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By Alice Y. Tseng, Dan MacLean

"Corrosion protection of all deep foundation systems made of steel is THE issue when considering durability of the element in the long term. Protecting steel from corrosion and maintaining the steel tendon cross sectional area ensures a competent and durable system. The foundation of a building is usually difficult to repair and therefore high risk is taken when unknowingly choosing a non-adequate solution.Requirements according to EN 1990 (Eurocode 0 or EC 0) on construction durability requires a service life over 100 years. How can a service life over 100 years be achieved? How shall bare steel be protected in soil, which sometimes could be an aggressive environment to the steel? Which corrosion protection methods are commonly used in Europe and in North America?This paper will focus on hollow bars used as Micropiles, Anchor piles and Soil Nails. It gives an overview about the state of the practice in regards to corrosion protection (including head construction) and evaluates different options following the European Standards focusing on type of material and method of installation. Further the different corrosion protective methods such as thickness of grout body, coating types and sacrificial loss are listed with the pros and cons evaluated.Based not only on North American standards like FHWA “Micropile Design and Construction Guidelines”, FHWA Geotechnical Engineering Circular No. 7 for “Soil Nail Walls“ and Post-Tensioning Institute “Recommendations for Prestressed Rock and Soil Anchors”, but also European standards like EN 14199 “Execution of special geotechnical works – Micropiles”, EN 14490 “Execution of special geotechnical works - Soil nailing”, EN 1537 “Execution of special geotechnical work – Ground anchors“, and other relevant standards, all possibilities of protecting the hollow bars and the steel quality will be introduced, discussed and compared ."

Jan 1, 2017

By Dino Kartofilis, Rick Deschamps, Giovanni (John) Bonita

"Anew condominium complex in Arlington, Va., presented some formidable constraints. One was the requirement for a permanent retaining wall to support a 48.5-ft (15-m) cut and an existing 16- story building on top of the slope. Another was the adjacent property owners’ refusal to allow tieback anchors to encroach on their property. The General Contractor (GC) proposed an innovative design incorporating vertical concrete load-bearing elements (LBEs) supported by post-tensioned tiedowns. The owner accepted and the project was successfully completed in 2007.The original designer had proposed a system that included a temporary, raked soldier pile and lagging wall and a permanent cantilever retaining wall with a large piled footing. The system was potentially costly and its constructability questionable.The GC then asked for a design-build alternative to reduce costs and enhance the schedule. The first idea was a diaphragm wall with vertically anchored T-sections. However, configuring a crane to excavate perpendicular sections using grab equipment seemed impossible. There were also utilities approximately 25 ft (9 m) from the existing building, two tiered retaining walls down the slope and a large swimming pool at the base. However, the GC was committed to providing a stable bench 20 ft (6 m) wide along the wall alignment to support the crane.The design evolved to single bite panels using diaphragm wall technology, commonly called LBEs, or barrettes, when they carry vertical loads. For this project, 44 LBEs were horizontally spaced at 9 ft (2.75 m) on center, oriented perpendicular to the wall, extending into bedrock and anchored vertically on the upslope side to resist overturning moments. They were essentially large soldier piles that provided both temporary and permanent support of excavation.An unusual formal agreement was established with the GC to complete the work based on pricing, and prior to completion of final design. This arrangement allowed for an exchange of ideas that increased project efficiencies and lowered costs — without the fear that design concepts would be “shopped” to competitors."

