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By V K. Panwar, Sampat Raj

At a Fertilizer plant located in the southern part of India, 74 numbers of pump foundations have shown non-uniform settlements causing the tilting of pump foundations under self-weight primarily due to the presence of varying thickness of the heterogeneous subsoil beneath the pump foundations and soil erosion because of water seepage through deeper excavations in the close vicinity. Various corrective measures have been explored and taking due cognizance of the prevailing subsoil conditions, site constraints, and constructability aspects, micropiling has been adopted. This paper presents the site problem and details of remedial measures adopted for rehabilitation of the distressed pump foundations. The main objective of this paper is to provide guidelines for designer during design and detail engineering stage to avoid similar nature of problems and also to provide a solution concept to tackle similar nature of problem(s) if encountered at site.

Nov 1, 2022

By Tsuyoshi Honda, Kazuhiro Kaneda, Masayuki Imai, Kazuo Konishi, Kunio Higashinaka

"In recent years, the demand for measures to control liquefaction of existing airport runways and harbor structures has increased. However, from the perspectives of constructability and cost, application of grid-form deep mixing walls to these types of structures requires the formation of wider grid spacing as compared with conventional designs. In this research, we focused on the extent of liquefaction and ground surface settling when grid spacing is made wider than conventional designs. We conducted centrifuge model tests, and confirmed the liquefaction suppression effect when grid-form modifications involving wide grid spacing are adopted under asphalt pavement. The tests were conducted under conditions that included changing the grid spacing and groundwater level. When the groundwater level was high, an increase in water pressure was observed, even within the grid. However, when the groundwater level was low, the increase in water pressure inside the grid was suppressed. We also found that if the generation of water pressure can be suppressed, the amount of settling due to liquefaction can also be controlled.INTRODUCTIONOne construction technique used as a countermeasure to liquefaction is grid-form deep mixing walls. Grid-form deep mixing walls are a construction technique for which improved grid-shaped wall bodies are built into the ground below the surface using a deep mixing method. This construction technique minimizes shear deformation by surrounding liquefied ground with improved wall bodies, thereby preventing liquefaction (Fig.1). With conventional designs, grid-form deep mixing walls determine the grid spacing that can deter liquefaction based on a ratio of the grid spacing L to the improved depth H (ratio = L/H). Ordinarily, designs are implemented with an L/H ratio of 0.8 or less (PWRI, 1999).In recent years, a demand for measures to control liquefaction of existing airport pavement and harbor structures has increased. However, when liquefaction countermeasures are implemented at these types of facilities and structures, the construction work must be implemented while the facilities and structures remain in service. Therefore, temporal and spatial constraints must be considered. In addition, unlike conventional liquefaction countermeasures, performance requirements are such that, even if some degree of liquefaction is allowed, the performance is acceptable as long as the amount of settlement is within a predetermined value. Therefore, if grid-form deep mixing walls are applied to these structures, grid spacing that is wider than conventional standards is desired."

