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By Aditya Ayithi, William G. Ryan, Dean Herbst

"For rock socketed drilled shafts, it is a common practice not to include the frictional resistance of overburden soils into the nominal capacity estimation. The primary reason often being cited is “overburden soils resistance is negligible compared to that of rock socket resistance.” However, in certain geological conditions, where the rock layer is located at greater depths, friction resistance from overburden layers can be significant. In addition, at such great depths, shaft drilling becomes very complicated and expensive. In these situations, considering the resistance of the overburden layers can be an economic alternative.This paper presents a case study of an Osterberg cell (O-cell) load test conducted on a 161.8 feet long and 78-inch diameter instrumented test shaft. Based on initial designs, a 72-inch diameter rock socket of lengths 23 and 26 feet was required to provide a LRFD factored friction resistance of 3,200 kips. The load test results revealed that the material in the 72-inch diameter socket does not represent a true rock. However, the test results also proved that the factored friction resistance of overburden layers is greater than the required design resistance. Based on the load test results, it was decided to allow the overburden soils frictional resistance to be considered in the shaft design, resulting in significant economic savings.INTRODUCTIONRock socketed drill shaft design guidelines of various State Department of Transportation (DOTs) agencies allow friction and/or end bearing resistance of only the rock socket portion into the design capacity estimation. It is typical to neglect the frictional resistance of overburden soils. However, in certain geological conditions where the rock layer is at greater depths, friction resistance of the overburden soils can be significant. In this case the friction resistance of overburden soils was verified via the specified instrumented O-cell test program and then used as part of the design capacity.PROJECT DESCRIPTIONAs part of I-29 improvement project, Iowa Department of Transportation (Iowa DOT) planned to replace the dual four lane bridges that cross the Floyd River in Sioux City, Iowa with dual six lane bridges (Fig. 1). Expected benefits from this improvement include improved safety, traffic operations and roadway infrastructure conditions.BRIDGE SUBSTRUCTUREThe project consists of two individual bridges; a new south bound bridge and a new north bound bridge. The south bound bridge is 646-ft long and the north bound bridge is 644-ft long. Both are six-span, pretensioned and pre-stressed concrete beam bridges of varying width. Bridge foundations were designed such that the abutments of both bridges will be supported on driven steel piles and the bridge piers will be on drilled shaft foundations."

Jan 1, 2016

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages.With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages. With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Padmavathi V, M. Najamuddin, M. R. Madhav

Granular piles are one of the leading ground improvement techniques, adopted for the betterment of bearing capacity and reduction in settlements of the foundations and also to accelerate consolidation of the surrounding soil. In the recent past, there has been extensive research on the settlement analysis and behavior of granular piles under varied soil conditions. The application of these theoretical solutions to practical problems requires a knowledge of representative values of the deformation parameters of the ground and the granular piles. However, very little information is available on these parameters. The paper presents a new method for the estimation of the modular ratio of granular piles and modulus of deformation of the surrounding in-situ soil from the compression load tests. The load - settlement response obtained from the compression test results are used in the back analysis for estimating the modulus of deformation of the ground. The presence of granular bed, under the rigid plate for load testing, has been given due consideration in quantifying the proportion of load transferred on to the stone column. Based on these considerations a new method is developed to estimate the modulus of deformation of the ground and the modular ratio of the granular pile.

Sep 1, 2022

By Vijayakumar Viramuthu, Martin Heinrich

Tower of Lot L, L1 & M, Kuala Lumpur City Centre when completed would stand 700 m tall. This Mega tall Skyscraper would merely be less than 500 m away from the world tallest Twin Tower, the Petronas Twin Tower. From June 2018 to February 2020 BAUER (MALAYSIA) SDN. BHD. constructed 225 nos bored piles with diameters of 2.0 m and 2.5 m for this tower. To comply with the depth requirement of the initial design and the need to have the pile toe 2.0 m above competent bedrock, the drilling equipment was required to be able to achieve a maximum drilling depth of 150 m. Actual piles constructed on site were deeper than 120 m. These dimensions caused superlative challenges which included but were not limited to controlling the open borehole stability over time with polymer, installing 70 t heavy steel cages and pouring up to 550 m³ concrete continuously in conjunction with installation of 88 t heavy kingposts into workable fresh concrete. The piling works were executed with one BAUER BG 48 and one BG 72, the biggest drilling rig globally available.

