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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 Hennie F. T. Barnard

Where geotechnical designs are governed by settlement requirements, soil and rock moduli are important parameters for design. This paper reports on a method that was used to utilize dynamic modulus measurements in the field toward pile settlement designs for the proposed Square Kilometer Array (SKA) Project to be located near Carnarvon, South Africa. The project will comprise of over 3000 No. movement sensitive satellite dish structures. The method described in the paper utilizes strain-related modulus degradation across the complete ground profile, starting from measurements of peak particle velocity (and inference to dynamic modulus at small strain) as measured using Continuous Surface Wave (CSW) testing at individual dish positions. This is required due to the very small allowable foundation rotation of 5 arc seconds under the dishes? operational conditions. The strategy of analysis was to conduct an iterative process starting from the measured small strain modulus profile of the ground. The likely maximum pile force for a specific piled foundation option was estimated and a single pile finite element analysis was performed using Plaxis 2D (Version 2010) to estimate the expected ground strain developing along the length of the pile. By assuming the shape of the shear modulus degradation curve with increasing shear strain, the iteration process then converged on a likely degraded modulus profile associated with the single pile and maximum load assumed. This process enabled identifying the pile cap size, pile configuration, pile sizes and pile lengths that would meet the operational movement limits. The chosen pile group configuration was then analyzed using the Repute 1.5 pile group analysis software. The design process and typical results are discussed in this paper.

By Hennie F. T. Barnard, Theodore E. B. Vorster

Where geotechnical designs are governed by settlement requirements, soil and rock moduli are important parameters for design. This paper reports on a method that was used to utilize dynamic modulus measurements in the field toward pile settlement designs for the proposed Square Kilometer Array (SKA) Project to be located near Carnarvon, South Africa. The project will comprise of over 3000 No. movement sensitive satellite dish structures. The method described in the paper utilizes strain-related modulus degradation across the complete ground profile, starting from measurements of peak particle velocity (and inference to dynamic modulus at small strain) as measured using Continuous Surface Wave (CSW) testing at individual dish positions. This is required due to the very small allowable foundation rotation of 5 arc seconds under the dishes’ operational conditions. The strategy of analysis was to conduct an iterative process starting from the measured small strain modulus profile of the ground. The likely maximum pile force for a specific piled foundation option was estimated and a single pile finite element analysis was performed using Plaxis 2D (Version 2010) to estimate the expected ground strain developing along the length of the pile. By assuming the shape of the shear modulus degradation curve with increasing shear strain, the iteration process then converged on a likely degraded modulus profile associated with the single pile and maximum load assumed. This process enabled identifying the pile cap size, pile configuration, pile sizes and pile lengths that would meet the operational movement limits. The chosen pile group configuration was then analyzed using the Repute 1.5 pile group analysis software. The design process and typical results are discussed in this paper.

Jan 1, 2017

By Tim Siegel, III Fondren, Billy Camp

"INTRODUCTIONThe new $650 million power block at Santee Cooper’s Cross Generating Station in Cross, South Carolina is being constructed on driven pre-stressed concrete (PSC) piles. S&ME, as geotechnical subconsultant to Parsons Energy and Chemical Group, was responsible for pile analysis and design to meet the site’s geotechnical and seismic challenges. Selection, analysis and design of the PSC piles included consideration of the following:• Column and equipment support loads ranging up to 500 to 1000 kips (2224 to 4448 kN).• Incorporation of the 2000 International Building Code seismic provisions.• A thick upper soft clay and loose, liquefiable sand.• Potential for karst-related features in the calcareous Santee Limestone.GEOTECHNICAL CHARACTERIZATIONThe near-surface site geology consists of (in order of increasing depth): (1) Pleistocene sediments, (2) the Santee Limestone (considered part of the Orangeburg Group) of Eocene age, and (3) the Black Mingo Formation of the Eocene/Paleocene age (refer to the shear-wave profile in Figure 4). Pleistocene clays and silts are generally soft and will settle significantly if subjected to loading by heavy grade-supported structures while the interbedded sands are generally loose. Where submerged below the shallow groundwater table, the sands were determined to be liquefiable during a strong earthquake.The Santee Limestone is a nearly white to yellow fossiliferous and partly glauconitic rock consisting chiefly of calcium carbonate. Observations of the rock core samples from the site indicate that it can range from hard crystalline limestone (primarily in thin layers) to a lightly cemented sand. In terms of rock strength, the Santee Limestone is generally very soft to soft, depending on the cementation and other depositional characteristics."

