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By John P. Briand III, Douglas J. Aghjayan, Robert E. Fosse

This paper highlights the successful pile load testing program for the redevelopment of Pier One in East Boston, Massachusetts. Pier One is a 5.4-acre parcel on a dormant waterfront site used in the 1950s as a warehouse and distribution facility. The developer plans to re-use the existing 14-inch-diameter concrete-filled steel pipe piles to support four 5- to 7-story apartment buildings above a 2-story parking garage. A pile load testing program was developed to establish if the existing piles could support design loads of 240 kips for project financial feasibility and up to 300 kips for a significant reduction in future foundation costs. The Phase 1 program consisted of statnamic and dynamic load testing on two piles with two loading intervals (200 and 240 kips). Based upon the favorable results of the Phase 1 program, the Phase 2 program involved statnamic load testing on two piles and dynamic load testing on ten piles with three loading intervals (200, 240, and 300 kips). The Phase 2 program confirmed the favorable results which were applied across varying strata thicknesses and pile embedment depths. The average allowable capacity for the piles tested was greater than 300 kips with pile movement up to 0.3 inches.

By David M. Rempe

The purpose of this standard is to provide a method for testing of cushion materials that leads to uniform results when employed by various organizations and laboratories. The load-deflection characteristics measured using this method are intended to provide input data for analysis of pile driving, as in wave equation analysis of pile driving. It should be recognized, however, that there are several factors which may cause a difference in performance between the test samples under laboratory conditions and actual cushion materials under pile driving conditions. These factors include variations in material properties from sample to sample, compaction and/or deterioration of the materials with use, eccentric loading due to misalignment, confinement effects or the cushion container or inter layered materials, head buildup, rate of loading, etc. In order to obtain representative load-deflection characteristics, therefore, testing of cushion specimens which have been subjected to actual pile driving conditions is encouraged 1 such specimen should be tested at various stages of the useful life of the cushion. The users of the data are cautioned to determine if the particular wave equation program they are using requires either the secant or tangent definition of the stiffness and modulus of elasticity.

Dec 1, 1984

By Helen S. W. Chow, Harry G. Poulos

Most modern buildings involve the construction of a basement, often of several levels, to maximize the floor area ratio. The basement walls are generally designed for excavation retention purposes only, and are infrequently considered as elements which can help to support the structural loads from the superstructure. However, the basement walls can provide substantial stiffness and resistance to structural loads, and may contribute to the overall foundation capacity and stiffness. This paper presents a simplified approach to approximate the overall foundation capacity and stiffness considering the various components of the foundation system, including the foundation piles, the basement floor slab, the basement walls and interaction between each foundation component. The effect of the basement walls in enhancing the foundation stiffness values is examined by reference to the results of finite element analyses which consider a foundation subjected to vertical, horizontal and moment loadings. The approximate approach is found to give results that are adequate for a preliminary assessment of the effects of basement walls on the overall foundation response, without the need for detailed three-dimensional finite element analyses.

Nov 1, 2022

"The Metropolitan St. Louis Sewer District (MSD) in Missouri, the country’s fourth largest sewer system, is upgrading its storm and wastewater infrastructure in a 23-yearlong, $4.7 billion initiative called “Project Clear.” Historically, during times of intense precipitation, the current sewer system becomes overwhelmed. The primary goals of this project are to improve water quality and to alleviate many wastewater concerns in the St. Louis region by planning, designing and building community rainscaping, system improvements and an ambitious program of maintenance and repair.Part of the system renovation has focused on constructing underground tunnels for storm water storage, permitting controlled drainage of runoff, and preventing overflows into rivers and streams. Construction plans for these storage tunnels called for eight vertical intake and ventilation shafts to be bored from the ground surface. These shafts will then be intercepted in the bedrock at a depth of about 150 ft (45.7 m) during the excavation of the 3,000 ft (915 m) long underground tunnel that will be about 28 ft (8.5 m) in diameter. According to John Deeken , a geotechnical engineer with Black & Veatch Corp. and construction manager for the Maline Creek project, the drilling and blasting technique for creating the shafts was ruled out because the project was located in a residential neighborhood. “We could have used rock coring or a cutter head, but the drop shaft for this project is constructed within 10 ft (3.05 m) of an existing 108 in (274 cm) diameter sewer main,” Deeken said. “We had to take precautions to avoid damage to it.”A primary planning mandate of all MSD Project Clear phases requires minimized impact on traffic and residents. The canister drilling method enabled work to be confined to the median of a residential boulevard running perpendicular to the side street without detouring traffic. In addition, canister drilling offered a highly-precise means to create the shafts, leaving a smooth-sided borehole, right on target. Ground conditions in this 132 in (3.35 m) diameter intake shaft were wet due to the high groundwater levels and close proximity to the Mississippi River. “They’ve been finding shale in 2 to 6 ft (0.6 to 1.8 m) layers between weathered layers of Mississippian limestone,” said Dan Spiecher, technician at Center Rock (CRI). “The 2 ft (0.6 m) layers we can punch through. The 6 ft (1.8 m) layers slow us down.”"

