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By Gianni O. Chieruzzi

A 400 MW, gas-fed power plant on floating piles and piled raft foundations was constructed in the Province of Moskovskaya, Russia in 2008. The subsurface is characterized by fill underlain by loose to medium dense alluvial deposits, with peat and clay interbeds, a stiff to hard, highly plastic, silty clay stratum of glacial origin, and a stratum of very dense, varved interbeds of sand and silt. More than 800, drilled concrete piles were constructed at the site. The pile length ranged from 15 to 23 meters below existing surface grade, and the pile diameter ranged from 0.9 to 1 meter. Initial analyses by others predicted total power plant settlements of 3 to 4 cm when subjected to the permanent loading conditions. Under a peer review process for the equipment supplier, subsurface investigation and testing were performed to verify the consolidation parameters used for foundation design of the power plant foundation. The parameters obtained in this investigation were used in the 3-D finite-element model ELPLA as inputs for the settlement analysis of the turbine building and power island. The ELPA analyses predicted settlements on the order of 7 cm over a period of 30 years. The actual settlements after two years of monitoring were compared against the model predictions. The rate of settlement and the recompression index were both underestimated in our model. The measured settlements have enabled us to calibrate both of these model parameters so that the model better matches the data.

By Alireza Ayoubian, Douglas S. Roy, Gianni O. Chieruzzi

"A 400 MW, gas-fed power plant on floating piles and piled raft foundations was constructed in the Province of Moskovskaya, Russia in 2008. The subsurface is characterized by fill underlain by loose to medium dense alluvial deposits, with peat and clay interbeds, a stiff to hard, highly plastic, silty clay stratum of glacial origin, and a stratum of very dense, varved interbeds of sand and silt.More than 800, drilled concrete piles were constructed at the site. The pile length ranged from 15 to 23 meters below existing surface grade, and the pile diameter ranged from 0.9 to 1 meter.Initial analyses by others predicted total power plant settlements of 3 to 4 cm when subjected to the permanent loading conditions. Under a peer review process for the equipment supplier, subsurface investigation and testing were performed to verify the consolidation parameters used for foundation design of the power plant foundation. The parameters obtained in this investigation were used in the 3-D finite-element model ELPLA as inputs for the settlement analysis of the turbine building and power island. The ELPA analyses predicted settlements on the order of 7 cm over a period of 30 years. The actual settlements after two years of monitoring were compared against the model predictions. The rate of settlement and the recompression index were both underestimated in our model. The measured settlements have enabled us to calibrate both of these model parameters so that the model better matches the data.IntroductionA 400 MW, gas-fed power plant was constructed near Moscow in the Province of Moskovskaya in Russia.Figure 1 shows the general arrangement of the main structures, and the geometry of the piles supporting those structures."

Jan 1, 2017

By Mohab Sabry, Emre Biringen

"Over the past decades, there has been an increasing recognition of the strategic use of pile-supported rafts in design of heavily-loaded structures to reduce total and differential settlements. However, such a hybrid foundation construction method has not been widely utilized in many countries, including the U.S., due to code limitations. In current practice, the foundation design is based on either (i) the bearing capacity of the raft supported by the subgrade soils, or (ii) solely the pile capacity. This paper addresses the potential use of such hybrid piled-raft systems, where the structural load is shared by both by the piles and the subgrade soils directly beneath the raft, in foundation design of power plant structures. The study assessed some of the characteristics of piled-raft behavior by undertaking three-dimensional finite element analyses of two raft sizes, and various pile layout patterns, including the rafts with piles distributed evenly and only in the central area of the raft. The computer software PLAXIS 3D with the Mohr-Coulomb constitutive soil model was used to facilitate the modeling of such cases. The results presented in this paper indicate how strategically locating the piles could reduce the differential and total settlements.INTRODUCTIONUnder the high applied loads coming from the superstructure, the addition of piles is primarily required to improve the factor of safety against failure when a raft does not provide adequate bearing capacity. If the bearing capacity of the raft is sufficient to carry the total load with a reasonable safety margin, then the addition of piles is usually intended to reduce the settlements to an acceptable amount. In current practice, the design process for pile-supported raft foundations conservatively concentrates on providing solely the pile capacity to carry the total structural load without taking the contribution of the raft into account. This paper addresses the potential use of hybrid piled-rafts in controlling foundation settlement of power plant structures by considering the support of both the piles and the subgrade soils beneath the raft to carry the load."