Jan 1, 2015

By Saieb Haddad, Henry Pate

"Building retaining walls in an urban area is becoming more difficult due to right-of-way restraints. Using standard concrete cantilever walls requires a construction easement behind the walls for installation, which for the most part is unavailable. To install these types of walls in a limited right-of-way requires extensive temporary walls to minimize the construction easement. Top-down construction walls utilizingtie-back anchors for support require either the purchase of the right-of-way or underground easements in the area of the anchors.These problems faced the Department on Interstate 75 widening in Knoxville, TN in an area of a large cut. A multi-story Insurance Building and a large commercial Retail Center were located at the top of the cut. To prevent any impact on the buildings, the walls had to be placed within a limited area. The option of buying the properties was prohibitively expensive. Due to the height of the two walls and the variability of the underling rock line, contiguous caisson pile cantilever walls were contemplated as the only wall type that would be appropriate. The cost of the two walls was estimated to be very close or even higher than the cost of purchasing the two buildings. The Department believed that there must be a better way to deal with the problem. A vertically tied-down pile frame wall constructed from the top-down with a concrete facing was developed. This allowed the construction of the walls to be restricted to the available limited area and provided substantial savings for the State.INTRODUCTIONThe widening of I-40/75 has been a major transportation project in the Knoxville area which is being constructed by the Tennessee Department of Transportation. The project includes 18 Retaining Walls and 13 Bridges.Two of the 18 Retaining Walls, refer to Figure 1, are to support two valuable properties, one being an insurance company housed in a multi-story office building and the other a suburban shopping center which were appraised at $13.0 million and $5.0 million respectively. Due to the 31 ft. (9.5m) maximum height of each of the two Retaining Walls and the limited Right-of- Way of 15.0 feet (4.6m), a contiguous caisson pile cantilever wall was proposed for each of the two retaining wall sites with an estimated cost of $12.0 million each. The contiguous pile cantilever Wall is comprised of a line of caisson piles socketed into underlying competent bedrock. The design required that 4 ft. (1219mm) dia. piles be installed at 6 ft. (1.83m) centers, socketed into rock in order to provide lateral stability and restrict lateral wall movement to acceptable limits. The line of caissons would be fronted with a cast-in-place concrete face wall"

Jan 1, 2007

By Aly Mohammad, Dongyi Yue

"The design of rock sockets for drilled shafts and piles proves to be a challenge for the Design Engineer. The magnitude of loads on the shaft and the behavior of the rock are critical in determining the required socket length. Several acceptable methods are available in the literature to analyze a rock socket under a combination of axial loads, lateral loads and moments. This paper will present a state-of-the-art methodology to analyze rock sockets utilizing deformation characteristics of the rock. This design methodology was implemented in the design of a major project in New York City.The project discussed herein is a marine transfer station planned for construction at East 91st Street along the East River in Manhattan. In order to support the piers and platform structures at a site with relatively shallow depth of the bedrock, rock sockets were required for the drilled shaft foundations. Rock sockets were utilized to provide the required fixity to the foundations and the structures. Acting at the top of the rock sockets are large shear forces and moments created by the lateral loads transferred from the structure.Upon review of the available techniques, a simplified method was proposed and used to analyze the rock sockets with a significant magnitude of lateral loading. The method recognizes two mechanisms through which the lateral shear and moment are transferred to the rock; a) load transfer through horizontal resistance of rock and b) the vertical shear resistance of the bond between socket and rock.The first load transfer mechanism was analyzed using the p-y curve method based on a rock model developed by Reese. The second was analyzed using a bond stiffness derived from the formula and curves utilized in the AASHTO Specifications for calculation of rock socket displacement. By comparing the two mechanisms, the main contribution to the large horizontal shear force that developed in the rock socket is identified.The paper will present a summary of the design methodology utilized in determining the length of the rock socket. It is believed that the presented method will provide substantial cost saving in selecting the most economical and efficient design length."

Jan 1, 2005

By Saieb Haddad, Henry Pate

"Building retaining walls in an urban area is becoming more diffi cult due to right-of-way restraints. Using standard concrete cantilever walls requires a construction easement behind the walls for installation, which for the most part is unavailable. To install these types of walls in a limited right-of-way requires extensive temporary walls to minimize the construction easement. Top-down construction walls utilizing tie-back anchors for support require either the purchase of the right-of-way or underground easements in the area of the anchors.These problems faced the Department on Interstate 75 widening in Knoxville, TN in an area of a large cut. A multi-story Insurance Building and a large commercial Retail Center were located at the top of the cut. To prevent any impact on the buildings, the walls had to be placed within a limited area. The option of buying the properties was prohibitively expensive. Due to the height of the two walls and the variability of the underling rock line, contiguous caisson pile cantilever walls were contemplated as the only wall type that would be appropriate. The cost of the two walls was estimated to be very close or even higher than the cost of purchasing the two buildings. The Department believed that there must be a better way to deal with the problem. A vertically tied-down pile frame wall constructed from the top-down with a concrete facing was developed. This allowed the construction of the walls to be restricted to the available limited area and provided substantial savings for the State. INTRODUCTIONThe widening of I-40/75 has been a major transportation project in the Knoxville area which is being constructed by the Tennessee Department of Transportation. The project includes 18 Retaining Walls and 13 Bridges. Two of the 18 Retaining Walls, refer to Figure 1, are to support two valuable properties, one being an insurance company housed in a multi-story offi ce building and the other a suburban shopping center which were appraised at $13.0 million and $5.0 million respectively. Due to the 31 ft. (9.5m) maximum height of each of the two Retaining Walls and the limited Right-of- Way of 15.0 feet (4.6m), a contiguous caisson pile cantilever wall was proposed for each of the two retaining wall sites with an estimated cost of $12.0 million each. The contiguous pile cantilever Wall is comprised of a line of caisson piles socketed into underlying competent bedrock. The design required that 4 ft. (1219mm) dia. piles be installed at 6 ft. (1.83m) centers, socketed into rock in order to provide lateral stability and restrict lateral wall movement to acceptable limits. The line of caissons would be fronted with a cast-in-place concrete face wall."

