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By Christopher J. Pacitto

This paper presents a case history of an engineered, monitored, and tested program that provided an effective and satisfactory basis for the completion of pile foundations for Twin Dolphins 1 at La Peninsula Condominiums located in the Isles of Capri in southwest Florida, U.S.A. An 8-story building (withl-story parking underneath) along with recreational facilities (such as a swimming pool and tennis courts) had been planned for final construction. Following an evaluation of various foundation alternatives, a precast prestressed concrete (PPC) pile-supported system was selected. The building foundations were designed for pile capacities of 445kN (50 tons) and 890kN (100 tons) in compression and 133kN (15 tons) in uplift. A test pile program was performed to provide site-specific pile driving data, verify design assumptions, determine production pile lengths, and evaluate pile driving criteria. A total of 24, 356 mm (14-in.) square, 19.8 m (65 ft) PPC concrete piles were driven and dynamically load tested utilizing a Pile Driving Analyzer (PDA) within the building limits. Dynamic monitoring during probe pile installation and restriking was performed to estimate the ultimate capacity of the piles and to evaluate driving stresses during installation. CAPWAP analyses were preformed on PDA data to better estimate pile capacity, resistance distribution, and predict pile freeze (increase in pile resistance with time) and thus optimized the production pile lengths. Upon completion of probe pile installation, 12 of the probe piles were tested using the Pile Echo Tester (PET) function of the Pile Integrity Sonic Analyzer (PISA). PET testing was performed to evaluate the integrity of piles which had exhibited high driving stresses during PDA testing. Information gathered during the probe pile driving program was effectively utilized as part of the overall quality control program to install a total of 539 PPC piles (including 24 probe piles) within the building limits at the project site to depths ranging from 9.1 to 19.8 m (30 to 65 ft) below the existing ground elevation as part of the foundation support system. Prior to installation of probe or production piles, a termination criterion was established using 1-dimensional wave equation analyses in addition to the design pile embedment requirement. The predicted pile capacities compared very well with the capacities from the CAPWAP analysis for probe piles. Use of geotechnical instrumentation and PDA assisted technology enabled each foundation support element to be constructed to its optimum capacity and at optimum cost. Furthermore, by using PDA the consultant was able to quantify a difficult to measure geotechnical phenomenon termed "pile freeze" which eliminated costly overdriving and unnecessary splicing of piles.

Jan 1, 2002

By Patrick E. Durnal, Henrik Dahl

"A joint venture of Ben C. Gerwick Inc., Sverdrup (now Jacobs) and DMJM (now DMJM + Harris) designed the $779 million seismic upgrade of the Richmond - San Rafael Bridge over the San Pablo Bay in the San Francisco Bay Area and provided construction support to Caltrans. Construction of the marine foundation retrofi t was completed by a joint venture of Tudor Saliba/Tidewater/Koch-Skanska and their subcontractors: Pomeroy Precast Construction, AGRA Foundations, Dutra Construction and Vortex Divers. Construction management and inspection was performed by Caltrans with the support of various consultants. MARINE FOUNDATION RETROFIT SCOPEThe retrofi t design of the submerged foundations included:??A total of 476 tension and compression micro piles (290- 1140 kips or 1290-5071 kN) installed through cored holes through the underwater bells at 31 pier locations??Fourteen 126/150/164 inch (3.20/3.81/4.17m) diameter CISS (Cast-in-steel shell) concrete shear piles (1160- 2660 kips or 5160-11832 kN) installed through new precast concrete pile cap extensions??Twelve CIDH (Cast-in-drilled-hole) shear piles (1060- 2130 kips or 4715-9475 kN) with 150 inch (3.91m) diameter steel shells to top of bedrock and 30 ft (9,14m) long and 11 ft (3.35m) diameter rock socket installed through new precast concrete pile cap extensions The specifi ed post bid test boring revealed deeper bedrock at one pier location allowing deletion of the rock socket. Thus 15 CISS and 11 CIDH shear piles were installed at 11 pier locations - 9 piers with 2 piles and 2 piers with 4 piles. Cut off elevations for the shear piles ranged from 46 ft to 60 ft (14.0m to 18.3m) below mean sea level and cut off for the micro piles was 8 ft to 46 ft (2.44m to 14.0m) below mean sea level. Almost all foundation retrofi ts required work under limited headroom conditions. Underwater construction connections required innovative design details and construction techniques for each pile type. The 11 piers had 22 precast concrete pile cap extensions installed in pairs and connected by either tremie concrete closure pours or by large pipe struts. The precast pile cap extensions were strapped underwater using large steel bands wrapping around the belled piers with grouted annulus. The precast pile caps were founded with 14 inch (355mm) diameter steel pipe piles, which were either support piles or seismic tension and compression piles. The seismic piles were connected in grouted corrugated steel pipe sleeves cast into the new concrete pile caps."

