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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 Brandon M. Robinson, Osman F. Besler, Dominik Gaechter

With the increase in population over the last decade, and anticipated population growth over the coming years, Norway is making significant investments in the Country’s infrastructure. Part of this investment in development starts with the Intercity development project in South-East Norway, which is the largest transport project in Norway. The Intercity Development project consists of 270 km (167 mi.) of new doubletrack rail, capable of train speeds reaching 250 km/h (155 mph). The new stations are centrally located in the major cities, in South-East Norway, to provide the benefit to as many citizens as possible. The goal of the project is to reduce the increase in traffic, which is coupled with an increase in population, and reduce the travel times between the cities. The Intercity Development Project has an anticipated completion date of 2034. The Sandbukta-Moss-Såstad (SMS) project, part of the Intercity development, includes 10 km (6.2 mi) of new double-track railway and is situated on the Østfold Line, near the city of Moss, Norway shown in Fig. 1. The 10 km SMS-section covers three open stretches and two tunnels, including 630 m (2,066 ft) substructure for double-track railways on the open line at Sandbukta. The Moss tunnel is a 1720 m (5,643 ft) long tunnel from Sandbukta to Moss center, including a 420 m (1,378 ft) long concrete culvert. The new Moss station includes an 800 m (2,625 ft) long station area. The Carlberg tunnel is a 2350 m (7,710 ft) long tunnel from Kleberget to Carlberg, including a 200 m (656 ft) long concrete culvert.

Sep 8, 2021

By Shawna Munn, Nadir Ansari, Toben Jerry

With ever increasing demands on space in urban environments and smaller available footprints, buildings are being designed to increasing heights to meet the need. This case study discusses the increasing challenges in developing projects within urban environments with smaller available footprints and increasing building heights. The One, Canada’s tallest residential building under construction will stand at 85 storeys and is located at one of the most prominent and built up intersections in Toronto, Yonge Street and Bloor Street. This led to many challenges in design and construction of the shoring and foundation work, including the required design capacity of the foundations for the supertall building and proximity of the large diameter drilled shafts to the excavation shoring wall. This case history describes the shoring design option evaluation, performance, and lessons learned to date throughout construction of the building foundations within a small congested site. PROJECT OVERVIEW The One, Canada’s tallest residential building under construction by Mizrahi Developments, is a supertall building that will stand at 85 storeys and 306 m (1005 ft). The first 18 floors will be comprised of retail, restaurants, and hotel with luxury residential condominium units in the tower above. The project is located on the Southwest corner of Yonge Street and Bloor Street, one of the most prominent and built up intersections in Toronto. The L-shaped excavation measures 58 m by 47 m (190 ft to 154 ft) and ranges from 22 m to 28 m (72 ft to 92 ft) in depth with one internal corner projecting 11 m (36 ft) into the site.

Jan 1, 2019

By John P. Turner, Mark Jen, Bobby Daita

"The Port Authority of New York and New Jersey is replacing the existing Goethals Bridge built in 1928 which is deemed to be functionally obsolete. The replacement bridge will consist of a dual cable-stayed Main Bridge crossing the Arthur Kill with elevated approach spans connecting Elizabeth, New Jersey and Staten Island, New York. The main bridge towers are supported on a group of six nine-foot diameter drilled shafts that transition into a pier cap. The anchor and approach piers are supported on two column bents with each column supported on a single drilled shaft. The 4.5 to 10 feet diameter drilled shaft foundations have permanent steel casing to rock and socketed into bedrock. Subsurface conditions consist of Passaic Formation bedrock overlain by varying thicknesses of overburden soils. The foundation design assumes permanent casing extending a minimum 2 feet into the weathered bedrock. Rock socket lengths below the permanent casing vary between one to two shaft diameters based on the quality of the bedrock. The reinforcing design was based on AASHTO LRFD minimum requirements, force demands, seismic detailing requirements and also considering the continuity between the shaft and socket.The bridge is currently under construction with approximately 70 percent of the foundations installed. Several field conditions encountered at various stages of shaft construction between casing advancement and concreting required design and construction modifications. Based on the driving method and the quality of the bedrock, the tip of the permanent casing hit refusal either above or below the design elevation, requiring modifications to the drilled shaft design and its reinforcement. This paper provides an overview of the general subsurface conditions at the site and its impact on foundation design and discusses the detailing worked into the design to accommodate tip elevation variations, as well as various foundation design modifications in response to actual conditions encountered during construction."

