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By Hamed Ardalan, Mohamed Ashour

"CHAPTER 1INTRODUCTIONThe use of piles to stabilize active landslides or to prevent instability in currently stable slopes has become one of the most important innovative slope reinforcement techniques over the last few decades. Piles have been used successfully in many situations in order to stabilize slopes or to improve slope stability, and numerous methods have been developed for the analysis of piled slopes (Ito et al., 1981; Poulos, 1995; Chen and Poulos, 1997; Zeng and Liang, 2002; Won et al., 2005).The piles used in slope stabilization are usually subjected to lateral force through horizontal movements of the surrounding soil; hence they are considered to be passive piles. The interaction behavior between the piles and the soil is a complicated phenomenon due to its 3-dimensional nature and can be influenced by many factors, such as the characteristics of deformation and the strength parameters of both the pile and the soil. The interaction among piles installed in a slope is complex and depends on the pile and soil strength and stiffness properties, the length of the pile that is embedded in unstable (sliding) and stable soil layers, and the center-to-center pile spacing (S) in a row. Furthermore, the earth pressures applied to the piles are highly dependent upon the relative movement of the soil and the piles."

Jan 1, 2013

By Muhannad T. Suleiman

The design of deep foundations supporting heavy buildings, bridges, transmission lines, and highway structures, is governed by lateral loads in many cases. However, due to the use of empirical or semiempirical approaches to develop the soil force-displacement relationships (i.e., p-y curves), a wide range of recommendations are presented in the literature. Recent efforts by the author and co-workers enabled simultaneous direct measurements of soil-pile interaction pressure and lateral movement along the pile length, resulting in p-y curves based on direct measurement. Advanced sensors including sheet pressure sensors and shape acceleration arrays were used in these experiments. The experiments were conducted at the Soil-Structure Interaction (SSI) facility funded by the Major Research Instrumentation Program at the National Science Foundation. This paper focuses on the SSI of single laterally loaded piles. The test pile was 101.6 mm in diameter and 1.42 m long, which were installed in well-graded loose sand. This paper provides a summary of the installation and testing procedures, soil properties, pile instrumentation, measured lateral load-displacement response, strain profile along the pile length, lateral movement along the pile length and the pressures measured at the soil-pile interface. Furthermore, the paper presents measured p-y curves compared to estimated p-y curves using empirical methods available in the literature.

Jan 1, 2011

By M. Hesham El Naggar, Maged A. Abdlrahem

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

Jan 1, 2016

By Bill Zietlow

A micropile and soil nail underpinning system was installed to support a building immediately adjacent to a 25-ft deep excavation in downtown Salt Lake City, Utah. Both the building and the underpinning were instrumented to monitor deflections, rotation and crack growth. The underpinned structure consisted of a two story concrete masonry unit (CMU) building founded on shallow spread footings attached to a concrete high-rise building on spread footing two floors below grade. The face of the excavation was 10 in. in front of the underpinned building foundation wall. The underpinning system consisted of small diameter hollow bar micropiles installed with injection grouting techniques below the bottom of the excavation and attached to the underpinned structure by a concrete pile cap doweled into the existing footing. The lateral loads imposed by the soil under the underpinned structure were designed to be supported by the soil nail wall installed through the micropiles during excavation. The settlement monitoring instruments consisted of crack gages, optical survey prisms, high sensitivity vibrating wire water levels and biaxial vibrating wire tilt meters. They recorded maximum movements of approximately 0.1 in. of settlement, 0.05 deg. rotation (top of wall rotating away from excavation) and up to 0.08 in. of crack opening during the excavation until one month after the soil nails and shotcrete facing were completely installed. This movement was well within both the estimated settlement and the estimated settlement tolerance of the underpinned structure.

Jan 1, 2008

By Daniel Levacher

Pile load tests in site require extensive means of action and time. To get outstanding tests, the environmental test conditions must be perfectly known and acceptable. They concern the support installation, the loading, the access and instrumentation site conditions and the economical aspects. In particular cases as offshore areas, the load tests are not feasible. Moreover the variability of soil characteristics limits the interpretation results at the considered tested site. The use of centrifuge modellling offers an other way to study the loaded pile behaviours. Centrifuge tests lead to parametric approaches which constitute for geotechnical engineers an important data base tor recommendations and design codes. To accurately simulate pile behaviours by checking similitude laws linked to the studied problems, the installation of model-piles must be also representative of the in-situ piles. Driven piles account for a large part of the piles installed through the world, mainly for offshore or harbour constructions. So, to explore driven pile problems by centrifuge tests, miniature pile driving hammers must be developed and tested under macro-gravities. The paper describes two types of these ones in details. They are commonly used at the centrifuge centre of the Laboratoire Central des Ponts et Chaussées - (LCPC) - [Réf. 1] for different deep foundations researches. Performances and limitations are given for both miniature pile drivers and some results from their use are presented to illustrate the suitability of these apparatus.

