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By Remo Grandori

"INTRODUCTIONDouble Shield TBMs were introduced in the market in the early seventies with three main targets:• Increase the TBM performances in term of advance per day thanks to the ability to erect a segmental lining simultaneously with the excavation phase.• Be able to advance through unstable and disturbed rocks under the protection of the shields• Provide a finished tunnel by installing a precast lining as the TBM advance.In 2003 SELI developed the design of the Double Shield Universal (DSU) TBM as an evolution of the original Double Shield TBM design.This new TBM design was targeted to improve: the TBM capability to advance through squeezing/converging rock formations under high cover, the telescopic joint design (allowing by such to operate the machine in double shield mode in very weak rock), the capability of the TBM to investigate and treat the ground around and ahead of the tunnel face.In the same lapse of time Single Shield TBMs, originally utilized for soft ground tunnelling, extended progressively their range of application to mix rocks and finally to hard rock tunnelling with increasing performances.This also thanks to the substantial reduction in the installation time of the segmental lining ring that contributed to minimize the TBM stand by time between two consecutive boring strokes.Today the choice between the two types of TBMs needs to be carefully evaluated project by project since one type of TBM may “prevail” in certain geologies and diameters and vice versa.THE VISHNUGAD PIPALKOTI TUNNELThe Vishnugad Pipalkoti Tunnel is part of the 444 MW Vishnugad Pipalkoti Hydro Electric Project (VPHEP) on Alaknanda river in Uttarakhand (India).The Owner is the Indian electric company “Tehry Hydro Development Corporation” (THDC) and the World Bank finances the project.The Headrace Tunnel total length is 13.4 Km and a section of about 12,3km will be excavated by TBM by SELI Overseas (Italy) in subcontract to HCC (India) the General Contractor for the project. The TBM will be delivered ex workshop in March 2016 and it is foreseen to start boring in the second half of 2016.Figure 1 below shows the location of the project and the following Table 1 summarizes the geometrical characteristics of the TBM tunnel."

Jan 1, 2016

By M. Hesham El Naggar, Maged A. Abdlrahem

"Hollow bar micropiles have constructional advantages such as: fast and low-noise and low vibration installation process and small installation equipment, which allow access to tight places. In addition, they have efficient load transfer mechanism, which facilitates carrying considerable load in compression and tension. The common practice is to use diameter ratio of drill bit/ hollow bar (Db/Dh) around 2 in their construction, and they are typically designed assuming type B as classified by the Federal Highway Administration (FHWA). In this paper, the performance and capacity of Hollow bar micropile with different (Db/Dh) ratios are investigated. Full-scale micropiles were installed at a site in Ontario, Canada, and were tested in order to evaluate the uplift performance of Hollow bar micropile with different(Db/Dh) ratios. Two micropiles with two different ratios 2.25 and 3 were constructed and tested. The total length of the micropiles was 6m with embedded length of 5.75m. The soil at the site was primarily medium dense to dense sand. The results of the load tests are presented and discussed. It was found that the uplift capacity of the micropile increased by about 19.5% as Db/Dh increased from 2.25 to 3.INTRODUCTIONMicropile is a small diameter, less than 300 mm, drilled and grouted pile and is typically reinforced according to Federal Highway Administration (FHWA, 2005). The technology of micropile was introduced in North America in 1970’s, but the growth in the east coast of United State was intense compared to all other cities around the globe (Bruce and Nicholson, 1989). Nowadays, micropile construction is used extensively worldwide as a viable solution that offers several advantages such as fast installation in low headroom, minimal disturbance to the adjacent structure efficient load transfer due to high grout to ground bond strength. As the method of grouting has major influence on the grout – ground bond strength, FHWA has classified the micropiles into four categories. Type A: the grout is placed under gravity and no pressure is required. Type B: The grout is typically pressurized under a pressure range from 0.5 to 1 MPa as the temporary casing is withdrawn. Type C: the grout is placed in two-step process. First, the grout is poured under gravity only as in Type A. Before the hardening of the grout, similar grout is pressured of at least 1MPa without the use of packer. Type D: Like Type C, it is a two – step process, the grout is placed under gravity as in Type A and sometimes pressurized as in Type B. After hardening of the initial grout, additional grout is pressurized between 2 to 9 MPa through sleeved pipe by using packers, as many times as needed. According to this classification, hollow bar micropile is usually designated as Type B. However, the construction technique is completely different from Type B. Recently; there is a trend to supplement the four types of micropiles by Type E as represent to hollow bar micropile (Timothy et al, 2012). The construction method of hollow bar micropile involves two main stages which can be performed in one–step process: advancing the drilling bit attached to a threaded hollow bar to the required depth; and pressurizing the grout through nozzles of the drill bit."

