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By Tony Amis

There is very limited information relating to the potential impact of temperature cycles, outside the variation that occurs naturally, on the behaviour of foundation piles. Such thermal loading occurs when piles are used as heat exchange elements within a Ground Sourced Heat Pump system, in addition to carrying building loads to competent strata. An investigation has been undertaken where a conventional load test has been extended to include a period in which the load is maintained and temperature cycles applied. Instrumentation was installed in the test pile, an adjacent borehole, two of the anchor piles and the heat sink pile in order to be able to develop an understanding of the temperature variation and associated strain changes within and between the various elements. Conventional electronic strain and temperature gauges have been used in conjunction with optical fibre sensors which also measure strain and temperature changes. The results have confirmed the validity of the assumption made in the thermo-dynamic design of the system, the compatibility of the differing measurement systems and differing installation methods for the optical fibres, and initial assessment suggests that the load-settlement response of the pile is not adversely affected by the temperature cycles applied.

Jan 1, 2008

By Joshua R. Omer

A numerical model is developed for predicting the load transfer and settlement behaviour of vertically loaded, bored cast in-situ piles. Based on analysis of full-scale pile tests, closed-form equations are formulated to uncouple the shaft and base transfer resistance components of the pile/soil system. Appropriate parameters are introduced to take into account: (i) the shaft resistance distribution in unlined and partially lined piles, (ii) the effects of ?soft toe? (voided toe pile) behaviour on base resistance development. For convenience, an interactive computer program has been developed in Matlab? with a user friendly interface system. The program can be applied to predict the complete load-settlement curve and axial force distribution in bored cast in-situ piles if reliable soil test data are available. To demonstrate its validity, the proposed method is applied to 4 test piles, which are also analysed using two previously published methods: (a) elastic solution method and (b) layer discretisation method. Methods (a) and (b) above are based on load transfer (t-z) and finite element models respectively. It is shown that the proposed method yields axial force distributions and load-settlement curves that are in good agreement with the observed pile test data.

Jan 1, 2010

By Kyle A. Kershaw

The City of Grand Forks, North Dakota obtains drinking water from both the Red River and Red Lake River through a system of raw water intakes, shallow pipelines, and pump stations. However, during flood events, the City often loses access to the system, as evidenced during the record flood event in 1997. As a result, the City decided to construct a new gravity raw water intake system, including a pump station at the base of a 65-foot-deep, 60-foot-diameter caisson, behind a new levee system. Because of high design flood elevations and connectivity of river head to underlying soils, uplift resistance was required for the caisson. A total of 37, 2-foot-diameter, augered cast-in-place (ACIP) piles were chosen to provide uplift resistance. Because of the difficulties associated with installation of piles within the confined space of the constructed caisson and basal stability concerns, installation was completed from the existing ground surface to a depth of 120 feet. Several design and construction issues arose, including squeezing ground during pile installation, placement of long reinforcing bars, and installation of a dual material pile. A dual material pile was required to ensure that the ACIP pile below the base of the caisson was structurally sound and the pile above the base of the caisson could be easily excavated during sinking of the caisson. This paper discusses the solutions to each of these issues, as well as construction sequencing, load testing and integrity testing of the ACIP piles, and the successful completion of the project.

Jan 1, 2003

By R. A. Fraser

Large diameter (1.0 to 2.5m) bored piles have been widely used to support buildings and elevated roadways in Hong Kong. Most of these piles are founded on a hard bearing stratum such as granitic or volcanic bedrock, in the newly reclaimed areas along the water-front, the bedrock stratum can be as deep as 70-80 metres below ground surface, and construction of bored piles to bedrock in this case is difficult and unjustified. Nevertheless, Building Ordinance Regulations in Hong Kong require piles to be founded on bedrock. To overcome this problem for elevated roadways, trial piles have been designed founded on dense, completely decomposed granite. A number of piles have been constructed and subsequently load-tested to allow the rate of mobilisation of skin friction to be measured. This paper outlines the design, construction and testing method, and comments on the test results from several trial piles. GEOLOCICAL CONDITIONS The geology of Hong Kong consists predominantly of acid volcanic rocks intruded by granite. The granite has been deeply weathered, and variations in sea level have produced a drowned coastline with sequences of alluvial, colluvial and marine deposits overlying the weathered bedrock. Reclamation has extended this coastline. Typical site conditions are described later in the paper.

