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By Inc. Pile Dynamics, Daniel S. Belardo, Marcus Galvan, George Piscsalko

Soil nails are often utilized as a temporary or permanent earth retention technique for slope stabilization and for excavation retention for existing or new structures. Soils nails are generally advantageous as installation is relatively rapid and they can be installed beneath existing structures and where site access for equipment is limited. Due to the typically small cross-section of these elements, the inability to inspect the holes prior to grouting/concreting, and the various installation techniques utilized, quality control for assessing the integrity along the entire length is limited. Currently, quality assurance is conducted by load testing to verify the pull out capacity after installation. The load testing is typically done on a small percentage of the total number of soil nails. This paper will provide the results of a demonstration where the new Non-Destructive Test (NDT) method Thermal Integrity Profiling (TIP) was used to access the integrity of several soil nails along their entire lengths. This TIP method has been successfully used for several years to assess the integrity in drilled shafts and ACIP piles. The TIP method assesses the integrity across the entire cross-section and can identify regions where bulges, necks, and insufficient grout/concrete are present. TIP testing can also help assure that the contractor's installation methods are adequate and consistent for the intended design. For the project presented, instrumented Thermal Wire were affixed to the centered tension bars prior to placement in the excavated shafts. Temperature measurements were recorded from the hydration energy generated after grout/concrete placement, capturing the entire heating cycle. Manufactured defects were installed on the center bar at multiple locations. The results and conclusion will be discussed as well as recommendations for future use.

Jan 1, 2017

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

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

Jan 1, 2015

By Russell J. Denny

"A 25m deep cut-off wall is required for environmental remediation of a Former Chlor-Alkali Plant. Extensive trials were conducted to verify the effectiveness of the mixes proposed, with the requirements of the cut-off wall to include limiting criteria for hydraulic permeability, vapour permeability and strength, over a 100 year design life. A limited number of field CSM trial panels were installed on a nearby site with similar stratigraphy, and a variety of mixes and mixing methodologies were used, together with the extraction of deep wet grabbed samples from the panels, which were tested for strength, hydraulic permeability and gas permeability. Test results obtained from these trials revealed a trend which allowed the construction methodology to be decided. Further to this, the mix design needed to be resolved, together with sensitivity analysis on the variations in the mix which might occur during construction, as a result of normal unavoidable variations in construction technique. Laboratory sampling would be used at lesser expense, to resolve the final mix design and analyse the sensitivity of the possible mix variations. An initial series of laboratory mixed samples were prepared using soil samples and groundwater obtained from the site, and testing carried out. However the test results in this initial series of laboratory tests could not match the results which had been achieved in the field trials. Closer scrutiny and investigation and rounds of sampling and testing, then revealed laboratory techniques for mixing and sampling which provided a logical way to match the actual field test results. CSM Construction is due to commence soon and will provide more extensive results which can be compared back to the laboratory trials. This project provides a valuable opportunity to resolve methods of laboratory sampling so that they compare well with results from in-situ deep mixing.INTRODUCTIONThe former chlor-alkali plant at Botany, NSW, which operated from 1945 until 2002, used mercury cell technology and brine solution to manufacture chlorine, caustic soda, hydrochloric acid, sodium hypochlorite and ferric chloride. Mercury contamination is present in the permeable alluvial soil profile beneath the site. The mercury is present in the form of elemental and inorganic mercury, together with dissolved methyl mercury in the groundwater and soil profile beneath the site and also down-gradient of the site, to depths of up to 25m. Residual clay and sandstone bedrock at approximately 25m depth are relatively impermeable and limit the contamination plume. A cap and contain approach has been recommended by consultants Golder Associates, and this involved a subsurface containment wall, or cutoff wall, to restrict groundwater ingress and egress, and lateral subsurface vapour migration. The cut-off wall is situated on the perimeter of the site, with a total length of 430m and passing through alluvial Botany Sands, with a nominal key into the underlying residual clay or sand stone at 20 to 25m depth. An HDPE liner insert was proposed for the upper 7m of wall above the water table, to further limit gas permeability."