Jan 1, 2009

By Marcel Bielefeld, Joost Bakker, Rob van Dorp

Pile load testing can be performed by a static, rapid or high strain dynamic (generally designated as dynamic) testing method. The static load test is often considered the “gold standard” of testing with the other methods merely ‘alternatives’. However, the rapid load test, as a quasi-static test, has all the positive elements of the static alternative: the direct measurement of loads and displacements. Moreover as stress wave phenomena have no influence, the interpretation of rapid load test results is more straightforward than that of dynamic testing, and also independent of the person performing the interpretation. This paper will explore the Rapid Load Testing method and illustrate the advantages and limitations through a case study in Rostock, Germany

May 1, 2022

By Tony Amis, Marco Barla, Alice Di Donna

"Energy geostructures are becoming an increasingly popular solution around the world for Developers looking to reduce CO2 and system running costs. Energy geostructures are geotechnical structures that provide both the important role of structural stability while also acting as a heat exchanger with the ground, enabling the supported buildings and or infrastructure to be heated and cooled using the principle of low enthalpy geothermal systems. The main advantage of this innovative technology with respect to standard geothermal plant is the reduction of the initial installation costs and construction schedule benefits, compared to installing conventional geothermal solutions, largely due to the additional use of structures which would be constructed in any case. However, it is important with respect to energy geostructures that additional aspects need careful consideration. For this very reason, several research studies have been carried out over the last decade on this subject and a number of real case studies have been monitored and analysed. The key difference with respect to conventional shallow geothermal systems are mainly related to the geometry, which is imposed by the geotechnical project, and the need to ensure that the primary structural role is always guaranteed. Special boundary conditions, the reduced depth, the influence of atmospheric external temperature can also play an important role for energy geostructures. They can affect, both energy efficiency and, the geotechnical behaviour because of the possible thermal induced mechanical effects. This paper presents a picture of the current situation regarding energy geostructures and their peculiar features, and collects available data to provide a reference framework. Data has been collected from literature and personal communications and then processed to provide easy-to-read charts useful for practical consultation at a glance. This paper provides, an indication of the distribution of such systems worldwide, their spread in time, and a global view of their actual efficiency from the structural, energy, economic and environmental point of view.1. IntroductionEnergy geostructures are becoming an increasingly popular consideration around the world. Energy geostructures are geotechnical structures with a dual role of providing structural stability and the ability to exchange heat with the ground, to provide low carbon heat and coolth to supporting and or adjacent buildings and infrastructure, using the principle of low enthalpy geothermal systems (Barla and Di Donna, 2016; Laloui and Di Donna, 2013). A closed circuit of high density polyethylene (HDPE) pipes is embedded in the concrete, and a heat carrier fluid circulates through them exchanging heat with the ground. The HDPE pipework circuit inside the geostructure is linked to one of the above buildings or infrastructure through a heat pump, which adapts the temperature of the circulating fluid to the heating (winter mode) and cooling (summer mode) needs. In this way, heat can be injected into the ground during summer and extracted from it during winter. In principle, all structures in contact with the ground can be used as energy geostructures. The first examples of energy geostructures date back to the eighties in Austria and were mainly piles and shallow foundations. A decade later, Henderson et al. (1999) reported on what would appear to be the first successful use of geothermal energy piles in the US, with loops incorporated into the foundation for a hotel in Geneva, New York. As was their use in this New York case history, the typical geothermal energy pile application is used in conjunction with additional closed loop boreholes to provide the required energy capacity for a structure. Interestingly the report concludes that the geothermal energy piles had a better heat transfer performance than the borehole field. The first energy walls appeared slightly later, while still today only a few experimental cas"

Jan 1, 2017

By Dominik Gächter, Wojciech Szczepiñski

In early 2020, the construction phase began for the new complex of buildings for Radium Hospital in Oslo – the leading facility for cancer treatment in Norway. Settlements in the surrounding area, caused by pore pressure changes, allowed for the introduction of an alternative solution for the construction of the excavation pit. The presence of solid bedrock and sensitive clay – the same material that causes major landslides in the Scandinavia – in the excavation pit, lead to a combination of techniques, which were never applied in Norway before. For the stabilization of the clay Dry Deep Soil Mixing was applied to allow safe execution of the geotechnical works. Interlocking Bored Piles with footbolts and Jet Grouting columns, in combination with anchors, provided the retaining structure for the excavation pit. Rock injections were performed to avoid any ground water ingress into the pit. Underpinning of fully operational, adjacent buildings was carried out with jet grouting columns. These works were performed from the basement of the hospital and the ‘ACI – Acoustic Column Inspector’ was used to ensure proper installation of 2 m diameter columns to a maximum depth of 25 m. The buildings were later founded on Steel Core Piles, the most common pile type in Scandinavia.

