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By John N. Cunningham

Despite the wide use of micropiles for rehabilitating and retrofitting existing structures, little is known regarding the load-transfer distribution of grouted micropiles in various soil deposits. The rehabilitation of a concrete-frame warehouse in Portland, Oregon, required provisions for the seismic restraint of a new shear wall; the installation of two micropiles was specified to meet project requirements. The micropiles were uncased, 19-m (63-ft) long, 200-mm (8-in) nominal diameter, and reinforced full-length with a 64-mm (No. 20) diameter hardened steel threadbar. Due to space limitations, a sacrificial, instrumented micropile was installed near the two production piles to verify design assumptions. This paper describes the geologic setting of the project within the unsaturated Missoula Flood deposits, instrumentation, load-displacement behavior, load transfer, and Beta-coefficients for the sacrificial micropile.

Jan 1, 2011

By P. Davies

The Hillside Smelter presently under construction at Richards Bay, Republic of South Africa, will be, on completion, the fifth largest aluminium smelter in the world. The site selected for this plant is underlain by sandy soils of variable density to depths of 30m or greater. In order to firmly establish pile founding depths required for alternative pile types in the variable subsurface conditions prevailing across the site, a pre-construction test piling programme was conducted incorporating piles instrumented with resistance strain gauges. The results allowed analysis of the relative contributions of end-bearing and shaft friction to the overall bearing capacity of each pile type and permitted comparison with the predictions of conventional static bearing capacity analyses. Conformance with acceptance criteria in respect of allowable pile head movements for single piles was also examined.

Jan 1, 1996

By Rasin Duzceer

In this paper, the results of pile load test on 24 piles from twelve sites are presented. The pile load tests were performed on 14 driven and 10 bored piles of varying diameters and lengths installed in different ground conditions in Turkey, Saudi Arabia and Kazakhstan. The purpose of this study is to evaluate and compare the axial capacity of the piles obtained using pile load test interpretation methods. Davisson, Brinch Hansen %80, Chin-Kondner, Shen-Niu, De-Beer, Housel, Mazurkiewicz, Fuller-Hoy, Brinch- Hansen (90%), Corps of Engineers, Butler Hoy and Tangent Intersection methods were used to determine the axial capacity of the piles. Static analysis using FHWA method was performed to predict the axial capacity of the piles. A statistical analysis was performed to compare and quantify the load test interpretation methods. The ratio of interpreted (Qi) to predicted (Qp) pile capacity was compared for each method. For each pile load test and for each interpretation method, the mean and coefficient of variation of (Qi)/ (Qp) were calculated. Among twelve methods investigated, the highest Qi/Qp value was obtained as 1.37 for Chin-Kondner method whereas the lowest Qi/Qp ratio of 0.70 was obtained from De Beer method.

Jan 1, 2002

By J. Wennerstrand

Slender steel piles have found an increased use in Sweden in resent years. These piles are often driven throw soft normally consolidated clay to refusal in till or at the rock surface. In contrast to most other piles the bearing capacity with regard to failure of the shaft is in many cases smaller than the bearing capacity with regard to failure of the soil or rock at the lower end of the pile. Imperfections such as deviations from a straight line of the pile centerline and residual stresses in rolled and welded profiles are important for the capacity of the pile shaft. Even thow the second order moment caused by initial deviations in piles is only half of that in a column with the same slenderness, imperfections can and should be accounted for in much the same way as for columns.

Jan 1, 1989

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 Evelio N. Horta

The influence of soil improvement replacement area in foundation settlements is discussed for soil improvement methods used in Southeast Florida. A 3D Finite element analysis is used for two typical conditions in the area: foundations bearing on loose sands and foundations bearing on a crust of limestone underlaid by very loose sands. Particular attention is given to Jet Grouting as a soil improvement method. The potential impact of the stiffer jet grout columns on the structural foundation design and quality control issues are also discussed. It is shown that in loose sand conditions 15 to 20% area replacement produces substantial reduction in total settlements. Reduction in total settlements for mixed profile is less significant but the use of the method in those cases is directed to reduce punch through potential.

Jan 1, 2007

By Mandy Korff

Walls consisting of CFA-piles are often used for vertical cut offs for building pits. Several methods of installation and geometry may be used and sizes, depths and strengths of walls necessary vary widely. Based on experience with secant CFA-pile walls in The Netherlands, requirements for this type of wall can be set with a risk management view to it. This paper describes those requirements, based on specific local conditions.