Jan 1, 2015

By Robert Thurner, Albin Norrman, Sami U. Raja

The West Link is a double track railway project currently under construction in Gothenburg, Sweden. The project includes the construction of 8 kms of track, 6 kms of which will be in tunnels. Beside several large excavations, three new stations will be built: Centralen, Haga and Korsvägen, all within the city of Gothenburg. The first construction phase of the project began in May 2018, and the finalization of the project is expected in 2026. The project is divided into five sections. Keller is involved in four of these contracts since the design & planning phase in 2018 assisting the special foundation works with various geotechnical techniques including Dry deep soil mixing (DDSM), jet grouting, rock grouting, uplift piles, sheet piling and rock dowels. The core idea behind successful collaboration has been to apply the right product for a location specific challenge which can help optimise costs & time for the project with a minimal environmental impact. Due to the extensive nature of the project, a team of experts from various locations around the world is helping design and execute various foundation technologies and providing solutions to the practical challenges in the project like working close to existing structures, rail lines, river etc.

May 1, 2022

By Vivian M. Troughton, Clifford J. Wren, Tony P. Suckling

"Secant pile walls are used for the construction of deep basement walls and earth retaining structures. Risk associated with secant pile walls is commonly perceived as being the safety of site personnel and the public during piling operations, or safety used in design. It is recognized that both of these are of paramount importance, but additional risks associated with the construction methods must also be considered to complete the risk management profile for any project. For the particular case of secant pile walls, if Clients take a ""back seat"" they may be unaware of the total risk package they are procuring. The authors argue that the piling contractor should be involved at the earliest stage giving input into the overall risk management process. Such early involvement within the professional team will maximise cost benefits to the Client and minimise the delays and cost increases sometimes associated with these works. A consistent methodology for identifying and then managing all the risks associated with secant pile walls is proposed. An example is used to demonstrate how this methodology should be employed. INTRODUCTIONThis paper discusses the value of a complete and integrated risk management process for structures with basements formed using a secant pile wall.The risk associated with any secant pile wall can be consicfered as comprising four components;1. Safety of people on site2. Safety of design or design methodology3. Construction risks4. Commercial risksAny risk management system needs to fully consider and integrate each of these four components to maximise the likelihood of a successful outcome for the basement.This paper concentrates on the construction risks for secant pile walls, as these are not often understood by the Client (in this paper the term ""Client"" also includes the main contractor, principal contractor, Engineer, Planning Supervisor, quantity surveyor and cost consultant)."

Jan 1, 2005

By Jakub Szary

Excavation and shoring adjacent to the above-grade Gilmore train station and elevated guideway was undertaken in 2019. A perimeter secant pile cut-off wall was constructed to a depth 37 m (121 ft) below ground surface consisting of 1.0 m (3.3 ft) diameter drilled piles spaced 750 mm (2.5 ft) on-center, tied back with soil anchors, and reinforced with W610 steel sections every 4th pile. A bracing/jacking system was also constructed to support 3 free-standing guideway caissons within the excavation. An automated instrumentation program was installed to monitor movements of shoring walls and train infrastructure in real time and consisted of a robotic total station, inclinometers, tiltmeters, strain gauges, extensometers, and anchor load cells. Baseline monitoring was able to establish diurnal and seasonal movements within the structure, strongly correlated with temperature. The system actively monitored various shoring elements and train infrastructure in real time and alerted the project team when values exceeded predetermined threshold values. Remote reconfiguration of the automated system allowed for more frequent monitoring during jacking of Pier 29 in March 2022. Monitoring data was in agreeance with on-site manual surveying results and jacking dial gauges, and proved to be a reliable monitoring system for construction applications.

Sep 1, 2022

By Eric S. Lindquist

Two microtunnel access shafts were constructed using the Cutter Soil Mixing (CSM) method in the San Joaquin Delta region of California, east of San Francisco. Unlike conventional slurry walls and diaphragm walls that utilize concrete, soil mixing relies on blending the soils in situ with a cement slurry to create a soil-cement wall. Cutter Soil Mixing technology utilizes two sets of vertically mounted cutting wheels rotating about a horizontal axis to produce rectangular panels of treated soil. Overlapping of the soil mixed panels enabled the construction of two circular shafts. CSM panels were constructed to a depth of 29 m (95 ft) for the microtunnel jacking shaft and to a depth of 19 m (63 ft) for the microtunnel receiving shaft. The site presented several challenges, including the high depth of treatment, the variable nature of the alluvial soils, and the high water table. This paper describes the CSM technique and presents the design, construction, quality control measures and advantages of using this method for this project.

