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By W. Morgan NeSmith

A drilled displacement pile program was utilized for the expansion of an existing power plant in Cohasset MN adjacent to the Mississippi River. The drilled displacement (DD) pile is an innovative foundation type that provides exceptional value in some geologies. In the U.S., DD piles have typically been used in coarse-grained soils due to the large friction capacities that can be generated by the piles in these conditions. This project was the first large scale experience for the project team where it was anticipated that significant portions of the DD pile capacity would be developed in primarily fine-grained soils. The project site consisted primarily of variable amounts of fill overlying predominantly low plasticity alluvial silts. In some cases, alluvial silty sand layers were encountered within the expected pile installation depths. Alluvial sands were typically encountered below the silts, in some cases within the expected pile installation depths. The project team developed a probe and pile load test program to address the variable subsurface conditions across the site. The program included monitoring various parameters (including applied torque and tool penetration rate) during the drilling portion of the pile installation using recently developed data acquisition techniques. This data was used to estimate the rig energy, or Installation Effort (IE), required for pile installation. IE profiles from the test and indicator piles were compared with subsurface data available from a number of previous site characterizations. Additionally, Cumulative IE values were compared to an in-house database of IE vs. DD Pile Capacity. Final production pile toe levels were based primarily on IE values selected from this comparison. The IE data collected during production was also used to address large variations in pile-cutoff elevation (relative to a fairly uniform ground surface elevation).

Jan 1, 2008

By Nicholas P. Gura

This paper presents the analysis, design, and load test program results for drilled shafts to support a 70-story hotel tower and associated 10 story podium structures located in Las Vegas, Nevada. A mat foundation for the structure, although feasible, would have produced undesirable differential settlements within the high rise tower footprint and at the interface with adjacent lower level podium structures. The resulting foundation system solution for the 70-story, approximately 800-foot long hotel tower was four-foot diameter drilled shafts, extending 100 below shaft cutoff. The design compression capacity for the four foot diameter drilled shaft was 5,000 kips. The load test program proved that the unique Las Vegas valley geology lends itself to efficient installation, precluding the need for engineered slurry or casing. The load testing program included the installation of two four-foot diameter test shafts to 100 feet below theoretical cutoff and the performance of two highly instrumented independent Osterberg load cell tests with maximum sustained test loads of 12,000 kips. Sonic caliper testing was also performed to document actual in-place shaft diameters and verticality. The load test program also provided information necessary for the foundation design of the podium structures. In addition to the tower?s drilled shaft load test program data, continuous flight auger (CFA) pile evaluation and testing was also performed. The CFA testing consisted of traditional ?top down? loading techniques and was performed as an alternative to the recommended shallow drilled shafts for the lower level podium structures. The results of the CFA test program provided supplemental, insightful soil friction data which was used in conjunction with the drilled shaft test program data in evaluating the most appropriate support for the lower level structures.

Jan 1, 2007

By Matthew Janes

The installation of piles and casings is becoming increasingly difficult as restrictions on vibration become common in major urban areas. The use of high frequency, resonant excitation of a pile or casing permits ease of installation of sections to great depths with near imperceptible vibrations as close as 1 pile diameter. The new Resonant Driver is able to excite a pile at its resonant frequency (up to 150 Hz or 9000 VPM) to produce elevated levels of acceleration, force and displacement in the pile. The combination of extremely high acceleration and controlled levels of displacement allow the pile to slice through varied soil with almost no vibration translated into the ground. In direct comparisons between conventional vibrators and impact hammers the Resonant Driver produces less than 1/50th the vibration. The Resonant Driver results in ground vibration of between 1/20 and 1/40 of common limit levels (1 cm/s or 0.5 in/sec) as close as 1 pile diameter. At a distance of 5 m (16 ft) from the pile or casing vibration levels approach imperceptible levels. The Resonant Driver uses a proprietary algorithm to tune the drive vibration to the changing natural frequency of the pile as it is driven into the ground. By maintaining resonance the energy in the pile is built up like in a flywheel on an engine or a child on a swing. This build up of energy aids in driving and significantly reduces waste. Recent experience using the Resonant Driver is proving the technology can drive a variety of steel pile and casing sections through varied soils. Continued use of the Resonant Driver will create a data base of various pile and casing sections, soil types and achieved capacities.

