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By Omer F. Usluogullari, C. Vipulanandan

"It is critical to monitor the ground conditions during excavation and drilling of boreholes during construction to identify possible changes in the soil and rock formations. Drilled shafts are increasingly used as foundations to support structures, bridges and other facilities in geomaterials such as soft-rocks and hard clays. Locating the bottom of the borehole during construction with the required design strength is critical. Hence developing a simple device that could be easily adapted/used with the drilling tool was of interest in this study. Determining the shear strength of the geomaterial in the borehole and at various elevations including the bottom of the borehole can lead to better quality control of construction by identifying the various layers based on strength.In this study, a down-hole penetrometer (DHP-CIGMAT) was designed, built, calibrated and tested in the field to determine its effectiveness in measuring the strength of soil/soft rock in the boreholes. Based on limited field tests, linear correlations between geomaterial strengths and DHP-CIGMAT deflection have been developed. The DHP-CIGMAT can be used to identify soils and soft rocks.IntroductionIn-situ tests are increasingly used to determine the soil properties for geotechnical analysis and design of deep foundations (Ampadu and Arthur 2006; Hsu and Huang 1999). Static and dynamic penetration resistances have been used to classify and characterize subsoil (Ahmadi et al. 2005). The penetrometers evolved from the need of acquiring data on subsurface soils that could not be easily sampled by any other method. Laboratory testing undisturbed samples requires great care to avoid disturbance during handling, or systematical disturbance during testing, and it may be difficult to relate the laboratory test results to the in-situ properties of the soil (Sanglerat 1972). There is always a certain degree of disturbance to the samples because the confining pressures, which exist in the ground, are forcibly changed when the sample is collected."

Jan 1, 2017

By Ashraf M. Eid

Most research dealing with the problem of laterally loaded piles has been the response of individual piles subjected to lateral loads and/or bending moments. However, piles are seldom used individually but are normally constructed in clusters or groups. Little information is available of the effect of pile-soil-pile interaction (PSPI) on the performance of the group. This may be attributed to the difficulty of carrying out full-scale tests. Such tests are prohibitively expensive and require special installations to provide the required large lateral loads. The problem of laterally loaded single piles or pile groups involves the complexity of extending the theoretical solutions to the limits where the actual soil behaves nonlinearly. As the load increases, the elastic soil behavior cannot be adopted for design. Nonlinear soil behavior or the elasto-plastic behavior is evident. This research consists of experimental and theoretical models. The experimental work was conducted on models of free head pile groups in different configurations. The piles were in a sand formation and compared to the behavior of a single pile. The possible factors that influence the group behavior could be visualized. The experimental data was also compared to the widely used theoretical approaches to determine their adequacy. The analytical model makes use of the finite difference approach to calculate the soil non-linearity. A new approach equates the measured ground deflection and maximum bending moments of each row at every load level with the analytical model of single pile. This is the Deflection-Moment Fitting (DMF). The most suitable non-linear soil modulus modes and row contributions could thus be determined. Design of pile groups can be based on data pertaining to soil characteristics of the single pile. Results of the analysis were consistent with other approaches and proved to be adequate for design.

Jan 1, 2005

By Scott Webster

Dynamic pile Monitoring Services (DMS) have been used for testing of offshore piles for several decades. However, most of this testing was to measure hammer performance and pile stresses rather than pile capacity or soil resistance. As the need for more economical solutions for foundation support increases, the use of DMS has provided a better means of evaluating in-place pile capacity for offshore structures, and therefore a method of determining pile acceptance. The authors have been involved in several offshore projects where DMS has been the primary source of data for acceptance of the driven pile foundations. The use of DMS for evaluation of offshore foundations requires considerations quite different from land applications and these considerations are often necessary for the careful and thorough analysis of the collected data in nearly real time for determination of pile acceptance. Case Method capacity estimates are often of little use due to the non-uniform cross sections of the foundation piles and their deep penetrations. Therefore, capacity assessments should be made using CAPWAP which is a signal matching program whose utility and reliability has been proven on thousands of projects every year, both on land and offshore. Depending upon the soil conditions at a given location, capacity assessment after soil setup effects may be necessary. In addition, tension capacity is often critical when pile refusal occurs significantly before the design pile penetration depth. Evaluation of uplift capacity can be accomplished by a CAPWAP analysis, which results in a total capacity prediction and its shaft resistance component. The use of hydraulic hammers for driving of these piles also adds the requirement of controlling hammer energy such that over-stressing of the pile is avoided. The calculation of non-axial stresses such as bending or eccentric stresses may also be involved in order to prevent pile damage.