Jan 1, 2010

By Hidekatsu Takeuchi, Masaru Sakakibara, Shigeo Tanabe, Kenji Harada, Akihiko Suzuki, Shoji Morihana

"Deep mixing (DM) method, one of the most commonly used solidification methods, is based on the principle of solidifying soft ground. It can be classified into two categories such as Cement Deep Mixing (CDM) method and Dry Jet Mixing (DJM) method which apply hardening agent in slurry condition and in powdery condition respectively. In recent years, DM methods have undergone changes that have evolved them from the traditional method to meet the needs of the diversifying market. Among them, the Contrivance-Innovation Clay Mixing Consolidation (CI-CMC) method is a DM method which mixes a cement-type hardening agent in slurry condition mechanically with soils in situ and incorporates the innovative technique, “atomized ejection” that has been developed to allow faster installation of larger diameter columns without sacrificing quality compared with conventional methods. At this technique, the atomized hardening agent is discharged together with compressed air through a device incorporated into the mixing blade. It also has advantages of performing the works with low-displacement of the surrounding soils in consideration of environmental friendliness and with higher penetration capability against hard ground.This paper presents the technological outline of the above-mentioned CI-CMC method, focusing on the atomized-ejection technique, followed by some construction examples, applied to the self-earth-retaining wall, to the hard ground and the area adjacent to the existing structures.INTRODUCTIONAccording to the accumulation of its case histories, Deep Mixing method has been receiving the demands of its application to more challenging conditions, such as harder ground condition, and requirement of lower displacement of the surrounding ground during its operation. In addition, to match its price against the other cheaper methods and widely receive its benefit of higher quality, the cost reduction of Deep Mixing is also one of the major challenges. For the cost reduction, higher productivity and lower consumption of the material to obtain the equivalent strength and homogeneity with the conventional method are required.The Contrivance-Innovation Clay Mixing Consolidation (CI-CMC) method has been developed to meet these demands. CI-CMC incorporates the mist ejection that has been developed to achieve faster installation of larger diameter columns without sacrificing quality compared with the existing methods. Normally, we obtain cement columns of about 1.0 m in diameter by using Deep Mixing method. To increase the productivity, it is not preferable to drastically increase the penetration and withdrawal speed of the mixing blades because of the hardness of the ground and restriction by minimum number of passage of rotating blades per a certain height of the soil cement. Instead, the expansion of diameter of the columns will simply increase the productivity. The development of the new mist ejection system, as shown in Photo 1, has enabled the diameter of soil cement columns to 2.0 m on single axis while 1.6 m on double axes. Mist ejection means that the hardening agent slurry is sprayed into the ground in mist form together with compressed air thereby achieving homogeneous mixing and reducing the resistance on rotating blades."

Jan 1, 2015

By Chu E. Ho, Paul Napoli

This paper presents the performance of nineteen open-ended steel pipe piles driven through highly variable overburden soils into glacial till and schist bedrock. The piles were 16 inches in diameter and 0.656 inches thick, with yield strength of 50 ksi. The piles were designed for a service capacity of 250 kips and were driven to achieve an ultimate geotechnical capacity of at least 500 kips. Due to the large variation in the ground conditions, installed pile lengths ranged from 25 to 66 feet. Some piles were driven to refusal on the bedrock while others were terminated at final driving resistance of 2 to 7 blows/in. Two piles were suspected to be plugged during driving while others did not. Each pile was instrumented with strain gages and accelerometers near the pile top, and observed using a Pile Driving Analyzer (PDA) to provide preliminary guidance on pile capacity achieved at end of initial drive (EOID). The influence of plugged and unplugged pile toe conditions on the interpretation of pile capacity was investigated using Case Pile Wave Analysis Program (CAPWAP). Characteristics of driving energy, compressive and tensile stresses developed in the steel pipe piles, and the resulting pile deformation behavior are discussed. INTRODUCTION The Hunters Point South redevelopment in Long Island City, Queens is one of New York City’s major efforts to transform former manufacturing zones into mixed developments for the middle-income community. The site is located along the eastern shoreline of the East River and Newtown Creek. The development included low to high-rise residential buildings, a public school and retail structures. Open spaces were created along the East River and Newtown Creek waterfronts in the form of a continuous park providing for recreational and community related activities. Waterfront structures included small park buildings, walkways and viewing platforms with the shoreline protected by revetments as part of the City’s flood mitigation strategy. The project was implemented in two phases, with completion of construction for Phase 1 in 2013 and Phase 2 in 2019. Based on available historical information, extensive reclamation took place between 1855 and 1898. After 1951, changes to the shoreline were made along the East River, including the removal of reclaimed land along the northern portion of the project site to allow for docking facilities. By 1977, these facilities had been demolished and backfilled to form the current shoreline configuration. The present site was temporarily used as a parking lot with stockpiles of fill mixed with construction demolition rubble, rip-rap and boulders of varying heights across the site. The existing ground surface varied significantly up to approximately 25 feet difference in elevation. The stockpiles were removed and the site was re-graded during final development of the project. This paper discusses the foundation design challenges due to the loose overburden soils and potential obstructions within the fill material, in particular, the issues relating to installation of open-ended steel pipe piles through the ground conditions encountered on site.

