Search Documents

By James C. Scott

Compression and tension load testing were performed on bored concrete piles installed to depths of 18 to 34 meters below excavation levels for a large mixed-use development in Kuala Lumpur, Malaysia. The 900 mm diameter piles were installed in weathered graphitic schist bedrock. Load testing confirmed the side shear and end bearing capacities of the piles. The work formed part of the investigations for the 56,000 m2 site which includes a 79-story office tower, hotel tower, apartment tower, retail complex, and plaza area underlain by 4 to 6 basement levels. The paper provides the results of the site investigations, pile-load testing procedures, pile-load settlement behavior, and shaft load distribution.

Jan 1, 2007

By Alan G. MacKinnon

The current piling practices in the U. S. have, to a great degree, been influenced by our founding fathers. When our constitution was written by the delegates from the original thirteen colonies, it was a document of compromise. Generally, the individual states retained their sovereign power over those duties that they had historically performed. The concept of States Rights has been tested throughout our history and has been preserved as of today. An example of the extent of this protection is occurring in the State of Ohio where I currently live. Each of the 50 states receives funds for highway construction from the federal government, approximately in proportion to its population. Congress, when it allocates the funds, quite often attaches amendments to the funding bill to exercise their authority. The major amendment prior to the most recent increase in the speed limit to 65 mph from 55 mph was to increase the legal drinking age to 21 from 18 years old. Embodied within the bill was the provision that the Federal government deduct a percentage from the allocation of any state that did not revise its legal drinking age law from 18 to 21. In the State of Ohio, this change in the law was put to a vote of the people and it was defeated. The federal government now is deducting funds

Jan 1, 1987

By Peter Deming

"PART 2 OF 2 (CONTINUED FROM SUMMER 2006 EDITION) CONSTRUCTION ISSUES (cont’d) The Influence of Ground Conditions on Collapse Sand and gravel strata provide frictional resistance to support active earth pressure. The angle of internal friction has only slight influence on computed stability. Sand and gravel material design parameters can be defined with SPT N-values. Silt strata should be analyzed using internal friction. Definition of soil parameters should be performed by laboratory testing. Cohesive materials, especially soft clay and peat, require careful definition for design. Shear strength should be determined by laboratory testing. Work platforms constructed over granular strata improve the ground resistance by increasing confining pressure. However, temporarily increasing overburden stress on cohesive ground reduces trench stability. If the ground contains soft cohesive deposits which are not normally consolidated to the construction overburden, these must be stabilized before attempting trench construction. Use of wick drains and surcharge fill to improve the ground is recommended. Ground stabilization work requires time, and should be performed by the Owner prior to trench excavation. The addition of cement, stone columns, or other measures to support trench excavation equipment is typically determined to be more expensive and less dependable than ground improvement. Excavation through peat can be especially problematic. Peat materials rapidly compress when earth pressures exceed preconsolidation stresses. Backfill materials provide a horizontal stress on the trench wall which can exceed the bearing capacity of peat. As the peat compresses, the trench becomes wider, and slurry levels drop and trench stability can rapidly deteriorate. If the peat is the closure layer, a shallow key is recommended. If peat is present on the trench wall, preconsolidation with surcharge is recommended. Bottom preparation and Backfill Placement Trench wall stability is a temporary condition which must be controlled by proper design and construction of work platforms and slurry features which influence ground support. Backfill materials and intimate contact of the backfill with the closure layer are permanent conditions which are the end goal of the work. The most common reason slurry trenches fail to provide working barriers is improper bottom closure. Either the closure layer is not engaged, or the backfill is not in intimate contact with the closure layer. This can result from construction problems associated with sidewall collapse described above, slurry performance and/or degradation, backfill placement methods, and failure to maintain the trench bottom clear of sediment prior to placing backfill."

