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By Alan J. Lutenegger

Some years ago, a method was developed to incorporate a grout column around square-shaft helical screw-piles and anchors to increase shaft buckling resistance under compression loading. An additional benefit of this grouted shaft is to increase the load capacity in both compression and tension, depending on the geometry of the lead helical section and the soil conditions. Because of the unique construction procedure, the contribution of the shaft to the total capacity has largely been unknown. The behavior of grouted shaft helical anchors in clay was investigated by performing full-scale axial uplift (tension) load tests on a series of anchors installed at the University of Massachusetts Geotechnical Test Site. In order to isolate the contribution of the grouted shaft to the total load capacity, anchors were installed with a wooden dowel connection between the lead helical section and extension sections on three of the four anchors so that only the shaft resistance would be measured during the load tests. The grouted shafts ranged in length from 10 to 30 ft (3 to 9 m). Initial tests were performed approximately 5½ months after installation. Nearly four years after the initial tests were performed, the tests were repeated to evaluate any significant change in capacity with time and/or repeat testing (preshearing). The soil conditions at the site are presented along with the load-displacement curves for both the initial and repeat teats and a discussion of the analysis of the results. Repeat load tests showed an increase in capacity from the initial testing, however the percent increase was not the same for all depths. The results demonstrate that considerable shaft resistance can be developed in clays from the grouted shafts as might be expected. Depending on the L/D ratio of the shaft and the contribution of the lead helical section, at working loads the shaft capacity can dominate the behavior.

Jan 1, 2011

By T. Jason Hardell

The Victory Bridge project was contracted by the New Jersey Department of Transportation. The project included the construction of two 4000-ft precast segmental concrete bridges to replace the existing Victory Bridge that was built in the 1920's. The existing bridge was a swing span bridge that was in desperate need of replacement. The project was considered high priority due to the large maintenance costs to keep the swing span operating over the busy navigational channel. In March of 2003 construction began on the first bridge and by April of 2005 all of the segments were set for the second bridge. On September 5 of 2005 the second bridge was open to traffic. The total cost of the project was $110-million. The two new bridges required the construction of 24-eight foot and 32-six foot diameter-drilled shafts with rock sockets. All of the shafts were constructed in the tidal Raritan River working from barges. What will follow is a description of the construction techniques that were used to build these drilled shafts, the anticipated and unanticipated challenges that were encountered during the project, and the lessons learned.

Jan 1, 2005

By M. Mets

Pile foundations have been used in Estonia since the beginning of 1960's. To evaluate the capacity of piles nearly 2,500 pile tests and 1,800 pile loading tests Have been carried out. The pile foundations of nearly 150 houses are under settlement observations.

Jan 1, 2000

By Jan Pru?ka

This paper describes the sheet pile design for the Line C extension from Ládví station to the North of Prague. The first part of the paper describes the geological conditions and structural configuration of the project. Typical cross sections, the description of the construction stages, and monitoring are discussed. The second part of the paper focuses on the sheeting design method. It describes the method of dependent pressures, that is, how the pressures acting upon a structure depend on the deformation. The design process and verification methodology are described in detail with comparison of the results with in-situ monitoring.

Jan 1, 2011

By N. V. Nayak

Maharashtra State Road Development Corporation Ltd., has initiated a scheme for construction of 55 flyovers in Mumbai in India. To ensure speedier completion of projects several new technologies were adopted to save time without compromising on safety and reliability. Many of the flyovers involved large diameter pile foundations carrying loads ranging from 3500kN to 1375kN. Significant time would have been lost in using conventional load testing procedure to check pile capacity apart from the difficulty in mobilizing the load and the obstruction to site movement and traffic on the adjoining roads. High Strain Dynamic Testing was introduced on the project sites in lieu of static load testing after conducting numerous co-relation studies on various project sites. A total of seven co-relation studies have been conducted till date and based on these data static testing has been replaced by dynamic testing on numerous flyovers. The paper presents the results of such studies. CAPWAP analysis was also conducted on the data to evaluate the percent skin friction and end bearing so as to improve future design parameters.