Jan 1, 2006

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 D. Waite

The Chairman opened the session by wondering why so few papers on Maritime Structures had been received for this conference. Perhaps because the marine environment is so hostile and the access so difficult that engineers tend to be more prudent about new ideas and designs. Dennis Waite noted the number of grey hairs in the room - grey hairs which could be equated with experience gained the hard way. He hoped that this experience would be passed on in the discussion period of this session. The Chairman was delighted to welcome two authors from China, Mr Sun and Mr Liang. He was most grateful on behalf of the conference for their efforts both in preparing their papers and for being able to present them. He regretted that Messrs Noce and Fedolino were not able to present their paper and then welcomed Mr Christensen from Denmark who would present the first paper.

Jan 1, 1991

By Timothy C. Siegel

In response to a solicitation for ground improvement for the construction of a new hospital in Owensboro, Kentucky, the team of Berkel & Company Contractors and Dan Brown and Associates PC designed and installed lightly reinforced cast-in-place piles (known commercially as Cast-in place Ground improvement Elements or CGEs) as part of a composite ground system. The concept of the design is that the structure load is shared between the piles and the soil subgrade. The load sharing is controlled (to some degree) by the placement of a cushion between the pile head and the bottom of the overlying spread foundation. In an effort to confirm the design principles and to better understand the behavior of composite ground, the design-build team performed plate load tests on ground with a single CGE and with a group of CGEs. The small plate test (on ground with a single CGE) characterized the stiffness of the cushion. The large plate tests showed that the cushion will distribute the applied load to the CGEs and to the soil subgrade between the CGEs. On the basis of the plate tests, it was concluded that the plate stiffness can influence the test results. The use of a concrete layer was effective at supplementing the plate stiffness. The cushion was shown to be an important component of a composite ground system by allowing mobilization of the soil subgrade resistance and avoiding a stress concentration at the tops of the CGEs that would otherwise be present if the spread foundation and piles were rigidly connected. Because the composite ground system engages the resistance of the soil subgrade, the structural demand is reduced and consequently there is a potential for savings when compared to a conventional pile foundation. Several foundations for the new Owensboro hospital are being monitored for vertical movement during construction of the superstructure that will extend through 2011. At the time of this paper (mid 2011) the settlement of the foundations due to only part of the structural load (primarily the structural steel) has been negligible.

Jan 1, 2011

By Maurice Guillaud

The most striking innovations on diaphragm-wall construction plant are those associated with continuous real-time trajectory monitoring of the excavating tool (either a grab or a hydro-cutter). The recent equipments are fitted with clinometers and gyrometers to control deflection, rotation or deviation from the vertical, thus allowing to install diaphragm-walls with a verticality accuracy of less than 0.3%. One of the greatest advantages of extensive use of on-board IT systems on the Hydrocutters and hydraulic grab machines is that it aids quality control by automatically producing complete real-time reports of all excavating data (verticality, depth, type of ground, rate of progress, stoppages, etc.). These reports are available to the Engineer, providing the total transparency required for Works Supervision and the Quality Assurance Plan. They also provide the Contractor with input data for databases used for optimising efficiency and progress criteria on future jobs.

Jan 1, 2002

By Matthew C. Pierson

Due to space limitations for transportation projects, many times sound walls must be constructed above mechanically stabilized earth (MSE) walls. These sound walls must resist lateral loads from wind or impact and must therefore be constructed on drilled shafts passing through the reinforced fill for the MSE Wall. Current design methods for the drilled shafts are believed to be overly conservative. Full scale lateral load testing of three foot diameter shafts contained within and solely supported by a 20 foot tall MSE block wall was conducted and the lateral capacity was evaluated. Shafts were tested individually and as a group. The data collected from full scale testing was then used to calibrate numerical models. This paper contains a discussion of how the facing type and stiffness affects the behavior of the numerical model as well as selected comparisons between the actual test data and selected model simulation results.

Jan 1, 2009

By H. Mori

This paper describes a new borehole loading test using a self-boring instrument appropriate for dense sandy soils and stiff clayey soils. The results of loading tests for the bearing strata of deep foundations according to this method are also presented. This method has been applied to the study on the settlement behavior of heavy foundations resting on dense sand, stiff clay or soft rock in Japan.

