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By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan, Joseph Toth

The difficulty in material characterization and the erratic response of cemented soil layers, such as caliche in the Las Vegas valley, creates challenges for practicing engineers to reliably predict the response of deep foundations. The focus of this paper is the numerical prediction of axial response in drilled shaft foundations, which are commonly used in infrastructure projects (i.e., bridges and tall buildings) in Las Vegas, NV. The prevalence of hard caliche layers with variation in the degree of cementation add to the complication in numerical modeling. In this study, the applicability of two existing t-z models, developed for Florida limestone and soft rock, was evaluated based on numerical simulations of three bi-directional load tests conducted at caliche-dominant sites. The corresponding top-down load tests were also simulated for further assessment. A MATLAB-based finite-difference program, NVShaft, has been used to implement the mentioned t-z models in axial load analysis. Complexity originating from drilled shaft construction and the interaction with caliche during one axial load test resulted in a stiffer predicted response compared to measure data. For the other two load tests, both t-z models produced comparable load-displacement responses. It was observed that the t-z model for Florida limestone predicted relatively stiffer responses and higher drilled shaft capacity.

Sep 8, 2021

By Marco Fellin, Van E. Komurka

Significant cost and construction benefits were obtained from performing a bi-directional static load test prior to construction on the Russell Street Bridge Replacement project in Missoula, Montana. The project utilized 24 drilled shafts to support two three-span bridges across the Clark Fork River. A bi-directional static load test (“BDSLT”) was performed on a large-diameter production shaft to demonstrate construction methods and confirm design assumptions. Subsurface conditions consisted of gravel with sand to a depth of 20 feet (6.1 m), underlain by gravel with sand, silt, cobbles, and occasional boulders. The test shaft had a nominal diameter of 5.9 feet (1.8 m), and an embedded length of 75.5 feet (23.0 m). The geotechnical engineer of record and the BDSLT test engineer collaborated to optimize the BDSLT jack assembly location within the test shaft, determine appropriate instrumentation locations, and plan the test protocol. The maximum applied test load was 10,707 kips (47.6 kN). Significant benefits were obtained from performing the BDSLT test, including 1) reducing each production shaft’s length by using a higher LRFD resistance factor allowed by having performed the testing, 2) using test-determined unit shaft resistances to evaluate and accept two production shafts that may have otherwise required remediation, and 3) providing the Montana Department of Transportation (and other designers) with increased presumptive unit resistance values in the gravel/cobble/boulder deposits. PROJECT DESCRIPTION The project was constructed in Missoula, Montana for the Montana Department of Transportation (“MDT”). The original bridge was approximately 60 years old, and consisted of a two-lane, 420-foot-long (128-m), four-span, riveted steel plate girder design spanning the Clark Fork River. The bridge was due for replacement owing to its deteriorated state, and the need for increased traffic volume capability afforded by a four-lane structure. HDR was the structural engineer. The preferred bridge alternate was a 459-foot- long (140-m), three-span, welded steel plate girder design. The new bridge was designed to meet current standards in accordance with MDT bridge design and AASHTO LRFD criteria. The new bridge was constructed in phases to keep traffic open during construction.