Jan 1, 2017

By Monica R. Garcia, Antonio Alberto S. Correia, Paulo J. Venda Oliveira

"The aim of this paper is to analyze the creep behavior of a Portuguese soft soil stabilized with binders in one-dimensional conditions, based on oedometer creep tests. The study focuses on the analysis of the effect of the binder content and binder type on the creep behavior of a stabilized soil. The results show that the best binder type for this soil, in terms of creep behavior, is composed of Portland cement and fly ash with a dry weight proportion of 75/25, as this promotes the development of secondary pozzolanic reactions. The results also show the decrease in the secondary compression index with the increment of the binder content, since it promotes an increase in the cementation bonds between soil particles. The general analysis of the results shows a clear dependence on C??and qu, until values of qu of 1500 kPa; after that this relationship is negligible.INTRODUCTIONThe geotechnical structures (such as embankments, dams and buildings) built on organic soils exhibit notable creep deformations, which increase the maintenance and exploitation costs and can even compromise their functioning. To attenuate the creep effects of the soft ground, some improvement techniques are frequently used, such as preloading or reinforcing the soil foundations with vertical rigid inclusions, like concrete piles, stone columns or deep mixing columns (DMCs). However, the installation of DMCs in the soft ground induces (via the arching effect) a transfer of stresses from the soft soil to the DMCs, which causes an increase in the creep settlement on the DMCs (Venda Oliveira et al. 2011).Notwithstanding the fact that the creep behavior of clays has been the object of several studies (Leroueil et al. 1985; Mesri and Castro 1987; among others), the study of the creep behavior of soil-binder admixtures has been practically ignored by the scientific community. The few studies on this theme have revealed that a stabilized soil’s creep behavior is dependent on: the type of binder (Venda Oliveira et al. 2013), the binder content (Correia 2011; Bobet et al. 2011; and Venda Oliveira et al. 2013), the stress level applied during the creep phase (Venda Oliveira et al. 2013), the organic matter content of the natural soil (Venda Oliveira et al. 2012; 2014), and the curing conditions (humidity, vertical stress applied during curing, and curing time) (Correia 2011; Venda Oliveira et al. 2012).The aim of this paper is to contribute to a better understanding of the creep behavior of a soil-binder admixture, by examining the results of oedometer creep tests. The study focuses on the analysis of the effect of the binder content and binder type on the creep behavior of a stabilized soil. Additionally, the creep behavior is correlated with the effective vertical yield stress and the unconfined compressive strength (UCS)."

Jan 1, 2015

By Craig H. Olson

"A new ship dock at a Philadelphia area refinery will be capable of docking the largest tanker to travel the Delaware River, the Stena V-MAX, which will induce significant lateral loads. The loads at the dock, a system of mooring dolphins and platforms, will be resisted by over 150 pipe piles, including some 20- and 30-in diameter, reinforced, concrete-filled pipe piles and H-piles. Construction included driving the pipe piles to the required ultimate capacity, flushing the pipe pile casing clean of overburden materials, followed by drilling rock sockets into the underlying Wissahickon Formation. The Wissahickon Formation is a complex subsurface that includes variations in depth to bedrock, rock quality, degree of weathering and the presence of very hard quartzite lenses or inclusions. Because of the problematic subsurface, the designers and client requested extensive pile dynamic analysis (PDA) testing by TRC Engineers (TRC).Before beginning, the contractor requested that TRC perform the WEAP (wave equation analysis program) to evaluate the proposed hammer (APE D30-32 open-end diesel) to drive the piles into the proposed bearing strata while maintaining allowable compression stress levels. The WEAP provided a prediction of blow counts and stresses for various ultimate capacities, and showed that for the HP14x89 piles with a required ultimate capacity of 480 kips, a blow count of at least four blows per in at a stroke of 8.0 ft was necessary.New Approachway RampThe PDA testing began at the new dock approachway ramp, parallel to the existing one. The new structure is a 300-ft-long by 21- ft-wide concrete deck supported on seven bents; each has two 24- ft-diameter steel open-ended pipe piles. Every pipe received an HP 14 x 89 x 80-ft pile that was later driven beyond the pipe pile tip to create a composite pile. The pipe piles were later cleaned of overburden materials and finally filled with concrete and rebar. At each bent, a cap was installed on top of each pair of pipe piles, and then a prefabricated concrete deck was added."