Jan 1, 2006

By Ting-Wei Wang, Yung-Wen Chen

Artificial ground freezing is commonly used globally during excavation of shield tunnels and for groundwater control. It is a special construction method for temporary ground improvement that involves introducing coolant into underground pipes to freeze water in the soil. The frozen soil is cemented together as a result to form a frozen wall, which provides high strength and low permeability. Once the thickness of the ice wall reaches design requirements, underground excavation can be conducted with the coolant removed afterward to return the soil to its original state. This technique is cost-effective in scenarios where complete groundwater cut-off and excavation support are required; where work is deep underground and faces difficult ground conditions and where access restrictions limit the use of other displacement-type ground improvement techniques. Due to the demand for shield tunnel construction for utilities in Taiwan, ground freezing has become an important soil stabilization method there. In this article, we will share two brine freezing case studies and an in situ liquid nitrogen experiment that was conducted to develop this technique.

Feb 1, 2022

By Vladimir M. Korolev

The field studies conducted at the experimental-production sites allowed to develop the technology of arranging drilling piles in loess subsiding grounds over 25 m deep and over 250 mm in diameter, to select optimal compositions of flush fluids, to assess the carrying capacity and field of use of the piles under test and to produce a special equipment. The dependence of the ultimate axial pressing-in load on pile driving into the non-subsiding section, its diameter and method of fulfillment, as well as the ground moisture dependence of the specific ground resistance along the piles' side surface within the limits of the subsiding section were determined. The study results allowed to reduce the length of the work piles and the number of bars in the reinforcement frames. The obtained experimental data enable to give a preliminary assessment of the piles' carrying capacity under complicated engineering-geological conditions of subsiding grounds.

Jan 1, 2002

By John S. McCartney

This paper focuses on the seasonal thermo-mechanical response of two energy foundations installed at the new Denver Housing Authority Senior Living Facility in Denver, Colorado. The two drilled shaft foundations, which have diameters of 36 inches and depths of 45 ft and are end bearing in the Denver shale formation, include a closed-loop series of polyethylene tubes through which fluid is circulated to exchange heat with the surrounding ground. The tubes within the foundations are coupled together with the conventional ground source heat pump system for the building and were installed to evaluate the heat exchange response of the foundations as well as any thermo-mechanical soil-structure interaction effects. A series of vibrating wire strain gages and thermistors were installed at different depths in the foundation to record the thermo-mechanical strain and temperature at different depths. Also, pipe-plug thermocouples are used to measure the inlet and outlet temperature of the heat exchanger fluid entering each of the foundations, which is necessary to evaluate the total heat exchange for the foundations and the efficiency of the heat pump. This paper will describe the energy foundation construction processes, the strain distribution and ambient temperature profiles during building construction and the seasonal strain and temperature distributions during heating and cooling of the building. The data indicates that typical heat exchange associated with heating and cooling operations leads to strains which are within acceptable limits, and that the foundations can provide a clear option for absorbing the base heating and cooling load for the building.

Caissons hand dug to a depth of about 100 feet were used to underpin three important structures at an industrial site in the State of Utah. The caisson shafts extended through 30 to 40 feet of coarse, granular soils and 25 to 60 feet of sands and clays to bear on a very dense, coarse gravel and cobble stratum near the water table. The shafts were belled to 12 feet square at their bearing elevation. Bearing pressures of 20 ksf were assigned. The shafts were lagged with timber. The use of hand-dug caissons allowed continuous operation of the facility during underpinning. Settlements after underpinning have been minor and well within the estimated magnitudes. Instrumentation was placed in two of the caissons with varying degrees of success.