Jan 1, 2010

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

By Md. Nafiul Haque, Murad Y. Abu-Farsakh, Chris Nickel

"This paper presents the results from a pile load testing program for a bridge construction project in Louisiana. The testing includes two 54-inch open-ended spun cast concrete cylinder piles (OECP), one 30-inch open-ended steel pile (OESP), and two (30-inch and 16-inch) square prestressed concrete (PSC) piles driven at two locations with very similar soil conditions. All the test piles were instrumented with vibrating wire strain gauges to measure the load distribution along the length of the test piles and the skin friction and the end bearing were derived from strain gauge measurements. High strain dynamic load tests (HSDLT) were performed on all test piles at different times after pile installations to quantify the amount of setup with time. Static load tests were also performed on the PSC and open-ended steel piles. Due to expected large pile capacities, the statnamic test method was used on the two open-ended cylinder piles. The pile capacities of these piles were evaluated using various CPT methods (such as Schmertmann, De Ruiter and Beringen, LCPC, COFS methods). The result showed that all the methods can estimate the skin friction with good accuracy; but not the end-bearing capacity. Setup was observed for all the piles, which was mainly attributed to increase in skin frictions. The setup rate parameters “A” [The “A” parameter is defined as the rate of increase of pile capacity ratio (Rt/Rto) per log cycle of elapsed time] were back-calculated for all the test piles and the values were between 0.31 and 0.41.INTRODUCTIONDue to greater efficiency (capacity to weight ratio) of the pipe piles, open-ended piles are a viable option to solid piles. However, the behavior of open-ended piles is more complicated compared to the close-ended piles owing to possible formation of “soil plug” inside the open-ended pile. Many researchers have analyzed the behavior of both types of piles for different purposes; however, very few studies in the literature offer the side-by-side comparison of the close-ended and open-ended piles."

Jan 1, 2017

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 Pratter P., Boley C.

Polymers are well established in geotechnical applications, for example in ground improvement, where the polymers act as a binder that, when cured, holds the grains together by adhesive and cohesive forces. The subject of this research work is an innovative composite of polymers and gravel, which differs from conventional grouting materials due to its adjustable material properties. With these specific properties, the semi-rigid material can be optimally adapted to the local ground conditions and the individual framework conditions of a construction project. For the characterization of the composite material, stateof- the-art methods, such as image processing by segmentation, are presented. Segmentation is suitable for quality assurance and monitoring of laboratory samples and soil samples directly from ground improvement on the construction site. The load-bearing capacity of the innovative material can even be increased to the order of magnitude of concrete. For this reason, the soil mechanical laboratory tests in this research had to be modified and even expanded by rock mechanical laboratory tests. Based on the experimental investigations, the importance of this innovative material for practical application is demonstrated by a calculation example from construction practice, which shows that even difficult ground conditions can be handled with it.

May 1, 2022

By Rouzbeh Afsharhasani, Moses Karakouzian, Brandon Kluzniak

"The Vegas High Roller is the centerpiece of a new development parcel adjacent to the Las Vegas Strip. At a height of 550 feet, the High Roller is currently the tallest observation wheel in the world. The design team conducted a geotechnical site investigation to characterize the alluvial soils and cemented layers encountered and to provide foundation design recommendations for the observation wheel, boarding platform, and temporary structures needed to erect the wheel structure. This paper presents a case history of the geotechnical design process, including development of a ground model and design parameters, high-strain dynamic axial load tests, and settlement monitoring during construction. Results indicated that design parameters were conservatively assumed and that the majority of the axial load was transferred to a near surface caliche layer, thereby resulting in insignificant settlement of the foundation system.IntroductionThe engineering of the Vegas High Roller is similar in concept to that of the London Eye and the Singapore Flyer. The wheel has 28 cabins, each with a capacity of 40 persons. The top point of the structure is 550 ft above ground level at the site.A geotechnical site investigation program was undertaken and subsequent analyses were performed to provide foundation recommendations for the observation wheel legs, boarding platform columns, and temporary structures directly associated with construction of the observation wheel."