Jan 1, 2016

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 Mohamed A. Mansour, Ahmed M. Soliman, M. H. El-Naggar

"Grouted helical piles allow significant increase in pile capacity with low additional cost over that of conventional helical piles. They can be particularly advantageous in sites where installation disturbance can reduce or even eliminate the pile shaft resistance. For helical piles with slender shafts, a grout column offers increased buckling resistance under compression loading, and may reduce the potential settlement required to mobilize the bearing component of their plates. This paper investigates the performance of grouted helical piles installed in loose sand. Grouted helical piles were constructed and tested in a controlled laboratory environment. Helical piles with hollow pipe shaft and single helix were grouted during installation. The grout was injected into the soil under high pressure through two nozzles placed above the piles helices. The load test results showed significant improvement in the performance and load carrying capacity of the helical pile due to the formation of a cylindrical grout column along the entire shaft leading to a higher shaft resistance contribution to the total pile capacity. The results suggest that grouted helical piles with slender hollow shaft could be used to support large structural loads. INTRODUCTIONHelical piles are widely used as a deep foundation system for different engineering applications. They represent an attractive foundation option because of their cost effectiveness, ease of installation even in limited access areas, low levels of noise and vibrations, and their ability to be installed through ground water without casing. In addition, they allow immediate loading upon installation. Helical piles are installed into the ground by applying a mechanical torque to the pile head. The installation torque monitoring provides a kind of quality control during the construction of helical piles. It could be used in predicting the ultimate pile capacity using several capacity-torque correlations (Livneh and Elnaggar 2008; and Hoyt and Clemence 1989).However, helical piles installation can cause soil disturbance within the annular zone affected by the pile helices. This disturbance can introduce fissures within the pile cylindrical failure surface (Vesic 1971; Mooney el al. 1985; and Zhang 1999). Thus, the shear strength of the soil decreases along the affected zone. Bagheri and El Naggar (2013) evaluated the installation effects of helical piles in sand. They reported that as the helical blade proceeds into the ground, sand within the cylindrical path circumscribed by the helices experiences torsional and vertical shearing accompanied by sand displacement and stress changes. This process is more pronounced in the case of multi-helices and large diameter anchors. Bagheri and El Naggar (2016) evaluated the installation effects of helical piles in structured clay. They indicated that the behavior of the helical pile and its capacity are significantly affected by the degree of soil de-structuring induced by the penetration of the pile shaft and helices. In addition to the installation disturbance, helical piles have other drawbacks including; high potential settlement required to fully mobilize the bearing component of their plates, low buckling resistance of their slender shafts, and the incomplete rigidity of the coupling joints along the pile shaft that allow some lateral movement under compression loading (Vickars and Clemence 2000)."

Jan 1, 2016

By John P. Turner, Steven S. Dapp, Dan A. Brown

"The Goethals Bridge Replacement (GBR) spanning the Arthur Kill Waterway between Elizabeth, NJ and Staten Island, NY is supported on over 200 drilled shaft foundations ranging in diameter from 4.5 ft to 10 ft and socketed into Passaic Formation siltstone. Four drilled shafts, two on each side of the bridge (NJ and NY), were load tested using the bi-directional axial load method. Axial test results demonstrate that RQD, taken by itself, is not necessarily a reliable indicator of side or base resistance. High recovery with low RQD can be a function of horizontally bedded siltstone and shale where the individual pieces of core do not exceed four inches, but may still provide very high side and base resistance. Axial testing was followed by a lateral rapid-load test (Statnamic) on each of the same four shafts. In addition, one of the shafts was subjected to a static lateral load test to validate the rapid-load method as being representative of static loading conditions. Results of the axial load tests provide the basis of unit side and unit base resistances used in the LRFD design of the rock sockets for axial loading, while results of the static and Statnamic lateral load tests were used to calibrate p-y curve parameters used for design under lateral and moment loading. This paper describes implementation of the load testing program and its role in the design process.INTRODUCTIONDesign of drilled shaft foundations for the Goethals Bridge Replacement (GBR) required load testing in order to validate the parameters used for calculating geotechnical axial and lateral resistances. The bridge, including foundations, was designed in accordance with the AASHTO LRFD design specifications, 6th Edition (2012). The bridge owner is the Port Authority of New York and New Jersey (PANYNJ). One of the PANYNJ project requirements was stated as follows:“Perform a minimum of two (2) separate axial compression load tests (one [1] in New York and one [1] in New Jersey) for each demonstration shaft of different size and construction methodology to verify the design assumptions and construction procedures. At a minimum, one (1) demonstration shaft is required to be representative of production shafts with a diameter within one (1) foot above or below the demonstration shaft diameter.Conduct a minimum of two (2) lateral load tests (one [1] in New York and one [1] in New Jersey) for each demonstration shaft of different size and construction methodology. At a minimum, one (1) demonstration shaft is required to be representative of production shafts with a diameter within one (1) foot above or below the demonstration shaft diameter.”"