Jan 1, 2010

By Sastry Putcha, Santosh Mummaneni, Swamy Avasarala, Vamshi Vemula

"This paper presents the results from a case study on the comparison of two strain acquisition instrumentation technologies, Geokon rebar strainmeters and Embedded Data Collectors (EDC) for the DC Water Main Pump Station project, in Washington D.C. These two instrumentation systems were installed by AVER in a single 18-inch (0.45 m) diameter augercast pile (with one-1.25 inch (3.175 cm) dywidag bar) at critical locations to determine the load transfer mechanism and establish a comparison between strain/load measured with these two systems along the pile. A quick static load test was performed on the test pile as per ASTM D1143 standard.Prior to the installation of the pile, a 24-inch (0.6 m) diameter outer casing was installed to the proposed cutoff elevation of -22.5 feet (-6.85 m) to discount the frictional resitance within the upper overburden zone. The pile was then drilled through the outer casing to the tip elevation of -65.02 feet (-19.8 m) with inner casing within the overburden zone. Strainmeters along with EDC were installed on dywidag bar at various locations and then wet set into the concrete following auger retrieval. The loads measured with EDC and Geokon sensors were within 15% percent of each other.PROJECT BACKGROUNDProject Background & Requirements:Like any other foundation piles, augercast piles are extensively used in the public and private sector structures in the United States for many years. It is a common practice to perform static compression (ASTM D1143), tension (ASTM D3689), and lateral load tests (ASTM D3966) depending on the project requirements. In recent years, embedded strain sensors, manufactured by Smart Structures, USA has gained prominence for its use to collect both static and dynamic measurements for driven piles. In addition, AVER has successfully used EDC for collecting long term static measurements for an abutment drilled shafts for I-95 Hotlanes project in Virginia, USA.Geokon sisterbar strain gages are widely used in the foundation industry to monitor the load transfer mechanism within pile foundations throughout the world. As the Geokon strainmeters are vibrating wire and are welded to a sister bar, there is often a debate within the engineering community with regards to what modulus to use when converting measured strains to loads. EDC sensors, unlike Geokon strain gages are embedded directly into the concrete and therefore do not have the same concern."

Jan 1, 1900

"1 INTRODUCTIONThe use of nondestructive testing (NDT) methods to evaluate the integrity of Augered Cast-in-Place (ACIP) and Drilled Displacement (DD) piles has been a subject of significant debate among engineers, contractors and NDT practitioners. This guideline document will illustrate the importance of reviewing all available information in conjunction with the NDT records. ACIP and DD piles have unique properties that must be considered when using a specific NDT method. Any evaluation of the integrity of an ACIP or DD pile must also include a thorough review of the detailed pile installation records and the site specific soil conditions. Long or theoretical descriptions of the methods have not been included in this publication. More detailed information about these NDT methods including their theoretical and historical backgrounds can be found in DFI’s Manual for Non Destructive Testing and Evaluation of Drilled Shafts (2004). Additional information can also be found in the more comprehensive textbook Nondestructive Testing of Deep Foundations by Hertlein and Davis (2006).1.1 PurposeThe intent of this guideline is to provide practical guidance for the proper interpretation of NDT results on ACIP and DD piles. Short descriptions of the main integrity methods available are provided along with several examples of how to use all of the information available to make sound engineering judgments about the results. This publication is a state-of-the-practice guideline to promote accurate engineering evaluations.For engineers inexperienced with NDT, these guidelines provide sufficient background information on NDT methods to help understand the limitations of the testing, assess the results presented to them, and formulate appropriate questions. This is particularly important for engineers charged with the responsibility to determine from those results what, if any, consequences there may be on the performance of the structure under construction."