Jan 1, 2004

Volume 1 pages 665-671 Title should read as Dynamic pile testing of H-piles at HDB sites J.Wei, Y. S. Heng, C. S. Lok, M. K.Chong Housing and Development Board, Singapore 'tons' should read as 'tonnes' Para 3.2 fourth equation (page 667) [TC = t2 v.dt t = 0 should read as TC = t2 v.dt - s t = 0]

Jan 1, 1994

By Yoshinori Kurumada, Tatsuo Nagatsu, Keiji Uchida

"Cement deep mixing method has been utilized in the process of construction of an underwater tunnel in Singapore. The soil was improved by this method to prevent undesirable heaving of the soil below the excavated area. Quality control experiments approved the effectiveness of CDM method in increasing the strength of the soil and prevention of undesired heave of the ground. The process of the construction of this project and the quality control experiments results are discussed in this paper.INTRODUCTIONThe Marina Coastal Expressway is a 5.3 km long underwater highway tunnel with five lanes in each direction. It mostly comprises a twin box culvert structure (53.3 m exterior width and 10.89 m height) and was opened by the Land Transport Authority of Singapore (LTA).The contract zone C485 was the most challenging area of the construction; it involved a 700 m long underwater tunnel of which 400 m was built beneath the seabed at the mouth of the Singapore River. A double steel pipe sheet pile wall was built as a temporary cofferdam to keep water out of the excavation site, and the cut-and-cover method was used for excavation. In order to ensure a sufficient cross-sectional area for the flow of the Singapore River, the construction was divided into two phases focused on the left bank (Stage 1) and right bank (Stage 2).The Cement Deep Mixing (CDM) method was used to improve the ground, which comprised soft marine clay, to ensure safety during the excavation. The efficiency of this method in increasing the soil’s strength was approved previously. The design standard strength was quck = 800 kPa. Based on the study conducted after the construction, the average the Unconfined Compression Strength (UCS) of the soil stabilized by the CDM method was quf =3,000 kPa. This paper discusses the effect of the CDM soil improvement construction on the reduced displacement from the excavation and the quality control of the soil improvement."

Jan 1, 2015

By Wayne S. Smith, Erik James, Jose R. Gomez

"Soil mixed seepage cutoff walls are increasingly being used in levee and dam modification projects nationwide. An important aspect of their overall quality depends greatly on the language included in the specifications. Depending on the method (e.g. vertical axis auger mixing, cutter soil mixing, or trench mixing techniques) the specifications are a blend of prescriptive and performance based contract language with differences in element construction, element connections, quality control/quality assurance, and work area restrictions. Many of the existing specifications were initially developed by contractors in whole or in part, and can contain restrictive provisions favoring the authoring contractor. In response to these challenges, basic soil mixing fundamentals were revisited and recent lessons learned incorporated, resulting in the development of a new specification for soil mixed seepage cutoff walls that provides adaptability for the various construction methods. The new specification addresses quality control, quality assurance, equipment independence (elimination of restrictive contract language), rig instrumentation.INTRODUCTIONSoil mixing has been used in the construction of seepage barriers for over 30 years. Most soil mixed project primarily use the wet-rotary-shaft, wet-rotary-end or wet-vertical panel methods (reference FHWA Deem Mixing Manual Figure 137). One of the first major soil mixing seepage barriers was constructed in the Jackson Dam in Wyoming. Since then the use of soil mixing for seepage barriers has increased significantly and this specialized domain of construction which was solely procured by RFP methods, is now increasingly being specified in projects issued for bid. The Bid documents require more careful specification writing than RFP methods because the RFP methods allowed detailed proposals by the contractor. Therefore the development of soil mixing specifications began with contractors preparing the specifications. This paper addressed some of these issues, and proposes methods to address these resulting concerns. The resolution of these issues considers several aspects: 1) Assessment of binder injection, 2) Evaluation of mixing index, and 3) Verification testing."