Jan 1, 2007

By Antonio A. Cristóvão, Alexandre Pinto

"Abstract Deep foundations of buildings using driven ductile iron micropiles TRIM solutions, leads to recognized advantages, from technical, schedule and economic points of view. High production rates together with the possibility of using conventional equipment, duly adapted, confer this solution a high versatility.The aim of this paper is to describe the main design criteria adopted for the foundations of the Church ""Nossa Senhora dos Navegantes"" building in Lisbon - Portugal. In addition, results of a full scale load test carried out at site are presented, confirming the adequacy of the solution to the geological and geotechnical scenario, which is characterized by the proximity of the Tagus River Basin as well as the presence of heterogeneous landfill material and alluvial layers of soft clay (muds).1. INTRODUCTION Located on the right bank of the Tagus River, in Lisbon, the new Church building of ""Nossa Senhora dos Navegantes"", patroness of fisherman and navigators, with three or four upper floors, is surrounded by a school and by new residential buildings.The Tagus River basin is known by its alluvial soft soils, achieving, in certain areas, more than 50m meters depth, challenging the construction of new facilities due to the significant unfavorable geotechnical conditions.With a modern an unusual architecture, allusive to the ships used by the Portuguese navigators, the building has a reinforced concrete structure, with one basement and three upper floors. A bell tower with about 40m high, emerging from the structure, marks the landscape with the presence of this religious building (figure 2).For all the reasons previously described, geotechnical engineers play a crucial role on the design of valid foundation solutions, from both technical and economic point of view. Ideally, the solutions adopted should be supported by full scale load tests, performed at site, so that design assumptions could be verified and adjusted on time."

Jan 1, 2014

By James A. Mason

The State of California has instrumented numerous buildings, bridges, and dams throughout the state with earthquake recording devices. These accelerometers are strategically placed to measure the response of the structure to a specific seismic event. This comprehensive program enlightens the field of seismic engineering after each earthquake. The Office of Strong Motion Studies, California Strong Motion Instrumentation Program, a sub-branch of the Division of Mines and Geology, provides a professional service unequalled in the world. Within hours of a local earthquake, a preliminary report with the epicenter / hypocenter, structural damage, and time history records are available to all interested parties. The included partial report in the appendix, see section 5.1, is one of the reports that C.S.M.I.P. produced after the Loma Prieta Earthquake of October 17,1989. The diagram on the cover is even of interest. This is a small portion of San Francisco. The values on the diagram are the recorded maximum horizontal ground accelerations at that location in the city. For example, the acceleration at Yerba Buena Island was 0.06g. (The "g" refers to the acceleration of gravity. Thus, a 0.06g acceleration refers to the force, F=m*a, that the structure would experience. For this case, the force would be six percent, 6 % , of the mass of the structure.) Yet, directly on the other side of the Bay Bridge, at Treasure Island, the acceleration was 0.16g. Yerba Buena Island is a natural island composed of hard granular material. Whereas, Treasure Island is a man-made island of imported filled. Here one can see the absorption / transmission difference between hard material, which interact with short seismic wavelengths, and soft cohesive material, which interact with long seismic wavelengths.