Jan 1, 2016

By Lorie M. Dilley

Alaska Village Electric Cooperative (AVEC), an electric utility cooperative providing power to 51 Alaska villages, has made a concerted effort to install wind turbines in the villages they serve in an effort to mitigate the growing costs of electrical power generation. The subsurface soils in several of these villages consist of sands and silts with ground temperatures of between 30°F and 32°F. The presence of warm, degrading permafrost in three of the villages has required innovative foundation designs, including the use of helical piers and piles to support steel and concrete wind turbine foundations. The design of the deep foundations had to account for the effects of degrading permafrost likely resulting from observed climate change patterns. Uplift forces imposed on the foundations were approximately 100 kips per pile. Uplift pile load testing was conducted on the installed piers and piles in order to determine the actual working load that each pier or pile could sustain. In addition, pile driving analyzer testing was conducted on several piles installed in the permafrost and compared to pile load tests. Results indicated that the installed piers and piles achieved the necessary capacity with sufficient factors of safety. Thermosyphons were installed near the foundations in order to limit the effects of climate change on the permafrost. The two to four wind turbines in each of the three villages are currently operational. Refinement of the design based on the pile testing from the first village to the third has decreased the cost of the tower foundations and improved our understanding of designing for warm, degrading permafrost.

Jan 1, 2010

By Giulia M. B., Ferruccio Cribari, Alessandro Bertero, Eliano Romani, Roberto Sorge, Francesca Casini

"The use of Artificial Ground Freezing (AGF) to form earth support and seepage control barrier systems has had applications worldwide. These cover a variety of construction problems, including the formation of frozen earth walls to support deep excavations, structural underpinning for foundation improvement, and temporary control of ground water in construction processes. An application of AGF during construction of Line C of Rome underground is described in detail.The new line “C” of San Giovanni metro station was constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and runs below the existing station. The underpass project envisages an Artificial Ground Freezing in order to create a structural and waterproof temporary cut-off suitable to the two new tunnels excavation, while keeping trains running in the safest possible condition. The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).Artifical Ground Freezing IntroductionNatural freezing occurs seasonally in many areas of the globe and can affect negatively the engineering performance of geotechnical structures; on the other hand, man-made freezing is a controllable process that can be used by civil engineers to stabilise temporarily the ground in order to support and/or exclude groundwater from an excavation until the final retaining and lining structures are constructed. Freezing and thawing of the pore fluid within soils involve complex thermal, hydraulic and mechanical processes that have significant mutual interactions. For example, phase changes of the pore fluid caused by temperature variations can modify the pore water pressure in the soil, which, in turn, can induce mechanical deformation. At the same time, any changes in the hydraulic and mechanical conditions affect the thermal processes by advection and changes of ice and water contents.An application of AGF which will be presented in the paper, refers to the construction works of Line C of Rome underground. In this case AGF was carried out to provide temporary support during excavation of the two Line C running tunnels directly underneath the existing S. Giovanni station of Line A, in the safest possible condition. In order to keep the trains of Line A operational during excavation, a temporary structure was installed and a real-time monitoring system was conceived in order to control the temperatures of the soil during freezing and the response of the structures of the existing station."