Jan 1, 2017

By Frank Borda

Two recent projects were completed in Ontario, Canada for major hospital additions that involved excavation support of heritage masonry structures. Conventional continuous caisson wall schemes were replaced, with significant cost savings, by tied back shotcrete systems. Using a combination of conventional design and FLAC analysis, excavation support was designed to permit excavation in competent to weak soils that limited horizontal movements of the existing structures to between 3 and 8 mm. The use of vertical wall elements (micropiles) integral to the shotcrete wall to support both the vertical wall loads and the face of the excavation was deemed to significantly reduce lateral and vertical wall movements. FLAC analysis was used successfully to predict wall movements and optimize design. The shotcrete method proved to be flexible and adaptable to design changes during the project. This permitted convenient accommodation of changes to the building geometry after excavation support had commenced. In addition the method accommodated staged demolition and excavation support of portions of the existing structure at low cost, conveniently and without delays.

Jan 1, 2004

By James P. Hambleton, Anastasia Nally

This work focuses on the numerical simulation of multi-plate anchor systems (e.g., helical anchors) in sand subjected to vertical loading. In assessing the stiffness and capacity of these multi-plate anchor systems, full awareness of the abilities and limitations of the various analysis methods must be understood. This work first summarizes studies completed by others and then goes on to assess the failure mechanisms of multi-plate anchors in sand and the influence of (1) plate width-to-depth ratio, (2) number of plates, and (3) relative positioning of plates. The analysis makes use of (1) conventional limit analysis, (2) so-called modified limit analysis that employs reduced strength parameters to account for the influence of soil dilatancy, and (3) the displacement-based finite element method, which considers elastic as well as plastic deformation leading to failure. The work critically reflects on limitations in the current analysis methods for helical ground anchors. INTRODUCTION Helical anchors are a relatively low cost foundation type, typically consisting of a steel rod and single or multiple plate attachments. In recent decades, they have seen rapid growth, and as outlined by Merifield and Sloan (2006) and Hambleton et al. (2014). Design techniques for helical anchors have previously been predominately empirical, as much of the past research in this field is experimentally based. It is common practice for helical anchors to be modeled as horizontally oriented plate anchors in both numerical and experimental analysis. This work focuses on analysis based on the finite element method, including so-called finite element limit analysis and the conventional displacement-based finite element method, with some comparisons made to experimental studies. Numerical simulation of anchor pull-out capacity in cohesionless soils is stunted by the many difficulties faced when using numerical analysis with cohesionless soils. Additional variations can be seen when comparing the serviceability based load capacities to the ultimate load. In this work, both the force-displacement response (stiffness) and the ultimate anchor capacity are assessed, with more focus on the latter. This work focuses only on analysis techniques for multi-plate anchors with vertical loading in cohesionless soils. Many studies have been completed in this area, some of which assume a rectangular plate in a plain strain model (Rowe & Davis, 1982; Merifield & Sloan, 2006; Cerfontaine et al., 2019). Whereas others use axisymmetric conditions (Baker and Kondner, 1966; Saeedy, 1987; Murray & Geddes, 1987; Ghaly & Hanna, 1994; Sakai & Tanaka, 1998; Merifield et al., 2006;) and minimal studies considered both axisymmetric and plane strain in the one study (Vesic, 1971; Tagaya et al., 1988; Murray & Geddes, 1987; Sarac, 1989).