Sep 8, 2021

By Wojciech Szczepiński, Dominik Gächter

In early 2020, the construction phase began for the new complex of buildings for Radium Hospital in Oslo – the leading facility for cancer treatment in Norway. Settlements in the surrounding area, caused by pore pressure changes, allowed for the introduction of an alternative solution for the construction of the excavation pit. The presence of solid bedrock and sensitive clay – the same material that causes major landslides in the Scandinavia – in the excavation pit, lead to a combination of techniques, which were never applied in Norway before. For the stabilization of the clay Dry Deep Soil Mixing was applied to allow safe execution of the geotechnical works. Interlocking Bored Piles with footbolts and Jet Grouting columns, in combination with anchors, provided the retaining structure for the excavation pit. Rock injections were performed to avoid any ground water ingress into the pit. Underpinning of fully operational, adjacent buildings was carried out with jet grouting columns. These works were performed from the basement of the hospital and the ‘ACI – Acoustic Column Inspector’ was used to ensure proper installation of 2 m diameter columns to a maximum depth of 25 m. The buildings were later founded on Steel Core Piles, the most common pile type in Scandinavia.

Oct 1, 2021

By Sebastian Lobo-Guerrero

Welcome to DFI45! our first on-line annual meeting. We cannot deny the severe impacts that the COVID19 pandemic is having in our industry and our lives. We extend our support to all of our members that have been impacted in many different ways. But through the middle of this difficult and challenging times, our beloved annual conference emerges, trying to re-unite our industry and remind us why we love what we do so much. DFI45 was not originally planned to be delivered virtually, but as our world changed, we adapted. Adversity became an opportunity to re-invent our annual conference. Thanks to the vision of our Organizing Committee, we saw the amazing new possibilities and DFI45 is today a reality. Our theme for this year is People + Purpose + Passion. This theme was decided before the COVID 19 pandemic started, but today it is more relevant than ever before. We are a group of very diverse people at DFI. Our organization includes Contractors, Consultants, Suppliers, and Academics just to name a few sub-groups. But we all have a common purpose and try to find common ground. We are all extremely passionate about what we do, and this excitement is really what makes this organization what it is today. This conference celebrates this passion as you can see in our three main Keynote Sessions. On a local scale, we want to go back and remember the contribution of our industry to our beloved National Monuments in Washington D.C. On a national scale, we want to explore and recap the development of Government Guidelines and Specifications that became the world standards. And finally, we want to close the conference with a session celebrating the family legacy and share amazing stories of families with multiple generations working in our industry. Besides our Keynote Lectures, the conference is full of exciting content such as several case histories, experimental research in deep foundations, applications of new technologies, business aspects and risk management considerations for deep foundations, just to list a few. We also have our now traditional events such as the Hal Hunt Lecture, Awards Reception, DFI Educational Trust 5K Fundraiser, etc. For the first time, all this content will be delivered using different virtual formats, including on-demand presentations, plenary sessions, interactive chat rooms, etc. We are excited about these possibilities. To conclude, we need to recognize the people that against all odds made this conference a reality. First our sponsors, they adapted to the most abrupt change never thought before, and they always stayed there with us, providing unconditional support. Without them no conference is possible. Next, our Organizing Committee that re-invented the concept of an annual conference and found new and exciting ways to make this happen! Our Technical Program Committee led by our Technical Program Chairs, Jennifer Nicks and Gregg Piazza, showed us that nothing is impossible. And last, but not least, the amazing DFI staff that make dreams reality. It has been an honor to serve as the Conference Chair for DFI45. It is an experience that will stay with me for the rest of my career. Conference Chair: Sebastian Lobo Guerrero, Ph.D., P.E. American Geotechnical and Environmental Services (A.G.E.S.)