May 1, 2022

By Kiyotaka Ohno, Nobushige Yasuoka, Yosuke Hioki

"The diameter of improved columns adopted by the original DJM Method had been 1000 mm, however, in order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter expanded to 1300 mm was developed between 1998 and 2001 and has been widely applied since then. From the first application of EX-DJM in January 2002 for a first construction project, the total volume of improved soil has reached 325,000 m3 in 17 projects up to September 2014. Because of the advantages of the EX-DJM such as reduction of construction costs and periods leading to reduction in the number of improved columns, adoption of this method is expected to increase in the future. This paper describes the advantages of the EX-DJM, its construction results and case examples including those applied to restoration projects after the Great East Japan Earthquake, 2011.1. BACKGROUND OF DEVELOPMENTThe Dry Jet Mixing (DJM) Method is a soil stabilization method in which a powdery or granular binder is pneumatically fed into and mixed with soft soil to induce chemical reactions that stabilize and strengthen the soil. It was developed by government - private collaboration in Japan between 1977 and 1979. Up to March 2014, the total volume of soil improved by DJM method reached 33,500,000 m3. The initial diameter of improved columns of the original DJM Method was 1000 mm. In order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter 1300 mm was developed between 1998 and 2001.2. ADVANTAGES OF EX-DJMThe construction equipment for the EX-DJM consists of two major parts, which are DJM machine and binder plant are shown in Fig. 1.The construction machine is of double mixing-shaft type with its column diameter expanded to 1200mm or 1300mm. In association with the increase in the column diameter, the binder feeder has also increased its discharge rate by approximately 1.69 times. Same as the increase rate of the area of original diameter 1000mm to diameter 1300mm are shown in Fig. 4."

Jan 1, 2015

By Emilie Lapointe, Fernando Famania

"A reliable determination of the in-placed cement factor, as defined by mass of cement over volume of final element of treated soil, allows the optimization of cement usage to achieve treated soil requirements. Cement determination tests were performed on soil-cement samples, both fresh (as per ASTM D5982) and hardened (as per ASTM C1084). This paper reviews the calibration work required for the D5982 determination of cement content by the heat of hydration method used on soil-cement samples obtained by wet-grabbing. Using the correlation curves in the field provides a rapid assessment of cement content hence optimizing the cement injection rate to match laboratory tests previously conducted. Cement determination tests on hardened soil-cement specimens from wet-grabs and cores were performed using the oxides method. Samples, both cored and wet-grabbed, were tested in a given cement-treated element, and in different soils to inform on the expected variation in cement content from field installation. Results indicate that both cement determination methods are valid for forensically determining cement contents and that they provide better assessment than the conventional field reporting methods. The methods can be used to optimise the cement usage as well as for Quality Assurance, especially when coring quality is poor.INTRODUCTIONThe degree of improvement, and inherent strength, which is attained in a deep-mixed soil is a function of many factors. The binder type, the existing soil, the mixing conditions and the curing conditions are the categories of factors influencing the strength of a given cement-treated soil as agreed by the deep mixing community and as summarized by the Coastal Development of Technology [CDIT] (2012). Given a site with existing soils and conditions requiring soil improvement using a given binder, the designer and/or contractor can control the mixing conditions. Mixing conditions are inclusive of the degree of mixing, mixing duration and the quantity of binder. Once a deep mixing method has been chosen to mix optimally the in-situ soil, the quantity of binder is the only remaining factor to be optimized. The quantity of binder, in the construction industry is commonly referred to as the field binder factor [ar] and defined by the mass of binder over the volume of soil treated with kg/m3 as unit. In research, the quantity of binder is referred to as the binder content [Cc] and expressed as a ratio of the mass of binder over the mass of dry soil mixed."