Jan 1, 2010

By Serhat Baycan, Mikias Yohannes

"Kuala Lumpur Karst is a complex limestone formation that is characterized by presence of cavities, solution channels, pinnacles and floaters. Basement excavations in such geological formations are usually challenging, mainly owing to the unpredictable rock head depths and potential for groundwater inflow. Any excavation support system should have adequate robustness and water tightness. Traditionally, Secant Bored Pile walls (SBP) with struts are the preferred option for karst ground. This paper discusses a cost effective and innovative alternative solution for a particular site – using Deep Soil Mixing (DSM) and using Contiguous Bored Piles (CBP) together with Ground Anchors (GA). The site, located around one of the busiest areas of Kuala Lumpur, is a 5,700 m2 commercial and residential development. A 16.0 m deep excavation was needed for four levels of basement and excavation support along the 275 m perimeter of the development. Within the site, the depth to rock head varied from 6 m to 19 m. The basis for each solution and conditions for its suitability are discussed in detail. Some design considerations and construction challenges are also presented. The performance of the two retention systems during excavation are presented, together with comparisons versus design predictions. Suggestions for future development are also given. Advantages of this approach compared to other traditional approaches are highlighted.1. INTRODUCTIONThe geology of Kuala Lumpur is among the most complicated and geotechnically challenging formations in South East Asia. The majority of the city falls into the Kuala Lumpur Limestone formation; which is a thick, highly-weathered and cavernous limestone. This formation is pure calcitic to dolomitic in composition, having infrequent schist and phyllite interbedding (Gobbett et al., 1973).The KL limestone has a highly karstic topography dotted with cavities, ravines, interconnected subterranean channels, pinnacles, overhangs, floaters and slump zones (Tan, 2006). This results in erratic bedrock profiles even within short distances. It is not uncommon to see a precipitous rock head incidence within short distances in the same site. In most parts of the City, the bedrock is typically encountered ranging from very shallow depths to about 30.0 m. The exception to this is at the heart of the City, where Kenny Hill formation prevails above the KL limestone. In such cases the limestone bedrock can be encountered much deeper. The erratic rock head profile and the highly karstic nature of the KL limestone makes it a geotechnical challenge requiring careful consideration of suitable engineering solutions.1.1 – Site DescriptionThe site, located in downtown Kuala Lumpur, is abutted by a busy street on the North. Before development, the site previously served as a car park. To the west an access road separates the site from an empty lot; while on the east, the lot is bounded by light weight residential and commercial buildings. On the south side, the site is bordered by a road that separates it from a prominent Shopping Mall in the City. A layout plan and an artist’s impression of the finished development is shown in Figure 1."

Jan 1, 1900

By Michael Perlow

Helical screw piles in use since 1838 are routinely used for energy, transportation, municipal, industrial, marine and coastal infrastructure as well as for excavation support, environmental remediation, and foundation repair. They are especially well suited for work in constrained areas, renovations and structure retrofits. Helical pile design procedures over the past 10 years have gone through a remarkable evolution with the establishment of the 2007 AC358 Helical Pile Acceptance Criteria and inclusion of helical screw piles in the 2009 International Building Code (IBC). New 2009 IBC building code requirements and AC358 Acceptance Criteria are presented along with advances in helical pile design procedures, installation, QA/QC, and recommended load test verification criteria. Use of helical smart piles to validate helical pile design and verification of ultimate pile capacity is highlighted.

Jan 1, 2011

By Mustapha Zergoun

This paper presents the results of load tests to assess the vertical load carrying capacity of concrete expanded base piles, or pressure injected footings, for various projects located near Vancouver, British Columbia, Canada. The site subsurface conditions and load test methods are described for the Vancouver International Airport site and the test results are reviewed under both compression and tension loading conditions. The pile load tests at Vancouver International Airport are compared to load tests at other sites near Vancouver. The pile load test results are reviewed with respect to available methods of estimating the vertical capacity of this type of piles. The effect of ground improvement by densification on the load test results is considered. The limitations of tension load tests on single piles with respect to uplift resistance of pile groups under seismic conditions are pointed out. Recommendations are proposed regarding pile load test methodology to estimate ultimate vertical load carrying capacity of plies for limit state design.