Jan 1, 2008

By Craig H. Olson

"Anew ship dock at a Philadelphia area refinery will be capable of docking the largest tanker to travel the Delaware River, the Stena V-MAX, which will induce significant lateral loads. The loads at the dock, a system of mooring dolphins and platforms, will be resisted by over 150 pipe piles, including some 20- and 30-in diameter, reinforced, concrete-filled pipe piles and H-piles. Construction included driving the pipe piles to the required ultimate capacity, flushing the pipe pile casing clean of overburden materials, followed by drilling rock sockets into the underlying Wissahickon Formation. The Wissahickon Formation is a complex subsurface that includes variations in depth to bedrock, rock quality, degree of weathering and the presence of very hard quartzite lenses or inclusions. Because of the problematic subsurface, the designers and client requested extensive pile dynamic analysis (PDA) testing by TRC Engineers (TRC).Before beginning, the contractor requested that TRC perform the WEAP (wave equation analysis program) to evaluate the proposed hammer (APE D30-32 open-end diesel) to drive the piles into the proposed bearing strata while maintaining allowable compression stress levels. The WEAP provided a prediction of blow counts and stresses for various ultimate capacities, and showed that for the HP14x89 piles with a required ultimate capacity of 480 kips, a blow count of at least four blows per in at a stroke of 8.0 ft was necessary. New Approachway RampThe PDA testing began at the new dock approach way ramp, parallel to the existing one. The new structure is a 300-ft-long by 21- ft-wide concrete deck supported on seven bents; each has two 24- ft-diameter steel open-ended pipe piles. Every pipe received an HP 14 x 89 x 80-ft pile that was later driven beyond the pipe pile tip to create a composite pile. The pipe piles were later cleaned of overburden materials and finally filled with concrete and rebar. At each bent, a cap was installed on top of each pair of pipe piles, and then a prefabricated concrete deck was added."

Jan 1, 2008

By George Piscsalko

"Quality control of drilled shafts and ACIP piles is greatly dependent upon the practices of the site personnel. In many applications it is difficult to properly inspect the shaft prior to concreting, such as when the shaft is drilled under slurry. In other cases, such as ACIP piles, it is impossible to inspect the shaft in any manner prior to concreting. There are numerous methods currently available to assess the integrity of drilled shafts and ACIP piles. Each method has its advantages and limitations. This paper will compare the various available methods as well as introduce a new method for assessing integrity in drilled shafts and ACIP piles. This new method, known as Thermal Integrity Profiling, determines the integrity over 100% of the shaft both inside and outside the reinforcing cage by measuring the hydration temperature of the concrete along the length of the shaft. These temperature measurements can be made by either passing a thermal probe through a standard Cross Hole access tube typically 12 to 48 hours after concrete placement, or from embedding thermal wires within the shaft prior to concrete placement and monitoring them with unattended data collectors for 12 to 48 hours after concrete placement. This Thermal Integrity Profile method will be described in detail and several case histories will be presented. Additional testing methods which will be compared include low strain Pile Integrity Testing, and Cross Hole Sonic Logging. Advantages and limitations for each method will be discussed.IntroductionDrilled shafts and Augered Cast-in-Place (ACIP) piles have been increasingly used over the past several years due to several reasons including the reduced noise and vibration, speed of installation for ACIP piles, and the large axial and lateral capacities which are attainable for very large drilled shafts. ACIP piles are drilled and cast without any visual inspection. Drilled shafts can be cast in a dry hole which allows for inspection of the hole prior to casting, but the casting process is very difficult to nearly impossible to inspect with any accuracy. Drilled shafts are frequently cast under slurry as a means to stabilize the surrounding soils during the construction process. When casting a drilled shaft under slurry, it is very difficult to accurately inspect the hole prior to casting and it is equally difficult to inspect the shaft during the casting process. Many of the above mentioned processes are blind to inspection and therefore the chances increase for having defects present in the completed elements."