Jan 1, 2008

"Boston’s Central Artery passes beneath nine active railroad tracks carrying commuter and Amtrak trains into South Station, the City's busiest rail terminal. These railroad operations had to remain in service throughout the construction of the “Big Dig”. The solution was to jack the tunnel under the tracks, rather than build the tunnel by more conventional means.Jacking of utility pipes is fairly common, but jacking boxes as big as a highway had never been done in North America, until the Big Dig came along.Soil freezing was decided upon as a means of stabilizing the soil under the tracks. This allows the tunnels to be jacked into place without soil caving when the soil is excavated at the leading face of the advancing tunnel boxes. Hundreds of pipes were driven into the ground between the tracks. Inside the steel pipes were smaller plastic pipes. A freezing plant near the railroad tracks pumped refrigerated brine into the inner plastic pipes. The brine ran out the bottom of the inner pipe, flowed up to the top inside the outer pipe, and was re-circulated to the freezing plant and back again into the ground. Over several weeks the circulating brine drew the heat out of the soil little by little, and froze the ground outward from the pipes. Soil FreezingThe plan required the construction of jacking pits in which the tunnel boxes could be constructed, and from which they could be jacked forward to their final locations, as described in the accompanying article. Once the jacking pit was built and the tunnel box constructed inside the pit, crews made an opening in the headwall of the pit to allow passage of the tunnel sections, excavated about three feet of the frozen soil, pushed the tunnel box ahead, and repeated the procedure again and again."

Jan 1, 2003

By Deep Foundation

Whenever an organization launches an initiative, the question arises whether that initiative has staying power. Or is the initiative, as is quite often the case, merely a fad; that is, just an activity that suddenly becomes popular, but which does not stay popular for very long. When the Federal Highway Adminis- tration (FWHA) started its Advanced Geotechnical Methods in Exploration (A-GAME) initiative, that question was addressed, especially considering the fact that up to 50% of major infrastruc- ture projects suffer impacts to schedule or cost due to geotechnical issues. Many of these issues relate to risks identified directly or indirectly to the scope and quality of site character- ization work. Effective site charac- terization is critical for recognizing. potential problems that may affect design and construction and for ensuring safe, well-performing and cost-effective projects. Grounded on that, knowledge of all available site investigation methods should continue to be shared widely and the application of those methods should be encouraged on an ongoing basis throughout the project lifecycle. The A-GAME initiative covers five technologies: Cone penetration testing (CPT), monitoring while drilling (MWD), electrical geophysical methods, seismic geophysical methods, and optical and acoustic televiewers. Of these, three soil and rock investigation methods were highlighted that are underutilized not only here in the U.S., but also in many places around the world: CPT: a well proven and established method for soil characterization that turned 90 last year, in which continuous in-situ data are col- lected quickly and consistently. Geophysics: the science that assesses the physical properties of the soils and rock using seismic and electrical techniques, which con- tinues to advance in leaps and bounds as the application of well- understood technologies become more powerful.

May 1, 2023

By Avi Shonberg

With the advancement of offshore wind farm projects towards deeper waters and larger wind turbine generators, founda- tion solutions other than the monopile have received increasing attention over the past 5 years. Monopiles are the most commonly used foundation solution for offshore wind turbines, with 82% in European waters founded on monopile foundations (EWEA, 2019). However, 2018 saw a record number of suction bucket jacket (SBJ) structures, which consist of a three-legged jacket sup- ported by a suction bucket at each leg (Figure 1), installed for offshore wind. applications. SBJs have now been installed successfully at the Borkum Riffgrund 1, Borkum Riffgrund 2 and Aberdeen Bay offshore windfarms. Suction-installed foundations, referred to in this paper as suction buckets, suction caissons, suction piles or suction anchors, have been widely used in the offshore industry since the early 1980s for a range of offshore applications predominantly as anchors for floating offshore structures - where they are "the most widely used anchor types for deep-water mooring applications" (McCarron, 2011). Suction buckets, installed using pumps that generate suction forces by creating a pressure difference between the inside and outside of the bucket, allow for the installation to be undertaken with minimal noise and without the use of mechanical force. Therefore, a key difference between suction-installed foundations and other foundation types is that the installation design, which must consider the soil type, soil strength and installation specific risks (for example, soil stratification with significant differences in permeability) may have a direct influence on the dimensions of the foundation. While the number of SBJS installed for offshore wind applications has increased significantly in recent years, the installation process for SBJ struc- tures is yet to become standard practice and is considerably more complicated than the installation process for mon- opiles. This paper provides a brief