Jan 1, 2016

By Giulia M. B., Ferruccio Cribari, Alessandro Bertero, Eliano Romani, Roberto Sorge, Francesca Casini

"The use of Artificial Ground Freezing (AGF) to form earth support and seepage control barrier systems has had applications worldwide. These cover a variety of construction problems, including the formation of frozen earth walls to support deep excavations, structural underpinning for foundation improvement, and temporary control of ground water in construction processes. An application of AGF during construction of Line C of Rome underground is described in detail.The new line “C” of San Giovanni metro station was constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and runs below the existing station. The underpass project envisages an Artificial Ground Freezing in order to create a structural and waterproof temporary cut-off suitable to the two new tunnels excavation, while keeping trains running in the safest possible condition. The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).Artifical Ground Freezing IntroductionNatural freezing occurs seasonally in many areas of the globe and can affect negatively the engineering performance of geotechnical structures; on the other hand, man-made freezing is a controllable process that can be used by civil engineers to stabilise temporarily the ground in order to support and/or exclude groundwater from an excavation until the final retaining and lining structures are constructed. Freezing and thawing of the pore fluid within soils involve complex thermal, hydraulic and mechanical processes that have significant mutual interactions. For example, phase changes of the pore fluid caused by temperature variations can modify the pore water pressure in the soil, which, in turn, can induce mechanical deformation. At the same time, any changes in the hydraulic and mechanical conditions affect the thermal processes by advection and changes of ice and water contents.An application of AGF which will be presented in the paper, refers to the construction works of Line C of Rome underground. In this case AGF was carried out to provide temporary support during excavation of the two Line C running tunnels directly underneath the existing S. Giovanni station of Line A, in the safest possible condition. In order to keep the trains of Line A operational during excavation, a temporary structure was installed and a real-time monitoring system was conceived in order to control the temperatures of the soil during freezing and the response of the structures of the existing station."

Jan 1, 2016

By Salvatore Fancello, Ferruccio Cribari, Amerigo Tanzi, Mauro D’Angelo, Massimo Lodico, Alessandro Bertero, Eliano Romani, Tommaso Gondolini, Fabio Giannelli

"The new metro line “C” entails the construction and rehabilitation of 24 stations and 21,5 km of metro line, 13 of which carried out underground; the new metro line will improve the transportation system of a congested city such as Rome.The new line “C” of San Giovanni metro station will be constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and will underpass the existing station. The underpass project envisages an Artificial Ground Freezing in order to excavate two new tunnels, while keeping trains running in the safest possible condition.In order to allow trains to regularly run to and from the existing station’s line “A”, a temporary structure for rail support, during excavation of the under-crossing tunnels, was installed and a real-time monitoring system was devised in order to control both soil temperature during freezing activities and the existing station’s behavior. The monitoring system has been one of the key to the success of the project.The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).THE NEW “C” LINE OF ROME’S METROThe world’s most complex and extraordinary Metro System is currently being built in the heart of Rome. Its underground route stretches underneath the most important monuments, churches and historical buildings.Rome’s Metro Line C is the longest urban underground railway in Italy and it is the first line in Rome to extend further east to the Great Ring Road, thus bridging the gap between the farthest suburbs and the Historical Centre. It is an original project, carried out mostly underground at a depth of 25/30 metres below road level."