Jan 1, 2016

By Lawrence F. Johnsen, Felix Ferrer, Dino Tomasetti, Cassandra A. Wetzel

"A 17 story building was constructed at the Brooklyn Navy Yard on a site with a long history of development. Most recently the site supported a dewatering well and craneway to service two adjacent drydocks. The subsurface conditions generally consist of the following strata and approximate depths: miscellaneous fill and debris to 20 ft., organic soils to 35 ft., liquefiable sand to 45 ft., varved clay to 65 ft., glacial till to 95 ft. and gneiss bedrock.Hollow core bar piles replaced 18 in. diameter caissons on a 1.67:1 basis. The resulting service loads on the hollow bar piles were 600 kips compression, 21 kips lateral, 180 kips tension and 450 inch-kips moment. The top 30 feet of the hollow bar was cased with a 16 in. x 0.375 in. Grade 50 steel pipe. The piles were socketed 6 feet into bedrock. An extensive load testing program confirmed the axial and lateral load capacities. The paper will also discuss some adjustments to the installation procedure based on the load test program.PROJECTThe hollow bar piles were installed to support a 95,000 sf footprint, 17-story office building at the Brooklyn Navy Yard. The Brooklyn Navy Yard was first developed in the late 1700’s to build merchant vessels. The federal government purchased the old docks and adjoining 40 acres in 1801. The site was an active U. S. Naval Shipyard from 1806 to its decommissioning in 1966. At its peak in World War II it employed 70,000 people, 24 hours a day. Since 1966 the property has been converted to private manufacturing and commercial activity.The site is located between Dry Docks 2 and 3. The adjacent drydocks extend 40 to 43 feet below grade. The drydock walls are restrained by tierods extending back to deadman anchors. The site is also underlain by piles that were installed to support rail lines and a craneway. The building footprint also covered an 85 ft. wide, 70 ft. deep dewatering well which had a thick slab. The structural engineer for the project, ARUP, designed the building to span over the dewatering well.SUBSURFACE CONDITIONSIn September 2014, Langan Engineering conducted a geotechnical engineering study for the project. Figure 1 provides a subsurface profile through the long axis of the site. The general soil profile was very erratic but generally consisted of miscellaneous fill and debris to 20 ft., organic soils to 35 ft., liquefiable sand to 45 ft., varved clay to 65 ft., glacial till to 95 ft. and gneiss bedrock. The fill contained numerous obstructions from the over 200 years of site development. The organic soils were mostly very weak and compressible organic silt. The depths and thicknesses of the varved clay, and sand varied"

Jan 1, 2017

By Schmitz Stefan, Stephan Jee-Sun

"Due to the reunion of Western and Eastern Germany in the late 80’s, a multitude of infrastructure projects had to be executed. A good portion of these projects required improvement of the motorway system. In the southern region of Leipzig, in the eastern part of Germany, it was required to connect two existing motorways. Parts of the new motorway pass old strip mining areas. These strip mining areas consist of up to 70m thick backfill material. Especially the upper 20m are very inhomogeneous soil material with a very low bearing capacity. In order to increase the bearing capacity, to decrease the differential settlements and to homogenize the soil parameters, soil improvement using sand-gravel columns was required. Bauer Spezialtiefbau GmbH executed the installation of approx. 711,000 linear meters of columns with a length from 5 m to 25 m. For the project, 11 rigs with frame leads up to 40m were used to install the 43,000 columns with a diameter of 0.8m in 27 weeks.1. INTRODUCTION1.1 Site LocationThe construction site is located in the south-eastern part of Germany, in the south west of the city Leipzig.The area to be treated had a size of approx. 500,000 m² to allow the construction of dam/embankments and a highway bridge.1.2 Required WorkIn addition to the general earthworks and the installation of geogrids and fibre mats, a total amount of more than 710,000 linm of Gravel-Sand Columns with different lengths due to the given soil conditions had to be installed:•nos. 4,206 Columns length 5m ? 21,030 linm•nos. 4,581 Columns length 10m ? 45,810 linm•nos. 10,820 Columns length 15m ? 162,300 linm•nos. 19,634 Columns length 20m ? 392,680 linm•nos. 3,574 Columns length 25m ? 89,350 linmFor the installation of the columns Gravel-Sand with the grain size of 0/32mm was used. The total amount of Material was 580,000mt"

