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By P. D. Arumairaj, B. Vani

"Micropiles are small diameter cast insitu reinforced grouted piles and it has been effectively used in many applications of ground improvement. It increases the load carrying capacity of soil and reduces the settlement. It is also used in strengthening existing foundations. In this study, the effect of Solid and Hollow micropiles on the load carrying capacity of footing resting on sand is studied. The effects of solid Micropiles are investigated by conducting experimental model studies. The parameters involved in this study include the position of pile, pile length and pile spacing. Load test was carried out on a model footing resting on sand with solid and hollow micropiles. Load test trail is repeated for footing on Micropiles with varying lengths of 10, 20, and 30 times the diameter and spacing equal to 5, 4, 3, 2 times the diameter. The load-settlement behavior of each case is compared. Optimum length and optimum spacing of both the solid micropile and hollow micropile are determined. It is also observed that the effect of micropiles in the peripheral of footing resists lateral displacement of soil underneath the footing. The micropile beyond significant depth becomes redundant.INTRODUCTIONA micropile is a small diameter (less than 300 mm) drilled and grouted pile that is typically reinforced - FHWA-NHI 2005 (Federal Highway Administration-National Highway Institution). It is constructed by drilling a borehole, placing a steel reinforcing element into the borehole and grouting it. Hollow micropiles are typically reinforced by solid central bar that occupies about onethird of the hole volume. The grout is placed by gravity, under pressure methods or by a combination of both (post grouting). Thus, micropiles can be considered as small drilled-shafts that are specially drilled and grouted.Historically, micropiles have been introduced in Italy as a foundation system mainly for retrofitting and underpinning of structures that had sustained damage during World War II and access for conventional piling equipment was not possible (Bruce, 1988). The second generation of micropiles is a pressure grouted piles with a central mono all thread bar (with diameter up to 89 mm). They are installed by using either an open or cased hole drilling method.A new generation of micropiles, termed Grout injection bore micropiles (IBOR), was developed in the 1980s. The IBOR, currently named hollow bar micropiles, utilizes a continuous all-threaded hollow steel bar as the drilling and grouting conduit, which allows drilling and grouting simultaneously without the need of a casing during drilling. A sacrificial (lost) bit with openings that allow for pressure grouting of the hole is threaded onto the end of the hollow bar and is left in place following drilling. A drilling fluid (air, water, or grout) is introduced through the hollow bar and allows the spoils to flush from the borehole opening. Upon reaching the required depth, neat cement grout is then injected under high pressure into the drilled hole to fill the annulus between the bar and the soil from the bottom to the top. Due to the grouting method employed, the shape of the hollow bar micropile is expected to have a bulb shape with an enlarged base."

Jan 1, 2015

By Roderic A. Ellman

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. Foundation construction in the Potomac River required the use of cofferdams to allow structural concrete work to be performed in the dry. This paper will the present the types of cofferdams used to construct the foundations for the WWB replacement project. The bridge is primarily comprised of fixed spans in relatively shallow water and a bascule span over a navigation channel in relatively deep water. Foundation construction included the installation of 48" to 72" open end steel pipe piles and cast-in-place concrete pile caps. To achieve the desired bridge appearance, pile caps were required to extend below the water surface and below the existing river bottom in shallow water locations. Conventional steel sheet pile cofferdams with tremie concrete seal were used to construct fixed span, shallow water piers. Selection of deep water bascule span foundation cofferdams was governed by several factors including contraction scour, environmental considerations and cost. Potomac River cofferdams, i.e., relatively shallow depth cofferdams that are supported by the foundation piling were selected. This cofferdam system provided a shallow profile which minimized contraction scour and the amount of filling in the river. Design issues include load selection and cofferdam stability in very soft alluvial soils. Construction issues include erection sequence, tremie concrete mix design and placement procedures.