Jan 1, 2016

By William Hawker, James Vaughan, Jeff Chen, Antony van der Ent

"Nickel agromining utilizes hyperaccumulator plants (“metal crops”) to extract nickel from low-grade soils, a process that yields high-grade nickel bio-ore. This feedstock is further processed into a range of nickel products. The bio-ore is relatively free of impurities that complicate the traditional processing of laterite nickel ores. In this paper, current primary nickel processing routes and proposed nickel bio-ore processing options are summarised. A novel pyro-hydrometallurgical route demonstrated at the laboratory scale is described. This process produces a precipitated nickel hydroxide product and takes advantage of the water-soluble basic compounds in the ash to minimise reagent requirements, thereby making it suitable for small-scale implementation in close proximity to the nickel farm. In this process, nickel is precipitated from the leach solution using the basic ash wash liquor. Leaching nickel from ash generated from open air burning requires strong acid and long residence times to obtain high recoveries due to its complex nature and distribution of nickel in multiple phases. This process can be improved by optimising the ashing process with respect to nickel leachability.INTRODUCTIONHyperaccumulator plants have the unique capacity to ‘biopurify’ and concentrate certain trace elements (e.g. nickel) from the soil into their biomass (Reeves 2003; van der Ent et al., 2015). Cultivating these plants as ‘metal crops’ by periodically harvesting and incinerating their biomass generates a high-grade bio-ore (Chaney et al. 1998; Li et al. 2003). This process is called phytomining or ‘agromining’ which is an emerging technology for extracting nickel from sub-economic resources (van der Ent et al., 2015). Potential near-term applications of the technology include implementation on land ahead of processing of the underlying ore-body (Willis 2015), as a mine-site rehabilitation strategy or as an alternative crop for farmers on land that is not suitable for normal food crops. In the longer term, nickel agromining could provide a significant supplement to the nickel supply chain. Critical to the success of agromining is effective bio-ore processing. Due to the unique chemical composition of this feedstock material, existing processes are not very efficient. Our current research efforts aim to develop new process options that overcome limitations of previously trialled routes. In this paper we summarise conventional nickel process routes and proposed new options for producing agromined nickel."

Jan 1, 2016

By Chang Wei, Fan Zhang, Zhigan Deng, Minting Li, Cunxiong Li, Gang Fan, Xingbin Li

Marmatite is an important resource of zinc, which exist in forms of high iron and high indium. In order to recycle the valuable metal from these ores, the testwork of simultaneous leaching on neutral residue mixed with zinc concentrate of high iron and high indium has been conducted. The primary objectives are to leach the zinc and indium remaining in the neutral leach residue as ferrite using acid, and to reduce the ferric iron in solution to the ferrous by zinc concentrate, thereby extracting the zinc and indium in the zinc concentrate. The results indicated that in the following conditions, mass ratio of neutral residue to zinc concentrate of 1:0.25, particle size of 74-58 μm, initial sulfuric acid concentration of 150 g/L, liquid to solid ratio of 8 L/kg, temperature of 90°C, reaction time of 4h, the leaching efficiency of zinc and indium were over 95%, nearly 90% Fe was Ferrous in the leaching solution. This process effectively extracted zinc and indium and converted Fe3+ into Fe2+ in solution, and simplified the traditional process of reduction after leaching.

Jan 1, 2016

By Michael Rehbock-Sander, Romed Insam

"INTRODUCTIONThe idea of building a summit tunnel under the Brenner occurred to the Italian engineer Giovanni Qualizza as far back as 1847. But it was to be another 160 years to pass before a base tunnel was to be built.In 1971 the idea of a tunnel at the Brenner was dusted off again. The UIC, the International Union of Railways, commissioned a study for a new Brenner railway with a base tunnel. By 1989 three feasibility studies had been drawn up which formed the basis for further planning of the Brenner Base Tunnel.This was the start of the planning activities. In 1994, the European Union included the Berlin-Naples corridor in the list of priority projects. Ten years later, Austria and Italy signed a State Treaty to build the Brenner Base Tunnel. In that same year, what is today the BBT SE was established.PROJECT DESCRIPTIONThe Brenner Base Tunnel (BBT) with a length of 55 km is the centrepiece of the Helsinki-Valletta Transeuropean Traffic Corridor from Finland to Southern Italy. The BBT tunnel system connects in the north with the Innsbruck station (Austria) as well as to the feeder routes in the Lower Inn Valley, and opens to the south with the projected new line in the direction of Verona (Italy). The tangible design efforts have been underway since 1999; the start of construction of the first section was in the year 2007. The project is financed by the Italian and Austrian governments (each 30 %), as well as by the European Union (40 %).From 2027 onwards the Brenner base tunnel, including the existing lines connected with it, will carry a daily average of 330 trains (approx. 80% cargo trains and 20% passenger trains)."