Oct 27, 2020

By Donald A. Bruce

Various types of contemporary Deep Mixing Method (DMM) techniques have been used in the United States since 1986. Such techniques owe their origins to Japanese and Scandinavian developments, which began almost three decades ago. The growing demands of urban infrastructure development and rehabilitation have created a very active and rapidly expanding market demand in the United States especially since the early 1990s, and there is a clear need for a new and fundamental review of the surprisingly large number of DMM techniques that are being used domestically, or are available in other parts of the world. Following a summary tracing the historical development of DMM, and a generic classification of applications, the paper provides a review of each of the many different proprietary methods, which the authors have identified during preparation of an international survey funded by the Federal Highway Administration (FHWA). Data are also provided on commercial aspects of the various DMM techniques worldwide.

Jan 1, 1998

By Charles M. Wilk, Lori Tiefenthaler

"Information presented in this paper can be used to support deep soil mixing, subsurface grouting and slurry wall technology as sustainable construction technologies. Ordinary Portland Cement (OPC) is the default cementitious material used by Deep Foundation Institute (DFI) Members for geotechnical work. Owners, engineers and contractors can contribute to the sustainability of a geotechnical project by increasing the use blended hydraulic cements and industrial byproducts to replace some of the OPC in mix designs. Sustainability is defined as the quality of not being harmful to the environment or depleting natural resources. Production of cementitious materials consumes natural raw materials and energy while also generating air emissions and waste. Life Cycle Assessments can be used to compare the relative environmental impacts of one cementitious material to another. Blended hydraulic cements (BHCs) are interground (or blended) mixtures of Supplementary Cementitious Materials (SCMs) with OPC. Commonly used SCMs include fly ash, ground granulated blast furnace slag (GGBFS) and limestone. Examples of industrial byproducts commonly used in geotechnical work include coal combustion residuals (CCR) (aka fly ash), and ground granulated blast furnace slag (GGBFS). Much of life cycle impact of these SCMs and industrial byproducts have already been borne by the industries that generated them. There is increasing awareness to LCA and sustainability of different materials used on projects. This is evident in the application of the Leadership in Energy and Environmental Design (LEED) program. The savings in environmental impact with the use of SCMs and industrial byproducts can make proposed use of these materials in a geotechnical project more attractive in terms of sustainability. This paper presents (a) information that compares published life cycle assessment data of OPC, BHCs, and slag cement (SC) to illustrate the potential benefits to sustainability and (b) general strategies for positioning a geotechnical application, use, project design or cementitious material mix as a more sustainable alternative"

Jan 1, 2017

By Marco Fellin, Van E. Komurka

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

Jan 1, 2019

By Jan A. Nilsen

This paper describes a key element in the construction of a major project undertaken by Harbourfront Corporation in its efforts to rejuvenate the central Toronto waterfront. The Spadina Pier forms one of the two major structures of the $10 million marina complex. Completed in early 1986, the 150 metre(490 ft.) long by 43 metre(140 ft.) wide pier structure will contain a 320 car parking garage as well as providing the foundation of a 17-story residential tower and a two-story retail/commercial complex. However, the pier structure posed a considerable challenge to its developers due to the the many restrictions imposed on the site by the environmental authorities which ruled out the construction of dykes or the placing of other fill materials on the highly contaminated bottom sediments. In addition, access at the site was restricted by its proximity to the main harbour navigation channel and a grain elevator berth. The original design called for a cofferdam to form an integral part of the finished structure. However, the contractor chose to regard the cofferdam as a temporary structure and proposed to construct the pier in the dry by enclosing the 10,000 square metre(107,600 sf) site with a 450 metre(1480 ft.) long single wall steel sheet pile cofferdom 7.5 metres(25 ft.) from the final pier structure. This paper will describes the design and construction of the cofferdam. Prior to finalizing the pier design, a geotechnical investigation of the shale bedrock was undertaken as well as a small sheet pile test cell program to evaluate the feasibility of driving a Canadian manufactured cold-rolled sheet pile into the bedrock. Relying on the design parameters for the shale bedrock, Foundation designed the cofferdam utilizing a post-tensioned bipod bracing system to resist a 7 metre(23 ft.) hydrostatic head as well as the maximum wind and wave forces expected at the site. The bipod bracing system consists of diagonal H-pile raker piles and verticle pipe piles anchored to bedrock with post-tensioned anchors grouted into bedrock.