Jan 1, 2010

By Filippo Leoni, Wesley Schmutzler

"The LPV-111 East Back Levee Improvement Project lies along the Gulf Intracoastal Waterway (GIWW) in Orleans Parish of New Orleans, La., and is an essential component of the New Orleans Hurricane Protection System. The Hurricane Protection Office of the U.S. Army Corps of Engineers (USACE) attributed failure of the New Orleans East levees system to overtopping, erosion and subsequent breaching of LPV-111 along the GIWW, as well as other sections of flood protection during Hurricane Katrina in 2005. The existing levee suffered extensive damages from Hurricane Katrina, such that the USACE elected to provide earth stabilization and to rebuild the levee sections. Due to the adverse geotechnical properties of the foundation soils, the Corps deemed ground improvement necessary to stabilize the new levee and to limit its footprint. Wet Deep Mixing Method (DMM) was selected as the most suitable technology for this task.ChallengesDesign: This reach specifically protects East New Orleans and the Bayou Savage National Wildlife Refuge, the largest urban wildlife refuge in the U.S. and home to several threatened or endangered species of birds as well as many reptiles, amphibians and small mammals. The Corps chose DMM due to the sensitivity of the protected marshlands and because the method limits the footprint of the raised levees. The increase in the load bearing capacity of the treated soil significantly decreases the footprint necessary to attain the required height increase. This limitation required the new levee to have steep slopes, drastically increasing the surcharge on foundation soils characterized by overall poor geotechnical properties (soft clays and peats). The design also considered the increased horizontal stresses on the levees due to the extreme storm surges during a hurricane.The design of the 1.6 m diameter (5.25 ft) DMM elements called for overlapping them to form a double auger element that formed buttresses perpendicular to the levee alignment. The contractor installed the buttresses at a maximum on center spacing of 4.7 m (15.5 ft). One additional double auger DMM element was midway between consecutive buttresses at the centerline of the levee to further help prevent settlement (Figure 1)."

Jan 1, 2013

By Alice Y. Tseng, Dan MacLean

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

Jan 1, 2017

By John C. Niedzielski

The PHX Sky Train is a five mile long automated people mover system located at Phoenix Sky Harbor International Airport. Phase I of the PHX Sky Train includes the design and construction of 227 drilled shafts supporting three stations and approximately 9,000 feet of elevated guideway. The guideway includes a 100 foot high, 330 foot long span extending over an active taxiway, which will be the first system of this kind over an active taxiway in the world. The soil conditions in this area generally consist of alluvial Sand, Gravel and Cobbles (locally known as SGC) deposited by the nearby Salt River. The foundation system will support relatively high axial loads, lateral loads and moments due to the height of the guideway above the ground surface, where it needs to pass over existing concourse walkways, bridges, a taxiway and buildings. Drilled shaft design involves designing 4.5-foot to 9-foot diameter drilled shafts within the SGC deposits, most of which extend well below the groundwater table. There is a high potential for collapse of drilled shaft excavation sidewalls within this material. Such extreme design loading conditions, together with difficult ground conditions at the site, result in several challenges for the design and construction of the deep foundation system for the guideway and stations. A load test shaft was designed and constructed as a means to provide site-specific measurement of axial performance under these difficult conditions. Results from the load test were used to reduce the size of the drilled shafts. This paper provides an overall description of the PHX Sky Train project, a summary of the ground conditions, design requirements, load test results and construction methods and equipment used to successfully install the drilled shafts for this project.

Jan 1, 2010

By Theodore von Rosenvinge

Large diameter (2.4 meter) drilled shaft foundations were installed to depths of over 62 meters through soil into Arkose bedrock for Connecticut?s Pearl Harbor Memorial Bridge (I-95 over New Haven Harbor). The project involved many ?firsts? including the first ?extradosed? cable-stayed bridge in the US, and for Connecticut, the deepest drilled shafts, the first use of a rotator to install shaft casing, and the first use of the Mini-Sid technology for rock socket bottom inspection. Design utilized both friction and end bearing for rock sockets. O-Cell testing was employed to maximize performance factors during design and to allow adjustments to socket lengths during construction. Favorable test results permitted a reduction in socket lengths and significant cost saving.

Jan 1, 2011

By A. V. Rose

A redevelopment in the City of London has been constructed with a piled foundation system that is believed to be the first of its kind. The purpose of the research is to explore this novel foundation method, which involves the installation of closely spaced piles in a perimeter arrangement with a body of soil enclosed in the centre. Both centrifuge modelling and numerical modelling techniques are used.