Jan 1, 2019

By Leena Korkiala-Tanttu, Noora Lindroos, Juha Forsman

"Construction works at the Helsinki city sea shoreline requires dredging and handling of contaminated sediments. Most of these soft dredged sediments are regarded as too poor quality material for earth construction purposes. Mass stabilization technology has been applied to improve the technical and environmental properties of the dredged sediment in order to utilize the material in construction. The treatment site presented in this article is placed in the West Harbor where the dredged sediments are disposed in basins, mixed with binders by mass stabilization and transported to utilization sites. The volume of these basins is about 90 000 m3. So far these basins have been used three times during the years 2011-2014. The most applied binder has been cement. Its high price and carbon footprint have encouraged use alternative binders. Other used binder materials include fly ash and end product of desulphurization from coal combustion, and fly ash from combustion of Estonian oil shale. The technical and environmental properties of stabilized sediments have been studies in the laboratory and in situ thoroughly. Some properties of the stabilized sediments which have been studied are: compression strength, modulus, hydraulic conductivity, leaching of contaminants, etc. The leaching test results show that heavy metal leaching is very low with all binder materials tested.1. INTRODUCTIONContaminated marine sedimentsMarine sediments in the coastal areas are often contaminated as a consequence of industrial and port activities, as well as the influence of cities located there. Construction activities and reclamation of shore line require dredging and handling of contaminated sediments since the level of contamination inhibit dumping of dredged sediments into the sea. Based on their technical properties, most of these dredged soft and watery sediments (clay, gyttja, etc.) are regarded as too poor quality material for earth construction purposes. Economic, sustainable and environmentally safe management of contaminated, dredged sediments is a key issue in many construction sites.In the City of Helsinki, mass stabilization technology has been applied to improve the technical properties of the dredged sediments in order to utilize the material in construction. Owing to stabilization / deep mixing / solidification, also the contamination is encapsulated in a monolithic solid of a high structural integrity. Thus, contaminants migration is restricted by the decreased surface area exposed to leaching.The treatment site presented in this article is placed in the West Harbor (a place of Helsinki called Jätkäsaari) where dredged sediments are disposed into stabilization basins, mixed with binders by mass stabilization and then transported to final utilization sites. The location and principle of these basins is presented in Figures 1-4. The overall volume of these four stabilization basins is about 90 000 m3."

Jan 1, 2015

By Karl A. Higgins

In August 2004, the long-awaited National Harbor project in the DC metro area sprang to life with the design of Gaylord National Resort and Convention Center. When the project was in its final stages of construction in 2007, it was noted as largest building development of the east Coast and the 4th largest Building project in the U.S. The final construction costs were above $900M and it served as the catalyst for the overall National Harbor development which added another $1B in construction costs over the next few years. The Gaylord Hotel is supported by approximately 150,000 linear-feet of driven precast concrete piling, one of a handful of major DC area projects in the early 2000s that were supported by this pile type. The project overall was a success, but the fast-paced construction schedule created significant challenges to the designers and contractors. Piling installation was the first major building construction task, and it did not start out well. While the test piles were installed without damage, when production pile driving began in the summer of 2005, pile head and body breakage soon became evident. Typical of most highprofile projects, there are many stakeholders involved and an equal number of opinions on why the piles were breaking. The financial and contractual implications of starting the project off awkwardly were evident to all. The pile driving criteria was scrutinized by the contractor, and the engineer’s had reservations about the size and type of the hammers used for pile driving. Ultimately, it was proven the leading cause of pile breakage was neither the pile driving criteria nor equipment, rather the pile materials themselves. The author of this paper is also the Geotechnical Engineer of Record for Gaylord National and many of the adjacent National Harbor buildings including the recently completed MGM casino. About 100 piles were damaged during Gaylord’s construction some requiring multiple piles for replacements. Over the past decade or so, rumors on the causes of the pile breakage have spread in the market, with some alleging this pile type is not compatible with the geologic setting. I have purposely avoided writing this case-study due to the controversy surrounding the subject, but now some 15 years later it seems appropriate to do so considering DFI’s annual conference location. This will be a fact-based assessment of pile breakage at Gaylord and will also include a comparison to the neighboring buildings where far fewer driven piles were damaged, once a more appropriate concrete mix design was required. The pre-cast supplier is no longer in business.