Jan 1, 1987

By Babak Mamaqani, Pirooz Barar

Regional Connector Transit Corridor (RCC) is part of the Los Angeles metro expansion project under construction which adds three new stations into the system. PB&A was responsible for the design of the support of excavation (SOE) systems for two stations, 2nd/Broadway and 2nd/Hope, in RCC. In this paper, challenges and lesson learned from SOE design of 2nd/Broadway station with a main focus on underpinning design are discussed. 2nd/Broadway station required to cut and cover excavation of 500 ft long by almost 100 ft deep, underneath 2nd Street. SOE systems consisting of drilled soldier beams with tiebacks and/or struts. The main challenge in 2nd/Broadway station was to underpin the LA Times building which was partially protruded into the station. A chellenging underpinning system consisted of concrete panels and ground anchors was designed to support the building surcharge and prevent settlement. The underpinning system was designed based on METRO design criteria and the deflection was evaluated by Finite Element Analysis (FEA) program, PLAXIS 2D. A maximum deflection of 0.4 inches was calculated to occur at the top of the underpinning system. Data from settlement and tilt sensors showed minimal movements which aligned with PLAXIS outputs. PROJECT DESCRIPTION The Regional Connector Transit Corridor (RCC) is Los Angeles Metro’s ambitious Light Rail Project. It runs under the City’s main thoroughfares, Flower and 2nd Streets, and when complete will alleviate traffic and parking congestion in downtown Los Angeles. The Regional Connector will connect thousands of residents living in the bedroom communities of the Inland Empire and Long Beach to their jobs Downtown. The rail line will serve 1.9 miles, using the $1.756 Billion budget to construct the underground rail line, including 3 new stations, at 2nd & Hope Street, 2nd & Broadway, and 1st St. & Central Ave (Fig. 1).

Jan 1, 2019

By Robert B. Bittner

The new gated dam on the Monongahela River at Braddock, Pennsylvania, was built for the US Army Corps of Engineers using an innovative "In-the-Wef' technology. A key feature of this technology involves construction of the foundations through the water and later mating the completed structure or a shell of the structure to the pre-installed foundation. This paper presents a description of the structure, its foundation, construction sequence and design details required to successfully Implement this technology.

May 11, 2007

By Ahmed Elmekati, Frederick C. Rhyner, Steven R. Lowe

"The current phase of the Pacific Park development (formerly, Atlantic Yards) in Brooklyn involves constructing buildings on a platform over an existing LIRR rail yard. To preserve the maximum amount of space in the already congested yard and protect the yard which remains in service during construction, high capacity foundations are being designed well above previous capacities in the area. In addition to spread footings and small mats, various diameters of drilled piles are being used at design capacities ranging up to 600 tons. The piles are generally grouted at low pressure, up to about 50 psi. Load tests for various drilled elements, including piles, tiedowns and soil anchors, have confirmed allowable side resistance (bond) stresses in dense sand ranging from 20 to 30 psi. Testing with different rigs and operators has shown that down-the-hole hammers are feasible, but the installation techniques, types of equipment and size of the pile make a significant difference. The results show that more cost-effective foundations are possible when ample testing confirms expectations.I INTRODUCTIONThe Long Island Rail Road has operated a mainline on Atlantic Avenue since the 1800s, with a terminal at the intersection of Atlantic and Flatbush Avenues. In the early 1900s, the mainline was reconstructed in a cut and cover tunnel section. The LIRR’s Atlantic Yard was constructed circa 1908 to service the terminal. It was depressed about 25 feet below street grade to coincide with the LIRR’s mainline tunnel under Atlantic Avenue. Record drawings indicate that the gravity retaining walls lining the perimeter of the yard and other ancillary structures had been designed for an allowable bearing pressure of five tons per square foot (tsf). Perhaps by coincidence, the mat foundation for the tower of the Williamsburg Savings Bank was also designed for five tsf in 1929.Figure 1 shows a typical geologic section through the site. The geology and subsurface conditions in this part of Brooklyn consist of fill generally five to 20 feet deep underlain by dense to very dense sand and gravel; in places, with numerous cobbles and boulders which make pile installation challenging. The sand strata that are on the order of 150 to 200 feet thick were laid down by glaciers during the last ice age and have been heavily precompressed. The sand strata are underlain in places by remnants of the Cretaceous-era Raritan Clay formation and Fordham Gneiss bedrock. Because of this, the sand strata generally provide excellent support for shallow foundations and the allowable bearing of five tons per square foot is usually easily justified."