Jan 1, 2016

By Matthew Janes

The RC Harris Filtration Plant, which treats the majority of the fresh water for over 2.5 million Torontonians, is a Canadian Architectural Heritage site demonstrating a classic example of Art Deco Architecture. The facility is undergoing an expansion to install an underground sludge treatment capability. Perched atop a bluff on the North shore of Lake Ontario the structure enjoys a commanding presence on the Lake Ontario shoreline. A series of underground tanks were proposed for the hillside below the structure, which when covered would preserve the building?s architectural presence. However, the plan required two, stepped excavations 12 m and 10m deep into compact, wet sands over stiff clays and clayey silts. Concerns regarding the original structure influenced designers to set the lateral deflection limit for the front footing of the existing structure at 4 mm, (0.03% excavation depth). The design-build team indicated at the time of tender that the movement criteria was unattainable using the tender design. Analysis indicated installation effects and overall elastic movement of the soil mass beneath the building would result in movements of 7 to 9 mm at the structure. Through extensive FLAC analysis and a novel construction geometry the design-build team crafted an alternative that produced significant savings over the original concept. Based upon the analysis the design-build team negotiated a new deflection criteria dictating a maximum of 2.0 mm of movement across the critical expansion joint between the Filter Building front footing and the tank slab beyond. The contractor invested in additional pre tender soils investigation to support the refined design process. The FLAC analyses indicated the Filter Building movements would be elastic and distributed up to 50 m back beneath the front footing of the structure. An extensive precision monitoring program proved construction related movements of 6 to 10 mm horizontal at the front footing. Extensometers placed at two locations over the critical interior tank expansion joint showed no measurable movements. The overall monitoring program, including inclinometers, tilt meters, tie back extensometers (smart cables) and tie back load cells indicated a good match between recorded movements and loads and those predicted by FLAC Analysis.

Jan 1, 2006

By Max Gwynn, Tony Suckling

"The new Wembley Stadium is the most spectacular soccer stadium in the world, built to the highest specifications, using the latest technology and offering visitors an unrivalled match-day experience. Wembley Stadium is the home of English soccer, dating back to 1918 when the British Government began planning a British Empire Exhibition with a stadium as its centrepiece. The Empire Stadium, as it was originally known, was completed in 1924 in just 300 days and cost £750,000 ($1.4m). It was finally closed in 2000.The new Wembley Stadium, which opened in 2006, features fully covered seats for 90,000 fans and a striking arch that sits above the northern half of the stadium. With a span of 315 m (1040 ft), the 133-m (440-ft) tall arch is the longest single-span roof structure in the world. It supports the entire weight of the northern roof and 60% of the weight of the southern retractable roof. This means there is no need for columns within the stadium and ensures unobstructed views.Multiplex Constructions (UK) Ltd. employed Stent Foundations Limited to construct the £10m ($19m) foundations package for the new stadium. The scope of works for the foundation package included the design and construction of all foundations, including all main works piling, temporary works piles for the arch and roof, and tower crane piles. The scope also included trial piling and pile testing, setting out and removal of spoil.Piles were constructed by using bored cast-in-place techniques with both hydraulic and traditional crane-mounted rigs. Stent also installed sheet-piled walls at three locations to the site’s northern boundary. In addition to the main contract works, Stent constructed a £2m ($3.8m) contiguous bored-pile retaining wall within the demolition and earthworks package (Figure 1). This work was carried out as a subcontractor to Griffith McGee."

Jan 1, 2008

By Aly Mohammad, Dongyi Yue

"The design of rock sockets for drilled shafts and piles proves to be a challenge for the Design Engineer. The magnitude of loads on the shaft and the behavior of the rock are critical in determining the required socket length. Several acceptable methods are available in the literature to analyze a rock socket under a combination of axial loads, lateral loads and moments. This paper will present a state-of-the-art methodology to analyze rock sockets utilizing deformation characteristics of the rock. This design methodology was implemented in the design of a major project in New York City.The project discussed herein is a marine transfer station planned for construction at East 91st Street along the East River in Manhattan. In order to support the piers and platform structures at a site with relatively shallow depth of the bedrock, rock sockets were required for the drilled shaft foundations. Rock sockets were utilized to provide the required fixity to the foundations and the structures. Acting at the top of the rock sockets are large shear forces and moments created by the lateral loads transferred from the structure.Upon review of the available techniques, a simplified method was proposed and used to analyze the rock sockets with a significant magnitude of lateral loading. The method recognizes two mechanisms through which the lateral shear and moment are transferred to the rock; a) load transfer through horizontal resistance of rock and b) the vertical shear resistance of the bond between socket and rock.The first load transfer mechanism was analyzed using the p-y curve method based on a rock model developed by Reese. The second was analyzed using a bond stiffness derived from the formula and curves utilized in the AASHTO Specifications for calculation of rock socket displacement. By comparing the two mechanisms, the main contribution to the large horizontal shear force that developed in the rock socket is identified.The paper will present a summary of the design methodology utilized in determining the length of the rock socket. It is believed that the presented method will provide substantial cost saving in selecting the most economical and efficient design length."