Jul 1, 2022

By Shigenori Horikawa, Nobutaka Tanaka, Toshiro Hara, Kengo Yamamoto

"The CDM-LODIC method(Low Displacement and Control method), a modified the CDM(Cement Deep Mixing) method, reduces the ground displacement through the removal of in-situ soil equivalent to the amount of slurry injection using the continuous auger flight attached on the shaft above the conventional the CDM mixing tool. The reduction of ground displacement minimizes the impact on adjacent buildings and other infrastructures. Since the development of the CDM-LODIC in 1985, this method has been used for more than 900 projects with total volume of improved soils exceeding 5.3 million yd3 (7 million m3). The ground displacement that could be caused by deep soil mixing is controlled by balancing the volume of discharged soil and the volume of slurry injected for soil mixing. This paper presents the ground improvement work for the Sanriku Coast Expressway Project using the CDM-LODIC method to 1) control the ground displacement during ground improvement to minimize the impact to existing buildings and facilities and 2) utilize low height CDM-LODIC equipment to avoid potential damage to critical facilities in the vicinity of ground improvement area and avoid interference on the normal operation of the Ishinomaki Red Cross Hospital.INTRODUCTIONSanriku Coast Expressway is a reconstructed highway, which is part of an early restoration program to recover from the Eastern Japan Earthquake of March 11, 2011. This highway extends 223 mile (359 km) and connects the Pacific Coast regions of three prefecture of North Eastern Japan as shown in Figure 1. Along a section between Yamoto - Ishinomaki road, the highway was expanded from two lanes to four lanes to mitigate traffic congestion for the adjacent city center and hospital and to serve as an efficient transportation route for emergency or disaster relief needs as shown in Figure 2. Deep mixing ground improvement with an area replacement ratio of 50% was designed to provide settlement control under the new fill embankment of the expanded highway as shown in Figure 3. The original CDM treatment layout using 5.2ft (1.6 m) diameter columns is shown in Figure 4."

Jan 1, 2015

By Alan Christopherson

Nearshore construction projects often require installation of steel piles and specific methodologies of installing piles may adversely affect nearby species of concern. Water is an uncompressible medium which allows for easy transmission of energy through the water column. Energy transmission through water depends on the following factors for pile driving: 1) direct contact of the pile and the water; 2) the depth of the water column; 3) the size of the pile; 4) type of hammer; and 5) the energy of the hammer. Seasonal restrictions are usually the best practicable alternative for reducing habitat impacts when pile driving activities may adversely affect the species of concern. When seasonal restrictions are not practical other options need to be evaluated, including mitigation and noise attenuation devices. The broad array of mitigation options will not be discussed as part of this presentation but instead will focus on noise attenuation technologies. Dewatered cofferdams can be effective noise attenuators as they eliminate direct contact of the pile with water while driving. Also, introduction of a compressible medium, like air, near the energy source can provide sound energy attenuation. An unconfined bubble curtain is relatively inexpensive but is not effective in tidal marine projects or rivers and may have unacceptable secondary effects. Secondary effects must be evaluated as these can increase exponentially for larger projects. Secondary effects to the environment include air quality degradation from air compressor use, transportation costs for fuel and equipment, and the potential for injecting oily compressed air into the water column. The confined bubble curtain works well in nearly all environments. It usually is more expensive initially, relative to an unconfined air curtain, but there is less potential for harmful secondary effects. Generally, seasonal restrictions will be adequate to protect species of concern. However, there are conditions in which mitigation or one of the sound attenuation options should be utilized. Site specific factors, including the amount of energy being imparted into the environment, sensitivity of the species of concern, current, accessibility, length of time needed to complete the project, and the cost of the sound attenuation, should be factored into the permit evaluation.