Jan 1, 2000

By Franz-Werner Gerressen

"The use of soil improvement to utilize areas, which are not suitable for foundation purpose, has a long tradition. Due to the increasing demand of foundation works in areas of unsuitable soils, the improvement of the existing soils becomes even more important in the future.Various applications and systems for various demands exist around the world. Either it is a “simple” improvement for settlement reduction or a more important aim as liquefaction mitigation. However, each system has its advantages, limits and needs.Furthermore to the soil improvement, using various tools, soil mixing can also be used for applications like cut off and/or retaining wall.The paper will describe some basics of various techniques and different applications of the systems all over the world where the systems provided solutions for different purposes, e.g. simple foundation or liquefaction mitigation.It will describe also the main equipment which will be needed to execute these works under the various conditionsINTRODUCTIONSoil mixing is a methodology where the soil is improved by mixing it with cement, lime or other binders in situ by using a mixing tool. This methodology can be used either as wet mixing or as dry mixing. In the more frequently used wet mixing process, usually a mixture of binder and water, maybe with additives, is injected and mixed with the soil. Depending on the type of soil and binder, by the end of the mixing process, a mortar like mixture is created which hardens during the hydration process. In the dry mixing process, the binder is directly mixed with the soil and reacts directly with the existing soil and water.Mixing tools show several versions, so that they are mixing around either a vertical or horizontal axis, mixing in a trench and maybe are jet assisted. Figure 1 shows a classification done by Bruce 2010. Depending on the technique, improvement depth of up to 80 m can be achieved."

Jan 1, 2017

By Dan A. Brown

The following paper was written by Dr. Dan A. Brown, P.E. Brown is an Associate Professor at Auburn University's Department of Civil Engineering. The paper was originally presented at a FHWA's Transportation Research Board meeting and is presented here with the author's consent. Construction and design of drilled shaft foundations in hard pinnacle limestone requires flexibility from all parties involved due to the variability of the subsurface conditions. This article describes some strategies which have been found useful in the Birmingham, Alabama area. The importance of well trained and experienced field personnel in these conditions is noted. It is also vital that engineers understand the construction challenges so as to provide both quality assurance and cost effectiveness in design and in the specifications.

Jan 1, 1991

By R. L. Xu

In this paper, the author would like to point out with figures that the building industry is one of the key industrial sectors of the national economy in China. And in the coming 15 years, the output of building construction will not in the least decrease, but increase. The requirements for building standards, quality, functions as well as physical environment will also be higher along with the incessant development of the national economy and the gradual raising of people's living standard. China is a country with a vast territory and a great, variety of physical characteristics. The topographic and engineering geotechnical conditions are complex and varies considerably from place to place. Although, in recent years, encouraging progress has been made in building construction, there still exist many problems unsolved or even not explored at all, which we have to tackle in the future design and construction of foundations. Also reviewed in this paper are the achievements attained in the past thirty odd years and the challenge we will face in the foundation engineering field in China.

Jan 1, 2010

By Seth L. Pearlman

Pin Piles are small diameter high capacity drilled and grouted piles also called minipiles or micropiles. They are ideal for building foundations on sites with poor ground conditions, sensitive surroundings, restricted vertical clearance, or difficult access. They are also well suited to foundation underpinning, arresting ground movements, and increasing the capacity of existing foundations. The major factors for selection of Pin Piles are reviewed; drilling, grouting, and design fundamentals are summarized; and a major case history is presented for the underpinning of the 43 story elevator core at the recently opened Mandalay Bay Resort and Casino in Las Vegas, NV.