Jan 1, 2004

By Hugo Meggitt, Damian R. Siebert, Wystan Carswell

Excavation-induced ground movements are a critical component in the design and construction of deep excavations in urban settings due to the potential adverse effects on adjacent structures and infrastructure. Ground movements are influenced by soil stratigraphy, soil properties, adjacent structures, and construction means and methods. The use of empirical relationships, computer models, and reliance on experience with similar excavations in similar soil conditions often provides a basis for predicting excavation-induced ground movements. In this paper, data from 21 deep excavations approximately 20 ft to 75 ft deep supported by concrete diaphragm “slurry” walls in the Greater Boston area are compared to published literature, considering how different foundation systems (e.g. shallow foundations, caissons, and piles) of abutting structures have been affected by adjacent excavations. The influence of construction method (conventional vs. top-down) on adjacent foundation movements indicate that top-down construction typically results in smaller foundation movements. INTRODUCTION Estimation of ground movements due to excavation is a challenging endeavor, even with complex three- dimensional finite element modeling and high-order constitutive models that are increasingly available in modern engineering practice. Aside from the expense of the soil exploration and testing used to inform these higher-order models, the challenges of modeling past stress history, adjacent structures, and the groundwater conditions during excavation require not only large investments of time during design but also validation from past experience (to avoid a “garbage in, garbage out” paradigm). While site conditions such as soil stratigraphy, soil properties, groundwater conditions, and as-built conditions of adjacent structures can be obtained, measured, and estimated, the effects that means and methods of construction have on ground movements are difficult to quantify. During early phase design, assessments of predicted ground movement are unable to account for all aspects of project construction, nor is it cost-efficient to fully design an excavation while project parameters such as site size and excavation depth are under consideration by the design team. While construction is in progress, benchmarking support of excavation performance and associated ground movements in the context of successfully completed projects allows for a more nuanced view of system performance and provides the opportunity for more informed decision-making (if required) as construction proceeds. For these reasons, the use of empirical relationships and the collection of historical support of excavation performance holds high value for the practicing geotechnical engineer at all phases of the project.

Jan 1, 2019

By James W. Niehoff

"Prior to 2003, most high rise structures in Honolulu, Hawaii were supported on driven pile foundations, extending through shallow coral strata and bearing in competent formations at depths of 100 ft (30 m) or greater. In 2003, the 40-story Hokua Tower became the first building in Hawaii to use continuous flight auger (CFA) piles for support. These piles derived most of their capacity from side shear in the shallow coral formations, which reduced their required lengths to less than 100 ft (30 m) sand significantly increased their capacity. Not only did CFA piles prove to be more efficient and cost-effective than driven piles, but the reduced noise and vibration associated with their installation made them and drilled piers the foundations of choice for most mid- to high-rise projects going forward. Because drilled foundations were new to Hawaii, it was necessary to develop effective design parameters for the unique soil and rock conditions found within this urban area. While drilled foundations were found to have many advantages over driven piles, construction techniques had to be modified to compensate for extensive voids in the coral formations. This paper presents a compendium of the data derived from numerous full scale, instrumented load tests conducted during the past decade and provides guidance for the design and installation of CFA and drilled pier foundation systems in areas having geologic settings and history similar to that of Honolulu.INTRODUCTIONThe State of Hawaii is one of the most remote areas in the world, lying nearly 2400 miles (3800 km) from the nearest continental land mass. In spite of this vast distance, the population of the islands has grown to over 1 million people, the majority of whom live within and in close proximity to the City of Honolulu on the Island of Oahu. The city is densely populated with over 400 high rise apartments, condominiums, hotels and office buildings located within 5 miles (8 km) of the city center (Fig.1). Nearly all of these buildings have been constructed within the past 50 years."

Jan 1, 2016

By Willie M. NeSmith

The use of drilled (screwed) displacement piles is an emerging sector of the United States deep foundation industry. During installation of these systems, a Ko to Kp environment is created in the materials surrounding the pile immediately prior to casting, and this condition results in increased shaft and toe resistance in soils where displacement leads to densification. Current continuous flight auger and drilled shaft design methodologies in the United States assume a Ko to Ka condition in the vicinity of the pile, and are thus an inappropriate starting point for static capacity analysis of drilled displacement piles. This paper examines constructability issues, and the sensitivity of performance to installation, and offers an empirical design methodology for drilled displacement piles. The proposed design process has been based on evaluation of 40 load tests, primarily in granular materials, and in a variety of geologic settings, and includes modification for soil types within the coarse-grained range.

Jan 1, 2002

By Arash Khosravifar

The seismic design of extended pile shafts for the combined effects of dynamic shaking and liquefaction-induced lateral spreading is investigated using nonlinear dynamic finite element analyses (NDA). Results of NDA parameter studies are used to illustrate how inertia and lateral spreading loads combine during shaking. The NDA results are used to evaluate equivalent static analysis (ESA) methods. Implications for design practice are discussed.

Jan 1, 2010