Jan 1, 2016

By W. Morgan NeSmith

"The DFI ACIP Pile Committee, in conjunction with the Florida DOT, completed an ACIP Pile installation monitoring and performance test program in late 2016 to advance the inclusion of ACIP piles in future specifications for bridges by state agencies. Piles of different diameters were installed for compression, tension and lateral testing, and one pile was extracted for visual inspection. This paper presents the pile installation, non-destructive testing and load test results of the program.INTRODUCTION The Deep Foundations Institute (DFI) Augered Cast-In-Place (ACIP) Pile Committee performed a ACIP pile installation and test program in the fall of 2016 to demonstrate a fully monitored installation of 18-in and 24-in diameter ACIP piles. The program included automated and manual installation monitoring, Thermal Integrity Profiling, compression, tension and lateral load testing (including monitoring of strain gages embedded along the compression pile shaft), and post-testing extraction of an installed pile for visual inspection.PROJECT DETAILS AND FIELD EXPLORATION A general program location map along with an aerial view of the property in Okahumpka FL is shown in Figure 1. Two Cone Penetration Tests (CPT) were performed at initial reaction pile locations R-6 and R-8 (Figures 2 and 3) The results from CPT R-6 indicated very loose soil conditions at depths below 55-ft, indicating potential relic sinkhole conditions. The test layout was subsequently rotated and moved south of CPT R-8.TEST PILE INSTALLATION DETAILS Seven piles were installed to either 40-ft or 60-ft below grade. Thermal Integrity Profile (TIP) wires were installed in all piles but varied to include one wire each attached to a steel center bar or one wire attached to the steel center bar AND four additional wires (each) attached the steel reinforcing cage installed in these piles. Additionally, the 24-in lateral and compression piles had four steel or PVC casings installed next to the TIP wires for testing by thermal probe and/or wire inserted into the casing."

Jan 1, 2017

By Arash Khosravifar

One of our research thrusts at Portland State University (PSU) centers on developing design guidelines for pile foundations in liquefiable, laterally spreading grounds. This research has been primarily sponsored by the DFI Committee Project Fund (CPF) program through four awards, totaling nearly $240,000 in financial support. DFI contributed half of this financial support, while the other half was contributed in-kind by PSU and DFI Project Advisory Board members. Leveraging the CPF funds, we secured an additional $550,000 in financial support from the National Science. Foundation (NSF), which has enabled our research group to continue exploring this topic and contributing to the broader engineering community's understanding of the behavior of pile foundations in liquefiable soils. The CPF funds have fostered collaborations with practitioners and researchers beyond PSU. Notable examples include collaborative research involving data from five large-scale centrifuge tests on pile-supported wharves by Steve Dickenson, Ph.D., New Albion Geotechnical; Nason McCullough, Ph.D., Jacobs Engineering and Scott Schlechter, Geotechnical Resources, as well as 1-g shake table tests of bridge pile shafts conducted by Professors Ahmed Elgamal, Ph.D., and Ahmed Ebeido, Ph.D., of the University of California, San Diego. In addition to these collaborations, our research has benefited from industry-university partnerships formed through the involvement of DFI Project Advisory Board members. Their support and feedback ensure that our research products are practical and imple- mentable in real-world projects. The impact of the CPF funds extends to supporting graduate students' theses, which were the basis for 17 technical publications. Some of these publications are expected to have a significant impact on the industry. For instance, our 2018 DFI Journal paper, co-authored by former master's student Jonathan Nasr, cur- rently with the Army Corps of Engineers, has been cited in the 2022 British Columbia Supplement to Canadian Highway Bridge Design Code S6:19. A noteworthy product of our study is a step-by-step design procedure for pile- supported wharf structures subjected to the combined effects of lateral spreading and inertial loads, outlined in a 2022 American Society of Civil Engineers' (ASCE) Journal of Geotechnical and Geo- environmental Engineering paper co- authored by former doctoral student Milad Souri, Ph.D., PE, Geotechnical Resources.

Nov 1, 2023

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 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 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 Alan Christopherson

Nearshore construction projects often require installation of steel piles and specific methodologies of installing piles may adversely affect nearby species of concern. Water is an uncompressible medium which allows for easy transmission of energy through the water column. Energy transmission through water depends on the following factors for pile driving: 1) direct contact of the pile and the water; 2) the depth of the water column; 3) the size of the pile; 4) type of hammer; and 5) the energy of the hammer. Seasonal restrictions are usually the best practicable alternative for reducing habitat impacts when pile driving activities may adversely affect the species of concern. When seasonal restrictions are not practical other options need to be evaluated, including mitigation and noise attenuation devices. The broad array of mitigation options will not be discussed as part of this presentation but instead will focus on noise attenuation technologies. Dewatered cofferdams can be effective noise attenuators as they eliminate direct contact of the pile with water while driving. Also, introduction of a compressible medium, like air, near the energy source can provide sound energy attenuation. An unconfined bubble curtain is relatively inexpensive but is not effective in tidal marine projects or rivers and may have unacceptable secondary effects. Secondary effects must be evaluated as these can increase exponentially for larger projects. Secondary effects to the environment include air quality degradation from air compressor use, transportation costs for fuel and equipment, and the potential for injecting oily compressed air into the water column. The confined bubble curtain works well in nearly all environments. It usually is more expensive initially, relative to an unconfined air curtain, but there is less potential for harmful secondary effects. Generally, seasonal restrictions will be adequate to protect species of concern. However, there are conditions in which mitigation or one of the sound attenuation options should be utilized. Site specific factors, including the amount of energy being imparted into the environment, sensitivity of the species of concern, current, accessibility, length of time needed to complete the project, and the cost of the sound attenuation, should be factored into the permit evaluation.

