Rite of Freemasonry, Supreme Council 33°). Located at 15th St NW and S St NW, a forty-foot-deep underground basement was to be installed adjacent to the existing Temple, a historic Carriage House structure dating back to the 1800’s and across a narrow alley from a four-story brick apartment building. The unique geology of the site included typical urban fill overlying a mixture of loose alluvial soils underlaid by dense marine deposits of the Potomac Formation. The clay, sand and gravel of the Potomac included nested boulders up to three feet in diameter. Design of the earth retention system accounted for ground conditions, installation methods and estimated movement of the system and adjacent structures. Anticipated ground water and unanticipated water from leaky sewers also proved obstacles to overcome during construction. Soldier beams were installed using a variable momentvibratory hammer to minimize disturbance to the historic and sensitive structures. Monitoring of the existing structures included both seismograph and optical targets during installation of soldier beams and as the excavation progressed. Micropiles drilled into the Potomac Formation were a part of the permanent foundation for the new structure. This local case history will delve into the details of the successful design, installation, and performance of an earth retention system and micropiles in a historic and highly congested urban environment.

Oct 1, 2022

By D. Y. Peng

A Large Sub-structure with open top of S.Y.P. float line requires a 90m x 50m in plan and 13m-deep excavation in soft soil, Shanghai. The geological conditions in site are rather severe. The technology specifies that no permanent braces nor partition walls are allowed to be constructed inside. After a series of discussions the scheme of semi-gravity type cellular D-walling without any braces or earth anchors is finally adopted and successfully executed by SFEC. This paper deals with the technical problems in the design, construction and in-situ monitoring we met with in this difficult project.

Jan 1, 2010

By James C. Scott

Compression and tension load testing were performed on bored concrete piles installed to depths of 18 to 34 meters below excavation levels for a large mixed-use development in Kuala Lumpur, Malaysia. The 900 mm diameter piles were installed in weathered graphitic schist bedrock. Load testing confirmed the side shear and end bearing capacities of the piles. The work formed part of the investigations for the 56,000 m2 site which includes a 79-story office tower, hotel tower, apartment tower, retail complex, and plaza area underlain by 4 to 6 basement levels. The paper provides the results of the site investigations, pile-load testing procedures, pile-load settlement behavior, and shaft load distribution.

Jan 1, 2007

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Rakam Lama Tamang, Michael J. Byle, Stephen Ernst

"For various reasons, dredging may become necessary in front of existing bulkhead walls, either for channel deepening or for environmental remediation of contaminated sediments. The removal of sediments at the base of bulkhead walls removes support for the toe of the wall that must be assessed. Evaluation of this impact can be problematic for aging bulkheads for which no design or construction records exist. This paper will address the steps that should be taken in investigation and analysis to assure proper assessment and means to address uncertainties and gaps in information. The steps include pre-investigation data review, field inspection, geotechnical and geophysical investigation tools, parametric analysis and design tools. Examples from several bulkhead assessment projects will be provided that include a variety of conditions and tools for application. The focus of the paper will be on the integration of technologies to assess bulkhead geometry, geotechnical properties and stability, structural safety and constructability issues with removal of support, and means of temporary and permanent stabilization for environmental applications.IntroductionBulkheads and quays have existed as long as there have been waterfront activities. Some of the earliest date back to 1200 B.C.E.(Raban, 1987), however in the United States few predate the eighteenth century. Most extant bulkhead structures, and all steel sheet pile bulkhead walls date from the early 20th century or later. These structures function to protect the shore from erosion, support landside activities, and serve as place to moor and offload vessels. Regardless of the age or usage of existing bulkheads, it is essential to assess and protect them if needed where removal of soils on the water side of the bulkheads is planned to dredging.Waterfront BulkheadsExisting bulkhead structures can be classified into two types: Cantilevered, and anchored. Cantilevered walls are completely supported by the soil on the water side, while anchored bulkheads are supported both by the soil on the water side and anchorage on the land side (Figure 1). Walls may be constructed of timber, steel, or concrete. Timber walls may be lagging with soldier piles, cribbing with soldier piles, or timber sheeted such as Wakefield walls (Figure 2). Steel bulkheads are most commonly constructed using sheet piling comprised of interlocking A or Z shapes, though some historic walls were constructed with flat sheets. Precast concrete sheet piling has also been used in construction of bulkhead walls. Anchorage may be provided by steel bars or tendons attached to deadmen, sheet piling, driven piles, or earth anchors."