Jan 1, 2017

By Paola Campana, Maurizio Lenzi

"In the paper a non linear model for the analysis of the pile response to the axial loads is presented. The study aims to find a general analytical solution concerning the pile-soil interaction modeled by means of the method of the load transfer curves. It makes use of a criterion based on the plastic and on the hardening work locally done by the shear stresses and due to the current elastic shortening of the shaft. Then a specific solution, denoted fractal model, is found applying recurrent relations that link the shaft shear stresses and the tip normal stresses to the pile settlements. These relations are based on that one proposed by Kondner in modeling the soil samples response in the triaxial tests and then used by Chin in the inverse slope method in estimating the pile capacity by the load test results. The comparison between the model predictions and the load tests measures validate the fractal model.INTRODUCTIONThe behavior of the axially loaded piles is known to be characterized by a highly non linear trend caused by the onset of plastic and irreversible deformations in the soil starting just from the first load levels. With the purpose to reach a deeper understanding of the pile-soil interaction, the influence of the soil inelastic properties on the distribution of the axial loads and of the vertical displacements is investigated. The research starts analyzing the behavior of an infinitesimal length of a pile embedded in a non linear homogeneous soil. That initial study leads to a criterion based on the plastic and on the hardening work locally done by the shear stresses and that allows to find the axial loads as a function of the elastic shortenings of the shaft. The relation that links the pile axial load to the elastic strain of the pile material is then used. That allows to find the vertical displacements and the axial loads as function of the depth in a parametric form in which the tip settlement acts as an independent parameter. The method of the load transfer curves is used and the effects of the pile technology are included in the soil constitutive relations. The analysis is then extended to the non-homogenous soils in a very effective way. The solution is applied taking as constitutive relations of the pile-soil interface the one proposed by Kondner to analyze the soil triaxial tests and by Chin to interpolate the pile response measured in the load tests."

Jan 1, 2017

By Michael E. Ameel

The vibrated beam method of installing a vertical barrier wall is one of the least applied techniques, yet given certain site conditions and constraints, it is a cost-effective and proven method of controlling lateral groundwater flows. A recent full-scale application of this technique demonstrated its usefulness at an active manufacturing facility located in Northern Wisconsin. At this site, a 3,233 foot long cutoff wall was keyed into an underlying bedrock, which was located an average of 40 feet below the ground surface. Using a slag cement-clay based slurry, a 1E-7 cm/sec or less, nominal 4-inch wide cut-off wall was constructed using the vibrated beam method. Challenges included working around an active manufacturing facility with minimal access to the work area; installing the wall through a very dense glacial till; minimizing soil excavation volumes of potentially impacted soil; and, working around and adjacent to numerous active utility lines without impacting the facility operations. At utility locations, the vibrated beam wall was supplemented with a jet grout panel wall, without the need to bypass or otherwise interrupt any of the plant?s utilities. Quality control consisted of the monitoring and measuring of slurry parameters, survey control, and real-time monitoring and documentation of all critical barrier wall installation parameters. A vibration monitoring plan was also implemented to measure vibrations at utilities and adjacent facility structures. Proper equipment selection, significant up-front planning and close coordination with the facility resulted in a safe and successful project. The work was completed ahead of schedule during the 2009 construction season.

Jan 1, 2010

By Andrew R. Klaetsch, Peter W. Deming

"The Washington Avenue tunnel in Kingston, NY was completed in 1912 to convey combined storm water and sanitary sewage. Over a mile in length, the tunnel was driven almost entirely in bedrock, with the exception of an approximately 170 foot long brick arch segment constructed in soil. About 90 years after the tunnel was put into service, persistent subsidence problems and sinkholes were observed in Washington Avenue above the shield-driven soil tunnel segment, eventually causing the important traffic thoroughfare to be closed. Subsequent tunnel inspections revealed a breach in the brick arch and a significant volume of fine soil within the tunnel. A two-phase remediation program was implemented to control seepage, reduce soil migration, and remedy sinkhole problems. The first phase included in-situ soil densification by vibratory pile probe driving to improve density in shallow sandy soil loosened by ground loss. The second phase included installation of a continuous soilcrete arch structure over and alongside the tunnel, extending to rock or compact glacial till and spanning the length of the soil tunnel segment. Overlapping vertical soilcrete columns were installed through interlayered sandy and clayey silt by jet grouting to form a continuous arch structure, using grout parameters verified by full scale field testing.PROJECT BACKGROUNDThe Washington Avenue tunnel in Kingston, NY (Figure 1) was completed in 1912 to convey combined storm water and sanitary sewage to Rondout Creek by the Board of Water Supply of the City of New York. The tunnel is over a mile in length and constructed primarily in rock. Contract documents indicate the tunnel was designed with a horseshoe shape at least 3 ft wide and 5.5 ft high."