Jan 1, 2013

By Paul Summers, Kevin Richardson, Willem (Billy) Villet, Paul J. Sabatini, Edward C. Clukey

"Between 2008 and 2009, more than 6,000, 23-m long deep mixing method (DMM) elements were constructed to support 124 concrete mats comprising the foundations for the process trains for an LNG facility. The Owner requested first-of-its-kind analyses and assessments to confirm the quality and reliability of the DMM foundation. This paper provides information on these assessments and the procedures used to ultimately conclude that a fit-for-purpose foundation system was constructed.During early phases of construction, several DMM test cores revealed nodules of unmixed clay in upper core samples. A comprehensive review of available DMM core information was undertaken. It was concluded that the amount of coring being conducted as part of the contractor’s QA/QC program should be increased to achieve a foundation system with the required level of reliability.Three-dimensional finite element analyses were completed considering various distributions of defects in the DMM elements and the effects of potential downdrag on DMM elements. Calculated mat settlements and mat stresses were compared to cases without defects in the DMM elements. Various distributions of loaded and unloaded mat areas and number and position (both in the subsurface and laterally) of defects were considered. Four (of the 124) mats were identified as potentially “at-risk”. The settlement performance of these mats is currently being monitored and, to date, performance has been acceptable.IntroductionThe foundation support system for the process train at a major LNG facility comprises more than 6,000, 23-m long DMM elements. The general subsurface stratigraphy at the project site comprises (from the ground surface): (i) up to 8 m of fill sand initially placed underwater building to a stable construction platform; (ii) up to 12 m of soft organic clay (Unit II clay); and (iii) clayey sand and sand layers becoming progressively denser with depth (Unit III sands). Each DMM element comprised two secant 1.5-m diameter DMM columns. DMM elements were typically arranged as cells enclosing one, two, or three DMM elements."

Jan 1, 2017

By Glen M. Bellew, James F. Mehnert

"The Kansas City District-United States Army Corps of Engineers has completed the design modification of a pile supported floodwall located along the Missouri River in Kansas City, Kansas. This deep foundation supported floodwall protects over 2 billion dollars in infrastructure, is approximately 17 ft (5.2 m) tall and is 1,446 ft (440.7 m) long. Design modifications included the addition of a row of drilled shafts and the addition of relief wells. Typically, deep foundation design is controlled by total stress analysis and undrained soil strength. Neither controlled design at this site, where effective stress and drained strength controlled. During high river stages, artesian pressures develop, leading to a reduction in both effective stress and pile capacity. Deep foundation analysis software available to the designer does not allow these effective stress conditions to be directly entered, so a unique way was developed to account for them. A load test was performed to verify the design. During load testing, the supporting ground was unsaturated and had effective stress conditions different from those that controlled the design. A load test evaluation process involving unsaturated soil mechanics was developed and performed. This paper will share both the effective stress design process used and the load test interpretation process performed.INTRODUCTIONThe Fairfax-BPU Floodwall is part of the Fairfax-Jersey Creek Flood Protection Unit in Kansas City, Kansas. The floodwall was built in the 1940s and currently provides Missouri River flood protection for over 2 billion dollars of infrastructure in the Fairfax Industrial Area. The floodwall averages 17 ft (5.2 m) in height, is 1,446 ft (440.7 m) in length and is divided into 35 separate monoliths. The originally constructed foundation support for each of these monoliths typically consisted of three rows of seven tapered steel monotube piles, each roughly 20 ft (6.1 m) in length. All monontube piles are tipped in sand, well above bedrock."

Jan 1, 2016

By Yoshinori Kurumada, Tatsuo Nagatsu, Keiji Uchida

"Cement deep mixing method has been utilized in the process of construction of an underwater tunnel in Singapore. The soil was improved by this method to prevent undesirable heaving of the soil below the excavated area. Quality control experiments approved the effectiveness of CDM method in increasing the strength of the soil and prevention of undesired heave of the ground. The process of the construction of this project and the quality control experiments results are discussed in this paper.INTRODUCTIONThe Marina Coastal Expressway is a 5.3 km long underwater highway tunnel with five lanes in each direction. It mostly comprises a twin box culvert structure (53.3 m exterior width and 10.89 m height) and was opened by the Land Transport Authority of Singapore (LTA).The contract zone C485 was the most challenging area of the construction; it involved a 700 m long underwater tunnel of which 400 m was built beneath the seabed at the mouth of the Singapore River. A double steel pipe sheet pile wall was built as a temporary cofferdam to keep water out of the excavation site, and the cut-and-cover method was used for excavation. In order to ensure a sufficient cross-sectional area for the flow of the Singapore River, the construction was divided into two phases focused on the left bank (Stage 1) and right bank (Stage 2).The Cement Deep Mixing (CDM) method was used to improve the ground, which comprised soft marine clay, to ensure safety during the excavation. The efficiency of this method in increasing the soil’s strength was approved previously. The design standard strength was quck = 800 kPa. Based on the study conducted after the construction, the average the Unconfined Compression Strength (UCS) of the soil stabilized by the CDM method was quf =3,000 kPa. This paper discusses the effect of the CDM soil improvement construction on the reduced displacement from the excavation and the quality control of the soil improvement."