Jan 1, 2016

By Maurizio Siepi, Bruno Vingiani, Claudio Asioli

"The article describes an emergency rehabilitation intervention executed at Buyo Dam, in Ivory Coast, to intercept a significant water seepage occurring through the foundation of this zoned earthfill retaining structure constructed in the late Seventies. To solve the problem, a 800 mm thick, 400 m long impervious cut-off wall (COW) was constructed on the right side of the embankment, operating from the dam crest and with the reservoir almost at its maximum level. The use of an innovative pre-mixed self-hardening grout, with a target hydraulic conductivity coefficient (k) lower than 10-9 m/s, was considered the only way to match the tight working schedule and the strict requirements for the filling material of the COW.Presentation of the Hydroelectric Scheme of BuyoThe hydroelectric scheme of Buyo, located at 6°14’28” N 7°20’45 W on the Sassandra River, in Ivory Coast (Figure 1), was built in the late Seventies for agriculture and power generation. With a reservoir of 8.3 billion m3 and an installed power capacity of 165 MW, enough to supply electricity to 111,000 homes, it represents an installation of great significance for this West African country."

Jan 1, 2016

By Fatima-Zahra Houmymid, Elena Chiriotti, Mahdi, Samy

"The Greater Paris projects involves the creation of a 200km extension of the actual public transport network on the close outskirt of Paris. In 2011, SYSTRA has been awarded the Engineering studies of a 20km underground section in the densely urbanized southeast quarter of the Parisian suburb. In order to both guide the TBM technology choice and identify and mitigate the risk due to soil settlement during tunnel boring, several analysis have been carried out and integrated into a Geographical Information System to share and manage this risk during the successive design phases of the project. The geological context‘s complexity and the Owner‘ requirements have led to the necessity of using an innovative analysis approach, leveraging both the numerical modelling analysis’s accuracy and the analytical method‘s ease of programming and implementation in a GIS, by the mean of the calibration of the analytical approach’ parameters on the FEM results.INTRODUCTIONThe Greater Paris Transport Project foresees the extension of the actual public transport network to the close outskirt of Paris through the extension lines 11 and 14, the creation of a circular new line around Paris - line 15 completed by lines 16 and 18 linking developing territories - and line 17 to Roissy-Charlesde- Gaulle airport.The SOCIETE DU GRAND PARIS (SGP) is the public institution that promotes this project and awards SYSTRA as Engineering for the 15th Line southeast section.Line 15th – South-East sectionIn 2011, the Owner SGP (SOCIÉTÉ DU GRAND PARIS) awarded to SYSTRA the preliminary and detailed design of a 20km-long underground section of Line 15, between the stations of Villejuif-Louis-Aragon and Noisy-Champs. The double-track, single-tube tunnel has an inner diameter of 8.5m (about 9.8m excavated diameter, 75m2 excavated cross-section). The tunnel is inserted in a densely urbanized context."

Jan 1, 2016

By Rachael M. Fischer, Daniel J. Woeste, Terence P. Holman

"A new 50 MW biomass renewable energy power plant was planned for construction in southwestern Georgia. The original foundation design consisted of very conservatively designed H-pile groups with vertical and battered piles to carry the axial and lateral loads. The authors conducted a testing program to value-engineer the foundations with the goals of increasing the working axial pile resistance and reducing or eliminating battered piles. Seven test piles were installed and dynamically monitored with a Pile Driving Analyzer (PDA). Two lateral load tests and one tension load test were conducted. The results of our testing program allowed the project team to: (i) increase working pile resistances by factors of 1.5 to 2, reducing the total number of piles by more than 30%, (ii) eliminate the battered piles, and (iii) lessen overall project risk. Poor communication and documentation in a critical area of the site required some piles to be spliced and re-driven after additional PDA testing, establishment of new driving criteria, and consideration of longterm soil setup. This case study emphasizes the economic and risk reduction benefits of a design phase testing program, and the need for consistent communication between parties in the field.INTRODUCTIONA new 50 MW biomass renewable energy power plant (Plant) was planned and constructed in southwestern Georgia. The Plant converts clean wood-based and paper-based waste from existing forestry and pulp operations, waste timber, and maintenance operations into steam that is used by an adjacent manufacturing facility. The Plant also generates electric power with limited greenhouse or particulate emissions for use by a local utility provider.The project site (Site) is located in Dougherty County, in the Coastal Plain physiographic province of Georgia; an area of known karstic activity. Specifically, the Site is underlain at depths of 30 to 45 ft by the Ocala Formation, a light-colored fossiliferous limestone of the Eocene era. According to Watson (1981), the Ocala Formation is 125 to 200 ft thick in the vicinity of the Site and increases in thickness to the southeast. Due to differential weathering, this formation is characterized by an irregular upper surface that transitions from sandy clay/clayey sand into a dense to very dense silt and fine sand locally referred to as limestone. This subsurface stratum is most relevant to the foundation design of the Plant."