Jan 1, 2011

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

"Every year during the Transportation Research Board (TRB) Annual Meeting in Washington D.C., the Federal Highway Administration (FHWA) National Geotechnical Team (NGT) takes time to talk about what we are doing in research, training development and policy support. At times, I have jokingly referred to it as the State of the Program Address, but we do see it as an important opportunity to update our transportation partners on priorities and needs for the program.This update is really a snapshot of the program during the previous year, with a look at projects that are currently active. Activities undertaken by the NGT are funded from multiyear roadmaps maintained by the FHWA program and research offices, and reflect trends and opportunities affecting and influencing transportation geotechnics now and in the future. The roadmaps identify activities in research, development, guidance, technology transfer and training that will be accomplished by the NGT through and beyond FY 2020 in eight broadly-defined focus areas: • Extreme events, geohazards and sustainable geotechnics• Performance management• Reliability-based design and construction• Advanced geotechnical modeling• Alternative delivery methods• Design and construction optimization• Site characterization• Quality assuranceThe process to identify focus areas and to develop activities that will be addressed by the NGT is guided and informed through input from the FHWA NGT members, and considers feedback and input from State Departments of Transportation (DOTs), FHWA Division offices, industry and academia. This process is revisited annually to review not only the activities that are currently funded, or will be funded, but also to review the relevance of the focus areas with respect to the future needs of the FHWA, State DOTs and the transportation community.In 2016, the NGT was successful in delivering several products that will advance the state of the practice and that better support policy. Products developed included research reports, design and construction guidance, and training courses. In 2017, the research and program offices will continue to work on projects that fit within our prioritized plan and that positively impact the geotechnical community as a whole. A listing of recently completed and currently active projects is provided below."

Jan 1, 2017

By Ryan Law

Ground energy systems are being installed in increasing numbers in the United Kingdom. This is particularly true in London where planning regulations require larger scale developments to provide at least 10% of their entire energy demands from renewable sources. A common approach has been to use the groundwater from the Chalk aquifer as a source of energy. This paper explains the potential long and short term sustainability problems with groundwater based systems sited in central London (or any other urbanized area). It also outlines an approach to site testing and numerical modelling to ensure that the system functions well throughout its lifetime. This approach is then applied to a project located in central London.

Jan 1, 2008

By K. K. S. Ho

In Hong Kong the design of excavated piles in weathered granite has conventionally been based on a rule-of-thumb which relates the allowable base bearing capacity to the SPT N value, with no allowance for skin friction. This rule-of-thumb has been shown to generally lead to conservative designs. To improve the overall understanding of load-transfer mechanism of excavated piles in weathered granite, instrumented pile load tests have been conducted. This paper summarises a selection of instrumented pile load test data in Hong Kong and the observations made of the results, which indicate that there was considerable scatter in the back-calculated skin friction values. However, the mobilized skin friction was shown to be significant which can lead to substantial savings in design.

Jan 1, 1996

By Jeongbok Seo

This paper describes successful application of driven tapered-steel-pipe piles for two large-scale projects in the New York metropolitan area: Rego Park Mall, Rego Park, N.Y. and 164 Kent Avenue, Brooklyn, N.Y. The combination of side friction and end bearing resistance produced by tapered-steel-pipe piles has been well-recognized as greater than the side friction and end bearing resistance by pipe piles. Forty-four tapered piles were driven and tested at these two sites. Design pile load for the two sites was 260 kips for Rego Park Mall and 400 kips and 300 kips for 164 Kent Avenue. To measure the pile-drive hammer efficiency, the compressive stress in the pile, and to estimate the ultimate bearing capacity of the pile, dynamic load testing using a Pile Driving Analyzer (PDA) was conducted on index piles at the sites. Subsequent to the field testing, data analysis using the Case Pile Wave Analysis Program (CAPWAP) was conducted. Restrike PDA analysis and full-scale static load tests were performed on the selected test piles. Test piles at the project sites exhibited significant time-dependent increases in bearing capacity caused by the effects of "set-up" or "soil freeze." The dissipation of excess pore-water pressure in the soil, which had been disturbed and remolded by driven pile, was generally considered the primary cause of set-up. The increase at the subject sites ranged from 100 to 300 percent of the capacity measured at the initial driving. This paper discusses the results of various types of load testing on tapered piles and the set-up effects by comparing PDA test results acquired during and after pile driving. Finally, an empirical relationship for the New York metropolitan area has been offered for quantifying set-up.