Jan 1, 2005

By Jianhua Wang, Jianming Yao, Zhen Meng, Jinjian Chen

"Drilled screw pile is a newly developed displacement pile foundation which has been applied in soft clay for many years. Compared with traditional circular displacement pile, It is characterized by high bearing capacity, small volume and small squeezing effects. For the purpose of investigating the squeezing effects of drilled screw pile, a full scale field monitoring test with two test piles was performed. Detailed soil horizontal displacement and pore pressure measurements were conducted in the vicinity of the two drilled screw piles during penetration and subsequent soil consolidation. It can be concluded that the horizontal displacement of the surrounding soil induced by the installation of a drilled screw pile is mainly in a circular region with a diameter of 3 m (r/D<6), and the compaction effect outside the area can be essentially negligible; The excess pore pressures measured at the same time increase with depth throughout the entire process of consolidation, and its dissipation shows an exponential decay as a function of time.INTRODUCTIONA knowledge of the displacement and stress changes induced in the soil surrounding a pile is very important for evaluating pile performance. Numerous field and laboratory research projects have examined loading conditions, total soil stresses, and excess pore pressures during and following pile installation (Pestana et al., 2002). A relatively comprehensive and detailed review of these experimental works from 1948 to 2002 was presented by Pestana et al. (2002). More recently, Xu et al. (2006) conducted a field experiment to study displacements and stresses in the vicinity of two pipe piles during their installation in a soft lightly overconsolidated clay and compared the field measurements with existing predictive methods. Abdrabbo and Gaaver (2011) collected field observation data from four different construction sites to study soil disturbance during construction of piles using continuous flight auger (CFA). They have found that the disturbed zone of soil by CFA has a conical shape and the excess pore pressure has no appreciable influence on the load capacity of the piles.Drilled screw pile (DS pile) is a kind of vibration-free, cast-in-place concrete pile. Because of the excellent bearing performance, low level of vibration pollution and negligible spoil, as well as its fast construction speed, DS pile has been widely accepted by many engineers around the world. As a new type of drilled displacement pile, the significant installation effects of DS pile on the adjacent soil have not been systematically and integrally investigated yet. Since a proper numerical simulation of the real installation process of DS pile is difficult to achieve, the investigation based on field measurements is necessary. This paper presents a field investigation of the installation effects of two DS piles on surrounding soils. Detailed horizontal soil displacement and pore pressure measurements during pile installation and subsequent soil consolidation have been conducted. Based on the monitoring data, variation of horizontal displacements and dissipation of excess pore pressures with depth and time have been analyzed. What's more, the construction machinery and technology used in DS pile installation are also simply introduced."

Jan 1, 2015

By Matthew E. Meyer

Renovation, rehabilitation, restoration and expansion of existing residential, retail, commercial, hospital facilities and historic structures requires assessment and evaluation of foundation systems of various ages. The concept of demolition and reconstruction in urban areas is often more challenging, costly, and even prohibitive in some cases due to historic regulations. The authors have been involved with numerous projects related to existing foundation assessment and retrofit, including: hotel and hospital expansions, historic Art-Deco hotel renovations and expansions, garage structure expansions, additions to prominent auction houses, casinos, printing facilities; high-rise structure foundation retrofitting; and forensic evaluations of existing building and highway structure foundation systems, and marine bulkhead sheeting systems. The use of non-destructive testing techniques, high-strain dynamic load testing, full scale pile cap load testing and 3-D laser scanning technology has proved to be vital in the assessment and evaluation process, as well as design of foundation retrofit alternatives. This paper presents various methods and techniques to facilitate a phased approach for re-use of foundation systems. These methods and techniques are illustrated through the author?s experience and selected case histories from projects with varied foundation and geologic conditions.