Jan 1, 2015

By V K. Panwar, Sampat Raj

At a Fertilizer plant located in the southern part of India, 74 numbers of pump foundations have shown non-uniform settlements causing the tilting of pump foundations under self-weight primarily due to the presence of varying thickness of the heterogeneous subsoil beneath the pump foundations and soil erosion because of water seepage through deeper excavations in the close vicinity. Various corrective measures have been explored and taking due cognizance of the prevailing subsoil conditions, site constraints, and constructability aspects, micropiling has been adopted. This paper presents the site problem and details of remedial measures adopted for rehabilitation of the distressed pump foundations. The main objective of this paper is to provide guidelines for designer during design and detail engineering stage to avoid similar nature of problems and also to provide a solution concept to tackle similar nature of problem(s) if encountered at site.

Nov 1, 2022

By Shahid Islam, Lucian Bogdan

"The maintenance of infrastructures has been of particular concern to the engineering community. As the world’s infrastructure expands and existing infrastructure ages, monitoring and evaluation of the structures have become more critical than ever. A large number of retaining walls, tie backs, slope stabilizations and piles are designed using pre-stressing steel. Many piles and drilled shafts are designed using reinforcing steel. There are few testing methods available to assess these tension and compressive forces. High cost, complicated equipment and limitation of space often prevent these methods from being implemented. DYWIDAG-Systems International (DSI) has been involved in the development, testing and utilization of DYNA Force® sensors to measure the force in the anchors during construction and at any time during the lifetime of the structure. They can be used for bare, epoxy-coated, galvanized and greased-sheathed steel in the bonded, un-bonded, grouted or un-grouted length of the anchor. The sensor is robust and requires no maintenance. Sensors have received attention in terms of accuracy, performance, ease in installation, durability, and cost effectiveness. This paper describes its application in tie-back and anchor force monitoring of retaining walls and bridge abutment and compression forces in drilled shaft reinforcing steel where the data were collected manually, automated and remotely.INTRODUCTIONOur infrastructure is expanding and the existing infrastructure is aging. Some structures are expensive to maintain and some occasionally fail. There is a large demand for implementing health monitoring of structures. Many tie-backs, retaining walls, dams and other geotechnical structures are post-tensioned and many of them need repair using a post-tensioned system. On many occasions during construction and service life of the structure, it is useful to know the force in the post-tensioning and anchor system. Many piles and drilled shafts are designed using reinforcing steel and the compressive forces in reinforcement are unknown. Although there are many methods to measure the tendon force, most of them are cumbersome, expensive, and the accuracy varies depending on the method used.The elasto-magnetic (EM) technology is a novel approach to monitor forces in steel elements. The DYNA Force sensor is built based on EM technology (See Fig. 1). It is composed of a primary coil and a secondary coil (sensing coil). By passing current through the primary coil, ferromagnetic material is magnetized. The sensing coil picks up induced electromotive force that is proportional to change rate of applied magnetic flux (Faraday's law) and relative permeability. As permeability of core changes, output voltage changes. The output voltage is calibrated to measure the force. A readout unit is designed to magnetically energize the steel through the sensor and measure the response of the steel to the process. The readout unit then converts the response into a direct force reading. The sensor has an embedded thermistor which allows for temperature compensation. Due to the diversity of the magnetic property of steel, calibration is done for each type of steel allowing the sensors to perform at their highest accuracy."