Jan 1, 2000

By Robert C. Rabeler

Soil and Materials Engineers, Inc. (SME) has utilized drilled cast-in-place (D-CIP) piles on a number of projects in the midwest. These foundation systems have typically consisted of drilling an 8 to 9-inch diameter borehole with a rotary type drill rig or driving a casing with a small hammer. A structural steel member is installed in the center of the excavated space, and the borehole or casing is grouted to complete the installation of the D-CIP pile. This type of piling system has also been called: mini-pile, micro-pile, or drilled-in pier. The capacity of these piles varies depending upon subsurface conditions, as well as the structural capacity of the pile. The structural capacity can be modified based on the size and yield strength of the structural steel member. SME has used the D-CIP piles for underpinning of lightly-loaded structures for a number of years. Steel brackets can be welded to the structural steel member in the center of these piles, and the bracket extended underneath existing foundations to provide proper foundation support. D-CIP piles have also been used for new construction where access was limited. Recently, SME had the opportunity of providing design as well as construction monitoring services for a unique project where these piles were used, but at much higher capacity. The project involved adding seven additional floors on top of a five-story building (total of 12 stories). New columns were extended through the existing building to support the new floors. Access to construct foundations was available to one level of underground parking beneath the structure, as well as to a basement area. Access required equipment to travel through a 3-foot wide hallway. A special duplex drilling machine was used to access the foundation locations and to install the piles in a limited headroom condition. Eight-inch diameter D-CIP piles were extended to a depth of approximately 40 to 50 feet below grade and socketed into a dense clay till or sandstone, and No. 18 or No. 20 threaded bars were installed in the center of these piles. The design pile capacity was as high as 190 kips and were verified by a compression load test. The load test was performed with limited access and headroom. These piles were installed by Spencer White and Prentis Foundation Corporation (SWP). For conditions where rock or hard soils are encountered at reasonable depths, D-CIP piles can provide working load capacities comparable to larger driven steel piles. The ability of the equipment to access very restricted areas, combined with the high capacities results in a very attractive solution to a number of difficult foundation problems.

Jan 1, 1999

By Rolf Katzenbach

The principle questions related to the design of deep foundations especially in soft soils are the stability and the cost optimised settlement reduction to prevent possible damages and to minimise the deformations of the adjacent infrastructure. The present develop­ments in the design of deep foundations lead to the design approach of the Combined Pile-Raft Foundation (CPRF) which offers a lot of new possibilities, e.g. the utilisation of the CPRF for horizontal loading or the use of the subsoil as a geothermal storage system.

Jan 1, 2006

By Balu E. George, Subhadeep Banerjee, Shailesh R. Gandhi

"A three-dimensional analysis of laterally loaded helical piles installed in cohesionless soil is presented. Finite Element Analysis was conducted using commercially available Plaxis 3D AE version, assuming Mohr-Coulomb failure for soil. Pile is modelled as plate elements with a single helical blade attached to a hollow shaft. The ultimate load for various configurations is examined considering deformation criteria. The Bending Moment distribution and maximum lateral deflection are also discussed. It was observed that the ultimate lateral load carrying capacity increased by presence of helical blade and the maximum deflection also got reduced. The diameter of the helical blade was found to have significant effect on the lateral deflection, maximum bending moment and the ultimate load. However, the observations from the study suggest that the presence of helical blade seizes to produce considerable effect after a certain depth. Difference in failure pattern with regard to the distribution of soil resistance observed for different geometries considered for numerical analysis are also touched upon.INTRODUCTIONHelical piles or screw anchor piles have gained popularity due to fast installation, instant use, and other advantages over the traditional piles. They are usually used to support structures like solar panels, light houses, and other light structures which are subjected to uplift loads. However, such structures are often subjected to significant lateral loads as well. Under lateral loads, the response of helical piles can be different from that of a conventional pile due to the presence of the bearing provided by the helical blade. However, the proper design remains a concern due to lack of work carried out on the lateral capacity of helical piles.The lateral performance of helical piles is significant because they can act as efficient alternative to conventional piling systems in many applications.The lateral load capacity of screw anchor piles with different number of helices were examined by Mittal et al. (2010) by experiments in sand. They found that the lateral load capacity of piles increases with addition of helical blades. Prasad and Rao (1996) examined the lateral capacity of helical piles in clay by experiments on model piles and found that the lateral capacity of helical piles were more than that of the straight shaft piles. It was observed that the lateral capacity increase with embedment depth and shear strength of soil. Sakr (2009) studied lateral performance of two section helical piles in soft soil. The investigation by Prasad and Chari (1999) reported that the pressure distribution across the diameter is not uniform for circular piles, but it is maximum at the centre and almost zero at the two edges.Puri et al. (1984) after conducting model tests on single-helix, two-helix, and three-helix anchors installed in sand, proposed a mathematical model that was fashioned after Matlock and Reese’s elastic theory model. Elkasabgy and Naggar (2015) investigated he lateral performance of full scale large capacity helical piles in structured cohesive soils and reported the modulus of sub-grade reaction to be non linear."