Jan 1, 2019

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 Alexandra Weidle, Seffen Leppla, Rolf Katzenbach, Matthias Seip

"A lot of different deep mixing systems have been developed in the last decades for a wide spectrum of applications, e.g. retaining and foundations systems, soil improvement, sealing of toxic substances or dyke strengthening. The paper will deal with special aspects of constructions with deep mixing systems for infrastructures like soil improvement for cyclic loadings and underpinnings in difficult soil conditions by presenting cases from engineering practice.1. DEEP DRY SOIL MIXING FOR SOIL IMPROVEMENT OF RAILWAY TRACKS IN VERY SOFT SOILS1.1 IntroductionRailway tracks are set into vibrations by train passing. In very soft soil this leads to long-term deformations which lead to speed limits, temporary closings and big maintenance efforts. The energy of the dynamic loading is transmitted into the soil by compression and shear waves and at the surface by rayleigh waves (Wood 1968). The expansion of the waves are influenced by•,thickness of the soft soil layer•,density of the soft soil layer•,stiffness of the soft soil layer•,saturation of the soft soil layer•,frequency of the dynamic loadingThe frequency of the dynamic loading depends on the train velocity and the distance of the wheels and wheel sets. If the frequency of the dynamic loading is in the range of the natural frequency of the soft soil layer the vibrations increase extremely (Lieberenz et al. 2003). As a result the long-term deformations will increase as well.To avoid these long-term deformations and the resulting operation restrictions and maintenance efforts an adequate soil improvement is necessary. For the optimization of the soil improvement field tests have been carried out.1.2 Experimental field testsThe field tests have been carried out at a 300 m long test track with five different setups, each 30 m long:•,test track TS 0: no soil improvement•,test track TS 1: soil improvement with single lime-cement-columns 5.9 m deep (Figure 1a)•,test track TS 2: soil improvement with single lime-cement-columns 5.9 m and 10.4 m deep (Figure 1b)"

Jan 1, 2015

By Boo Hyun Nam, Berk Turkel, Luis G. Arboleda-Monsalve, Jorge E. Orozco-Herrera

Construction of buildings, roads, and traffic activities generate vibrations to urban infrastructure. The vibrations produced by construction activities have an impact on the soil through which they are transmitted. These effects become much more significant in granular soils. The soil conditions in Florida consist mainly of sandy soil deposits and this makes driven piles a commonly used method. In the design of deep foundation installations, it is significant to consider the potential construction issues related to the driving process. This process generates vibrations in the surrounding soils and thus, its effects on nearby soils and structures must be considered. This paper presents a web-based survey conducted among geotechnical engineers in Florida to better understand the common practice and experience regarding the effects of pile driving on surrounding soils and structures. The perception of different practitioners in the state of Florida on ground deformations and damages to adjacent structures induced by deep foundation installations are investigated. The engineers who have experienced ground vibrations and deformations were asked to define the susceptible soil conditions and main triggering factors of large ground deformations induced by pile driving. Sandy soils with loose to medium relative densities were found to be the most susceptible soil condition to generate ground deformations. Conclusions are drawn regarding the importance of considering ground vibration monitoring during the design phase of deep foundations.

Oct 1, 2022

By Lawrence Piccagli

This past spring of 2006, BENCOR installed the concrete reinforced diaphragm walls for the COSMOPOLITAN RESORT & CASINO in Las Vegas, Nevada. The project highlights include the excavation of approx. 326.000 square feet of reinforced diaphragm slurry wall with a thickness of 30 inches and a depth of 100 feet using three reverse circulation trench cutters (hydromills) at the same time. The reinforcing steel cages were fabricated on the 8 acre jobsite and approximately 12,000 cubic yards of 4500 psi concrete was placed via tremie. The jobsite logistics of coordinating three trench cutters and three separate desanding/slurry plants as well as the reinforcing steel fabrication and concrete placement all under a very tight schedule was quite challenging. A second main exercise was the execution of a temporary excavation support. As the excavation depths extends between 66 and 72 feet, five to six rows of temporary tieback anchors were required. Anchor lengths range from 43 -83 feet at a maximum design load of 235 kips.