Jan 1, 2007

By Ryan P. Sullivan, G. Alan Klevens, Jian Huang

"BACKGROUNDLake Hamilton in Hot Springs, AR was created in 1932 when the Arkansas Power and Light Co. completed Carpenter Dam on the Ouachita River to generate electricity. Today, the 7,200-acre (2,914 hectares) impoundment is one of Arkansas’s most popular recreational and residential lakes.U.S. 70 crosses Lake Hamilton by means of a seven-span bridge featuring nine steel girders per span. Constructed between 1982 and 1984, the 1,410-foot long (430m) bridge carries four lanes of traffi c across the lake. The bridge is supported by six intermediate reinforced concrete piers composed of hammer heads, stems, footings and seals, which sit on the underlying rock. (See Figure 1). The bridge rises to a maximum of 33 feet (10m) above the surface of the lake and the footings and seals extend a maximum of 29.5 feet (9m) below the surface of the lake. The seals are situated on hard, fractured sandstone and shale.Routine underwater inspections in 1993 revealed large cracks in the lean seal concrete and refl ective cracks in the reinforced concrete footings. Infrastructure Engineers, Inc., The Arkansas State Highway and Transportation Department’s (AHTD) design consultant, then conducted an in-depth underwater inspection of the pier foundations. The investigation included cross-hole sonic logging, singlehole sonic logging, visual examination and strength testing of core samples, and petrographic analysis.The investigation revealed extensive cracking and low-strength concrete within the seals of all intermediate pier foundations. Many voids within the seal concrete had become fi lled with silt. There was evidence of continued seal deterioration between underwater inspections.AHTD and its engineers considered three rehabilitation solutions in the preliminary engineering stage: micropiles, a cofferdam supported concrete jacket, or a pile supported concrete jacket. The three alternatives were estimated to cost $1,250,000; $4,320,000; and $3,030,000 respectively. All three options would transfer the loads from the pier footing directly to the rock below, bypassing the seal concrete."

Jan 1, 2007

By Ryan P. Sullivan, G. Alan Klevens, Jian Huang

"BACKGROUNDLake Hamilton in Hot Springs, AR was created in 1932 when the Arkansas Power and Light Co. completed Carpenter Dam on the Ouachita River to generate electricity. Today, the 7,200-acre (2,914 hectares) impoundment is one of Arkansas’s most popular recreational and residential lakes.U.S. 70 crosses Lake Hamilton by means of a seven-span bridge featuring nine steel girders per span. Constructed between 1982 and 1984, the 1,410-foot long (430m) bridge carries four lanes of traffi c across the lake. The bridge is supported by six intermediate reinforced concrete piers composed of hammer heads, stems, footings and seals, which sit on the underlying rock. (See Figure 1). The bridge rises to a maximum of 33 feet (10m) above the surface of the lake and the footings and seals extend a maximum of 29.5 feet (9m) below the surface of the lake. The seals are situated on hard, fractured sandstone and shale. Routine underwater inspections in 1993 revealed large cracks in the lean seal concrete and reflective cracks in the reinforced concrete footings. Infrastructure Engineers, Inc., The Arkansas State Highway and Transportation Department’s (AHTD) design consultant, then conducted an in-depth underwater inspection of the pier foundations. The investigation included cross-hole sonic logging, singlehole sonic logging, visual examination and strength testing of core samples, and petrographic analysis.The investigation revealed extensive cracking and low-strength concrete within the seals of all intermediate pier foundations. Many voids within the seal concrete had become filled with silt. There was evidence of continued seal deterioration between underwater inspections.AHTD and its engineers considered three rehabilitation solutions in the preliminary engineering stage: micropiles, a cofferdam supported concrete jacket, or a pile supported concrete jacket. The three alternatives were estimated to cost $1,250,000; $4,320,000; and $3,030,000 respectively. All three options would transfer the loads from the pier footing directly to the rock below, bypassing the seal concrete."