Jan 1, 2015

By Jorj O. Osterberg

The practice of using side shear resistance in the design of drilled shafts socketed in rock is discussed. In the absence of field test data for the particular rock involved, the designer often neglects the side shear altogether or uses an extremely conservative value. The uncertainty of using strength data from compression tests on rock cores is discussed. Examples of full scale load tests are given which illustrate that even in the weakest of rocks, considerable side shear resistances are obtained, enabeling reductions in the depths of the sockets and consequent savings. Existing Practice. The existing design practice in using side friction/bond between a drilled shaft in rock or hard soil varies very considerably in different areas of the U.S., in different areas of the world, among different Geotechnical Engineers, and in the requirements of different building codes. In fact, the variation is so great that it is inconsistent and contradictory. For example, in Florida where fairly weak coral limestone and sandstone is prevalent, the general practice is to use side friction only and to allow no end bearing. In Chicago, Detroit, Boston and other areas where soft clay overlies stiffer clays, hardpan and limestone or other hard rock, the common practice is to allow for no friction and to use end bearing only, even though the lower portion of a shaft frequently penetrates stiff to hard clays and hardpan (glacial till) before bearing on hardpan or rock. In Hong Kong, if the hole is stabilized with drilling mud, no end bearing is allowed. In Boston (Thompson, Erikson, and Smith, 1989), two tests at two sites on 18 inch pipe piles penetrating 100 feet of soft clay and driven only inches into an argillite, tested 140 and 210 tons in ultimate side shear resistance. Certainly, with long drilled shafts, no matter how soft or weak the soil or rock is, some if not considerable side friction occurs, and where drilling mud is used, there must be considerable end bearing.

Jan 1, 1991

By Craig M. Shillaber

On any given day, a simple check of the news will turn up stories related to sustainability, resiliency, climate, or human or natural disaster. In recent years, the winter power grid failure in Texas, the Surfside Condo collapse, unsafe drinking water in Flint, Michi- gan, the Oroville Dam spillway failure, wildfires and flooding (to name a few) have appeared in the U.S. news cycle. As a result, young people are aware of the problems and challenges facing the nation and the world and want to be part of creating sustainable solutions for society. Many choose to major in civil engineering because of a desire to make a difference, address climate change, and develop sustainable and resilient infrastructure for the future. Sustainability is at the core of modern civil engineering practice. In its Policy Statement 418, the American Society of Civil Engineers (ASCE) explains sustainability is a set of conditions where human society can indefinitely keep and enhance quality of life without deteriorating economic, environmental and social resources. Sustainability is an integral part of the technical outcomes identified in the ASCE Body of Knowledge and features prominently in the ethical responsi- bilities of engineers based on the latest version of the ASCE Code of Ethics. Thus, to prepare graduates for successful and ethical engineering practice, civil engineering programs must provide instruction in how to account for social, environmental and economic con- straints in design. Since the deep foundations industry is integral to the broader civil engineering and construc- tion fields and is responsible for supporting critical infrastructure on which human society depends, sustainability should be a key con- sideration in foundations projects. Given the importance of sustainability within civil, geotechnical and foundation engineering, it is worthwhile for the deep foundations industry to consider where and how engineers are trained in sustainability topics through higher education at the undergraduate and graduate level, and what is driving sustainability content in civil and geotechnical engineering curricula.