Jan 1, 2016

By Jens Classen, Martino Gatti

"GENERAL PROJECT DATAThe Sparvo Tunnel is part of the “Variante di Valico” project, a new 65km (40mi) highway link between Bologna and Florence, designed to renew the existing A1 route which connects Bologna and Florence. It is composed of 2 x 2,5km (1,55mi) twin tunnels excavated inside a complex geological context, characterized by the presence of a series of surface landslides and methane gas.The inclination is 2,6 % and the minimum radius is 1.400m (4.600ft). The two tunnel tubes were excavated by a 15,6m (51ft) diameter EPB-TBM from summer 2011 to summer 2013. The internal diameter of the concrete lining is 13,6m (44,5ft), made up of precast concrete segments 2m (6,5ft) long and 70cm (28”) thick, being the largest and heaviest segments ever produced. Excavation went smooth apart from initial problems concerning clogging problems and a main bearing damage of the TBM, which are discussed in a further paper during the congress. No structural damage was observed until the end of the TBM drives.SITE OBSERVATIONS DURING THE POST-EXCAVATION PHASEThe first evidence of the stress state of the segmental lining appeared on November 20, 2013 inside the northern tube (1st drive). Ring No. 884 showed obvious signs of overstress, resulting in spalling and crushing of the concrete, and the subsequent bending of the reinforcement, as visible in figure 1.At this time the tunnel invert was already partially backfilled, and construction traffic was running through the tunnel. First safety measures included closing of the tunnel, and initial measurements of the displacements."

Jan 1, 2016

By Wayne S. Smith, Erik James, Jose R. Gomez

"Soil mixed seepage cutoff walls are increasingly being used in levee and dam modification projects nationwide. An important aspect of their overall quality depends greatly on the language included in the specifications. Depending on the method (e.g. vertical axis auger mixing, cutter soil mixing, or trench mixing techniques) the specifications are a blend of prescriptive and performance based contract language with differences in element construction, element connections, quality control/quality assurance, and work area restrictions. Many of the existing specifications were initially developed by contractors in whole or in part, and can contain restrictive provisions favoring the authoring contractor. In response to these challenges, basic soil mixing fundamentals were revisited and recent lessons learned incorporated, resulting in the development of a new specification for soil mixed seepage cutoff walls that provides adaptability for the various construction methods. The new specification addresses quality control, quality assurance, equipment independence (elimination of restrictive contract language), rig instrumentation.INTRODUCTIONSoil mixing has been used in the construction of seepage barriers for over 30 years. Most soil mixed project primarily use the wet-rotary-shaft, wet-rotary-end or wet-vertical panel methods (reference FHWA Deem Mixing Manual Figure 137). One of the first major soil mixing seepage barriers was constructed in the Jackson Dam in Wyoming. Since then the use of soil mixing for seepage barriers has increased significantly and this specialized domain of construction which was solely procured by RFP methods, is now increasingly being specified in projects issued for bid. The Bid documents require more careful specification writing than RFP methods because the RFP methods allowed detailed proposals by the contractor. Therefore the development of soil mixing specifications began with contractors preparing the specifications. This paper addressed some of these issues, and proposes methods to address these resulting concerns. The resolution of these issues considers several aspects: 1) Assessment of binder injection, 2) Evaluation of mixing index, and 3) Verification testing."