Jan 1, 1993

By Robert C. Simpson, Ghada S. Ellithy

"There are several methods for estimating the axial capacity of drilled shafts installed in coarse-grained soils. Most methods estimate the ultimate capacity for side friction and tip resistance. Design capacity is then calculated by applying a resistance factor to the ultimate capacity. In reality, however, ultimate resistance may not be mobilized except after a significant displacement that is not structurally tolerated in either compression or tension modes.A full- scale load test is the best way to obtain the load settlement curve for a drilled shaft, especially in soil formations where accurate estimation of soil frictional properties from a field investigation may be difficult. This paper presents the results of a static, axial, compressive bi-directional load test, using the Osterberg method (O-cell test). The test was designed so that the shaft above the O-cell would move up and the shaft below it would move down when loaded. At the start of the test the concrete around the O-cell is fractured generally on a plane near the bottom of the cell.The test was designed to validate the design capacity of drilled shafts embedded into the Vashon recessional outwash (Qvro), which is a glacially derived sediment consisting of thick deposits of cobbly sand and gravel relatively free of silt and clay found in the Seattle, WA area. The test shaft consisted of a 2.5- feet (0.75 m) diameter drilled shaft. The test shaft was installed to a depth of about 47 feet (14.3 m) into this formation. A maximum load of 437 kips (1.95 MN) was applied during the test, in each direction. The maximum load was attained at upward and downward displacements of less than 0.1 inch (2.5 mm), respectively.Although the load test did not yield ultimate values, the results are compared to the design assumptions using methods adopted in the FHWA and AASHTO guidelines, which verified the adequacy of the design assumptions. We conclude that more emphasis is needed in the prediction of the service loads and corresponding mobilized displacement that may lead to a more cost effective design. It is also clear that more testing to higher loads could lead to more efficient designs on specific projects and generally as data is added to the local knowledge base."

Jan 1, 2015

By Raymond E. Sandiford

"The redevelopment of the World Trade Center (WTC) provided an opportunity for the Port Authority of NY and NJ to complete a long sought underground connection between all of Lower Manhattan’s transit lines, the World Trade Center and the World Financial Center (WFC) (Figure 1). Creating this connection was a challenge because the WFC lies west of the heavily trafficked Route 9A, also known as West Street. The previous connection was a bridge that required pedestrians to make significant level and directional changes to navigate the crossing. The positioning and elevation of the Route 9A pedestrian tunnel was established to provide pedestrians with a clear, single level, climate controlled corridor from the new WTC Transit HUB to escalators leading into the WFC Winter Garden.As the most direct link to the WFC, tens of thousands of people a day will use the pedestrian corridor. To accommodate this large number of pedestrians and provide an obstruction free passage, the tunnel has a clear width of 50 ft (15.2 m). Although only 250 ft (76.2 m) long, that short length presented many technical challenges.Here I describe how the challenges were overcome during the construction. However, some of the truly problematic issues arose from coordinating the phasing of this project with adjacent construction activities at the WTC, the reconstruction of Route 9A, and the WFC’s redevelopment program. The limited access to the excavation areas and confined site logistics were further complicated by having to maintain six lanes of traffic on Route 9A at all times. The efforts were so intertwined that, well into the underpass construction, the Port Authority Construction Department decided to merge a portion of that work into the WFC redevelopment."

Jan 1, 2012

By Brian D. Barkauskas, Terence P. Holman

A major combined nuclear and coal-fired power plant, located in on the western coast of Florida has undergone multiple upgrades in recent years to increase power output and enhance environmental controls. Construction of new elements within the existing plant structure required working in highly congested conditions and heavy crane lifts with large picking radii. The largest crane pick involved the use of an 1800 metric tonne capacity Mammoet PTC ring crane for a single long-radius, high altitude lift of a precipitator unit. Original bid tender documents had called for drilled shaft foundation support, but the presence of many critical utilities and unfavorable access for cost effective construction led specialty contractor Moretrench American Corporation to propose an alternate micropile foundation on the basis that high capacities could be achieved in the weak limestone geology and that the smaller size of micropiles would allow for more surgical installation in the utility-congested areas. This case history describes the design and construction of seventy three (73) high capacity micropiles for the value engineering alternative and the crane foundation for this critical lift. Each micropile was founded in a competent dolomitic fossiliferous limestone unit at typical depths of 23 m below existing ground surface. Strain gauge instrumented load testing was used to validate the geotechnical design parameters in the weak limestone bedrock and resulted in the finding that the entire test load was being carried in the upper half of the bond zone. Construction of the production micropiles required numerous relocations due to utility conflicts and local reanalysis and redesign of the 1.2 m thick reinforced concrete ring beam cap. Crane foundation performance was satisfactory and the effective life of this temporary foundation was only 6 months before decommissioning and demolition.