Jan 1, 2015

By Michael Gebman, Jack Gerwick

"With the opening of the new San Francisco-Oakland Bay Bridge East Span, the former bridge and its caisson foundations are being demolished. Caisson foundations are in the path of a future shipping channel and therefore need removal down to the mudline 50 ft below water (MLLW). For the first caisson to be removed (E3) a mechanical demolition was performed above the waterline and an implosion was done for the remaining caisson down to mudline. Mechanical demolition consisted of excavators operating from either on top of the caisson, from work platforms or from barges. The demolition was implemented on a trial basis with a successful implosion on November 14, 2015. The work was conducted in an environmentally sensitive area, with measures taken to protect fish, marine mammals and birds. This demolition technique was cost effective, faster to execute, and had a better environmental impact then an alternative option. The demolition, measures implemented to protect the environment, outcome, and lessons learned are presented.INTRODUCTIONThe California Department of Transportation needed a cost effective and environmentally friendly solution for removal of the remaining San Francisco-Oakland Bay Bridge (former East Span) caisson foundations, starting with caisson E3. This was necessary to clear a future shipping channel. One option was to construct a steel cofferdam around the caisson to allow demolition in the dry down to the mudline. This option would take years to complete, be cost prohibitive, and its noise would disrupt aquatic life and birds throughout the cofferdam construction and demolition. An alternative option was implemented on a trial basis to conduct a mechanical demolition of the caisson above waterline along with an implosion of the remaining caisson down to mudline. This had the clear advantage as a cofferdam was not needed, and the demolition project duration would be approximately 6 months, instead of several years for the cofferdam option. The potential impact on aquatic life and birds from the implosion was a concern, as the location is environmentally sensitive; however, measures were implemented to minimize these impacts. As presented in this paper, this demolition option was implemented on a trial basis for Caisson E3. The technique succeeded and will now be used on the remaining caissons.BACKGROUND INFO ON CAISSON E3The reinforced concrete Caisson E3 is the largest caisson which supported the former East Span of the Bay Bridge. It was constructed in 1934, with the Bay Bridge opening in 1936. Figure 1 shows the project location. The caisson had a cell arrangement of 7 x 2 above the mudline. Below mudline, the caisson had a cell arrangement of 9 x 4. A structural transition was made between the 7 x 2 and 9 x 4 cell arrangements with buttress walls. All cells were flooded, as underwater openings were included in the original caisson walls to equalize the hydrostatic pressure. Figure 2 shows the caisson layout with limits for mechanical demolition and for the implosion."