Jan 1, 1996

By Cau T. Bui

Thanks to Doi-moi (renovation) policy, many great bridges were constructed in Vietnam to meet demands of her booming economy in the recent decade and deep foundation structures were the only alternatives for the foundations of these great bridges. The deep foundation structures were constructed by modern technologies and almost of all these deep foundation structures were designed by foreign companies and carried out by Vietnamese workers and engineers under supervision of foreign experts. Beside successes, there were several failure cases in which the collapse of temporary scaffolding system of Can-tho Cable ? Stayed Bridge due to settlement of its pile foundation killing 54 workers and seriously injuring 80 other workers was the most serious. This paper introduces construction techniques of the deep foundation structures applied to building of great bridges in Vietnam recently. It will especially focus on two failure cases: 1) collapse of temporary scaffolding system of Can-tho Cable ? Stayed Bridge due to settlement of its pile foundation and 2) failure of drilled shaft foundation of Thanh-tri bridge due to poor construction technique and management. These two failure cases were greatly concerned by both bridge specialists and the public. Reasons of and lessons from these two failure cases will be carefully discussed. From the two failure cases, this paper will draw some lessons that should be important issues to be seriously paid attention when designing and constructing deep foundations in Vietnam.

Jan 1, 2008

By Wolfgang G. Brunner

In the far north of Uttar Pradesh Province in the Indian Himalayas, the 280 MW Dhauliganga hydroelectric power plant is under construction by National Hydroelectric Power Corporation (NHPC), a state- owned enterprise, and a joint venture of Kajima Corporation of Tokyo and Daewoo Corporation of Seoul. This project sets out to develop the lower section of the mountain cascade of the Dhauliganga River, a tributary of the Sarda River, with a 311 m gross head. The 1360 km2 mountainous catchment area is bounded in the north- east by the Chinese border and in the south- east by the Nepalese border. The dam project is located in a remote area north of the principal town of Darchula of the upper Sarda valley, which is one of the seismically most active regions of India. The 56 m high rock fill dam, which will be the first of its kind in India, is faced with concrete and has a 1 m thick, at its crown 270 m long and over 70 m deep cut- off wall of plastic concrete below its toe. The cut- off wall, with a total area of 7500 m2, is constructed by a combination of Bauer hydraulic grabs, assisted by chisels and a Bauer BC 40 cutter which enables the overlapping joint system to be installed, guarantees optimum verticality and enables the cut- off to be keyed into the bedrock formation.

Jan 1, 2004

By Gianni O. Chieruzzi

A 400 MW, gas-fed power plant on floating piles and piled raft foundations was constructed in the Province of Moskovskaya, Russia in 2008. The subsurface is characterized by fill underlain by loose to medium dense alluvial deposits, with peat and clay interbeds, a stiff to hard, highly plastic, silty clay stratum of glacial origin, and a stratum of very dense, varved interbeds of sand and silt. More than 800, drilled concrete piles were constructed at the site. The pile length ranged from 15 to 23 meters below existing surface grade, and the pile diameter ranged from 0.9 to 1 meter. Initial analyses by others predicted total power plant settlements of 3 to 4 cm when subjected to the permanent loading conditions. Under a peer review process for the equipment supplier, subsurface investigation and testing were performed to verify the consolidation parameters used for foundation design of the power plant foundation. The parameters obtained in this investigation were used in the 3-D finite-element model ELPLA as inputs for the settlement analysis of the turbine building and power island. The ELPA analyses predicted settlements on the order of 7 cm over a period of 30 years. The actual settlements after two years of monitoring were compared against the model predictions. The rate of settlement and the recompression index were both underestimated in our model. The measured settlements have enabled us to calibrate both of these model parameters so that the model better matches the data.

By W. G. K. Fleming

Mr P. Bermingham introduced paper 9.1, describing the development and trials of a new pile load-testing technique that the Authors had termed "Statnamic". The system involved launching a test weight mounted on the head of the pile by igniting chemical fuel in a pressure combustion chamber between the pile head and the test weight. The expansion products from the burning fuel generated large pressures which were used to launch the weight upwards at high velocity. The reaction from this force generates an equal and opposite force at the pile head. This force is typically of much longer duration compared with, for instance, dynamic load testing by drop hammer. In addition the pile experiences a much lower acceleration - typically of less than one g. Because of the long duration blow, the pile is loaded at below its natural frequency and is therefore under a uniform high stress over its full length throughout the duration of the test. The pile behaviour is not dominated by the complex action of an impulsive stress-wave as with standard dynamic testing. The test technique is thus essentially quasi-static. It was anticipated that a ram test weight of 16 tonne would be sufficient to provide the test reaction for a 600 tonne load test. It was pointed out that the device was still at the research stage, but had yielded encouraging results to date. Testing would proceed from model testing and computer simulation to full scale field testing.