Jan 1, 2007

By Martin B. Hudson, Andrew K. Cho, Rolff B. Knobel, Les R. Chernauskas, Jonathan L. Ernst

ABSTRACT The Bruce Museum, located in Greenwich, Connecticut, is home to an extensive display of art and natural history exhibitions. A large addition was designed to be constructed adjacent to the museum requiring new spread footings to be installed up to 16.5 feet below the existing foundations. The soil conditions at the site consist of highly variable sand and gravel overlying weathered rock and sound bedrock. The Contract Documents called for traditional foundation underpinning. Traditional underpinning techniques, however, presented two major challenges on this Project; (1) deep underpinning pits would be required involving multiple levels and staging with tieback support and (2) the highly variable soil and bedrock composition and elevations presented uncertainty in the design and construction of the pits. In lieu of traditional underpinning, Geosciences Testing and Research, Inc. (GTR) proposed an “active” soil nail underpinning system. A major reason that the soil nail underpinning option was feasible, related to the fact that the soil nails and facing could be installed slightly in front of the existing footings rather than directly underneath the existing footings. The soil nail wall design involved one to four rows of soil nails with nail positions and wall depth able to be adjusted “on the fly” as excavation progressed depending on the field conditions encountered. To create the “active system,” the soil nails were pre-loaded to mitigate wall deformations that would be associated with a standard passive soil nail wall design. To evaluate the performance of the active soil nail wall and confirm design assumptions, an extensive automated monitoring, on-site testing and inspection program was proposed and executed by GTR to monitor deformations of the wall and the museum in real-time, evaluate and confirm bedrock and soil bond stresses and ensure that each soil nail was pre-loaded and locked off. Careful analysis, planning, and use of the observational method illustrates the importance of collaboration between design and construction personnel and applying engineering judgement throughout construction. The use of the observational method includes the potential for modifying design based on conditions observed. This paper presents a unique case study of the “active” soil nail underpinning system to support and protect sensitive structures, close collaboration between design and construction facilitated by real-time deformation monitoring, and its successful application as a safe and cost-effective alternative to traditional underpinning.

Oct 1, 2022

By Don W. Dotson

In 1962, Kondner prepared several papers dealing with hyperbolic stress-strain response of cohesive soils. The following year, Brinch Hansen proposed 80% and 90% failure criteria for stress-strain behavior of cohesive soils. Fellenius was instrumental in popularizing these failure criteria for pile load tests and offered a direct solution equation for the failure load according to the 80% failure criterion. Since the 90% Criterion has been incorporated into the International Building Code, equations for the direct solution of the failure load at the 90% Criterion would be useful to practicing engineers. This Technical Note supplies the derivation methodology for the 80% Criterion and provides expressions to determine the load and deflection at failure for the 90% Criterion.