Jan 1, 2017

By Mario Terceros H, Bengt H. Fellenius

"ABSTRACTThe city of Santa Cruz, Bolivia, is historically dominated by houses and three to five storey buildings.The geology in and around the city is such that even very light buildings need to be supported onpiles. The recent increase of the Bolivian economy, notably that of Santa Cruz, has created a demandfor new residential as well as office and industrial buildings, which mostly consist of multi-storey orhigh-rise buildings with significantly larger foundation loads. Foundation piles have become largerand longer, and the load on individual piles is increased. The development has resulted in an increasein the demand for more sophisticated design and construction methods and stricter approach toverifying the quality of the construction processes and results.This paper describes to geology of the Santa Cruz region and how the geotechnical conditions areconsidered in the design and construction of piled foundations. The improvement of past constructionand design techniques, based mostly on bored piles constructed with bentonite slurry, is beingreplaced with new methods of constructing bored piles, e.g. the Full Displacement Pile (FDP) andincorporation of techniques such as enlarging the pile toe, e.g., with the Expander Body. This paperpresents the results of several full-scale tests and discusses the incorporation of the test results indesign and construction.1 GEOLOGY OF THE REGIONSanta Cruz de la Sierra is located in the eastern lowlands and sub-Andean zone of Bolivia, SouthAmerica. The area lies at an elevation of about +400 m and the geology is a Paleozoic (250 millionyears old) sedimentary basin. The soils of interest to civil engineering construction are quaternarywith the dominant minerals being calcite, silica and feldspar. The main agent is the Piray River and itstributaries. Their past meandering over the area has resulted in a sedimentation-erosionsedimentationprocess and a profile dominated by fine to medium sands with intermittent layers ofclay or clayey sand. With increasing distance from the river, the clay-containing layers are thicker.Fig.1.- View of Bolivia with location of Santa Cruz and map of Santa CruzThe upper about 15 to 18 m thick part of the profile consists of normally consolidated layers of clays,silts, sands, in various combination and thickness. Below, the soil is more homogeneous and consistsmostly of sand and gravel. The groundwater table lies typically at a depth of about 6 m in the highestpart of the city and at about 1 to 3 m depth in the lowest part of the city."