Jan 1, 2017

By Georg Breitsprecher

The technique of Stabilising Columns (product names are for example "Stabilisierungssaulen" (STS) or "Coplan Stabilisierungs-verfahren" (CSV)) is gradually becoming well accepted for ground improvement. The installation, dimensioning and quality control are standardized by DGGT (German Association for Geotechnique), working committee 2.8, of which until now only part one exists for dry columns. This paper describes the installation and testing of stabilising columns for a ground improvement project. To achieve comparable results in testing both ready mixed concrete and dry binder had been used for production.

Jan 1, 2006

By P. J. Nicholson

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

Jan 1, 2010

By Armin W. Stuedlein, Steven R. Saye

The differences between calculated axial pile capacity and the capacity realized during and following installation has long presented a significant concern for foundation engineers and contractors. Such differences have increased in prevalence with the increased use of larger diameter steel pipe piles and the significant increase in design-build contracting. The writers present concepts to close the gap between calculated axial pile capacity and the capacity realized during and following installation of driven pile foundations, including: (1) pile set-up in plastic soils, (2) limitation of re-driving of piles after setup which serves to reduce pile capacity, (3) the use of a vibratory hammer to install piles in cohesive soils disturbs the supporting soils and reduces the pile side resistance capacity significantly, and (4) long pile installation times for open-ended piles can damage the pile side resistance. Examples are presented from practice to illustrate these concepts and to guide pile installation planning to recognize the installation impacts and either consider alternate installation approaches or to properly consider the installation impacts during design.

By Liiban A. Affi

The most difficult task of designing multilevel tieback walls for deep excavation support is the determination of lateral stresses. These lateral stresses act not only on the shored height, but also on the embedded portion of the soldier pile, all the way down to the pile tip. Examples of lateral stresses include uniform surcharge load (soil spoils or equipment), strip load surcharge from Cooper E80 (train loads), line load surcharge (exterior footing or retaining walls), and point loads (cell tower). In this paper we will discuss the various surcharges, do step by step example calculations and show how to take the total lateral stress output and present the design pressures for direct use by the substructural designer. Included is a case study from a project Anaheim Hills, California, USA.

Jan 1, 2010

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 A. Rod Kern, Michael A. McNicholas, Yaser Taheri

Deep foundations were required for construction of an 18,000 ft2 (1,672 m2) 4-story office building and an adjacent 23,750 ft2 (2,206 m2) 5-story parking garage in Queens, New York due to an existing uncontrolled fill layer ranging from 15-20 ft (4.6 - 6.1 m) in thickness beneath the building footprint. The geotechnical engineers for the project initially selected auger cast-in-place (ACIP) piles over driven piles to limit the impact of noise and vibrations on the surrounding neighborhood. Ultimately, drilled displacement piles (DDP) were installed since this method offered a more economical solution that would generate the required pile capacity with shorter drill depths and would also mitigate spoils volume. During installation of test piles by the geotechnical contractor retained for the foundation work, multiple unanticipated soil conditions were encountered that would adversely affect the constructability of the piles. The existing fill contained significantly more natural and manmade obstructions than expected and the underlying glacial soil became too dense to penetrate at shallower depths than anticipated. This paper discusses how these issues were overcome through pre-drilling and the use of detailed instrumented test pile data coupled with in-house engineering capability to proactively re-evaluate minimum pile lengths at any given location and keep the project on track. INTRODUCTION Geotechnical work in the New York City market presents soil conditions that can be highly variable and challenging due to the presence of uncontrolled urban fill placed over the native soils. Construction in this area can therefore pose many unforeseen challenges, even with detailed geotechnical analysis being performed at project sites. A case in point is a construction site in Queens, New York. The proposed site development consisted of construction of a 4-story office building with a footprint of 18,000 ft2 (1672 m2) and a stand-alone 5-level parking garage with a footprint of 23,750 ft2 (2206 m2), together with associated new pavements and utilities. The site is bordered by a mix of commercial buildings and residential properties on all sides. Depth of the uncontrolled nature of the fill extended up to 20 ft (6.1 m) below street grade. Given the significant cost associated with removal and replacement, deep foundations were recommended to bypass the unsuitable soils and support the structures at depth where good bearing material existed.