Jan 1, 2017

By Dale Berner, Michael O’Sullivan

"This article focuses on lessons learned from innovative designs including in-the-wet construction methodology and modified foundation conditions, for two United States Army Corps of Engineers (USACE) megaprojects. Olmsted Dam FoundationThe over $2 billion Olmsted Dam on the Ohio River is currently under construction 16 mi (29.6 km) upstream from the confluence with the Mississippi River. The project is under the jurisdiction of the Louisville District of the USACE. It will consist of an 800 ft (244 m) long tainter gate section, a 1,400 ft (427 m) navigable pass, two boat abutment sections, a fixed weir section, and upstream and downstream scour protection. The Olmsted Dam and its two 1,200 ft (366 m) locks, which were built in 2002, will eventually replace both Locks and Dam #52 and #53, both built in 1929, and thereby bring significant benefits to the Ohio River navigation system.In 2002, the Jacobs/COWI JV completed the design of the dam; which was an engineering challenge for several reasons. A significant consideration was its proximity to the New Madrid Fault, which could impose an 8.4 Richter scale seismic event on the structure, which is located in an area of potentially liquefiable alluvium. The extensive seismic analysis performed by the designer included a response spectra analyses, lateral pushover analyses of pile foundations, hydrodynamic added masses, pile group effects, and the development of kinematic motions as a result of the soil-pilestructure interaction."

Jan 1, 2016

By Franz-Werner Gerressen, Manfred Schoepf

"Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm walling in even more complex conditions. Complex and/or challenging conditions in terms of ground conditions have a major impact in regards of choosing the right tools for excavation purpose. Complex conditions in terms of space limitations, especially for inner city job sites, require specifically adapted solutions for slurry, spoil, reinforcement and concrete handling and the related logistic to ensure smooth production. Furthermore, one focus will be given to the QA/QC topics of the production process. Real time installation control, data transfer and reporting systems become more and more important ensuring the five dimensions of a jobsite. Therefore, the paper will describe the construction method and the sequence of activities required for the construction of diaphragm wall systems with the focus on the cutter technology. It will describe also the main equipment which will be needed to execute these works under the various conditions INTRODUCTION Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions. Of course diaphragm wall can also be used as deep groundwater barriers (Cut-Off-Walls). This market has shown that the demand for these types of walls is reaching more and more difficult soil conditions or required depths which are surpassing the current standard. The trench cutter is the most important tool for performing this work. The trench cutter itself is a reverse circulation excavation tool. It consists of a heavy steel frame with two drive gears attached to its bottom end, which rotates in opposite direction around horizontal axis. Cutter wheels are mounted onto the drive gears. As they rotate, the soil beneath the cutter is continuously being broken up, removed, mixed with the bentonite slurry in the trench and moved towards the opening of the pump suction box. The slurry loaded with soil and rock particles is pumped by a centrifugal pump which is located right above the cutter wheels, up through a hose system up to a desanding plant where the slurry is cleaned and returned into the trench."

Jan 1, 2015

By Massimo Poggio, Gabriele Balconi, Andrea M. R. Pettinaroli, Mario Ruggiero, Riccardo Castellanza