Jan 1, 2014

By Sangseom Jeong, Kyoungyul Kim, Jaeyeon Cho

"Abstract The lateral earth pressure of vertical circular shaft is investigated by using experimental tests and a theoretical analysis. The emphasis was quantifying on the magnitude and distribution of a lateral earth pressure measured by three-dimensional arching effect. A framework for determining the earth pressure distribution on the basis of both centrifuge model and full-scale field test results is introduced. Through these studies, it is found that the lateral earth pressure decreases within active displacement (dh/H: 0.2×10-2, dh: horizontal displacement, H: Height of vertical shaft) of wall at deep excavation and the arching effect is more significant for deep excavation than for shallow excavation. It is also found that the lateral earth pressure acting on a vertical circular shaft considering arching effect is 70% smaller than that calculated by Rankine theory, and thus represents a significant improvement in the prediction of realistic earth pressure for vertical circular shaft subjected to arching pressure.INTRODUCTIONIn South Korea, an increasing need for underground excavation and the application of the vertical circular wall (i.e. vertical shaft) is becoming an important issue in engineering practice. Here the vertical circular wall is generally embedded in soft or hard rocks through weathered soil varying thicknesses ranging up to 15 m. Since 1980, a number of huge excavation projects such as underground space for constructing power stations, subways, high-speed railways, and many lifeline constructions have been performed in urban areas (Jeong and Seo, 2004). Although there have been considerable advancements in construction techniques involving vertical circular wall, it is still very important for tunnel engineers to control the lateral earth pressure. Additionally, Proper estimation of earth pressures is a key factor in design of vertical circular wall. Because of three dimensional arching effects, i.e. convex arching and/or inverted arching, the earth pressure acting on a circular type of wall is less than other types. Thus, the vertical circular wall is generally used."

Jan 1, 2014

By Nuno Cruz

"The concrete overbreak estimation for bored piles provides the quantification of the shaft’s expansion beyond its theoretical volume. There are stability analysis methods that can be employed before and after concrete pour but as for the moment of decision, during pile cast, the most common method still consists in measuring the rising of the concrete level in order to compare its poured volume with the theoretical pile section volume. This is a determinant parameter to monitor, not only because it assesses the bored shaft stability but also because it represents a direct cost. When analyzing the estimation methods commonly applied on-site it becomes evident that these are often affected by human errors that lead to misleading results. The objective of this paper is to identify those errors and discuss a subject which is usually overlooked. As a general conclusion, it was ascertained that most errors derive from inaccurate volumetric data, working procedures and gauging equipment. By acknowledging these widespread practices deep foundations contractors will be in a better position to make informed decisions on how to correct and improve bored pile stability.GENERALBackgroundWhen executing bored piles, the estimation of its concrete overbreak allows a swift appraisal of the excavation stability during the drilling process. This is simply obtained from the proportion of the poured volume of concrete over the drilled shaft theoretical volume, as shown in equation [1].Where CO = concrete overbreak percentage, Vc = volume of poured concrete, Vr = pile’s theoretical volume. This calculation not only provides a general idea of the shaft’s expansion from its theoretical volume, but also the outline of the excavated column’s geometry. For the latter, the outline will be as accurate as the number of measurements taken for each partial known volume of poured concrete. This means that for each load placed inside the excavation there is a corresponding rising of the concrete level. The profile of the definite pile is then plotted (see Fig. 1) and allows inferring about how stable remained the shaft walls up to the moment of casting.The technological developments in this area have provided other methods for determining pile stability before and after pile cast, such as ultrasonic echo sensing, cross-hole sonic logging or thermal integrity profiling systems. Notwithstanding, concrete overbreak assessment remains as common practice and confers the advantage of providing stability information during the process of pile casting."

Jan 1, 2017

By Bernard H. Hertlein

All methods of deep foundation construction present challenges to the contractor and engineer that vary according to the method employed, and the geotechnical conditions in which it is being used. Augered-Cast-In-Place (ACIP) piles are generally regarded as one of the most challenging, because the construction method precludes the use of traditional shaft inspection and quality control techniques. Application of Nondestructive Test (NDT) methods can provide quality control for ACIP shafts that traditional methods cannot, but each NDT method has limitations. These make some NDT methods unsuitable for use on ACIP shafts, and may limit the effectiveness of others, depending on geotechnical conditions. To help contractors and engineers working with ACIP piles select the test method most appropriate to specific site conditions, this paper presents a summary of the major NDT methods currently available, and reviews their capabilities with respect to the unique conditions presented by ACIP pile construction. Case histories illustrate how a combination of careful method selection, skilled data interpretation, and experienced engineering judgment have resolved problems and ensured quality in foundation construction by discriminating between potentially serious defects, and those that are unlikely to be significant.