Jan 1, 2007

By Abolfazl Eslami, Fatemeh Rostami, Sara Heidarie Golafzani, Mohammad Arabameri

Collapsible loess is classified as problematic soil found in most continents. The loess immediately collapses under stresses induced by axial compressive loading or the soil weight when exposed to moisture. In Iran, vast areas of the Golestan province are covered with aeolian loess deposits. This paper investigates whether the simultaneous effect of inundation and pre-loading in helical pile installation are operative and effective in improvement of Golestan loess. The effect of installation conditions on loess collapsibility is studied via two main approaches, i.e., field investigations and physical modelling. The experimental studies include installation of eight single helix piles in the Amirkabir University of Technology Frustum Confining Vessel, i.e., FCV-AUT. Also, four single helix piles with embedment depth of 3 m and diameter of 250 mm were installed in Golestan province and full-scale pile static loading tests were performed. The results indicated that the simultaneous application of crowd loading and water pressure during installation of helical piles results in better soil shear strength parameters. Moreover, high crowd stresses or low crowd stresses accompanied by water pressure during pile installation brings about similar load-displacement behavior of model piles installed in FCV-AUT and full-scale helical piles.

Oct 1, 2022

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which are 2.5 m to 3.0 m (8 to 12 feet) in diameter and extending over 60 m (200 feet) in depth below grade. There are unique challenges associated with constructing such large and deep cast-in-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

Jan 1, 2008

By Dennis Nottingham

Increased interest in seismic soil liquefaction and preventative soil stabilization sets the stage for improved deep compaction methods using pile driving techniques. In 1971 L.B. Foster Company personnel patented a method of deep compaction using a vibratory pile hammer and pile probe. The technique had some success, but did not produce consistent results and thus found its way to obscurity. Other patents attempted to modify the technique by various probe modifications, but again without measurable improvement from a practical point of view. Solutions to economical deep compaction up to 100-foot depths particularly in saturated granular soils would have a great impact on the construction industry and new bulkhead structures being developed, thus PND was prompted into related research and development. The advent of higher horsepower vibratory hammers, coupled with PND engineers' experiments, observations and measurements, led to an "H" pile probe design which has produced measured soil density improvements up to 250% using SPT "N60" values as a measure. Case histories of two projects involving extensive SPT soil sampling comparative measurements will be discussed along with findings that led to the compaction success. Applications to numerous modern "Open Cell" bulkhead projects will be presented and discussed.

Jan 1, 2004

By Martina Balic

Dynamic properties of the drilled shaft foundations supporting Doremus Avenue Bridge were determined by forced vibration testing. The main objectives of the substructure testing at Doremus Avenue Bridge were: (1) site evaluation with respect to the dynamic soil properties, and, (2) shaft evaluation for the purpose of definition of their dynamic stiffness. The site characterization entailed crosshole testing for the purpose of evaluation of the shear modulus profile. The drilled shaft impedance evaluation was done through forced excitation using an electromagnetic shaker. The responses of the tested shaft, as well as the response of adjacent shafts, were measured for the purpose of evaluation of the shaft interaction. To gain a better insight into the shaft dynamics, one of the shafts was instrumented with five triaxial geophones distributed along the full length of the shaft. The scope and results of the site characterization, shaft impedance and shaft interaction evaluation are presented.

Jan 1, 2004

By Ali Porbaha

In today's fast-track construction environment, owners are searching for non-conventional technologies to build their projects faster and safer while maintaining traffic flow during construction. To that end designers and contractors are providing solutions that incorporate many unique features to expedite construction processes. In addition to timely delivery of the finished highway products, there is an increasing interest in making the initial investment in applying innovative technologies and thereby minimizing costly maintenance of highway projects. Accordingly, the aim of this paper (along with the accompanying paper) is to examine innovative technologies, developed mostly in Europe, that accelerate construction of highway, runway and railway embankment foundations. For each technology, a basic concept, installation technique(s), and design considerations are discussed, along with the case history of a real-world project. The Geotextile Encased Columns (GEC), AuGeo, and Continuous Flight Auger (CFA) are presented in Part I. Deep Mixing (DM), Cut-Mix-Injection (FMI), Mass stabilization, and Combined soil Stabilization with Vertical columns (CSV) technologies are discussed in Part II.

Jan 1, 2002