Jan 1, 2016

By Andrew R. Klaetsch, Peter W. Deming

"The Washington Avenue tunnel in Kingston, NY was completed in 1912 to convey combined storm water and sanitary sewage. Over a mile in length, the tunnel was driven almost entirely in bedrock, with the exception of an approximately 170 foot long brick arch segment constructed in soil. About 90 years after the tunnel was put into service, persistent subsidence problems and sinkholes were observed in Washington Avenue above the shield-driven soil tunnel segment, eventually causing the important traffic thoroughfare to be closed. Subsequent tunnel inspections revealed a breach in the brick arch and a significant volume of fine soil within the tunnel. A two-phase remediation program was implemented to control seepage, reduce soil migration, and remedy sinkhole problems. The first phase included in-situ soil densification by vibratory pile probe driving to improve density in shallow sandy soil loosened by ground loss. The second phase included installation of a continuous soilcrete arch structure over and alongside the tunnel, extending to rock or compact glacial till and spanning the length of the soil tunnel segment. Overlapping vertical soilcrete columns were installed through interlayered sandy and clayey silt by jet grouting to form a continuous arch structure, using grout parameters verified by full scale field testing.PROJECT BACKGROUNDThe Washington Avenue tunnel in Kingston, NY (Figure 1) was completed in 1912 to convey combined storm water and sanitary sewage to Rondout Creek by the Board of Water Supply of the City of New York. The tunnel is over a mile in length and constructed primarily in rock. Contract documents indicate the tunnel was designed with a horseshoe shape at least 3 ft wide and 5.5 ft high."

Jan 1, 2016

By Frank Haehnig, Harald Krenn, Harm-Christoph Claassen

"The Wadi Dayqah Dam Water Supply Scheme represents one of the most important projects implemented by the Sultanate of Oman to ensure sustainability of water resources. The principal components of the project comprise two dams to impound the Wadi Dayqah, to store and supply drinking water to the local area and to Muscat, the capital city of the Sultanate.The Main Dam with a central spillway is a RCC Gravity Dam with a maximum height above foundations of 75m, crest length 400m; the Saddle Dam is a rockfill dam with central clay core, max height above foundations is 49m and crest length 360m. During construction of the Saddle Dam a key trench was excavated to 10m depth and filled with compacted clay connected to the central core of the embankment. Grouting utilizing cement grout was performed as a single line grout curtain prior to each filling operations. Both Dams are founded on soft Siltstone, Claystone, Sandstone and inter-bedded harder limestone.After construction of the Saddle Dam, once water was in the reservoir it became evident in early 2010 that some seepage was occurring apparently from the right abutment. This seepage became more marked when the reservoir first filled to discharge over the spillway in June 2010. In order to reduce the seepage, additional sealing works by drilling and grouting of a three row curtain up to 80 meter target depth were initiated to supplement the existing single row curtain. Part of this project for the sealing works has also been to drill additional investigation holes to provide more information and confirm extend of the additional sealing works and its limits.Züblin Ground Engineering was awarded the Additional Sealing Works Contract. Whilst Equipment was on Site, the opportunity was taken to carry out drilling and grouting on the Left Abutment of the Main Dam to reduce seepage through that abutment and to install additional standpipe piezometer for future monitoring of seepage patterns.Work on this Contract started on site in January 2013 and was substantially completed in January 2015.At the time of Tender Züblin Ground Engineering propose and Alternative Design in the form of a Secant PileCut-Off Wall, 85m long to a depth of 40m with additional drilling and grouting below the foot of the cut-off which was then included in the contractual scope."

Jan 1, 2016

By Lisa R. Papandrea, David Chen, Walter E. Kaeck

"Construction of the University at Buffalo’s new School of Medicine and Biomedical Sciences (UB-SMBS) required excavation in variable ground to a depth of more than 40 ft adjacent to the NFTA Metro subway and Allen Street Station. Complicating the building design and construction, the new medical facility incorporates the at grade Station entrance building, requiring a combination of temporary and permanent excavation support structures, a complex sequence of ground support installation, and a mix of shallow and deep foundations to accommodate the large floor spans and concentrated column loads introduced by building over and adjacent to the Station entrance. Excavation and foundation construction was challenged by a stratified soil profile with interlayered and sensitive sands, silts and clays and complicated groundwater regime with perched and regional water tables. Efficient construction required ongoing coordination between the design team and contractor, careful field observation, and construction monitoring in several facets of below grade construction. This paper describes the design and construction of excavation support structures and foundations to manage the variable ground, congested site conditions, and complications of building adjacent and above an active subway station. Use of site instrumentation and monitoring data to provide guidance in construction when unanticipated field conditions arise is illustrated. Lessons learned in installation and sequencing of excavation support, groundwater control and foundation construction are also discussed.INTRODUCTIONUniversity at Buffalo President Satish K. Tripathi heralded the new School of Medicine and Biomedical Sciences (UB-SMBS) as a future linchpin of UB’s downtown campus that will revitalize the area and enhance western New York’s emerging bio-sciences corridor. The $375 Million, 628,000 square foot, eight story building with two basements is expected to house 2,000 faculty, student and staff allowing UB to increase class size from 140 to 180 students. It will be constructed above the Niagara Frontier Transportation Authority’s (NFTA) Allen Street Station, creating a direct connection to Buffalo’s light rail system. The 200 ft x 400 ft site is bounded by Main Street, High Street, Washington Street and the Roosevelt Apartments and adjoining parking lot at the west, north, east and south respectively, as shown in Figure 2. Groundbreaking for the new building was in October 2013 with the facility scheduled to open in early 2017."