Aug 1, 2013

By Abolfazl Eslami, Fatemeh Valikhah

"Complexity in soil-foundation interaction and subsoil nonlinear behavior cause difficulties and uncertainties in evaluating the actual values of foundation design factors such as settlement. The acquired continuous records of Cone Penetration Test (CPT) can be used to determine the soil profile and characteristics those are applicable in the geotechnical design. In this paper, it has been attempted to present a new non-linear stress-strain approach to estimate the foundations settlement by using CPT data in the form of soil behavior classification charts. This new approach is based on Janbu method (1960s and also 1998). Instead of using fixed and constant values for stress exponent (j) and modulus number (m), continuous coefficient variations can be used. The proposed approach also can be used as a new method to predict pile group settlement. A data bank has been compiled containing twenty-two practical case histories to investigate the accuracy of the predictions made by the proposed and available common methods. The comparisons indicate that the proposed approach is relatively able to predict the settlement close to their real values. Therefore, it can be considered as an alternative method based on valuable CPT data and nonlinear stress-strain approach for foundations and pile groups settlement estimation.INTRODUCTIONComplexity in soil behaviour for settlement analysis is the result of non-linear and time dependent stressstrain behaviour of soils, their elasto-plastic performance under loading and unloading situation and also effects of stress history (Holtz et al., 2011; Fellenius, 2015). Hence, many relations and equations have been proposed to predict foundation settlement, where most of them are based on typical different parameters such as soil stiffness (E), foundation width (B), contact pressure (q) and pressure developing in depth (Janbu, 1967 also 1998; Briaud and Gibbens, 1999; Uzielli and Mayne, 2012).The Janbu approach for settlement estimation, proposed by Janbu in the early 1960s, combines the basic principles of linear and non-linear stress-strain behaviour of material. The method is applied to all types of soils. The relation between stress and strain is a function of two non-dimensional parameters which are unique for any soil: a stress exponent, “j”, and a modulus number, “m”. The Janbu relations are derived from the definition of tangent modulus by the following expression:"

Jan 1, 2017

By Gust Van Lysebetten, Monika de Vos

The objectives of monitoring geotechnical structures can be very diverse, including optimisation of the design, quality control, long term performance assessment, and approval of innovative execution techniques. In this context, new measurement techniques, based on optical fibres, offer the possibility of accurate strain and temperature monitoring with very small sensors and limited numbers of cables. This paper briefly presents optical fibre sensing techniques and illustrates their application to geotechnical structures by means of some projects, carried out by the Belgian Building Research Institute (BBRI).

May 1, 2022

By George Burke

"Many soil mixing methods have evolved over the years, but the Trench Cutting Re-mixing Deep method (TRD) was developed in Japan, circa 1993, to construct continuous uniform cutoff walls, without the need for an open trench. TRD mixing has been used on over 300 projects in Japan for excavation support, groundwater barriers, liquefaction mitigation, soil improvement and pollution containment. To date, TRD mixing has been used on only three projects in the United States: a test cell in Long Beach, Calif., for seawater intrusion barrier in 2004; a groundwater barrier at a wastewater treatment plant in Lincoln, Calif., in 2005; and presently at Herbert Hoover Dike surrounding Lake Okeechobee in southeastern Florida.The most notable benefits of TRD are its abilities to overcome difficult geology, such as layered rock and dense cobbles and gravels that hinder other soil mixing methods, and to create extremely high-quality walls. The method is ideal for situations in which access precludes the use of more traditional methods due to spoil control, such as waterways and congested urban environments or subsurface obstruction/difficult ground. Spoil disposal is minimized since TRD mixes the soil in place.TRD mixing has a horizontal continuity advantage over traditional multi-auger deep soil mixing (DSM) systems. Because DSM systems create walls by overlapping soil-cement columns, the auger may be deflected by difficult ground, and gaps are possible. Gaps may also occur when constructing an exceptionally deep wall due to the possibility of auger deviation from its required vertical alignment.The method also has a homogeneity advantage in layered soils. Because DSM constructs columns by rotating the defined length mixing tools up and down the soil profile while injecting binder, strength and permeability in each layer will vary. The TRD method vertically mixes the entire profile and core samples show highly uniform strength. It is most cost-effective in deep difficult ground such as layered rock or dense cobbles and gravels."

