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By Steffen Schweizer, Tadeusz Brzozowski, Alfred Koller, Michał Topolnicki, Jürgen Wäger, Grzegorz Sołtys

A full scale test has been conducted to determine ground bearing pressure under rig tracks. The track loads were recorded in real time using Liebherr's Ground Pressure Visualisation system, and the vertical stress induced in the ground was measured with pressure cells embedded in the ground. It has been found that the recommendation of EN 16228 regarding determination of the track length is oversimplified. The contact length should dependent on the susceptibility of the working platform. It has been also demonstrated that the corrected pressure distributions under the tracks influence the dimensioning of the working platforms. As a result, the designed working platform may actually be less secure than is shown by conventional calculations.

May 1, 2022

By Walter E. Vanderpool

Type 1B micropiles (Bruce and Juran, 1997) can be installed rapidly and efficiently. During an 85-day period, 536 micropiles were installed to depths of 61 meters within a site 41 meters by 43 meters. Their performance, as measured by load test, varied even where the materials, construction procedure, and installation technique were closely monitored and controlled. The variation in displacement, as measured by the standard deviation, exceeded 50 percent of the mean test-load displacement for all loads up to the maximum load applied (2670 kN). This study provides a statistical basis to predict variability with respect to the construction method, micropile materials, and installation technique. The variability of displacement at all test loads is a fundamental characteristic of this type of drilled deep foundation system.

Jan 1, 2002

By Melinda J. Hummel, Zachary T. Smith, Nathaniel Witter, Nina F. Carney

The revitalization of Pittsburgh’s historic Strip District has led to the redevelopment of existing properties and the development of new properties. At one time, the Strip was home to wholesale market products. Now, the historical warehouse buildings are being converted to multi-use residential and commercial properties. One such property, 1600 Smallman Street, consisted of 1 to 6-story connected buildings that housed night clubs, retail shops, and office space. The lower story portion of the building, on the southwest side of the property, was torn down to make room for a new 5-story- parking garage with street level retail space. The remaining 6-story-building, on the northeast, was gutted to be renovated into high-end condominiums, keeping the exterior historical building facade.

By Steve Davidow, Scott Tunison

As the demand for electric power grows and generation facilities are constructed in more remote areas, the industry faces an increasing number of foundation construction challenges. The importance of quality geotechnical information prior to construction is accentuated by the linear nature of the projects and the potential for drastic changes from one end to the other, but is often difficult or unfeasible to obtain. Alignments are crossing remote, rugged and/or environmentally protected terrain, and completing a comprehensive geotechnical program is made challenging from an access or economic standpoint, or both. In these situations, the industry needs a flexible foundation alternative. This paper will present micropiles as that alternative and demonstrate how the implementation of micropile foundations mitigated these challenges on the Koolau-Wailupe 46 kV Circuits in Oahu, Hawaii, which involved rugged, steep slopes and helicopter construction methods. It will detail the selection of micropiles over other foundation options, micropile and steel pile cap design methodologies, foundation construction, and quality control. Special attention will be given to the unique geology in the area, and why precise identification of saprolite and basalt layers was integral to the successful performance of the foundations. The intention is to communicate the benefits of a flexible solution based on continuous collaboration between design and construction.