Jan 1, 2005

By Ambarish Ghosh, Subhaprasad Chakraborty

"Construction of basement floors has become necessary to meet the requirement of parking in office and residential complexes and in hospitals for radiotherapy treatment. Important projects coming up in Kolkata are mostly in closer proximity of residential buildings, office buildings and historical monuments. Sheet piling is mostly used as temporary shoring system during construction. Deep excavation in urban environment creates great problem related to construction induced vibration due to driving of sheet piles for basement, pile driving etc. which raises the chances of damage of adjacent buildings and nearby structures. Vibratory sheet-pile driving is the most common method of sheet pile installation. The knowledge of induced vibration due to this phenomenon is still very deficient. This paper presents the analysis of measured vibration data collected from different sites of Kolkata with varying soil profile. Typical two case studies of sheet pile and pile driving has been presented and the vibration values are analysed. The responses of the vibration are reported in terms of peak particle velocities (PPV). To evaluate the effects of vibration due to pile driving two aspects have been considered: the effect of the energy entering the ground from the pile and the effect of the soil condition.INTRODUCTIONIn urban areas infrastructure development projects are mainly located adjacent to existing structures like residential buildings, offices and historical structures. The construction work of such project influences the surrounding environment as well as human perception (Wiss 1981). During the construction of basement for residential complexes and hospitals sheet piling is mostly used as temporary shoring system or as to support the earth mass. The vibration induced due to driving of piles and sheet piles have been presented herein. Deep excavation projects close to existing structures increase the concern of environmental impact. For this reason the vibration assessment and prediction has become a subject of great interest. It is important to develop a site specific model for predicting the ground vibration resulting from pile and sheet pile driving at the construction sites. The developed model gives the efficacy to guide the engineer to select the construction methodology ensuring the safety of the surrounding structure. The model developed here is site specific and the parameters that has been used are dependent on the soil condition and the energy source."

Jan 1, 2015

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 N. V. Nayak

Konkan Railway Project is one of the most ambitious railway construction projects in India, involving construction of a 760.km long, Broad Gauge (1676 mm), single track railway line, connecting Roha in Maharashtra State with Mangalore in Kamataka State. The railway line travels along the Western Coast of Indian subcontinent, through states of Maharashtra (382 km), Goa (105 km) and Karnataka (273 km) (Fig.1). The project alignment traverses through one of the most formidable terrains ever encountered, in the history of railway construction in India. In the State of Goa only, railway alignment is crossing 6 major rivers Terekhol, Chapora, Mandovi, Zuari, Sal and Talpona. Zuari Railway Bridge (1305.6 m), Mandovi Railway Bridges (I and II) (1182.7 m) rank as 2nd and 3rd long bridges, (first longest bridge being Sharavati Bridge (2.2 km} at Honavar) which have been constructed on Konkan Railway. All these three bridges have been constructed by M/s.Asia Foundations and Constructions Ltd. (AFCONS). This paper presents, case history of construction of pile/caisson foundations for Zuari and Mandovi Bridges.

Jan 1, 1996

By Ehab S. Shatnawi

It is common in practice to design laterally loaded rock-socketed drilled shafts using the p-y curve methods. However, the existing p-y curve criteria for rock were derived either semi-empirically or based on the assumption that the rock is an elastic isotropic continuum. The assumption of isotropy may be invalid for rocks with intrinsic anisotropy or for rocks with joints and bedding planes. Therefore, there is a need to develop a new p-y curve criterion to take into account the effects of rock anisotropy on the response of laterally loaded shafts. This paper presents a method for estimating the initial tangent Ki to the p-y curve for rock that can be characterized as transversely isotropic elastic continuum. Examples of transversely isotropic rock formation can be seen in most sedimentary rock where dominant bedding planes exist. The knowledge of the initial tangent to p-y curve is important, because it controls to a large extent the predicted deflection of laterally loaded drilled shaft in rock. The 3-D finite element parametric study results of a laterally loaded drilled shafts socketed in transversely isotropic continuum are employed to develop a series of design charts for estimating Ki as a function of transversely isotropic elastic constants.