Jan 1, 2019

By John S. Pack

The application of square shaft helical piers in expansive soils is a standard of practice in many areas of the United States. Over 20 years of performance monitoring show exceptional performance and economy will result if proper design procedures, specification requirements and installation procedures are followed. This is true for new foundations and the repair of existing foundations, including lightly loaded wood-frame structures on expansive soils. Proper design includes: 1) site geotechnical characterization, 2) pier layout such that each pier is loaded to its maximum design capacity, 3) maximize spans between piers, 4) minimize the number of piers, 5) isolate the structure from the expansive soil with an appropriate void zone below all grade beams, slabs or other components that would otherwise be in soil contact and 6) utilize only single helix piers. Proper specification employs a performance specification that specifies: 1) the design load on each pier with a suitable safety factor, 2) the minimum installation torque, typically 4,000 ft-lbs (5.4 kN-m), or refusal, 3) a minimum pier shaft steel Fy = 70 to 90 ksi (483 to 621 Mpa) and pier helix steel Fy = 80 ksi (552 Mpa), 4) 1.5 to 1.75 inch (38.1 to 44.5 mm) square shafts, 5) smooth shaft surface, 6) the ICC Evaluation Report (ER) number of the manufacturer and 7) the manufacturer ISO 9001 certification for material quality control. Proper installation requires: 1) equipment with sufficient axial compression force (crowd) on the pier shaft so the helix engages the soil and advances to the specified minimum installation torque or refusal, 2) additional specialized techniques for expansive soils and 3) qualified specialty helical pier installation contractors experienced in expansive soils who submit and utilize pier configurations, techniques and equipment that will most effectively and economically meet the specified performance.

Jan 1, 2007

By Vijaya Bhushan Rao, Jason Redgers

A substantial lifestyle destination in the United Arab Emirates, in the Emirate of Abu Dhabi comprising of 1315 villas, town houses and non-residential leisure facilities is built over an area of 280 hectares of former mangrove areas, natural sands and reclaimed lands. Large-scale subsoil investigations including field and laboratory testing carried out dividing the entire site in to 7 clusters. This investigation revealed alternating layers of loose sands and silty clays within the load influence zone of planned foundations, showing susceptibility to excessive settlements. Therefore, ground improvement works were undertaken using a combination of stone columns, Rapid Impact Compaction (RIC) and excavation and replacement of soils plus a 0.4m thick load transfer platform. This was necessary to limit the settlements, increase-bearing capacity and prevent long-term settlements. 30 no’s of full-scale Zone Load Tests, ZLT were carried out each for a duration of 30 days in order to ascertain the anticipated long-term settlements in the clay layers. In addition, further testing of electrical cone penetration tests, CPT, and Plate Load Tests, PLT. The use of Priebe and Asaoka’s observational procedure were applied to predict the final settlements and the use of back-analysis from the 30 days Zone Load Tests, ZLT results to establish the site-specific consolidation parameters in clay layers to optimize the design and ground improvement works.