Grouting technologies are ground treatment techniques used for modifying the behaviour of a mass of soil or rock by injecting a mixture. The sleeved port pipes (also called Tube A Manchette) are highly diffused for grouting treatment of coarse soils and fissured rocks. This paper describes a combination of jet grouting and rock grouting with MPSP (multiple packer sleeve pipe) technique that has been used to realize waterproof curtains under fluvial structures for a cascade hydro-power plant. This is composed by five mini hydro-power plants, placed along the Iskar River, in Bulgaria, and composed by a penstock followed by the power house, a spillway, and an earth dam containing the reservoir. The geology of the site is characterized by an upper alluvial deposit lying over the bedrock. In each site, similar treatments were carried out: an impervious curtain along the plant section, obtained by executing jet-grouting columns in the surficial alluvial layers and grouting the underlying fractured rock by means of port pipes. The temporary embankment, built during the works for protecting each site from the possible river floods, has been waterproofed and stabilized by reinforced jet-grouting columns. The grouting processes have been controlled and monitored by a computerized system. INTRODUCTION The Iskar river cascade hydropower plant is situated northern of Sofia, Bulgaria, and it is composed by nine plants. Actually five of them have been built and produce energy. Each plant is composed by a penstock followed by the turbine building, a spillway, and an earth dam that contains the reservoir. The Iskar rivers runs in a narrow valley characterized by diorite or diabase rocks, with an upper deposit of alluvial soil, composed mainly by gravel and sand. Each plant requires an impervious curtain under the structures and in correspondence of the earth dam: this has been obtained by means of a jet grouting treatment of the alluvial coarse soil, and a grouting treatment with cement mixtures of the underlying rock using the MPSP technology. During the construction of the structures, the site has been shielded from the river water by a temporary earth embankment that has been statically improved and waterproofed by jet grouting columns reinforced with steel tubes; this allowed to work without interruption even in case of flood of the Iskar river.

Jan 1, 2019

By Walid El Kamash, Sadik Oztoprak

"Soft soil presents a challenge against multistory buildings in some cities of Egypt such as Port Said due to the consolidation settlement. Deep mixed (DM) columns are used to improve the soft foundation soil in order to reduce the total and differential settlements. Latest research revealed that this improvement technique also increases the rate of mechanical consolidation due to column yielding caused by stress concentration from the soft soil. In this study, extended poly-styrene (EPS) Geofoam is used to replace the soft soil over DM columns in order to control the stress concentration and settlement. To understand the effect of EPS geofoam on the degree of consolidation, stress concentration and settlement, a parametric study was carried out through a mechanically and hydraulically-coupled numerical method. A unit cell model is used, in which the soil was considered linear elastic; DM column and EPS Geofoam are elasticplastic materials. Results reveal that EPS geofoam is helpful for reducing the settlements and accelerating the consolidation. Increasing the length of the column of the deep mixed foundation with EPS geofoam has a significant effect on accelerating the consolidation.INTRODUCTIONExpanded polystyrene (EPS) geofoam is a lightweight polymeric material which is made by expansion of raw plastic beads. The expansion of the EPS beads are spherical-shaped particles containing closed hollow cells. EPS which plays an important role as an innovative lightweight construction material is now well recognized due to its low density in addition to high compressive and rupture strength. Inglis (1996) reported the first use of EPS geofoam as a seismic buffer to reduce potential seismic loads against a nonyielding basement wall. Gaskin (2000) and Bathurst et al. (2007) carried out reduced-scale shaking table test on a rigid retaining wall protected by EPS geofoam. The test data showed that the peak lateral loads acting on compressible model walls were reduced below values measured for nominally identical structure but with no compressible inclusion. Abdelrahman and El Kamash (2014) investigated the behavior of EPS Geofoam beneath raft foundation on soft soil of Port Said. They showed the ability of EPS to control vertical displacements. The investigation of the behavior of EPS geofoam with DM column has not attracted more attention of previous researchers. In this paper, the behavior of replacing the soft soil by EPS geofoam was examined in the presence of DM column."