Jan 1, 2016

By Marwa Nabil, Alaa A. Ata

"Recent developments in the analysis of piled rafts has incorporated the load sharing of the raft and the piles to support the superstructure. In the piled-raft system, piles are cast monolithically with the raft and the load is partly transmitted by the raft to the soil directly below it, and partly by the piles to more competent deep soil. While these piles are effective in increasing the bearing capacity and reducing the settlements, they often lead to significant straining actions at the pile head-raft connection which may constitute the weakest link. An attempt to provide a more economical solution, that at the same time overcomes this weak link, is to disconnect the pile heads from the raft and introduce an intermediate cushion of compacted fill. In this case, the piles are considered as reinforcement to the subsoil and will also act as settlement reducers. This paper investigates the load transfers mechanism of the unconnected piled raft with cushion using ABAQUS finite elements Program. The main objective is to provide an in depth analysis of the raft–soil–pile interactions in multi-layered soil under static and seismic loads. The investigated system provides an economical alternative for traditional connected piled raft foundation, where there is no need to reinforce the piles, no need for pile head demolition or expensive waterproofing of the pile head connection. Cost analyses of unconnected versus connected piled raft systems confirmed a cost savings in the construction that may reach from 50 to 70 percent.INTRODUCTIONDesigners around the world have gained more confidence to use the piled-raft as a more realistic system where the raft and the piles share transferring the superstructure loads to shallow and deep soil layers. A further advancement is to use unconnected piled rafts as another practical and economical alternative to the traditional piled rafts. Unconnected piled raft is also synonymous to settlement reducing piles; or simply, soil improvement piles. Liang et al. (2003) has extended the concept of pile-raft-foundation to a new type of foundation called composite piled raft foundation or unconnected piled raft foundation. The foundation is composed of a sand/gravel cushion sandwiched between the raft and piles. The piles group may contain short and long piles. The short piles are constructed of flexible materials such as soil-cement columns or sand-gravel columns, and are used mainly to improve the bearing capacity of shallow soft soil; the long piles, which are made of relatively rigid materials such as concrete, and their main function is to reduce settlements. The cushion plays an important role in mobilizing the bearing capacity of the subsoil and in modifying the load transfer mechanism of the piles. In Shanghai, China, this system of unconnected piled raft has proved to be quite suitable and effective in coastal areas, where deep soft soil deposits exist."

Jan 1, 2016

By Martin D. Larisch, Ronald Damen

The design and construction of temporary working platforms for cranes and piling rigs is a high-risk activity. It requires the careful selection of the appropriate input parameters to obtain the correct load cases, as well as the application of robust and reliable design methods to assess the required thickness and stiffness of the working platform. The document introduces some of the most common and most relevant guidelines for working platform design which are currently used in Australia and New Zealand. The authors will also discuss the basic assumptions and considerations about load transfer from construction plant, debate ground risk, compare the applicability of different design methods for various ground conditions and suggest some common verification methods for working platform certification.

May 1, 2022

By Jonathan G. Cannon

"This paper will describe dynamic pile testing conducted during installation of driven octagonal precast prestressed concrete piles used as the foundation for this bridge. The piles were long and hence spliced. A number of the piles showed damage near the splices and the damage location was near the ground surface so that the damage could be verified using visual inspection. The piles and splice configuration are still in use today without modification. Further WEAP driveability analysis has been conducted which demonstrates the effect of the splice on pile stresses and a likely failure mode. A slight modification is proposed to the splice that should prevent the damage on future projects.INTRODUCTIONThe bridge site is located on the Olympic Way, Route 41, about 20km north of the regional centre of Albury, NSW. For a long distance north of the site the Olympic Way ""shadows"" the main Melbourne to Sydney rail line and is located on the Western side and in close proximity. At the bridge site there was previously a sharp dog-leg in the road and a right angle level crossing with the road changing to the Eastern side of the rail line, eventually joining up with the Hume Highway, which in turn now becomes a ring-road through the eastern outskirts of Albury. The dog-leg and rail crossing had warning signs and bells, speed restrictions and rumble strips to warn approaching motorists to reduce speed. Site distance was exceptionally good.Approximately 2years before construction a group of five ""high spirited"" young men from the local area were driving south on the Olympic Way adjacent to a south-bound train. It is understood they interacted with the train crew for a period of time. Unfortunately the car and train collided at the level crossing and all of the young men were killed. There were outpourings of grief in the local community and a decision was made to replace the level crossing with a road-over-rail bridge.The bridge was highly skewed with two piers and two high level abutments with fill embankments on both approaches.GROUND CONDITIONSThe site is open grazing country with approximately level ground at the site with surrounding low hills. The geology was unremarkable with consistent stiff clays for a considerable depth.The design required driven precast prestressed pile foundations with the piles to be driven to a considerable depth.Hard driving with high tension stresses were evident from the start of driving and a variety of different pre-bore lengths were adopted in an attempt to minimise driving and potential for damage. At the abutments the pile locations were predrilled for at least the full embankment depth.PILESThe piles were 550mm octagonal prestressed concrete with the pier piles being single piece and the longer abutment piles being two-piece with a ""standard"" epoxy glued box splice. Pier piles and the initial length of the abutment piles were 24m. The add-on piece used at the abutments was 12m. Pile concrete was grade 50MPa."