By M. D. Riegel, P. B. Pizzimenti, E. M. Zamiskie, Britain A. Materek

"The Skanska/Kiewit/ECCO III team (SKE) in association with HNTB was awarded the design-build contract for Phase I of the Kosciuszko Bridge Replacement Project. As lead designer for the SKE team, HNTB was responsible for the design of the Brooklyn Connector which includes construction of approximately 2000 feet of new staged earth-filled embankments utilizing prefabricated modular retaining walls (T-Walls®). The proposed embankments will be constructed adjacent to and beneath the existing Brooklyn Queens Expressway (BQE) viaduct while the existing viaduct remains in service. Critical aspects of the settlement assessment relating to the soils supporting the existing BQE will be addressed, as their behavior drives the deformation of the viaduct. Furthermore, a construction monitoring program was used to enable the designer to assess settlement predictions and allow SKE to mitigate potential impacts to the existing BQE during construction. Additionally, the methodology for installation of the embankments in a limited access area underneath an active viaduct supported on settlement sensitive shallow foundations will be presented.INTRODUCTIONSkanska-Kiewit-ECCO III Joint Venture, in association with HNTB was contracted by the New York State Department of Transportation (NYSDOT) to design and construct the Phase 1 replacement of the Kosciuszko Bridge Design-Build Project. Phase 1 of the project involves the design and construction of the new eastbound structures of Interstate 278 over Newtown Creek from Brooklyn to Queens. The project runs between Morgan Avenue in Brooklyn and the Long Island Expressway Interchange in Queens (approx. 1.1 miles) and includes the staged demolition of the existing structures."

Jan 1, 2016

By Satyajit Vaidya, Rudolph Frizzi, Quadri Owokoniran

"This paper presents a case history in the design and construction of high-capacity drilled shafts for the iconic New York Wheel presently being constructed along the St. George area waterfront in northern Staten Island, New York. Although the site is located in an area that offers views of the Statue of Liberty, the Manhattan skyline, and New York Harbor, the variable and challenging subsurface conditions at the site and the structural loading requirements for Wheel erection and service conditions presented geotechnical design and construction challenges. The paper focuses on site and subsurface conditions, drilled shaft design and construction details, results of Osterberg-cell and lateral load testing, and load test data analysis and evaluation.PROJECT DESCRIPTIONThe proposed 630-foot (190 m) -tall New York Wheel (the Wheel) is projected to be one of the tallest observation wheels in the world. Upon completion, the Wheel will be capable of carrying over 1,400 passengers in its 36 capsules. The Wheel site is located along New York Harbor offering views of the Statue of Liberty, the Manhattan skyline, and the New York Harbor; see Fig. 1. The Wheel structure is sited along the waterfront, and served by a 3-story terminal located south of the Wheel in the eastern portion of the site and having a footprint area of about 34,250 sq-ft (3,180 sq-m). A 4-story parking Garage, with a footprint of about 112,840 sq-ft (10,480 sqm), is to be constructed south of the Wheel in the central and western portions of the site.SITE AND SUBSURFACE CONDITIONSThe site’s close proximity to the New York Harbor presented geotechnical challenges because the site is located in an area that was once beyond the historic shoreline of Staten Island. The site is an about 350,000-sq-ft (32,500-sq-m) parcel generally bounded by the Richmond County Bank Ballpark to the southeast, the 9-11 Memorial to the east, Bank Street to the north and northeast, and Richmond Terrace and an associated retaining wall to the southwest and south. A 50-ft (15-m) -wide New York City Transit Easement, with an active on-grade service area and tracks, is located in the southern portion of the site. See Fig. 2 for site location and approximate location of the Wheel foundation footprint."

Jan 1, 2016

By Benjamin Jennings, Jason Herron

In the summer of 2016 Xcel Energy experienced a storm event that resulted in the collapse of approximately 8.5 miles of a 345 KV transmission line near Rogers, Minnesota. In design of the new transmission line, Xcel Energy determined that ten tower locations would be replaced with steel H-frame structures supported by helical piles instead of wood H-frame structures supported by driven wooden piles. A steel foundation was proposed for the towers due to time constraints and site conditions unfavorable to large pile driving equipment. Xcel Energy contacted the helical pile manufacturer Hubbell Power Systems, Inc. (HPS) for aid in the design of a complete steel foundation for the structure legs. With the shear, moment, and axial loads provided, the manufacturer used pile group modeling and axial capacity software to design a four helical pile group; and used 3D modeling and finite element software to design a moment resistant grillage to connect to the tower base. The steel grillage utilizes a new moment resistant connection and clamp system to transfer loads from the piles to the grillage. This connection provides a true fixed head condition and reduces lateral deflection issues typical to smaller diameter piles in pinned head connections. The clamp is designed to deform the helical pipe pile shaft and transfer the full axial load of the structure through the mechanical and friction connection. The helical piles and the moment resistant grillage were manufactured with shorter than average lead times and a helical pile installation contractor performed the installation. An expedient plan of install was developed by the contractor that resulted in an average installation rate of one complete set of tower foundations per day. The design of the moment resistant grillage, clamping system, and excellent foundation construction by the contractor provided an expedient and efficient foundation system to be discussed in this paper.