Jan 1, 2016

By Graeme Smart, Thomas Fiala

"Yorkville Plaza II, a 40-storey signature condominium residence, is scheduled to open on Avenue Road in Toronto’s prestigious Bloor-Yorkville neighbourhood in spring 2017. In close proximity to Toronto’s subway system, the new tower requires six levels of underground parking, founded in wet, silty sand.Isherwood Geostructural Engineers (Isherwood) was retained in April 2012 by developer Camrost-Felcorp to provide a shoring and excavation solution to address the challenging site conditions. A 31-storey upscale residential building under renovation with three levels of parking, owned by Camrost-Felcorp, flanks the site on the north. Situated on the eastern border is a 7-storey building with three levels of parking. Avenue Road, a four-lane arterial road that brings heavy commuter traffic into downtown Toronto, runs along the western border, and on the southern border of the site is a busy City road that brings traffic into the popular Yorkville area. The tunnel for the Toronto Transit Commission’s (TTC) overburdened east-west subway is located 14.5 m to the south, running below an existing 26-storey neighbouring building. Electrical and communication utilities (Bell) are closely located along the southern side. Non-documented existing excavation shoring, installed in the early 1970s, on the southern and western sides compounded the difficulties presented by the TTC tunnel.This paper presents the unique, non-conventional hybrid shoring solutions Isherwood developed to address the challenges presented by the site, as well as other complications that surfaced during the project: non-encroachment requirements (no tiebacks) beneath uncooperative neighbours, tight geometry to install shoring, and Toronto’s two coldest winters in decades.THE PROJECTBecause of circumstances associated with this site, for this project Isherwood designed two unique shoring walls which drew on their experience and expertise they had gained over the last 40 years. The following is the story of this site:Yorkville is an affluent neighbourhood in the heart of Toronto with a vibrant mix of high-rise towers, residential homes, tony restaurants and flagship shops. The development requires six levels of underground parking (a 20m deep excavation), with three levels undermining the high-rise buildings to the north and east and extending into wet, silty sand.Isherwood was retained in the spring of 2012 to design the excavation shoring. Isherwood’s scope also included field support, design, verification and monitoring. Finite Element Analysis was employed to confirm Isherwood’s design and anticipated movement of the south shoring wall and the TTC subway tunnel.The existing site was severed in two, with the proposed condominium tower slated for the southern portion. On the north half of the site stands a 31-storey building (Yorkville Plaza I at 21 Avenue Road), with three levels of underground parking, sitting on belled caissons which were one foot from the back of the proposed shoring wall so this would have to be considered in relation to the design and drilling methods. Constructed in the early 1970s, Yorkville Plaza I is currently being converted from the Four Seasons hotel to luxury condominiums by Camrost-Felcorp. To the east, directly adjacent to the proposed shoring, stands a 7-storey building (164 Cumberland Road) with three levels of parking, supported on spread footings founded on stiff clayey silt. The tunnel for the TTC’s busy east-west subway, a double box structure built by cut-and-cover in the 1960s, is located 14.5 m to the south, 9 m below grade, and running below an existing 26-storey building. Bell fibre optic communication cables and electrical lines, along with storm and sanitary sewers, are situated on the south and west sides of the site, leaving limited room to install shoring. Due to the heavy volume of commuter traffic on the four-lane arterial road (Avenue Road) to the west, site access and lane closure were not permitted here."

Jan 1, 2015

By Gang Guo, Zhong Liu

"In response to an increasing demand of anchored structures for underground space and transportation infrastructure in China, an innovative underreamed ground anchorage system was created. The novel anchorage system has provided more efficient functions with higher capacity at lower cost, because of the enlarged cylindrical body (known as ECB) sealed in capsule at bottom of anchorage. This paper presents the detailed structure of innovative anchorage system and its special features. To investigate the bearing mechanism of new anchorage, we evaluate its performance and failure mode based on the experimental results, and also indicate its strain-hardening load-displacement relationship. Unlike the shaft anchorages, it is identified no overall failure to be found in soil surrounding the underreamed anchorage. More importantly, the anchorage capacity is governed by the base resistance, which takes more than 80% of total pullout capacity resulting from the contribution of ECB. Finally a case history of anti-floating project introduces the new combined construction approach and procedure, which has provided the contribution to the quality control and cost efficiency.INTRODUCTION AND BACKGROUNDThe construction boom over two decades in China has resulted in an increasing demand for underground space and slope stability. The infrastructures market requires the more efficient anchorage systems for retaining structures, resisting uplift forces and slope protection. The major concern focuses on gaining higher capacity and lower cost resulted from perfecting anchorage systems. There are three main anchorage systems designed to achieve the above objectives: ? single bore multiple anchorage system (Barley 1997), ? regroutable anchorage system (Smoltczyk 1991), ? underreamed anchorage systems (Xanthakos 1991). Generally, the concept ? comparing with the other two, can be more competitive due to its distinct advantages. To improve the performance and durability of ground anchorages under the complex geological conditions and diversified engineering requirements, a number of different underreamed anchorage technologies had been used, which included cone - shape anchorage described by Liao, Wu and Shu (1997) in Taiwan, Soilex anchorage developed in Sweden (Massarsch et al. 1997), Soletanche anchorage proposed in France, blasting anchorage used in Czechoslovakia (Hobst and Zajic 1986), jet-grouting anchorage innovated in Europe (Anon 1988), as well as deep mixing anchorage created in Japan (Cheng et al. 2000).The underreamed anchorage systems have the remarkable advantages compared to the shaft anchorage system. However, there are also some weaknesses inherent in the underreamed systems. For instance, the mechanical underreamed anchorage is unsuitable in sand or waterbearing ground, because the enlarged hole is easy to collapse, and it is hard to ensure the quality of anchorages. On the other hand, relying on the blasting in deep hole, the geometrical space and dimension of enlarged hole is uncontrollable, meanwhile, the continuous blasting operations may easily cause the serious ground deformation and the negative effects to the completed anchorages."