By Mario Mauro

Tuttle Creek Dam was constructed by the U.S. Army Corps of Engineers in the 1950?s on the Big Blue River in north-east Kansas. Since the dam is located in a seismic area, the safety of the dam was re-evaluated under the national U.S. Army Corps of Engineers Dam Safety and Assurance Program. After a series of studies and analyses performed by the Kansas City District of the U.S. Army Corps of Engineers, in 2003 the Department of the Army authorized the implementation of the plan ?Stabilize Foundation Soil without Drawdown Alternative?, during a 7-10 year construction period. As part of this plan, in 2006 Treviicos South carried out a large scale jet grouting and deep mixing test program downstream the dam. The test program included the installation of twenty-seven double and triple-fluid jet grout columns and twenty-seven jet-assisted deep mix columns. The jet grout columns were constructed at different levels of specific energy and cement content. The deep mix columns ranged in diameter between 3 ft and 6 ft. During column placement, the drilling and grouting parameters, pore pressures, and soil movements were instrumented in real-time. The downstream test area was enclosed by a cement-bentonite wall extended to bedrock, which allowed a 35-ft deep open excavation around the 45-ft deep columns. The exposed jet grout columns measured up to 15 ft in diameter, exceeding the anticipated target diameter. In addition to coring, some of the jet grout and soil mix test columns were saw-cut along the group axis, providing useful information on the internal column structure.

Jan 1, 2008

By Mahesh Hingorani

Integrity issues for bored cast-in-situ piles have raised the need for the use of non-destructive tests to verify pile integrity and detect possible anomalies in installed pile sections that could adversely affect their serviceability. Integrity inspections performed after installations are often the most reasonable alternative available to assess the shaft quality. The two most common methods are pulse-echo from a small hand held hammer at the pile top, and cross-hole ultrasonic transmissions along the shaft between parallel sonic pipes. While different in technique, each method has its advantages and limitations. This paper emphasizes more on the degree of accuracy of low-strain pile integrity test by comparing the results with cross-hole sonic logging. Reliable data collection and interpretation by an experienced test engineer will reveal the integrity of the pile. Cross-hole sonic logging and low-strain pile integrity testing were both specified as quality control measures for a metro rail project in India. Both cross-hole sonic logging and low-strain pile integrity testing indicated defects in several bored piles. Also minor imperfections recorded by cross-hole sonic logging were observed in low-strain results. The observations of the two test methods are presented and compared for a better understanding of the importance of low-strain test results for any project. INTRODUCTION Cast-in-situ concrete piles are often chosen as a deep foundation alternative where challenging soil conditions exist. Although quality control measures are almost always taken during the installation of the piles, it is often difficult or impossible to confirm the integrity of the pile at this stage, particularly in wet conditions. Because of the relatively high probability of bored piles having anomalies, quality assurance of each bored pile is essential for each project.

Jan 1, 2019

By Nadir Ansari, Brian W. Wilson, Marina S. W. Li

"A hybrid shoring system consisting of cast-in-place soldier piles with Cutter Soil Mixing (CSM) infill panels was constructed for temporary support of a 19.8 m (65 ft) deep excavation in Vancouver, British Columbia, Canada. Deep Mixing (DM) was completed up to 9.7 m (32 ft) in fill, peat, wood waste and clayey silt with embedment in dense till, and soldier piles constructed through the dense till extending to below final excavation level. Two trial CSM panels were installed ahead of production to assist with developing the termination criteria of the CSM panels in the dense till. The constructed depth of the CSM panels was based on interpretation of real-time monitoring data obtained through the Bauer B-tronic system. Inclinometer monitoring data from two CSM panels and two soldier piles, as well as soldier pile survey target data was used to assess and monitor the performance of the hybrid shoring system throughout bulk excavation. The objectives of this paper are to provide an overview of the design and construction aspects of the hybrid DM shoring system and to present inclinometer and pile target data to demonstrate the lateral performance of the CSM infill panels and soldier piles. This paper also discusses the merits of using real-time monitoring data as part of the engineering decision-making process for validating CSM panel construction. BACKGROUND A hybrid DM shoring design was recently completed for a high-rise development in downtown Vancouver, British Columbia for temporary support of a five level basement excavation. Deep mixing was proposed by the excavation and shoring design-build team as the preferred method to construct infill panels between soldier piles because of the speed at which the shoring system could be constructed in variable fill, peat, wood waste and overburden compared with traditional secant piling methods. The development site is generally a truncated triangle in plan, with the longest side of the triangle being approximately 115.7 m (380 ft) long and the two shorter sides being approximately 71.6 m (235 ft) (Hybrid Shoring Wall 1) to 75.0 m (246 ft) (Hybrid Shoring Wall 2) long. The site is bounded by an existing bridge off-ramp structure along its longest side, and by city streets on the other two sides, as shown in Figure 1. The truncated section is approximately 16.8 m (55 ft) (Hybrid Shoring Wall 3) long. Due to project constraints, the hybrid DM and soldier pile shoring system was only proposed for the two shorter sides of the triangle and the truncated section. Traditional secant piles were installed for the longest side. This paper focusses on the hybrid shoring system. A typical detail showing the CSM infill panel with the soldier piles is presented in Figure 2."