Jan 1, 2015

By Abid Adekunte

"Whilst safety is considered to be of high priority in every aspect of engineering projects, it is equally important for designers and contractors to be continually aware of their obligations to the immediate environment and the society as a whole. These include responsibilities to minimise the amount of nonrenewable natural resources and energy used on projects, to reduce carbon foot prints on projects, to minimise the quantity of wastes produced on projects, to minimise the level of pollution on construction sites and to reuse materials and waste products whenever and wherever possible.In other words, professional engineering practice needs to be accompanied by an underlying fundamental objective to improve, restore and sustain the environment. However, achieving this objective requires continuous collaborative interaction and effective communication between the different specialists involved on every project from the early stages. In addition, developing a well-thought-out economical solution is key to achieving the sustainability aspect of the above objective.This paper focuses on the design, construction and management of a recently completed large multi-level basement scheme in Central London, with greater emphasis on collaborative approaches taken by the design engineers, commercial managers, construction managers and site operatives to deliver the most reasonably economical and sustainable solutions to the client. Solutions were based on combinations of general and specialist engineering knowledge, with due considerations for health & safety, sustainability, cost, practicality, time and community requirements.INTRODUCTIONUnderground structures have become vital components of urban life worldwide e.g. tunnels serve many water, wastewater, highway and railway schemes, basements have been incorporated into many urban commercial, institutional and residential developments, while many public underground car parks have been built to deal with the incessant problem of insufficient surface parking spaces in busy urban centres.The safe design, construction and maintenance of underground structures have been well-mastered by the deep foundation industry over the years. However, just like many other areas of engineering, aside the need to satisfy safety requirements, underground construction practice is now faced with a new set of requirements; the demand for more sustainable and cost-effective solutions, with reduced environmental and societal impacts. Designers and managers of underground construction schemes are now compelled to minimise the use of natural resources and energy, to minimise the amount of waste produced, to minimise the level of environmental pollution, noise and disruption to traffic and normal societal life at ground level around underground construction sites. In addition, the recycling of site wastes and reuse of materials have now become important aspects of underground space development. Considerable effort is being put into promoting sustainable development across the industry."

Jan 1, 2017

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 Amr Sallam, David Thompson, Moataz Hassan

"The Little Lake Harris (LLH) Bridge was constructed in 1951 to replace the eastwest County Road 48 Bridge connecting the towns of Howey-in-the-Hills and Astatula in Lake County, Florida, United States. The 78-span bridge carries two lanes of traffic, is 3,130 feet long, and 36.1 feet wide. The concrete deck is supported by steel I-girders carried by one row of 18-inch square precast concrete driven pile. In the late 1980's, slight settlements were observed in several bents. In 1990, Florida Department of Transportation (FDOT) initiated annual survey of deck elevations during bridge inspections to monitor settlement. Due to the slow nature and magnitude of settlement, substructure instability was not a major concern to the department. However, public concern over the settlement and rough ride of the bridge continued to rise. FDOT contracted Kisinger Campo & Associates Corp. (KCA) to provide the needed design to correct the dips in the riding surface and minimize future settlement. KCA's initial design was based on the concept of ""helper bents"" at the settled bents in order to restore the bridge to original elevation. Estimated construction cost for seven helper bents was about $3.3M. FDOT requested evaluating other alternatives to reduce the cost of the bridge restoration. KCA involved the geotechnical consultant, Terracon Consultants, Inc. (Terracon), to perform a peer review and provide an economical alternative solution. Jacking and shimming the bridge was determined to be both technically viable and economical with a total cost of less than $300K. The design was completed in March 2010 and construction was completed in February 2011. This paper provides an overview of the LLH Bridge history, summarizes the evolution of the design methodology including the findings of the geotechnical study and presents lessons learned during the design and construction of the project.INTRODUCTIONThe Safety and Preservation of the State Highway System is the top priority of the FDOT. Therefore, FDOT initiated a bridge management program that starts with conducting biennial safety inspections performed by Certified Bridge Inspectors (CBI). The inspection reports together with the CBI’s recommendations are reviewed by a registered Professional Engineer (PE) and work orders are issued with priority ranking depending on the severity of the bridge deficiencies. If the scope of work is considered beyond the in-house crews’ capability, the work is then included in a contract for and bid. LLH Bridge was a little different. It was initiated in direct response to number of complaints the FDOT District 5 Structures Maintenance Office (D5SMO) received regarding settlement of the Little Lake Harris Bridge."