Jan 1, 1991

By Ramdane Bahar

The new Algiers airport building is a reinforced concrete building of more than 80 thousand square meters of floor slabs. It is located at Dar-EI-Beida, near the old passenger terminal, about 20 km east of Algiers. The project is designed to receive about six millions passengers annually and leaves the possibility of future extension. Due to the presence of a top layer of compressible soil and great concentrated loads transmitted to the foundations, the building is to be founded on 1730 bored piles of 1.2 meter diameter varying in length between 14 and 28 m. Construction work started in 1986 and was interrupted in 1996 due to financial difficulties when the structure was almost complete. The structure was left unattended for more than three years without any weatherproofing and in 1999 a new firm was appointed to complete the work and hence an evaluation of the existing structure was necessary. This paper describes and discusses the foundation design, construction supervision, site quality control and assessment by the parallel seismic method of the deep foundations built in cohesive soils. The variation in soil conditions and identified geotechnical and hydrogeological problems associated with the development of the area, required a thorough knowledge of the soil conditions. A variety of tests, involving more than 200 locations, were carried out. The ground investigation, pile tests as well as different problems encountered during piles construction, are presented.

Jan 1, 2002

By Dharmil Patel, Michael J. Chow

"Construction progress is nearing completion at a Brownfield Site for a 100,000sf mixed-use 10 story building plus cellar for Silver Star Motors including a two-floor pre-owned Mercedes Benz showroom; high-end residential rental studios, 1, 2, and 3 bedroom apartments; and penthouses on the upper two floors. Excavation through impacted soil extended to 15ft depth. Project is approximately 7 ft north of a NYCT subway station, portions of the SOE are within inches of a 6ft diameter NYCDEP Sewer, and cellar extends below the depth of adjacent structures, requiring over 200 lf of underpinning.A complex series of earth retention systems was utilized consisting of underpinning, drilled-in soldier piles (micro-piles), timber/concrete lagging, soil anchors and inclined rakers supported by a partially constructed foundation mat. Foundation mat subgrade was approximately 4 ft below the groundwater level creating more challenges during underpinning and achieving suitable foundation subgrades. All construction was undertaken on a non-union basis.This paper describes the design, construction, and lessons learned for the multiple earth retention systems, Brownfield Remediation requirements, instrumentation, and monitoring used to manage complications of building adjacent to an active subway station, in close proximity to existing utilities, with underpinning and mat foundation installation below the water table.Results of the instrumentation program are summarized which utilized an AMTS, monitoring prisms on adjacent structures, automated seismographs, and manual NYCT surveys."

Jan 1, 2016

By Saba Mohan

This study presents results based on the Pile Installation Demonstration Project (PIDP) that was conducted as a part of the East Span San Francisco-Oakland Bay Bridge Seismic Safety Project. For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was estimated and compared with results of other methods currently available in the literature for predicting the soil pile set-up rate.

Jan 1, 2002

By Kyle M. Rollins

To improve our understanding of lateral resistance of pile groups, a series of lateral load tests were performed on a full-scale pile group using both static and dynamic loads. The pile group consisted of nine 0.6 m-diameter steel pipe piles driven into clay. During the static tests, the load was cycled fifteen times to evaluate the drop in lateral resistance that would occur due to repeated loading and the formation of a gap. The peak load typically decreased by about 15% from the initial cycle to the last cycle. The load carried by each pile was also measured and there was a significant drop in resistance for the piles in the trailing row relative to the leading row. The dynamic force was applied using the Statnamic loading system which produced a lateral force of 3500 kN (787 kips) in about 0.1 seconds. In two cases, dynamic loads were applied following application of 15 static load cycles. In these cases, the dynamic lateral resistance was about the same as the static resistance, likely due to gaps around the pile. In three other cases, the dynamic force was applied prior to the cyclic loading. In these cases, the dynamic resistance was 30 to 60% higher than the static resistance. Simplified analyses suggest that the difference in resistance could be attributed to damping produced by the soil surrounding the piles during the virgin loading.