Jan 1, 2013

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 Jesus Gomez, Mary Nodine

Rigid inclusions are widely used in the U.S. as a ground improvement tech- nique, particularly for industrial, low- rise and highway applications with poor subsurface conditions, where control of settlement is necessary. Rigid inclu- sions consist of grouted or concrete elements typically 12-24 in (305-610 mm) in diameter that may or may not be reinforced with a center bar. Typical soil conditions where rigid inclusions are feasible might consist of a surface layer of fill and natural, granular soil, followed by a stratum of soft silt or clay overlying a dense or stiff formation. Rigid inclusions are installed from the existing ground surface or suitable work platform, through the surface soils and through the soft, compressible layer, and into the deeper layer, which is less susceptible to compression- induced settlement. Typically, when used to support an extended area surcharge, the inclusions are installed in a rectangular or triangular pattern at regular spacings ranging from 5-12 ft (1.54 m), depending on a variety of factors. The rigid inclusion system is often capped with a load transfer platform (LTP), whose function is to direct a significant portion of the applied load toward the rigid inclu- sions. Additional load is transferred to the rigid inclusions through the upper fill soils above the compressible layer. The rigid inclusions transfer the applied load axially to their tips and into the deeper layer. In the U.S., rigid inclusions are mostly installed using displacement auger systems. The use of a dis- placement auger has significant advantages. It produces zero to near- zero spoils, which is an important environmental consideration. The

May 1, 2023

By Peter Faust

"The south access road to San Francisco’s Golden Gate Bridge, known as Doyle Drive or Presidio Parkway, needs to be replaced. Built in 1936, it is the primary highway and transit linkage through San Francisco between counties to the north and south. The roadway is tucked into the natural contours of the Presidio and the Golden Gate National Recreation Area, one of the nation’s largest urban parks.The old steel truss structure will be replaced by a new concrete cast-in-place bridge. The foundation design of the new bridge is based on drilled mono shafts below each bridge column. Most shafts required large diameter permanent steel casing installed under strict vibration limitations since several historic landmarks are near the project alignment. Malcolm Drilling decided to use the largest oscillator in the world to install the piles.The area occupied by the Presidio is generally hilly, sloping down northwards to San Francisco Bay. In the western half of the project route, two bluffs rise steeply to about 80 ft (25 m). The bluffs are separated by a valley 60 ft (18 m) deep and 1,500 ft (457 m) wide, which is spanned by the old and new bridge. Overburden soils in this valley are made up of artificial fill, slope debris, ravine fill and Colma Formation, a fine to medium-grained sand unit with clay beds. The Bay Muds encountered in the project area are typically soft clayey silts, becoming medium stiff with depth.The basement rocks underlying the overburden belong to the Franciscan Formation, described as shale, sandstone, serpentine and greywacke, it is extremely variable in hardness, fracturing and weathering. The material can vary from very hard to very soft, can be slightly to very intensely fractured and almost not weathered, to totally decomposed within relatively short distances both laterally and vertically. Rock strength can vary from too weak to be tested to serpentine layers with unconfined compressive strength of 15,000 psi (103MPa) or higher. Groundwater levels in the area are typically no more than 10 to 20 ft (3 to 6 m) below the ground surface."

Jan 1, 2012

By Narong Thasnanipan

Performance of diameter 1.5 m toe-grouted bored pile founded at depth 44 m in sand-gravel formation of Chiang Mai City is presented in this paper. Toe grouting was applied by using tube-a-manchette method. Effectiveness of toe grouting was observed from the standard penetration tests conducted immediately below pile toe through grouting pipes at two stages, prior to grouting and three weeks after completion of grouting. Improvement of pile end resistance by toe-grouting is demonstrated with a series of back analyses carried out by load-transfer method employing hyperbolic transfer function. Construction experience of large diameter deep-seated bored piles in multi-layered subsoil and practical aspects of toe-grouting are also briefly discussed.