Jan 1, 2015

By Steve Davidow, Nick Salisbury

"The Sunrise Powerlink project received numerous industry awards for excellence. The DFI C. William Bermingham Innovation Award recognized the innovative use of prefabricated steel micropile caps to increase safety, accelerate project schedule and minimize the project carbon footprint. DFI’s Outstanding Project Award (OPA) and World Cup of Micropiles Challenge Award honored the project as a whole and its positive outcome and industry example. Sunrise Powerlink involved construction of San Diego Gas and Electric’s (SDG&E’s) new 117 mile (188 km) 500/230 kilovolt transmission line from Imperial County to San Diego County, Calif. The alignment traversed a wide variety of geotechnical conditions, including desert, mountain and marine environments, and many of the 421 lattice tower structures used to carry the transmission lines were located in remote, rugged or environmentally-sensitive terrain.Micropiles were introduced as a solution to foundation construction in these challenging areas, which ultimately involved the design and application of Crux Subsurface Inc.’s patented steel micropile cap at 234 tower locations. This was the inaugural application of the technology, and a significant component to ensuring a successful project outcome. Foundation ChallengesThe alignment crossed a number of protected environments, including National Forest land, critical habitat for bald eagles and Peninsular big horn sheep, and numerous private properties. As a result of the remote, rugged terrain, it was initially determined that 75 lattice tower locations would not permit road construction access and would require helicopter-only construction techniques. A strict in-service date combined with long permitting lead times eventually increased this number to 234 sites. Preconstruction access constraints prohibited site-specific geotechnical sampling, so initial foundation designs were completed using only available seismic geophysical surveying and preliminary mapping data. The combination of these challenges required a foundation alternative that could accommodate variable subsurface conditions, required a minimal environmental footprint for installation, and featured lightweight materials and equipment that could be transported by helicopter."

Jan 1, 2014

By Joseph T. Coe, Siavash Mahvelati, Philip Asabere

Characterization of existing foundations remains an important issue as foundation reuse and rehabilitation continue to garner increased attention. In the case of unknown foundations, geophysical and nondestructive testing (NDT) methods have been utilized in the past to evaluate foundation geometry and could serve as useful tools in the case of foundation reuse. A comprehensive study was initiated in the late 1990’s and early 2000’s that evaluated the effectiveness of the available geophysical and NDT technologies to characterize unknown foundations for scour evaluation purposes. At the time of that study, the Multichannel Analysis of Surface Waves (MASW) geophysical method was in its infancy and not widely used. Since then, MASW has become increasingly prevalent in geotechnical applications as the method presents a number of potential advantages when characterizing the subsurface, including rapid testing, increased signal to noise ratio, and ability to resolve velocity inversions. This paper presents a case study that explores the abilities of MASW as an unknown foundation characterization tool. MASW was applied to determine subsurface stiffness at a bridge foundation site in the Philadelphia metropolitan area. One MASW survey line was performed immediately over the foundation of interest and another was performed over a control zone adjacent to the foundation to establish a baseline site profile. The purpose of this testing was to examine whether MASW could establish the geometry of the foundation at this site. This paper presents the site conditions and MASW testing procedures, followed by a discussion of data analysis and interpretation.

Jan 1, 2016

By Gust Van Lysebetten, Monika de Vos

The objectives of monitoring geotechnical structures can be very diverse, including optimisation of the design, quality control, long term performance assessment, and approval of innovative execution techniques. In this context, new measurement techniques, based on optical fibres, offer the possibility of accurate strain and temperature monitoring with very small sensors and limited numbers of cables. This paper briefly presents optical fibre sensing techniques and illustrates their application to geotechnical structures by means of some projects, carried out by the Belgian Building Research Institute (BBRI).