Nov 1, 2022

By Gregory A. Stephan

A case history of design, prediction, instrumented static load tests on probe piles, installation monitoring, and integrity testing of production piles is presented. Based upon project-specific subsoil conditions, as obtained from several 60 to 80 ft (18.3 to 24.4 m) deep test borings, deep foundation system alternatives included driven concrete and steel pipe piles as well as augered cast-in-place (ACIP) piles. High structural loads, site-specific constraints, and the production time frame mandated by the project owner led to the selection of an ACIP pile foundation system that was designed for a pile capacity of 75 tons (667 kN) in compression and 35 tons (309 kN) in tension. Site-specific concerns were raised about the highly porous nature of fragmented and decomposed sandy limestone as well as the high grout intake during construction that could result in increased foundation cost as well as interconnecting of the piles in the rock layer. Consequentially, a multi-phase ACIP pile evaluation program consisting of instrumented compression pile load tests, in conjunction with single-hole ultrasonic pile testing, pile echo testing (sonic testing), as well as full-time production pile monitoring by an experienced geotechnician was specified. As a result of this testing and evaluation program, while grout usage was determined to be within an acceptable range, the instrumented compression load tests yielded data that allowed use of 55 ft (16.8 m) long ACIP piles in lieu of the original plans to use 70 ft (21.3 m) long precast concrete piles. This information was effectively utilized as part of the overall quality control program to install a total of 268, 14 in. (356 mm) diameter ACIP piles within the building footprint to depths of 55 ft (16.8 m) below the pile cut-off elevation as part of the foundation support system. Information recorded during installation included rate of insertion/extraction of the auger, grout pump strokes and pressure, total grout volume, and grout factors, as well as quality and strength of grout. Additionally, many pre-selected installed piles were tested for integrity with a Pile Integrity Sonic Analyzer (PISA) using both sonic and ultrasonic methods. This engineered, monitored, and tested foundation solution provided an effective and quality intensive basis for completion and approval of the foundation work for the building that resulted in cost savings over other foundation alternatives for the owner.

Jan 1, 1999

By H. Cheng

The Bohai Oil Company has applied all together 11 jack-up oil drilling rigs (movable platforms) (1) which can be classified in terms of their forms of foundations into two types: the integ­ral mat and the column legged, as demonstrated in figure 1. Figure 1 a) indicates the entire structure of the sunk cushion type, i.e. the one with a box-like sunk cushion serving as its foundation by directly sitting on the sea bed. The length, width and height of the outer sides for the sunk cushion stand at 45.8 x 38.0 x 3.3m ( for Rig Bohai No.2 ) and 50.6 x 33.2 x 4.88m ( for Rig Bohai No.6 ), the relative areas of theirs being 1475m2 and 2008m2 respectively and both bigger than the plane areas of the rigs. With a view to realize a convenient drainage of mud while sinking, two holes of 14 x 14m and 32 x 18m in size are constructed in the center part of the sunk cushion. When work sets off, the underside of the sunk cushion operates as a foundation, the sunk cushion being connected to the platform by hull columns which transmit the load of the platform down­wards to the sunk cushion that passes it further onto the subgrade. [ ] Column legs for rigs may also be grouped into two categories considering their features: columns with and without boots. The bodies of boot columns are made up of trusses, whose bottoms, are boot-shaped with a big diameter. The diameter of boot columns of the rigs applied by the Bohai Oil Company shows bigger and it may reach 12 or 18m. In the boot columns, the transmission of the platform's weight into soil is done by the underside areas of boots. While in the case of the vertical columns, which are of cylinder columns of steel with sealed bottom ends shaped inverted arch, the entire drilling platform is supported by the carrying force delivered by the bottoms of these steel cylinders and the frictional force rendered by their outside walls. Such a type of columns is featured by a small diameter, 3m in general. Figure 2 exhibits the schematic diagram of sections regarding the two types of column legs.