Jan 1, 1900

By Maurice Guillaud

The most striking innovations on diaphragm-wall construction plant are those associated with continuous real-time trajectory monitoring of the excavating tool (either a grab or a hydro-cutter). The recent equipments are fitted with clinometers and gyrometers to control deflection, rotation or deviation from the vertical, thus allowing to install diaphragm-walls with a verticality accuracy of less than 0.3%. One of the greatest advantages of extensive use of on-board IT systems on the Hydrocutters and hydraulic grab machines is that it aids quality control by automatically producing complete real-time reports of all excavating data (verticality, depth, type of ground, rate of progress, stoppages, etc.). These reports are available to the Engineer, providing the total transparency required for Works Supervision and the Quality Assurance Plan. They also provide the Contractor with input data for databases used for optimising efficiency and progress criteria on future jobs.

Jan 1, 2002

By Marc Raithel, Sven Schröer, Lilma Schimmel, Dimiter Alexiew

"The Geotextile Encased Columns (GEC) deep foundation system for embankments and dikes on soft soils was introduced some 20 years ago and is now considered State-of-the-art in Germany, Europe and, step by step, worldwide. The GECs consist of compacted non-cohesive granular fill similar e.g. to common gravel columns with one decisive difference: they are confined in a high-strength, high-modulus, flexible geotextile “cylinder” (encasement). This engineered element with parameters being adaptable in a wide range provides a decisive tool to control and optimize the behavior of the GEC foundation system. Consequently, the GECs work properly even in extremely soft soils, and a wide range of fills inclusive of sands can be used. In the meantime vast design and technological experience is available and codified design methods exist. Initially the paper briefly describes the general idea, the basics and specifics of design, construction technology, materials, restrictions and optimal application areas. Then it focuses on three informative case studies. They are briefly presented focusing for brevity only on the most important facts and experience inclusive of the most meaningful data of short- and long-term measurement programs.INTRODUCTIONWhen considering embankments on soft soils, generally two groups of solutions exist:Unsupported embankments; there are four main options:a) build up embankment extremely slowly waiting for sufficient consolidation after every stage;b) replace the soft soil partially or totally;c) install a high-strength basal reinforcement providing overall and local stability and allowing much faster embankment construction;d) combine c) with strip drains to accelerate consolidation and thus the construction process additionally (Fig. 1, left).Today, practically only option ""d"" is of practical relevance. Despite all the pros and cons, the common attribute of all non-supported options is that local and overall stability (Ultimate Limit State-ULS) can be achieved and controlled, but not the short- and long-term settlements (Serviceability Limit State-SLS). The latter can be significant, e.g. up to 30% of the nominal planned embankment height. Supported embankments (Fig. 1, right): the main common idea is to over-bridge the soft soil layers by supporting vertical elements of different types: rigid piles, trench walls etc. or by ""softer"" solutions of different column types (compacted, cemented, mixed-in-place etc.). Herein the borderlines between “piles”, ""pile-similar elements"" and ""soil improvement” are fluent and depend on country, traditions, codes etc. The common attribute of the “supported” schemes is a minimized settlement. Twenty years ago a new specific solution was launched: the Geotextile Encased Columns (GEC), which is discussed in more detail below."