Jan 1, 2019

By Ramanathan C, Prasad P. V. S. R

The most critical challenge for any large size storage structures to be constructed on soft compressible soils is bearing capacity and consolidation settlements. Consolidation is the time dependent phenomena, as expulsion of water from soil voids on application of external load will take longer period. It is mainly influenced by soil consistency, permeability, thickness of compressible stratum and presence of free draining layers. This study deals with the foundation solution of a large size Mounded Storage Vessel (MSV) to be constructed on thick compressible stratum whose loading intensity is around 155 kPa and the estimated settlements are greater than 400 mm. Hence, the foundation solution using vibro stone columns is adopted as an effective technique to address the challenges of excess settlements and inadequate bearing capacity. Further to keep settlements within the permissible limit of 50 mm, preloading technique with 60% of actual loading intensity will be utilized. The consolidation analysis of stone column reinforced foundations is carried based on the method given by Han and Ye (2001). The quality of the stone columns is ensured by real time quality control measures and the performance of the stone columns shall be ensured by vertical load tests. Ground settlements was closely monitored with proper instrumentations and the actual degree of consolidation has been verified by Asaoka’s (1978) method.

Sep 1, 2022

By Joshua C. Adams, Les Chernauskas, Edward L. Hajduk

"Drilled shafts are increasingly being used to support bridge and building foundations. Because these foundations usually carry very high design loads and often serve as non-redundant, single load carrying units, these foundation systems need a high level of quality control (QC) and quality assurance (QA) during construction. One such method for providing QC/QA is crosshole sonic logging (CSL) testing, in which ultrasonic signals sent across the drilled shaft concrete assess concrete quality.CSL testing is an effective tool to evaluate the integrity of the in-place drilled shaft concrete. While typically used to evaluate drilled shaft concrete after construction, CSL testing can also be used to evaluate drilled shaft repairs. This application can be difficult, given the variability of repair methods and material properties. CSL testing can also be adversely affected by the condition of the concrete/access tube bond, leading to false anomaly detection and/or inability to evaluate concrete integrity effectively. This phenomenon, called access tube debonding, is often located in upper portions of the drilled shafts where large changes in groundwater occur, such as within tidal zones.Two case histories showcase innovative uses of CSL testing to deal with consistent access tube debonding and to evaluate drilled shaft repairs.CSL OverviewCSL testing involves placing ultrasonic transmitters and receivers in access tubes installed in the drilled shafts prior to concrete placement. Concrete quality is assessed by examining the First Arrival Time (FAT) and relative energy of the signal sent between the transducers. If the distance between the access tubes is known, an apparent signal velocity (i.e., wave speed of the ultrasonic signal through the concrete) can also be determined and used to assess concrete quality.Common CSL testing practice consists of simultaneously raising the ultrasonic transmitter and receiver and recording the ultrasonic signals with respect to depth. This results in a 2D examination of the"