Jan 1, 2007

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 Hyung-Min Kwon

There are a number of methods available that can be used to estimate the bearing capacity of piles that are subject to lateral load, such as the theory of subgrade reaction or the elastic continuum approach. The objective of these approaches is to determine the lateral load corresponding to the allowable lateral displacement of the pile. It is important to select the appropriate soil stiffness when analyzing soil behavior within the allowable displacement of piles because the stiffness of soil is dependent on the displacement of piles. Even though pressuremeter tests can measure the stress-strain behavior within a wide strain range, pressuremeter test results have been utilized to assess only the fragmentary soil modulus based on either semi-empirical correlations or analytical approaches. This study is concerned with a methodology that can estimate the horizontal deformational property, while taking into consideration the nonlinear deformational characteristics of sandy soils. Pressuremeter tests were conducted for 15 cases using a calibration chamber. Reloading curves were employed in the estimation of horizontal deformational property in order to minimize the effect of soil disturbance caused by the installation of the probe. The shear modulus degradation characteristics were estimated from the curve fitting for the reloading curve and from extrapolation using the exponential function. In addition, the difference was taken into account between the stress state around the probe in reloading and that of the in-situ state. A consistent relationship was observed between the maximum shear modulus taken from the suggested method and the bender element tests performed in the calibration chamber, simultaneously with the pressuremeter tests. In addition, the results showed significant concurrence with the well-known empirical correlation.

Jan 1, 2008

By James C. Scott

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

Jan 1, 2007

By Colin Curtis

The City of Manchester is hosting the 2002 Commonwealth Games. A world class Stadium with a 38,000 capacity was commissioned for a site located close to the City Centre. The Stadium location is in an area that was derelict and in need of regeneration and it is envisaged that the Stadium will be the spur for this. The industrial and residential history of the site has left a legacy of buried foundations together with chemically contaminated soils. This Made Ground deposit overlies Glacial Deposits which in turn overlie bedrocks of the Central Manchester Coalfield. Coal mining has taken place from at least 1761 leaving several worked seams and shafts. In order to support the stadium, 1159 conventional augured piles of 600 to 1200mm diameters were used. This paper will deal primarily with the piling operations and testing, but will also discuss the coal seam treatment with respect to piling. A substantial trial pile test programme was carried out together with 11 static load tests on contract piles. The results of the pile tests will be discussed and conclusions drawn.

Jan 1, 2002

By Barry C. Roth

Driving of large piles in water can impact marine wildlife. Bubble curtains can mitigate these adverse effects. The procedures for and preliminary results of monitoring airborne, waterborne and groundborne vibrations with and without bubble curtains on a test project involving 2.438 m piles to 110 m is reported here. We observed fish kills and sea lions apparently fleeing the area. These phenomena were presumably due to the extreme acoustic effects of the powerful hammers which generated waterborne sound intensities locally in excess of 240 dB. This waterborne pile driving noise data collection undertaking is believed to be the most extensive ever attempted.

Jan 1, 2001

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shaft (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, including the post-grouting of all drilled shaft tips. ? Design and construction of the scour protection for the two main pylons, ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2013

By A. Partos

It was decided to build a fourteen-storied office building over a six-storied garage and a four-storied office building. The high vertical and horizontal loads required foundations on rock approximately 18m below street level. Drilled piers (caissons) were selected. Eight caissons (1.98m diameter) were installed through the six-storied garage and four caissons from a temporary deck at the location of a former two-storied building. Excavations were done by the slurry method. Proof testing of rock was done before construction by test borings and during construction with a core barrel of small diameter. Quality control measures included telecommunications between ground crews and the equipment operator on the garage roof; records of field observations and testing of bentonite slurry and rock; and a continuous evaluation of all information. Instruments were installed in one caisson to monitor load distributions and curing of concrete.