Sep 8, 2021

By Maral Papazian Bedian

"Case 2. 100th Street Bus Depot: Elimination of Deep Caissons in Favor of Spread FootingsThe PROJECTThe 100th Street Bus Depot is a new five-story bus terminal for the New York City Metropolitan Transit Authority occupying one city block in Manhattan between 99th and 100th Streets, and between Lexington and Park Avenues. It replaces a former two-story garage, built in the 1890’s and initially used as a trolley-car barn. The new structure is a steelframed building with concrete floors and includes a partial basement near its middle. The easternmost column line with design loads of 10 MN (1,125 tons) is within 1.5 m of the underlying multi-tube Lexington Avenue subway system. To support the new columns along the subway line, the project bid plans had called for 1 m diameter and 17 m deep drilled shafts. The upper 14 m of each unit would have required 50 mm separation from the surrounding rock to prevent stress from being imposed on the roof and walls of the adjacent tunnel. The column loads were thus transferred to below the base of the tunnel and supported by 3 m long sockets in bedrock. The bid documents contained extensive test boring information, which revealed that the project site was underlain by massive Manhattan Mica Schist bedrock within just 3 m below street level. In fact, the Lexington Avenue two-level and multi-tube subway had been tunneled through this rock circa 1910, leaving an about 6 m thick solid roof over the upper-level subway. The NX rock core recovery values were near 100 %, with average RQD of 75 %.The CHANGEThe Bus Depot project was let as a design/build contract with a very aggressive fast-track schedule. Both the pre-bid preliminary design and the subsequent final design by the Contractor’s own hired design engineers relied heavily on very restrictive codes, including unnecessarily conservative approaches to seismic design. Any suggestion for value engineering change was undesirable and was strongly resisted. Yet, objecting against the blind reliance on codes in foundation design, the author questioned the real need for the deep drilled shafts to support the columns along the subway. The unsupported statement that no stresses from the new structure can be imposed on the roof and walls of the adjacent tunnel was not sufficient reason for the drilled-shaft design. Unconvinced that deep shafts were necessary, the author rushed to MTA’s warehouse where many rows of rock core boxes were neatly stacked. Careful inspection and some simple testing of the rock cores with the blows of a geologic hammer gave support to the reservations about the design. Later, as expected, the schist bedrock at this site was found to be hard to very hard with unconfined compressive strength values estimated to range from at least 70 MPa to over 100 MPa (10,000 psi to 15,000 psi). The tensile strength of the rock was assessed to be minimum 5 MPa (750 psi)."

Jan 1, 2003

By Fredrik Sarvell, Harald. Ihler, Veli-Matti Uotinen, Jukka Rantala

"Many of the valid international building codes state that the lateral support provided by the soil is sufficient to prevent buckling of fully embedded piles. However, the development of small diameter micropiles and especially the use of high strength steel have evolved to applications including high capacity elements. The ultimate structural load bearing capacity of a pile in a cohesive soil is decided by examining which gives the lowest value, the peak buckling load and the resisting moment provided by the surrounding soil medium or the structural capacity of the pile cross section. In both cases, the initial deflection of the pile is a significant factor when the axial load bearing capacity of the pile is determined. Steel micropiles are joined commonly with mechanical splices. A less rigid mechanical splice is often a weaker hinge that allows the pile to bend and deflect more during installation increasing the initial deflection of a pile. In addition the less rigid splice element decreases the bending capacity of a jointed pile section and the ultimate axial load capacity of the entire pile. A series of FE analysis performed for various pile sizes suggest that the steel pipe piles including separate pile sections and mechanical splicing elements should have the combined bending stiffness of EIshaft = 0,75 × EIpile. This requirement yields to the buckling resistance of at least 96 % of the solid reference pile with the sameinitial eccentricity in similar soil conditions.IntroductionMany of the valid international building codes state that the lateral support provided by the soil is sufficient to prevent buckling of fully embedded piles. However, the development of small diameter micropiles and especially the use of high strength steel have evolved to applications including high capacity elements. The potential buckling of these very slender high capacity piles in soft soils may in many cases be the controlling design factor of the pile, especially with end bearing micropiles.A typical sequence of soil strata in Nordic countries, such as Norway, Finland and Sweden, constitutes of friction soil or dry crust clay on top of soft clay followed by till. This soil stratum often rests on solid bedrock of granite or gneiss. Conditions like these are suitable for slender end bearing piles subjected to buckling and especially steel pipe piles where most of the material is located at the edge of the cross section. Other reasons for using slender steel pipe piles are for example fast installation with minimal waste, efficient manufacturing and relatively well established design and execution procedures. Minimum quality criteria’s regarding splices for steel pipe piles are recommended to be set as national provisions to ensure quality and comparable procurements in foundation business."