Jan 1, 2017

By Reda Mikhail, M. Birkan Bayrak

The Washington State Department of Transportation (WSDOT) State Route (SR) 167/70th Avenue East Vicinity Bridge Replacement Design-Build project is located in Fife, Washington. This $40 million project consists of replacing the existing 70th Avenue Bridge over Interstate 5 (I-5) with a single-span bridge of about 220 feet long with approach embankments. The subsurface conditions along the new bridge alignment generally consists of alluvial deposits with high potential of liquefaction overlying glacially overridden deposits. In the early stages of the project, drilled shafts were considered as the deep foundation system; however, after an additional subsurface investigation is completed at the site, driven pipe piles were selected as the deep foundation system. Bridge abutments are supported by 24-inch diameter, 80-foot-long open-end driven steel pipe piles. The pile length was determined to bypass a relatively thick liquefiable zone and to tip the piles above what could be compressible soils. The use of advanced seismic analysis was instrumental in optimizing the pile length. The dynamic testing performed on numerous piles indicated what could be unique soil setup factors compared to those measured in local projects as well as those reported in national design manuals. Detailed discussions of the pile foundations design and construction is presented in this paper.

Sep 8, 2021

By Sowmiyaa. V. S., Tiruvengala Padma

Axial compression capacities of bored cast in situ piles as per Indian and International Standards are compared in this paper. Bored cast in-situ piles resting on soil and rock are considered for capacity assessment comparison. The standards considered for comparison are Indian Standards namely IS 2911-Part 1-Sec 2:2010 and IRC 78, International Standards like AASHTO LRFD Design-2017, API 2A WSD, BS 8004:2015 & EN 1997: Part 1:2014. The end bearing mobilization limits as proposed by various standards and their influence on longer piles in cohesive and cohesionless soils are discussed.