Jan 1, 2002

By Prakash Annamalai Rangasamy, Muthukkumaran Kasinathan

"Infrastructure development like elevated expressways, metro train and flyover are required proper foundation system to carry heavy traffic loads/significant lateral load, especially in the presence of hard stratum at shallow depth. Pile foundation under bridge pier system is widely adopted in metro projects where the piles are essentially socketed in rock. However, the drilling in hard rock is a time consuming process and needs heavy machineries which lead to delay in construction activities. In the present study, the influence of free standing height on rock socketing under lateral load is investigated. The experiments were conducted on an instrumented model pile with varying depth of socketing and for varying Lf/D ratios. The experimental results shows the load carrying capacity of the pile increases by increase in Lf/D ratio, where in the case pile without socketing (bearing on rock) is compared with 3D depth of socketing. Thus socketing the pile provides significant benefits on carrying capacity of lateral loads. Embedding the pile into hard strata reduces the lateral displacements substantially compared with pile bearing over hard strata. Form the study, it is noticed that the influence of rock socketing has significant effect in the lateral load capacity. And also, the effect of free sanding height play a major role in the lateral load capacity of the rock socketed piles.1. INTRODUCTIONA substructure carrying heavy lateral load at shallow depth, the structure has to be socketed into hard strata to enhance the efficiency of load carrying capacity. The existing field practice is to socket the end bearing piles in hard strata over a minimum depth of four times the diameter of the pile based on rock classification (IS 14593:1998). Reese (1997) developed p-y curves for analysing drilled shafts in rock under lateral loading, based on strong and weak rock criteria. The proposed p-y curve approach has the ability to simulate the nonlinearity and non-homogeneity of the rock mass surrounding the drilled shaft. Gabr et al. (2002) proposed a hyperbolic p-y criterion based on field tests on small diameter drilled socketed shafts. By considering pile as linearly elastic semi-infinite space and soil as homogeneous isotropic material, Poulos (1971) proposed solution to determine the horizontal displacement and pile head rotation. Poulos (1972) extended this elastic continuum approach to give an approximate solution by considering drilled shaft and pile bearing on rock as fixed and pinned end boundary condition. Zhang et al. (2000) developed a non-linear continuum approach for drilled shafts in a soil and rock mass by considering the effect of soil and/or rock mass yielding on the behaviour of shafts. Randolph (1981) conducted a parametric study on the response of laterally loaded piles embedded in an elastic soil continuum. The study was conducted using the finite element method and the results were fitted with closed-form expressions from which the lateral responses of piles were calculated. The solutions given by Randolph (1981) were expanded by Carter and Kulhawy (1992) from the results of finite element studies on the behaviour of laterally loaded flexible and rigid drilled shafts in rock. Desai and Christian (1977) gave a finite difference program to solve rock socketed problems by considering soil and rock mass as elastic-perfectly plastic. Zhang et al. (2000) verified the proposed finite difference method with existing field test results. Gabr et al. (2002) and Liang and Yang (2006) proposed hyperbolic p-y curves based on filed test results and verified with finite element programs. However the need of field and lab scale experimental studies to validate the existing methods of analysis is necessary."

Jan 1, 2015

By John G. DiGenova

The Allwell Center Ice Arena at Plymouth State University, Plymouth, New Hampshire is located in the flood plain of the Pemigewasset River. To maintain the arena near the level of the surrounding area, foundation design required use of uplift elements to resist hydrostatic loads caused by frequent flood conditions. Soils beneath the arena consisted of very loose to medium dense alluvial deposits overlying thick glaciolacustrine deposits. Bedrock was encountered at depths of 115 feet (35 m) or more. A mat foundation with a sealed building system was developed for the arena to guard against flood events. Several alternatives were investigated to provide uplift capacity for the mat foundation, including the Rammed Aggregate Pier® (RAP) system, driven precast-prestressed concrete piles, driven H-piles, and deep drilled soil/rock anchors. Evaluations indicated that the most cost effective uplift solution was a tension RAP system that developed uplift resistance in the shallow alluvial deposits. A total of 344 55-kip (245-kN) capacity RAP elements were required for the project. The RAPs were designed to resist tensile loads using threaded steel bars. Dual corrosion resistance was provided to the uplift elements by including sacrificial steel and galvanizing the oversized bars and connection plates. A pre-construction test program was conducted on RAP elements drilled to a depth of approximately 25 feet (7.6 m) and installed using various shaft construction procedures and materials. Ten test piers were constructed and six were tested to verify that the piers could resist 200 percent of the design load with measured deflections of less than 1 inch (25 mm). The RAP system also provided improved bearing conditions for the perimeter wall and mat foundations by densifying and stiffening the upper alluvial soils.

Jan 1, 2011