Jan 1, 1900

By Melissa S. Beauregard, Randall A. Pietersen

This study focuses on quantifying the effects of water infiltration on a full-scale energy pile system’s ability to meet the thermal demand of an HVAC system. Theoretically, an energy pile system should increase its thermal capacity after a rain event due to increased moisture content creating an increase in thermal conductivity of the surrounding soil matrix. The United States Air Force Academy has an energy pile research site consisting of 8 full-scale energy piles located below a shower facility. The local colluvium surrounding the piles allows for relatively high water infiltration during rain events. This study uses an 11kW Precision Geothermal Geocube to apply a thermal load on two single-loop piles. A weather station located south of the structure records atmospheric conditions. Results indicate that moderate rain events can caused up to a 23% increase in the system’s thermal exchange capacity. This change is due to the increase in moisture content near the surface, which penetrates to deeper soil layers with time. The time required for moisture to penetrate to greater depths and then dissipate in the soil matrix, explains why increased system performance is seen for over a week following the passing of a singular rain event. 1 INTRODUCTION With a “future-forward” focus, there is an ever-pressing economic and environmental need to use sustainable sources to meet growing energy needs. HVAC is typically responsible for 34% of the overall energy required by commercial buildings and 48% of the energy required by residential buildings (USEIA, 2009; USEIA, 2012). Energy piles are a low cost, sustainable technology that have been used to offset this energy demand incurred by a building’s space heating and air conditioning requirements. An energy pile consists of heat exchanging elements in a closed loop system integrated into a building foundation and connected to a ground source heat pump (GSHP). It is most common for these heat- exchanging elements to be constructed within a drilled shaft foundation due to both construction practices and geometric considerations. This system operates based on the principle that at a certain depth below ground (typically 4 meters) subterranean temperature remains constant at a value equal to the mean annual air temperature at a given location (Kavanaugh et al., 1997). This allows the soil to function as a heat sink for cooling operations and a heat source for heating operations when exchanged within this zone of relatively constant temperature. For the past 25 years, the implementation of energy pile technology in public, residential, and even large-scale architectural complexes has slowly expanded which has created an increase in research into the topic as a result (Brandl, 2006; Hamada, 2007; Sekine et al., 2007; Gao, 2008; Bourne-Webb, 2009; Stewart and McCartney, 2013; Murphy et al., 2014). When pile construction takes place beneath the groundwater table, soil is under fully saturated conditions, maximizing thermal exchange for a GSHP system. Under unsaturated conditions, however, changing moisture contents change thermal conductivity values in a soil, which affect a GSHP system’s ability to meet a thermal demand. The observational data presented in this paper apply to GSHP systems in unsaturated soil conditions.

Jan 1, 2019

By Sung-Ryul Kim, Woong-Jong Park, Juhyung Lee, Si-Hoon Lee

"A bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The model suction buckets were made to have the embedment ratios of 0.5 and 1. The dry model ground was prepared to have two different soil densities by air-pluviation method. A horizontal cyclic load over 104 cycles was applied varying the loading amplitude. Test results showed that the accumulated rotation of the bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the bucket foundations in sandy ground under long-term cyclic horizontal loads.INTRODUCTIONRecently, a bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In terms of economy, a bucket foundation has been considered to be an economical foundation type at sea beds where ground condition is clay or medium dense sand.A bucket foundation resembling a bucket is a kind of suction-installed foundation units. It is a skirted steel foundation which is open at the lower end and closed at the upper end by a lid. The embedment depth ratio (L/D) of a bucket foundation is usually less than one. Figure 1 shows an example of a bucket foundation. Offshore wind turbines are subjected to long-term cyclic loading by wind or currents. A bucket foundation is installed in soil grounds, so the long-term cyclic loading may induce the accumulation of soil deformation.In this study, the accumulated rotations of the bucket foundations in sandy ground were investigated under long term cyclic horizontal load. The number of cycles up to 104 cycles was applied varying load magnitude. The accumulated rotations of the bucket foundations in sandy ground were analyzed based on the test results."