Jan 1, 2016

By Jeff Hopple

"Bluestone Dam in Hinton, W.Va., along the New River, is owned and operated by the U.S. Army Corps of Engineers (USACE). Completed in 1949, the dam is 165 ft (50 m) tall, 2,048 ft (624 m) wide, and encompasses a water shed that is 4,600 sq mi (11,914 sq km). The Bluestone Dam Safety Assurance (DSA) Program began in 2001, and is a multiple-phase construction project to upgrade the capacity and stability of the structure to meet the probable maximum flood event. Installing 216 high capacity rock anchors was a major feature of the work.The USACE selected Brayman Construction Corporation to perform Phase 2B of the construction modifications to the Bluestone Dam. Brayman was responsible for installing the high capacity rock anchors, which range in size from 3 to 61 strands and have a design load up to 2,145 kips (9,541 kN). Drill holes range in size from 6.5 to 15 in (16.5 to 38 cm), and required full length corrosion protection. Of the 216 anchors, 57 were installed on top of the dam to resist overturning and the remaining 159 were installed on the face of the dam at a 45-degree angle to resist sliding.To gain access to the face of the dam anchor locations, the project required dirt benches, excavations with temporary shoring, and steel platforms. To access anchors on the east and west abutment faces, the team excavated over 10,000 cu yds (7,645 cu m) of material. Support of these excavations included the design and installation of three soil nail walls with over 145 nails and 3,500 sq ft (325 sq m) of shotcrete. The project also called for a 780 ft (237 m) long steel platform to gain access to the spillway anchors. The Stratus Group designed the platform to support two 85 ton (80 tonne) crawler cranes and as many as five drill rigs that were the equivalent to a design load of 3.5 ton per sq ft (335 kN per sq m). Once the final platform design was approved, fabrication of roughly 3 million lbs (1,360 tonnes) of structural steel began. Brayman’s in-house fabrication shop, in conjunction with Dura-Bond Industries and Advantage Steel, collaborated to fabricate and install the platform in less than five months. Flexibility in the platform design allowed for sections of the platform to be lowered as much as 16 ft (4.9 m) to provide access to anchors at lower elevations along the spillway face. In addition to the main spillway platform, Stratus Group, Brayman, Dura-Bond and Advantage designed, fabricated and installed six other unique platforms to facilitate anchor construction on various areas of the dam."