Jan 1, 2017

By John G. DiGenova

The Allwell Center Ice Arena at Plymouth State University, Plymouth, New Hampshire is located in the flood plain of the Pemigewasset River. To maintain the arena near the level of the surrounding area, foundation design required use of uplift elements to resist hydrostatic loads caused by frequent flood conditions. Soils beneath the arena consisted of very loose to medium dense alluvial deposits overlying thick glaciolacustrine deposits. Bedrock was encountered at depths of 115 feet (35 m) or more. A mat foundation with a sealed building system was developed for the arena to guard against flood events. Several alternatives were investigated to provide uplift capacity for the mat foundation, including the Rammed Aggregate Pier® (RAP) system, driven precast-prestressed concrete piles, driven H-piles, and deep drilled soil/rock anchors. Evaluations indicated that the most cost effective uplift solution was a tension RAP system that developed uplift resistance in the shallow alluvial deposits. A total of 344 55-kip (245-kN) capacity RAP elements were required for the project. The RAPs were designed to resist tensile loads using threaded steel bars. Dual corrosion resistance was provided to the uplift elements by including sacrificial steel and galvanizing the oversized bars and connection plates. A pre-construction test program was conducted on RAP elements drilled to a depth of approximately 25 feet (7.6 m) and installed using various shaft construction procedures and materials. Ten test piers were constructed and six were tested to verify that the piers could resist 200 percent of the design load with measured deflections of less than 1 inch (25 mm). The RAP system also provided improved bearing conditions for the perimeter wall and mat foundations by densifying and stiffening the upper alluvial soils.

Jan 1, 2011

By D. Y. Peng

A Large Sub-structure with open top of S.Y.P. float line requires a 90m x 50m in plan and 13m-deep excavation in soft soil, Shanghai. The geological conditions in site are rather severe. The technology specifies that no permanent braces nor partition walls are allowed to be constructed inside. After a series of discussions the scheme of semi-gravity type cellular D-walling without any braces or earth anchors is finally adopted and successfully executed by SFEC. This paper deals with the technical problems in the design, construction and in-situ monitoring we met with in this difficult project.

Jan 1, 2010

By W. J. Grose

The Embankment Place office development over the platforms of Charing Cross Railway Station in London has presented many interesting and unusual problems to the engineers involved with the project. The main structure is supported on widely-spaced columns which penetrate the station platforms and underlying vaults, calling for high capacity foundations built in severely restricted spaces. Hand-dug underreamed piles were chosen. Whilst a conventional design approach was taken to size the piles, a detailed appraisal of ground movements was made to explore the effects of the new building loads on the existing foundations, not only beyond the site perimeter but also those amongst the new foundations. Before construction of the pile proper could take place, it was necessary to sink a caisson through the upper unstable and water-bearing soils. This being identified as a high-risk item, a full-scale trial was carried out prior to embarking on the main works. The twenty-one hand-dug piles were 2.5m diameter, over 30m deep and belled out to between 4.5m and 6.6m.

Jan 1, 1989

By Sun Shao Xian

The Port of Shekou is situated at Shenzhen Bay on the east side of the Pearl River estuary. Geological condition of the site is quite complicated. On top of the sea bed, there is a layer of soft silt 8 - 14 m thick. Under the soft silt, there are intercalated layers of sand, silt and clay. Average surface elevation of the underlying undulatory weathered bed rock is about - 20 m, with a variation of about 10 m. In certain locations, the weathered bed rock is covered with a layer of silt 3 - 4 m thick. This paper gives brief account of three types of wharf structures which are of particular interest, constructed in the last few years: (A) Platform type wharf structure with frontal sheet piling and steel raking pile in the rear; (B) Relieving Platform type structure with steel sheet piling and inclined anchoring HP pile ; (C) Steel pipe pile row supported apron added to a marginal quay. Average construction time of a deepwater berth is about six months.