Sep 1, 2022

By Wu Jian-tao, LI Guo-wei

"The Cement Mixing Pile (CMP) quality assurance assessment is an important programme in evaluating the efficiency of foundation improvement. Coring is the current specified method of quality assessment in China which has the shortcomings of long cycle, high cost and low efficiency. The field and laboratory test show that the regular cone penetration test can only detect maximum of 4m of effective detection depth in CMP. In contrast, the method of cone penetration test in the reserved hole can detect the quality continuously along the pile at any depth. The tip resistance of reserved hole penetration in the 7th day has good linear relationship with unconfined compressive strength in the 28th day. The slope of linear relationship decreases with the increasing of clay particles content.INTRODUCTIONThe method of Cement Mixing Pile (CMP) is often used to improve soft soil foundation in highway construction, with the major purpose of reducing settlements under embankments (Bruce et al., 2000),which is a form of what is known as the Deep Mixing Method (Bruce et al., 2013). The CMP technology spread quickly in China in the 1980s. CMP quality assurance assessment is an important programme in evaluating the efficiency of foundation improvement. Coring is the current specified method of quality assessment in China (China Academy Of Building Research, 2002). The method of Coring is perceived in some quarters that samples will provide lower strengths given the distress caused to the core during drilling and extraction (Bruce et al., 2002).The cone penetration test CPT can provide continuous measurements of the penetration resistance, sleeve friction at the tip of the probe, which has advantages of simple operation, low cost and high efficiency compared with coring. However, CPT tests have not been established to assess CMP in Sweden because of difficulties in maintaining verticality (Larsson, 2005). In Finland and Norway, however, CPT tests are commonly used (Halkola, 1999). One of the disadvantages of CPT is the tendency of the cone to steer out of the column (Porbaha et al., 2003). Darya Mokrousova (2010) states this tendency to deviate can be overcome by pre-boring and starting the penetration test from the base of the pre-bored hole. Sheng Haiyang (1999) found that probes may be deflected out, sometimes even at small penetration depths, and may not give a complete inspection of the pile. Liu Songyu et al. (2003) suggested that the Standard Penetration Test (SPT) is an effective way to evaluate the strength and quality of stabilized soil-cement columns. In general, Regular CPT can’t test the full length of CMP, and SPT still needed drilling which causes discontinuous detection. From the existing standard of China, core sampling compressive strength test is the main method, evidently, coring displays a longer test cycle, high cost and low efficiency. Therefore, an improvement of CMP quality assessment, by conjuring a fast and reliable detection and evaluation method, is necessary. The aim of this paper is to research the feasibility of using CPT in assessing the quality of CMP and presents an improved CPT method."

Jan 1, 2015

By Adam Gerondale, David Hemstreet, Lisheng Shao, Kenji Yamasaki

"Foundation soils of a proposed single-span bridge over a busy railroad in Anchorage, Alaska included a layer of sensitive, non-plastic to low-plasticity silt. Slope stability analyses showed that, without ground improvement, the proposed abutments would not be stable immediately following the design earthquake due to the liquefaction of the sensitive silt. Wet soil mixing was selected to mitigate the liquefiable soils and assure abutment stability because: (i) it is a non-vibratory method and can be used for areas adjacent to the railroad tracks and underground utilities, as well as in areas not sensitive to vibration; and (ii) preand post-ground improvement testing, such as SPT or CPT, is not required. Eliminating the liquefaction hazard at the site also allowed for the abutments to be economically supported on shallow spread footings. A total of 511 soil-cement columns were constructed at the two abutments, each with a diameter of 8 feet (2.4 m) and an average length of 20 feet (6.1 m), extending from about 30 to 10 feet (9.1 to 3.0 m) below finished ground elevation. The columns were laid out in a shear wall pattern (in the longitudinal direction of the bridge) to increase stability under the loading by approach embankments.INTRODUCTIONAlaska Department of Transportation and Public Facilities (Alaska DOT&PF) is currently constructing West Dowling Road Overcrossing in Anchorage Alaska. It will be a single-span, steel box girder bridge approximately 200 feet (61 m) long and 100 feet (30 m) wide. It will have approach embankments, about 40 feet (12 m) high, on both sides. It will carry the new extension of West Dowling Road over double tracks of Alaska Railroad and Arctic Blvd. Foundation soils of the abutments consist of surficial fill and peat layer underlain by soft silt which is likely to liquefy and lose strength under shaking by a design earthquake. Both deep and shallow foundations were considered to support the bridge abutments. The design team pursued the option of improving the foundation soils and using shallow footings. Several ground improvement methods were evaluated, out of which wet soil mixing was selected as the best option.In situ wet soil mixing (hereinafter simply soil mixing) is mechanical mixing of soil in its location with cement slurry and produces soil-cement (soilcrete) columns that are stronger, less permeable, and less compressible than the original soil. Soil mixing is used for various applications including reinforcement of soft soils, excavation support, liquefaction mitigation, cutoff walls, etc. This paper presents a case history of soil mixing successfully used to improve foundation soils of bridge abutments to allow the use of spread footings."