Jan 1, 2009

By Tsunenobu Nozaki

"Basically, the “Press-in Piling Method” was invented to eliminate construction nuisances, such as noise and vibration which have been serious unsolved problems for advancing societies over a long time. In the construction industry, piling works have been a major cause of noise and vibration, because most piling methods utilize dynamic load to install piles into the ground. The secret of the Press-in Piling Method is to utilize static loading to install pre-formed piles rather than dynamic load. The piles are hydraulically gripped and jacked into the ground by the special piling rig known as the “Silent Piler”. Therefore, the piles can form a robust and firm foundation, which is another advantage of the Press-in Piling Method.The Press-in Piling Mechanism and Implant Foundations The basis of the Press-in Piling Method is simple. The Pres-in Piling Machine installs a preformed displacement pile into the ground by static jacking force. The reaction for the Press-in Force is generated by gripping previously installed piles, which are called “Reaction Piles”. Due to this, the Press-in Piling Machine can produce a powerful piling force whilst only requiring minimal machine size.With the Press-in Piling Method, as piles are pressed into the ground, they are incorporated with the surrounding soils, which provides a large bearing capacity and passive horizontal resistance. These embedded foundations which are firmly anchored into the ground are known as “Implant Foundations”. Being embedded into the ground, the foundations are resilient and maintain their serviceability even in the worst credible design conditions."

Jan 1, 2015

By Scott M. Doehla

A proposed rehabilitation of a 200,000 sf, 75-foot high steel-frame building at the former U.S. Navy Yard in Brooklyn, New York required the review of existing foundation data and an investigation of the foundations with respect to their condition. The building was constructed in stages between 1856 and 1933, including several expansions and interior equipment with isolated foundations. The building has clear spans on the order of 50 feet and at one time supported cranes allowing transport of heavy equipment through the building. The proposed rehabilitation is to include a food manufacturing center and office space having multiple stories. Original construction drawings, available from the Brooklyn Navy Yard Development Corporation?s drawing archive, were reviewed to determine the foundation system supporting the structure. The original drawings provide a window into the methods utilized during late 19th and early 20th century pile foundation construction. The review revealed that the building is supported by pile foundations ranging from timber to concrete-filled steel pipe (depending on the year of construction). Annotations including pile driving records were available on some drawings indicating the design and as-built capacity (using the ENR formula for driving resistance). An investigation consisting of test borings was performed to identify the subsurface conditions underlying the building for evaluating theoretical capacity of the piles. A test pit investigation was performed against existing columns within the structure to expose the piles and pile caps for inspection pertaining to pile condition. The test pit investigation revealed methods utilized during original construction to integrate new columns with existing floor slabs, the use of below-grade brick arches to support a floor slab, and the condition of timber piles which were likely installed up to 120 years ago. The observations made within the test pits were compared with original drawings to evaluate the accuracy of these drawings.

Jan 1, 2008

By C. Guney Olgun, Charles Elks, Sherif L. Abdelaziz, James R. Martin, Christopher Fox, Pier Luigi Iovino, Fatih Catalbas, Pierre Gouvin

"Energy piles are a new innovative renewable energy technology to access and exploit the relative constant temperature of the ground for efficient heating and cooling of buildings. Examples of energy piles include drilled shafts, continuous flight auger (CFA) piles, driven piles, and micropiles. A field test setup was installed at the Virginia Tech Geotechnical Research Facility to study energy piles. The field test consists of a total of five micropiles 25 cm (10 inches) in diameter, four of which were equipped with circulation loops. The test piles extend to a depth of 30.5 meters (100 feet) and are heavily instrumented with strain gauges and temperature sensors. Several observation boreholes were formed around the test piles to monitor ground temperatures. Thermal conductivity tests and field load testing were performed to investigate the behavior of Energy Piles. This paper presents results of the thermal conductivity tests and thermo-mechanical field load test performed as part of this field investigation.IntroductionThere is a developing trend around the world to explore alternative energy sources. The main driving forces are growing global energy demand, depleting natural resources and the adverse effects of greenhouse gas emissions from fossil fuel consumption. Geothermal energy is one of the promising renewable sources that can be utilized to offset such trends. However the use of geothermal energy has been limited mainly to certain hot spot areas where it is used either for district heating and/or electricity generation. Ground temperatures below a depth of about 6 meters (20 feet) remain stable compared to outside air temperatures, typically lying between 8-23°C (46-73°F) at most U.S. regions. The constant temperature and heat storage capacity of near surface soils in any region represent a tremendous potential of stored energy that can be used for heating and cooling of structures."