Jan 1, 2017

By Nozomu Kotake, Rakshya Shrestha, Ralph Griffin, Stefanos Papadopulos, Jeff Fippin, Sushil Kafle

Direct Power Compaction (DPC) is a deep Vibro-compaction method used for liquefaction mitigation. In DPC, H-beams are used as vibrating rods penetrating deep into the ground, and a vibrating force is applied directly to the tip of these H-beams to densify the loose ground. A characteristic feature of DPC is the use of a flapping plate installed at the base of the H-beam to enhance the compaction efficiency during penetration. In addition, 2-rod and 4-rod type equipment have been developed to improve productivity and enable rapid construction. DPC was selected as the most suitable and cost-effective technique to mitigate liquefaction hazards in two projects in the San Francisco Bay Area, one on Alameda Island and another on Treasure Island. Both sites were capped with hydraulically placed sand fills. Liquefaction analyses indicated excessive liquefaction-induced settlements and large lateral spread without ground improvement. Densification using DPC was performed up to depths of 42 ft to reduce the liquefaction potential of the sand fill to acceptable levels and to allow planned improvements. Cone penetration tests were conducted before and after DPC to evaluate its performance. This paper describes the equipment and process involved in DPC and discusses its application in terms of subsurface conditions and geotechnical design considerations.

Sep 8, 2021

By Paul Thurlow, Richard K. Lipscombe

The measurement of deflection of designed diaphragm walls is critical for near real time information to assess wall and soil behaviour as the internal area is excavated in a controlled manner. Data enables the site team and designers to check performance of the design, which is linked to safeguarding the site and the external stakeholders.This paper documents the use of Shape Accel Arrays at the Tottenham Court Road Western Ticket Hall during excavation and propping within the diaphragm wall for the Crossrail project. It shows how the data obtained was used within the site settlement management plan to assist in the control of the works and the information used for Value Engineering purposes that benefitted the project.The use of Shape Accel Arrays for measuring the deflection of retaining walls is not commonplace in the UK construction industry, with the Tottenham Court Road Western Ticket Hall being one of the first times they have been used in such a way. A detailed analysis of the data obtained from the instruments has been undertaken, and compared to the results obtained from the manual inclinometers that were read next to the SAAs. The advantages of the relatively new SAAs have been discussed, as well as other applications of the instrument.

Jan 1, 2017

Jan 1, 2003

By P. Kiruthika, A. Murali Krishna

Soil liquefaction is a dangerous phenomenon that involves huge damages during strong earthquake ground motion event. Stone columns (SCs) are widely used as liquefaction mitigation element which is expected to perform the improvements against liquefaction hazard by densifying, increasing the stiffness and rapid dissipation of excess pore water pressure in the surrounding soil. Although in the recent times few studies on the behaviour of stone columns in the seismic zone has evolved, the performance of SCs in the multi-layered soils is not extensively examined. This paper presents the numerical investigations on the performance of SCs installed in the multi-layered soils as a liquefaction mitigation measure against the seismic loading. The acceleration time histories, Excess Porewater Pressure (EPP), vertical displacement and stress ratio evaluated along different depths using PLAXIS 2D. With the installation of stone column there is a considerable reduction in the acceleration amplitude, which in turn reduces the EPP and vertical displacement at different locations and the amplitude of reduction depends on the soil stiffness levels at the depth.

Sep 1, 2022

By Brian J. Olson, Kevin Haiar

Originally constructed between 1939 and 1941 as part of Franklin D. Roosevelt’s New Deal programs, the Bonneville to Hood River 115 kV Transmission Line required an infrastructure upgrade to remain reliable and in-service. The line traverses the rugged landscape of the Columbia River Gorge on the Oregon- Washington border, featuring steep, talus slopes; uneven, rocky terrain; and a variety of environmental sensitivities. This paper details the design and construction of 27 micropile foundations for new, fire- hardening steel poles through a particularly challenging stretch of the alignment. The difficult access and environmental constraints at these sites designated them as helicopter-accessible and precluded the collection of detailed geotechnical information prior to construction. Micropiles provided a viable foundation alternative due to their portability and flexibility during construction. Detail will be provided on the extensive preliminary desktop study performed, as well as the process of developing engineering designs to successfully accommodate for variability and unknowns in complex geological conditions. With an increasing number of electric power projects traversing challenging terrain and facing similar obstacles, this project stands to provide valuable lessons learned to the industry.