Jan 1, 2015

By Nagarajkumar BV

Pavai-and TeampT JV started working on the project T49A, Sumbar J & K State as part of slope and earth stabilization for ongoing Banihal - Katra Railway Connection Project. This project has several tunnels and bridges with slopes that are protected with various types of protection system such rock bolting, rock anchors, and micro piles. For the main two bridges Bring number 2 and 3 at T49 A location Pavai - TeampT JV has to design and execute the circular group of micro piles (Fig.1) for deep excavation of earth for the purpose of construction of well foundations (CAISSON FOUNDATIONS) for both bridge 2 and 3 piers. In this paper we discuss about the purpose, basic design, detailed design approaches and actual work implementation of micro pile with composite rock bolt applications and permanent rock anchors for slope stabilization works in this project.

Nov 1, 2022

By Thomas Domanski

Any type of deep excavation whether for Bored Piling, Diaphragm Walls or Contiguous Bored Piling Walls depends on forming a stable borehole with a defined cross-section to receive safely the permanent materials. In modern construction the excavation depth can reach well the range of 100 m and above. The diameters of the Piles reach often sizes of 2.5 m and bigger. Top casings in Bored Piles (Diaphragm Wall none) are rather short and stability below the casing, need to be secured by stabilization slurry. The boreholes need to be formed through a variety of different materials and stand open for an extended period. Without a safe stable borehole, it is impossible to produce quality products and work cost-efficient. The understanding and proper usage of a suitable slurry is a key element essential for the delivery of Foundation Elements with high quality and within a reasonable budget. The setting of mechanical and rheological parameters in specifications is necessary and helpful, but probably insufficient to embrace and control such a key element in the practical implementation of foundation construction. The proper selection, design, implementation and supervision of slurries on site requires both from Contractors and Engineers to understand how different slurries do function. Only with this knowledge the right decisions in slurry operations can be made. This talk is directed to give some help to both, Contractor’s and Engineer’s, in understanding how different type of slurries do work. (Which ones should be preferred in what kind of soils.) The better knowledge will help the Contractor to control cost and enhance production. The Engineer will be able to assist in arriving at the appropriate technical choices and include in the specifications.

Sep 1, 2022

By H G. Poulos

"This paper sets out a simplified approach by which the practical foundation designer can undertake the relevant calculations to satisfy the requirements for deep foundation design in seismic areas. The following matters are dealt with:a. Design issues that should be addressed;b. Pile design for axial loading, including the possible effects of liquefaction;c. Pile design for lateral loading where liquefaction does not occur;d. Pile design for lateral loading where liquefaction does occur;e. Measures to mitigate against liquefaction effects.The paper is a modified version of a paper presented in 2013 to the 19th NZGS GeotechnicalSymposium, Queenstown, New Zealand.1. INTRODUCTIONConsideration of the effects of earthquakes and seismic loadings is an increasingly important aspect of modern foundation design, and most contemporary standards have a mandatory requirement for such consideration. For example, the Australian Piling Code, AS 2159-2009, states that “a pile shall be designed for adequate strength, stiffness and ductility under load combinations including earthquake design actions”. However, the methods by which such considerations can be undertaken are generally not set out in the standards, and many approaches have been utilized, ranging from very simplistic methods to extremely complex computer analyses. Accordingly, there appears to be scope for an approach that is soundly based but which is neither too simplistic nor too complex.Poulos (1989) has suggested that there are three categories of analysis and design, as follows:1. Category 1: empirical methods.2. Category 2: simplified but soundly-based methods.3. Category 3: more comprehensive methods that are soundly-based, and site-specific.The objective of this paper is to set out a systematic but simplified approach which falls into Category 2 above, and by which the foundation designer can undertake the relevant analyses to satisfy the foundation design requirements for seismic regions. Emphasis is placed on methods that do not require “black box” software or which employ complex soil models in which the physical meaning of the parameters is unclear."