Jan 1, 2014

By Gregory M. Landry

"There is an old joke at Moretrench that defines dewatering as “that element of an underground construction project, which, when disregarded, will generate the low bidder.” Sigmund Freud wrote that all jokes are true, and the kernel of truth behind this one is that dewatering is often misunderstood or neglected until the last possible moment in the life of a project. The purpose of this article is to describe commonly used dewatering methods and to clear up a pervasive but fundamental misunderstanding about how to determine the amount of dewatering effort required for a project. The Tools of DewateringDewatering may be divided into two broad categories: (1) methods that remove water from the excavation after it has already entered and (2) methods that seek to exclude or intercept the water before it reaches the excavation. The former is generally self-performed by general or earth moving contractors using sumps and ditches, while the latter is usually done by a specialty contractor. SumpsProperly installed sumps can be an effective and economical way to control water inflow into a site. In this technique, groundwater is allowed to enter the site before being pumped away. Advantages of this method include lost cost, easy availability of equipment and the fact that a general contractor can self-perform the dewatering. However, caution should be used when deciding whether to use this method, and consideration should be given to the following factors:1. How will the soil behave under seepage forces? Will it run, potentially causing ground loss?2. How much groundwater lowering is required? If the groundwater only needs to be lowered a few feet, using sumps will be much more practical than for a situation that requires significant drawdown.3. Will the excavation subgrade soften or otherwise be damaged by allowing water to run over it?4. Is my workforce skilled enough to implement and manage the sumping plan?In the photo, the sump is capturing groundwater that has already entered the excavation by traveling under the sheets. In this instance, the house in the background of the photo was eventually purchased by the project owner after sustaining damage due to ground loss."

Jan 1, 2017

By Federico Pagliacci, Claudio Asioli, Marco Chiarabelli

"""Rigid inclusions"" are a consolidation method that provides improvement of soft soils thanks to the installation of cylindrical columns made up of a material with significant and permanent cohesive properties, whose stiffness is 500÷5000 times greater than the surrounding natural soil’s. ""Rigid inclusions"" find their application in marginal areas (reclamations, polluted sites) to ensure stability of adjacent structures during construction of new buildings and to reduce the impact of natural disasters (liquefaction in the event of earthquakes, embankment collapse in the event of floods). This paper analyses the “rigid inclusion” construction method, related materials and equipment. Moreover, two performed projects will be illustrated. The first is the restoration of Lungarno Torrigiani Embankment in Florence, Italy. In May 2016, the Torrigiani embankment underwent a structural collapse causing a 3 m. displacement of the riverbank towards the Arno River. “Rigid inclusions” (with 300 mm diameter) have been used to re-compact the loose soil and create a stable working platform for the equipment. The second project illustrates the use of “rigid inclusions” (800 mm diameter and maximum depth of 36.6 m) to control the settlement of a new automatic cold store (30 m high with a 65 x 120 m foot print) for fresh frozen vegetables.RIGID INCLUSIONSIn general, the word ""inclusions"" means a type of consolidation that improves the strength of a soil mass through the inclusion of elements constituted by a material having better characteristics than those of the surrounding natural ground, to improve the overall mechanical characteristics of the treated soil. Inclusions are ""rigid"" when the material introduced into the ground has significant and permanent cohesive properties (concrete or cement mortar) and a significantly higher stiffness (500 ÷ 5000 times) than that of the surrounding natural ground.Typically, medium-small diameters (from 300 to 800mm) with low percentages of treatment (from 2% to 10% of the volume of soil) are employed, ensuring a high quality and consistency of the obtained product, both in terms of diameters and elastic modulus.According to the scope of the project and in urban areas, ""rigid inclusion"" columns can also be performed by means of small diameter drilling rigs (micropiles), weighing less than 20-25 tonnes."

Jan 1, 2017

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface. Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone."

Jan 1, 2017

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface.Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone"

Jan 1, 2017

By Wanchai Teparaksa

Pile deviation generally can happen after installation of driven pile particularly in soft soil layers. In this case study, all 242 diameter 0.8 m spun piles were deviated from 20 to 820 mm. The large deviation was caused by lateral soil movement in the top very soft clay layer of thickness about 23 m. This very soft marine clay is very sensitive and anisotropic having high water contents of over 120% and low undrained shear strength of 5-10 kN/m2. The remedial works were carried out based on theory of load transfer and soil-structure interaction. All deviated piles were rectified and used as the foundation piles with strictly controlled pile load tests. The construction of a nine-storey building was successfully completed founded on the rectified piles and it has been opened for the service for over two years.

Jan 1, 2002