Jan 1, 2009

By James M. Tantalla, Jr. Ellman

"Construction of the powerhouse for the Willow Island Hydroelectric Project, located at the Willow Island Lock and Dam, required a 120-ft deep temporary excavation inside the limits of a cellular cofferdam on the Ohio River side of the excavation and a soil-bentonite seepage cut-off wall on the landward side of the excavation. Stability analyses were performed for critical sections to evaluate the stability of the soil slopes and rock cuts using limit equilibrium, tension crack, and buckling analysis techniques. The stability analyses indicated adequate factors of safety through the landside embankment sections, and for the weighting berm soil slopes in front of the riverside cellular cofferdam. However, the results of deep-seated stability analyses through the rock supporting the riverside cellular cofferdam indicated marginal factors of safety for the 100-year flood condition. Consequently, the riverside portion of the excavation required enhanced stability measures, namely the installation of long, high-capacity rock anchors. Also, the dewatering system was modified to lower the site piezometric head to near the top of rock to improve the stability of the rock cuts.Thirty high-capacity rock anchors were installed on the upstream, riverside, and downstream sides of the cofferdam rock cut. The rock anchors consisted of multiple, seven-wire strands designed to provide the full-required design load at 60% of the strand capacity. Rock anchor loads varied from 1,968 to 2,074 kips. The maximum number of strands per anchor was 59. Bond lengths assumed an allowable bond stress of 100 psi based on the rock bond from pull-out tests.Project DescriptionAmerican Municipal Power, a nonprofit organization that owns and operates electric generation facilities for its member communities, has been in the process of constructing hydroelectric power plants adjacent to existing navigation locks and dams along the Ohio River. The Willow Island Hydroelectric Plant was recently completed on the West Virginia bank of the river adjacent to the US Army Corp of Engineers (USACE) Willow Island Lock and Dam. The plant is on the opposite river bank to the locks, and includes two turbine generating units with FERC rated capacity of 44MW at a 20-foot head differential. The Ruhlin Company of Sharon Center, Ohio was awarded contracts to construct both the cofferdam and the powerhouse. Construction began in mid-2011, and was completed in early 2016."

Jan 1, 2016

By Jochen Maurer, Dr. Christian Hoyme, Dr. Hans Regler

Currently, it is very difficult to obtain qualitative and quantitative information about the status and production process of a construction site. As a rule, companies depend on reports from on-site experts. There is no end-to-end digitalization due to the mobility of equipment and ever-changing locations. Equipment from different manufacturers, especially in special foundation engineering, is highly specialized. Any data collected by this equipment is recorded in proprietary formats and made available on the manufacturers' platforms. This exacerbates the situation, making simple analysis of performance indicators impossible. Most functions such as construction diaries, equipment utilization analyses, etc. are implemented only as standalone solutions. This does not allow for prompt visualization and intervention in critical process sequences because the construction site process is usually managed using a cost-based method. Furthermore, special foundation engineering requires a high level of expertise in an extremely wide range of construction processes. In this article, the results from a set of non-proprietary performance analysis tools are presented using numerous practical examples. Once a construction element is completed, the equipment data is immediately transferred to the platform using the latest cloud technology. Because the data is normalized, construction progress can be documented immediately, even for mixed equipment fleets. Bottlenecks can be immediately detected by visualizing the current performance of the production process, which is broken down into individual steps. Modern analyses of this equipment data improve quality, thereby providing better information about current performance. These sets of tools are essential for changing from the current monetary or cost-based method of process management to time- and bottleneck-oriented management. This makes it much easier to identify the critical path during projects. The article shows that processes can be documented and managed.