Jan 1, 2017

By Davide Grassi, Joel Joaquin Cortez, Giovanni Spagnoli, Nick Chittenden

Grouting is a technique used to improve the engineering properties of soils and rocks. Grouting techniques are classified under different criteria: injection method used, type of grout material injected, typical application, and the sequence of construction. The best-known criterion is the mode of entrance or admission of grout into the soil or rock. It is possible to identify therefore several grouting techniques: compaction, fracture, jet/mixing and permeation. The function of penetration grouting is to reduce the permeability of the soil or rock and/or increase the strength and density. In order to avoid displacement, permeation grouting shall be carried out at carefully controlled pressures and flow rates, using appropriate grouts. Colloidal silica is an innovative binder which has low viscosity (about 5 m·Pas), it is not toxic (pH lower than 9) and it is workable between +5°C and +45°C. This paper presents several case histories: a consolidation job related to the installation of a new sewer in North Italy in cohesionless soils, water stopping injection in a weathered granitic bedrock in California, permeation works in the US in sandy soils to improve excavation and the installation of sheet piles in the UAE. Results show that the colloidal silica an innovative and robust technology to perform grouting in very fine soils where conventional binders or micro-fine cements cannot penetrate.

May 1, 2022

By Patrick J. Hannigan, Frank Rausche, Rozbeh B. Moghaddam

Large diameter open-end pipe piles are increasingly used as deep foundations to support heavy onshore and offshore structures. During the driving process, several factors such as subsurface conditions, hammer type, hammer efficiency, pile type, plug conditions, temporarily increased base resistance, and loss of shaft resistance have direct impact on the driveability of large diameter open-end pipe piles. In a uniform subsurface condition, the unit shaft resistance increases with depth. Consequently, more resistance is accumulated as piles penetrate to greater depths which results in higher driving resistance. However, according to the friction fatigue analysis, the greater the number of shearing cycles occurring on a soil segment along the pile shaft, the greater the reduction of its shear resistance. As a consequence, since upper soil layers are subjected to a greater number of blows than those at greater depths, they have a relatively lower resistance compared to what would be calculated with standard geotechnical analysis methods. As a result of this progressive and nonuniform loss of shaft resistance with driving, blowcounts tend to increase at a lower rate than expected from traditional analyses. This paper discusses one of the approaches to the driveability analysis with the geotechnical friction fatigue consideration. It also shows comparisons between predicted driveability obtained from wave equation analysis and field driving records. All analyses were performed for a 2.134 m (7.0 ft) diameter open-end pipe pile installed at a total depth of 192.90 m (554 ft). Two separate static resistance and wave equation analyses were completed for the case study presented in this paper: 1) Friction Fatigue analysis based on the recommendations of Alm and Hamre (2001), subsequently referred to as the FF model, and 2) Standard Driveability analysis based on soil set- up factors, hereafter referred to as the SD model in this paper. Results from analyses included the shaft resistance distributions compared to the result of the signal matching analyses determined from the pile dynamic measurement. Furthermore, predicted blowcounts were compared to observed blowcounts during the pile driving. The comparison analyses indicated a 54.4 percent resistance loss of the Static Resistance during Driving (SRD) due to the geotechnical friction fatigue corresponding to a 46 percent reduction in total resistance. The analyses also showed that average predicted blowcounts using the friction fatigue were 6.4 percent lower than measured blowcounts, whereas, the standard driveability approach showed 42.1 percent higher blowcounts compared to the blowcounts shown in the driving log values.

Jan 1, 2019

By Lenin T., Madhav M. R., Padmavathi V.