Jan 1, 2010

By Serge Borel

An efficient design method is proposed for "piled-footing" and "piled-raft" foundation under lateral loads. It combines the methods used for the displacement design of shallow and deep foundations and takes into account the interactions between the piles and the cap or raft. This method has been applied to previous full-scale tests carried out in the United States. Two groups of six instrumented driven piles were laterally loaded several times: first with the concrete pile cap in direct contact with the soil, and then, after a thin layer of soil had been removed beneath the cap. The proposed method models well the real behavior of piled-raft foundations. It highlights the positive effect of the cap in contact with the soil, which reduces significantly the displacements and the maximum pile bending moments. These are divided by two for the analyzed case histories.

Jan 1, 2002

By Helene Kennedy, Josef Macsik, Yvonne Rogbeck, Gregory Makusa, Göran Holm

"Constructions activities in cities often imply large volumes of surplus material which could be treated by stabilization for re-use in new geotechnical constructions. Modification of dredged sediments by e.g. stabilization/solidification (s/s) is an example of sustainable handling option implying dredged contaminated sediments to become a potential resource for civil engineering constructions. The SMOCS project (Sustainable Management of Contaminated Sediments) within the Baltic Sea Region Programme 2007-2013 has developed a guideline based on a sustainability approach free to download at www.smocs.eu. The paper presents key issues in the guideline and highlights the importance of performing a field test as part of the design process. Two field tests with s/s-treated dredged sediments for new port areas are presented. Strength, permeability and leakage properties of s/s-treated contaminated sediments make beneficial use in geo-constructions possible. The influence of possible physical/chemical deterioration processes on the durability has been studied showing that freeze/thaw cycles might degrade the monolith of s/s-treated sediments. Consequently s/s-constructions shall be below freezing depth. Other deterioration processes such as salt and sulfate penetration were found of minor importance. Research is on-going to study the influence of and how to cope with freeze/thaw cycles on the long-term properties.BACKGROUNDConstructions activities in cities often imply large volumes of surplus material which could be treated by stabilization for re-use in new geotechnical constructions. The mechanical and environmental properties of the contaminated sediments could be modified through the stabilization/solidification method (s/s method) and provide a potential resource for civil engineering constructions. The SMOCS project (Sustainable Management of Contaminated Sediments) within the Baltic Sea Region Programme 2007-2013 has developed a guideline on management of contaminated sediments based on a sustainability approach. A field test on the application of the stabilization/solidification method for treatment of dredged soft contaminated sediments was implemented in the Port of Gävle, Sweden. The treated sediments were beneficially used as fill material in the new port area replacing ending natural resources."

Jan 1, 2015

By C. Guney Olgun, Fleur Loveridge, Tracy Brettmann, William Powrie

"Abstract Deep foundations are increasingly being used, not just to carry structural loads, but also to act as heat exchangers as part of a ground source heat pump system. Such foundations, often called energy piles, have the potential to make significant contributions towards meeting the heating and cooling demands of buildings, thus reducing the overall energy consumption and carbon dioxide emissions during their lifespan. To ensure that the available energy from these systems is maximized, it is important to determine the thermal conductivity of the surrounding soils, a key design input parameter. In situ thermal response tests are commonly used to carry out this task for small diameter borehole heat exchangers. However, there has been debate over the applicability of these tests to energy piles due to their larger diameter and the consequent increased influence of the pile thermal properties on the test outcome. This paper examines the results of three thermal response tests carried out on piles of different diameters and thermal properties installed at the same site in Texas. Transient analysis of the test results, combined with comparisons to laboratory testing of soil samples from the site, is used to given an indication of the applicability of the thermal response test over different timescales for the different piles. It is concluded that the test is most suited to smaller diameter piles constructed with lower thermal diffusivity materials. Recommendations are given for the conduction of pile thermal response tests and interpretation of test data.INTRODUCTIONAs issues of energy security and scarcity become more important, the use of ground source heat pumps to provide renewable and sustainable heating and cooling to buildings is set to increase. Traditionally such systems use special purpose ground heat exchangers to extract and/or inject heat from/into the ground. The heat exchangers comprise a series of plastic pipes cast into the ground and then connected to the heat pump via a series of header pipes. In the case of building space heating, the heat pump then steps up the temperature difference to deliver the extracted heat at a useable level. However, financial and carbon savings can result by utilizing the building foundations as heat exchangers as well as to carry the building structural loads.Piles, often termed “energy piles”, are the most common type of foundation heat exchanger, and their construction has been increasing in recent years (Amis et al, 2009). However, while energy piles have the potential to make significant contributions towards meeting building heating and cooling demands, there remains scope for improving their thermal efficiency through improved analysis approaches (e.g. Loveridge & Powrie, 2013). In fact the greater diameter of many energy piles means they have the potential to deliver increased short term thermal energy storage compared to more commonly installed borehole heat exchangers."