Jan 1, 2017

By W. Morgan NeSmith

A drilled displacement pile program was utilized for the expansion of an existing power plant in Cohasset MN adjacent to the Mississippi River. The drilled displacement (DD) pile is an innovative foundation type that provides exceptional value in some geologies. In the U.S., DD piles have typically been used in coarse-grained soils due to the large friction capacities that can be generated by the piles in these conditions. This project was the first large scale experience for the project team where it was anticipated that significant portions of the DD pile capacity would be developed in primarily fine-grained soils. The project site consisted primarily of variable amounts of fill overlying predominantly low plasticity alluvial silts. In some cases, alluvial silty sand layers were encountered within the expected pile installation depths. Alluvial sands were typically encountered below the silts, in some cases within the expected pile installation depths. The project team developed a probe and pile load test program to address the variable subsurface conditions across the site. The program included monitoring various parameters (including applied torque and tool penetration rate) during the drilling portion of the pile installation using recently developed data acquisition techniques. This data was used to estimate the rig energy, or Installation Effort (IE), required for pile installation. IE profiles from the test and indicator piles were compared with subsurface data available from a number of previous site characterizations. Additionally, Cumulative IE values were compared to an in-house database of IE vs. DD Pile Capacity. Final production pile toe levels were based primarily on IE values selected from this comparison. The IE data collected during production was also used to address large variations in pile-cutoff elevation (relative to a fairly uniform ground surface elevation).

Jan 1, 2008

By Deep Foundation

Whenever an organization launches an initiative, the question arises whether that initiative has staying power. Or is the initiative, as is quite often the case, merely a fad; that is, just an activity that suddenly becomes popular, but which does not stay popular for very long. When the Federal Highway Adminis- tration (FWHA) started its Advanced Geotechnical Methods in Exploration (A-GAME) initiative, that question was addressed, especially considering the fact that up to 50% of major infrastruc- ture projects suffer impacts to schedule or cost due to geotechnical issues. Many of these issues relate to risks identified directly or indirectly to the scope and quality of site character- ization work. Effective site charac- terization is critical for recognizing. potential problems that may affect design and construction and for ensuring safe, well-performing and cost-effective projects. Grounded on that, knowledge of all available site investigation methods should continue to be shared widely and the application of those methods should be encouraged on an ongoing basis throughout the project lifecycle. The A-GAME initiative covers five technologies: Cone penetration testing (CPT), monitoring while drilling (MWD), electrical geophysical methods, seismic geophysical methods, and optical and acoustic televiewers. Of these, three soil and rock investigation methods were highlighted that are underutilized not only here in the U.S., but also in many places around the world: CPT: a well proven and established method for soil characterization that turned 90 last year, in which continuous in-situ data are col- lected quickly and consistently. Geophysics: the science that assesses the physical properties of the soils and rock using seismic and electrical techniques, which con- tinues to advance in leaps and bounds as the application of well- understood technologies become more powerful.

May 1, 2023

By Peter Middendorp, Gerald E. H. Verbeek

"This paper will describe a brief history of the method of characteristics as an accurate solution of the wave equation, and the author's experiences with the method of characteristics over a period of 30 years.As a result of the offshore pile driving activities associated with the development of the North Sea oil fields in the 1970's, two Dutch companies initiated extensive research efforts. Heerema started to research the dynamic behavior of soil during driving and HBG (Hollandsche Seton Groep) extended the method of characteristics with a straightforward theoretical solution for the shaft friction along a pile.The research institute TNO started the development of the wave equation program TNOWAVE in the late 1970's based on HBG's friction model extension for the method of characteristics. Today the program has a worldwide application in the field of pile testing. This paper will describe its development and application over time and its relation to today's applications for driveability studies for impact hammers (PDPWAVE) and vibratory hammers (VDPWAVE), signal matching for Dynamic Load Testing (DL TWAVE), Pile Integrity Testing signal matching (SITWAVE), and Statnamic simulation (STNWAVE).The paper will highlight that these developments have been the result of multi-disciplinary and multi-national efforts and encourage geotechnical engineers to seek further developments of the wave equation program in a similar manner. Finally, the paper will indicate some areas where such further developments are required."