Use of PVDs and preloading on the ground can significantly reduce the time taken for ground to consolidate. Many soils in situ are lightly overconsolidated, with overconsolidation ratios (OCR) ranging from 1.0 to 2.0 due to various reasons such as glaciation, ground water level fluctuation, aging, cyclic loading, creep, erosion, cementation, etc. The effects of overconsolidation ratio are analysed in this study. Compression index and consolidation coefficient are important parameters in determining time – settlement response of soft soils under preloading and with PVDs. These parameters are typically estimated using oedometer tests on samples, with the assumption that the results represent the entire deposit. The in-situ time-settlement plots at different depths are used in the back analysis for estimating compressibility and consolidation parameters of in situ ground, resulting in more representative values that reflect the deposit's overall behavior. From observed time versus settlements plots, variations of compression index and coefficient of consolidation with depth of a deposit are presented. Estimation of compression index with depth is possible based on different OCR values as shown in this study. Barron (1948), Asaoka methods are used to estimate the coefficient of consolidation with flow in the radial direction.

Sep 1, 2022

By Edward Jacobsen

The Oak Creek Power Plant in Oak Creek, Wisconsin is currently undertaking an expansion project. In order to supply cooling water to this facility, a 27' (8.2m) diameter tunnel will be bored, in rock; to connect to 4 vertical Intake shafts located approximately 1.5 miles (2.4km) offshore in Lake Michigan. In 2004, Case Foundation Company was awarded a lump sum contract to Install these intake shafts. When complete, the plant is expected to circulate upward of 2 billion gallons per day (7.5 billion liters) through this system. Two shafts were drilled in a (shortened) construction season in 2005 and the remaining 2 shafts and 4 liner assemblies were completed in 2006. Future connection to the tunnel, in 2007, will be accomplished by mining upward to reach the lower portion of each liner and then removing its internal bulkheads to permit the flow of the lake water into the tunnel.

May 11, 2007

By Ronaldo Luna, Donald Deardorff

"The use of load and resistance factor design (LRFD) is well documented since the 1960s for structural applications when it was first adopted into the American Concrete Institute Building Code in 1963 and was established for geotechnical applications by the Danish Geotechnical Institute about the same time under the name of Limit State Design (LSD).The Federal Highway Administration required all federally funded projects to use the LRFD method by 2007. Due to this funding requirement, recent LRFD research for geotechnical applications has focused on common bridge foundations (i.e., driven or drilled shafts), resulting in good documentation for design using these methods. Unfortunately, the practicing geotechnical engineer does not intuitively know how to create resistance factors for deep foundations systems that have design methodologies and installation techniques significantly different from driven or drilled shaft foundation systems.Helical anchors typically use semiempirical methods for preliminary capacity design and a torque correlation methodology during installation to verify required capacity. Here we provide basic information on the LRFD methodology for helical anchor design. Additionally, the First- Order Second Moment (FOSM) method is applied to a previous helical anchor study (Hoyt and Clemence 1989) to determine resistance factors for an ultimate tension capacity strength limit state.MethodologyThe concept of the LRFD method is to establish factors for both the load and resistance that account for uncertainties using probability theory. The factors increase the nominal load and/or decrease the nominal resistance such that the probability of failure is an acceptable value. LRFD also accounts for the effects of load combinations (dead, live, seismic, wind, etc.) by determining the probability of the combined occurrence. The general form of the LRFD equation used by American Association of State Highway and Transportation Officials (AASHTO) is:"

Jan 1, 2009

By Teresa M. Bodas Freitas, Arianna Lupattelli, Peter J. Bourne-Webb, Diana Salciarini, Martina Zito, Donatella Sterpi

The thermomechanical response of thermally-activated (TA) piles under monotonic thermal loads is quite well understood and the remaining uncertainties relate to the effect of long-term, cyclic loading of individual TA piles and pile groups. Recent studies undertaken by the authors have provided insights into the behaviour of TA pile foundations undergoing cyclic thermal loading. Despite their simplicity, the analyses show that key aspects of the observed response of piles in sand, under cyclic thermal loading can be reproduced, providing confidence in the outcomes of the analyses. The studies examined isolated piles and pile groups, and concluded that irrecoverable thermally-induced settlement may be mitigated through the choice of an appropriate margin of safety on the pile shaft resistance under service mechanical load conditions, and the maximum thermal stress can also be readily estimated. This paper consolidates these works and provides guidance regarding the safe geotechnical and structural design of the piles, then looks towards the remaining issues around the safe provision of thermally-activated pile foundations.