Jan 1, 1991

By Q. M. Huang

In 1979 our company undertook the project of infra-structural work of White Swan Lake Hotel, (International class ) Guangzhou. Visit to the site showed that it was situated at the riverside, covering an area of 54,000 M2 with 30,000 M2 of which reclaimed from Pearl River. The material used for reclamation was black sand which was dredged from the nearby riverbed. The sand had the properties of high permeability and very low internal friction. The basement of the building was 6.2 m below ground level and 3 m lower than the riverbed. Apart from the pile foundation, a diaphragm wall was to be constructed prior to the commencement of excavation work for basement. A feasibility study was carried out to determine the method of construction which would maximize utilization of the plants and equipment that were available in the execution of the aforesaid foundation works. This report concerns only the construction of the diaphragm wall and the performance of the plants employed. A detailed delineation of the construction method is herein discussed

Jan 1, 2010

By Shaw-Shong Liew

This paper presents the design concept using floating piles to support 2500Ton oil storage tanks on a very soft alluvial clayey soil of about 40m thick in Riau Province of Sumatra, Indonesia. The floating piles of various penetration lengths were designed to support seven numbers of such storage tanks seating on a 20m diameter and 500mm thick reinforced concrete (RC) circular raft. The pile points have been strategically located at the RC raft. Varying pile penetration lengths have been designed to minimize the angular distortion of the thin RC raft and the out-of-plane deflection at the tank edge. Vibrating wire strain gauges were installed at different levels inside the ø350mm prestressed reinforced concrete piles to measure the load transfer profile during the static load tests and water-loading test. The installation and interpretation of the instrumentation are described and discussed. Boreholes, in-situ tests like piezocones, vane shear tests and standard penetration tests, and laboratory testing were carried out to obtain geotechnical parameters for the pile designs. Static load tests were also carried out on the spun piles of varying lengths of 24m, 30m and 36m respectively. It has been demonstrated that the floating pile system can be a cost effective design to support heavy structures on very soft compressible deposits with satisfactory performance. Finally, the design concept validated with the results of instrumentation is discussed.

Jan 1, 2002

By Edward Jacobsen

The Oak Creek Power Plant in Oak Creek, Wisconsin is currently undertaking an expansion project. In order to supply cooling water to this facility, a 27' (8.2m) diameter tunnel will be bored, in rock; to connect to 4 vertical Intake shafts located approximately 1.5 miles (2.4km) offshore in Lake Michigan. In 2004, Case Foundation Company was awarded a lump sum contract to Install these intake shafts. When complete, the plant is expected to circulate upward of 2 billion gallons per day (7.5 billion liters) through this system. Two shafts were drilled in a (shortened) construction season in 2005 and the remaining 2 shafts and 4 liner assemblies were completed in 2006. Future connection to the tunnel, in 2007, will be accomplished by mining upward to reach the lower portion of each liner and then removing its internal bulkheads to permit the flow of the lake water into the tunnel.

May 11, 2007

By Thomas Passlick

By means of further developed machines and techniques and with growing experiences in jet grouting, the challenge of this building method becomes more and more complex. To keep the concerning risks as low as possible, the requirements on the quality assurance continuously in­crease. The construction of a 37.0m deep seated slab for the Amsterdam metro station Vijzelgracht in marine clay represents such a complex task. This paper summarises the required measures of quality assurance. In particular a new hydraulic measuring device is introduced with which it was possible to detect the column diameter of 2.6m at a depth of 37.0m during the production process and with a very high accuracy.