Jan 1, 1900

By Emad Farouz, Ehab S. Shatnawi

"The increasing demand for small deformations and high-capacity drilled shafts without enlarging drilledshaft diameters has motivated the development and increasing use of a base grouting (BG) technique. This technique has been demonstrated to improve drilled-shaft capacity, especially for shafts tipped into loose cohesionless soils. Nevertheless, there remains considerable uncertainty in predicting the performance of base-grouted shafts, particularly for shafts tipped into cohesive soils. To date, there are only two documented design methods for estimating the axial geotechnical resistance of base-grouted shafts: Tip Capacity Multiplier (TCM) and Axial Capacity Multiplier (ACM) methods. A comprehensive test program was carried out during the design phase of the Wisconsin Zoo Interchange project to help optimize the flyover ramp’s foundation design. The test program included installing and testing one base grouted shaft and one ungrouted shaft at two sites with different ground conditions. Based on test results, it was concluded that prediction of the TCM method is well correlated with the measured values for both cohesive and granular soils; however, both methods tend to underestimate the axial resistance. Results also highlighted the importance of the base-grouting criteria in taking full advantage of the base grouting.INTRODUCTIONBase-grouted drilled shafts (BGDS), also known as post-grouted drilled shafts, consist of conventionally installed drilled shafts that contain access grout tubes placed within the shaft during construction. After installing the drilled shaft and achieving the pre-established concrete strength, grout is injected at the shaft tip through the access grout tubes to improve soil behavior around the drilled-shaft base. The tip grout injection improves the overall shaft capacity and reduces settlement through Densifying the in situ soils, compressing any debris left by the drilling process, preloading the soil beneath the tip to mobilize the shaft base resistance within service limits, increasing the tip area, and increasing the side resistance in the lower portion of the shaft."

Jan 1, 2016

By Haoran Zhang, Chu Ho

A recent design-build project in New York involved various degrees of additions and improvements to four existing transit stations. Reuse of the existing foundations was considered a more sustainable alternative than constructing new foundations for the project. This approach mitigated the extent of demolition work and limited the amount of downtime for track operations. A key challenge for reusing the existing foundations was the lack of as-built drawings. In order to obtain some measure of confidence for the proposed foundation reuse, non-destructive investigation technology was adopted to evaluate the structural integrity of the piers and foundations. A total of 47 piers for the existing passenger platform were investigated for possible reuse. Several test pits, excavated to verify the foundation type and configuration, indicated the piers were founded on a combination of shallow footings and drilled shafts. Pile integrity tests were performed to verify the length of the drilled shafts. Geotechnical capacity of drilled shafts was evaluated for side friction and end bearing resistance, and confirmed using a proof load test conducted from the existing platform structure. This paper presents the investigation methodology and discusses the approach adopted for geotechnical design of the existing foundations for reuse.

Sep 8, 2021

By O. Craciun, C. A. Bridges, M. Cai, J. Sugawara

There are a number of methods that can be adopted for predicting the ultimate lateral resistance of a free-head rigid pile, from the conventional Brinch Hansen and Broms solutions to three-dimensional finite element analyses. Often these methods give rise to significantly different pile ultimate lateral capacities which could lead to either unsafe or too conservative designs. It is also well known that finding a rigorous and practical solution is challenging due to the complex three dimensional and nonlinear soil-structure interaction. This paper reviews some of the most common methods and produces results of pile ultimate lateral capacities embedded in cohesive or cohesionless soils. Subsequently, a finite element analysis is performed using PLAXIS 3D modelling under the same design conditions. Based on comparison of results, limitations and advantages are highlighted, and the most suitable method is proposed from a practical point of view.