May 1, 2022

By Filippo Maria Leoni, George Filz, Wesley Schmutzler, Matteo Bertoni

"The US Army Corps of Engineers selected the Deep Mixing Method (DMM) for the required stabilization at the LPV 111 Project (New Orleans, USA). DMM was used for ground improvement/foundation strengthening and consequently to stabilize and support the burden of the new levee. Two different technologies were used: Trevi Turbo Mix (TTM) and Contrivance Innovation Cement Mixing Columns (CI-CMC). LPV 111 is the largest soil mixing project to date in the USA with its more than 18,000 elements installed to a depth of up to 67 feet for a total of 1.7 million cubic yards of treated soil. The preparation and execution of the project presented many challenges from various points of view. The little time available to complete the job led to the simultaneous utilization of eight deep mixing rigs and batch plants which worked 24 hours per day, 5.5 days per week on a stretch of land approximately 5.3 miles long. Given the imposing geographical extent of the project, a four phase laboratory programme and five field validation test programmes, conducted in as many different areas of the project, were completed to design and optimize the grout mixes and the installation parameters. The massive quality control/quality assurance testing programme produced over 500 drilled core holes and over 5,000 tested specimens in order to determine unconfined compressive strength (UCS) and uniformity of the DMM elements. This paper has the purposes of describing the tremendous challenges encountered and providing valuableinformation that may be useful for other future projects, including details not previously published.INTRODUCTIONReach LPV-111 is part of the Lake Pontchartrain and Vicinity Hurricane Protection System designed to protect the city of New Orleans and the surrounding areas from the surge that would accompany a 100 year hurricane event. LPV-111 measures approximately 8.5 km (5.3 miles) long, of which 7.2 (4.5 miles) extend along the north bank of the Gulf Intracoastal Waterway (GIWW) and the remaining 1.3 (0.8 miles) run north and terminates at the CSX Railroad Gate. The Bayou Sauvage National Wildlife Refuge borders the levee on both sides (Fig. 1)."

Jan 1, 2015

By Ganesh Deepak K., Anjana R. K., Dr. Kumar Pitchumani N., Rajasekharam R. M. V. M. S. S.

The Phase 2 of Chennai Metro is being introduced in the city to ease the dependence on the existing transportation systems. Phase 2 is a combination of underground and elevated metro stretches comprising of three corridors. The current study focusses on the underground stretch of Corridor 3 which has a total of 29 underground stations. Construction of the underground cut and cover stations results in ground movements, which in turn impact the structures adjacent to the excavations. The greenfield ground settlement can be evaluated with the help of empirical approach or an approach requiring finite element modelling (FEM). The paper compares empirical and FEM approaches with regards to ground conditions in Chennai. Further, with the predicted ground settlements, building damage assessment is performed. The damage category of a building is defined based on the estimated tensile strains. This paper also compares the building damage assessment with empirical method and finite element modelling.

Nov 1, 2022

By Arash Khosravifar, Nason McCullough, Stephen, Milad Souri, Scott Schlechter, E. Dickenson