Jan 1, 2010

By Khamis Y. Haramy

Curing temperature, density, and moisture significantly affect the velocity measured in the crosshole sonic logging, the rate of strength gain, and the final strength of concrete in drilled shafts and, thereby, affect their structure capacities. Non-destructive field measurements can enhance the QA/QC program by measuring temperature, density, moisture, and sonic velocity of curing concrete during the construction and curing of drilled shafts. The curing environment can greatly affect the concrete strength, and requires close attention during construction. This article shares the experience with the NDE technology used in the QA/QC program in the drilled shaft construction. To understand the mechanism by which a drilled shaft cures under field conditions, two newly constructed drilled shafts were monitored for up to seven days, immediately following concrete placement using the following geophysical logging methods: a) temperature logging; b) crosshole sonic logging; c) gamma-gamma density logging; and d) neutron-moisture logging. One additional drilled shaft was also monitored to a shorter duration. Temperatures were monitored using the sensor in access tubes and/or thermocouples embedded at the center of a drilled shaft and near its reinforcing cage. For a small shaft under 1m diameter, curing temperatures appeared to peak at 41° ? 68° C at different depths at around 24-hour curing time and decreased to and stabilized at around 23° ? 35° C in 6 days. The shaft curing rate varied with depth, shaft diameter, surrounding geo-material types, and the depth of ground water. CSL logging was performed in one shaft from top to bottom from six access tubes and limited monitoring in another shaft. The velocity increased with curing time till 4 to 7 days, and, at a specific time, the velocity appeared to be inversely correlated to curing temperatures. The gamma-gamma density log (GDL) results from 5 different depths were obtained at a source-detector separation of 355 mm. The average density was found to increase with curing time, but decrease slightly in 3 to 5 days. At a given time the GDL density curves seemed to correlate with the neutron monitoring logging (NML) moisture curve. The NML moisture was monitored from 1st to 6th day after concrete placement. The moisture was highest when surrounded by bedrock, then clay, and sand due to different hydration rates.

Jan 1, 2007

By Ronald E. Walkington

The U.S. Department of Energy (DOE) is building the world's newest accelerator-based, pulsed-neutron system, called Spallation Neutron Source (SNS). The facility, located in Oak Ridge, Tennessee, is a partnership of six DOE national laboratories - Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. Oak Ridge has the responsibility for managing the partnership and ultimately operating SNS. SNS will provide opportunities for up to 2,000 researchers each year from universities, national laboratories and industry from around the world for basic and applied research and technology development in the fields of materials science, magnetic materials, polymers and complex fluids, chemistry and biology. When completed, this state-of-the-art research facility will provide neutron beams that are 12 times more intense than any other such source in the world. Most of the world's neutron sources were built decades ago. Therefore, it is easy to understand how SNS will provide new research opportunities unavailable elsewhere, and at the same time restore United States leadership in neutron sciences. Neutron scattering research provides valuable information about materials that cannot be obtained through microscopy, X-rays, spectroscopes, or other techniques. The information gained from neutron scattering research leads to improved materials that are used in high-temperature superconductors, powerful lightweight magnets, aluminum bridge decks, jet aircraft, compact and computer discs, magnetic recording tapes, shatter-proof windshields, and many other applications. SNS is like a flashing strobe light providing high-speed illumination of an object and will record the structure of physical and biological materials from plastics to proteins. Because neutrons have no charge, they can penetrate more deeply into materials than do X-rays, light, or electrons and thus reveal bulk structure and properties of materials. SNS will help to understand and "engineer" better materials and the manufacture of better products at the atomic level. Our high-technology society demands new materials that are stronger, lighter, and cheaper yet perform well under severe conditions. SNS, which is designed with the future in mind, will be the leading neutron research facility for many years to come.

Jan 1, 2001

By KeerthiRaaj Subrmanian, Muthukkumaran Kasinathan

"A railway embankment is under construction between Nagapattinam to Thiruthuraipoondi covering 36.5 km. The sub-soil strata comprises of soft clay extending up to 10 m below existing ground level, which is subjected to stability and settlement problems. A trial stretch covering about 5 kilometer was improved using Prefabricated Vertical Drains (PVD) with surcharge was recommended to accelerate the consolidation settlement. The geotechnical characteristics of the subsoil are examined through laboratory tests on representative soil samples. Recent improvement in the finite element analysis has facilitated modeling of PVD in finite element software for computing the settlement magnitude and time rate of consolidation. In this study the theoretically predicted settlement magnitude and time rate of consolidation from Terzaghi.s vertical consolidation, Barron's radial consolidation are compared with the analyzed FEM results for both the cases with and without PVD improved embankment. The comparative analysis between FEM and predicted data hold good for stresses and the associated deformations. The excess pore water pressure was significantly lower and their dissipation was faster in case of embankment with vertical drains. Thus PLAXIS 2D tool shows fairly convincing results in comparison to the theoretical solutions.1. INTRODUCTIONFrom the earlier times civilization has been developed in a fashion either at the banks of river or near to the shore region, because of the easier availability of food and water. This over centuries made them as huge cities, consequently population rise made the increased necessity of highway, railways, port and even more ground for construction. As a stake researchers are pushed to make a low bearing ground into a massive carrier of skyscrapers, embankment, bridges etc. These low bearing ground suffers from total and differential settlement, slope instability. Hence, numerous ground improvement techniques were followed to eradicate these concerns which include preloading, piling, stone column, vertical drains and geosynthetic reinforcement. Among them Prefabricated vertical drain (PVD) are often used to accelerate consolidation of soft subsoil and has been the main soil improvement method used in improving the soft marine clay deposit (Chu et al.(2004); Chai (2001) and Arulrajah et al.(2003)). Literature review of embankment over soft clay deposit reveals that combination of PVD with preloading is widely considered as an economical and less time consuming ground improvement technique."