Jan 1, 2005

By Andrew Budek

"Analytical and experimental work has shown that achieving the full inelastic lateral capacity of a pile may require the formation of a plastic hinge below ground level, in the pile shaft. The confining action of soil about the pile shaft was further been shown to greatly enhance the ductility capacity of the pile. An experimental program was therefore undertaken to build in the effect of external confinement through the addition of a GFRP jacket to the subgrade plastic hinge region. Two piles were thus modified, and compared to an unjacketed pile in a test rig which simulated a subgrade moment pattern and soil confinement. The ductility achieved by the jacketed piles was found to be substantially lower than an unjacketed control specimen. Failure mode of the jacketed specimens was also undesirable, involving complete tendon rupture and sudden loss in capacity IntroductionSeismic loading of concrete pile shafts can result in a demand for inelastic response. In the case of a superstructure supported by a single pile (i.e., a pile-column forming a single-column bridge pier, in which there is no rotational restraint at the top of the pile}, a plastic hinge will form below grade, at a depth which varies with soil properties and above-grade height of the center of seismic mass.In the case of a superstructure supported by multiple piles, there is rotational restraint, and the connection will experience inelastic action first. However, development of the full lateral inelastic capacity of the pile may call for the formation of a second, subgrade plastic hinge (fig. 1 )."

Jan 1, 2005

By Jørn Thomsen, Christoffer Brodbaek

"As governments increasingly accord high priority to sustainable energy, policymakers are finding that wind energy has a long track record as a proven alternative to conventional energy supply.Over the past two decades, wind turbine projects have been constructed offshore because of more stable offshore wind conditions and because there is more available space for large wind farms out in the open sea. Vindeby Wind Farm in southern Denmark was constructed in 1991. As the world’s first offshore wind farm, it provided valuable information and experience for researchers and designers that have led to new technologies and design improvements, a trend that will continue as more offshore wind farms are constructed. Today, the world’s capacity of the installed offshore wind turbines exceeds 1,000 MW. Most of these are installed in Northern Europe where there was early political support and favorable conditions, such as strong winds and relatively shallow waters. Offshore wind projects are now under development around the globe, including continental Europe, the U.K. and North America. ‘The largest offshore wind farm today is Denmark’s Nysted Offshore Wind Farm, which has a total capacity of approximately 480,000 MWh, equivalent to the yearly consumption of 120,000 households. It is five to six miles offshore in the Baltic Sea in the southern part of Denmark.The owner is a joint venture between DONG Energy of Denmark and E.ON Sweden. Bonus Energy (now Siemens) supplied the wind turbines, and P. Aarsleff A/S and subcontractors supplied the foundations. The contractor’s consultant, COWI A/S of Denmark, developed and designed the turbine foundations. With a total capacity of 165.6 MW, the project consists of 72 Bonus 2.3 MW turbines in water depths up to 33 ft. The turbines have a hub height of 226 ft, and the turbine blade diameter is 270 ft. The rotor and nacelle (the structure that houses the generator, gearbox and other equipment) weigh approximately 150 tons, and the weight of the steel tower is approximately 130 tons. The wind farm site is located in a relatively protected area of the Baltic Sea, but during the winter months, the water often freezes and the foundations needed to be constructed to resist ice forces. The founding soils at the site are overconsolidated clay tills with boulders and with a thin layer of softer surface sediments. Pockets of up to 30 ft of soft sediments were encountered, which required special foundation preparations."

Jan 1, 2009