May 1, 2022

By J. Erik Loehr, Andrew Z. Boeckmann

"Poor drainage is a common cause of poor performance of earth retention systems, resulting in burdensome serviceability problems that can progress to outright failure of the retention system if not addressed. A drainage system consisting of filtered conical drains that can be installed through the face of an existing retaining wall and readily maintained was evaluated through tests of physical and numerical models. The physical models were constructed with different backfill materials in a container measuring 8 ft wide by 4 ft tall by 15 ft long. Tests were conducted by saturating the backfill under a constant water elevation atop the model, and then maintaining the water elevation until seepage from the drains reached a steady state condition. Pore pressures within the backfill and outflow from the drains were measured to facilitate calibration of numerical models that accompany the physical models. Results from the calibrated finite element models were used to develop design criteria for the drains. The design criteria establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain.INTRODUCTIONMany retaining wall performance problems are a result of poor drainage of the wall backfill. Consequences of poorly drained backfill include displacement and rotation of the wall face, including the extreme case of collapse, and seepage through the face of the wall, which is in turn associated with damage from corrosion, dry rot, and other forms of deterioration. A common approach to improve drainage of an existing wall is the installation of drainage features (e.g. “weep holes”) in the face of the retaining wall. Weep holes facilitate controlled seepage through the face, which relieves water pressure within the backfill and directs seepage to known locations in the wall face. Although installation of weep holes is relatively common, engineering methodologies for selecting the size (diameter) and spacing (along the wall) of facial drainage features are uncommon if not altogether non-existent. This paper documents tests of physical and numerical models of retaining walls with facial drainage features, including conventional weep holes as well as maintainable drains installed through the face and extending into the wall backfill. Results of the testing were used to develop generic design criteria, which establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain."

Jan 1, 2016

By Alison Savage, Michael Terry

"For decades, the International Market Place (IMP) has been an icon in the heart of Waikiki in Honolulu, Hawaii. It was famous for Duke Kahanamoku’s restaurant where people flocked to hear Don Ho sing in the ’60s and ’70s. Later, it was a bustling, open-air hub of small vendors who peddled everything from Hawaiian souvenirs and jewelry to food court meals and farmer’s market produce. Small buildings and shacks that housed the businesses were located on a curved tract of land — just one block off the beach — that stretches from Kalakaua Avenue to Kuhio Avenue. The entrance to the complex is dominated by a huge, old (circa 1850) Banyan tree. This tract is owned by the Queen Emma Land Company. Queen Emma was a Hawaiian Queen from the 1800s. Revenue from the land has supported the Queen’s Medical Center in Honolulu for decades.The reimagined IMP is owned by Taubman Centers, of Bloomfield Hills, Mich., and CoastWood Capital Group of San Francisco, Calif. The IMP will offer a distinctive collection of upscale fashion and lifestyle retailers, including Hawaii’s only Saks Fifth Avenue store, as well as ten sit-down restaurants, including concepts by award-winning chefs Michael Mina and Roy Yamaguchi. The mall features two large open-air courts, the first of which has the huge Banyan tree as its entryway centerpiece. The second open-air court, called Queen’s Court, includes a stage and mature monkeypod trees and a few palm trees. Foundation SelectionAfter a geotechnical exploration that was directed by SME, Plymouth, Mich., and performed by Geolabs, Honolulu, it was discovered that the historical site had hidden and challenging foundation conditions. The subsurface conditions included a very deep but now in-filled ancient river valley containing more than 180 ft (54.9 m) of lagoonal deposits consisting of normally consolidated plastic clayey silts and silty clays with blow counts mainly varying in N-value from 1 to 6. The silt was underlain by several soft coralline layers, some overconsolidated clays and various basalt layers. The static groundwater level on the site was at a depth of about 5 ft (1.5 m), closely matching sea level.Although driven piles had previously been used as the preferred deep foundation support for adjacent structures, this area of town is now fully developed and local noise ordinances preclude their use. Augercast piles were initially considered, but when the general contractor dck/FWF, Pittsburgh, Pa., asked for bids for the augercast piles, several foundation contractors offered alternate systems. The practical installation depth of augercast piles was limited and due to the depth of the in-filled alluvial valley, this system could likely have left soft silt below the tips of the piles over much of the site."