By Frédéric Rocher-Lacoste

On July 2nd, 2007, LCPC and LOADTEST performed a static loading test with an Osterberg-cell on a bored pile of 1600 mm diameter. The 56.50 meters deep test pile constructed by Trevi Spa for Soares da Costa group, was near the Cacheu river in Guinea Bissau. This test was conducted to validate the design of the foundations of the Sao Vicente bridge; a project undertaken by the Ministry of Public Works of the Republic of Guinea Bissau and funded by the European Development Fund. Sub-surface conditions at the test pile location consist primarily of layers of weak sands and clays. The piles were loaded statically using the O-cell® bi-directional method 25 days after concreting. The maximum sustained bi-directional load applied to the pile was 11.7 MN. At the maximum load, the displacements above and below the O-cell assembly were 6.6 mm and 81.9 mm, respectively. The resulting pile head behavior has been calculated for a combined skin friction and end-bearing load of 29.3 MN. The piles were also instrumented using LCPC removable extensometers, which made it possible to measure the mobilization of shaft friction and toe resistance. The adjusted test data indicated that this pile would settle approximately 12.2 mm for the service load of 12MN applied at the head of the pile. This paper provides a very brief presentation of the bridge project and the test pile instrumentation: LCPC removable extensometers and O-cell® instrumentation. The results are detailed and analyzed herein and the combined use of these two instrumentation systems is a world première.

Jan 1, 2008

By Rae Mackay, Kaveh Ranjbar Pouya, Ali Tolooiyan

"A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Due to the low strength of CIS, most construction in the region is based on pile foundation systems. Traditionally, the design of pile foundations is mostly based on empirical and analytical methods. However, numerical methods such as Finite Element Methods (FEM) can be utilised for more accurate estimation of the bearing capacity and deformation of pile foundation systems, especially in complex loading scenarios. Unfortunately, no systematic effort is made yet to calibrate a realistic nonlinear constitutive model to describe the geomechanical behaviour of CIS in a numerically based solution. Among the nonlinear constitutive models, the Hardening Soil (HS) model is an advanced hyperbolic model which accounts for the nonlinearity of stress-strain relationship as well as the stress dependency of the soil stiffness. In this study, the HS model is calibrated based on laboratory tests performed on CIS. Also, to validate the accuracy of the calibration, the wellknown cavity expansion theory is employed to model the CPT cone tip resistance (qc) in CIS, and results are compared against the measured CPT qc profile at the field.INTRODUCTIONA large percentage of world’s coastal areas are covered with soft marine clay deposits. Having very low shear strength and high compressibility, the alluvial deposits are known as one of the most problematic soil layers for the design and construction of infrastructure facilities. A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Basically, there are two main solutions for construction in such weak soil conditions. One is the use of pile foundations transferring the applied load to deeper and stronger soil layers, and the second one is to employ ground improvement techniques such as using deep soil mixing columns to improve the bearing capacity of the soil. In both cases, a practical geotechnical design should incorporate both stability analysis and deformation analysis to achieve a cost-effective and reliable solution. Most of the classic solutions for stability analyses such as limit equilibrium analysis disregard the stress-strain relationship of the soil for the sake of the simplicity (Chen, 2007; Sokoloviskii, 1965). In a similar simple approach, most of the past studies of deformation analysis have been established on the basis of linear elasticity. However, it is well recognised that the soil stress-strain behaviour is highly nonlinear even at very small strains (Burland, 1989). Hence, for a precise deformation analysis of the foundation of important geotechnical structures, the application of advanced nonlinear constitutive models is extremely beneficial. Precise deformation analysis is essential as geotechnical designers have to predict the displacement of geotechnical structure and the adjacent soil as well as the induced displacement and forces to adjacent structures. This issue is more highlighted recently in the analysis, and design of highly important infrastructures as geotechnical engineers are facing new challenges in the analysis and design of infrastructures in congested areas. Rapid population growth, especially in the major cities all around the world necessitates the design and construction of more integrated infrastructure facilities. Consequently, geotechnical engineers should employ more advanced design approaches to address the new challenges in geotechnical engineering practice. Complicated geometries, different loading scenarios and the application of nonlinear deformation models which is believed to be essential for a precise deformation analysis, necessitate the application of numerical methods to satisfy most of the design requirements."