Jan 1, 2002

By W. Morgan NeSmith

The city of Kansas City, Missouri, is replacing its original airport, con- structed in 1972 as a "drive-to-the- gate" facility, with a modern, single- terminal facility with just over 1 million sq ft (92,903 sq m) in area along with an adjacent 6,300-space parking structure. It is the largest infrastructure project in the city's history. The project team designed and oversaw the installation of 12-24 in (305-610 mm) diameter augered cast- in-place (ACIP) piles to a range of depths with the pile toes located in underlying alluvial clay, weathered shale or on intact limestone, depending on the required loads at each column location. The specific ACIP piles used were auger pressure grouted (APG) piles. Additional information regarding the ACIP pile installation process can be found in the Augered Cast-in-Place Pile Manual, Third Edition (2016) prepared by the DFI Augered Cast-in-Place and Drilled Displacement Pile Committee. This article includes a summary of the subsurface conditions, the foundation support requirements, the extensive performance test program - started before production installation but not completed until well into production phase of the project - and the resulting production pile installation require- ments. The approach resulted in about $700,000 in foundation program savings to the city. The reduced con- struction time of about 10% less than originally estimated also added to the overall savings beyond the direct foundation savings.

Oct 1, 2022

By Hyunsuk Yoon, Kiho Lee, Juhyng Lee, Younghoon Jung, Junboum Park

"The environmental double pile method is presented as a device to improve the engineering properties and to clean up contamination of low-permeability soil. This method is one of the novel technologies based on the concept of one step process. It can be applied to low permeable contaminated ground for site reuse. It uses piles to improve drainage, contaminant remediation, and bearing capacity of the ground. To evaluate the on-site applicability of this technology, drainage and strength properties of the environmental double pile were assessed by a series of experiments and numerical analysis. Environmental double pile was found to be a feasible alternative method to improve contaminated soft ground.Korea is a peninsula with many coastal industrial zones. These zones are located in regions mostly underlain by soft ground with low permeability and adjacent to industrial areas that can be contaminated. Therefore, a new region-specific remediation method is required to achieve environmentally sustainable development. This research introduces the Environmental Double Pile (hereinafter, refer to as EDP) for the lowpermeability contaminated ground and focused on both contaminant remediation and soft ground improvement. Basically, the EDP is quite similar to sand compaction pile (SCP). The SCP has been studied extensively to improve soft ground (Braja 1999; Hansbo 1994; Madhav and others 1978; Taylor 1948). But unlike SCP, EDP is filled with oyster shells instead of sand and an inner pile is inserted in the center of this oyster shell filled-zone. Therefore, it is a double pile consisting of the oyster shell pile and the inner pile, as depicted in Fig. 1."

Jan 1, 2005

By Mark Spence, Tom Lardner, Matthew Janes

"IntroductionThe design-build method streamlines project delivery through a single contract between the Contract manager and the design-build team. The design-build method places emphasis on collaborative project management between design and construction disciplines to minimize project schedule, reduce costs, encourage balance risk amongst the design-build team. Since 1985, the percentage of nonresidential design and construction projects has increased from 5% to 45%.1A project carried out in Edmonton, Alberta, Canada will be used as an example to illustrate the challenges of the design-build project delivery method and the merits of establishing a GBR. The project involved a complex slope stabilization as part of an extensive freeway widening. At the project location the roadway was being widened within the base of a historic stream valley into a steep slope with a history of a previous slope failure. The slope was to be steepened through the installation of a series of 14 interlocking arc structures constructed half way up the slope. Access and schedule proved critical to the successful completion of the project.Geotechnique and Site HistoryThe geotechnical investigation undertaken for the site included six boreholes drilled at the crest of the slope to depths ranging from 14.5 m to 30.2 m. Laboratory testing of the soil samples included direct shear tests, Atterberg limits and grain size analysis. The geotechnical report also referenced a previous geotechnical investigation that was carried out in response to a failure of the slope in 1971."

Jan 1, 2015

By Paul M. C. B. M. Cools, Martin Th. van Staveren

In 2010, the 5-years joint industry programme Geo-Impuls started in the Netherlands. The ambitious goal of this programme is to reduce geotechnical failures in our civil engineering projects by half in 2015. In the Geo-Impuls programme over 40 client organizations, engineering firms, contractors, research institutes, and universities are involved. In a risk-driven way, and based on top risks and dilemmas, the participants defined three central development themes. These themes are (1) contracts, for dealing with legal issues, (2) geo-engineering, for dealing with technical issues, and (3) communication, for paying attention to differences in risk perception by the human factor. In total 12 Working Groups contribute to these themes by producing one or more specific tools. These provide practical solutions for how to deal with contractual, geotechnical, and communication issues. The tools include working processes, guidelines, best practices, as well as some instruments. The development of these tools, as well as the available results, will be presented in this paper. From the start, Geo-Impuls embraced geotechnical risk management (GeoRM) as the risk-driven way of working for geotechnical engineering and construction. Over the past years, GeoRM and its supporting tools were already successfully applied in several projects. Therefore, the paper also describes also the GeoRM implementation process, including the quality assurance and control. Finally, the effectiveness of GeoRM will be discussed, by summarizing an analysis of all published geotechnical failures and accidents in construction projects in the Netherlands, which decreased substantially over the past 4 years.