Jan 1, 2016

By Chandramohan P. V., Ravi Kishore

"An underground reservoir was to be constructed at Doha in Qatar. Simsima lime stone is present at the bottom. When the reservoir is empty, there will be uplift at the bottom but this will change to downward load when it is full. The rock at the bottom had high bearing capacity to resist downward load. But uplift had to be resisted by piles or anchors. The reservoir has a size of 120mx80m. Shrinkage and creep of concrete coupled with thermal contraction imposed a horizontal movement of 26mm on the extreme piles. So, piles have to accommodate this as well. This unique situation needed a unique solution. The solution was to provide piles with flexible high tensile strands to take tension. An annular space near the head of the pile would facilitate horizontal movement as well. Compression load was directly passed on to the raft bearing on rock.INTRODUCTIONAn underground reservoir for storage of drinking water was to be constructed at Doha, Qatar. The reservoir was proposed to have a plan size of 120m x 80m. Clear height inside the reservoir was proposed as 17.2m, from the bottom of roof to the top of bottom raft. Overall height of the reservoir at the outlet from the top of the roof to the bottom of raft was to be 21.2m. For the sake of inspection and in order to prevent pollution from the surroundings a gallery was planned around the reservoir. This could accommodate pipelines as well. This gallery was 3.0m wide on three sides and 8.4m wide on the outlet side.The gallery had removable gratings as cover in order to facilitate maintenance. Capacity of the reservoirwas proposed to be 40million gallons. The reservoir is divided into four compartments with baffle walls in each one for water circulation. Roof of the reservoir is kept at 300mm above ground level. There are two levels of car park on top of the reservoir. Top of the reservoir roof is at +14.35. Bottom varies from - 6.68 to -7.08. Lowest water table is at +6.00. Concrete structure of the reservoir was designed by a local consultant. The Navayuga Engineering Company was entrusted with the construction. Please see Figs 1 and 2."

Jan 1, 2017

By Ørjan Nerland, Torgeir Haugen, Astri Eggen, Kjell Karlsrud

"Ground improvement by the deep dry mixing (DDM) method is used in Norway since the late 1970's. A brief review is given of the Norwegian guideline for ground improvement with DDM issued in 2012, but focus is on practical examples and experiences related to improving the stability of excavations and natural slopes in soft clays. Two examples deal with experiences from 10 to 18 m deep excavations in soft and partly highly sensitive clays, where DDM panels and block stabilization were used to both give sufficient stability against bottom heave and to limit lateral wall displacements. A third case deals with improving the stability of a natural slope in quick clay by installing DDM panels near the crest of the slope. To limit disturbance and excess pore pressures generated during the DDM works, vertical drains were installed in advance in between the DDM panels. This ensured that the excess pore pressures generated by the DDM works (up to 150 kPA) dissipated quickly, which was instrumental to avoid triggering a landslide during the stabilizing works.INTRODUCTIONThe lime column (LC) method developed in Sweden and Japan in the mid 1970's (e.g. Broms and Boman, 1977). Since then, there have been significant developments in Scandinavia and around the world in terms of rigs, mixing machinery and tools, and type of binders used. The method, presently named the ""Dry Deep Mixing"" (DDM) method in contrast to the wet deep mixing methods (WDM) that also have developed significantly over the past decades, e.g. Kitazume and Terashi (2013). The first application of the DDM method in Norway was in the late 1970's to improve the stability of an excavation in quick-clay, then using only lime as binder. Most DDM applications in Norway have also thereafter been to improve the stability of cuts, supported excavations or natural slopes in soft clays. The Norwegian Geotechnical Society (2012) issued in 2012 “Guidelines for design of ground improvement with DDM methods"". The following highlights design issues dealt with. The paper focuses however, on some practical cases where DDM has been used to improve stability of deep excavations and a natural slope in soft and partly highly sensitive clays."

Jan 1, 2015

By Miguel E. Ruiz, America L. Fernandez, Miguel A. Pandon

"Post-grouted drilled shafts (PGS) are a deep foundation system in which grout is injected at high pressure throughout the tip after the drilled shaft has been installed. Pressure grouting of drilled shaft tips can significantly increase the ultimate capacity and stiffness of drilled shafts. Conventionally constructed drilled shafts usually require higher axial deformation to develop the available side friction and the tip resistance simultaneously. They also tend to have higher tip compressibility and reduced end bearing capacity due to disturbance at the bottom of excavation during drilled shaft construction. PGS foundations have been found to be a cost-effective solution to compensate for this capacity reduction and/or compressibility increase. PGS construction procedure counterbalances tip compressibility and end-bearing capacity reduction. The tip grouting also has a pre-stressing effect over the shaft side friction since the drilled shaft tends to move upwards during the pressure grouting of the tip. After grouting, a bulb tends to form at the pile tip pre-compressing any disturbed material and, in certain cases, increasing the tip area, thus increasing shaft tip capacity.PGS load-settlement predictions using a load transfer approach are presented in this paper and compared with corresponding load test data. The paper also presents the main findings of load transfer analyses that were carried out to investigate the potential different factors that may be contributing to the observed improved performance of PGS over conventional drilled shafts. Results show that the two main factors, that may have a significant contribution on the overall performance of the foundation by increasing its ultimate capacity at any given level of settlement, are the stress-reversal of the skin friction and the formation of a grout bulb at the tip. The grout bulb tip contributes primarily through the increased tip area and to a lesser extent through increased stiffness and strength of the soil in the vicinity of the pile tip."