Jan 1, 1997

By Bruce Haldeman

Timber has been used as pile support for structures for 6,000 years. Some means of preservation of wood go back almost that far. Timber piles support all types of structures ? some are buried below the water table; others raise a home for protection from animals or a chief's home for prestige. Millions of wood piles have been driven for bridge support. Earlier piles were driven by hand then by ingeniously raised weights. Charring, animal fats and oils have been used for preservation. Coal tar creosote and other preservative methods started only in the early 1800's and give effective protection.

Jan 1, 1984

By Kirk A. Mcintosh

Augered, cast-in-place (ACIP) piles have been utilized in the United States for a wide range of projects since the 1950's. Due to the cast-in-place nature of the installation method (and lack of a driving criteria); however, ACIP piles have not been readily accepted by some practicing geotechnical and structural engineers. Since ACIP piles were initially developed, the installation equipment and techniques have been improved and refined and the number of experienced contractors has significantly increased. Over the past 10 to 15 years, the pile type has experienced significant growth in the United States (particularly in Florida) because engineers have become more knowledgeable and comfortable with its use. The Miami area, in particular, has experienced considerable growth in the utilization of ACIP piles primarily due to their usage on the $1 billion Miami Metrorail System project in the early 1980s. The economic advantages over other deep foundation types, coupled with some unique installation advantages, have shown that ACIP piles can be a viable foundation alternative on many projects. Even though ACIP piles have gained respect in the private sector, the pile type has generally not been readily accepted by government transportation agencies. The reluctance to readily accept this foundation type stems primarily from the quality assurance aspect of cast-in-place pile construction. Additionally, there has not been much research activity on this foundation type, technical papers, formal associations (other than the DFI), or a concerted effort to standardize the industry. This paper serves to discuss the state of practice for ACIP pile installation in the state of Florida.

Jan 1, 1997

By Robert Fernie

Demographics and Infrastructure demands have led to a significant increase in construction of: deep basements for buildings and, trough structures for Highway and Rail/Metro. Concrete embedded walls used for temporary works can be incorporated into permanent works and because of this (and geological conditions) tend to be favoured in UK. This paper considers British practice in the provision of diaphragm (slurry) walls secant (true and pseudo) piled walls contiguous piled walls Plant utilisation, construction techniques, reinforcement placement, connections, propping, water tightness, tolerances, general UK practices and their relation to design practices are discussed. [ ]

Jan 1, 2000

By Martin van Staveren

In today's rapid changing construction world, the business pressures on piling and deep foundations reach sky-high levels. Ever increasing complexity of construction projects do severely contribute to these business pressures. Projects are often constructed in densely populated areas and located close to vulnerable buildings and infrastructure. The inherent uncertainty of ground conditions plays a dominating role in these foundation projects. Effective risk management is a key success factor for profitable and sustainable operations of piling and deep foundations. It starts with a fundamental requirement to be aware of risks. Next the different risk perspectives of all stakeholders in any foundation project have to be acknowledged. A simple and structured risk management approach is introduced, to demonstrate that effective risk management is not necessarily that complicated. A major element is the contractual allocation of risks, as a result from differing ground conditions. It is based on the so-called Geotechnical Baseline Report (GBR). The main objective of the GBR is to provide a clear contractual arrangement for the allocation of risks, arising from differing site conditions. The benefits of explicit risk management in general and contractual risk allocation in particular are illustrated with an example and experiences. The presented structured risk management approach, including contractual risk allocation, is still rather new. It proves to be promising for cost-effective risk control of piling and deep foundation projects, anywhere in the world.

Jan 1, 2006