Jan 1, 2006

By Antti J. Perala, Teemu J. Yli-Kovero

"Efficient use of land is constantly requiring more underground construction. Minimized execution time and disturbance to surroundings and nearby structures are essential benefits for all construction techniques. To meet the demands of a modern construction project, suppliers have to be able to provide high-quality and tailor-made products just on time. RD pile wall is a retaining wall based on drilled steel pipe piles which are connected to each other with special interlocking profiles. RD pile wall is a solution which enables penetration of overburden soil, dense fill layers including stones and boulders, and embedding into the bedrock in one single operation. Several test installations and laboratory tests have been made to develop the system and to test and improve the water tightness of the wall. Beside these tests, RD pile wall has also proven its reliability in almost 70 projects. Largest project so far has been Pasila Tripla project in Helsinki, Finland. A permanent retaining wall with surface area of 18,000 m2 (193,750 ft2), excavation depth of 21 m (68 ft) and over 17 m (56 ft) of water pressure was made with 711 mm (28”) and 406.4 mm (16”) pile sizes. Piles were delivered to site in one piece with lengths up to 33.5 m (110 ft).INTRODUCTIONExcavations in cramped city centers and in between of existing buildings and other structures are facing more and more challenges. Installation of sheet pile walls is often problematic or even impossible due to obstacles in ground from old structures and due to demand to extend the excavations to even deeper and harder soil layers. Also installations of secant pile walls are facing difficulties due to cramped construction sites and constantly tightening execution times.On the other hand, an efficient and reliable piling technique suitable for the demanding soil conditions described above, percussion drilling, has been developed since the 1960’s, and especially from the mid- 1990’s, when the concentric drilling method with the ring bit and pilot was introduced. A new retaining wall application, the RD pile wall, was developed by combining that drilling method with the widely used retaining wall solution based on steel pipe piles and welded interlocks (a pipe pile wall normally installed with vibratory or impact hammers).PRINCIPLE AND MAIN BENEFITS OF THE METHODRD pile walls can be used in all soil conditions. Most beneficial the system is in extremely demanding soil conditions where the installation of traditional retaining walls is challenging or even impossible. The RD pile wall is a combination of drilled steel pipe piles and interlocking sections as shown in Fig. 1.Individual RD piles are connected to each other with interlocks welded to the piles on the automated welding line at the workshop. The matching dimensions of the drilling system and interlocking sections allow the installation of RD piles through stones and boulders and even into the bedrock, if necessary, in a single operation. Installation is done by a down-the-hole (DTH) hammer using the centric drilling system and oversized ring bits or a drilling system consisting of a pilot bit and reamer wings shown in Fig. 2."

Jan 1, 2017

By Peter Cali, David Yang, Rakshya Shrestha, Ralph Griffin, Sushil Kafle, Motoji Watanabe

"As a part of the ‘US Army Corps of Engineers - New Orleans to Venice, Louisiana Hurricane Protection Project’, deep mixing ground improvement was designed to reinforce the soft ground for the emergency repair of a 7297-foot (2,224 m) long section of the Mississippi River West Bank levee in Buras Levee District under the contract ‘Emergency Levee Repairs – Contract P-17A, Plaquemines Parish, Louisiana’. The ground improvement utilizes a series of soil-cement panels oriented in the transverse direction of the levee. Each soil-cement panel consists of overlapped columns installed by the deep mixing method (DMM). DMM is performed from the existing top of levee and extended to competent stratum at depths varying from 26 feet (7.9 m) to 47 feet (14.3 m) below the working platform. The main purpose of the DMM panels is to provide shear resistance to the levee against lateral loads at high flood water condition. The DMM panels support the additional vertical load created by the increased height of the levee for hurricane protection and control the long-term settlement of the remediated levee, which might otherwise occur due to the compression of soft foundation soils. The total amount of DMM treatment is approximately 54,000 cubic yards (41,500 cubic meters). This paper reviews the project background, subsurface soil conditions and presents the design, construction and quality control of the deep mixing work for this levee repair project.INTRODUCTIONIn August 2005, Hurricane Katrina caused major damage to the federal and non-federal flood control projects in southeast Louisiana. In September 2005, Hurricane Rita caused further damage to this flood protection system. In an effort to minimize further damage and to enhance the protection level, certain non-federal levees located on the west bank of the Mississippi river in Plaquemines Parish, Louisiana were incorporated into the New Orleans to Venice Hurricane Protection project by the US Army Corps of Engineers (USACE). DMM techniques were then utilized by the USACE in several of these emergency projects and in many medium sized projects between 2006 and 2010 (Bruce et al. 2012). This project (called P-17A hereafter) which forms a part of this protection system is executed under the contract Emergency Levee Repairs, Contract P-17A. This is one of the largest projects of the USACE after LPV- 111. The huge LPV-111 project (5.5 miles (8.9 km) of levee) treated by DMM), the largest DMM project ever conducted outside Japan, began in 2010 and was completed in 2012 (Cali et al. 2012, Bruce et al. 2012).DMM is utilized at P-17A to construct a series of soil-cement panels oriented in the transverse direction of the existing levee to provide shear resistance to the levee against the lateral load during high flood water condition. The project extends 7297-foot (2,224 m) along the West Bank Levee of the Mississippi River in the Buras district of Louisiana, parallel to Louisiana Highway 23 (LA-23) as shown in Figure 1. It is located approximately 60 miles (96 km) south-east of downtown New Orleans."