Jan 1, 2008

By Kozo Takeda, Arashi Shimano

"Dry Jet Mixing (DJM) technique is widely known as soil mitigation technique with small ground displacement during installation comparing with other techniques. Some projects involving sensitive structures, however, require smaller impact than in conventional technique. In order to reduce ground displacement during DJM installation, this paper introduces systematic mixing technique, RD-DJM (Reducing Displacement – Dry Jet Mixing). RD-DJM is characterized by injection nozzle on the rim of mixing blade and fin plate on mixing shaft. These devices contribute efficient collection of injected air toward mixing shaft and result in reduction of ground displacement. The authors demonstrate successful performance of RD-DJM indicating difference between conventional installation and RD-DJM technique.INTRODUCTIONThe Dry Jet Mixing (DJM) method is one of the most common techniques in Japanese deep soil mixing field and characterized mechanical mixing of powdery binder with in-situ ground (dry-mixing technique). It is widely believed that DJM Method has great advantages in less quantity of binder to achieve the desired strength and less waste generation during installation.DJM method can meet the required strength with less binder content than wet mixing. And volume of binder of dry mixing is absolutely less than wet-mixing injecting considerable volume of binder slurry. This means that dry mixing causes less ground displacement compared with wet mixing.As the medium for forced feeding of the binder, the DJM method uses compressed air, which is blown from the mixing blade nozzles to scatter the binder and then recovered through the periphery of the mixing shaft to the ground surface. Because the binder is injected outward from the injection orifice at the root of the mixing shaft, a part of the air may escape to untreated areas due to the blockage of air recovery path around the mixing shaft. Figure 1 illustrates possible escaped air and leakage around installation location."

Jan 1, 2015

By B. Francis

Literature provides only limited information regarding the behaviour of laterally loaded piles socketed into weak rock masses. A laboratory program, comprising a number of tests of scaled models of the pile/rock mass system has been conducted. A synthetic rock, known as Johnstone was used to simulate a naturally weathered and fractured siltstone. The load-deflection behaviour of the test piles was measured, and strain gauges were fixed to the model piles to assess the bending moments. The laboratory results are compared with the results from several theoretical models, some of which are in the form of commercial software packages. This study highlights the inadequacy of existing methods to adequately model the influence of rock joint orientation in geotechnical design. Additionally, numerical modelling of the pile/rock mass system was carried out using the discrete element program UDEC. The importance in modelling the system using discontinuum mechanics is highlighted, particularly to capture the anisotropy of the rock mass.

Jan 1, 2004

By H. Mori

Construction of cast-in-place piles with enlarged bases has become popular in the cities in Japan facing to the sea coast, where the subground soil is soft alluvium deposited to depths often exceeding 30 m. The groundwater table is a few meters below the ground surface. Skin friction of piles may become negative due to ground subsidence or reduced due to liquefaction of loose sand during an earthquake. To support highrise buildings, depths of bearing strata to which piles are embedded often exceed 50 m. Due to such geotechnical conditions, methods and equipment to build cast-in-place concrete piles mainly built by the reverse circulation method have been developed since the 1970s. In the first half of this paper, the authors review the cur-rent practise of building cast-in-place piles with enlarged bases. Then they introduce the TFP system developed in recent years, and discuss about the procedures to control and monitor enlarging of bases.

Jan 1, 1989