Jan 1, 2016

By Ramanathan Ayothiraman, Anurag Singh

"An experimental program was undertaken to investigate the effects of randomly distributed basalt fibre on the index and engineering properties of Dhanori clay and to compare its performance with the properties of soil reinforced with polypropylene fibre. In the present investigation, 7 groups of soil samples were prepared at four different percentages of basalt fibre and polypropylene fibre content and tests were done for measuring their consistency limits, compaction characteristics, unconfined compression strength and consolidation properties. The test results indicate that the inclusion of basalt fibre in Dhanori clay resulted in significant improvement in properties. The improved properties are not comparable with polypropylene fibres, nevertheless, the improvement by basalt fibres is able to meet the typical design target values and the cost is very much less than synthetic fibres. More importantly, basalt fibres are environment friendly.INTRODUCTIONConstruction of buildings in low lands with engineered filling, flexible and rigid pavements for highways/airfields, and embankments for highways/railways are also part of major infrastructural development in addition to construction of tall buildings, bridges/fly overs, major dams and underground structures. The later projects require different improvement techniques than that is adopted in the former projects. Ground improvement techniques such as use of reinforcement inclusions within soil found as an effective and reliable technique. Especially such modification by fibre reinforcement, is primarily possible in engineered filling, pavements subgrade and embankments, where surface mixing is easier; and may not be feasible when stabilization/modification is required for deeper depths. In comparison with conventional reinforcement using geosynthetics (strips, geotextile, geogrid, etc.), there are some advantages in using randomly distributed fibre as reinforcement. In past few decades, the discrete fibres are simply added and mixed randomly with soil, in much the same way as cement, lime, or other additives.There are several studies (Ziegler et al. 1998; Puppala et al. 2000; Bei-xing et al. 2004; Cai et al. 2006; Tang et al. 2007, 2012, 2016; Abdi et al. 2008; Viswanadham et al. 2009; Le et al. 2015) that investigated the behaviour of polypropylene fibre-reinforced soil and reported that an increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential. The length of fibres had an insignificant effect on soil characteristics, whereas fibre contents proved more influential and effective. A study on rubber fibre conducted by Hambirao and Rakaraddi (2014) mentions that tensile cracking of clays can be improved with the inclusion of short rubber fibres, optimum fibre content was about 15 % of weight of soil. Several experimental studies (Babu et al. 2008; Chaple and Dhatrak 2013; Vibhakar and Nahta 2014; Soundara and Senthilkumar 2015; Goyal et al. 2015; Jayasree et al. 2014, 2015) were conducted on coir fibre-reinforced soil and concluded that it helped in reducing the swell potential and 1% fibre by weight of the soil almost doubled the CBR value. Martins et al. (2015) found that 4% of sisal fibre by weight of the soil reduced the visibility of cracks. Pillai and Ayothiraman (2012), Ayothiraman et al. (2014) and Sahu et al. (2016) have demonstrated that human hair fibres can be used to improve the properties of both fine grained and coarse grained soils."

Jan 1, 1900

By Ezra Ballinger, Matthew R. Glisson

Located in downtown Fargo, North Dakota, the Block 9 Redevelopment project site contains highly- compressible soils in the upper 100 feet with groundwater about 10 to 15 feet below the existing ground surface. The owner prohibited using driven piles to avoid disturbing neighbors of the project and historically, drilled shafts are used in Fargo as a reduced noise and vibration alternative to driven piles. However, developments over the last 20 to 30 years in drilling equipment, load testing and integrity testing resulted in the project team identifying augered cast-in-place piles as a suitable alternative for this project. To reduce the risks associated with using a relatively unproven foundation system in the area, the project team used the design-build delivery method for foundation design and construction. The team also specified compression load testing and higher-than-normal integrity testing. A successful bi-directional load test validated the design parameters for the augered cast-in-place pile while thermal integrity profiling gave the team confidence that these piles would perform similarly to the test pile. PROJECT DESCRIPTION The Block 9 Redevelopment project goal was to turn an existing, at-grade parking lot in downtown Fargo, North Dakota into a public outdoor plaza, a mixed-use building and a parking ramp. The project provides new offices, retail spaces, a hotel, a restaurant and private apartments. Situated in the southeast quadrant at the intersection of Broadway and 3rd Avenue North, the project site wraps around a bank building that was to remain. According to aerial photographs, the eastern portion of the site contained a public parking ramp that was constructed between 1952 and 1976, and subsequently demolished between 2009 and 2010. The western portion of the site had some combination of buildings and surface parking visible in aerial photographs taken between 1952 and 1979. Since 1984, aerial photographs show the western portion of the site being entirely surface parking. The redevelopment included the construction of three structures: the Tower, the Podium and the Parking Ramp, as shown in Fig. 1. With plan dimensions of roughly 100 feet by 100 feet, the Tower has 1 level of below-grade parking and 19 above-grade levels rising to a height of about 230 feet above grade. The Tower contains eight levels of commercial office space, four levels of hotel, six levels of residences and a mechanical level. This configuration resulted in column service loads ranging between 435 and 2,685 kips. The Tower core area has a total service load of about 30,000 kips.