Jan 1, 2014

By Jeongbok Seo

The Dulles Corridor Metrorail Project (DCMP) involves the design and construction of a 23.1-mile extension of the Washington Metropolitan Area Transit Authority (WMATA) rail system. The initial 11.7-mile extension, with five transit stations and a new service and inspection yard, is to be constructed. The construction plan for the initial 11.7-mile extension includes installation of a total of an estimated 4,250 or 160,000 linear feet of driven 12x53 steel H-Piles at more than 80 different locations. At the time of this paper, approximately 40 percent of the piles have been installed and the remainder of piles will be installed by the end of 2010. This paper describes: 1) subsurface investigation program, 2) application of existing Codes and impact on the design of H-Pile, 3) design methods to determine geotechnical bearing capacity and pile tip elevation, 4) verification of capacity including PDA and Static Load Tests, 5) project specific pile load tests, and 6) QA/QC during pile driving.

Jan 1, 2010

By Pirooz Barar

The new Stanley Hall building will house the center for bio-engineering and technology research for the UC Berkeley campus. The structure is located at the northeast part of campus, adjacent to Donner Lab, on the west side of Galey Road, approximately 600 ft. from the Hayward Fault. The building site has a complex geological formation. To the east there are clayey soil shale formations, and to the west there is greywake shattered sandstone. The water table is at 10 ft. below grade. The structure will consist of 6 levels below grade and 8 levels above grade, which calls for an 83 ft. deep excavation on the northeast side. There is an approximately 35 ft. grade differential between the east and west sides of the building. Because of this severe grade differential, as well as high water tables, the lateral forces on the building due to uneven earth pressures would have been 2 times the magnitude of the seismic forces. To mitigate the lateral earth pressures, a permanent Soil Nailed Wall, integrated with the structural system of the building was designed. PB&A, Inc.?s in-house design program ?Winslope? was utilized to design the system and the data obtained from a rigorous monitoring program, were used to calibrate several computer runs using Plaxis program.

Jan 1, 2004

By Alexander Scheuermann, Martin D. Larisch, David J. Williams

"Drilled displacement piles (DDP) have been used around the world for decades as foundation elements for structures and embankments. Typically the pile toes are designed to penetrate into stiff or dense soil formations to achieve sufficient base resistance. Recent research at The University of Queensland in Brisbane, Australia has discovered that the in situ stress conditions in stiff to hard clays is directly related to pile installation rates, which in turn are a function of the piling rig capacity and ground conditions. With adequate and constant pile penetration rates in situ stress conditions in the stiff to hard clay are increased by about 40%, resulting in significantly higher pile capacities. If pile penetration rates are too slow the in situ stress conditions are reduced considerably by remoulding and shearing of the clay, potentially causing reduced pile capacities. The paper presents the results of full-scale test piles at a stiff to hard clay site installed using different full-scale piling equipment.INTRODUCTIONDrilled displacement piling (DDP) is a piling technique in which a hollow stem, fitted with a purpose built displacement tool at the bottom, is drilled into the ground. Dissimilar to non-displacement piles, like Continuous Flight Auger (CFA) piles or conventional rotary bored piles drilled with kelly bars, the soil is not excavated during the DDP penetration process, but is displaced laterally and to a lesser extent vertically. The cavity created by the drilling tool is filled with highly workable concrete during the extraction process. The DDP technique is very economical providing high production rates and creating only marginal drill spoil, which has led to its increased global usage during the last decade. The typical DDP installation process is described in Figure 1."

Jan 1, 1900

By Daniel Stevenson, Richard Guenther

"The preservation of historic buildings is not only essential to the understanding of our national heritage, but it is also environmentally responsible to adapt existing buildings to compatible new uses. With this perspective, the American Enterprise Institute began exploring options to expand the newly acquired Andrew Mellon Building, located at 1785 Massachusetts Ave. NW in Washington, D.C., without causing any harm to the Beaux Arts style limestone façade and its plaster interiors. The building is a National Historical Landmark, but its 72,000 sq ft (6,690 sq m) of usable floor space did not meet the needs of its new owner. The building perimeter is very near the property line, so horizontal expansion was not possible. Adding height to the building was not an option, as this would have altered the historic nature of the building exterior. The only feasible option that could provide the desired floor space was to add a new floor underneath the existing structure. By adding a level beneath the existing building, an additional 28,000 sq ft (2,601 sq m) of floor space could be produced.Berkel & Company Contractors was chosen as the deep foundation/shoring contractor tasked with ensuring that the existing structure was stable and remained undamaged during the excavation and construction of the new lower level. To accomplish this, Berkel provided a shoring system that would act as both excavation support and permanent deep foundation elements for the final structure.Preservation of the existing limestone façade and plaster interiors was critical to the success of the project, as additional foundation settlements could damage these irreplaceable building components. Project specifications, therefore, included very stringent limits for foundation settlements. The maximum allowable total settlement for all existing building walls and columns was ¼ in (6 mm) for the duration of the project."