Jan 1, 2014

By Carl Ealy

Static and STATNAMIC (STN) rapid load test (RLT) was performed on 3-drilled shafts. The purpose of the RLT part of the study was to obtain data in support of FHWA research on innovative load testing methods. The research site is located at the National Experimentation Research Site (NGES) in Amherst Massachusetts and is underlain by Connecticut valley varved clay. Two of the tested shafts were constructed without planned defects and the third with manufactured defects to evaluate current non-destructive integrity testing (NDE) methods. Quick Load Test (QLT) and Constant Rate of Penetration (CRP) static axial load tests were performed on two shafts to plunging failure. Good agreement between static and RLT derived static failure loads was attained for a 5% failure criterion (load at a movement equal to 5% of shaft diameter).

Jan 1, 2002

By Jason N. Scott

It is now possible using low-cost wireless technology and rugged hand-held devices to record data on site electronically and for that data to be instantly available to others. This could potentially eliminate many problems that traditionally lead to remedial work, such as poor communication and the late detection of non­conformances. However, determining how best to implement such a system and integrate it with the rest of the business process is far from simple. This paper looks at Stent's experience of these issues by way of a case study of the SHERPA system. This is a wireless site data collection system developed for use with rotary bored piling.

Jan 1, 2006

By Michel Bustamante

The original Cistercian Lure abbey situated in eastern France and built in the second half of the 16th century, has become nowadays an administrative building. Because it has been founded on poor ground conditions and inadequate foundation scheme, the abbey has suffered severe structural distortion. In 1992 an inspection revealed new extensive damages which led to a general refection together with a foundation underpinning. Micropiling was the selected method. Movements recorded over a period of 6 years after underpinning completion are presented.

Jan 1, 2002

By Terence P. Holman

Instrumented load testing of high capacity micropiles, followed by detailed analysis and numerical modeling, provided an opportunity for real foundation performance to be incorporated into the design of a complex urban high-rise structure. This paper discusses a design-based load testing program and subsequent analysis for micropiles incorporated into a piled raft foundation beneath a portion of a high-rise residential structure in Brooklyn, New York. Preliminary numerical analysis, performed using the commercial finite element package PLAXIS 3D Foundation, indicated that soil stiffening and transferring heavy core loads to greater depths was required to minimize the total and differential settlements. High capacity micropiles were modeled below the tower core mat to create a piled raft effect, reducing the settlements to acceptable levels. Final design of the foundation and micropiles, and final numerical analysis of the proposed foundation system required an instrumented load testing program to provide the Owner and design team with a level of comfort. The instrumented load test provided data on the evolution of load transfer, including the mobilization of significant tip resistance, frequently ignored in design, and micropile axial stiffness. Final numerical analysis of the foundation system involved refining the PLAXIS model based on the micropile behavior and load transfer mechanism observed during the load test program. The authors believe that the combination of design-based load testing and numerical analysis in this project yielded a more refined foundation system with realistic expectations of performance.

Jan 1, 2007