Jan 1, 1900

By S. R. Nandargikar

Construction of open foundations for the Second Thane Creek Bridge was indeed a challenging task. Some major problems were encountered during the construction of foundations for pier No. P22 (S/N), P.6(S) and P.12(S) of this bridge. This paper describes these problems briefly and also highlights how they were solved.

Jan 1, 1996

By Adrian Gygax, Sarah Gaib, Rod Kostaschuk

The British Columbia Ministry of Transportation and Infrastructure (Ministry) recently completed a slope stabilization project at Ten Mile Slide on Highway 99. The highway is an essential part of the road network connecting the British Columbia (BC) coast with the interior of the province. The landslide was first identified in the mid-1980s and has retrogressed more than 250 m upslope since then, leading to continual and expensive repairs to the highway. The Ministry engaged BGC Engineering Ltd. (BGC) and their structural sub-consultant Gygax Engineering Associates Ltd. (GEA) to develop a stabilization scheme that would halt the slide with an acceptable level of residual risk. The design required careful consideration of construction stages and the stresses induced in the structural components as the slide movement was progressively stopped as construction advanced. Four stabilization design options were shortlisted with the preferred option selected in Fall 2016. The selected solution comprised the construction of five rows of post-tensioned soil anchors upslope of the highway and a tied-back concrete tangent pile retaining wall for the roadway itself as well as reconstruction of the highway alignment, grade and drainage through the slide. Works were installed by top-down construction within defined time allowances stipulated in the contract. Significant engineering was undertaken beyond standard design processes for this complex project, such as comprehensive geotechnical investigations, aerial and terrestrial laser scanning and change detection analyses, pre-production test anchors, detailed geo-structural numerical modelling and due diligence activities to validate and optimize the design. The stabilization works have been very successful with the slide response being as predicted and the highway operating again as full two-lane service.

Oct 1, 2022

By Alice Arana, David M. Cacoilo, Joel L. Volterra

"To make space for the new South Ferry Station in lower Manhattan, engineers and contractors carved out a new tunnel beneath three operating subway tunnels and tangentially to yet another tunnel. Creating the space required the design and construction of complex temporary excavation support and underpinning systems and the design and installation of real-time monitoring systems. Construction for the new station and tunnel was mainly cut-and cover in a mixed-face area of soil and rock approximately 2,000 linear ft long, 60 ft wide and up to 70 ft deep. Close coordination between the design/build team and the project owner, the Metropolitan Transportation Authority (MTA), was critical.With the construction of this $400 million project, the MTA and New York City Transit (NYCT) are correcting the numerous physical and operational deficiencies of the existing station and improving the lives of millions of commuters. Built in 1905, the original South Ferry Station is on the IRT Broadway–Seventh Avenue Line of the New York City Subway and is the southern terminal of the #1 subway service, which forms a loop to return uptown. The station has a sharply curved single platform on the outside of the outer track of a two track loop. This platform is short and does not allow the rear five cars of a normal 10-car subway train to load or unload. In addition, once the train stops at the station, commuters wait while retractable floor grates bridge the gap created between the platform and the subway car doors, and then they have only one exit from the station. Spray nozzles keep the tracks lubricated to reduce the train wheels’ friction caused by the tight curve. The sharp curvature of the loop and the inability to use half of the subway car doors slow train operation. With the new ADA-accessible station, 10-car trains will be able to open all doors, and additional entrances, escalators and elevators will greatly reduce travel times."

Jan 1, 2008

By Les R. Chernauskas

? What is Integrity Testing? ? Cross-Hole Sonic Logging (CSL) ? Single-Hole Sonic Logging (SSL) ? Typical Specifications ? Case Histories ? Observations and Conclusions WHAT IS INTEGRITY TESTING? General Definition ? Process in which the condition or structural makeup of an object can be evaluated with respect to defects such as a reduction in cross section (void or crack) or reduction in material strength (water, slurry, soil mixed with concrete). ? If the defect is severe enough, it can reduce or alter the load carrying ability of the object.

Jan 1, 2001