The results of five centrifuge models were used to evaluate the response of pile-supported wharves subjected to inertial and liquefaction-induced lateral spreading loads. The centrifuge models contained pile groups that were embedded in rockfill dikes over layers of loose to dense sand and were shaken by a series of ground motions. The p-y curves were back-calculated for both dynamic and static loading from centrifuge data and were compared against commonly used API p-y relationships. It was found that a significant reduction in ultimate soil resistance occurred in dynamic p-y curves in partially/fully liquefied soils as compared to static p-y curves. It was also found that incorporating p-multipliers that are proportional to the pore water pressure ratio in granular materials is adequate for estimating pile demands in pseudo static analysis. 1. INTRODUCTION Liquefaction-induced ground deformations can cause severe damage to pile-supported wharves and other waterfront structures. A common approach in analyzing the lateral behavior of piles against seismic loads is using the beam on nonlinear Winkler foundation (BNWF) or p-y spring analysis. One common p-y relationship for sand is the one proposed by the American Petroleum Institute, also known as the API sand model (API 1993). While the API sand model was originally developed for the static loading conditions, it is common to modify the API sand curves for the effects of cyclic loading. However, there is no consensus on how to modify the static p-y curves for the effects of liquefaction and pore water pressure generation in loose granular soils. In previous studies, p-y springs of piles in liquefying soils were back-calculated from case histories, centrifuge model studies (e.g., Wilson et al. 2000; Brandenberg et al. 2005; Abdoun et al. 2003), full-scale tests (e.g., Rollins et al. 2005; Chang and Hutchinson 2013), and numerical analyses (e.g., McGann et al. 2011). In general, these studies found the softening effects of soil liquefaction on p-y curves, as well as a hardening behavior attributed to the dilative response of the liquefied soil around the pile. However, these studies provide varying recommendations on how to modify the static p-y curves to capture this complex behavior. Some design guidelines propose softening the static p-y curves using p-multipliers (e.g., Caltrans 2012). Other studies propose an upward concave shape for p-y curves in liquefied soils (e.g., Franke and Rollins 2013; Chang and Hutchinson 2013).

Jan 1, 2019

By Eleonora Di Mario, Colin B. Turnbull, Matthew G. Mills, Chengbin Miao, Wilhelm S. Degen

"In the past decade, the ‘zero-dredge’ philosophy has become the preferred option for the formation of marine seawalls and reclamations, compared to the partially or fully dredged options, as this solution presents several environmental advantages. Recent relevant project experience is presented herein in order to highlight key design principles and construction issues central to the successful construction and performance of a sloping rubble seawall founded on soft soil improved by stone columns. If designed and installed with proper quality control, correct treatment intensity and sensible construction staging, stone columns are a safe and cost effective method for seawall foundations. This paper provides guidelines with regards to the design, construction and quality control for the correct implementation of stone columns as a foundation element for sloping rubble marine seawalls.INTRODUCTIONBenefits of sloping marine seawalls founded on stone columnsTo suit the current environmental requirements in Hong Kong, recent projects are tending to favour zero-dredge solutions, such as the Hong Kong Boundary Crossing Facility and the forthcoming Three-Runway System. The installation of stone columns allows the underlying deposits, generally consisting of very soft to soft clay and silt (soft soil), to improve in strength to the extent that the seawall can be directly placed on the seabed. This negates the need to dredge the soft soil and, therefore, this ground improvement technique represents an ideal solution for zero-dredge projects.Stone columns can also provide several other beneficial effects, including: accelerated drainage, reduced settlement, increased slope stability and soil reinforcement in the event of an earthquake. Stone columns, in contrast to competing cementitious methods, are a very ductile foundation method. This ductile behaviour is part of the design concept of stone columns in soft soil. Past projects located in Hong Kong and elsewhere, with an improved soft soil layer thickness of over 15m, have shown that stone columns can remain fully functional in terms of both drainage and horizontal reinforcement, even after settlements of over 3m and lateral displacements of up to 1m have occurred."