Jan 1, 2016

By Bartho J. Admiraal

"As part of the Schiphol-Amsterdam-Almere project, the largest aqueduct in Europe is being built in order for the A1 motorway to cross the Vecht River. The A1 consists of 12 lanes and the total width of the aqueduct will be 65 m (213 ft). The total length of the structure will be 620 m (2035 ft). Speed of construction is essential for the DBFM-contract, which forms the primary reason for choosing a building method with a horizontal water retaining barrier created by low pressure grouting. After final checks on the water tightness of the silica based layer (softgel), excavation to a depth of approximately 12 m (40 ft) below the water table could be started in order to build the aqueduct.This paper presents a new approach for the calculation of the required grout volumes needed to ensure a “softgel” layer without gaps or holes. The approach applies measurement of deviations due to execution aspects in a probabilistic model. With this model, one is able to study the effects in a field application, i.e. multiple rows of grouted spheres. The results are visualized in order to analyze the risk of holes more easily. It is evident that the existence of a hole means a major leakage. By completing multiple runs, the strategy for grout volumes can be adjusted to minimize this risk.INTRODUCTIONThe Dutch Department of Waterways and Public Works invests over € 4 billion between 2012-2020 to increase the capacity of 63 km (41 mi) motorways of one of Holland’s major corridors. The A1/A6 will be transformed over a distance of 20 kilometers (13 mi). Near Muiden, the current drawbridge on the A1 for crossing the Vecht river will be replaced by a new aqueduct to be located slightly south of the existing bridge."

Jan 1, 2016

By Kevin P. Gleckler, Steven C. Highfill

"Escalators to access platforms for the Second Avenue Subway Station at 72nd Street in Manhattan are to be installed in the basement of an existing 19-Story residential building. The escalators, which extend below the existing building foundations, require excavation of an inclined rock cavern up to 80-feet deep. Underpinning of columns within the 19-story building as well as a stone masonry party wall and columns for an adjacent 5-story building was completed prior to excavation of the rock cavern to ensure structural stability.This paper will discuss the analysis and design of the underpinning system, the installation and load transfer procedures and the cavern excavation immediately below. The underpinning system was subject to very strict deformation limits and to electronic monitoring prior to and throughout the load transfer and construction process. Key details such as the load transfer mechanism between the reinforced concrete column and the temporary structural steel underpinning frame will be discussed. The challenging rock excavation process will be described which utilized conventional equipment and pattern drilling with Damite rock splitting mortar.INTRODUCTIONPhase 1 of the Second Avenue Subway is being built by MTA Capital Construction (MTACC) to improve subway service on the east side of Manhattan. Entrance 1 for the 72nd Street Station of the Second Avenue Subway is located on the east side of 2nd Avenue at the corner of E 69th Street in New York City. Access to the station mezzanine, approximately 80-feet below grade, is designed to be routed through the basement of an existing 19-story residential building. From the sidewalk, stairs and escalators within the width of sidewalk connect the riding public to a basement level mezzanine, which turns into the building at roughly 16 feet below grade (Fig. 1). Riders then connect to three long escalators to arrive at the station mezzanine. The escalators are to be installed within an inclined and arched cast-in-place (CIP) concrete lined rock cavern (Fig. 2). Construction of both the entrance into the basement and the escalator cavern require the transfer of columns within the 19-story building. Excavation of the escalator cavern also impacts the foundation support for columns and a load bearing party wall for the 5-story residential building immediately to the north. Two stages of load transfer were used at each location. The Stage 1 transfer used a temporary underpinning system to unload the current structure which allowed for construction of the permanent transfer girders. Stage 2 transferred the load from the temporary system to the permanent transfer girders."

Jan 1, 2016