Jan 1, 2015

By Morris J. D, Baldwin Z., Wiltcher P. M

21 Moorfields is an oversite development in central London spanning Moorgate tube station. It required the installation of both the highest loaded bearing piles and the highest top loaded static pile test ever undertaken in the UK, at 50.5MN (5,680 tons). The 17-storey building is founded on only 15 large diameter bored piles installed through the roof of the live station. The piles are located in two parallel rows 50 m (164 ft) apart, bridging the underlying train lines and the Crossrail tunnel below. This unique project required a diverse cross-section of skills and experience from the Project Team as we not only pushed the boundaries of design but also those of construction practices. Our team therefore needed to be made up of members from multiple businesses and disciplines. The team worked together, in a highly collaborative environment, for around two years before any work started on site. A key challenge for this project was that there was only one opportunity to construct each pile. If a position had to be abandoned there were no alternative locations and the impact on the project would have been catastrophic. It was therefore vital that all events that may have led to the abandonment of a pile were investigated ahead of commencement on site. Risk elimination and mitigation strategies were developed for all eventualities whether they be associated with the design or construction processes. The successful pile load test, coupled with all contract piles being fully instrumented with state-of-theart fiber optic (CemOptic) cable along their full length, has improved our understanding of the performance of such large and heavily loaded piles. The works piles will all be monitored during the construction of the new building, providing new insight into their real-world performance. Such groundbreaking work has never been undertaken before in the UK and has the potential to significantly influence the industry’s understanding of pile behavior, and design, in the future. This paper will discuss the challenges the team encountered during the design and construction of this highly complex urban project, particularly when adopting, by necessity, a pioneering approach.

By Arash Khosravifar

One of our research thrusts at Portland State University (PSU) centers on developing design guidelines for pile foundations in liquefiable, laterally spreading grounds. This research has been primarily sponsored by the DFI Committee Project Fund (CPF) program through four awards, totaling nearly $240,000 in financial support. DFI contributed half of this financial support, while the other half was contributed in-kind by PSU and DFI Project Advisory Board members. Leveraging the CPF funds, we secured an additional $550,000 in financial support from the National Science. Foundation (NSF), which has enabled our research group to continue exploring this topic and contributing to the broader engineering community's understanding of the behavior of pile foundations in liquefiable soils. The CPF funds have fostered collaborations with practitioners and researchers beyond PSU. Notable examples include collaborative research involving data from five large-scale centrifuge tests on pile-supported wharves by Steve Dickenson, Ph.D., New Albion Geotechnical; Nason McCullough, Ph.D., Jacobs Engineering and Scott Schlechter, Geotechnical Resources, as well as 1-g shake table tests of bridge pile shafts conducted by Professors Ahmed Elgamal, Ph.D., and Ahmed Ebeido, Ph.D., of the University of California, San Diego. In addition to these collaborations, our research has benefited from industry-university partnerships formed through the involvement of DFI Project Advisory Board members. Their support and feedback ensure that our research products are practical and imple- mentable in real-world projects. The impact of the CPF funds extends to supporting graduate students' theses, which were the basis for 17 technical publications. Some of these publications are expected to have a significant impact on the industry. For instance, our 2018 DFI Journal paper, co-authored by former master's student Jonathan Nasr, cur- rently with the Army Corps of Engineers, has been cited in the 2022 British Columbia Supplement to Canadian Highway Bridge Design Code S6:19. A noteworthy product of our study is a step-by-step design procedure for pile- supported wharf structures subjected to the combined effects of lateral spreading and inertial loads, outlined in a 2022 American Society of Civil Engineers' (ASCE) Journal of Geotechnical and Geo- environmental Engineering paper co- authored by former doctoral student Milad Souri, Ph.D., PE, Geotechnical Resources.

Nov 1, 2023