Nov 1, 2022

Jan 1, 1998

By Robert E. Schock, Eric J. Risberg

"Less than 20,000 years ago, the last of the glaciers retreated from the Chicago region. They left behind sheets of glacial clay till underlain by dense, over-consolidated till (“hardpan”) below which is the limestone bedrock, found about 100 ft (30.5 m) below street level. The most notable feature in this profile is the unusually soft clay till that has historically been called “Chicago Blue Clay.”But the founding fathers of Chicago really didn’t care about what was under the ground. They recognized the importance of the city’s location as a potential trade and transportation hub. With access to the East through the Great Lakes and access to the West through the Mississippi River system, the viability of the city was evident. Chicago’s population grew rapidly. The city continued to grow through the Civil War years, but was dealt a devastating blow in 1871 by the Great Chicago Fire, leaving the city in ruins. The Birth of the SkyscraperAfter the cleanup of the Great Fire came the first real building boom in Chicago’s history. During this era, buildings were generally founded on shallow footings bearing on sand or clay. Many multistory buildings were constructed between 1880 and 1890 on spread footings. The first tall buildings were constructed with load bearing masonry walls. These early tall buildings suffered significant settlement as the soft clay underwent consolidation.The Home Insurance Building, built in 1885, was 12-stories tall and is generally acknowledged to be the first “skyscraper” in the U.S. It was the first building constructed with an iron skeleton frame instead of load bearing masonry walls. Spread footings were used under the interior columns in an effort to better distribute the loads, but the building still experienced large settlements.Construction began for the Monadnock Building in 1891. The 17-story building was built using load bearing walls 7 ft (2.1 m) thick, supported on rail-grillage footing foundations. When completed in 1893, the Monadnock Building boasted the title “World’s Largest Office Building.” The total building settlement over the past 125 years has been measured at over 20 in (0.51 m). The engineering community in the late 19th century observed settlement, but did not yet understand the process of consolidation of the soft clay beneath the city. During this time, many of the new buildings required structural repairs during and after construction; the problem was especially acute in buildings where highrise towers joined lower podium structures."

Jan 1, 2016

By Rick Piovesan, Pramod Rao, Nihal Bohra, Mark Wahler

"This paper discusses the approach followed for the geotechnical design of 355 mm and 457 mm diameter driven open-ended steel pipe piles used for a gas plant at a green field site in Pilbara region in Australia. The principal bearing layer at the site comprises of calcareous Red Bed soils and weak rock, which is the typical geology along a significant length of the northern Western Australian coastline with carbonate content up to 70%. The uncertainty associated with the mechanical behavior of the calcareous soils and cemented soils (weak rocks) presented design challenges in the selection of appropriate pile design method and design parameters for pile capacity estimation during Front End Engineering Design (FEED). The American Petroleum Institute (API)-based design methodology was adopted. The representative design parameters for the Red Bed weak rock were established by treating the weak rock as clay with undrained shear strength as one-half of the characteristic unconfined compressive strength (UCS) value. Both statically load tested and CAPWAP (Case Pile Analysis Wave Program) estimated ultimate axial pile capacities on 25 early pre-production indicator piles demonstrated that the API design methodology for siliceous soils provides reasonable prediction of axial pile capacity in the red bed soils/weak rock and no reduction to API computed axial capacity due to carbonate content is warranted. The results also demonstrated that penalizing axial pile capacity solely based on carbonate content is not appropriate.IntroductionA gas processing facility was proposed to commercialize the gas reserves located 130 km offshore from the north-west coast of Western Australia (WA). The project site is a green field site located in the Pilbara region along the northwest coast of WA. Specific information regarding the site has been withheld due to confidentiality reasons. The site layout is shown in Figure 1.The site comprises low-lying tidal flats, clay pans and sand dunes covered with low scrub. The onshore site levels vary from elevation 1 m to 10 m AHD (Australian Height Datum), with the largest proportion of the area (excluding sand dunes) between elevations of 1 m and 3 m.The onshore facilities are to comprise a liquefied natural gas (LNG) plant site, a construction camp, the land-based portion of the materials offloading facility (MOF), roadways, and borrow pit areas.The existing ground levels within the process train area, where pile load testing was performed, vary from over 7 m AHD where the summits and peaks of the central dune exist to typically 1 m to 2 m AHD towards the east and west edges of the dune. The proposed finished grade for the process train is set at 7 m AHD."

Jan 1, 2015