Jan 1, 2017

"The Morris Island Lighthouse (MIL) is located between the jetties leading to the Charleston Harbor and Folly Beach, S.C. The present structure is the third lighthouse to occupy this location. The first navigational aid was erected in 1673, and consisted of a raised pan filled with pitch, which was set afire at night to guide early ships. The next structure was built in 1767, and constituted the first real lighthouse, standing 42 ft (12.8 m) in height. In 1838, a second lighthouse was built on the site, and it measured 102 ft (31 m) in height and featured a revolving light. This structure lasted until 1862 when Confederate troops, during the Civil War, destroyed it to deny its use to Union troops.Navigators steered these waters without a lighthouse for nearly a decade until 1876, when the current structure was built under the direction of the U.S. Army Corps of Engineers (USACE). In 1886, the Charleston area suffered a M7.6 earthquake. Significant damage was caused throughout much of the area, including a slight “list” of the lighthouse to the northeast. As a result, the cast of the beacon was reduced from 18 mi (29 km) to about 6 mi (9.7 km), causing much distress to navigators until the beacon platform was releveled and remains at this list to the present day.Conditions for ConcernThe current lighthouse was originally constructed about 1,200 ft (366 m) from the shoreline. Over the years, USACE has undertaken several programs to meet the increased shipping and navigation demands in the Charleston Harbor. Around the turn of the last century, two jetties were constructed, which drastically changed the approach direction for ships entering the harbor. In subsequent years, the harbor began to experience accelerated siltation."

Jan 1, 2017

By Yahia M. Al-Smadi

Effect of lateral loading against existing sheet pile wall and distribution of gravity loading due to various number of construction loading scenarios were studied. The objective of this effort was to determine the loading case that permits the contractor to utilize a 400 ton crane at the specified location with the existing limitation imposed on site. Staged analysis was determined as the methodology that will more accurately predict the exiting and additional stress due to the impose crane loading. A reliable and robust analysis (ANSYS) software was used to complete both 2D and 3D finite element model and analysis. Analysis model parameters such as material properties, non-linear behavior of the soil, and meshing are presented and discussed. At the conclusion specific range of crane operation and pick weights operating on existing concrete mat supported on top of an existing tunnel was reviewed and deemed acceptable.

Jan 1, 2010

By David Guy, John Stanbury, Gilbert Tallard

"In 2009, storm surge from Hurricane Sandy inundated the Bay Park Sewage Treatment Plant located at El. +4 to +12 (+1.2 to +3.6 m) in East Rockaway, Long Island, NY. With all systems down, raw sewage water mixed in the floodwaters. A recurrence of such an event being unacceptable, and in view of rising future sea levels, a flood protection project was developed by Nassau County with funding coming in large part from the federally funded Sandy Rescue Fund. Designed by Arcadis/Hazen & Sawyer Engineers J.V., the protection took the form of a perimeter barrier capable of withstanding future storm surge. Due to limitations imposed by property lines and existing facilities, a levee design with three different types of cross section was developed to adapt to each location, adding construction complexity. The Long Island subsurface is characterized by beach sand extending to great depth. The clay required for the core and levee cover therefore had to be brought in from out of state. A thin silty clay layer at El. -23 to -25 (-7.0 to -7.6 m) served as an aquitard. The under-seepage was reduced by a hanging cut-off wall designed as a vibrated beam thin wall and filled with a salt water resistant, low permeability, self-hardening slurry.INTRODUCTIONOn October 29, 2009, Hurricane Sandy hit New York City, with a devastating effect on the region. The low lying Bay Park Sewage Treatment Plant (STP) (Fig. 1) serving Nassau County on Long Island was submerged (Fig. 2). All basements and underground mechanical facilities were flooded (Fig. 3) and millions gallons of effluent were released into the waters of the nearby Hewlett Bay which connects via other small waterways to the Atlantic Ocean."

Jan 1, 2016