Jan 1, 2017

By Brian McGlynn

There are many factors that can result in a site characterization being limited. For example, a client may undervalue the importance of a good geotechnical report, or an owner may feel that it would take too much time to perform an appropriate investigation among other reasons. For this project, neither was the case. The challenge was that the construction sequence of work required wick drains to accelerate the settlement of soil that had yet to be placed, resulting in the need to create a wick drain bid package based on unknown settlement parameters. This wick drain project took place in Long Beach, California, at the Long Beach Middle Harbor Re- development. For much of the past decade, the Port of Long Beach undertook a $1.5 billion redevelopment of two outdated terminals to create the Long Beach Container Terminal (LBCT). To achieve this goal, the existing terminals were demolished and the slip that serviced one of the older terminals was designed to be infilled to create the new area that would allow for the LBCT to manage 3.3 million TEUS (a commonly used freight term meaning twenty-foot equivalent unit) of cargo each year. Ultimately, the construction of the LBCT would be performed under multiple contracts to allow the new terminal to begin operation in a phased approach. Menard performed the wick drain installation under two out of three contracts, and this case history focuses on the challenges anticipated and faced under the second of these awarded contracts.

May 1, 2023

By Kyle L. Murrell

Along the southeast United States coast, clayey silt and silty clay marine formations may cause pile installation and integrity problems. More specifically, excess pore pressures which develop in these soils during driving can cause high displacement piles to rebound or ?bounce?. Bounce is defined as a large (¾-in. to more than 1-in.) downward pile displacement during the hammer blow with little to no net displacement at the end of the blow. Pile bounce can generate damaging tension stresses and result in inefficient pile installation. A case history is presented where pile bounce was observed during the installation of 20-in. square ?high displacement? prestressed concrete piles which support a new ferry terminal in coastal North Carolina. High-strain dynamic pile testing was performed during test pile installation to evaluate driving stresses, pile capacities, and hammer performance. During and after installation of numerous production piles, circumferential cracking was observed on some of the piles. Additional high-strain dynamic pile testing was performed on two piles installed with a hammer having a heavier ram than the initial hammer. The new driving system generated lower tension stresses and installed the 20-in. piles more efficiently. Low-strain integrity testing was performed on the piles to qualitatively assess the cracks and locate any unidentified cracks. The low-strain testing was performed on piles installed at least a week prior to testing and on piles installed immediately prior to testing. When low-strain testing was performed immediately after pile installation before dissipation of excess pore pressures, pile integrity could be evaluated to depths of at least 12 pile diameters deeper than when performed weeks after installation.

Jan 1, 2008

By David R. Black

Foundation problems due to collapsible and expansive soils are well known throughout the arid western United States. Millions of dollars are spent annually to counteract the effects of such soils for both new foundations and existing foundations suffering from settlement or heave. Over the last 20 years helical screw piles have come into wide-spread use as a permanent deep foundation element for these problem soils, especially in the arid western United States where, in some areas, they are a standard of practice. Independent research resulting in recognition by every national building code in the United States has legitimized helical screw pile technology. Once thought of in terms of light structural underpinning, helical screw piles of today are designed to take heavy structural loads, vertical and lateral, tension or compression, including seismic loads. With proper pile grouping, design capacities for column loads over 4,500 kN (1,000 kips) are attainable. This paper discusses design considerations specifically dealing with collapsible and expansive soils: soil investigation parameters, predicted settlement and long-term creep, heave in expansive soils, downdrag in collapsible soils, shaft slenderness buckling, maintaining shaft alignment during installation, refusal condition, water migration along the shaft, lateral loading, cyclical loading for seismic loads and machine foundations, corrosion, helix durability during installation, the installation torque vs. capacity equation, and design methodology. The paper concludes with several case histories where helical screw piles were used for new structural foundations and to underpin existing failed foundations in St. George, Utah, Cedar City, Utah, and Denver, Colorado, USA, sites of some of the most expansive clay and collapsible soil in North America. Soil descriptions and performance histories are presented.

Jan 1, 2002