Jan 1, 2017

By Kenneth Gavin, Weichao Li, Paul Doherty

"The lateral load capacity is one of the most important issues to be considered in designing piles to resist berthing loads, ship impact forces and for monopiles used in the offshore wind sector. A number of semi-empirical design approaches are available to calculate the ultimate soil resistance and assumed soil reaction profile along the piles’ embedded depth. In order to investigate the response of monopiles to lateral loading, a series of field experiments were conducted on instrumented steel pipe piles. Two lateral loading tests were performed on model piles with a diameter, D, of 340 mm and embedded depth, Lem, of 2.2 m, giving a Lem/D ratio similar to those adopted in the offshore wind sector. The piles were driven into dense sand at the University College Dublin geotechnical test bed site in Ireland. 10 pairs of strain gauges were installed on each model pile along the embedded depth at 10 levels to capture the load transfer and bending moment within the piles. The deflection and rotation at the model pile head were measured by Linear Variable Differential Transformer (LVDT) and inclinometers. The tests results were used to perform a detailed evaluation of current design methods. In the final section, discussion on the determination of the ultimate lateral load capacity for monopile design was conducted. IntroductionA pile’s lateral load capacity is determined, for design purposes, by two conditions: 1) the ultimate lateral load, Fu, divided by an appropriate safety factor; and 2) the load according to the maximum lateral deflection that the support structures can sustain. In view of the first condition, design methods to calculate the ultimate load were developed for piles used in the offshore oil and gas sectors, which tend to be much more slender than monopiles used in the wind industry. The purpose of this study was to investigate whether these design methods provide reasonable estimates of ultimate capacity, for short rigid monopiles.The methods to determine the ultimate lateral load generally follow three steps: 1) determine the ultimate soil resistance, Pu, along the pile embedded depth; 2) adopt the most appropriate soil reaction profile, Pz, along the piles embedded depth when the pile subjected to the ultimate lateral load condition (four of the most popular ones are depicted in Figure. 1); and 3) ensure equilibrium of lateral forces (see Equation 1, symbols are listed at the end of the paper) acting on the pile and bending moments (see Equation 2) about a point in pile is employed to determine the ultimate lateral load."

Jan 1, 2015

By A. Ortigão, M. Felix, E. Falk, T. Koehler

"Ground improvement techniques such as vibro-replacement or deep soil mixing are fairly young products in the Brazilian geotechnical market. Soft soils in this country are deep, very soft, have low sensitivity and are challenging. In general, ground improvement techniques are increasingly selected as more costefficient and flexible solutions on infrastructure projects compared to the conventionall technologies such as piled embankments, wickdrains with surcharge or jet-grouting. The geotechnical challenge expansion project for the Porto Alegre Airport, South Brazil, involved a taxiway area of five ha of 8 to 10 m of soft clay deposit. The deep soil mixing (DSM) technique was selected as a cost-effective solution to reduce settlements. As part of the design, an extensive soil investigation programme includ ing laboratory and field trials was carried out to define the most economical slurry-recipe, DSM installation patterns and quality control specs. This paper gives details of the field and laboratory trials and present results.INTRODUCTIONThe International Airport of Porto Alegre in the state of Rio Grande do Sul in Brazil is located in an area with extensive sediments near to Guaíba Bay. During the different construction phases of the airport over the last decades, the soft clay deposits have been a challenge for the local geotechnical community as well as for the specialized contractors (Schnaid et al, 2001). As part of the most recent expansion scheme, a cargo-terminal with a five ha airplane tarmac area will be constructed."

Jan 1, 2015

By Garland Likins

High strain PDA testing has become common for verification of capacity of both driven and bored piles. It is equally applicable to Augered-Cast-in-Place (ACIP) Piles. It also evaluates other aspects of the installation such as integrity. The benefit of high strain dynamic test results for the relatively low cost of the tests compared to conventional static testing has resulted in widespread use. The method is described and specific procedures for testing ACIP piles are outlined. Example results demonstrate the application.

Jan 1, 2000

By Michael T. Lambert

The purpose of the this paper is to demonstrate the benefits of using additional instrumentation during load tests of auger-cast-in-place piles. Traditionally, only load and butt displacement are determined during load tests. The results from and methods used to instrument 15 auger-cast-in-place (ACEP) piles as part of six projects are included herein. By instrumenting the piles, the distribution of load along the pile length and load transfer can be determined, allowing the pile capacity to be adjusted or the length/diameter of the pile to be adjusted for the a given required load. The majority of the piles tested were designed as end bearing piles on either shale or limestone bedrock. No discussion of Geotechnical Instrumentation can be started without acknowledgement of the "Red Book." The actual title of the book is Geotechnical Instrumentation for Monitoring Field Performance, by Mr. John Dunnicliff, John Wiley and Sons, 1993. Anyone undertaking an instrumentation program should thoroughly review the Red Book, paying particular attention to Chapters 3 and 4. Instrumentation should not be done just because it can be done. There must be an unanswered question or questions that can be answered with measured data before instrumentation should be considered.

Jan 1, 2000

By Dongwook Kim

Recently, load and resistance factor design (LRFD) is gradually being adopted internationally in geotechnical design due to the advantages of LRFD over the existing allowable stress design (ASD). LRFD is a more advanced design method compared to the ASD because resistance factor is calibrated based on the reliability analysis for a given target reliability index. Target reliability index changes with the importance of the structure. Typically, target reliability index of offshore foundation is less than those of onshore. The widely-used Imperial College Pile (ICP) design method is used for the calculation of pullout capacity of driven piles. The uncertainties regarding pullout capacities of driven piles are assessed using the statistical data reported in the literature. The first-order reliability method (FORM) is used to calibrate resistance factors for the pullout ultimate limit states of the driven piles for three different levels (2.5, 3.0, and 3.5) of target reliability index. The load factors used in this paper are the ones proposed in the AASHTO LRFD bridge design specifications.

Jan 1, 2010