Jan 1, 2015

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 M. Reza Saberi, T. Ted Miyake

Driven piles are a common tool in any engineer’s toolbox for supporting large structures over very soft ground, especially in high seismic risk zones. Challenges include achieving sufficient vertical and lateral load capacities within the constraints of pile spacing and geologic conditions. This was the case for a project in Orange County, California with a state-of-the-art, $180 million plant for biosolids processing, biogas management and energy recovery located in marshland next to an existing waste water treatment plant. The new construction for the Irvine Ranch Water District included a 70-foot (21 m) tall building and three closely spaced, 90-foot (27 m) high, 65-foot (20 m) diameter, egg-shaped steel digester tanks. The lower 35-feet (11 m) of the tanks were constructed below ground level. The site was underlain by up to 45 feet (14 m) of highly compressible peat and organic clays with standard penetration test (SPT) blows as low as 2 blows/ft (30 cm). Some of the peat layers had measured in-situ dry densities of less than 30 pcf (480 kg/m3) with moisture contents of over 250 percent. The soft clays and peat were underlain by a dense layer of sand and gravel at depth. Groundwater was very shallow. While nearby sites were designated by others as seismic site class “D”, this site was clearly class “F” (SF) which required site specific seismic hazard and time history analyses. Six recorded time histories were selected from the 1994 Northridge, 1989 Loma Prieta (California) and 1999 Chi Chi (Taiwan) earthquakes for the ground motion analysis considering the magnitude of the earthquake, distance to the source, characteristics of the earthquake source (i.e. type of fault displacement), peak ground acceleration, local site geology, station type (i.e. free-field or small structure stations), and spectral content that was similar to the period range of interest. Following ASCE’s Guideline Document 7-05, a site-specific horizontal acceleration response spectra (ARS) was developed for the maximum credible earthquake (MCE) associated with the site.

Jan 1, 2018

By Randy R. Williams, Roberto R. Olivera, Brian W. Wilson, Marina S. W. Li

"An extensive, deep mixing (DM) ground improvement program using the Cutter Soil Mixing (CSM) technique was designed and constructed in 2013 to support up to 20 m (66 ft) high Mechanically Stabilized Earth (MSE) walls and bulk earthworks for the development of the Kitimat Liquefied Natural Gas (LNG) facility at Bish Cove, British Columbia. The deep mixing program consisted of overlapping rectangular panels of in situ cement treated soils, constructed using the CSM technique, to form barrettes covering an area of approximately 12,900 m2 (15,428 yd2) and providing suitable static and seismic stability of foundation soils for support of the proposed MSE walls, which would in turn support LNG facilities. The deep mixing program comprised of 1645 CSM panels that were constructed through varying thicknesses and discontinuous layers of very soft fine-grained marine deposits and/or loose sandy silt to silty sand deposits, embedding typically 2 m ( 6.6 ft) into dense silty sand to sand and gravel. CSM panel depths ranged from 5 m (16 ft) to 30 m (98 ft) and were constructed by treating approximately 73,900 m3 (96,658 yd3) of soil yielding average unconfined compressive strengths exceeding 2.5MPa (363 psi).This paper outlines the approach adopted for the design of the CSM ground improvement program in the highly variable subsurface conditions present at the site. A phased sitespecific investigation consisting of boreholes, test pits, Cone Penetration Tests, piston tube sampling, advanced laboratory testing and groundwater monitoring was implemented. In addition, soil-cement bench scale testing was completed, followed by installation of 8 CSM panels for field trial purposes. Extensive geotechnical static and seismic analyses including Limit Equilibrium stability analyses, liquefaction assessments, and advanced numerical modeling were undertaken to optimize the design and meet the project-specific design performance criteria. The Design-Build team worked closely to develop and implement Quality Assurance and Quality Control plans and managed significant construction challenges while achieving suitable panel termination depths."

Jan 1, 2017