Jan 1, 2009

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By George Burnhart

"Sonic drilling is a relatively new technology even though it has been in development since the late 1940s. It was initially funded by the U.S. petroleum industry and then, in the late 40s, Russian scientists worked on developing sonic drilling, their interest based on drilling rates 3 to 20 times that of conventional methods. In the early 1960s, the Shell Oil Company backed research that resulted in a down-hole device with a series of eccentric weights driven by drilling fluid to generate vibration. Hawker Sidley, in the early 1980s, developed the first modern prototype sonic drills in Vancouver B.C. and the North Star Drilling Company in Minnesota became the first contractor in the U.S. to operate sonic equipment in 1985. In 1994, North Star became a division of Boart Longyear, headquartered in Salt Lake City, Utah.What’s Unique about a Sonic DrillA sonic drill rig appears and operates very much like any conventional top-drive rotary rig. The key difference is that a sonic drill has a specially designed hydraulically powered drill head, containing oscillators, that generates adjustable high-frequency vibratory forces. The sonic head is attached directly to the drill pipe or outer casing, sending the high frequency vibrations down through the drill steel to the face of the drill bit. This creates displacement, fracturing or shearing action depending on the material being drilled. The oscillator uses two eccentric, counter-rotating balance weights or rollers that are timed to direct 100% of the vibration at 0 degrees and 180 degrees. An air spring houses the oscillators and separates the vibration from the drill rig itself. The vibratory frequency is controlled to suit operating conditions and to achieve optimum drilling rates.When the vibrations coincide with the natural resonant frequency of the steel drill rod or casing, a natural phenomenon called “resonance” occurs. It allows the rig to transfer timed vibratory energy into the top of the drill string, utilizing the natural stored energy of the steel. This causes the drill string to use inertia and act like a flywheel delivering tremendous amounts of energy directly to the bit face. In friendly overburden formations, a sonic drill rig can achieve penetration rates of one ft per second."

Jan 1, 2008

By Thomas J. Kennedy, Michael D. Bennett

The study of geotechnical history is well-established. Most geotechnical practitioners, teachers, and graduate students have some grasp of the origins of the field. However, this understanding often consists of a jumble of names and anecdotes. This paper discusses how a deeper comprehension of geotechnical history can benefit academia and practice alike and describes how the authors have begun a wide-ranging study of the subject. The paper reviews the dual-track methodology the authors have generated for the study, which consists of written articles about different works in geotechnical history and a database tracking how often pieces have been cited in geotechnical literature. The first technique has shed light on aspects of geotechnical history such as the connection of the Darwin family to the origins of geotechnical engineering, the St. Francis Dam failure of 1928, and the rivalry between theoreticians and practitioners in the early days of the field. The second has helped quantify subjects such as the outstanding contributions of Karl Terzaghi, the disagreements between Terzaghi and Donald Taylor, and the specialization of the field over time. The paper concludes by discussing the authors’ planned future work on geotechnical history.

Oct 1, 2022

"Standing 92 stories high and just over 1,362 ft tall, Chicago’s Trump International Hotel and Tower is perfectly positioned at the center of one of the world’s most impressive skylines.The Tower serves as a link between its famous predecessors, Willis Tower (formerly, the Sears Tower) to the south and the John Hancock Building to the north. Originally planned to be the world’s tallest building, the project was scaled back when the developers started questioning the need for super-tall buildings after the September 11, 2001 terrorist attacks. In its River North neighborhood, Trump Tower dominates the skyline as a symbol of Chicago’s last great building boom, standing triumphantly over other high-profile projects that have been postponed due to current economic realities.It is often said that the three most important factors in real estate are location, location and location. This maxim was not forgotten by The Trump Organization when the site was selected for the International Hotel and Tower. Located two blocks west of Michigan Avenue and Chicago’s famed Magnificent Mile, the site is bound by the historic Wrigley Building to the east, Wabash Avenue to the north and west, and the Chicago River to the south. The building’s position along a bend in the Chicago River allows visitors and residents unobstructed views to the mouth of the Chicago River and Lake Michigan. Site ChallengesUnderneath the site there are approximately 10 to 20 ft of sand and urban fill underlain by soft Chicago blue clay. At 75 ft in depth, the soft clay transitions into Chicago hardpan, a very hard till that was consolidated by the glaciers over 10,000 years ago. Below the hardpan, the till turns granular with cobbles, boulders and water under pressure. Bedrock is about 100 ft below existing grade and has a weathered surface with fractures and clay seams. Unweathered limestone bedrock is sound and hard with unconfined compressive strengths of 10,000 to 20,000 psi."

Jan 1, 2009