Sep 8, 2021

By Dharmil S. Patel, Zoyav S. Benyaminov, Cassandra A. Wetzel

Rehabilitation of the Henry Hudson Bridge is nearing completion, connecting Spuyten Duyvil in the Bronx to Inwood Hill in Manhattan, New York. Constructed in 1936, the Henry Hudson Bridge spans 840 feet over the Hudson River. Challenging geotechnical aspects of this Project required a team of innovators to overcome. Rehabilitation of the existing bridge involved the replacement of sixteen bent pedestal substructures, two abutment pilasters and installation of new deep foundations at the skewbacks. However, the Bridge, roadways, adjacent Metro-North Railroad (MNR) structures and New York City (NYC) Parks land were to remain open to the public for use, with minimal disturbance. In addition to physical constraints, geologic site conditions varied widely across both sides of the River, with varying bedrock quality and depth, greatly impacting the proposed design and construction. Extensive analysis of bedrock conditions was conducted to locate areas of potential wedge failure. The implementation of anchors was used to reinforce rock stability where pedestals and pilasters were replaced. This paper describes several challenging technical and natural aspects overcome in the rehabilitation of the Henry Hudson bridge foundations, including varying geologic site conditions, access restrictions, construction limitations, project specifications and design requirements.

Sep 8, 2021

By Tim Chapman

This general report considers what promoters of deep basement projects want from their teams and whether they get it often enough. Most large projects are based on complex financial models where the funding is related to a future income stream. Project delays and cost over-runs can critically affect the financial model. Too often, delays and cost over-runs originate in the substructure and foundations. We must take positive steps to improve our industry's reputation for reliability.

Jan 1, 2006

By Timothy C. Siegel

This report presents the results of a synthesis on the design and analysis of ground improvement for liquefaction mitigation. The synthesis included an industry survey concerning the practice of ground improvement for liquefaction mitigation. Participation in the survey was solicited by advertisements in several trade magazines and by e-mail for the DFI membership. The survey participants numbered 150. Their professional roles include consulting engineers, specialty contractors, design engineers, government engineers, and academicians. They represent a variety of geographical areas including North/Central/South America, United Kingdom, Middle East, Caribbean, Hawaii, Japan, India, Egypt, France, Australia and New Zealand. Upon completion of the survey, several professionals in the field of liquefaction and ground improvement were interviewed for them to elaborate on the survey results. The interviews are included in the Appendix of this report. Financial support for the project was provided by DFI and Dan Brown and Associates PC. The concept of the liquefaction mitigation synthesis was developed by DFI?s Ground Improvement Committee in recognition that: (a) The results of recent research and post-earthquake reconnaissance have challenged previously longheld beliefs about liquefaction and associated mitigation techniques, and; (b) The DFI membership and the engineering/construction industry are interested to know if and how engineers and designers are subsequently adjusting their practice in consideration of recent research and post-earthquake reconnaissance. For more detailed information on recent research and post-earthquake reconnaissance, presentations are available from the State-of-the-Art Forum: Liquefaction Consequences and Mitigation that was held in St. Louis in 2012. A commentary of the state-of-practice in ground improvement for liquefaction mitigation (prepared by DFI?s Ground Improvement Committee) is included in this issue of the DFI Journal. The author would like to thank the participants of the survey and especially Mr. Mike Jeffries, Dr. Les Youd, and Dr. Ikuo Towhata for their willingness to share their expertise in interviews. The author also acknowledges Mary Ellen Bruce of DFI, Billy Camp of S&ME, Inc., and Marty Taube of DGI Menard (and Chair of DFI?s Ground Improvement Committee) for their signifi cant contributions.

Aug 1, 2013