Jan 1, 2005

By Gary L. Seider, Dana A. Wesolek, Fred C. Schmednecht

"A new condominium project, The Atelier, developed by Pickus Companies located at the corner of Bryn Mawr and Sheridan in Chicago, IL required an earth retention system to protect the surrounding roads, alley, and existing neighboring apartment bui lding during its construction. Slurry Systems, Inc. (SSI) and Ground Engineering Consultants, Inc. designed the earth retention system using cantilevered sheet piling for three of the four sides: two sides bordering major streets and one side bordering an alley. For the fourth side, which borders an existing occupied brick building, a combination of sheet pil ing and AB. CHANCE® helical screw piers were used. SSI was actively involved in the review process of its earth retention system with the City of Chicago and quickly learned that there was no specific code for hel ical piers/anchors. (It appears that this is the case with most metropolitan cities throughout the United States). Consequently, the approval of underpinning for this project became the critical path, as much testing, calculations, meetings, and other details were required prior to its approval.SSI and AB. CHANCE® recognized that this process for underpinning approval must be seen by other contractors/suppliers who wish to use helical piers/anchors in the City of Chicago. Consequently, this project served as an opportunity to work with the City of Chicago and the City's Building Code Committee in furthering the development of the Helical Piers/Anchors Code, Section 1814. INTRODUCTION - HELICAL PIERSDefinition. A helical pier or anchor consists of one or more helix-shaped steel bearing plate(s) attached to a central steel stem (solid bar or pipe), which is installed by rotating or ""torquing"" into the ground. Each helix is attached near the tip, is circular in plan , and is formed into a screw thread with a defined pitch. Helical piers/anchors are pre-fabricated and can derive their load-carrying capacity through both end bearing and skin friction. The helical piers/anchors can be augmented with grout."

Jan 1, 2005

By Babak Mamaqani

The Regional Connector Transit Corridor (RCC) is the Los Angeles Metro area's ambitious light rail project, running under the city's main thoroughfares, Flower and 2nd streets. When com- pleted, it will alleviate traffic and parking congestion downtown, while connecting thousands of residents living in the bedroom communities of Inland Empire and Long Beach to their jobs there. The rail line of 1.9 mi (3 km), which involves a $1.756 billion (€1.545 billion) budget to construct the under- ground rail line, including three new stations. They are the Grand Av Arts/Bunker Hill station at 2nd and Hope streets, Historic Broadway Station at 2nd Street and Broadway, and Little Tokyo/Arts District Station at 1st Street and Central Avenue, which will offer riders their first "one seat/one fare" ride option from Azuza to Long Beach. Regional Connector Constructors JV is led by Skanska USA Civil West California District Inc. (Skanska), in partnership with Traylor Bros., Inc. (Traylor), to deliver RCC to the Los Angeles County Metropolitan Trans- portation Authority (Metro). PB&A was the structural engineer of record (SEOR) responsible to design the shoring systems for the Grand Av Arts/Bunker Hill Station at 2nd and Hope streets, and Historic Broadway Station at 2nd Street and Broadway. The temporary shoring design for Historic Broadway Station is the focus of this article, and why the project received special recognition as a runner up for DFI's 2021 Outstanding Project Award. Two main challenges are discussed in particular: design of the shoring system considering all construction stages, and design of an underpinning system where the Los Angeles Times Building (Times Building) protruded into the station footprint.

Apr 1, 2022