Jan 1, 2019

By Lance Rasband, Richard Hanke

"Seattle Tunnel Partners (STP) started mining on Seattle’s SR99 tunnel on July 30, 2013, working slowly through a 15 ft (4.6 m) thick fiber-reinforced concrete headwall. Once through the headwall, the machine would move through roughly 400 lineal ft (122 m) of jet grout-improved soil at a rate slightly over 6 ft (1.8 m) per day. It was anticipated that once through the improved area, Bertha—the world’s largest tunnel boring machine—would move at a rate of 35 ft (10.7 m) per day. By the end of October 2013, Bertha had mined roughly 430 ft (131 m), averaging 4.73 ft (1.4 m) per day, and had begun mining within native soils. By the start of December 2013, tunneling reached the 800 ft (244 m) mark and Bertha averaged 12 ft (3.7 m) per day, achieving as much as 42 ft (12.8 m) of progress on some days. However, on December 6, 2013, Bertha began to stumble and all progress quickly came to a halt. Preliminary InvestigationInitial reports stated that an obstruction had stopped the machine in its tracks. Malcolm Drilling received an early morning call on Sunday, December 8, 2013, from STP to rapidly mobilize a Bauer BG-50 drill rig with crews to investigate what was hindering Bertha’s progress. Malcolm’s equipment and crews flew into action and were completely mobilized and operational by mid-week. The preliminary investigation involved installation of 10 deep dewatering wells to reduce the hydrostatic head within the ground around the machine and allow STP personnel to inspect the cutter head from within the shaft for presence of obstructions. By the close of December 2013, the wells were installed and the dewatering system was fully commissioned. STP crews were then able to inspect the cutter head and found small fragments of a steel pipe wrapped around the outside of the shield. The steel was apparently from an abandoned 10 in (0.25 m) diameter monitoring well casing previously installed by WSDOT (Washington State Department of Transportation) to monitor groundwater conditions for the design and planning of this very project. After the steel was cut out of the head and cleared from Bertha’s path, she attempted to move forward but was only able to manage a slow crawl"

Jan 1, 2015

By Sandeep Pattnaik

Spring stiffness of soil and rock at different depth is often required for a pile structural model. If the pile is rested in multiple layers of soil, then it is rather more complex to simulate the soil in a structural model. The spring stiffness will vary based on density of soil strata over the depth. When a pile is socketed in weathered rock followed by a soil layer, a sudden change in subgrade modulus can influence the pile deflection drastically. Determination of soil spring and simulation of the pile in this condition required correct interpretation of subgrade modulus. The conventional approach of pile spring calculation underestimates the spring stiffness by ignoring underlaying stiffer layers. A finite difference method (FDM) of analysis can reasonably estimate the p-y of soil / rock based on subgrade modulus of each layer. However, the transition between the layers can be better simulated as per the deflection pattern of the pile. The lateral deflection of the pile is mainly dependent on the stiffness of soil layer surrounded by the pile. Generally, the lateral influence of a pile varies from 4D to 6D depending on the soil type. Therefore, soil spring stiffness around the pile would require special attention of a Geotechnical engineer to avoid uncertainty in the prediction of pile behaviour. In this paper, emphasis has been given to develop an approach for pile spring stiffness design. A standard software program LPile has been used to develop p-y curves of soil and rock layers at different depths and then converted to soil/ rock springs over the depth. Modulus of Subgrade Reaction as given in IS 2911 (Part2) was also used to correlate the spring value for different type of soil. Obtained analytical results were compared with full scale field trial for lateral deflection of pile. A good agreement between these two approaches has been established. The effect of soil structure interaction in the structural model shall be simulated by assigning an equivalent vertical and horizontal soil spring, which is developed by Winkler’s soil spring approach. A simplified design principle for calculating the pile spring is discussed in this paper. This approach has been extensively used in Mumbai metro elevated line pile design.

Nov 1, 2022