Jan 1, 2017

By Thang V. Nguyen, Lisheng Shao, Gary E. Taylor

"The Community Memorial Hospital of Ventura, California, proposed to build a new state-of-the-art Cancer Treatment Center with radiation shielding walls and roof. The loose silty soils at the site had the potential to liquefy during an earthquake, which would result in significant settlement under the heavy footing loads. Treatment options included various deep foundation alternatives, as well as several ground improvement methods. The choice of wet soil mixing minimized the disturbance to the adjacent hospital during construction and potential settlement. Wet soil mixing allowed the structure to be supported on a raft foundation, meeting the stringent building total and differential settlement criteria. The authors also performed unit cell 3-D finite element analyses to evaluate the behavior of the wet soil mixing system in seismic loading conditions. This paper highlights the ground improvement design, construction, QA/QC, and the research related to evaluating the effectiveness of soil mixing for liquefaction mitigation.INTRODUCTIONThe Ventura Community Memorial Hospital proposed the construction of a new Cancer Treatment Center to replace the existing structure, which was built in 1901. The hospital complex is located in a wellestablished residential neighborhood. The soil conditions at the site of the proposed structure required ground modification to support the very heavy radiation treatment section of the building and limit settlement. Originally, 90-foot-long precast piles were considered for foundation support. Based on supplemental Cone Penetration Tests (CPTs) performed, the deepest CPT did not encounter competent pile bearing strata at a depth exceeding 30.5 m (100 ft). This could result in failure of the piles under long-term conditions, especially if hydro-consolidation occurs. The more realistic pile penetration depth would have been 36.6 to 45.7 m (120 to 150 ft). In addition, the excessive noise in association with pile driving would have been unacceptable to the community, patients, and staff of the hospital, so an alternative ground improvement solution was required.The specialty geotechnical contractor recommended wet soil mixing, an economical solution of creating a soil-cement product known as soilcrete that would significantly reduce the construction related noise and provide a more complete deep foundation for the structure.SOIL CONDITIONS AND SETTLEMENT CONCERNSThe subsurface soils were interbedded (Fig. 1) consisting of loose to medium dense silty sands, and soft to medium stiff silty clays to a depth of 30.5 m (100 ft). Groundwater was encountered at depths of 9.1 m (30 ft) and historical high groundwater was at 8.5 m (28 ft) below the ground surface."

Jan 1, 2015

By Patrick J. Hannigan, Frank Rausche, Rozbeh B. Moghaddam

The Top-Loaded Bi-Directional Test (“TLBT”) is a new method to apply bi-directional loads to a deep foundation element with the loading source located above the foundation head. In the TLBT reusable load assembly, loads are applied to the foundation using the R-System which consists of two stacked steel plates located at the geotechnical resistance balance point or at the foundation base connected to the load assembly via vertical elements. The top plate or the Shaft Bearing Plate (“SBP”) will transfer loads to the foundation upper portion, and the bottom plate or the Base Bearing Plate (“BBP”) will transfer loads to the foundation lower portion as well as the foundation base. At the surface, above the foundation head, a hydraulic jack is located between a Top Load Assembly (“TLA”), and the Bottom Load Assembly (“BLA”). The TLA and BLA are connected to vertical elements which are consequently connected to the R-system. As the jack is pressurized and expanded at the surface, the R-System plates are separated, and the foundation is bidirectionally loaded. This paper presents a brief description of the conventional Bi-Directional Load Test (“BDLT”) including benefits and limitations followed by the TLBT method introduction including its benefits and advantages over other testing methods.

Sep 8, 2021

By Rahul Wankhade, Sunil S. Baswankar, Aditya S. Kharatkar

Despite advances in pile design methodologies and piling techniques at site, difficulties and uncertainties still exists for design of piles particularly in coralline deposits and weak carbonate rocks. Such deposits are known to be heterogenous in nature, and occupy major stretches of earth, where piling experiences are probably very scanty. Such deposits are associated with low unit weights and usually consist of weakly cemented calcareous and carbonate soils interbedded with coral rocks containing cavities, which are completely void or filled with coral debris. Many of the studies indicate that conventional parametric relationships are may not apply to such sediments and rock formations. This paper intends to provide an appraisal of the available information that cautions against risks involved in conventional design practice and also serve as a guideline for pile design in such formations despite being a grey area of research. Contents of the paper is expected to provide a basis for the pile design and likely to serve as an eye-opener for research into this important soil-pile structure interaction problem.

Sep 1, 2022